Honda Giken Kogyo Kabushiki Kaisha

Honda Motor Co., Ltd.

Other

Honda Giken Kogyo Kabushiki

Chikara Tanaka

Noriyuki Yamada

Junichi Iwamoto

Hiromu Nakamura

Kaori Takehana

Atsushi Takahashi

Jiro Takagi

Yukio Konishi

Takeya Harada

Hirokazu Ohsaki

Takaaki Harasaki

Koji Tsuchida

Masayasu Tajima

A variable valve actuation device includes a plurality of valve lifter. Each valve lifter slidable in a lifter support hole between an upper position and a lower position. A valve rest recess communicating with a valve rest chamber opens out at an outer circumferential surface of the valve lifter, and a valve rest supply port of a valve rest passage opens out at an inner circumferential surface of the lifter support hole in such a positional relationship that the valve rest passage and the valve rest chamber communicate with each other when the valve lifter is at the upper position, and continue to communicate with each other until the valve lifter has moved downward to a shut-off position located at a prescribed part of a down stroke from the upper position. The communication between the valve rest passage and the valve rest chamber shut off at the shut-off position.

Variable valve actuation device for internal combustion engine

The variable valve actuating device () comprises a switch pin () slidably received in the valve lifter () so as to selectively abut the end surface of the valve stem as the valve lifter is actuated by the cam. The device further comprises a first spring retainer () attached to an intermediate part of the valve stem () to engage a first valve spring (), and a second spring retainer () slidably engaged by an end part of the valve stem to engage a second valve spring (). The valve stem is provided with a stem end () which is enlarged with respect to a part of the valve stem slidably engaging the second spring retainer so as to define a shoulder surface () that engages the second spring retainer against a spring force of the second valve spring.

Variable valve mechanism for internal combustion engine

The present invention provides a valve operating system for internal combustion engines, having a roller rolling contacting a valve operating cam, the system being provided with an oil supply passage capable of reducing a pressure loss to a low level even when a flow rate of lubricating oil entering the oil supply passage increases in accordance with a heightened engine speed, improving the lubricating ability with respect to the roller, and attaining a long lifetime of a rocker arm. This valve operating system includes a rocker arm support member provided with an oil passage in an inner portion thereof, a cam shaft provided on a valve operating cam, and a rocker arm which is provided with a roller rolling contacting the valve operating cam, and which is provided in an inner portion thereof with an oil supply passage for supplying a lubricating oil from the rocker arm support member to the roller, the sectional area of the flow passage of the oil supply passage increasing gradually from an opening thereof on the side of the roller toward an opening thereof on the side of the rocker arm support member.

Valve operating system for internal combustion engines

A valve operating system in an internal combustion engine includes an associative-operation switchover means capable of switching over the associative operation of a pair of rocker arms disposed adjacent each other and the releasing of the associative-operation. The associative-operation switchover means is provided between a plurality of rocker arms including the rocker arms disposed adjacent each other. In such valve operating system, through-bores are coaxially provided in support walls of the rocker arm, and opposite ends of a roller shaft are fitted and fixed in the through-bores. A spring-receiving member is mounted to the roller shaft for receiving a return spring. Thus, when the roller shaft with the return spring of the associative-operation switchover means accommodated therein is mounted to the rocker arm, it is possible to facilitate the processing and to reduce the size and weight of the rocker arm.

Valve operating system in internal combustion engine

In a valve operating system in an internal combustion engine, a swinging support section provided at a base end of a rocker arm is swingably carried on a rocker shaft mounted in a cylinder head. A plurality of valve abutments are provided at a tip end of the rocker arm and capable of being individually put into abutment against upper ends of a plurality of engine valves, and a cam abutment is provided on the rocker arm in an intermediate portion between the swinging support section and each of the valve abutments to come into contact with a valve operating cam. The swinging support section comprises a thinner cylindrical portion surrounding the rocker shaft, and thicker cylindrical portions which are formed at a thickness larger than that of the thinner cylindrical portion into a cylindrical shape to surround the rocker shaft and which are integrally and continuously provided at axially opposite ends of the thinner cylindrical portion, respectively. Thus, it is possible to enhance the durability of the rocker arm, while avoiding an increase in weight of the rocker arm.

In a valve operating system in an internal combustion engine, a swinging support section provided at a base end of a rocker arm is swingably carried on a rocker shaft, and tappet screws are threadedly fitted in a plurality of boss portions formed at a tip end of the rocker arm and arranged in a direction parallel to an axis of the rocker shaft, so that they can be individually put into abutment against upper ends of a plurality of engine valves. Cam abutments are provided on the rocker arm in an intermediate portion between the swinging support section and the boss portions to come into contact with a valve operating cam. The boss portions are interconnected by a connection wall having a plurality of wall portions which intersect each other in a plane perpendicular to the axis of the rocker shaft. Thus, the rigidity of the tip end of the rocker arm is enhanced sufficiently.

In a valve operating system in an internal combustion engine, a rocker arm has a plurality of valve abutments provided thereon and capable of being individually put into abutment against upper ends of a plurality of engine valves cam abutments, and also has cam abutments provided thereon to come into contact with a valve operating cam. Wall-removed portions are formed in the rocker arm at locations corresponding to the cam abutments and open at opposite sides of the rocker arm. Thus, it is possible to provide a reduction in weight of the rocker arm.

A valve operating system in an internal combustion engine includes a switchover pin which is movable between an associatively operating position where adjacent ones of rocker arms are operated in association with each other, and an associative-operation releasing position where the associative-operation is released, the switchover pin receiving at axially opposite ends thereof a hydraulic pressure force acting toward the associatively operating position and a spring force acting toward the associative-operation releasing position, a cylindrical roller shaft which is fixed to one of the adjacent rocker arms, and into which the switchover pin is slidably fitted in response to the movement thereof toward the associatively operating position, and a roller rotatably carried on the roller shaft to come into rolling contact with a cam provided on a camshaft. In this valve operating system, at least one of axially opposite end surfaces of the roller shaft formed of a material harder than that of the one rocker arm, which receives the switchover pin, protrudes from a side surface of the one rocker arm. Thus, a wear powder can be prevented from entering into the roller shaft, thereby ensuring the smooth switching-over operation of the switchover pin.

One of adjacent rocker arms in a valve operating system of an engine is provided with first and second support walls. A roller is disposed between the first and second support walls to come into rolling contact with cams. A cylindrical roller shaft, supporting the roller, is provided between the first and second support walls, so that a switchover pin of an associative-operation switchover means can be slidably fitted into the roller shaft in response to the movement thereof. The roller shaft is press-fitted into at least a second one of the first and second support walls, and a press-fit margin for the roller shaft press-fitted into the second support wall on the side of the other rocker arm is set smaller than a press-fit margin for the roller shaft press-fitted into the second support wall on the side of the roller.

In an engine including a variable timing/lift mechanism for an intake valve, journal portions of a valve-operating cam shaft are supported on cam bearing portions integrally provided in a cylinder head, and an intake rocker shaft is fixed by bolts to rocker shaft fixing portions provided on an upper surface of the cam bearing portions. By bringing opposite sides of intake rocker arms swingably supported on the intake rocker shaft into slidable abutment against positioning faces integrally formed on opposite sides of the cam bearing portions, the intake rocker arms are positioned in a thrust direction. Thus, it is possible to accurately and easily position the intake rocker arms in the thrust direction without the need for a special member.

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Wako, Japan

Chikara Tanaka