Abstract: This invention is an armature and an armature driving device in which the armature is rotated around its axis so as to inhibit uneven wear from occurring between the armature and a housing. That is, an armature which is slidably provided within a housing filled with fluid and which divides the inside of the housing into two fluid chambers is further provided with a communicating hole that enables the fluid to pass between the two fluid chambers. This communicating hole is formed such that the fluid passing through the communicating hole and out from the armature when the armature slides flows out at an angle to, and to the side of, a center axis of the armature.

Abstract: This invention is an armature and an armature driving device in which the armature is rotated around its axis so as to inhibit uneven wear from occurring between the armature and a housing. That is, an armature which is slidably provided within a housing filled with fluid and which divides the inside of the housing into two fluid chambers is further provided with a communicating hole that enables the fluid to pass between the two fluid chambers. This communicating hole is formed such that the fluid passing through the communicating hole and out from the armature when the armature slides flows out at an angle to, and to the side of, a center axis of the armature.

Abstract: This invention is an armature and an armature driving device in which the armature is rotated around its axis so as to inhibit uneven wear from occurring between the armature and a housing. That is, an armature which is slidably provided within a housing filled with fluid and which divides the inside of the housing into two fluid chambers is further provided with a communicating hole that enables the fluid to pass between the two fluid chambers. This communicating hole is formed such that the fluid passing through the communicating hole and out from the armature when the armature slides flows out at an angle to, and to the side of, a center axis of the armature.

Abstract: A piston for an internal combustion engine includes a skirt portion configured so that a value S/(D * L) is in the range of 0.4-0.55, where L is a length of the skirt portion, D is a diameter of a cylinder bore, and S is an area of an image of the skirt portion when the skirt portion is projected onto a plane perpendicular to a direction connecting a pair of boss portions. This condition decreases the friction between the piston and the cylinder bore.

Abstract: A cylinder block for an internal combustion engine includes a bolt boss located between cylinders, the bolt boss being connected to a common wall portion of a siamese bore wall structure by a double bridge structure including a lower bridge and an upper bridge located above the lower bridge. Since a composite moment E.sub.0 acting on the bolt boss during the tightening of a head bolt is directed in a plane including the common wall portion, the composite moment can be born by the common wall portion which has a very large rigidity in a direction perpendicular to the row of cylinder bores. As a result, deformation of the bolt boss is suppressed, and deformation of the cylinder bore and inclination of the top deck are also effectively suppressed.

Abstract: A surge tank construction arranged in an intake system of a multicylinder internal combustion engine, the surge tank defining an expansion chamber having faced first and second inner walls. A tubular body in which a throttle valve is arranged is open to the expansion chamber at the first wall. A partition wall extends from the second wall toward the first wall and terminates at a position spaced therefrom so that portions of the expansion chamber divided by the partition wall and connected to the respective groups of cylinders are connected to each other.