The present disclosure relates generally to camshaft phasers and more specifically to locking pins for camshaft phasers.
BACKGROUND
Camshaft phasers can include a rotor movable with respect to a stator by fluid and a locking pin for fixing the rotor with respect to the stator.
SUMMARY OF THE INVENTION
A camshaft phaser includes a stator, a rotor rotatable with respect to the stator, a locking cover non-rotatably fixed to the stator and a locking assembly including a locking part configured for engaging with the locking cover to selectively lock the rotor with respect to the stator. The locking part is configured for being movable via hydraulic fluid in a hole in the rotor. The locking part or a surface of the hole including a groove configured for receiving contaminant particles in the hydraulic fluid.
In embodiments of the camshaft phaser, the groove may be in an outer circumferential surface of the locking part. The groove may be an annular groove extending continuously in the outer circumferential surface. The locking assembly may include a spring axially biasing the locking part. The spring may be configured for forcing the locking part into the locking cover in a locking orientation of the locking assembly and the camshaft phaser may be configured such that the hydraulic fluid compresses the spring to hold the spring axially away from the locking cover in an unlocking orientation of the locking assembly. The locking assembly may include a base and the spring may be sandwiched axially between the base and the locking part. The locking part may include an end section configured for abutting the locking cover and a cylindrical section delimiting a blind hole receiving a portion of the spring. The groove may be formed in the cylindrical section. The locking assembly may be configured such that an outer circumferential surface of locking part is slidable axially along the surface of the hole in the rotor. An axial contact surface of the locking part may be configured for contacting an axial contact surface of the locking cover. The groove may be spaced from the axial contact surface of the locking part such that the groove is radially aligned with the surface of the hole in the rotor through an entire axial movement path of the locking part.
A method of constructing a camshaft phaser is also provided. The method includes providing a stator and a rotor rotatable inside the stator; non-rotatably fixing a locking cover to the stator; and providing a locking assembly including a locking part configured for engaging with the locking cover to selectively lock the rotor with respect to the stator. The locking part is configured for being movable via hydraulic fluid in a hole in the rotor. The locking part or a surface of the hole including a groove configured for receiving contaminant particles in the hydraulic fluid.
In embodiments of the method, the providing of the locking assembly may include inserting the locking assembly into the hole in the rotor. The providing of the locking assembly may include fixing a bushing of the locking cover over the hole in the rotor after the inserting of the locking assembly into a hole in the rotor. The locking assembly may be configured for axially forcing the locking part against the bushing in a locking orientation of the locking assembly. The locking assembly is inserted in the hole such that an outer circumferential surface of locking part is slidable axially along the surface of the hole in the rotor. The locking assembly may be inserted in the hole such that an axial contact surface of the locking part is configured for contacting an axial contact surface of the locking cover and the groove is spaced from the axial contact surface of the locking part such that the groove is radially aligned with the surface of the hole in the rotor through an entire axial movement path of the locking part. The method may further include forming the groove in an outer circumferential surface of the locking part. The locking part may include an end section configured for abutting the locking cover and a cylindrical section delimiting a blind hole receiving a portion of the spring. The forming of the groove in the outer circumferential surface of the locking part may include forming the groove in the cylindrical section. The providing of the locking assembly may include arranging a spring of the locking assembly axially between a base of the locking assembly and the locking part such that the spring axially biases the locking part away from the base.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is described below by reference to the following drawings, in which:
FIGS. 1a and 1b show perspective cross-sectional views of a camshaft phaser for an internal combustion engine in accordance with an embodiment of the present invention;
FIGS. 2 and 3 show enlarged cross-sectional views of a portion of the camshaft phaser including a locking assembly;
FIGS. 4a, 4b and 4c show different perspective views of a locking part of the locking assembly;
FIGS. 5a and 5b show different perspective views of a rotor of the camshaft phaser; and
FIG. 6 shows an enlarged cross-sectional view of a portion of a camshaft phaser in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION
The present disclosure provides a camshaft phaser including a locking pin or rotor configured to prevent contaminants from getting stuck inside the locking assembly.
FIGS. 1a and 1b show perspective cross-sectional views of a camshaft phaser 10 for an internal combustion engine in accordance with an embodiment of the present invention. Camshaft phaser 10 includes a stator assembly 12 configured for connecting to a crankshaft of the engine and a rotor 14 configured for connecting to a camshaft. Rotor 14 is rotatable with respect to stator assembly 12 about a center axis CA of camshaft phaser 10. Unless otherwise specified herein, the terms radial, axial and circumferential and derivatives thereof are used with respect to center axis CA. Stator assembly 12 includes a stator 16 having a sprocket 17, which includes plurality of circumferentially spaced teeth 17a configured for engaging with a timing chain or belt driven by the crankshaft of the engine. Stator assembly 12 also includes a locking cover 18 on a first axial side of stator 16 and a cover plate 20 on a second axial side of stator 16. Stator 16, locking cover 18 and cover plate 20 define an annular volume in which rotor 14 is received. More specifically, stator 16 includes an annular section 22 having an inner circumferential surface 24 defining an outer circumference of the annular volume, and locking cover 18 and cover plate 20 each include a respective radially extending inner surface 18a, 20a forming axial boundaries of the annular volume.
In a known manner, annular section 22 may include a plurality of circumferentially spaced lobes that protrude radially inward further than outermost sections of inner circumferential surface 24. Rotor 14 includes a plurality of circumferentially spaced vanes 26 protruding radially outward from a center section 28 of rotor 14. FIGS. 5a and 5b show perspective views of rotor 14, illustrating vanes 26. Each of vanes 26 is received in a respective hydraulic working chamber formed circumferentially between two of the lobes, with each hydraulic working chamber being divided into two working subchambers by the respective vane 26. In order to seal the two working subchambers from each other, each vane 26 is provided with a seal 29 held a groove in the vane 26 that is forced radially outward against inner circumferential surface 24 by a spring 30. Rotor 14 rotates inside of stator 16 through hydraulic pressure in order to vary a valve timing in a known manner due to pressure differences between the two working subchambers.
Cover plate 20 is positioned on a first axial side of rotor 14, and the locking cover 18 is positioned on a second axial side of rotor 14. Stator 16, locking cover 18 and cover plate 20 are fixed together by a plurality of fasteners 31 passing through annular section 22, locking cover 18 and cover plate 20, with the fasteners 31 passing through the lobes of annular section 22.
Camshaft phaser 10 further includes a locking assembly 32 that includes a base 34, a coil spring 36 and an axially movable locking part 38. FIGS. 2 and 3 show enlarged views the section of phaser 10 including locking assembly 32. Base 34 may be attached to and rotatably movable with rotor 14 via mounting in a cylindrical hole 40 extending axially through rotor 14. A first axial end 34a of base 34 axially abuts inner radially extending surface 20a of cover plate 20. Locking part 38 is positioned over a second axial end 34b of base 34 and is axially slidable on base 34. A first axial end 36a of spring 36 axially abuts base 34 and a second axial end 36b of spring 36 abuts locking part 38.
Locking base 34 includes a support section 42 configured for fixing base 34 axially in place in rotor 14 and a pin-shaped axial protrusion 44 extending axially from support section 42. Support section 42 is radially wider than protrusion 44 and includes a radially outwardly extending collar 42a for engaging with an edge 46a defined by a groove 46b formed in rotor 14 to hold base 34 axially in place in rotor 14. Protrusion 44 has a tapered outer circumferential surface 44a that forms a form fit connection with an inner circumference of first axial end 36a of spring 36.
Locking part 38 is cup shaped and includes a disk shaped end section 38a and a cylindrical section 38b extending axially from end section 38a away from locking cover 18. Cylindrical section 38b surrounds a portion of spring 36 and defines a blind hole 38c receiving the portion of spring 36. Blind hole 38c also receives a portion of axial protrusion 44. Second axial end 36b of spring 36 axially abuts an inner radially extending surface 38g of end section 38a. More specifically, locking cover 18 includes a hole 48 extending axially therethrough and a bushing 50 received in hole 48. Bushing 50 is cup shaped and includes a disk shaped end section 50a and a cylindrical section 50b extending axially from end section 50a toward rotor 14. Cylindrical section 50b is configured for surrounding end section 38a of locking part 38 and defines a blind hole 50c receiving end section 38a. A rim 50g of cylindrical section 50b abuts a radially extending surface 14a of rotor 14.
In an extended orientation of locking assembly 32—i.e., a locking orientation of locking assembly 32, which is shown in FIG. 2, end section 38a is received inside of locking cover 18 due to spring 36 biasing locking part 38 away from base 34 such that locking part 38 prevents rotor 14 from being rotated with respect to stator 16. More specifically, end section 38a is received in the blind hole 50c of bushing 50 in the extended orientation such that locking part 38 circumferentially contacts inner circumferential surface 50d of cylindrical section 50b to prevent rotor 14 from being rotated with respect to stator 16. In a retracted orientation of locking assembly 32—i.e., an unlocking orientation of locking assembly 32, locking part 38 is forced out of locking cover 18 by hydraulic fluid such that locking part 38 is sufficiently inside of rotor 14 and locking part 38 is not arranged to prevent rotor 14 from being rotated with respect to stator 16. More specifically, end section 38a is sufficiently displaced from blind hole 50c and sufficiently received in the rotor 14 in the retracted orientation such that rotor 14 is rotatable with respect to stator 16.
To switch locking assembly 32 from the extended orientation to the retracted orientation, fluid is forced through a channel 52 (FIGS. 5a, 5b) in rotor 14 into a fluid chamber 54 defined between bushing 50 and locking part 38. As shown in FIGS. 5a, 5b, channel 52 is recessed into radially extending surface 14a of rotor 14 and extends radially inward from an outer circumferential surface 28a of center section 28 of rotor 14 into hole 40 of rotor 14. As the hydraulic pressure in chamber 54 axially overcomes the axial force of spring 36, the hydraulic pressure forces locking part 38 axially away from bushing 50 and further into hole 40 in rotor 14, axially expanding chamber 54. After locking part 38 is pushed sufficiently into rotor 14, pressure differences in the working subchambers defined between rotor 14 and stator 16 can be used to rotate rotor 14 with respect to stator 16 in a known manner. Locking part 38 may be pushed sufficiently into rotor 14 if end section 38a is entirely inside of hole 40 or if enough of end section 38a is in hole 40 such that rotation of rotor 14 causes locking cover 18, via bushing 50, to force end section 38a entirely inside of hole 40. More specifically, enough of end section 38a may be hole 40 if hydraulic pressure in chamber 54 forces locking part 38 into hole such that contact between an angled edge surface 38d of end section 38a of locking part 38 and an angled edge surface 50e of cylindrical section 50b of bushing 50 during rotation of rotor 14 forces end section 38a entirely inside of hole 40.
While locking part 38 is moved axially within hole 40, an outer circumferential surface 38e of locking part 38 slides axially along an inner circumferential surface 40a of hole 40. During such sliding, particles that may be present in the hydraulic fluid, for example metal particles via contamination from the engine oil, provided to chamber 54 may be forced between outer circumferential surface 38e of locking part 38 and inner circumferential surface 40a of hole 40. In order to prevent the particles from getting stuck between outer circumferential surface 38e and inner circumferential surface 40a in a manner that causes locking part 38 to jam, thus preventing axial movement of locking part 38, an annular groove 58 is formed in outer circumferential surface 38e. Annular groove 58 is configured to receive and retain particles that enter between outer circumferential surface 38e and inner circumferential 40a to prevent locking part 38 from getting axially stuck in place.
FIGS. 2 and 3 show locking assembly 32 with spring 36 forcing locking part 38 against bushing 50 such that an axial contact surface 38f of locking part 38 contacts an axial contact surface 50f of bushing 50 and annular groove 58 is radially aligned with inner circumferential surface 40a. Annular groove 58 is spaced from axial contact surface 38f such that annular groove 58 is radially aligned with inner circumferential surface 40a through the entire axial movement path of locking part 38—i.e., annular groove 58 is radially aligned with inner circumferential surface 40a in a maximum extent of the locking orientation and a maximum extent of the unlocking orientation.
FIGS. 4a, 4b and 4c show different perspective views of locking part 38. As shown in FIG. 4a, locking part 38 includes a curved edge 60 connecting outer circumferential surface 38e with a radially extending locking cover facing surface 62 of locking part 38. Surface 62 includes axial contact surface 38f in the form of an annular rim section for contacting bushing 50 and surface 62 includes a central section 62a inside of axial contact surface 38 that is axially recessed away from axial contact surface 38f At and end of locking part 38 axially opposite of surface 62, locking part 38 includes an annular rim surface 64 forming a free edge of cylindrical section 38b and delimiting an opening of blind hole 38c. In the embodiment shown in FIGS. 4a to 4c, annular groove 58 is a continuous groove extending circumferentially along an entirety of outer circumferential surface 38e and is defined by a curved surface 66 dividing outer circumferential surface 38e into a first section 68a and a second section 68b. Groove 58 can be formed in locking part 38 using a cold forming rolling process after the locking part is stamped, or groove 58 can be formed by machining.
In an alternative embodiment shown in FIG. 6, instead of groove 58 being formed in locking part 38, an annular groove 70 configured for receiving contaminant particles in the hydraulic fluid is formed in inner circumferential surface 40a of hole 40 of rotor 14. Similar to annular groove 58, annular groove 70 is a continuous groove extending circumferentially along an entirety of inner circumferential surface 40a and is defined by a curved surface 72. Annular groove 70 is configured to receive and retain particles that enter between surfaces outer circumferential surface 38e and inner circumferential 40a to prevent locking part 38 from getting axially stuck in place.
In the preceding specification, the invention has been described with reference to specific exemplary embodiments and examples thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.
LIST OF REFERENCE NUMERALS
- CA center axis
10 camshaft adjuster
12 stator assembly
14 rotor
14
a radially extending surface
16 stator
17 sprocket
17
a teeth
18 locking cover
18
a radially extending inner surface
20 cover plate
20
a radially extending inner surface
22 annular section
24 inner circumferential surface
26 vane
28 center section
28
a outer circumferential surface
29 seal
30 spring
31 fasteners
32 locking assembly
34 base
34
a first axial end
34
b second axial end
36 coil spring
36
a first axial end
36
b second axial end
38 locking part
38
a end section
38
b base section
38
c blind hole
38
d angled surface
38
e outer circumferential surface
38
f axial contact surface
38
g inner radially extending surface
40 hole
40
a inner circumferential surface
42 support section
42
a radially outwardly extending collar
44 axial protrusion
46
a edge
46
b groove
48 hole
50 bushing
50
a end section
50
b cylindrical section
50
c blind hole
50
d inner circumferential surface
50
e angled edge surface
50
f axial contact surface
50
g rim
52 channel
54 hydraulic chamber
58 annular groove
60 curved edge
62 locking cover facing surface
62
a central section
64 annular rim surface
66 curved surface
68
a first outer circumferential surface section
68
b second outer circumferential surface section
Patent Application
20200325801
