Abstract: An optical measurement probe is a probe for guiding light generated from a measurement target to an appliance, and includes an optical window and an optical fiber. The optical window is formed in a columnar shape, one of end surfaces of which forms a reflection surface (tapered surface), the optical window transmitting light entering from an incident surface (flat surface) formed on a portion of an outer peripheral surface of the optical window, causing the light to be reflected by the reflection surface, and emitting the light from the other end surface. The optical fiber guides the light emitted from the other end surface of the optical window to the appliance.

Abstract: Light from a direction (D) different from a predetermined direction is reflected by a tapered surface (21) so as to enter an optical fiber (4) for guiding light entering along the predetermined direction to an appliance. Light from the desired direction (D) may thereby be reflected by the tapered surface (21) according to the angle of the tapered surface (21) and may be made to enter the optical fiber (4). Accordingly, even in a case where the installation position of an optical measurement probe (1) is limited, if the angle of the tapered surface (21) is appropriately set, light from the desired direction (D) may be made to enter the optical fiber (4).

Abstract: Light from a direction (D) different from a predetermined direction is reflected by a tapered surface (21) so as to enter an optical fiber (4) for guiding light entering along the predetermined direction to an appliance. Light from the desired direction (D) may thereby be reflected by the tapered surface (21) according to the angle of the tapered surface (21) and may be made to enter the optical fiber (4). Accordingly, even in a case where the installation position of an optical measurement probe (1) is limited, if the angle of the tapered surface (21) is appropriately set, light from the desired direction (D) may be made to enter the optical fiber (4).

Abstract: A cooling system for a water-cooled internal combustion engine includes a coolant flow circuit and a coolant return passage. The coolant flow circuit includes a water pump, a water jacket having a plurality of serially connected flow passages, an oil cooler, a radiator, and a pressure-regulating valve for discharging coolant to a reservoir tank when pressure of the coolant in the coolant flow circuit reaches a predetermined target value. The coolant return passage supplies coolant from the reservoir tank to the coolant flow circuit via a check valve, which only allows coolant to flow in one direction from the reservoir tank to the coolant flow circuit.

Abstract: A cooling system for a water-cooled internal combustion engine includes a coolant flow circuit and a coolant return passage. The coolant flow circuit includes a water pump, a water jacket having a plurality of serially connected flow passages, an oil cooler, a radiator, and a pressure-regulating valve for discharging coolant to a reservoir tank when pressure of the coolant in the coolant flow circuit reaches a predetermined target value. The coolant return passage supplies coolant from the reservoir tank to the coolant flow circuit via a check valve, which only allows coolant to flow in one direction from the reservoir tank to the coolant flow circuit.