HYDRAULIC POWER STEERING SYSTEM HAVING NOISE REDUCING MEANS

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic power steering system including a gear pump having a means for reducing noise caused by the fluctuation of pressure produced at the time of gear rotation. SOLUTION: A hydraulic power steering system includes a reservoir 14 for housing a hydraulic fluid 68, a gear pump 16 having a suction hole 74 and a hydraulic muffler 18. The gear pump 16 has a gear 78 having an meshing gear 80 for carrying the flow of the hydraulic fluid 68 from the reservoir 14 through the suction hole 74 into the pump 16. The muffler 18 reduces noise by suppressing the fluctuation of the rate of a flow generated by the meshing gear 80. The muffler 18 includes a compliant element 92 and a fluid inertial structure 92 arranged between the suction hole 74 and the fluid 68 in the reservoir 14. The inertial structure 90 responds to the fluctuation of a flow rate by directing corresponding liquid pressure fluctuation so as to deform the compliant element 92. Thus, noise are reduced at the time of deformation of the compliant element 92.