Patent Application
20120227692
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.
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.
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.
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.
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.
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
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
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.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/068220 | 11/25/2010 | WO | 00 | 5/17/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 61285837 | Dec 2009 | US |
