Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2002-07-29
2004-01-13
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090150, C123S090160
Reexamination Certificate
active
06675753
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application Nos. 2001-240269 and 2001-390981 filed in Japan on Aug. 8, 2001 and Dec. 25, 2001, respectively. The entirety of each of the above applications is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cam phase variable apparatus for varying the phase of a cam, which is driven to rotate by power of a driving rotary shaft in order to make it possible to control the operation timing of an object of operation by the cam with respect to the driving rotary shaft. More particularly, the present invention relates to a cam phase variable apparatus for varying, for example, the injection timing of a fuel injection apparatus or an opening or closing timing of an intake valve or an exhaust valve, which is operated by a cam driven to rotate by power of a crankshaft of an internal combustion engine.
2. Description of Background Art
Conventionally, one cam phase variable apparatus of the type mentioned is disclosed in the official gazette of, for example, Japanese Patent Publication No. Sho 63-30496. The cam phase variable apparatus is provided for a fuel injection apparatus of an internal combustion engine and includes a pair of helical gears having helical splines cut in the opposite directions to each other and provided on a driving shaft. A camshaft has a cam provided thereon for being driven to rotate by the driving shaft to operate a fuel control valve. Furthermore, a sleeve is held in meshing engagement with the helical gears. The sleeve is moved in an axial direction through a slip ring, which is driven to move in an axial direction by an actuator, such as an electric motor, to rotate the cam shaft and the driving shaft relative to each other to vary the phase between the cam shaft and the driving shaft. Thereby, the operation timing of the fuel control valve with respect to the driving shaft, i.e., the fuel injection timing, is varied.
Another cam phase variable apparatus as a valve timing adjustment apparatus for intake and exhaust valves of an internal combustion engine is disclosed in the official gazette of Japanese Patent Laid-Open No. Hei 11-223113. In the cam phase variable apparatus, a hydraulic chamber formed in a timing pulley driven to rotate by a crankshaft is partitioned into a delay angle hydraulic chamber and a lead angle hydraulic chamber by a vane member formed integrally with a camshaft. The vane member is rotated relative to the timing pulley by hydraulic pressure of operating oil supplied into or discharged from the delay angle hydraulic chamber and the lead angle hydraulic chamber to vary the phase of the cam shaft relative to the crankshaft. Thereby, the opening and closing timings of the intake and exhaust valves with respect to the crankshaft is varied.
Incidentally, in the cam phase variable apparatus which uses the helical gear, abrasion of the splines of the sleeve and the helical gears is liable to occur through contact between the splines when movement in an axial direction of the sleeve driven by the actuator is converted into relative rotation of the cam shaft and the driving shaft by the helical gears. Furthermore, because of play arising from the abrasion, it is difficult to keep good control accuracy of the cam phase with respect to the driving shaft over a long period of time.
In addition, in the cam phase variable apparatus, which uses the vane member driven hydraulically, it is necessary to form a hydraulic chamber or an oil path in the timing pulley and the camshaft. Furthermore, it is necessary to provide the timing pulley with a seal apparatus for keeping the operating oil in the hydraulic chamber in a high hydraulic pressure state. Thus, there is a drawback in that the timing pulley and the camshaft are very complicated in structure.
SUMMARY OF THE INVENTION
The present invention has been made in view of such a situation as described above. It is a common object of the present invention to provide a cam phase variable apparatus which can suppress the occurrence of play by abrasion at sliding portions of two rotatable members, which rotate relative to each other, to allow good accuracy in phase control to be kept over a long period of time without complicating the structure of the two rotatable members.
Furthermore, it is an object of the present invention to decrease the inertial mass of components of a cam phase variable apparatus which rotate together with a first rotatable member to suppress degradation of the responsibility of rotation of a cam to a driving rotary shaft.
Furthermore, it is an object of the present invention to achieve further augmentation of the accuracy in phase control and to achieve a further reduction in size of a cam phase variable apparatus in an axial direction.
According to a first aspect of the present invention, a cam phase variable apparatus is provided for rotating a driving side member formed from a driving rotary shaft or a rotatable member driven to rotate by power of the driving rotary shaft. A cam side member is formed from a cam driven to rotate by the power of the driving rotary shaft or a rotatable member rotated in synchronism with the cam relative to each other in order to vary the phase of the cam with respect to the driving rotary shaft. A support shaft is provided on a first rotatable member and is formed from one of the driving side member and the cam side member. A lever is supported for rocking motion around a center axial line on a plane intersecting with an axial line of rotation of the first rotatable member. A driving apparatus is provided for rocking the lever. The lever has a first operating arm for engaging with the driving apparatus and a second operating arm for engaging with a second rotatable member formed from the other of the driving side member and the cam side member. Furthermore, the lever transmits the power of the driving rotary shaft to the cam side member and provides relative rotation between the first rotatable member and the second rotatable member which commonly have the axial line of rotation when the lever is rocked by the driving apparatus.
According to the first aspect of the present invention, the phase of the cam with respect to the driving rotary shaft is varied when the lever supported for rocking motion on the first rotatable member through the support shaft and engaging at the second operating arm thereof with the second rotatable member is rocked by the driving apparatus, which engages with the first operating arm of the lever to provide relative rotation between the first rotatable member and the second rotatable member. As a result, the following effects are achieved. In particular, the lever supported for rocking motion on the support shaft can smoothly convert, through the rocking motion thereof, the driving force of the driving apparatus acting upon the first operating arm into a force acting in a direction in which the relative rotation is provided. Accordingly, the occurrence of abrasion at sliding portions on which the lever slides such as the support shaft and the engaging portion of the second rotatable member is suppressed, and good accuracy in phase control can be maintained over a long period of time. Furthermore, the relative rotation is performed through the lever, which is supported for rocking motion on the support shaft secured to the first rotatable member and engages with the engaging portion of the second rotatable member. This is different from the background art described hereinabove, wherein such relative rotation is provided making use of hydraulic pressure. Accordingly, the necessity for a seal apparatus and so forth is eliminated. Consequently, the structure of the first rotatable member and the second rotatable member can be made comparatively simple.
According to a second aspect of the present invention, the second operating arm and the second rotatable member engage with each other through contact of a spherical face of an enga
Birch & Stewart Kolasch & Birch, LLP
Denion Thomas
Honda Giken Kogyo Kabushiki Kaisha
Riddle Kyle
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