Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Mitsubishi Jidosha Engineering Kabushiki Kaisha

Toshihiko Oka

Shinichi Murata

Norio Takayasu

Masanori Tokuhisa

Kazuki Yagi

Shuji Nagano

Tetsushi Nagira

Kenichi Morishima

Hayato Sugimura

Koichi Yoshimoto

Nobuhiro Kawakami

Satoshi Matsui

Satoshi Ando

Keisuke Komura

Yoshinori Sakurai

Masahiko Kubo

Akira Yoshihara

Yusuke Kido

Takao Ichimura

Akimasa Yamamoto

In a cylinder head () having a built-in exhaust manifold () of an engine (), outer coolant passages (A andB) in which an engine coolant circulates are provided, and are disposed along the manifold positioned at a side of an outer surface (C) of the cylinder head (). Further, inner coolant passages (A andB) having shapes which are branched from the outer coolant passages (A andB) and then join are provided, and are disposed along the outer coolant passages (A andB) and at an inner side of the cylinder head ().

Cylinder head of engine

An engine includes a side wall, a head cover, and a cam cover. The cam cover is disposed obliquely relative to the side wall. The cam cover has a seal line that seals up a gap between the head cover and the cam cover. The engine further includes a cam cap fixed to an upper surface of the side wall to support a camshaft so as to be rotatable between the side wall and itself.

Engine

An engine includes: an oil control valve built in a cylinder head, and configured to control a pressure of oil to be supplied to a variable valve mechanism via a camshaft; and a cam cap fixed to an upper face of the cylinder head, and configured to rotatably support the camshaft between the cam cap and the cylinder head, as a flow passage for the oil to be force-fed from an oil pump to the oil control valve, the cam cap including: a lateral passage formed inside the cam cap, and extended in a direction along the upper face of the cylinder head; and a downward passage extended downward from the lateral passage so as to serve as a downstream side flow passage of the lateral passage, and configured to guide the oil toward the oil control valve.

A cam structure driving a tappet having a crowning on a top face and connected to a base end section of an intake or exhaust valve of an engine, includes: a camshaft rotating in synchronization with a crankshaft of the engine; a cam lobe mounted on the camshaft, and including: a base cam including: a base circular section having a mounting hole for the camshaft; and a valve lift section having a cut-out section in a tip end portion; and a roller provided in the cut-out section and having a cylindrical section with a constant diameter. A center section in a width direction of the base cam makes contact with the tappet at a position deviated from a center of the top face of the tappet, and the cylindrical section makes contact with the center of the top face of the tappet.

Cam structure

A cylinder head includes: a bottom wall; an outer circumferential wall defining inside thereof a disposition space where valves which open and close combustion chambers, rocker arms, a camshaft which actuates the rocker arms, and a rocker arm shaft which supports the rocker arms are disposed; a longitudinal; a lateral wall, integrally formed with the longitudinal wall and the outer circumferential wall; a camshaft support, formed on the lateral wall; a rocker arm shaft support, formed on the lateral wall in such a manner that a height of the rocker arm shaft is shifted from a height of the camshaft; and a head bolt boss, formed on the bottom wall to overlap the lateral wall in a height direction. The lateral wall includes a passage through which a head bolt is passed into the head bolt boss and which overlaps the head bolt boss in the height direction.

Cylinder head

A cylinder head includes: a bottom wall portion; an outer circumferential wall portion defining inside thereof a space; a longitudinal wall portion extending to define, in the space, an intake side where an intake camshaft is disposed and an exhaust side where an exhaust camshaft is disposed; first lateral wall portions disposed on the intake side, on which first support portions are formed for supporting the intake camshaft thereon; second lateral wall portions disposed on the intake side, on which second support portions are formed for supporting the variable valve actuating units thereon; and third lateral wall portions disposed on the exhaust side, on which third support portions are formed for supporting the exhaust camshaft thereon. The second lateral wall portions are lower than the first lateral wall portions in a height direction from the bottom wall portion. The third lateral wall portions are higher than the second lateral wall portions in the height direction. A face of the bottom wall portion which is disposed on the exhaust side is higher than a face of the bottom wall portion which is disposed on the intake side, in the height direction.

There is provided a valve system for an internal combustion engine, in which a rocker shaft required to have a higher stiffness has a larger diameter. A rocker shaft on an intake side is formed to have a larger diameter than that of a rocker shaft on an exhaust side, and therefore, it is possible to ensure such stiffness as to compensate for an excess in weight and to improve valve operating characteristics of a valve system.

Valve system for internal combustion engine

A pair of exhaust ports () have flat portions () formed on respective inner peripheral surfaces thereof and facing in directions opposite to each other. An intervening cooling water passage () is formed between the flat portions () when a cylinder head () is cast.

Cooling water passage structure for an engine

The bottom surfaceof the cylinder headis formed by an intake-side bottom surfaceand an exhaust-side bottom surfaceon which an intake portand an exhaust portare formed respectively. Further, a first wallformed between an intake-side water jacketand the intake-side bottom surfaceis larger in thickness than a second wallformed between an exhaust-side water jacketand the exhaust-side bottom surface. This structure can reduce an amount of HC included in exhaust gas.

Cylinder head structure

A valve gear for an internal combustion engine capable of promptly switching the position of a piston in a rocker arm to thereby change the engine operating condition with a satisfactory response, even in a low rotation region in which an adequate amount of oil discharged from an oil pump cannot be expected. Depending on positions of pistons slidably fitted in low-speed and high-speed cylinder portions provided in an intake driven rocker arm, a low-speed or high-speed drive rocker arm is selectively operated to press a corresponding one of the pistons. The piston in the low-speed cylinder portion switched in a low rotation region is made smaller in diameter than the piston in the high-speed cylinder portion, to be enabled to be promptly switched.

Valve gear of an internal combustion engine

A valve gear with a cylinder suspending mechanism of an internal combustion engine, whose entire valve gear mechanism is downsized by efficiently arranging the configuration of the valve gear including the cylinder suspending mechanism. A low-speed drive rocker arm and a high-speed drive rocker arm are disposed in front and at the rear of an intake driven rocker arm so that pistons of low-speed and high-speed cylinder portions arranged side by side in the intake driven rocker arm may be pressed by operating operation arm portions extending from the respective drive rocker arms, to thereby arrange the low-speed and high-speed cylinder portions and the low-speed and high-speed drive rocker arms around the intake driven rocker arm to gather in one place.

Valve gear with cylinder suspending mechanism of an internal combustion engine

A valve system for an internal combustion engine in which accumulating means can be provided without deteriorating the ease of assembly is provided. A variable valve control mechanism provides control to selectively open and close intake valves and exhaust valves. Pressurized oil supplied to the variable valve control mechanism is accumulated in an accumulator. The body of the accumulator is inserted into and fixed in a hole of a cylinder head. The length of a gap formed between the upper part of the body of the accumulator and a flat plate is set to be shorter than the length of a screw part of the body of the accumulator. Therefore, the accumulator can be replaced and maintained easily, and can be prevented from falling off.

A plurality of oil passages are formed in a shaft body of a rocker shaft, which partially constitutes a valve drive system of an internal combustion engine. A bolt hole is formed in the shaft body in such a manner as to substantially perpendicularly intersect the axis of the shaft body. A bush is fitted into the bolt hole in such a manner as to prevent the bolt hole from establishing communication between the plurality of oil passages. A bolt is fastened through the bush to thereby fix the rocker shaft on a cylinder head. This structure improves the support rigidity of the rocker shaft and the dynamic characteristics of the valve drive system, and reduces the number of components and the number of working man-hours.

Rocker shaft

A valve system for an internal combustion engine has first rocker arms supported by a rocker shaft such that they rock when driven by first cams; a second rocker arm supported by the rocker shaft such that it rocks when driven by a second cam, the second rocker arm being disposed adjacent to the first rocker arms; a connection switching mechanism that switches the first rocker arms between a state of being connected to the second rocker arm and a state of being disconnected from the second rocker arm; a forcing member that forces the second rocker arm toward the second cam while the second rocker arm is rocking; a supporting member rotatably supported by a support shaft provided on a cylinder head to support the forcing member; and a locking structure that inhibits the supporting member from rotating about the support shaft.

To provide a flow path structure of a hollow tube capable of reducing facility cost and product cost by promoting assembling operability, a rocker shaft is constituted by including a tubular member having a hollow portion and a partitioning member interposed at the hollow portion of the tubular member for partitioning the hollow portion into a plurality of flow paths along an axial direction and the partitioning member is constituted by a plate member including a partitioning portion for partitioning the hollow portion into the flow paths along the axial direction and a close contact portion brought into close contact with an inner face of the tubular member.

Growing community of inventors

Anjyo, Japan

Toshihiko Oka