Gear Pump

A gear pump comprising:

• a housing;
• a pump chamber formed in the housing, the pump chamber having a high pressure chamber and a low pressure chamber;
• a gear disposed within the pump chamber, and arranged to rotate at least by a drive shaft;
• a side plate disposed adjacent to the gear, between a side surface of the gear and a wall of the pump chamber, the side plate having an annular recessed groove formed in a surface confronting the wall of the pump chamber, and the annular recessed groove having a bottom portion;
• and
• a seal member disposed in the annular recessed groove of the side plate, and arranged to separate the high pressure chamber and the low pressure chamber of the pump chamber, and to be pushed in a direction away from the bottom portion of the recessed groove by a pressure introduced from the high pressure chamber when the gear is driven.

A gear pump comprising:

• at least a pair of gears engaged with each other;
• a side plate disposed adjacent to the gears, the side plate including an annular recessed groove, and a shoulder portion;
• a housing disposed at a position to sandwich the side plate with the gear, and to confront the gear;
• a seal member disposed in the annular recessed groove of the side plate, and arranged to seal a gap between the housing and an end of the shoulder portion of the side plate, and to separate a low pressure chamber and a high pressure chamber formed in a radial direction of the gear;
• and
• a pressure introducing section arranged to transform the seal member by a pressure of the high pressure chamber in a direction toward the end of the shoulder portion.