Pump
The present disclosure provides a pump including a cylinder, a plunger, a spring seat, a spring, and a stopper. The cylinder defines therein a cylinder hole. The plunger includes a shaft portion, a seat receiver, and a step surface. The spring biases the plunger in a second direction opposite to a first direction through the spring seat. The stopper includes an engaging portion. The engaging portion restricts, by engaging with the step surface, a movable range of the plunger in the second direction. The stopper defines therein an eccentric hole that has an inner diameter greater than an outer diameter of the step surface. The eccentric hole is eccentric with the plunger and opens through a portion of the stopper other than the engaging portion.
1. A pump comprising:
a cylinder that defines therein a cylinder hole;
a plunger that includes a shaft portion, a seat receiver, and a step surface, the shaft portion having a portion reciprocatably inserted into the cylinder hole to define a pump chamber, the seat receiver protruding radially outward of the plunger and being arranged at a first side of the shaft portion opposite to a second side of the shaft portion that is close to the pump chamber, the step surface being formed at a middle portion of the shaft portion, the plunger being moved in a first direction to pressurize a fluid in the pump chamber by a driving force applied to an end surface of the first side of the shaft portion;
a spring seat that has a plate shape and engages with the seat receiver;
a spring that biases the plunger in a second direction opposite to the first direction through the spring seat; and
a stopper that is fixed to the cylinder and includes an engaging portion, the engaging portion restricting, by engaging with the step surface, a movable range of the plunger in the second direction, wherein
the stopper defines therein an eccentric hole that has an inner diameter greater than an outer diameter of the step surface, and
the eccentric hole is eccentric with the plunger and opens through a portion of the stopper other than the engaging portion.
2. The pump according to claim 1 , wherein
the stopper is formed of a cylindrical portion and a bottom, and
the engaging portion and the eccentric hole are formed in the bottom of the stopper.
3. The pump according to claim 2 , wherein
the cylindrical portion of the stopper is joined to the cylinder.
4. The pump according to claim 1 , wherein
the shaft portion includes a jaw portion that protrudes radially outward of the shaft portion and that has an end surface serving as the step surface.
5. The pump according to claim 1 , wherein
the shaft portion includes a first shaft and a second shaft,
the first shaft has a portion reciprocatably inserted into the cylinder hole,
the second shaft is positioned outside of the cylinder hole and has a diameter less than that of the first shaft, and
the first shaft and the second shaft are connected at a boundary region that forms the step surface.