Not Applicable.
Conventional two-way clutches can include a driven member and a drive member that may bi-directionally displace with or relative to the driven member. In some applications, a two-way clutch can selectively transition between modes where the driven member and the drive member move in unison, and where the drive member is allowed to move relative to the driven member.
In some aspects, the present disclosure provides a mechanical cam phasing system for an internal combustion engine having a crankshaft and a camshaft. The mechanical cam phasing system including a stator rotationally coupled to the crankshaft and having a first mating surface, a cradle rotor rotationally coupled to the camshaft and having a second mating surface, a first locking mechanism having a first locking feature and a second locking feature, and a cage. The mechanical cam phasing system further including a second locking mechanism rotationally coupled to the cradle rotor for rotation therewith and selectively moveable between a locking state and a phasing state. In the locking state, a clearance is provided between the cradle rotor and the cage to allow the cradle rotor to rotate relative to the cage and lock the first locking feature or the second locking feature by compression between the first mating surface and the second mating surface. Where in the phasing state, the clearance between the cradle rotor and the cage is reduced to ensure rotational coupling between the cradle rotor and the cage in at least one direction. The second locking mechanism is configured to transition between the locking state and the phasing state in response to an input displacement applied thereto. The rotational coupling between the cradle rotor and the cage in the phasing state is configured to displace the first locking feature or the second locking feature relative to the cradle rotor and enable the cradle rotor to rotate relative to the stator.
In some aspects, the present disclosure provides a mechanical cam phasing system for an internal combustion engine having a crankshaft and a camshaft. The mechanical cam phasing system including a stator rotationally coupled to the crankshaft, a cradle rotor rotationally coupled to the camshaft, a locking assembly including a first locking feature and a second locking feature, a cage, and an actuation assembly. The actuation assembly including a slot tube rotationally coupled to the cage through one or more compliance members and including a slot extending axially along a portion thereof. The slot defines a locking region and one or more phasing regions axially separated from the locking region. The actuation assembly further includes a plunger slidably received within the slot tube, a pin extending through the plunger and the slot in the slot tube, the pin being rotationally coupled to the cradle rotor for rotation therewith, and a solenoid configured to selectively displace the plunger and thereby the pin along the slot of the slot tube. The solenoid is configured to selectively displace the pin from the locking region to one of the one or more phasing regions, which, in turn, transitions a rotational relationship between the stator and the cradle rotor from a locked state where relative rotation is inhibited to an unlocked state where relative rotation in a desired direction is enabled.
In some aspects, the present disclosure provides a method for adjusting a rotational relationship between a camshaft and a crankshaft on an internal combustion engine. The camshaft is coupled to a cradle rotor for rotation therewith and the crankshaft is coupled to a stator for rotation therewith. The method includes providing a predetermined interference to a locking assembly via engagement with a cage. The predetermined interference displaces the locking assembly out of engagement with at least one of the stator and the cradle rotor, when the cradle rotor is in an unloaded state. The method further includes actuating a solenoid to a desired position, in response to actuating the solenoid to the desired position, providing a force between the cradle rotor and the cage in order to maintain the cage in engagement with the locking assembly and bias the locking assembly relative to the cradle rotor in one direction, and the biasing of the locking assembly relative to the cradle rotor adjusting the rotational relationship between the cradle rotor and the stator in the one direction.
The foregoing and other aspects and advantages of the disclosure will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred configuration of the disclosure. Such configuration does not necessarily represent the full scope of the disclosure, however, and reference is made therefore to the claims and herein for interpreting the scope of the disclosure.
The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings.
The use herein of the term “axial” and variations thereof refers to a direction that extends generally along an axis of symmetry, a central axis, or an elongate direction of a particular component or system. For example, axially extending features of a component may be features that extend generally along a direction that is parallel to an axis of symmetry or an elongate direction of that component. Similarly, the use herein of the term “radial” and variations thereof refers to directions that are generally perpendicular to a corresponding axial direction. For example, a radially extending structure of a component may generally extend at least partly along a direction that is perpendicular to a longitudinal or central axis of that component. The use herein of the term “circumferential” and variations thereof refers to a direction that extends generally around a circumference or periphery of an object, around an axis of symmetry, around a central axis, or around an elongate direction of a particular component or system.
Generally, the locking mechanism 106 may be arranged between the stator 102 and the cradle rotor 104. The locking mechanism 106 may be configured to selectively allow relative motion between the stator 102 and the cradle rotor 104. For example, the locking mechanism 106 may be movable between a locked position and an unlocked position. In the unlocked position, the locking mechanism 106 may allow the cradle rotor 104 to displace relative to the stator 102 in a desired direction. In the locked state, the locking mechanism 106 may inhibit relative motion between the stator 102 and the cradle rotor 104 in at least one direction.
In the illustrated non-limiting example, the stator 102 may include a first mating surface 110 arranged adjacent to the locking mechanism 106. The cradle rotor 104 may include a second mating surface 112 arranged adjacent to the locking mechanism 106. In the illustrated non-limiting example, the locking mechanism 106 may be arranged between the first mating surface 110 and the second mating surface 112. The locking mechanism 106 may include a first locking feature 114 and a second locking feature 116 biased apart from one another by a biasing element 118. In some non-limiting examples, the first and second locking features 114 and 116 may be in the form of bearings. In some non-limiting examples, the first and second locking features 114 and 116 may be in the form of roller bearings. In some non-limiting examples, the first and second locking features 114 and 116 may take any form configured to conform to a cavity between the first mating surface 110 and the second mating surface 112 (e.g., wedges).
In operation, the cradle rotor 104 may be subjected to an outside force that applies a load onto the locking mechanism 106. For example, a component of the device to which the cradle rotor 104 is coupled may exert the outside force on the cradle rotor 104. In some non-limiting examples, the outside force may occur in more than one direction. In some non-limiting examples, the outside force applied to the cradle rotor 104 may cyclically vary between a first direction and a second direction.
In some non-limiting examples, when the outside force is exerted on the cradle rotor 104, the corresponding load applied to the locking mechanism 106 can compress either the first locking feature 114 or the second locking feature 116, depending on the direction of the outside force, between the stator 102 and the cradle rotor 104. This compression applied to the locking mechanism 106 may substantially prevent either the first locking feature 114 or the second locking feature 116 from being transitioned between the locked and unlocked positions. That is, the compression of the locking mechanism 106 between the stator 102 and the cradle rotor 104 may effectively “lock” the locking mechanism 106 in a direction that corresponds with the direction of the outside force and substantially prevent the relative rotation between the cradle rotor 104 and the stator 102 in this direction. Thus, for certain operating conditions, the outside force applied to the cradle rotor 104 may place the locking mechanism 106 in a loaded state in which the cradle rotor 104 is prevented from rotating relative to the stator 102 in a direction that corresponds with the outside force.
In general, the cage 108 may provide a predetermined interference that may be applied to the locking mechanism 106 to combat the undesired “locking” thereof in the loaded state and enable relative rotation between the stator 102 and the cradle rotor 104 with minimal input force. In some non-limiting examples, the cage 108 may be placed in engagement with the locking mechanism 106, such that the cage 108 provides a predetermined interference to the locking mechanism 106. For example, the cage 108 may be designed to provide the predetermined interference on the locking mechanism 106, when the locking mechanism 106 is in an unloaded state (i.e., the outside force is not applied to the cradle rotor 104). In some non-limiting examples, the predetermined interference provided by the cage 108 may displace the locking mechanism 106 away from at least one of the stator 102 and the cradle rotor 104 such that a gap exists therebetween. In some non-limiting examples, the predetermined interference provided by the cage 108 may displace the locking mechanism 106 away from both of the stator 102 and the cradle rotor 104 such that a gap exists therebetween.
In some non-limiting examples, the two-way clutch 100 may be applied in a rotating two-way clutch application. For example, the two-way clutch 100 may be applied in a mechanical cam phasing application, where the stator 102 may be rotatably coupled to a crankshaft on an internal combustion engine and the cradle rotor 104 may be rotatably coupled to a camshaft on an internal combustion engine.
One non-limiting example of the operation of the two-way clutch 100 in a mechanical cam phasing application will be described with reference to
During operation, an outside force may be applied to the cradle rotor 104 in a first direction, as illustrated in
During operation, once the outside force in the first direction is removed, the outside force applied to the cradle rotor 104 may transition to a second direction as illustrated in
As illustrated in
In general, with the predetermined interference provided on the first locking mechanism 106 by the cage 108, a predetermined amount of relative motion between the cradle rotor 104 and the cage 108 may be required for the first locking mechanism 106 to lock (i.e., prevent relative rotation between the stator 102 and the cradle rotor 104). For example, with the cage 108 holding the first locking feature 114 off of at least one of the first mating surface 110 and the second mating surface 112, the cradle rotor 104 must be allowed to move at least a predetermined amount relative to the cage 108 to ensure that the first locking feature 114 is loaded and compressed between the first mating surface 110 and the second mating surface 112. However, if this relative motion between the cradle rotor 104 and the cage 108 is prevented in a desired direction via the second locking mechanism 202, the first locking mechanism 106 may be prevented from locking in a desired direction (i.e., a selective one of the first locking feature 114 and the second locking feature 116 may remain unlocked) and thereby force the cage 108 and the cradle rotor 104 to rotate in the desired direction relative to the stator 102.
To achieve this functionality, the second locking mechanism 202 may by coupled to the cradle rotor 104 for rotation therewith. The second locking mechanism 202 may be selectively movable between a disengaged state (
In some non-limiting examples, the two-way clutch 200 may be applied in a rotating two-way clutch application. For example, the two-way clutch 200 may be applied in a mechanical cam phasing application, where the stator 102 may be rotatably coupled to a crankshaft on an internal combustion engine and the cradle rotor 104 may be rotatably coupled to a camshaft on an internal combustion engine.
One non-limiting example of the operation of the two-way clutch 200 in a mechanical cam phasing application will be described with reference to
It should be appreciated that the opposite process may occur in response to an outside force applied to the cradle rotor 104 in a second direction (e.g., counterclockwise) opposite to the first direction. That is, the second locking feature 116 may be compressed between the first mating surface 110 and the second mating surface 112 to “lock” the second locking feature 116 and prevent rotation of the cradle rotor 104 in the second direction relative to the stator 102.
At a time when the outside force in the first direction is applied to the cradle rotor 104, the second locking mechanism 202 may transition from the disengaged state to the engaged state (
It should be appreciated that the opposite process may occur for desired relative rotation between the cradle rotor 104 and the stator 102 in the first direction. That is, the second locking mechanism 202 may transition to the engaged state and force the first locking feature 114 to remain unlocked as the outside force transitions from the second direction to the first direction. As the outside force in the first direction is applied to the cradle rotor 104, the second locking mechanism 202 may prevent relative rotation between the cradle rotor 104 and the cage 108 in the first direction, and maintain the cage 108 in engagement with the first locking feature 114 to hold the first locking feature 114 in an “unlocked” state. Thus, as the outside force in the first direction is applied to the cradle rotor 104, the cradle rotor 104 and the cage 108 are forced to rotate together in the first direction relative to the stator 102, thereby phasing the rotational relationship between the camshaft and the crankshaft.
The use of the second locking mechanism 202 may be implemented in a mechanical cam phasing system to provide selective phasing between a camshaft and a crankshaft without a need for high-cost actuation systems to facilitate the phasing. For example, a single, low-force actuator may be used to facilitate the selective phasing between the camshaft and the crankshaft, which simplifies the actuation and substantially reduces a cost of the cam phasing system when compared to conventional mechanical, hydraulic, and electronic cam phasing systems. In addition, this simplified actuation may enable the mechanical cam phasing system to be operable with a reduced number of components when compared to conventional cam phasing systems.
In general, the stator 302, the cradle rotor 304, the cage 308, and the actuation assembly 312 may be arranged concentrically about a common axis A. For the description herein of features relating to or included within the mechanical cam phasing system 300, the use of the terms “axial,” “radial,” and “circumferential” (and variations thereof) are based on a reference axis corresponding to the axis A.
In the illustrated non-limiting example, the cradle rotor 304 may be arranged at least partially within the stator 302 and may be rotationally coupled to a camshaft on an internal combustion engine for rotation therewith. In the illustrated non-limiting example, each of the first locking assemblies 306 may include a first locking feature 320, a second locking feature 322, and a biasing element 324. The biasing element 324 may be arranged between and in engagement with corresponding pairs of the first and second locking features 320 and 322, thereby biasing the first and second locking features 322 and 324 away from one another. In some non-limiting examples, the biasing elements 324 may be in the form of a spring. In some non-limiting examples, the biasing elements 324 may be in the form of any viable mechanical linkage capable of forcing the first locking feature 320 and the second locking feature 322 away from one another, as desired. In some non-limiting examples, each of the first locking assemblies 306 may include one or more biasing elements 324. In some non-limiting examples, the first locking feature 320 and the second locking feature 322 may be in the form of roller bearings. In some non-limiting examples, the first locking feature 320 and the second locking feature 322 may be in the form of a wedge.
In the illustrated non-limiting example, the cage 308 may include a cage ring 326, a plurality of cage protrusions 328, a plurality of cage arms 330, and a central cage hub 332. The cage ring 326 may be arranged radially between the cradle rotor 304 and the stator 302 (i.e., between the cradle rotor 304 and the radially inner surface of the stator ring 316). A plurality of cage protrusions 328 may extend axially away from the cage ring 326 and toward the first locking assemblies 306 for engagement therewith. In the illustrated non-limiting example, the cage protrusions 328 are arranged circumferentially around the cage ring 326. In the illustrated non-limiting example, each circumferentially adjacent pair of the cage protrusions 328 includes a corresponding one of the plurality of first locking assemblies 306 arranged therebetween. That is, one of the cage protrusions 328 may engage the first locking feature 320 of a corresponding one of the first locking assemblies 306, and a circumferentially adjacent cage protrusion 328 may engage the second locking feature 322 of the corresponding one of the first locking assemblies 306. The engagement by the cage protrusions 328 on the first locking features 320 and the second locking features 322 may provide a predetermined interference thereto that displaces the first locking feature 320 and the second locking feature 322 out of engagement with at least one of the stator 302 and the cradle rotor 304, when the cradle rotor 304 is in an unloaded state (i.e., no outside forces applied to the cradle rotor 304). As will be described herein, the actuation assembly 312 may be configured to selectively maintain the predetermined interference on either the first locking feature 320 or the second locking feature 322 by selectively rotationally coupling the cradle rotor 304 and the cage 308, which, in turn, allows relative rotation between stator 302 and the cradle rotor 304 in a desired direction with minimal input force.
In the illustrated non-limiting example, each of the cage arms 330 extend radially between the central cage hub 332 and the radially inner surface of the cage ring 326, and arranged circumferentially about the cage 308. In some non-limiting examples, the cage 308 includes four cage arms 330. In some non-limiting examples, the cage 308 includes more or less than four cage arms 330. The central cage hub 332 includes a cage aperture 334 extending axially therethrough.
With reference to
Each of the cage slots 346 may receive a corresponding one of the cage arms 330 therein. The cage slots 346 and the cage arms 330 may be designed to ensure that when the cage arms 330 is received within the cage slots 346, the cage arms 330 are provided with sufficient lateral, or circumferential, clearance to not engage any portion of the cage slots 346 during operation.
In the illustrated non-limiting example, each of the first locking assemblies 306 is arranged between a first mating surface 345 arranged on the stator 302 and a second mating surface 347 arranged on the cradle rotor 304. In the illustrated non-limiting example, the first mating surface 345 may be the radially inward surface of the stator ring 316, and the second mating surface 347 may be defined by the outer periphery of the cradle rotor 304.
In the illustrated non-limiting example of
In the illustrated non-limiting example, the slot tube 348 may include a plurality of tabs 358 and a pair of opposing slots 362. In some non-limiting examples, the slot tube 348 may include more than two slots 362. The plurality of tabs 358 extend axially from an upper surface of the slot tube 348, and form tube slots 360 in between circumferentially adjacent tabs 358 that align with the cage slots 346 in the cradle rotor 304. Each of the tube slots 360 is configured to receive a corresponding one of the cage arms 330 to rotationally key, or couple, the slot tube 348 to the cage 308.
Each of the slots 362 extends radially through and axially along a portion of the slot tube 348. In general, the slots 362 may each define a locking state and one or more phasing states for operation of the cam phasing system 300. For example, the locking state may correspond with a locking region defined along the slots 362, which inhibits relative rotation between the cradle rotor 304 and the stator 302. The one or more phasing states may correspond with one or more phasing regions defined along the slots 362 to enable or allow relative rotation between the cradle rotor 304 and the stator 302. In some non-limiting examples, the slots 362 may define three regions or axial locations where the pin 354 may be displaced to by the solenoid 356 to facilitate different the different operating modes, or states, of the cam phasing system 300. For example, the slots 362 may include a locking region, a forward phasing region (advance), and a backward phasing region (retard). Switching between the locking region and either the forward phasing region or the backward phasing region may adjust a clearance between the cradle rotor 304 and the cage 308. That is, a clearance between the pin 354 and the slots 362 formed in the slot tube 348 may be adjusted by switching, or displacing the pin 354, between the locking region and either the forward phasing region or the backward phasing region. In some non-limiting examples, displacing the pin 354 to the forward phasing region or the backward phasing region may reduce a clearance between the pin 354 and the slots 362 to ensure that the pin 354 engages the slots 362 and allow the cage 308 to displace either the first locking features 320 or the second locking features 322 (depending on whether forward or backward phasing is desired) relative to the stator 304, which enables the cradle rotor 304 to harvest outside forces in a desired direction and rotate relative to the stator 302.
For example, when the pin 354 is in the locking region, the slots 362 may define enough rotational clearance relative to the pin 354 to enable the cradle rotor 304 to rotate relative to the cage 308 an amount sufficient to compress and lock the first locking feature 320 or the second locking feature 322 (depending on the direction of an outside force applied to the cradle rotor 304) and provide bi-directional locking between the cradle rotor 304 and the stator 302. When the pin 354 is displaced to the forward phasing region, the slots 362 may define a geometry that provides sufficient clearance relative to the pin 354 in a first direction to prevent relative rotation between the cradle rotor 304 and the stator 302 in the first direction and that ensures engagement between the pin 354 and the slots 362, when an outside force is applied to the cradle rotor 304 in a second direction. The engagement between the pin 354 and the slots 362 may unlock, for example, the first locking feature 320 and the outside force applied to the cradle rotor 304 in the second direction may be allowed to rotate the cradle rotor 304 relative to the stator 302. When the pin 354 is displaced to the backward phasing region, the slots 362 may define a geometry that provides sufficient clearance relative to the pin 354 in a second direction to prevent relative rotation between the cradle rotor 304 and the stator 302 in the second direction and that ensures engagement between the pin 354 and the slots 362, an outside force is applied to the cradle rotor 304 in the first direction. The engagement between the pin 354 and the slots 362 may unlock, for example, the second locking feature 322 and the outside force in the first direction applied to the cradle rotor 304 may be allowed to rotate the cradle rotor 304 relative to the stator 302.
With specific reference to
In the illustrated non-limiting example, the clearance portion 366 and ramped clearance portion 371 of the slot 362 may define the greatest lateral width along the slot 362, when compared to the first ramped portion 370 and the second ramped portion 372. The clearance portion 366 and the ramped clearance portion 371 may define locking regions for the pin 354 along the slot 362. The first ramped portion 370 extends laterally inward from a first side 374 of the slot 362, and defines a ramp that decreases in laterally-inward protrusion as the ramp extends axially away from a first peak 375 arranged at a location axially adjacent to the clearance portion 366. The second ramped portion 372 extends laterally inward from a second side 376 of the slot 362, and defines a ramp that decreases in laterally-inward protrusion as the ramp extends axially away from a second peak 378 arranged at a location axially away from the clearance portion 366 (i.e., the clearance portion 366 may be arranged at one end of the slot 362 and the second peak 378 may be arranged adjacent to an axially opposing end of the slot 362). The first ramped portion 370 and the second ramped portion 372 may define the forward phasing region and the backward phasing region for the pin 354 along the slot 362. The ramped clearance portion 371 may be arranged axially between the first ramped portion 370 and second ramped portion 372. In the illustrated non-limiting example, the first ramped portion 370 and the second ramped portion 372 taper axially toward one another. In some non-limiting examples, the orientation and arrangement of the clearance portion 366 and the ramped portion 368 may vary. In general, the use of the slots 362, in combination with the use of a spring, enable a single, unidirectional solenoid to actuate the mechanical cam phasing system 300.
In some non-limiting examples, the slots 362 may define an alternative geometry that enables the three regions of operation for the cam phasing system 300. For example,
In the neutral position 379 illustrated in
Alternatively, as the pin 354 is displaced axially away from the neutral position 379 to, for example, the backward phasing region 383, the pin 354 may be displaced into closer proximity to, or into engagement with, the second side 376 of the slot 362 due to the angled, or helical, arrangement of the slot 362 relative to the axis A. In this way, for example, the geometry of the slot 362 may ensure that the pin 354 engages the second side 376 of the slot 362 when the cradle rotor 304 is subjected to outside forces in a second direction (e.g., counterclockwise). While the angled arrangement of the slot 362 may bring the pin 354 into closer proximity to, or into engagement with, the second side 376 of the slot 362 in the backward phasing region 383, the pin 354 may maintain at least the clearance 377 defined at the neutral position 379 between the pin 354 and the first side 374. This may enable the cradle rotor 304 to displace relative to the stator 302, without the pin 354 engaging the first side 374 of the slot 362, to allow, for example, the first locking feature 320 to lock via compression between the first mating surface 345 of the stator 302 and the second mating surface 347 of the cradle rotor 304.
In any configuration, when assembled, the pin 354 may extend laterally through the pin aperture 355 in the plunger 350, the slots 362 of the slot tube 348, and at least partially into the pin slots 344 of the cradle rotor. For example, opposing ends of the pin 354 may extend into the pin slots 344 to rotationally couple the plunger 350 and the pin 354 to the cradle rotor 304 for rotation therewith.
In the illustrated non-limiting example, the solenoid 356 may be arranged externally from the stator 302. In some non-limiting examples, the solenoid 356 may be arranged within the stator 302 as will be described herein. The solenoid 356 may include an armature 380 that is selectively displaceable to a desired position in response to a current applied to a wire coil 382. The armature 380 may be coupled to the plunger 350 to selectively displace the plunger 350 axially along the slot tube 348 against the force of the spring 352, which displaces the pin 354 axially along the slots 362 to a desired position (see, e.g.,
General operation of the cam phasing system 300 will be described with reference to
When it is desired to allow the cradle rotor 304 to rotate relative to the stator 302 in a second direction (e.g., counterclockwise), the solenoid 356 may displace the pin 354 to be axially aligned with the first ramped portion 370. The reduced clearance between the pin 354 and the first ramped portion 370 may ensure that the pin 354 engages the first side 374 of the slot 362 in response to a cam torque pulse applied to the cradle rotor 304 in a second direction (e.g., counterclockwise) via the rotational coupling between the pin 354 and the cradle rotor 304. Once the pin 354 engages the first side 374 of the slot 362, relative motion between the cradle rotor 304 and the cage 308 is prevented in the second direction via the rotational coupling of the cage 308 and the slot tube 348. In addition, the cage 308 is maintained in engagement with the second locking feature 322 and applies the predetermined interference thereto, which keeps the second locking feature 322 unlocked. In this way, when the cam torque pulse rotates the cradle rotor 304 in the second direction, the cage 308 and cradle rotor 304 are allowed to rotate together relative to the stator 302.
Conversely, when it is desired to allow the cradle rotor to rotate relative to the stator 302 in a first direction (e.g., clockwise), the solenoid may displace the pin 354 to by axially aligned with the second ramped portion 372. The reduced clearance between the pin 354 and the second ramped portion 372 may ensure that the pin 354 engages the second side 376 of the slot 362 in response to a cam torque pulse applied to the cradle rotor 304 in a first direction (e.g., clockwise). Once the pin 354 engages the second side 376 of the slot 362, relative motion between the cradle rotor 304 and the cage 308 is prevented in the first direction via the rotational coupling of the cage 308 and the slot tube 348. In addition, the cage 308 is maintained in engagement with the first locking feature 320 and applies the predetermined interference thereto, which keeps the first locking feature unlocked. In this way, when the cam torque pulse rotates the cradle rotor 304 in the first direction, the cage 308 and the cradle rotor 304 are allowed to rotate relative to the stator 302.
During operation, when it is desired to transition from an unlocked state to a locked state, the pin 354 may be displaced by the solenoid 356 from one of the first ramped portion 370 and the second ramped portion 372 to axially align with the ramped clearance portion 371. Similar to the clearance portion 366, the ramped clearance portion 371 may allow the cradle rotor 304 to move relative to the cage 308 a predetermined amount sufficient to enable either the first locking feature 320 or the second locking feature 322 to lock via compression between the first mating surface 345 of the stator 302 and the second mating surface 347 of the cradle rotor 304, depending on the direction of cam torque pulse applied to the cradle rotor 304. In some non-limiting examples, the clearance portion 366 may be a “default” locked position for the pin 354 that ensures the system is locked, when the solenoid is de-energized (e.g., after engine shutdown).
With the ramped clearance portion 371 being axially between the first ramped portion 370 and the second ramped portion 372, the ramped clearance portion 371 may be a closer option for locking the system during operation, when compared to the clearance portion 366. Thus, during operation, the ramped clearance portion 371 may be used to facilitate the locking of the system, and the pin 354 may be selectively displaced to axially align with a portion of the first ramped portion 370 or the second ramped portion 372 to enable unlocking in a desired direction (i.e., relative rotation between the cradle rotor 304 and the stator 302 in a desired direction.
In the illustrated non-limiting example, the ramped profiled defined by the first ramped portion 370 and the second ramped portion 372 may enable a proportional control of the locking and unlocking between the cradle rotor 304 and the stator 302. For example, when the pin 354 is aligned axially closer to either the first peak 375 or the second peak 378, the relative rotation between the cradle rotor 304 and the stator 302 may be fully unlocked in a desired direction. If the pin 354 is aligned axially with a region of the first ramped portion 370 or the second ramped portion 372 away from the peaks 375, 378, the incrementally increased clearance between the pin 354 and the respective one of the first side 374 and the second side 376 may enable a partially unlocked state. That is, the cradle rotor 304 may be allowed to rotate relative to the stator 302 a predetermined amount prior to the cradle rotor 304 fully engaging and locking one of the first locking feature 320 and the second locking feature 322 (depending of the direction of the cam torque pulse). In this partially unlocked state, the relative motion between the cradle rotor 304 and the stator 302 may be slowed down, when compared to the fully unlocked state, which is beneficial when trying to control the mechanical cam phasing system 300 during smaller, fine phasing adjustments.
In some non-limiting examples, the cam phasing system 300 may include a compliance member rotationally coupled between the cage 308 and the slot tube 348 (and the slots 362) that enables proportion control of the relative rotation speed between the cradle rotor 304 and the stator 302, by controlling the amount of relative rotation that occurs between these parts when outside forces are applied to the cradle rotor 304. For example, as illustrated in
For example, if the cradle rotor 304 is subjected to an outside force in a direction while the pin 354 is actuated to the forward phasing region or the backward phasing region, the compliance members 384 may control the amount of relative rotation between the cradle rotor 304 and the stator 302 that occurs prior to locking. That is, the pin 354 may engage the slot 362 and load the cage 308 through the compliance members 384 (i.e., hold the cage 308 in engagement with one of the first locking features 320 and the second locking features 322), but the compliance members 384 may also allow the cradle rotor 304 to rotate relative to the cage 308 to, after a predetermined amount of relative rotation, lock one of the first locking features 320 and the second locking features 322 via compression. Therefore, during each cycle of the outside force applied to the cradle rotor 304, the compliance members 384 may enable the cradle rotor 304 to harvest the outside force in the direction of phasing and rotate relative to the stator 302 a predetermined amount, which is defined by the properties of the compliance members 384, and then stop due to the relative rotation between the cradle rotor 304 and the cage 308 provided by the compliance members 384. In this way, for example, the amount of phasing between the cradle rotor 304 and the stator 302 that occurs during each cycle of the outside force (e.g., cam torque pulse) may be known or predetermined for a given engine speed, position of the pin 354, and design (e.g., spring constant) of the compliance member 384.
In some non-limiting example, the functionality of the compliance member 384 may be provided by designing the cage arms 330 to rotationally flex, rather than providing a separate component (e.g., a spring) between the slot tube 348 and the cage 308.
General operation of the cam phasing system 300 including the compliance members 384 will be described with reference to
Turning to
Turning to
To initiate a phase change (i.e., a change in relative rotational orientation) between the cradle rotor 304 and the stator 302, a current may be applied to the solenoid 356 that displaces the pin 354 to one of the forward phasing region 381 or the backward phasing region 383. The following description references displacing the pin 354 to the backward phasing region 383, and it should be appreciated that the opposite process may occur for displacing the pin to the forward phasing region 381.
In the illustrated non-limiting example of
The pin 354 and the cage 308 may be prevented from moving due to the second locking features 322 being locked until the outside force reverses (e.g., from a direction that favors phasing to a direction that opposes phasing, or from a second direction to a first direction). As illustrated in
As the outside force applied to the cradle rotor 304 again begins to reverse (e.g., from a direction that opposes phasing to a direction that favors phasing, or from a first direction to a second direction), the cam phasing system 300 may pass through the unloaded state (i.e., the magnitude of the cam torque pulses may pass through zero). As illustrated in
Once the cam phasing system 300 transitions through the unloaded state and the outside force is again acting in a direction that favors phasing (e.g., a second direction, or counterclockwise from the perspective of
The locking of the second locking features 322 is enabled by the lash or relative rotation allowed by the compliance members 384 between the cradle rotor 304 and the cage 308. For example, the outside force in the second direction applied to the cradle rotor 304 may be applied to the pin 354 due to the rigid rotational coupling therebetween. This force biases the pin 354 against the second side 376 of the slot 362, which biases the cage 308, and thereby the second locking features 322 via engagement with the cage protrusions 328, in the second direction through the compliance members 384. As the pin 354 continues to be forced into the slot 362 by the cradle rotor 304, the compliance members 384 may flex rotationally to maintain the load on the pin 354 and the cage 308 from the cradle rotor 304 and allow the cradle rotor 304 to rotate relative to the cage 308. The compliance members 384 may provide enough lash or relative rotation between the cradle rotor 304 and the cage 308 to allow the cradle rotor 304 reach a rotational position where the second locking features 322 are locked via compression between the first mating surface 345 and the second mating surface 347. For example, the cradle rotor 304 may rotate faster (due to the coupling to the camshaft) than the biasing force from the compliance members 384 can accelerate the cage 308. This allows the cage 308 to initially displace the second locking features 322 relative to the cradle rotor 304 and then for the cradle rotor 304 to catch up and lock the second locking features 322, which results in the cradle rotor 304 rotating relative to the stator 302 and then locking once the second locking features 322 are compressed by the cradle rotor 304.
Once the second locking features 322 are locked via compression, further phasing between the cradle rotor 304 and the stator 302 may be prevented, but the cage 308 and the pin 354 may remain loaded in the second direction through the compliance members 384. Therefore, the compliance members 384 may control the amount of relative rotational motion between the cradle rotor 304 and the stator 302 that is harvested during each cycle of the outside force (e.g., cam torque cycle).
Turning to
In the mechanical cam phasing system 300 described herein, the solenoid 356 is arranged externally from the stator 302 and is configured to apply a linear displacement to the plunger 350. In some non-limiting examples, a pin may be placed in a slot or hole for each direction of motion as schematically illustrated in
When assembled, the solenoid 410 may be arranged internally within the stator 302. In some non-limiting examples, the solenoid 410 may be coupled to a front cover (not shown) of the mechanical cam phasing system 400 and may not rotate with the cradle rotor 404. The cradle rotor 404 may be rotationally coupled to a camshaft. The mechanical cam phasing system 400 may include a rotor insert 412. The rotor insert 412 may be rigidly attached to the cage 408.
In operation, when the solenoid is activated, rotational forces may be applied between the rotor insert 412 and the cradle rotor 404 in a tangential direction, which may lead to unlocking of the relative rotation between the cradle rotor 404 and the stator 402 in a desired direction. That is, rigidly coupling the rotor insert 412 and the cage 408 may pull the cradle rotor 404 and the cage 408 together in response to the rotational input force provided by the solenoid 410 in a desired direction.
The mechanical cam phasing systems 300, 400 described herein leverage the interference concept to selectively enable relative rotation between a camshaft and a crankshaft in a desired direction. In this way, for example, the mechanical cam phasing systems 300, 400 may provide significant benefits over conventional cam phasing systems. For example, the mechanical cam phasing systems 300, 400 may provide functionality at startup/shutdown of the internal combustion engine and during cold conditions, providing significant benefits when compared with conventional oil-based cam phasing systems. In addition, the simplified actuation of the mechanical cam phasing systems 300, 400 and the low input force requirements to facilitate the relative rotation between the camshaft and the crankshaft provide a low-cost solution when compared to conventional cam phasing systems (e.g., costs may be lower than conventional oil-based systems and significantly lower than conventional electronic cam phasing systems (e-phasing systems)). Further, the mechanical cam phasing systems 300, 400 may be capable of locking in any relative position between the camshaft and the crankshaft. That is, there are no restrictions to the magnitude of phasing allowed between the camshaft and the crankshaft, and full three-hundred and sixty degree phasing is achievable.
Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.
Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.
Various features and advantages of the invention are set forth in the following claims.
The present application is a continuation of U.S. patent application Ser. No. 16/704,992, filed on Dec. 5, 2019, which is based on and claims priority to U.S. Provisional Patent Application No. 62/776,924, filed on Dec. 7, 2018, and entitled “Mechanical Cam Phasing Systems and Methods.” Each of which is incorporated herein by reference in their entirety.
Number | Date | Country | |
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62776924 | Dec 2018 | US |
Number | Date | Country | |
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Parent | 16704992 | Dec 2019 | US |
Child | 17156109 | US |