Abstract: A main journal 25a of a crank-shaped swinging shaft 25 which swings in a range of a predetermined angle is supported by bearing metals 51 and 52 each divided into two pieces. In supplying a lubrication oil through an oil bore 51b in the bearing metal 51 to a sliding surface of the main journal 25a and to inlet openings of lubrication oil passages P1 and P2 of the swinging shaft 25 open to the sliding surface, the inlet openings of the lubrication oil passages P1 and P2 of the swinging shaft 25 are designed so that they do not move past division portions 55 of the bearing metals 51 and 52 upon swing of the swinging shaft 25 in the range of the predetermined angle. Therefore, it is possible to prevent the lubrication oil to be supplied to the lubrication oil passages P1 and P2 from leaking from the division portions 55 of the bearing metals 51 and 52, thereby reliably lubricating a pin journal 25b of the swinging shaft 25 by the lubrication oil supplied from the lubrication oil passages P1 and P2.

Abstract: A humidity sensor is disposed near an HC adsorbent in an exhaust system of an internal combustion engine. After the internal combustion engine is shut off, it is detected whether or not the humidity sensor has failed based on the value of the humidity detected by the humidity sensor when the detected value of the humidity is substantially constant, by determining whether or not the detected value of the humidity falls in a range between upper and lower limit thresholds that are set depending on the temperature near the HC adsorbent. It is stably and easily detected whether or not the humidity sensor disposed near the HC adsorbent in the exhaust system of the internal combustion engine has failed.

Abstract: An exhaust gas valve device in an internal combustion engine, including a first bearing member mounted between a valve shaft and a valve body with one end of the valve shaft turnably fitted into the first bearing member, a second bearing member mounted between the valve shaft and the valve body with the other end of the valve shaft turnably passed through the second bearing member, and an actuator connected to the other end of the valve shaft protruding from the second bearing member. The valve body, the valve shaft and the first and second bearing members are formed of metal materials having equivalent thermal expansion coefficients; the first and second bearing members are press-fitted into said valve body; and a skin of a graphite-based solid lubricant is formed on a surface of the valve shaft in regions corresponding to the first and second bearing members.

Abstract: An exhaust gas purification system of internal combustion engine having a branch pipe coupled to the exhaust pipe through a flange and having a first cylindrical case constituting a bypass exhaust gas passage and a second cylindrical case constituting a main exhaust gas passage, whose flow are switched by a switch-over valve by selectively connecting the exhaust pipe to the main exhaust gas passage or the bypass exhaust gas passage, and an adsorbent installed in the bypass exhaust gas passage for adsorbing unburned components of the exhaust gas. The unburned exhaust gas components are recirculated to the air intake system through an EGR pipe. In the system, an inlet of the EGR pipe is formed integrally with the branch pipe flange, thereby enabling to prevent increase in fabrication step and cost and further to facilitate maintenance. Moreover, the first cylindrical case is made displace relative to the second cylindrical case.

Abstract: A gas jacket is provided in a lower portion of a cylinder block, so that an exhaust gas in an exhaust gas passage is supplied to the gas jacket through an exhaust gas supply passage having an exhaust gas supply valve. Fresh air in an intake passage is supplied to an intake passage through a fresh-air supply passage having a fresh-air supply valve. The temperature of a lower cylinder wall is controlled in a feedback manner to a target temperature for the lower cylinder wall. The target temperature for the lower cylinder wall is set at a sufficiently high temperature in a range in which an oil film of lubricating oil, extending from an intermediate portion of the cylinder wall to a bottom dead center of a piston, can be ensured. Therefore, the viscosity of the lubricating oil can be decreased to minimize the friction loss at slide portions of the cylinder wall and the piston, thereby providing an increase in engine output, a reduction in amount of fuel consumed and a reduction in lubricating oil consumed.

Abstract: A humidity sensor is disposed near an HC adsorbent in an exhaust system of an internal combustion engine. After the internal combustion engine is shut off, it is detected whether the humidity sensor has failed or not based on the value of the humidity detected by the humidity sensor when the detected value of the humidity is substantially constant, by determining the detected value of the humidity falls in a range between upper and lower limit thresholds that are set depending on the temperature near the HC adsorbent. It is stably and easily detected whether the humidity sensor disposed near the HC adsorbent in the exhaust system of the internal combustion engine has failed or not.

Abstract: In an exhaust gas valve device in an internal combustion engine, including a first bearing member mounted between a valve shaft and a valve body with one end of the valve shaft turnably fitted into the first bearing member, a second bearing member mounted between the valve shaft and the valve body with the other end of the valve shaft turnably passed through the second bearing member, and an actuator connected to the other end of the valve shaft protruding from the second bearing member, The valve body, the valve shaft and the first and second bearing members are formed of metal materials having equivalent thermal expansion coefficients; the first and second bearing members are press-fitted into said valve body; and a skin of a graphite-based solid lubricant is formed on a surface of the valve shaft 46 in regions corresponding to the first and second bearing members.

Abstract: An exhaust gas purification system of internal combustion engine having a branch pipe coupled to the exhaust pipe through a flange and having a first cylindrical case constituting a bypass exhaust gas passage and a second cylindrical case constituting a main exhaust gas passage, whose flow are switched by a switch-over valve by selectively connecting the exhaust pipe to the main exhaust gas passage or the bypass exhaust gas passage, and an adsorbent installed in the bypass exhaust gas passage for adsorbing unburned components of the exhaust gas. The unburned exhaust gas components are recirculated to the air intake system through an EGR pipe. In the system, an inlet of the EGR pipe is formed integrally with the branch pipe flange, thereby enabling to prevent increase in fabrication step and cost and further to facilitate maintenance. Moreover, the first cylindrical case is made displace relative to the second cylindrical case.