Pumps – Expansible chamber type – Having pulsation dampening fluid receiving space
Reexamination Certificate
2003-05-20
2004-06-15
Vrablik, John J. (Department: 3748)
Pumps
Expansible chamber type
Having pulsation dampening fluid receiving space
C417S540000, C418S132000, C418S135000, C418S147000, C418S235000, C418S256000
Reexamination Certificate
active
06749411
ABSTRACT:
BACKGROUND OF THE INVENTION
For certain power distribution applications transmission of mechanical energy by hydraulic manipulation is preferable to other options for reasons of power density, arrangement flexibility, and controllability. At the present time, machines employed for the hydraulic transmission of mechanical energy primarily consist of hydraulic pumps and hydraulic motors employing reciprocating mechanical motion of pistons and valves to accomplish movement of pressurized working fluid. Due to reciprocation of primary function components the working fluid flow inherently involves the presence of pressure fluctuations and hence inherently feature the potential for propagation of undesirable noise and mechanical vibration. Hydraulic power systems featuring relatively high measures of working fluid pressure and relatively low measures of working fluid flow velocity are often identified as “hydrostatic” power systems.
Over a number of years significant inventive effort has been directed toward the derivation of a “rotary” fluid displacement machine employing only rotationally dynamic mechanical components for working fluid manipulation. In comparison with reciprocating machines the rotary machine is perceived to offer advantages in terms of mechanical simplification and elimination of fluid flow pressure fluctuations. The radial vane type rotary machine has been the subject of particular attention in this regard.
Conceptually the rotary vane machine features a stationary hollow containment structure consisting of a containment cylinder with a precisely or approximately circular bore and with an end closure structure installed at each axial end. Said containment structure is fitted with ports for induction and discharge of working fluid through the structural boundary. A rotational armature approximately circular in cross-section and concentrically secured on a rotational shaft is installed within the bore of said containment cylinder. The diameter of said rotational armature is proportioned to create an annular cavity between the peripheral surface of said rotational armature and the bore of said containment cylinder. Said rotational shaft axially extends through the axial length of said containment structure and is radially constrained by rotational bearings. Axial ends of said rotational shaft are configured as necessary to interface with external rotational power systems. Said rotational shaft is aligned with its rotational axis parallel to but radially separated from the bore axis of said containment cylinder. Said rotational armature accommodates an axially aligned radial vane slot at each of several centers equally spaced around its periphery and said radial vane slot is proportioned to accommodate and provide sliding support for one radial vane. Said radial vane is axially proportioned to extend through the axial length of said rotational armature and radially proportioned to extend from within said radial vane slot to interface with the bore of said containment cylinder. Collectively the radial vanes subdivide said annular cavity into a number of annular segmental chambers. Since the rotational axis of said rotational shaft is radially separated from the bore axis of said containment cylinder the volume of each annular segmental chamber is dependent upon its rotational position and is cyclically manipulated upon rotation of said rotational armature. The cyclical relationship between annular segmental chamber volume and rotation of said rotational armature equates to the cyclical relationship between contained volume and piston movement featured in reciprocating type fluid displacement machines.
A number of patents have been awarded for rotary vane hydraulic power machine concepts however as of this writing none of the concepts presented in prior art are known to have matured sufficiently to demonstrate adequacy regarding one or more practical functional viability parameters. Functional viability of energy transmission machines is measured by their capability to meet thresholds for efficiency and power density within constraints imposed by natural physical phenomena.
The efficiency and power density of hydraulic rotational power machines are directly influenced by machine capabilities defined in terms of volume cycle efficiency, pressure cycle efficiency, mechanical efficiency, working fluid pressure amplification, and rotational velocity.
For rotary vane type machines volume cycle efficiency is directly related to the proportional relationship between the internal bore diameter of the containment structure and the diameter of the internal rotational armature. Pressure cycle efficiency is directly influenced by both the number of segmental chambers surrounding said rotational armature and the distance separating the rotational axis of said rotational armature from the bore axis of said containment structure. Pressure cycle efficiency is inversely influenced the relative thickness of the radial vanes and by hydrodynamic impedance imposed on the movement of working fluid as required to accomplish the cyclical manipulation.
Analysis demonstrates that the threshold for adequate pressure cycle efficiency is attained only when the number of segmental chambers surrounding said rotational armature exceeds a certain minimum value. However the radial vanes are, collectively, a potentially significant cause of degradation in mechanical efficiency due to frictional resistance at sliding interfaces. Additionally the radial vanes are, collectively, a potentially significant cause of degradation in mechanical efficiency if ancillary pumping of working fluid is incurred by reciprocating motion of the radial vane within the radial vane slot. For these reasons functional viability is dependent upon derivation the optimum balance between several efficiency considerations.
In addition to the efficiency considerations discussed above, power density is directly influenced the magnitude of working fluid pressure amplification, and the magnitude of rotational velocity. However hydraulic machines function by manipulation of an essentially non-compressible working fluid and so entail the possible occurrence of noise, vibration, and efficiency degradation due to high-pressure hydrodynamic impacting and low-pressure hydrodynamic cavitation. For these reasons acceptable limits for working fluid pressure amplification and rotational velocity and technical approaches for avoidance of hydrodynamic impacting and hydrodynamic cavitation phenomena are also functional viability considerations.
The principal features of several rotary vane type hydraulic machines presented in prior patent disclosures are reviewed below.
U.K. Pat. No. 114,584, U.K. Pat. No. 577,569, and Japan Pat. No. 63-9685 each discloses a rotary vane pump device featuring a stationary housing with an end closure structure installed at each axial end and with fluid transfer ports. Within said stationary housing a rotor is concentrically secured to a rotational shaft. Said rotational shaft is radially and axially constrained by rotational bearings installed in said end closure structure. Said rotor is fitted with an axially aligned radial vane slot at each of several centers uniformly distributed around its periphery. Each said rotor slot annularly constrains one radial vane but permits relative sliding motion in a radial direction. Said radial vane is radially constrained at each axial end by a rotating ring configured as an axially extended peripheral flange on a rotating disk. Said rotating ring is proportioned to maintain a constant distance between the outer peripheral edge of said radial vane and the bore of said stationary housing. Centripetal load induced by said radial vane due to rotor rotation is imposed on the said rotating ring by direct edge contact of said radial vane. Said rotating disk is radially and axially constrained by a low friction rotational bearing. The rotational axis of said rotating disk is aligned to be concentric with the longitudinal axis of the bore of said stationary housing. Said rotating disk
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