Abstract:
A rotor for a camshaft phaser assembly for an internal combustion engine. The rotor includes a base portion from which protrudes a plurality of vanes spaced over the circumference of the base portion of the rotor. An increased diameter stepped portion of the base portion of the rotor is provided over at least one section between at least two of the protruding vanes. The increased diameter portion allows for insertion of at least one locking pin assembly within the base portion of the rotor, reducing the remaining rotor base portion diameter to at least reduce material weight and size of the camshaft phaser assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 of PCT/EP2010/068220 filed Nov. 25, 2010, which in turn claims the priority of U.S. 61/285,837 filed Dec. 11, 2009, the priority of both applications is hereby claimed and both applications are incorporated by reference herein. 
    
    
     BACKGROUND 
     The present invention relates to a camshaft adjuster or phaser for adjusting, and fixing, the phase position of a camshaft relative to a crankshaft of an internal combustion engine. 
     RELATED ART 
     Camshafts are used in internal combustion engines in order to actuate gas exchange valves. The camshaft in an internal combustion engine includes a plurality of cams that engage cam followers (i.e. bucket tappets, finger levers or rocker arms). When the camshaft rotates, the cams lift or depress the cam followers which in turn actuate gas exchange valves (intake, exhaust). The position and shape of the cams dictate the opening period and amplitude as well as the opening and closing time of the gas exchange valves. 
     Separate intake and exhaust camshaft assemblies are known in which each camshaft and its related cam lobes separately operate intake valves and exhaust valves, respectively. 
     Concentric camshaft assemblies are also known in which separate intake and exhaust camshafts are concentrically arranged by providing a hollow outer camshaft in which an inner camshaft is located, with the inner camshaft cam lobes being rotatable on the outer camshaft, and connected through slots in the hollow outer camshaft to the inner camshaft. This allows the use of separate camshafts for intake and exhaust valve actuation within generally the same space required for a single camshaft. 
     Camshaft phasers are used to advance or retard the opening or closing period, phasing the camshaft with respect to the crankshaft rotation. Camshaft phasers generally comprise a timing gear, which can be a chain, belt or gear wheel connected in fixed rotation to a crankshaft by a chain, belt or gear drive, respectively, acting as an input to the phaser. The phaser includes an output connection to the inner or outer camshaft in a concentric camshaft arrangement, or, alternatively, an output connection to an exhaust or intake camshaft. A phasing input is also provided in the form of a hydraulic, pneumatic or electric drive in order to phase or adjust the output rotation of the camshaft relative to the input rotation of the crankshaft. 
     Camshaft phasers are generally known in two forms, a piston-type phaser with an axially displaceable piston and a vane-type phaser with vanes that can be acted upon and pivoted in the circumferential direction. With either type, the camshaft phaser is fixedly mounted on the end of a camshaft. An example mounting may be performed as disclosed in U.S. Pat. No. 6,363,896, entitled “Camshaft Adjuster for Internal Combustion Engines”, by Wolfgang Speier, issued on Apr. 2, 2002, using a clamping screw forming the element of the camshaft phaser that effects centering relative to the camshaft. U.S. Pat. No. 6,363,896 is incorporated by reference herein in its entirety, as if set forth fully herein. 
     Camshaft phasers that operate according to the vane-cell principle for use on single camshafts are known in the art. U.S. Pat. No. 6,805,080, entitled “Device for changing the control times of gas exchange valves of internal combustion engines, particularly rotary piston adjustment device for rotation angle adjustment of a camshaft relative to a crankshaft”, by Eduard Golovatai-Schmidt et al., issued on Oct. 19, 2004, generally shows a construction of a vane-cell type camshaft phaser for use in an internal combustion engine. U.S. Pat. No. 6,805,080 is incorporated by, reference herein in its entirety, as if set forth fully herein. These single camshaft phasers are commonly used on dual overhead cam (DOHC) engines where intake and exhaust cam lobes are located on separate intake and exhaust camshafts. 
     It is also known to use camshaft phasers in connection with concentric camshaft assemblies for controlling the phase position of the inner camshaft, the outer camshaft, or both relative to each other. 
     In order to operate either of these types of phasers it can be useful to selectively supply an input medium. One method is to supply hydraulic fluid to ports in order to initiate movement. The vane-cell type phaser, in particular, employs a supply of hydraulic fluid, normally engine oil, to opposing chambers in the phaser in order to shift the vanes within the phases circumferentially and thus selectively phase cam timing. 
     Camshaft phasers are subject to oil loss from the phases through leakage. During normal engine operation engine oil pressure generated by the engine oil pump is sufficient to keep the cam phases full of oil and, therefore, functioning properly. However, when the engine is not operating, oil leakage from the cam phaser may leave the cam phaser chambers filled with air. This lack of controlling oil pressure and the presence of air in the chambers during engine start conditions, before the engine oil pump generates enough oil pressure and flow, may cause the phaser to oscillate excessively due to lack of oil. This oscillation may, in turn, cause noise or damage to the cam phases mechanism. In addition, it is desirable to have the cam phases locked in a particular position during engine start-up. 
     A solution known in the art is to introduce a locking pin that locks the earn phases in a specific position relative to the crankshaft when insufficient oil exists in the chambers. Typically, these locking pins are engaged by means of a spring and released using engine oil pressure. There are generally two locations in the cam phases for the locking pin; in the vane of the rotor of the cam phases or in the body of the rotor of the cam phases. 
     An example of a locking pin in the vane of the rotor is shown in U.S. Pat. No. 7,318,400, entitled “Locking Pin Mechanism for a Vane-Type Cam Phaser”, by Thomas L. Lipke et al., issued on Jan. 15, 2008. U.S. Pat. No. 7,318,400 generally shows a locking pin assembled into an expanded or over-sized rotor vane, as compared to the remaining rotor vanes. 
     Co-Pending Published U.S. Application No. 2006/0260578, entitled “Apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine” by Olaf Boese et al., published on Nov. 23, 2006 generally shows a locking pin assembled into the body or internal diameter of the rotor, U.S. Application No. 2006/0260578 is incorporated by reference herein in its entirety, as if set forth fully herein. 
     SUMMARY OF THE INVENTION 
     Certain terminology is used in the following description for convenience and descriptive purposes only, and is not intended to be limiting to the scope of the claims. The terms camshaft “phaser” and “adjuster” are used interchangeably. The terminology includes the words specifically noted, derivatives thereof and words of similar import. 
     As with many components in the modern internal combustion engine and automobile, it can be useful to reduce weight and size of components. In addition, it is useful to increase the surface area of rotor vanes in camshaft phasers. 
     To obtain the most effective and fuel saving operation possible for an internal combustion engine, it can be useful to change cam lobe (lift event) timing to crank shaft timing while the engine is operating. Camshaft phasers replace sprockets or pulleys on camshafts. The cam lobe angular position, or phase relationship, is controlled by the internal vane mechanism of the cam phaser. These vanes are moved circumferentially around the cam phaser by the use of oil supplied to either side of the vane, advancing or retarding the camshaft position. When the engine is shut-down, oil leaks out of the camshaft phaser system back into the oil reservoir of the engine. On engine start-up it is known in the art to provide a locking pin to prevent oscillation of the unfilled camshaft phaser. 
     An example aspect of the invention comprises a base portion of a rotor with a plurality of protruding vanes extending outwardly from the base portion to a housing. An increased step diameter of the rotor base portion relative to the remaining minor diameter of the rotor base portion is formed over at least one circumferential section between the protruding vanes. Within this increased diameter there is enough material through which a locking pin assembly may be inserted. The remaining sections of the base portion may be reduced in diameter, reducing material usage, weight and size of the entire camshaft phaser assembly. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above mentioned and other features and advantages of the embodiments described herein, and the manner of attaining them, will become apparent and be better understood by reference to the following description of at least one example embodiment in conjunction with the accompanying drawings. A brief description of those drawings now follows. 
         FIG. 1  is an exploded view of a camshaft phaser and locking pin, according to one embodiment of the invention. 
         FIG. 2 , is an enlarged front view of the camshaft phaser and locking pin of  FIG. 1 . 
         FIG. 3  is another enlarged isometric view of a camshaft phaser and locking pin of  FIG. 1 . 
         FIG. 4  is an exploded view of a camshaft phaser known in the art. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Identically labeled elements appearing in different ones of the figures refer to the same elements but may not be referenced in the description for all figures. The exemplification set out herein illustrates at least one embodiment, in at least one form, and such exemplification is not to be construed as limiting the scope of the claims in any manner. 
       FIG. 4  shows an exploded view of a camshaft phaser  100  known in the art. Camshaft phaser  100  comprises sprocket cover  101 , camshaft phaser assembly bolts  102 , locking pin  103 , locking pin spring  104 , locking pin cartridge  105 , rotor  106 , sealing lips  107 , sealing lip leaf spring  108 , housing  109 , front side cover  110 , sensor wheel  111  and drive screws  112 . In this example embodiment of camshaft phaser  100 , sprocket cover  101  acts as both the input drive from a chain (not shown) connected to the engine crankshaft (not shown) and the rear side cover for the camshaft phaser  100  assembly. Locking pin cartridge  105 , engaged with sprocket cover  101 , is pressed into rotor locking pin bore  114  in rotor  106  and is assembled with locking pin spring  104  and locking pin  103  in order to be inserted through locking pin bore  114  in rotor  106  and front cover locking pin interface  115  in front cover  110 . The locking contour may also be in the sprocket cover  101 . Locking pin cartridge  105  maintains only a slipping or loose interface with locking pin interface  113  on sprocket cover  101 , as during operation and rotation of rotor  106 , there is relative movement between sprocket cover  101  and locking pin cartridge  105 . Locking pin  103  is inserted through the rotor  106  in order to fix the position of the rotor  106  relative to the housing  109  particularly during engine startup, when the cam phaser  100  has no oil pressure supply for it to operate. 
     Leaf springs  108  are inserted into sealing lips  107 , which are then inserted into corresponding sealing lip grooves  116  in corresponding vanes  118  of rotor  106 . When rotor  106  is assembled into housing  109 , sealing lips  107  contact housing inner surface wall  117  of housing  109 , preventing pressurized fluid, such as engine oil, from moving between pressurized chambers formed by space between vanes  118  and corresponding housing protrusions  119 . Sprocket cover  101  and front side cover  110  are then placed in contact with either side of the assembled rotor  106  and housing  109 , and assembly bolts  102  are fixedly assembled through sprocket cover holes  120  in sprocket cover  101 , housing holes  121  in housing  109 , and side cover holes  122  in front side cover  110 . In turn, drive screws  112 , are inserted through sensor wheel  111  and into drive screw bores  128  in rotor  106  in order to fix the position of the sensor wheel  111  relative to rotor  106  at least during transportation of cam phaser  100 . Bolts (not shown) are inserted through sensor wheel holes  123  in sensor wheel  111 , side cover cam assembly holes  124  in front side cover  110 , rotor cam assembly holes  125  in rotor  106 , and seat in counter bores  126  in sprocket cover  101 , axially fixing sprocket cover  101  to a camshaft (not shown) when bolts (not shown) are fixedly assembled into a camshaft (not shown). A further notable feature in  FIG. 4  are rotor oil ports  127 , through which pressurized fluid, such as engine oil, pressurizes a pressure chamber of the camshaft phaser  100 , exerting force on one side of vanes  118  causing rotation of the rotor  106  and phasing of an associated camshaft (not shown). 
       FIG. 1  shows an exploded view of a camshaft phaser  1  constructed according to an embodiment of the invention. Camshaft phaser  1  comprises housing-sprocket  29 , camshaft phaser assembly bolts  3 , locking pin  4 , locking pin spring  5 , locking pin cartridge  6 , rotor  7 , sealing lips  8 , sealing lip leaf spring  9 , front side cover  11 , and secondary gear drive cover  30 . In this embodiment of camshaft phaser  1 , housing-sprocket  29  acts as both the input drive from a chain (not shown) connected to the engine crankshaft (not shown) and the stator or housing for the camshaft phaser  1  assembly. In other embodiments, the sprocket and stator/housing may be separate components, as shown in the prior art of  FIG. 4 . 
     Locking pin cartridge  6  is assembled with locking pin spring  5  and locking pin  4  and then inserted through locking pin bore  15  in rotor  7  and gear drive locking pin interface  31  in secondary gear drive cover  30 . The locking pin components may also be reversed in configuration, with the locking pin cartridge  6  and remaining components interfacing with a locking pin interface in front side cover  11  instead of or in addition to locking pin interface  31  in secondary gear drive cover  30 . In the embodiment shown, locking pin cartridge  6  maintains only a slipping or loose interface with front side cover  11 , as during operation and rotation of rotor  7 , there is relative movement between front side cover  11  and locking pin cartridge  6 . Locking pin  4  is inserted through the rotor  7  in order to fix the position of the rotor  7  relative to the housing-sprocket  29  particularly during engine startup, when the cam phaser  1  has no oil pressure supply for it to operate. 
     Rotor  7  comprises a base portion  38  and protruding vanes  19  extending outwardly from base portion  38 . Locking pin bore  15  is located within an increased step diameter  32  of rotor  7  between vanes  19 . The remaining circumferential segments of rotor  7  have a relatively generally reduced diameter, as can be seen in  FIG. 2 . When there is no oil pressure, such as before or during engine start up, locking pin spring  5  urges locking pin  4  into gear drive locking pin interface  31 . Locking pin  4  becomes disengaged from gear drive locking pin interface  31  with the introduction of minimal oil pressure to camshaft phaser  1  after engine start-up, particularly when engine oil is supplied to gear drive locking pin interface  31  and also can become disengaged with housing sprocket  29  in this manner, as well. When locking pin  4  is disengaged from gear drive locking pin interface  31  and housing-sprocket  29 , relative movement between rotor  7  and housing-sprocket  29  is allowed, enabling earn phasing operation of the camshaft phaser. 
       FIG. 2  shows an enlarged front view of camshaft phaser  1  of  FIG. 1  with front side cover  11  and assembly bolts  3  removed. Increased step diameter  32  of base portion  38  of rotor  7  is shown, interacting with reduced diameter housing protrusion  33  in housing-sprocket  29 . Increased step diameter  32  provides sufficient material through which locking pin assembly  35 , consisting of locking pin  4 , locking pin spring  5  and locking pin cartridge  6 , may be inserted. Reduced volume pressure cavity  36  is formed in a volume created by rotor increased step diameter  32 , reduced step diameter housing protrusion  33  and vane  19 . Pressure cavities  34  are formed in a volume created by rotor  7 , vanes  19  and housing protrusions  20 . Oil ports  37  in rotor  7  allow for ingress and egress of engine oil from pressure cavities  36 . As is shown, pressure cavities  34  may be larger than a similar camshaft phaser in which a diameter of rotor  7  is uniform throughout its circumference. This reduction in diameter of rotor  7  in the portions of the circumference other than that of increased step diameter  32  also allows for increased surface area of vanes  19  at those other areas, which, in turn allows force to be exerted over that increased surface area of vanes  19  by a constant engine oil pressure during operation of camshaft phaser  1 . Also shown are sealing lips  8  and leaf springs  9 . 
       FIG. 3  shows an isometric assembly view of the camshaft phaser  1  of  FIG. 1  with front side cover  11  and assembly bolts  3  removed. More clearly visible are oil ports  37  in rotor  7  in their operating positions supplying pressure cavities  34  and reduced volume pressure cavity  36 . Also shown are sealing lips  8  and leaf springs  9 , housing protrusions  20 , reduced diameter housing protrusion  33 , rotor increase step diameter  32 , secondary gear drive cover  30 , housing-sprocket  29  and locking pin cartridge  6 . 
     In the foregoing description, embodiments are described. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense. It will, however, be evident that various modifications and changes may be made thereto, without departing from the broader spirit and scope of the present invention. 
     In addition, it should be understood that the figures illustrated in the attachments, which highlight the functionality and advantages of the example embodiments, are presented for example purposes only. The architecture or construction of embodiments described herein is sufficiently flexible and configurable, such that it may be utilized (and navigated) in ways other than that shown in the accompanying figures. 
     Although embodiments have been described herein, many additional modifications and variations would be apparent to those skilled in the art. It is therefore to be understood that this invention may be practiced otherwise than as specifically described. Thus, the present embodiments should be considered in all respects as illustrative and not restrictive. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Camshaft Phaser 
           3  Assembly Bolts 
           4  Locking Pin 
           5  Locking Pin Spring 
           6  Locking Pin Cartridge 
           7  Rotor 
           8  Sealing Lips 
           9  Leaf Springs 
           11  Front Side Cover 
           15  Locking Pin Bore 
           17  Sealing Lip Groove 
           18  Housing Inner Surface Wall 
           19  Vane 
           20  Housing Protrusions 
           22  Housing Hole 
           29  Housing-sprocket 
           30  Secondary gear drive cover 
           31  Gear drive locking pin interface 
           32  Increased step diameter 
           33  Reduced diameter housing protrusion 
           34  Pressure cavity 
           35  Locking pin assembly 
           36  Reduced volume pressure cavity 
           37  Oil ports 
           38  Base portion 
           100  Prior art camshaft phaser 
           101  Sprocket cover 
           102  Assembly Bolts 
           103  Locking Pin 
           104  Locking Pin Spring 
           105  Locking Pin Cartridge 
           106  Rotor 
           107  Sealing Lips 
           108  Leaf Springs 
           109  Housing 
           110  Front Side Cover 
           111  Sensor Wheel 
           112  Drive Screws 
           113  Sprocket Cover Locking Pin Interface 
           114  Locking Pin Bore 
           115  Front Cover Locking Pin Interface 
           116  Sealing Lip Groove 
           117  Housing Inner Surface Wall 
           118  Vane 
           119  Housing Protrusions 
           120  Sprocket Cover Hole 
           121  Housing Hole 
           122  Side Cover Hole 
           123  Sensor Wheel Hole 
           124  Site Cover Cam Assembly Hole 
           125  Rotor Cam Assembly Hole 
           126  Counter Bores 
           127  Rotor Oil Ports 
           128  Drive Screw Bores