Fluid pump with flow impedance member

A fluid pump comprising:

• an inlet for introducing fluid into said fluid pump;
• an outlet for discharging said fluid from said fluid pump;
• a motor having an armature which rotates about an axis such that said armature is supported at one end by a first bearing and at a second end by a second bearing, said motor also having a stator which circumferentially surrounds said armature such that a fluid passage is defined radially between said armature and said stator through which said fluid flows from said inlet to said outlet;
• a pumping arrangement which is rotated by said armature and which pumps said fluid from said inlet to said outlet;
• a flow impedance member extending axially in said fluid passage which impedes circumferential flow of said fluid within said fluid passage, thereby generating a pressure gradient circumferentially within said fluid passage which applies a lateral force to said armature;
• wherein said flow impedance member is a lower flow impedance member which impedes circumferential flow of said fluid within said fluid passage, thereby generating a first pressure gradient circumferentially within said fluid passage which applies a lower lateral force to said armature, said fluid pump further comprising:
• an upper flow impedance member extending axially in said fluid passage which impedes circumferential flow of said fluid within said fluid passage, thereby generating a second pressure gradient circumferentially within said fluid passage which applies an upper lateral force to said armature;
• wherein said lower flow impedance member is located within said fluid passage at a different circumferential location than said upper flow impedance member;
• and
• wherein said lower flow impedance member extends axially within said fluid passage over a different axial range than said upper flow impedance member.