Plunger Design

The plunger is the pump cylinder.

Material selection is the same material as the main piston which can be used as plunger material.

Design analysis

Force on the plunger in compression force due to pressure

• Shear force in the hole
• If the length h_p is large relative to its diameter then the force may cause buckling
• Let us take f.s 2.3

Now to find the plunger lead thickness t_pl we use the following equation

 where t_pl = plunger lead thickness

d₂ = bore diameter of cylinder

p_max = 324.8Kpa

σ_all = 250Mpa/2.3 = 108.6Mpa

Tearing of the plunger at the hole due to vertical reaction force

The above equation of the tear area can be derived as follow,

As shown in the figure there is two possible tear areas

From Pythagoras tearoom

Considering the crushing of the material diameter of the plunger d_pl is given by:

Height of the piston,

• The inner seal is located 8mm below the upper surface of the plate a=8mm the thickness of the seal t is to be determined in seal design t_b = 15mm geometry analysis.
• Tb only value greater than 2t_s but less than t_b.