Abstract: To reduce a friction, and to provide an excellent seizing resistance. Provided is a cast iron cylinder liner including an inner peripheral sliding surface made of cast iron, and an internal combustion engine including a cylinder bore including an inner peripheral sliding surface made of cast iron, wherein the inner peripheral sliding surface includes a region satisfying Expression (1) to Expression (3), Rvk/Rk?1.0 ??Expression (1) 0.08 ?m?Rk?0.3 ?m Expression (2) Rk?Rpk>0 Expression (3) [Rk is the core roughness depth based on JIS B0671-2:2002, Rpk is the reduced peak height based on JIS B0671-2:2002, and Rvk is the reduced valley depth based on JIS B0671-2:2002 in Expression (1) to Expression (3)].

Abstract: An ultrasonic sensor includes a cylindrical case with a bottom. A piezoelectric element is bonded to an inner side of a bottom portion of the case, and a felt is bonded to the piezoelectric element. A cap is fitted to an opening of the case. The cap includes a fixing portion and a substrate which is harder than the fixing portion. Terminals are press-fitted to the substrate. Wires are connected to the terminals, so that the terminals are electrically connected to the piezoelectric element. A through hole is provided in the fixing portion. Resin before being foamed is injected from the through hole and then foamed, so that the case is filled with foamable resin while an excess amount of foamable resin is pushed out from the through hole.

Abstract: An ultrasonic sensor includes a cylindrical case with a bottom. A piezoelectric element is bonded to an inner side of a bottom portion of the case, and a felt is bonded to the piezoelectric element. A cap is fitted to an opening of the case. The cap includes a fixing portion and a substrate which is harder than the fixing portion. Terminals are press-fitted to the substrate. Wires are connected to the terminals, so that the terminals are electrically connected to the piezoelectric element. A through hole is provided in the fixing portion. Resin before being foamed is injected from the through hole and then foamed, so that the case is filled with foamable resin while an excess amount of foamable resin is pushed out from the through hole.

Abstract: An ultrasonic transmitting and receiving apparatus includes a casing, a vibration isolating member, and a piezoelectric element. The casing has a bottom, an inner peripheral wall, and an outer peripheral wall, and these components are integral and define a monolithic structure. The inner peripheral wall and the bottom define a first recess. The outer peripheral wall, the inner peripheral wall, and the bottom define a second recess. The second recess is filled with the vibration isolating member. The piezoelectric element is fixed on the bottom facing the first recess in the casing.

Abstract: An ultrasonic wave transmitter/receiver is provided in which the transmission/reception range thereof in at least one direction is relatively narrow, and which has stable reverberation characteristics. When the thickness of a thick-walled portion is t1, the thickness of each of thin-walled portions is t2, the thickness of a side portion provided continuously with the thin-walled portion is A, x=t2/t1, and y=A/t2, this ultrasonic wave transmitter/receiver is formed so that x and y are within the range defined by the following equations: 0.50≦x≦0.64 0.75y≦1.

Abstract: An ultrasonic wave transmitter/receiver is provided in which the transmission/reception range thereof in at least one direction is relatively narrow, and which has stable reverberation characteristics.

Abstract: An ultrasonic sensor includes a case member and a piezoelectric element. The case member has a hollow therein and a bottom portion provided at one end of the hollow. The bottom portion has a thick portion which extends along a first direction and a pair of thin portions which have a smaller thickness than the thick portion and are provided on opposite sides of the bottom portion along a second direction. The piezoelectric element radiates and/or detects ultrasonic energy and is provided at a center of the thick portion on an inner surface of the bottom portion.