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Rotor stability of a rotary pumpRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Rotary Motor And Rotary Nonexpansible Chamber PumpRotor stability of a rotary pump description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060083642, Rotor stability of a rotary pump. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to improvements in the impeller or rotor stability of a rotary pump. BACKGROUND OF THE INVENTION [0002] Rotary pumps have used journal bearings to stabilise a spinning rotor or impeller. It has been noted that commonly the impeller rotates about a central axis within the pump housing and may whirl to the side of the housing when the impeller is rotated at high speeds with insufficient load and results in instability in relation to the rotation of the impeller. [0003] The impeller of the rotary blood pump disclosed within U.S. Pat. No. 6,227,797--Watterson et al. is hydrodynamically suspended and may under certain conditions the impeller or rotor may experience a touchdown event. A touchdown event is a situation where the impeller or rotor touches or contacts the inner walls of the pump housing. Touchdown of the impeller or rotor often leads to damaging the impeller, housing and/or the pumping fluid. If a touchdown event occurs in a rotary blood pump implanted in a patient, such an event may result in impaired pump performance that may result in complications for the patient. Touchdown may be avoided by increasing the stability of the impeller or rotor or increasing the stiffness and/or dampening of the impeller or rotor. [0004] U.S. Pat. No. 5,324,177--Golding et al describes a means for increasing impeller or rotor stability in a rotary pump. The impeller and/or rotor are biased by a load provided by additional load acting only in radial orientation in respect of the axis of rotation of the pump. This has the effect of offsetting the rotor and thus stabilising the rotor in only the radial direction. The arrangement disclosed in U.S. Pat. No. 5,324,177, may also tend to destabilise the impeller in relation to the axial positioning of the impeller. Additionally, the radial biasing of the impeller is only useful in situations where the motor stators of the pump are positioned radially in respect of the axis of rotation of the impeller. This may lead to a considerably increase in size of the overall pump. [0005] The present invention aims to at least address or ameliorate one or more of the above disadvantages associated with the abovementioned prior art. SUMMARY OF THE INVENTION [0006] In accordance with a first aspect the present invention consists in a rotary pump including an impeller rotatable within a housing; wherein a load is imposed on said impeller as it rotates, in a direction that is substantially parallel to the axis of rotation and wherein said load stabilises the motion of the impeller. [0007] Preferably said load is achieved by magnetically biasing said impeller. [0008] Preferably said pump includes a set of stators positioned below the impeller and said set of stators generates said load. [0009] Preferably the magnetically biasing of said impeller is achieved by at least one yoke. [0010] Preferably an angle formed between the upper and/or lower axial surfaces of the impeller are not parallel with the respective corresponding surface of the inner wall of the housing. [0011] Preferably said impeller is not circular and the inner walls of the housing are generally circular. [0012] Preferably said load prevents or limits the impeller from contacting the housing, when in use. [0013] Preferably said impeller is generally square shaped. [0014] Preferably said impeller includes a hydrodynamic bearing. [0015] Preferably said hydrodynamic bearing is formed by a taper on the surface of the impeller of between 10 .mu.m and 50 .mu.m. [0016] Preferably a gap of less than 250 .mu.m is formed between the impeller and the housing, when in use. [0017] Preferably said pump is for pumping blood. [0018] Preferably said pump is implantable within the body of a patient. [0019] In accordance with a second aspect the present invention consists in a rotary pump including an impeller rotatable within a housing; wherein impeller is hydrodynamically suspended and wherein an angle formed between the upper and/or lower axial surfaces of the impeller are not parallel with the respective corresponding surface of the inner wall of the housing. BRIEF DESCRIPTION OF DRAWINGS [0020] Embodiments of the present invention will now be described with reference to the accompanying drawing wherein: Continue reading about Rotor stability of a rotary pump... Full patent description for Rotor stability of a rotary pump Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Rotor stability of a rotary pump patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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