Patent Application
20180119581
The present invention relates to a cam phaser, and, more particularly, to a sheet metal locking cover for a cam phaser.
Cam phasers are known devices which are used in engines to vary valve timing. Many cam phasers, such as vane-type cam phasers, include locking covers which are attached outside of the moving components of the phaser. The locking cover may act as a stationary component which helps to hold a rotor in a stator and facilitates locking of a locking pin.
Current manufacturing methods that are typically employed to form the locking cover 100 include molding using powdered metal and fine blanking. However these processes use a relatively large amount of raw material to produce the locking cover 100. In turn, cam phasers that utilize the known locking cover 100 are large, heavy, and have a high manufacturing cost, in part due to the locking cover construction. Attempting to address some of these issues by simply resizing the uniform thickness of the locking cover 100 is not a suitable solution as this would reduce its strength and render the locking cover 100 more susceptible to cracking or other types of deformation. Moreover, a uniformly thinner locking cover would not match the thickness of existing bushings 110.
The present disclosure is directed to overcoming one or more problems of the prior art.
In one aspect, the present disclosure is directed to a cam phaser. The cam phaser includes a stator, a rotor positioned in the stator, a cover plate positioned on a first side of the stator, a locking cover positioned on a second side of the stator, a locking pin assembly configured to selectively lock the rotor in a position relative to the stator, a plurality of aligned first openings which extend through the stator, the cover plate, and the locking cover, a plurality of fasteners respectively inserted in the plurality of aligned first openings, and a plurality of aligned central openings forming a throughbore. The locking cover includes a body formed from sheet metal having, a first axial side, a second axial side, a plurality of the first openings extending from the first axial side to the second axial aide, and a second opening extending from the first axial side to the second axial side. The body includes a web portion and a plurality of reinforcing portions which are thicker than the web portion.
In another aspect, the present disclosure is directed to a method of manufacturing a cam phaser. The cam phaser includes a stator, a rotor, a cover plate, a locking cover, a locking pin assembly, and a plurality of fastener. The method includes deep drawing a sheet metal blank to produce the locking cover which includes a body comprising web portion and a plurality of reinforcing portions which are thicker than the web portion, and stamping the blank to produce a plurality of first openings, a central opening, and a second opening. The method also includes assembling the cam phaser, including positioning the bushing in the second opening, positioning the locking cover adjacent to the stator, and inserting the plurality of fasteners through aligned openings in the cover plate, stator, and locking cover, the aligned openings including the plurality of first openings.
The foregoing summary and the following detailed description will be better understood when read in conjunction with the appended drawings, which illustrate a preferred embodiment of the invention. In the drawings:
The rotor 14 is positioned in the stator 12 and rotates therein (e.g., through hydraulic pressure) in order to vary a valve timing in a manner known in the art. For example a plurality of hydraulic chambers (not shown) may be formed between vanes of the stator 12 and rotor 14, with changing hydraulic pressures in the hydraulic chambers causing movement of the rotor 14 within the stator 12. The cover plate 16 is positioned on one side of the stator 12 and rotor 14, and the locking cover 18 is positioned on the opposite side of the stator 12 and the rotor 14. The stator 12, cover plate 16, and locking cover 18 preferably each include a plurality of first openings 24 for receiving a fastener 22 (e.g., bolt) when respectively aligned with each other. The rotor 14, cover plate 16, and locking cover 18 preferably each include a central opening 26. The locking cover 18 includes a second opening 28 for receiving a portion of the locking pin assembly 20, as will be described in further detail below.
The locking pin assembly 20 includes a pin 30, a spring 32, a movable locking part 36, and a bushing 38. The pin 30 is preferably attached to and movable with the rotor 14. The movable locking part 36 is positioned over an end of the pin 30 and is slidable on the pin 30 and biased into an extended position by the spring 32. Under certain conditions (e.g., hydraulic pressure above or below a threshold level, the movable locking part 36 is biased by the spring 32 into the bushing 38, which is cup shaped. Receipt of the movable locking part 36 in the bushing 38 locks the rotor 14 into a particular position relative to the stator 12, until the locking pin assembly 20 is unlocked by an increase in hydraulic pressure.
The locking cover 18 is formed of sheet metal and is thinner than prior art locking plates, such as locking cover 100 of
In the embodiment shown, the reinforcing portions are only provided on one side (e.g., the first axial side 42) of the locking cover 18. In this way, the second axial side 44 is flat over the entire side of the body 40 (i.e., planar) such that the locking cover 18 may be placed flat against the stator 12 and rotor 14 (see
As shown in
The exemplary disclosed locking cover 18 is preferably manufactured using a deep drawing and/or stamping process. In an exemplary disclosed process, a thin sheet metal blank is deep drawn to create the reinforcing portions (e.g., rim 46 and bosses 50, 52). A stamping step is also carried out to create the first openings 24, the central opening 26, and the second opening 28. This process produces the locking cover 18, which is substantially thinner than previous locking covers (e.g., locking cover 100), while maintaining a strength and rigidity necessary to withstand the forces associated with operation of the cam phaser 10.
In a further process, the locking cover 18 is assembled with the cam phaser 10. This process may include positioning the bushing 38 in the second opening 28, aligning the locking cover 18 with the rotor 14, and inserting the fasteners 22 through the first openings 24. During operation, the bushing 38 is positioned such that the movable locking part 36 is insertable into the bushing 38 to selectively lock the rotor 14 via the locking pin assembly 20.
The disclosed locking cover 18 thus provides a thinner component which uses less raw material (cost reduction), has less mass, takes up less space, and may be made through a more efficient process than previous locking covers.
Having thus described the presently preferred embodiments in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiments and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.
