CDA tappet with hydraulically controlled feed from outside engine block

Abstract

In one embodiment, a tappet assembly includes: a tappet having a latch mechanism; a slot disposed on an outer wall of the tappet and including an inlet providing access to the latch mechanism; and a pin including a fluid passage. The latch mechanism is switchable between a locked position and an unlocked position. The pin is configured to engage with the slot to prevent rotation of the tappet about the tappet axis. The fluid channel is configured to be fluidly coupled to the inlet of the slot.

Description

[0001] Citations of Related Applications

[0002] The present disclosure is based upon and claims the benefit of U.S. Provisional Application No. 63 / 348,632, filed on June 3, 2022, entitled “CDA lifter with hydraulic controlfeed from the engine block,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to a system for controlling cylinder deactivation (CDA), and more particularly to a CDA lifter having a hydraulically controlled feed from outside the engine block. Background Art

[0004] In the past, a variety of tappet designs for valve train systems of internal combustion engines have been produced. Typically, such tappets are coupled to a camshaft on one side and to an engine cylinder on the other side for transmitting actuation motion from the camshaft to downstream valves located in the cylinders. In particular for multi-cylinder engines, independent cylinder control for cylinder deactivation is highly desirable, for example, in order to better adjust the engine and / or fuel efficiency as required, i.e., a selected combination of cylinders can be disabled by deactivating the valves in those cylinders. Typically, in tappets configured to implement such CDA functionality, hydraulic switching components (e.g., latching mechanisms) are typically used, which in operation can quickly switch the system from an active mode (i.e., allowing the valve actuation motion provided by the camshaft to be transmitted to the cylinder) to a deactivated mode (e.g., the motion generated by the camshaft is absorbed by the hydraulic switching component, whereby the corresponding valve is not actuated), or vice versa, as required. However, this typically requires additional fluid passages that extend inside the engine block to feed control pressure to selected tappets, thereby significantly increasing the overall system complexity. Extensive machining is also required to recast the engine block to accommodate the complex passage design, making the construction process expensive and time consuming.

[0005] Therefore, there is a need to design a simplified system that allows hydraulic control of CDA operation without adding significant engine complexity. Summary of the invention

[0006] The present disclosure proposes a simplified tappet assembly for controlling CDA operation. Specifically, the tappet assembly according to the present disclosure utilizes a pin-slot combination to prevent undesired rotational movement of the roller tappet and simultaneously enables hydraulic control for CDA operation. In addition, the present disclosure proposes an engine block assembly that accommodates the tappets of these configurations and is adapted to receive hydraulic control feed from the outside.

[0007] By controlling the feed of fluid through the anti-rotation groove and the fluid passage of the pin, the need for an additional fluid circuit inside the engine block can be eliminated. In addition, since the pin can be mounted from outside the engine block, a hydraulic feed source can be supplied from the outside to the pin for controlling CDA switching. In this way, it can allow simple modification of existing engine conditions to accommodate CDA requirements, thereby reducing construction costs and program time.

[0008] An embodiment of a tappet assembly according to the present disclosure includes: a tappet having a latch mechanism; a slot disposed on an outer wall of the tappet and including an inlet providing access to the latch mechanism; and a pin including a fluid passage. Specifically, the latch mechanism is switchable between a locked position and an unlocked position. In the same embodiment, the pin is configured to engage with the slot so that the tappet is prevented from rotating about the tappet axis. In addition, the fluid passage is configured to be fluidically coupled to the inlet of the slot.

[0009] In a specific embodiment, the slot is elongated. In a specific embodiment, the length of the slot is configured to remain engaged with the pin when the tappet travels in a vertical direction. In a specific embodiment, the slot is configured to receive an end of the pin. In a specific embodiment, the width of the slot is slightly greater than the outer diameter of the end of the pin.

[0010] In a specific embodiment, when the pin is engaged with the slot, a gap is formed between the end of the pin and the bottom surface of the slot to allow fluid communication. In a specific embodiment, the inlet is arranged at the bottom surface of the slot. In a specific embodiment, when the tappet is in the base circle position, the fluid passage is adjacent to the inlet. In a specific embodiment, the latch mechanism is configured to switch to the unlocked position by means of fluid pressure supplied through the fluid passage of the pin.

[0011] In a specific embodiment, the tappet assembly is configured to be received inside an engine block. In a specific embodiment, the pin is configured to be installed externally into the engine block. In a specific embodiment, the fluid passage is configured to be fluidly coupled to a fluid supply device external to the engine block.

[0012] An embodiment of an engine block assembly according to the present disclosure includes: an engine block; a tappet assembly housed inside the engine block; and a pin mounted from outside the engine block and including a fluid passage. Specifically, the tappet assembly may include a tappet having a latch mechanism. The latch mechanism is switchable between a locked position and an unlocked position. In addition, the pin is configured to engage with a slot so as to prevent the tappet from rotating about a tappet axis. The fluid passage is configured to be fluidically coupled to an inlet of the slot.

[0013] In a specific embodiment, the fluid passage is configured to be fluidically connected to a fluid supply device outside the engine block. In a specific embodiment, the pin includes a head configured to be mounted against the outer wall of the engine block. In a specific embodiment, the pin includes a body portion configured to extend through the outer wall of the engine block. In a specific embodiment, the pin includes an end configured to fit into the groove. In a specific embodiment, the groove is elongated. In a specific embodiment, the length of the groove is configured to remain engaged with the pin when the tappet travels in a vertical direction. In a specific embodiment, when the pin engages with the groove, a gap is formed between the end of the pin and the bottom surface of the groove to allow fluid communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Embodiments according to the present disclosure will now be described with reference to the accompanying drawings, in which:

[0015] Figure 1 A tappet assembly according to the present disclosure is shown;

[0016] Figure 2 Shows Figure 1 A cross-sectional view of a tappet assembly;

[0017] Figure 3 A roller tappet according to the present disclosure is shown;

[0018] Figure 4 and Figure 5 shows respective isometric and cross-sectional views of a pin according to the present disclosure; and

[0019] Figure 6 The tappet assembly is shown in a base circle position and a maximum lift position, respectively. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to the examples shown in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. Directional references such as "upwardly," "downwardly," "rightwardly," and "leftwardly" are for ease of reference to the drawings and are not intended to limit the scope of the present disclosure.

[0021] Figure 1An exemplary tappet assembly 100 according to one embodiment of the present disclosure is shown, which is generally housed inside an engine block (not shown). In practice, a pair of tappet assemblies may be provided for each engine cylinder to perform intake and exhaust functions, respectively. However, for the sake of simplicity of the present disclosure, only one tappet assembly 100 is described below. Figure 1 The front part is shown in FIG.

[0022] In the illustrated embodiment, the tappet assembly 100 includes a roller tappet 110 that can travel on a camshaft 114 at its roller bearing 116 and is configured to reciprocate in a vertical direction along a tappet axis 118 in a controllable manner when actuated by rotation of the camshaft. As shown, the upper portion of the roller tappet 110 can be coupled to the lower end of a push rod 112, and the upper end of the push rod 112 can in turn engage a rocker arm (not shown). So configured, the vertical displacement of the roller tappet 110 (i.e., by rotation of the camshaft 114) can be transmitted to the rocker arm through the push rod 112, thereby causing the rocker arm to rotate to activate the associated cylinder as desired.

[0023] In a specific embodiment, the tappet assembly 100 can be configured to provide a so-called CDA function, i.e., systematically disabling selected cylinder combinations, for example for better fuel economy or overall engine efficiency, so that the system can operate on fewer cylinders when less power output is required. To this end, the roller tappet 110 can be provided with a variety of switching components to selectively enable and / or disable the transmission of motion from the camshaft 114 to the rocker arm. For example, these switching components can mechanically switch the roller tappet 110 between a locked mode for cylinder activation and an unlocked mode for cylinder deactivation. Reference will be made to the following. Figure 2 Describes the details of the switching component.

[0024] Figure 2 A cross-sectional view of the tappet assembly 100 taken along the tappet axis 118 is shown. In a particular embodiment, the roller tappet 110 may include an outer body 212 and an inner body 214, the inner body being located inside the outer body 212 and configured to be able to travel vertically relative to the outer body 212 as desired. For example, the inner body 214 may include a foldable latch mechanism 216, which is housed in a chamber 224 and is designed to mechanically switch between a locked position and an unlocked position. As an example and not a limiting manner, the latch mechanism 216 may include two locking pins 220, 222 and a spring 218 connected therebetween. In operation, the inner body 214 may be fixed in a default locked position relative to the outer body 212, in which the biasing force applied by the spring 218 may push the two locking pins 220, 222 outward to engage with the annular recess 226 of the outer body 212. Figure 2This locking configuration is depicted. When this occurs, the inner body 214 is tightly locked with the outer body 212 by the latch mechanism 216 in the extended state, thereby enabling the transmission of motion through the roller tappet 110 to activate the associated engine cylinder. In other words, the system is in lift mode. Conversely, for example, when cylinder deactivation is required, hydraulic pressure can be transmitted to the chamber 224 to compress the locking pins 220, 222 so that the locking pins 220, 222 are retracted from the annular recess 226 and disengaged. In this case, the inner body 214 is released and is free to translate in the vertical direction inside the outer body 212, so that any actuation motion applied via the camshaft 114 can be absorbed by the up and down displacement between the inner body 214 and the outer body 212. In some embodiments, a lost motion spring 228 can be arranged inside the roller tappet 110 to inhibit relative movement of the inner body 214 and the outer body 212. When switching back to lift mode, the hydraulic supply to the chamber 224 may be cut off and the spring 218 may again bias the two locking pins 220 , 222 outwardly to return to the locked position.

[0025] It will be understood that the switching components described herein are exemplary only and are not intended to limit the scope of the present disclosure. Although the switching of the roller tappet is described above by specific components, these components are provided for illustrative purposes only and are not necessarily required. In some embodiments, one or more components may be omitted from or added to the roller tappet. Other suitable configurations of the roller tappet may be apparent to those skilled in the art and are not exhaustively described in this disclosure.

[0026] Continue to refer Figure 1 and Figure 2, the roller tappet 110 according to the present disclosure further includes a groove 120, which can be configured to receive a pin 122. For example, the pin 122 can act as an anti-rotation pin, which engages with the groove 120, so that any rotational movement of the roller tappet 110 about the tappet axis 118 can be prevented. Therefore, the roller tappet 110 can maintain a proper orientation inside the tappet bore (not shown), thereby ensuring that the roller bearing 116 is aligned with the camshaft 114 and minimizing undesirable wear. In addition, the groove 120 can advantageously include an inlet 230 leading to the interior of the roller tappet 110. For example, the inlet 230 can be located near the annular recess 226, so that when the latch mechanism 216 engages the annular recess 226 in the locked configuration, the inlet 230 can provide access to the latch mechanism 216. Correspondingly, in a specific embodiment, a fluid channel 232 can be arranged in the pin 122. The fluid passage 232 may be configured to be fluidically coupled to the inlet 230 for feeding fluid into the inlet 230. For example, in operation, to control cylinder deactivation, hydraulic pressure may be transmitted to the pin 122, for example, via an external fluid supply source, to the slot 120 through the fluid passage 232, and finally to the inlet 230. Thus, the internally located latch mechanism 216 may be collapsed under the action of the hydraulic pressure, thereby switching the roller tappet 110 to the deactivated mode.

[0027] In a configuration where the tappet assembly 100 is housed by an engine block, the pin 122 can be mounted from outside the engine block. For example, a through hole can be opened on the outer wall of the engine block by, for example, drilling, boring, or other suitable methods known to those skilled in the art. The pin 122 can be assembled into the through hole and further extended inwardly to engage with the roller tappet 110. In a specific embodiment, a fluid supply device such as an oil control valve or other suitable fluid source known to those skilled in the art can be connected to the pin 122 for feeding fluid to the roller tappet 110. As a non-limiting example, the fluid supply device can be constructed outside the engine block and optionally include a mounting structure that can be located above the pin 122 and fluidly connected to the pin 122. Of course, it will be understood that although shown as such, the present disclosure is not limited thereto. The present disclosure also contemplates other suitable configurations of the fluid supply device. For example, a pipeline or manifold can be directed to the pin 122 for providing hydraulic feed.

[0028] For conventional systems to control cylinder deactivation, a separate fluid circuit is typically required that is routed to the roller tappets inside the engine block in order to hydraulically control switching. However, this results in complex channel design of the engine architecture and requires recasting and / or redesign of the engine block, which significantly increases cost and program time. The design of the tappet assembly 100 according to the present disclosure contrasts with prior art designs in that it combines fluid feed and anti-rotation capability into a single pin groove configuration, thereby significantly reducing the design complexity of the entire system and making the machining process simpler and more cost-effective. In addition, by routing the hydraulic control feed externally to the engine block, the system disclosed herein eliminates the need to recast the engine and enables simple modifications to existing engine conditions, allowing the engine block to be easily adapted to accommodate specific customer requirements.

[0029] Figure 3 An isolated view of the roller tappet 110 is shown, specifically showing the groove 120. In this embodiment, the groove 120 can be located on the outer wall of the roller tappet 110, such as on the outer surface of the outer body 212. The groove 120 is adapted to engage with the pin 122. By way of example and not limitation, the groove 120 can be generally elongated and oriented parallel to the axis of the tappet. For example, the length of the groove 120 can be configured to accommodate the stroke of the tappet so that the groove 120 can remain engaged with the pin 122 when the roller tappet 110 reciprocates vertically. As another example, the width of the groove 120 can be slightly greater than or substantially equal to the end of the pin 122 (e.g., as shown in FIG. 1 ). Figure 4 and Figure 5 10 ). So configured, slot 120 can receive pin 122 so as to prevent roller tappet 110 from rotating about the tappet axis while still allowing pin 122 to travel in a vertical direction relative to roller tappet 110. As another example, slot 120 can be designed to have a depth such that when pin 122 is properly inserted, a certain gap exists between the end of pin 122 and the bottom surface of slot 120. In this way, when fluid is fed to roller tappet 110, a hydraulic connection between roller tappet 110 and pin 122 can be maintained to maintain fluid pressure at a desired level, thereby compressing latch mechanism 216 as needed.

[0030] In a particular embodiment, the slot 120 may include an inlet 230. For example, the inlet 230 may be disposed at a bottom surface of the slot 120 and provide access to the internal structure of the roller tappet 110. In one embodiment, the inlet 230 may be located in a vertical position that is generally aligned with the latch mechanism 216 in the locked configuration. In this manner, fluid may be delivered into the roller tappet 110 through the inlet 230 to act on the latch mechanism 216 to control a switching event.

[0031] Figure 4 and Figure 5 A pin 122 according to the present disclosure is shown. As already explained, the pin 122 may be adapted to engage with the slot 120 of the roller tappet 110. In a specific embodiment, the pin 122 may be configured to have a through passage 232, which may serve as a fluid passage for supplying fluid to the inlet 230 of the roller tappet 110. The through passage 232 may extend in a horizontal direction through the entire body of the pin 122. In a specific embodiment, the pin 122 may include an end 410, which may be adapted to be received in the slot 120 of the roller tappet 110. For example, the end 410 may be generally cylindrical and have a reduced diameter compared to the rest of the pin 122. When received, the end 410 may guide the vertical movement of the pin 212 along the slot 120, and at the same time resist rotation of the roller tappet 110 about the tappet axis. In a specific embodiment, the pin 122 may also include a head 412. For example, in the case where the pin 122 is mounted to the engine block from the outside (e.g., by means of a mounting hole), the head 412 can be pressed against the outer wall of the engine block, while the main body 414 of the pin 122 can extend through the outer wall. In some exemplary embodiments, although not shown, in order to facilitate the installation of the pin 122, the outer surface of the pin 122 can be threaded so that the pin 122 can be screwed into the engine block. In addition or alternatively, other suitable mounting features (e.g., fasteners, clamps, etc.) can be provided to help fix the pin 122 in place. In a specific embodiment, the head 412 can be connected to a fluid supply device. For example, the head 412 can be configured to facilitate such a fluid connection. In the illustrated embodiment, the head 412 can include a cavity 416, which is suitable for receiving the supplied fluid and guiding it to the through passage 232. As further shown, the head 412 can take a form similar to a bolt having a hexagonal structure so as to be assembled into the fluid supply device. Although described in this way, it will be understood by those skilled in the art that the pin 122 can be formed differently to perform the desired function of the present disclosure.

[0032] Figure 6The tappet assembly 100 is schematically shown when located in a base circle position and a maximum lift position, respectively. As shown, the tappet assembly 100 is housed inside the engine block 610. The pin 122 is inserted through the outer wall of the engine block 610 and further extends inwardly to engage with the slot 120 of the roller tappet 110 located inside the engine block 610. Although not shown, a fluid circuit can be coupled to the pin 122 from outside the engine block 610 to feed hydraulic pressure to the roller tappet 110 to control the CDA function as desired. During operation, when the roller tappet 110 is located on the base circle (i.e., the lowest position receiving zero lift from the camshaft as shown on the left side of the figure), the pin 122 can be located relative to the roller tappet 110 in a position where the pin 122 is directly aligned with the latch mechanism 216. In some embodiments, it may be desirable to switch in this configuration, wherein fluid can flow through the pin 122 and push the latch mechanism 216 to the unlocked position. When the roller tappet 110 is located Figure 6 In the maximum lift position shown on the right side of FIG, the pin 122 may be located at a lower position in the slot 120. If cylinder deactivation is still required, fluid may still be supplied from the pin 122 to the inlet 230 via the gap between the end of the pin 122 and the bottom surface of the slot 120 to keep the latch mechanism 216 retracted.

[0033] As used herein, "or" is inclusive and not exclusive, unless expressly indicated otherwise or indicated by context. Thus, as used herein, "A or B" means "A, B, or both," unless expressly indicated otherwise or indicated by context. Furthermore, "and" is conjunctive and singular, unless expressly indicated otherwise or indicated by context. Thus, as used herein, "A and B" means "A and B, jointly or singly," unless expressly indicated otherwise or indicated by context.

[0034] The scope of the present disclosure covers all changes, substitutions, variations, alterations and modifications to the exemplary embodiments described or shown herein, which will be understood by those of ordinary skill in the art. The scope of the present disclosure is not limited to the exemplary embodiments described or shown herein. In addition, although the present disclosure describes and shows the corresponding embodiments herein as including specific parts, elements, features, functions, operations or steps, it will be understood by those of ordinary skill in the art that any of these embodiments may include any combination or arrangement of any parts, elements, features, functions, operations or steps described or shown anywhere herein. In addition, in the appended claims, references to devices or systems adapted to, arranged to, capable of, configured to, enabled, operable to, or operated to perform specific functions, or parts of devices or systems, cover whether the device, system or parts, or specific functions are activated, turned on or unlocked, as long as the device, system or parts are adapted, arranged, capable of, configured to, enabled, operable or operated. In addition, although the present disclosure describes or shows specific embodiments as providing specific advantages, specific embodiments may not provide these advantages, or provide some or all of these advantages.

Claims

1. A tappet assembly, comprising: A tappet including a latch mechanism that is switchable between a locked position and an unlocked position, a slot disposed on an outer wall of the tappet and including an entrance providing access to the latch mechanism, and pin, including fluid passage, wherein the pin is configured to engage the slot to prevent the tappet from rotating about a tappet axis, and wherein the fluid passage is configured to be fluidly coupled to the inlet of the slot.

2. The tappet assembly according to claim 1, wherein: The slot is elongated.

3. The tappet assembly according to claim 2, wherein: The slot has a length configured to remain engaged with the pin as the tappet travels in a vertical direction.

4. The tappet assembly according to claim 1, wherein: The slot is configured to receive an end of the pin.

5. The tappet assembly according to claim 4, wherein: The slot has a width slightly greater than an outer diameter of the end of the pin.

6. The tappet assembly according to claim 1, wherein: When the pin engages the slot, a gap is formed between an end of the pin and a bottom surface of the slot to allow fluid communication.

7. The tappet assembly according to claim 1, wherein: The inlet is arranged at a bottom surface of the trough.

8. The tappet assembly according to claim 1, wherein: When the tappet is in the base circle position, the fluid passage is adjacent to the inlet.

9. The tappet assembly according to claim 1, wherein: The latch mechanism is configured to be switched to the unlocked position by means of fluid pressure supplied via the fluid passage of the pin.

10. The tappet assembly according to claim 1, wherein: The tappet assembly is configured to be received within an engine block.

11. The tappet assembly according to claim 9, wherein: The pin is configured to be externally mounted into the engine block.

12. The tappet assembly according to claim 9, wherein: The fluid passage is configured to be fluidly coupled to a fluid supply external to the engine block.

13. An engine cylinder block assembly, comprising: Engine block; A tappet assembly is housed inside the engine block and includes: A tappet including a latch mechanism switchable between a locked position and an unlocked position, and a slot disposed on an outer wall of the tappet and including an entrance providing access to the latch mechanism; and a pin mounted externally from said engine block and including a fluid passage; wherein the pin is configured to engage the slot to prevent the tappet from rotating about a tappet axis, and wherein the fluid passage is configured to be fluidly coupled to the inlet of the slot.

14. The engine block assembly according to claim 13, wherein: The fluid passage is configured to be fluidly coupled to a fluid supply external to the engine block.

15. The engine block assembly according to claim 13, wherein: The pin includes a head configured to be mounted against an outer wall of the engine block.

16. The engine block assembly of claim 13, wherein: The pin includes a body portion configured to extend through an outer wall of the engine block.

17. The engine block assembly of claim 13, wherein: The pin includes an end configured to fit into the slot.

18. The engine block assembly of claim 13, wherein: The slot is elongated.

19. The engine block assembly according to claim 18, wherein: The slot has a length configured to remain engaged with the pin as the tappet travels in a vertical direction.

20. The engine block assembly of claim 13, wherein: When the pin engages the slot, a gap is formed between an end of the pin and a bottom surface of the slot to allow fluid communication.

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