An electric variable valve timing apparatus includes a sprocket unit and an electric motor. The electric motor is fixed to a chain cover with bolts. The chain cover includes plural bosses each having an internal thread to which one of the bolts is threaded. The bosses extend from the chain cover toward the sprocket unit to positions at which the bosses face an outer periphery of the sprocket unit in a radial direction. The bosses are arranged such that, when the sprocket unit moves downward from an attaching position, at which the sprocket unit is attached to the camshaft, at least two bosses are engaged with the sprocket unit to restrict downward movement of the sprocket unit, and that the sprocket unit is allowed to move between a location outside of a space covered by the chain cover and the attaching position.

A cylinder head for an internal combustion engine with an exhaust aftertreatment arrangement includes a cylinder head base body, a valve cover connected to the cylinder head base body, and a carrier element for supporting the exhaust aftertreatment arrangement. The carrier element is supported against the cylinder head base body via a stud. The stud extends through the valve cover.

In a single cylinder internal combustion engine in which a plug hole is provided striding between a cylinder head and a head cover, and an intake side camshaft and an exhaust side camshaft are disposed at positions sandwiching the plug hole therebetween, a long hole portion formed long in a direction orthogonal to axes of the camshafts is formed as a part of the plug hole. A part of a plurality of cam holder attaching bolts used for fastening the cam holder to the cylinder head are disposed within the long hole portion. A breather chamber disposed around the long hole portion is formed between the head cover and a breather plate attached thereto.

A cylinder head bolt inserted into a cylinder head is threadingly engaged with an engine casing comprised of a cylinder and a crankcase to tighten the cylinder head and the engine casing firmly together. Between a rotation operating part, which is provided in a head of the cylinder head bolt, and an upper surface of the cylinder head, a plain washer and a spring member placed thereabove are interposed. The spring member is capable of exerting an axially acting spring force. A first frictional resistance between the rotation operating part and the spring member is so chosen to be lower than a second frictional resistance between the spring member and the plain washer and a third frictional resistance between the plain washer and a bearing surface on the cylinder head.

A cylinder block (1) includes a main block body (2) made of a metal material and an outer member (3) made of a resin material and welded to the main block body (2). The main block body (2) has a cylinder wall (13) defining therein a cylinder bore (16) and a second columnar part (14B) formed at a position apart from the cylinder wall (13). The outer member (3) has a second columnar part insertion hole (53) and defines a water jacket between the outer member (3) and the cylinder wall (13). The second columnar part (14B) is placed in the second columnar part insertion hole (53) with a predetermined clearance left between the second columnar part insertion hole (53) and the second columnar part (14B), in a state of being isolated from the water jacket, and extends to a cylinder head.

An upper structure of an engine in which secondary air is supplied to an exhaust port of an engine. The upper structure includes: a cylinder head in which an exhaust camshaft and an intake camshaft are installed; a cylinder head cover fixed on the cylinder head by fastening members; a reed valve configured to prevent backflow of exhaust gas from the exhaust port to an upstream side; and an ignition plug positioned between the intake camshaft and the exhaust camshaft. An accommodating portion for accommodating the reed valve is provided adjacent to the ignition plug above the exhaust camshaft in the cylinder head cover. A supply path for introducing secondary air from the accommodating portion to the exhaust port is formed on an opposite side of the cylinder head cover from the ignition plug across the exhaust camshaft.

An upper structure of an engine in which secondary air is supplied to an exhaust port of an engine. The upper structure includes: a cylinder head in which an exhaust camshaft and an intake camshaft are installed; a cylinder head cover fixed on the cylinder head by fastening members; a reed valve configured to prevent backflow of exhaust gas from the exhaust port to an upstream side; and an ignition plug positioned between the intake camshaft and the exhaust camshaft. An accommodating portion for accommodating the reed valve is provided adjacent to the ignition plug above the exhaust camshaft in the cylinder head cover. A supply path for introducing secondary air from the accommodating portion to the exhaust port is formed on an opposite side of the cylinder head cover from the ignition plug across the exhaust camshaft.

A hood module for attachment on a cylinder head of an internal combustion engine may include a hood body comprised of plastic and a bearing bracket comprised of metal as a rotatable holder for a camshaft in the hood module. The bearing bracket may be attached to the hood body with position accuracy by a joint connection so that the bearing bracket is aligned for attachment on the cylinder head through the hood body. In some examples, a joint element in the form of a sleeve may be used as part of the joint connection between the bearing bracket and the hood body.

A device for rotatable mounting of a camshaft of an internal combustion engine. The device includes a first bearing body with a receiver for rotatable mounting of the camshaft. The device has a cylinder head or a fixing frame for fixing the first bearing body. The device has a first fixing means which fixes the first bearing body to the cylinder head or fixing frame. The first fixing means is the sole fixing means which fixes the first bearing body to the cylinder head or fixing frame.

A method for manufacturing an engine block is disclosed. In embodiments, the method includes forming an expansion hole in a block body of the engine block that encircles an engine block bore at a head face of the engine block. The method also includes placing an insert into the expansion hole, the insert including an insert body. The method further includes placing a reaction material between the insert and the block body. The method yet further includes forming an insert bond layer between the insert and block body using the reaction material. The method still further includes forming an insert bore through the insert body.