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AssigneeToyota Jidosha Kabushiki Kaisha
InventorsMamoru Yoshioka, Haruyuki Obata, Ken Tanoue, Yoshihiro Iwashita, Toshimi Kashiwagura, Makoto Suzuki, Hiroki Ichinose, Hironori Okamizu
Estimating the term…
The variable valve timing control device according to the present invention controls the valve timing of the intake valves of the engine based on the optimum valve timing at the full load operation of the engine. Namely, the variable valve timing control device of the present invention determines the valve timing in accordance with the combination of the present engine load and the present engine speed in such a manner that the deviation of the valve timing from the optimum valve timing when the engine is operated in full load at the present speed does not exceed a predetermined maximum allowable value. Since the valve timing of the engine is always set within a range determined by the maximum allowable deviation from the optimum valve timing for the full load operation, when the engine is accelerated to the full load condition the amount of the change, i.e., the amount of the operation of the variable valve timing control device is kept always within the range determined by the maximum allowable deviation. Therefore, the time required for changing the valve timing to the optimum valve timing for the full load operation is always short regardless of the present operating condition of the engine. Consequently, the response of the valve timing control can be improved without increasing the operating speed of the variable valve timing control device.
A variable valve timing control device, for an engine, for controlling the valve timing of the engine, in accordance with an operating condition thereof, comprising:
A variable valve timing control device for an engine for controlling the valve timing of the engine in accordance with an operating condition thereof comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Using helically teethed sleeve or gear moving axially between crankshaft and camshaft: the helically teethed sleeve being located in the camshaft…
Variable control of intake and exhaust valves: changing the valve timing only
Variable control of the intake valves only: changing the valve timing only
During engine operation: controlling the valve overlap
Term ended 13 Mar 2015 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a variable valve timing control device for an internal combustion engine which controls the valve timing of the engine in accordance with the operating condition thereof.
2. Description of the Related Art
The present invention will be better understood from the description, as set forth hereinafter, with reference to the accompanying drawings in which:
FIG. 1 is a sectional view illustrating the construction for an embodiment of the variable valve timing control device according to the present invention;
FIG. 2 is a timing chart schematically illustrating the general setting of the valve timings of the intake and the exhaust valves;
FIG. 1 shows an embodiment of the variable valve timing control device, according to the present invention, applied to inlet valves of a four-stroke internal combustion engine. In this embodiment, a double overhead camshaft (DOHC) engine having an intake camshaft and an exhaust camshaft for driving intake valves and exhaust valves of the engine, respectively, is used, and the variable valve timing control device is applied only to the intake camshaft. Namely, in this embodiment, the valve timing of the exhaust valves are fixed while the valve timing of the intake valves are changed in accordance with the operating conditions of the engine. However, the present invention is not limited to this embodiment. For example, the present invention can be also applied to the variable valve timing control device controlling the exhaust valves only, or both the intake and the exhaust valves.
In FIG. 1, numeral 1 designates an intake camshaft of a DOHC engine which drives intake valves of the respective cylinders. Numeral 10 indicates a valve timing adjusting mechanism attached to an end of the intake camshaft 1. The valve timing adjusting mechanism 10 comprises a timing pulley 12 having a cylindrical sleeve 13, and a housing 14 which covers the end portion of the intake camshaft 1. The timing pulley 12 is attached to the outer surface of the intake camshaft 1 by the sleeve 13 in such a manner that the pulley 12 can freely rotate around the camshaft 1. The housing 14 is secured to the timing pulley 12 by bolts 15 and rotate integrally with the pulley 12.
In the housing 14, a piston member 17 is disposed. The piston member 17 consists of an annular piston 19 and a cylindrical sleeve 21 extending from the annular piston 19 in coaxial manner. The annular piston 19 can slide axially on the camshaft 1 while maintaining close contact between its inner periphery and the outer surface of the camshaft 1, and between its outer periphery and the inner surface of the housing 14. On the outer surface of the cylindrical sleeve 21 of the piston member 17, an outer helical gear 21a having a predetermined tooth helix angle is formed. Similarly, an inner helical gear 21b having a predetermined tooth helix angle is formed on the inner surface of the cylindrical sleeve 21. The teeth of the outer helical gear 21a engage the teeth of an inner helical gear 22a formed on the inner surface of the housing 14. The teeth of the inner helical gear 21b engage the teeth of a ring-like outer helical gear 22b fixed to the end of the intake camshaft 1 by a bolt 1a and a pin 1b.