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US 2003/0196623 A1Published application
Vct lock pin having a tortuous path providing a hydraulic delay
AssigneeBorgWarner Inc.
InventorJeff Lewis
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AssigneeBorgWarner Inc.
InventorJeff Lewis
Estimating the term…
A variable cam timing phaser having a tortuous path from the supply of pressurized oil to the tapered recess into which the locking pin fits, that introduces a delay between when the engine starts and when the locking pin moves to an unlocked position. The tortuous path restricts fluid flow, preventing the locking pin from unlocking during engine start-up with the initial oil pressurization, prior to the variable cam timing phaser having sufficient oil to operate. The delay ensures that the chambers of the variable cam timing phaser have time to fill with operating fluid before the phaser is unlocked.
A variable camshaft timing phaser for an internal combustion engine having at least one camshaft comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
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Changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear: using hydraulic chambers with variable volume to…
Locking means between driving and driven members: locking position intermediate between most retarded and most advanced positions
Locking means between driving and driven members: lock movement perpendicular to camshaft axis
Camshaft drives characterised by their transmission means: the camshaft being driven by chains
Term end not estimated
1. Field of the Invention
The invention is related to a hydraulic control system for controlling the operation of a variable camshaft timing (VCT) system. More specifically, the present invention relates to a control system, which utilizes a tortuous or restricted path to delay the release of the locking pin.
2. Description of Related Art
FIG. 1 shows a front view of a VCT phaser incorporating the invention.
FIGS. 2a & 2b shows engaged and disengaged positions of the present invention respectively, in detail from within box 2 in FIG. 1.
Referring to FIG. 1, a vane-type VCT phaser comprises a housing (1), the outside of which has sprocket teeth (8) which mesh with and are driven by timing chain (9). Inside the housing (1) are fluid chambers (6) and (7). Coaxially within the housing (1), free to rotate relative to the housing, is a rotor (2) with vanes (5) which fit between the chambers (6) and (7), and a central control valve (4) which routes pressurized oil via passages (12) and (13) to chambers (6) and (7), respectively. Pressurized oil introduced by valve (4) into passages (12) will push vanes (5) counterclockwise relative to the housing (1), forcing oil out of chambers (6) into passages (13) and into valve (4).
It will be recognized by one skilled in the art that this description is common to vane phasers in general, and the specific arrangement of vanes, chambers, passages and valves shown in FIG. 1 may be varied within the teachings of the invention. For example, the number of vanes and their location can be changed—some phasers have only a single vane, others as many as a dozen, and the vanes might be located on the housing and reciprocate within chambers on the rotor. The housing might be driven by a chain or belt or gears, and the outside of the housing might be sprocket teeth as shown, or a pulley for a belt, or gears.
Referring to FIG. 1 and the detail of FIG. 2a, in the phaser of the invention, a locking pin (10) slides in a bore (17) in the housing (1), and is pressed by a spring (21) into a recess (19) in the rotor (2) to lock the rotor (2) and housing (1) into a fixed rotational position. A vent (11) allows any oil, which might leak past the piston (10) to be discharged. A bushing (16) may be provided in the bore, surrounding at least the inner end (20) of the locking pin, to provide a better seal.