Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1991-11-07
1992-10-06
Cross, E. Rollins
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9031, 123502, F01L 134
Patent
active
051522616
ABSTRACT:
A driveshaft in the form of a crankshaft (12) or a camshaft (212) drives a camshaft (16, 216) by means of a chain (20, 220) which is trained around a sprocket (14, 214) on the driveshaft and another sprocket (18, 218) on the driven camshaft. The driven camshaft is selectively advanced or retarded in its position by lengthening or shortening one portion (20a, 220a) of the chain and simultaneously lengthening or shortening another portion (20b, 220b) thereof by extending one hydraulic tensioning device (22, 122, 222, 322) and simultaneously retracting another hydraulic tensioning device (24, 124, 224, 324). A spool valve member (50) is controllably positioned within a valve body (48), in response to instructions from an engine control unit (58) which acts through a pulse width modulated solenoid (56) to increase or decrease a load acting on one end of the spool, to permit or prevent hydraulic fluid from flowing from one tensioner to another as a result of a pressure differential between the tensioners. The pressure differential exists as a result of torque reversals in the driven camshaft during its normal rotation, the torque reversals having the effect of changing the levels of tension within the portions of the chain that are engaged by the tensioners.
REFERENCES:
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patent: 5002023 (1991-03-01), Butterfield et al.
"System for Automatic Variation of Phase Between Two Camshafts, Inserted o a `Cassette Module`, With Sachs-Huret Chain"-presented in or about 1983.
Butterfield Roger P.
Smith Franklin R.
Borg-Warner Automotive Transmission and Engine Components Corp.
Cross E. Rollins
Lo Weilun
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