Patent ID: 8348644

Claim:
A pump comprising: a cylinder having an inner peripheral surface, wherein the cylinder defines an outlet-side passage therein; and a plunger that is reciprocably received within the cylinder, wherein: the plunger has an end surface; the inner peripheral surface of the cylinder and the end surface of the plunger define a pump chamber; the outlet-side passage of the cylinder is communicated with the pump chamber; and when the plunger reciprocates within the cylinder, fluid inside the pump chamber is pressurized such that fluid is discharged to an exterior of the pump through the outlet-side passage, wherein: the inner peripheral surface of the cylinder includes a spherical surface part that surrounds the pump chamber; the spherical surface part is defined by a curved surface having a predetermined curvature such that the pump chamber defines a spherical space; the spherical surface part is provided with an opening of the outlet-side passage; the opening of the outlet-side passage has a circular shape when observed from a spherical center of the pump chamber; the inner peripheral surface of the cylinder includes a plunger receiving hole part, a side surface of the plunger sliding on the plunger receiving hole part; the spherical surface part is formed such that the spherical space of the pump chamber has a spherical shape greater than a hemispherical shape; and the spherical space of the pump chamber has a diameter greater than a diameter of the plunger receiving hole part.