Helical gear pump or gear motor with optimal relief grooves for trapped fluid

A gear pump or gear motor comprising

• a pair of intermeshing driving and driven helical gears, a housing surrounding said gears and providing pressure ports and suction ports leading to said gears,
• pressure port connected and suction port connected relief grooves, formed in the meshing area in the housing and/or the stationary parts, positioned in the pump,
• said relief grooves facing the lateral faces of the helical gears;
• said pressure port connected and suction port connected relief grooves at the leading lateral face of the helical gears having been shifted, out of the symmetrical position with respect to the plane through the two rotation axes, over a distance V/2 in the direction of the suction port,
• said pressure port connected and suction port connected relief grooves at the lagging lateral face of the helical gears having been shifted, out of the symmetrical position with respect to the plane through the two rotation axes, over a distance V/2 in the direction of the pressure port,
• said distance V/2 having been given that value, that an enclosed tooth cavity is connected via the pressure port connected relief grooves with the pressure port, only with decreasing size of the area of the enclosed tooth cavity, considered in the transversal plane through the middle of the gears and that an enclosed tooth cavity is connected via the suction port connected relief grooves with the suction port, only with increasing size of the area of the enclosed tooth cavity, considered in the transversal plane through the middle of the gears.