Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2003-03-27
2004-05-25
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090150, C123S090120, C464S001000, C464S002000, C464S160000, C092S120000, C092S00500L
Reexamination Certificate
active
06739298
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2002-88300 filed on Mar. 27, 2002, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a valve timing adjusting apparatus that adjusts valve opening and closing timing (a valve timing) of at least one of an intake valve and an exhaust valve of an internal combustion engine (engine) and a method of controlling the same.
2. Description of Related Art
There is known a valve timing adjusting apparatus in which valve timing of at least one of an intake valve and an exhaust valve is adjusted by hydraulically controlling angular phase of a driven side rotating member rotatable together with a camshaft relative to a drive side rotating member receiving drive force from a crankshaft of an engine and rotatable together with the crankshaft, that is, controlling angular phase of the camshaft relative to the crankshaft to a given value.
According to a conventional vane type valve timing adjusting apparatus, a vane as the driven side rotating member is accommodated in the drive side rotating member in such a manner that angular phase of the vane relative to the drive side rotating member is variable and defined by controlling hydraulic pressure applied to the vane. Further, according to another conventional valve timing adjusting apparatus, a drive force transmitting member disposed between the drive side rotating member and the driven side rotating member is provided with a helical spline engagement mechanism and angular phase of the driven side rotating member relative to the drive side rotating member is varied by hydraulically moving reciprocatingly the drive force transmitting member.
In the valve timing adjusting apparatus mentioned above, it is preferable for a purpose of preventing engine cranking failure when the engine is cranked that the valve timing of at least one of the intake valve and the exhaust valve is kept at a middle between the most retard timing and the most advanced timing that is the most adequate timing for securing efficient engine cranking.
For example, in the valve timing adjusting apparatus in which a piston is provided in the driven side rotating member and a fitting hole, in which the piston can be fitted, is provided in the drive side rotating member, the angular phase of the driven side rotating member relative to the drive side rotating member is locked to the middle position between the most retard angular position and the most advanced angular position by inserting the piston into the fitting hole when the engine stops. Operation of fitting the piston in the fitting hole or operation of pulling the piston out of the fitting hole is controlled by force balance between biasing force of a spring urging the piston toward the fitting hole and hydraulic pressure acting on the piston in a direction in which the piston is pulled out of the fitting hole.
Further, in a certain engine condition, for example, in a case of rapidly reducing vehicle speed during a period when the vehicle is running at high and constant speed, it is preferable for preventing abnormal engine operation that the valve timing is held within a limited range between the most retard timing and the most advanced timing by controlling the angular phase of the driven side rotating member relative to the driven side rotating member to keep within an angular range corresponding to the limited range.
For example, in the valve timing adjusting apparatus in which the drive side rotating member is provided with an arc shaped restriction hole extending in a direction in which the driven side rotating member rotates relatively to the drive side rotating member and the driven side rotating member is provided with a piston that can be inserted into the restriction hole, the angular phase of the driven side rotating member relative to the drive side rotating member is controlled within an angular range defined with opposite ends of the arc shaped restriction hole by inserting the piston into the restriction hole.
However, rotating speed of the driven side rotating member relative to the drive side rotating member, speed of inserting the piston into the fitting hole and speed of pulling the piston out of the restriction hole are variable according to changes of pressure, temperature and the like of operating oil supplied from a hydraulic pressure supply source. Accordingly, in a structure in which the angular phase of the driven side rotating member relative to the drive side rotating member is locked to the middle angular position when the piston is inserted into the fitting, hole or in a structure in which the angular phase of the driven side rotating member relative to the drive side rotating member is restricted within the angular range defined by opposite ends of the arc shaped restriction hole when the piston is inserted into the restriction hole, it sometimes happens that the piston passes the fitting or restriction hole before the piston is inserted into the hole or the piston is unlikely pulled out of the hole since the drive side rotating member excessively rotates relatively to the drive side rotating member before the piston has been pulled out of the hole.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a valve timing adjusting apparatus in which a lock piston can be fitted in or pulled out of a fitting hole without fail.
Another object of the present invention is to provide a valve timing adjusting apparatus in which a restriction piston can be inserted into or pulled out of a restriction hole without fail.
A further object of the present invention is to provide a method of controlling the valve timing adjusting apparatus.
To achieve the above object, a valve timing adjusting apparatus disposed between a drive shaft of an internal combustion engine and a driven shaft causing an opening and closing operation of at least one of an intake valve and an exhaust valve and operative to change an angular phase of the driven shaft relative to the drive shaft so that opening and closing timing of the at least one of an intake valve and an exhaust valve may be varied has drive and driven side rotating members, rotation control pressure chamber, a lock piston, a fitting hole and an angular phase locking pressure chamber.
The drive side rotating member is rotated together with the drive shaft. The driven side rotating member is rotated together with the driven shaft. The rotation control pressure chamber is operative to rotate the driven side rotating member relative to the drive side rotating member so that angular phase of the driven side rotating member relative to the drive side rotating member is controlled to a target position between the most retard angle position and the most advanced angle position in response to hydraulic pressure applied thereto. The lock piston is provided in one of the driven and drive side rotating members. The fitting hole is provided in the other of the driven and drive side rotating members. The angular phase locking pressure chamber is operative to execute one of first and second operations when hydraulic pressure is applied thereto and the other of the first and second operations when application of the hydraulic pressure thereto is released. The first operation is to insert the lock piston into the fitting hole so as to lock the angular phase of the driven side rotating member relative to the drive side rotating member to a middle position between the most retard angle position and the most advanced angle position, and the second operation is to pull the lock piston out of the fitting hole so as to release lock of the angular phase of the driven side rotating member relative to the drive side rotating member at the middle position.
With the valve timing adjusting apparatus mentioned above, a supply route of the hydraulic pressure to the rotation control pressure chamber is different from that to the angular phase l
Inoue Masaomi
Kusano Shigeyuki
Denion Thomas
Denso Corporation
Nixon & Vanderhye P.C.
Riddle Kyle
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