Engine valve actuation system and lift arm assembly with lift arm oil injection port for cam roller lubrication

Abstract

An engine valve actuation system (20) includes a rotatable camshaft (22) having a cam lobe (23), and a lifter assembly (24) having a lifter arm (26) with a roller (34) in contact with the cam lobe (23). A bushing (54) is positioned in a pin bore (50) of the lifter arm (26) and journals the lifter arm (26) on a pin (52) for reciprocating motion in response to rotation of the camshaft (22). An oil inlet passage (58) extends to the pin bore (50), and an oil outlet passage (64) extends from the pin bore (50). The oil outlet passage (64) forms an oil jet port (68) defining an oil jet path (70) oriented for directing an oil jet at the roller (34) and / or the cam lobe (23). An oil supply groove (72) is formed in at least one of the lifter arm (26) or the bushing (54) and fluidly connects the oil inlet passage (58) to the oil outlet passage (64).

Description

Technical Field

[0001] The present invention generally relates to an engine valve actuation system, and more specifically to a lifting arm assembly in an engine valve actuation system, wherein an oil supply groove is formed between the lifting arm and the bushing, and supplies lubricating oil to an injection port defining an injection path oriented to intersect at least one of a roller or a cam cam. Background Technology

[0002] Valves, in their various forms, are well-known and widely used in internal combustion engines worldwide. A typical engine configuration includes one or more intake valves and one or more exhaust valves, each associated with a combustion cylinder in the engine. During the engine cycle, the valve actuation system is used to open and close the intake valves to allow fresh air, sometimes mixed with fuel or other gases, to enter the cylinders. After the combustion or expansion stroke, the valve actuation system is used to open the exhaust valves to allow combustion products to be expelled. The opening and closing of valves in an internal combustion engine is typically a very rapid and precisely timed process.

[0003] Rotatable camshafts, such as those connected to the engine crankshaft via gear trains, are typically used to actuate engine valves, where the valve actuation system converts the rotational motion of the camshaft into linear motion of the engine valve. For this purpose, a device called a valve tappet is typically coupled between the camshaft and the engine valve. The valve tappet utilizes a roller or other cam follower that contacts the rotating engine camshaft and moves linearly in response to contact with a non-circular cam lobe. Wear, performance degradation, or other problems are sometimes observed in the various actuation system components that are in contact with each other and rotating relative to each other. Various lubrication strategies have been employed in efforts to mitigate such phenomena in valve actuation systems. An exemplary engine valve actuation system for the design of camshaft and bearing lubrication is proposed in U.S. Patent No. 2,956,642 granted to A. Chaplin. While the strategies proposed by Chaplin et al. can have various applications, there is always room for improvement and alternative strategies. Summary of the Invention

[0004] In one aspect, an engine valve actuation system includes a rotatable camshaft having a cam cam lobe and a lifting arm assembly including a lifting arm. The lifting arm has a roller end, a roller mounted in the roller end and in contact with the cam cam lobe, a pin end having an outer surface, and an inner surface forming a pin bore. The lifting arm assembly also includes a pin extending through the pin bore and a bushing located in the pin bore and journal-connected to the pin to reciprocate in response to rotation of the camshaft. An inlet passage extends through the lifting arm assembly to the pin bore, and an outlet passage extends from the pin bore through the lifting arm. The outlet passage forms an injection port in its outer surface and defines an injection path oriented to intersect at least one of the roller or the cam cam lobe. An inlet groove is formed between the lifting arm and the bushing, fluidly connecting the inlet passage to the outlet passage.

[0005] On the other hand, a lifting arm assembly for an engine valve actuation system includes: a lifting arm having a forked roller end; a roller mounted to rotate in the fork and configured to contact a cam cam angle of a rotatable camshaft; a pin end having an outer surface; and an inner surface forming a pin hole defining a central axis for receiving the pin to support the reciprocating motion of the lifting arm in response to rotation of the camshaft. The lifting arm also has an oil outlet passage extending through the pin hole. The oil outlet passage includes an inlet leading to the pin hole and an injection port opening in the outer surface and defining an injection path from the outer surface, the injection port being oriented to intersect at least one of the roller or the cam cam angle. The lifting arm assembly also includes a bushing positioned in the pin hole and held at a fixed angle about the central axis. An oil supply groove is formed between the lifting arm and the bushing and is fluidly connected to the oil outlet passage.

[0006] In another aspect, a lifting arm for an engine valve actuation system includes: a lifting arm body having a roller end having a fork configured for mounting the roller, the roller contacting a cam cam lobe of a rotatable camshaft; and a pushrod lifter having an arcuate rod contact surface and an upwardly projecting wall extending circumferentially around the arcuate rod contact surface. The lifting arm body also includes a pin end having an outer surface and an inner surface forming a pin hole defining a central axis, and a connecting section extending between the roller end and the pin end. An oil outlet passage is located in the pin end and extends radially outward from an oil inlet leading to the pin hole to an oil injection port at the outer surface. Attached Figure Description

[0007] Figure 1 This is a diagram of an engine system according to one embodiment;

[0008] Figure 2 This is a perspective view of an engine valve actuation system for an engine system according to one embodiment;

[0009] Figure 3 This is a diagram of a lifting arm assembly according to one embodiment;

[0010] Figure 4 yes Figure 3 A side view of the cross-section of the lifting arm assembly;

[0011] Figure 5 yes Figure 3 and Figure 4 A detailed view of a portion of the lifting arm assembly;

[0012] Figure 6 yes Figure 3 and Figure 4 A cross-sectional side view of a portion of the lifting arm assembly;

[0013] Figure 7 This is a diagram of a lifting arm according to one embodiment;

[0014] Figure 8 This is a diagram of a lifting arm according to another embodiment;

[0015] Figure 9 This is a diagram of a lifting arm according to one embodiment;

[0016] Figure 10 This is a diagram of a bushing for a lifting arm assembly according to one embodiment;

[0017] Figure 11 yes Figure 9 Another diagram of the bushing; and

[0018] Figure 12 yes Figure 9 A detailed view of a portion of the bushing. Detailed Implementation

[0019] See Figure 1The diagram illustrates an internal combustion engine system 10 according to one embodiment. The internal combustion engine system 10 (hereinafter referred to as "engine system 10") includes an engine housing 12 in which combustion cylinders 14 are formed. The engine housing 12 may have any number of combustion cylinders formed therein, in any suitable arrangement, such as an inline configuration or a V-configuration, or another. A piston 16 is movable within the cylinder 14 between a top dead center position and a bottom dead center position, typically in a conventional four-stroke engine cycle. An engine valve 18 is shown as associated with the cylinder 14 and movable between an open position and a closed position to control a fluid connection between the cylinder 14 and an intake or exhaust duct (not shown). The engine valve 18 may be an intake valve or an exhaust valve, and may include one or more of a plurality of intake valves connected together via a valve bridge or the like, respectively, and one of the exhaust valves. In a practical implementation strategy, engine system 10 may include a direct injection compression ignition diesel engine; however, the invention is not limited thereto, and engine system 10 may be port-injected, supplied with a premixed charge of fuel and air formed upstream of engine housing 12, spark-ignited, or have a variety of other configurations or operating capabilities.

[0020] Engine system 10 also includes an engine valve actuation system 20 for actuating engine valve 18 between an open and closed position. While engine valve actuation system 20 is shown coupled to an engine valve having the characteristics of a gas exchange valve, in other cases, engine valve actuation system 20 may be configured to actuate other valves, such as components in a fuel injector. Engine valve actuation system 20 (hereinafter referred to as "actuation system 20") includes a rotatable camshaft 22 having a cam lobe angle 23. Camshaft 22 can be rotated by a drive mechanism (not shown) of engine system 10 and may include any number of cam lobe angles that rotate together with camshaft 22 when engine system 10 is in operation. Actuation system 20 also includes a push rod 27 coupled to a rocker arm 25, which in turn is coupled to engine valve 18. Lifting arm assembly 24 of actuation system 20 includes a lifting arm 26 configured to lift push rod 27 to reciprocate rocker arm 25 as camshaft 22 rotates. As will become clearer from the following description, the actuation system 20 is uniquely configured by the structure of the lifting arm assembly 24 in order to improve lubrication and reduce camshaft / cam cam lug wear or other wear.

[0021] Still referencing Figure 2-4Additional features of the actuation system 20 are shown in more detail. The lifting arm assembly 24 includes a lifting arm 26 having a lifting arm body 28. The description and discussion of the lifting arm 26 or the lifting arm body 28 herein should be understood as interchangeable. The lifting arm 26 includes a roller end 30 having a fork 32 configured for mounting a roller 34 such that the roller 34 rotates in contact with a cam cam angle 23. The roller end 30 also includes a push rod lifter 36 having an arcuate rod contact surface 38 that contacts the end of a push rod 27. An upwardly projecting wall 40 extends circumferentially around the arcuate rod contact surface 38.

[0022] The lifting arm 26 also includes a pin end 42 having an outer surface 44 and a lug 46 extending from the outer surface 44. The pin end 42 also includes an inner surface 48 forming a pin hole 50. The pin 52 extends through the pin hole 50 and can be supported at a fixed angle relative to the engine housing 12. A connecting section 56 extends between the roller end 30 and the pin end 42. The connecting section 56 can be necked and in the vertical direction ( Figure 4 (up and down direction) or horizontal direction ( Figure 4 The lifting arm assembly 24 is narrower than the roller end 30 and pin end 42 in at least one direction (in and out of the page), as is evident from the accompanying drawings. The lifting arm assembly 24 also includes a bushing 54 positioned in the pin hole 50 and held at a fixed angle relative to the central axis 98 defined by the pin hole 50, such as by interference fit. The bushing 54 is configured to journal-type connect the lifting arm 26 to the pin 52 for reciprocating motion in response to rotation of the camshaft 22. Therefore, it can be understood that the camshaft 22 rotates together with the cam cam angle 23, followed by the roller 34, to... Figure 1 In the diagram, the push rod 27 is actuated upwards, at which point the rising profile of the cam lob 23 contacts the roller 34, allowing the push rod 27 to move downwards, at which point the falling profile of the cam lob 23 subsequently contacts the roller 34. A valve return spring (unnumbered) resists the upward movement of the push rod 27 and helps to bias the push rod 27 downwards in a generally known manner based on the relative positions of the cam lobes 23.

[0023] Also refer to Figure 6The lifting arm assembly 24 also has an oil inlet passage 58 formed therein, which extends radially outward from an inlet opening 60 relative to the central axis 98 through a pin 52. The oil inlet passage 58 may form an outlet opening 62 supplying engine oil between the pin 52 and the bushing 54. Oil is conveyed from the opening 62 between the bushing 54 and the pin 52, including through an inner diameter groove in the bushing 54, as described below, to an opening 86 in the bushing 54. Oil is conveyed from the opening 86 between the bushing 54 and the inner surface 48, including through a supply groove, as described below. Between the bushing 54 and the inner surface 48, oil is supplied circumferentially to the outlet passage 64 around the central axis 98 via a “short path” or “long path” discussed further herein, and in any case traverses less than 360° around the central axis 98. Figure 6 In the diagram, arrows 71, 73, and 75 indicate the oil flow from passage 58 between pin 52 and bushing 54. Arrow 77 indicates the oil flow through a short path to oil outlet passage 64 between bushing 54 and inner surface 48.

[0024] The oil outlet passage 54 extends from the pin hole 50 through the lifting arm 26 and includes an inlet port 66 leading to the pin hole 50, as well as an oil injection port 68 formed in the outer surface 44. The oil injection port 68 defines an oil injection path 70 oriented to intersect at least one of the roller 34 or the cam convex angle 23. Also in a practical implementation, the outer surface 44 forms an arc 102 around the central axis 98, such as... Figure 4 As shown, the fuel injection port 68 is located on the arc 102 and oriented such that the fuel injection path 70 intersects with the cam lob angle 23, as... Figure 1 and Figure 2 As shown. Figure 9 Another view of the lifting arm 26 is shown, illustrating the exemplary positioning and orientation of the fuel injection port 68.

[0025] It has been observed that certain known engine valve actuation systems experience cam lobe wear of a wear or other damaging nature, which can lead to performance degradation and / or premature maintenance. This invention reflects the findings and observations that directly supplying oil to the interacting cam lobe and / or roller surfaces can be associated with improved lubrication that limits or completely eliminates the aforementioned problems. When the manner or path of oil supply to the injection port 68 is not optimal, the supply pressure of the oil entering and passing through the inlet passage 58 can make it possible to observe excessive oil pressure drop or insufficient oil flow. The actuation system 20, and in particular the lifting arm assembly 24, can be configured to provide the desired oil flow rate without excessively limiting oil pressure, or alternatively resulting in excessive oil flow and consumption. For this purpose, an oil supply groove 72 is formed between the lifting arm 26 and the bushing 54 to deliver oil via the path indicated by arrow 77 (or alternatively, the "long" path as described above), and fluidly connects the opening 86 in the bushing 54 to the outlet passage 64. An oil sump 63 may be formed in the inner surface 48 aligned with the opening 86. The oil supply groove 72 may be formed in the lifting arm 26, the bushing 54, or both, as discussed further herein.

[0026] The oil supply groove 72 defines a groove path from a first angular position relative to the central axis 98 and a second angular position relative to the oil outlet passage 64, which is also relative to the central axis 98. The groove path from the first angular position to the second angular position will typically be less than 360°. Figure 9 Another view of the lifting arm 26 is shown, in which the oil injection port 68 can be shown oriented to guide oil injection to the rollers or cam cam in the actuation system 20. Figure 4 As shown, the grooved path can define a circumferential angle 100 from the first corner position to the second corner position. In the illustrated embodiment, the circumferential angle 100 can be between 34° and 66°, corresponding to the short path between the opening 86 and the oil outlet passage 64. In the alternative "long path" embodiments discussed below, the grooved path can be defined with a circumferential angle between 66° and 360°. As used herein, the term "between" means excluded, so "between 66° and 360°" means less than 360°. It has been found that a grooved path that completely surrounds the bushing herein can result in reduced or no flow along the long path around the bushing, while the oil takes the short path.

[0027] exist Figure 5 As can be seen, the oil supply groove 72 extends just through the inlet port 66 and is formed in the inner surface 48, such that the oil supply groove 72 is covered or closed by the bushing 54. It is conceivable that the oil supply groove according to the invention can be alternatively or additionally formed in the bushing 54 itself. Therefore, the description and discussion herein regarding the circumferential extent or other features of the oil supply groove 72 in the lifting arm 26 can be understood by analogy with the oil supply groove in the bushing 54. Figure 5 It can also be noted that the inlet port 66 has a relatively narrow diameter 74, while the injection port 68 has a relatively large diameter 76. See also Figure 7 A three-dimensional view is shown, illustrating the circumferential extent of the oil supply groove 72 in the inner surface 48. The oil supply groove 72 can be formed in the inner surface 48 by machining, and is typically formed at approximately halfway between the lateral sides of the lifting arm 26.

[0028] Figure 8 Alternative embodiments are illustrated, wherein the oil supply groove 172 in the lifting arm 126 takes a "long path" of less than 360° around the corresponding inner surface 148 in the lifting arm 126 between the first groove end 173 and the second groove end 175. It is understood that a bushing (not shown) may mate with the lifting arm 126 or other lifting arm embodiments contemplated herein to form a closed groove path with the oil supply groove 172 to supply oil to the oil outlet passage forming the injection port in the lifting arm 126, its positioning and orientation similar to other embodiments herein. In variations and extensions of the invention, the oil inlet passage may supply oil to the pin end in the lifting arm via, for example, different routes extending through the lifting arm body, and / or the oil outlet passage may exit the lifting arm at a location different from that shown in the invention. In any case, different lifting arm and engine configurations may necessitate different injection outlet locations, different internal oil passage pipes, or other modifications. In any embodiment, providing an oil supply groove formed by the lifting arm and / or bushing can provide a tortuous flow path, thereby making it easier to balance flow rate and oil pressure drop considerations compared to efforts to tightly specify the dimensions of ports, passages, or other features, which may often have tolerances that are difficult to control with very small dimensions.

[0029] Now go to Figure 10-12The figure shows a bushing 154 according to one embodiment. Bushing 154 may be similar to or the same as bushing 54 described above, but is indicated by different reference numerals for convenience. Bushing 154 is configured to provide an oil supply groove 90 that extends circumferentially around a generally cylindrical bushing body 80 between a first groove end 92 and a second groove end 94, defining a circumferential angle less than 360° and typically between 66° and 360°. Bushing body 80 may be formed from a rolled, generally flat metal blank having a first end 82 and a second end 84 connected at a connector 96. Connector 96 may be formed, for example, by an lap joint or any other suitable geometry. Opening 186 is formed in bushing body 80 and configured to supply oil from between bushing 154 and the pin described herein to between bushing 154 and the lifting arm body described herein. The opening 86 thus allows oil flow from the circumferential inner diameter groove 88 of the bushing body 80 to be supplied to the oil supply groove 90, and provides oil for lubrication between the bushing 154 and the pin, which is generally similar to the configuration in the lifting arm assembly 24. Figure 12 The illustration shows the dimensional properties of the oil supply groove 90 in the bushing body 80, and it can be seen that the oil supply groove 90 has a width dimension 104 and a depth dimension 106. The width dimension 104 is greater than the depth dimension 106. In a practical implementation strategy, the desired oil flow can be obtained when the ratio of the width dimension 104 to the depth dimension 106 is in the range of 2:1 to 8:1. In an improvement, the ratio of the width dimension 104 to the depth dimension 106 is from 3.5:1 to 6:1. It should also be understood that the dimensional and proportional properties associated with the oil supply groove 90 can be similar to or equivalent to the properties of the oil supply groove formed in the lifting arm, or partially formed in the lifting arm or partially formed in the bushing. In the illustrated embodiment, the oil supply groove 90 will be understood as defining a circumferential angle between 66° and 360° from the first groove end 92 to the second groove end 94. According to the invention, the bushing can also be configured to provide a short-path oil supply groove, wherein the circumferential angle defined between the first groove end and the second groove end will be between 34° and 66°.

[0030] Industrial applicability

[0031] Referring generally to the accompanying drawings, when engine system 10 is running, a fuel-air mixture is burned in cylinder 14, causing piston 16 to move between its top dead center and bottom dead center positions, thereby rotating the crankshaft in a conventional manner. The rotation of the crankshaft causes camshaft 22 to rotate, typically at half engine speed, to reciprocate the lifting arm assembly 24 based on the contact between roller 34 and cam cam lobes 23. As lifting arm 26 rises and falls, pushrod 27 is pushed upward via rocker arm 25 to open engine valve 18, and as lifting arm 26 falls, pushrod 27 moves downward with lifting arm 26. As described herein, oil is supplied into inlet passage 58, then flows and travels around the interface between bushing 54 and pin 52, and then through supply groove 72 to injection port 68. Oil is injected according to injection path 70, contacting cam lobes 23. The rotation of cam lobes 23 with contact roller 34 of camshaft 22 creates a lubricating film of oil between the contacting parts. As mentioned above, providing a lubricating film directly in this general manner tends to reduce or eliminate the momentary slowing or stopping of rotation between components, or the acceleration or deceleration that may cause the interfaces to slide and wear against each other.

[0032] As described above, one or more bushings or the lifting arm itself are used to provide the oil supply path, forming a labyrinthine flow path upstream of the injection port. The labyrinthine design allows for the regulation and control of the injector flow rate. Excessive flow may result in excessive oil pressure and / or reduced consumption, while insufficient flow may not provide adequate lubrication. The dimensions of the oil supply grooves and the length of the groove path traversing to supply the injection port can be varied to obtain the desired flow rate, which is advantageous considering the manufacturability challenges related to orifice size, compared to efforts to control flow rate solely through orifice or opening size. In the lifting arm assembly according to the invention, the manufacturability of the orifice size can be less than 1 mm, at least relative to inlet 66.

[0033] 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 the accompanying drawings and claims. As used herein, the articles “a” and “an” are intended to encompass one or more items and are used interchangeably with “one or more.” The term “one” or similar language is used when only one item is desired. Furthermore, as used herein, the term “has, have, having, etc.” is intended to be an open-ended term. Additionally, unless explicitly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.”

Claims

1. An engine valve actuation system (20), comprising: A rotatable camshaft (22) with a cam cam convex angle (23); The lifting arm assembly (24) includes: a lifting arm (26, 126) having a roller end (30) and a pin end (42), the pin end (42) having an outer surface (44) and an inner surface (48) forming a pin hole (50) defining a central axis; a roller (34) mounted in the roller end (30) and in contact with the cam cam (23); a pin (52) extending through the pin hole (50); and bushings (54, 154) positioned in the pin hole (50) and journal-connected to the pin (52) to reciprocate in response to rotation of the camshaft (22). The oil inlet passage (58) extends radially through the pin (52) to the pin hole (50); An oil outlet passage (64) extends from the pin hole (50) through the lifting arm (26, 126) and forms an oil injection port (68) in the outer surface (44), the oil injection port defining an oil injection path (70) oriented to intersect at least one of the roller (34) or the cam cam angle (23); and An oil supply groove (72, 172) is formed between the lifting arm (26, 126) and the bushing (54, 154) and fluidly connects the oil inlet passage (58) to the oil outlet passage (64). The oil supply groove (72, 172) defines a depth dimension extending radially outward relative to the central axis and a width dimension greater than the depth dimension. The ratio of the width dimension to the depth dimension is in the range of 2:1 to 8:

1.

2. The system (20) according to claim 1, wherein: The oil supply groove (72, 172) extends between a first angular position relative to the central axis and a second angular position relative to the central axis of the oil outlet passage (64); The oil inlet passage (58) is formed in the pin (52), and the inner diameter groove (88) in the bushing (54, 154) fluidly connects the oil inlet passage (58) to the oil supply groove (72, 172); and The oil supply groove (72, 172) defines a groove path of less than 360° from the first corner position to the second corner position.

3. The system (20) according to claim 2, wherein: The groove path is between 34° and 66° or between 66° and 360°; as well as The outer surface (44) forms an arc around the central axis, and the fuel injection port (68) is located on the arc and oriented such that the fuel injection path (70) intersects the cam cam angle (23).

4. A lifting arm assembly (24) for an engine valve actuation system (20), comprising: The lifting arm (26, 126) includes a roller end (30) with a fork (32), a roller (34) mounted to rotate in the fork (32) and configured to contact a cam cam (23) of a rotatable camshaft (22), a pin end (42) having an outer surface (44), and a pin hole (50) forming a defining central axis, and an inner surface (48) for receiving the pin (52) to support the lifting arm (26, 126) to reciprocate in response to the rotation of the camshaft (22). The lifting arm (26, 126) also has an oil outlet passage (64) extending from the pin hole (50) through the lifting arm (26, 126). The oil outlet passage (64) includes an inlet port (66) leading to the pin hole (50) and an oil injection port (68) opening in the outer surface (44) and defining an oil injection path (70) from the outer surface (44), the oil injection path being oriented to intersect at least one of the roller (34) or the cam convex angle (23). Bushings (54, 154) are positioned in the pin holes (50) and held at a fixed angle about the central axis; and Oil supply grooves (72, 172) are formed between the lifting arm (26, 126) and the bushing (54, 154) and are fluidly connected to the oil outlet passage (64). The oil supply groove (72, 172) defines a depth dimension extending radially outward relative to the central axis and a width dimension greater than the depth dimension, and the ratio of the width dimension to the depth dimension of the oil supply groove (72) is 3.5:1 to 6:

1.

5. The lifting arm assembly (24) according to claim 4, wherein: The oil supply groove (72, 172) extends between a first angular position relative to the central axis and a second angular position relative to the central axis of the oil outlet passage (64); The oil supply groove (72, 172) defines a groove path of less than 360° from the first corner position to the second corner position.

6. The lifting arm assembly (24) according to claim 4 or 5, wherein The oil supply groove (72) is formed in the inner surface (48) of the pin end (42).

7. The lifting arm assembly (24) according to claim 4 or 5, wherein the bushing (154) includes an outer bushing surface that is interference-fitted with the inner surface (48) of the lifting arm (26, 126), and the oil supply groove (172) is formed in the outer bushing surface.

8. The lifting arm assembly (24) according to claim 5, wherein the groove path is between 34° and 66°.

Images