Switchable lever arrangement

The present disclosure is generally related to a valve train of an internal combustion (IC) engine, particularly switchable levers that are utilized in the valve train.

Levers are utilized within valve trains of IC engines to facilitate translation of rotary motion of a camshaft to linear motion of an intake or exhaust valve. Switchable levers can include a locking part that can lock or unlock an inner lever to an outer lever to achieve different discrete valve lifts. The locking part can be actuated by hydraulic fluid which can require a series of hydraulic fluid galleries arranged throughout an engine. The locking part can also be actuated by an electric actuator. Use of an electric actuator instead of actuation by hydraulic fluid can offer several advantages including, but not limited to, wider operating temperature range, elimination of hydraulic fluid oil galleries, and faster actuation times. Packaging space within an IC engine can be very limited for switchable lever systems.

A switchable lever arrangement is provided that includes one or more switchable levers and a rotary actuator. The switchable lever includes an outer lever, an inner lever pivotably mounted to the outer lever, and a locking part capable of selectively locking the inner lever to the outer lever. The rotary actuator rotates about a rotational axis to actuate the locking part. The rotary actuator has a first locked position defined by a first effective actuation length of the rotary actuator relative to the rotational axis, and a second unlocked position defined by a second effective actuation length of the rotary actuator relative to the rotational axis, the second effective actuation length different than the first.

In one embodiment, the locking part includes a shuttle pin that is configured to engage the rotary actuator. The shuttle pin can be transverse to the switchable lever, and the rotational axis of the rotary actuator can be non-coaxial with a central axis of the shuttle pin.

The rotary actuator can include one or more fingers that are pivotably mounted to the rotary actuator, with the finger(s) configured to move to the first actuation length and the second actuation length by selective rotation of the rotary actuator. The rotary actuator can be electronically controlled.

In one embodiment, the switchable lever arrangement includes a first switchable lever and a second switchable lever, and the rotary actuator includes a first finger to actuate the first locking part of the first switchable lever, and a second finger to actuate the second locking part of the second switchable lever. A motion of one or both of the first or second fingers can be guided by a motion guide.

A switchable lever arrangement is provided that includes one or more switchable levers. The switchable lever includes an outer lever, an inner lever pivotably mounted to the outer lever, a locking part capable of selectively locking the inner lever to the outer lever, and a rotary actuator. The rotary actuator rotates about a rotational axis to actuate the locking part and continuously increases or decreases in effective actuation length as it moves from a first rotational angle to a second rotational angle. The rotary actuator can engage a portion of the locking part that moves within a first bore arranged transversely to the switchable lever. In one embodiment, the rotational axis is non-coaxial to the central axis of the first bore.

In one embodiment, the locking part can include a shuttle pin that moves within the first bore, and a locking pin that moves within a second bore, with the second bore orthogonal to the first bore.

In one embodiment, the rotary actuator includes one or more fingers that: (i) retract to a first effective actuation length to achieve a first locked position; and, (ii) extend to a second effective actuation length to achieve a second unlocked position. The first locked position can define a first valve lift mode and the second unlocked position can define a second valve lift mode. The first valve lift mode can be a full-valve-lift mode, and the second valve lift mode can be a no-valve-lift mode.

An actuator for a switchable valve train arrangement is provided that includes a rotary platform that is configured to rotate around a rotational axis to actuate a locking part of a switchable valve train component. The rotary platform has a first locked position defined by a first effective actuation length of the rotary platform relative to the rotational axis, and a second unlocked position defined by a second effective actuation length of the rotary platform relative to the rotational axis. The rotary platform can include one or more fingers pivotably mounted to the rotary platform. The finger can include a guide surface adapted to engage a motion guide, and a first end adapted to engage the locking part of the switchable valve train component. The actuator can include a solenoid that rotationally actuates the rotary platform.

A method of actuating a switchable valve train component is provided that includes:

1). Providing: a). a switchable valve train component having a first component, a second component, and a locking part that selectively locks the first component to the second component; and, b). a rotary actuator that rotates about the rotational axis to actuate the locking part.

2). Rotating the rotary actuator to continuously decrease an effective actuation length of the rotary actuator to move the locking part to a first locked position; and,

3). Rotating the rotary actuator to continuously increase an effective actuation length of the rotary actuator to move the locking part to a second unlocked position.

The foregoing Summary as well as the following Detailed Description will be best understood when read in conjunction with the appended drawings. In the drawings:

FIG. 1 is a perspective view of an example embodiment of a switchable valve train system that includes an actuator, a first switchable lever, a second switchable lever, a first camshaft lobe, a second camshaft lobe, a first pivot element, a second pivot element, a first engine valve, and a second engine valve.

FIG. 2 is a perspective view of the first switchable lever, second switchable lever, and actuator of FIG. 1 .

FIG. 3 is a perspective view of a first locking part of the first switchable lever of FIG. 2 .

FIG. 4A is a cross-sectional view of the first switchable lever of FIG. 2 in a first locked position.

FIG. 4B is a cross-sectional view of the first switchable lever of FIG. 2 in a second unlocked position.

FIG. 5A is an isometric view of a rotary platform of the actuator of FIG. 2 .

FIG. 5B is a top view of the rotary platform of FIG. 5A .

FIG. 6A is a cross-sectional view of the first and second switchable levers and the actuator of FIG. 2 in a first locked position.

FIG. 6B is a cross-sectional view of the first and second switchable levers and the actuator of FIG. 2 in a second unlocked position.

Certain terminology is used in the following description for convenience only and is not limiting. The words “inner,” “outer,” “inwardly,” and “outwardly” refer to directions towards and away from the parts referenced in the drawings. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, c or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import.

FIG. 1 shows a perspective view of an example embodiment of a switchable valve train system 100 that includes a rotary actuator 50 , a first switchable lever 10 A, a second switchable lever 10 B, a first camshaft lobe 92 A, a second camshaft lobe 92 B, a first pivot element 94 A, a second pivot element 94 B, a first engine valve 96 A, and a second engine valve 96 B. FIG. 2 shows a perspective view of the first and second switchable levers 10 A, 10 B and the rotary actuator 50 of FIG. 2 . FIG. 3 is a perspective view of a first locking part 30 A of the first switchable lever 10 A of FIG. 2 . FIGS. 4A and 4B show cross-sectional views of the first switchable lever 10 A of FIG. 2 in a respective first locked position and a second unlocked position. FIG. 5A is an isometric view of a rotary platform 58 of the rotary actuator 50 of FIG. 2 , while FIG. 5B is a top view of the rotary platform 58 of FIG. 5A . FIGS. 6A and 6B show cross-sectional views of the first and second switchable levers 10 A, 10 B and the rotary actuator 50 in respective first locked and second unlocked positions. The following discussion should be read in light of FIGS. 1 through 6B .

The rotary actuator 50 is arranged between the first switchable lever 10 A and the second switchable lever 10 B, having access to a first locking part 30 A and a second locking part 30 B of the respective first and second switchable levers 10 A, 10 B. It could also be stated that portions of the first and second locking parts 30 A, 30 B are exposed to receive an actuation force from outside of the first and second switchable levers 10 A, 10 B. Other than an orientation of the first locking part 30 A and second locking part 30 B such that they are accessible by the rotary actuator 50 placed between them, the first switchable lever 10 A and the second switchable lever 10 B are identical in design, utilizing the same components; however, different switchable lever designs are possible within the switchable valve train system 100 . A functional description now follows for the first switchable lever 10 A, which can also be applied to the second switchable lever 10 B.

The first switchable lever 10 A includes an outer lever 20 and an inner lever 12 . The inner lever 12 is pivotably mounted to the outer lever 20 by a pivot axle 48 . The first locking part 30 A can selectively lock the inner lever 12 to the outer lever 20 . The inner lever 12 includes a locking end 14 with a locking surface 15 and a hinge end 16 that receives the pivot axle 48 . A roller follower 13 is located between the locking end 14 and the hinge end 16 , which interfaces with the first camshaft lobe 92 A to translate rotary motion of the first camshaft lobe 92 A to linear motion of the first engine valve 96 A when the inner lever 12 is locked to the outer lever 20 . The roller follower 13 could also be replaced by an optional slider interface. The outer lever 20 includes a valve end 22 with a valve interface 23 , and a pivot end 24 that houses the first locking part 30 A.

The first switchable lever 10 A utilizes lost motion springs 18 that have a first end connected to the inner lever 12 and a second end connected to the inner lever. The lost motion springs 18 primarily function when the inner lever 12 is unlocked from the outer lever 20 . During this unlocked state, the lost motion springs 18 provide a force that can: 1). act upon the inner lever 12 to provide a controlled motion of the inner lever 12 to prevent separation with the first camshaft lobe 92 A at a maximum unlocked mode speed, and 2). act upon the outer lever 20 to prevent a pump-up or extended length condition of the first pivot element 94 A, which could hinder the switching function of the first switchable lever 10 A.

The first locking part 30 A includes a shuttle pin 32 , a first return spring 36 A, a retaining cap 38 , and a locking pin 40 . Several other forms of the first locking part 30 A are possible that include additional components or a reduced number of components. The shuttle pin 32 moves within a first bore 26 that is arranged at the pivot end 24 of the outer lever 20 . The first bore 26 , and, thus, the shuttle pin 32 are arranged transverse to the switchable lever 10 A. The term “transverse” is meant to describe a path or direction that runs across the switchable lever; stated otherwise, a first axis AX 1 of the first bore 26 is parallel to a third axis AX 3 of the pivot axle 48 (see FIG. 6A ).

The locking pin 40 moves within a second bore 28 that is orthogonal to the first bore 26 , meaning that a second axis AX 2 of the second bore 28 can be perpendicular to the first axis AX 1 without being coplanar. The locking pin 40 moves within the second bore 28 when the shuttle pin 32 moves within the first bore 26 via actuation by the rotary actuator 50 . Stated otherwise, movement of the shuttle pin 32 , caused by the rotary actuator 50 , along the first axis AX 1 that is transverse to the first switchable lever 10 A, induces movement of the locking pin 40 along the second axis AX 2 that is orthogonal to the first axis AX 1 . Translation of shuttle pin movement to locking pin movement, which could also be described as translation of transverse movement to longitudinal movement, is accomplished by a cam-and-follower type arrangement, as shown in FIGS. 3, 6A and 6B . The shuttle pin 35 is configured with a first flat 33 that slidably engages a second flat 41 of the locking pin 40 . An actuation groove 34 is formed within the first flat 33 of the shuttle pin 35 that receives a protrusion 42 that extends from the second flat 41 of the locking pin 40 . The actuation groove 34 includes a straight portion 43 and a ramp portion 37 that, depending on a direction of travel of the shuttle pin 32 , either pushes or pulls the locking pin 40 into a first locked position or a second unlocked position, respectively. Many other design means for translating motion from the shuttle pin 32 to the locking pin 40 are also possible.

With reference to FIG. 6A and the first switchable lever 10 A on the left side, the first locked position of the first locking part 30 A is shown, in which the first return spring 36 A urges the shuttle pin 32 to a right-most stop position. In the first locked position, the protrusion 42 of the locking pin 40 is located at a beginning of the ramp portion 37 (or an end of the straight portion 43 ) of the actuation groove 34 . In the first locked position, the rotary actuator 50 is in a position in which it allows the shuttle pin 32 to remain at its right-most stop position. In the first locked position, the locking in 40 extends into the inner lever 12 , such that a latching flat 44 of the locking pin 40 is proximate to the locking surface 15 of the inner lever 12 (see FIGS. 4A and 4B ). The latching flat 44 is configured to engage the locking surface 15 during a valve lift event. The components and positions of the rotary actuator 50 will be further described in the paragraphs below.

With reference to FIG. 6B and the first switchable lever 10 A on the left side, the second unlocked position of the first locking part 30 A is shown, in which the shuttle pin 32 is displaced to the left within the first bore 26 by the rotary actuator 50 . In the second unlocked position, the protrusion 42 of the locking pin 40 is engaged with the ramp portion 37 of the actuation groove 34 , causing the shuttle pin 32 to pull or retract the locking pin 40 from the inner lever 12 .

The rotary actuator 50 can have many different forms and configurations. The term “actuator” is used throughout the specification and claims and is intended to define a component, or assembly of components that actuates the first and/or second switchable levers 10 A, 10 B, or any other switchable valve train component.

The rotary actuator 50 includes a rotary platform 58 that is rotationally actuated about a rotational axis RA by a solenoid 52 . The rotational axis RA of the rotary actuator 50 is non-concentric to the first axis AX 1 of the first bore 26 , and, therefore, also non-concentric to a central axis of the shuttle pin 32 that can be engaged by the rotary actuator 50 . Control of the rotary actuator 50 (energizing and timing thereof) can be accomplished by an electronic controller 85 that can communicate electronically with the actuator 50 . A connector post 54 can connect the rotary platform 58 to the solenoid 52 via a post aperture 56 arranged in the rotary platform 58 . The rotary platform 58 can include a first finger 60 A, a second finger 60 B and a tension spring 76 . The first finger 60 A and the second finger 60 B are pivotably mounted to the rotary platform 58 at respective first and second pivoting connections 80 A, 80 B. The first and second pivoting connections 80 A, 80 B can be facilitated by a pressed-in or staked cylindrical pin, however, any design that suits the function of a pivoting connection is possible.

With specific reference to FIGS. 6A and 6B , upon rotation of the rotary platform 58 around the rotational axis RA in a first rotational direction RD 1 or a second rotational direction RD 2 , the first and second fingers 60 A, 60 B are either moved closer to the first and second switchable levers 10 A, 10 B or retracted so that they are further away. Stated more specifically, upon rotation in a first rotational direction RD 1 , the following can occur: 1). the first finger 60 A engages the first locking part 30 A such that the first locking part 30 A is displaced in a first direction D 1 by a first end 62 A of the first finger 60 A; and, 2). the second finger 60 B engages the second locking part 30 B such that the second locking part 30 B is displaced in a second direction D 2 by a first end 62 B of the second finger 60 B. Upon rotation in a second rotational direction RD 2 , the following can occur: 1). the first finger 60 A moves away from the first locking part 30 A such that the first locking part 30 A moves in the second direction D 2 ; this movement can be assisted by the first return spring 36 A arranged within the first locking part 30 A, or by some other means; and, 2). the second finger 60 B moves away from the second locking part 30 B such that the second locking part 30 B moves in the first direction D 1 ; this movement can also be assisted by a second return spring 36 B arranged within the second locking part 30 B.

Although not shown in the Figures, at least a portion of the first and second fingers 60 A, 60 B could be resiliently configured to eliminate or reduce any lash or space between the fingers 60 A, 60 B and the respective first and second locking parts 30 A, 30 B while in the first locked position. In an example embodiment, the first end 62 A of the first finger 60 A could be spring-loaded, and the first end 62 B of the second finger 60 B could be spring-loaded, such that when the fingers 60 A, 60 B are retracted to achieve the first locked position, each of the respective first ends 62 A, 62 B remains engaged with the respective first and second locking parts 30 A, 30 B.

Each of the motion paths of the first and second fingers 60 A, 60 B is guided by respective first and second motion guides 70 A, 70 B that can be received by or formed within a cylinder head 90 of an IC engine or any other receiving structure. The tension spring 76 (at least one) is connected to the first and second fingers 60 A, 60 B to provide a guiding force that induces a sliding connection between the first and second fingers 60 A, 60 B and their respective first and second motion guides 70 A, 70 B; more specifically, this sliding connection occurs between a first guide surface 64 A of the first finger 60 A and a first outer surface 72 A of the first motion guide 70 A; and, a second guide surface 64 B of the second finger 60 B and a second outer surface 72 B of the second motion guide 70 B.

Rotation of the rotary actuator 50 in either first or second rotational directions RD 1 , RD 2 to any rotational angle AN achieves continuously variable effective actuation lengths EL of the rotary actuator. The rotational angle AN is defined as an angle between a horizontal datum line D and a connector line C that connects the centers of the first and second pivoting connections 80 A, 80 B. Effective actuation lengths EL are defined as a distance from the rotation axis RA of the rotary actuator 50 to an outermost surface of one or both of the first and second fingers 60 A, 60 B that contacts respective one or both of the first and second locking parts 30 A, 30 B.

As shown in FIG. 6A , a first effective actuation length EL 1 A is achieved for the first finger 60 A when the rotary actuator 50 is at a first rotational angle AN 1 of 90 degrees. Likewise, a first effective actuation length EL 1 B is achieved for the second finger 60 B when the rotary actuator 50 is at the first rotational angle AN 1 of 90 degrees. As shown, the first effective actuation lengths EL 1 A, EL 1 B for the respective first and second fingers 60 A, 60 B are equal, however, the rotary actuator 50 and first and second fingers 60 A, 60 B could be designed to provide different effective actuation lengths (EL 1 A≠EL 1 B) for each finger at any rotational angle of the rotary actuator 50 .

With reference to FIG. 6B , a second effective actuation length EL 2 A is achieved for the first finger 60 A when the rotary actuator 50 is at a second rotational angle AN 2 of zero degrees. Likewise, a second effective actuation length EL 2 B is achieved for the second finger 60 B when the rotary actuator is at a rotational angle AN 1 of zero degrees. In the example embodiment shown in the Figures, the second effective actuation lengths EL 2 A, EL 2 B are longer than the first effective actuation lengths EL 1 A, EL 1 B.

It is also possible to design the rotary actuator 50 and corresponding first and second levers 10 A, 10 B such that an increased effective actuation length EL (such as EL 2 A, EL 2 B) provides for the first locked position, and a decreased effective actuation length EL (such EL 1 A, EL 1 B) provides for the second unlocked position.

FIGS. 6A and 6B show two discrete rotational angles AN 1 , AN 2 of the rotary actuator 50 . As the rotary actuator 50 moves from the first rotational angle AN 1 to the second rotational angle AN 2 , an effective actuation length EL for the first and second fingers 60 A, 60 B continuously increases in length. Likewise, as the actuator moves from the second rotational angle AN 2 to the first rotational angle AN 1 , an effective actuation length for the first and second fingers 60 A, 60 B continuously decreases in length. Stated otherwise, as the rotary actuator 50 rotates from the first rotational angle AN 1 to the second rotational angle AN 2 , it yields all effective actuation lengths that reside between the first and second effective actuation lengths EL 1 A, EL 1 B for the first finger 60 A, and likewise, any effective actuation length EL that resides between the first and second effective actuation lengths EL 2 A, EL 2 B for the second finger 60 B. Stated yet in another way, as the rotary actuator 50 rotates in the first rotational direction RD 1 , the first ends 62 A, 62 B of the respective first and second fingers 60 A, 60 B move away from the rotational axis RA; additionally, as the rotary actuator 50 rotates in the second rotational direction RD 2 , the first ends 62 A, 62 B of the respective first and second fingers 60 A, 60 B are retracted, or move closer to the rotational axis RA.

FIGS. 4A, 6A show the first locked position of the first switchable lever 10 A and its respective first locking part 30 A, achieved by the first rotational angle AN 1 of the rotary actuator 50 ; and FIGS. 4B, 6B show the second unlocked position of the first switchable lever 10 A and its respective first locking part 30 A, achieved by the second rotational angle AN 2 of the rotary actuator 50 . The first locked position can enable a first valve lift mode and the second unlocked position can enable a second valve lift mode. The first valve lift mode can be a full-valve-lift mode, and the second valve lift mode can be a no-valve-lift mode. The no-valve-lift mode can be described as a valve deactivation mode.

From the previously described arrangement and operation of the switchable valve train system 100 , the following describes a method of actuating a switchable valve train component. Although the method is presented as a sequence of steps for clarity, no order should be inferred from the sequence unless explicitly stated.

A first step includes providing: a). a switchable valve train component having a first component, a second component, and a locking part that selectively locks the first component to the second component; and, b). a rotary actuator that rotates about the rotational axis to actuate the locking part.

A second step includes rotating the rotary actuator to continuously decrease an effective actuation length of the rotary actuator to move the locking part to a first locked position; and,

A third step includes rotating the rotary actuator to continuously increase an effective actuation length of the rotary actuator to move the locking part to a second unlocked position.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.