Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Plural rigidly related blade sets
Reexamination Certificate
2000-06-02
2001-11-06
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Plural rigidly related blade sets
C415S199400, C415S199600, C415S202000
Reexamination Certificate
active
06312220
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to air turbine motors. The invention has been particularly developed for use in a pneumatic starter motor and will be primarily described with reference to this application. The motor is however suitable for use in other applications where pneumatic motors are used due to the nature of the operating environment or otherwise.
BACKGROUND ART
Pneumatic starter motors are used for cranking internal combustion engines for starting purposes and are typically used for large engines and engines operating in environments where electric starting systems can be hazardous such as in mines.
Some known pneumatic starter motors have utilised a arrangement in which a flow of air generally parallel to the axis of rotation of a turbine wheel interacts with turbine elements to drive the wheel in rotation. In some other known pneumatic starter motors, air is directed radially with respect to the axis of rotation of a turbine wheel to interact with radially oriented elements which drive the wheel in rotation. Whilst both arrangements have been used to provide satisfactory air motors for pneumatic starters and other applications, improvements in output and operating characteristics are continuously sought.
DISCLOSURE OF THE INVENTION
It is an object of this invention to provide an improved air turbine motor.
Accordingly, this invention provides an air turbine motor including a turbine wheel mounted for rotation about an axis, a first set of elements displaced around said turbine wheel and arranged to drive said turbine wheel in rotation about said axis in a first direction in response to an axial flow of air generally parallel to said axis, a second set of elements displaced around said turbine and arranged to drive said turbine wheel in rotation about said axis in said first direction in response to a radial flow of air generally perpendicular to said axis, and means to direct drive air to said first set of elements in an axially directed flow and to direct drive air to said second set of elements in a radially directed flow.
In the preferred form of the invention, the drive air is firstly directed to the first or axially driven set of elements and is subsequently directed to the second or radially driven set of elements. Although this is the currently preferred configuration there are applications in which the path of the drive could be reversed.
Preferably, the axially driven set of elements is arranged around an outer circumferential edge of the turbine wheel and the radially driven set of elements is arranged on a face of said turbine wheel.
The radially driven set of elements are preferably arranged in two consecutive stages whereby the drive air passes through one stage and then the other stage. The consecutive stages are preferably formed by arranging the elements in two concentric circular arrays.
The turbine wheel is preferably mounted between two stator arrangements. The first of the stators directs drive air axially toward said axially driven elements whilst the second stator re-directs air emerging from said axially driven elements in a radial direction to said radially driven elements.
This preferred turbine stator configuration prevents a high side thrust loading on the turbine wheel. This is because the inlet air through the first stator exerts force which is opposite to the axial force developed by the air passing through the radially driven elements on the remote side of the turbine wheel. Additionally, the configuration allows a very compact and easily assembled air turbine motor to be produced.
The air turbine motor according to this invention has been found to provide a superior power output for a given drive air input. This allows a corresponding reduction in the size of the motor to produce a given power output. The air turbine motor of this invention also as a higher stall torque, that is, torque at zero rpm. This is particularly important for applications to pneumatic starter motors since start load is frequently very high.
The use of multiple stages through the respective axial and radial elements also allows speed control of the turbine motor.
The invention will now be described, by way of example only, with reference to the accompanying drawings.
REFERENCES:
patent: 4428715 (1984-01-01), Wiggins
patent: 4470256 (1984-09-01), Palmer
patent: 10945/23 A (1923-07-01), None
Derwent Abstract Accession No. G 3015C/32 SU 703670A (Leningrad Poly) Dec. 15, 1979—Abstract and Figure.
Derwent Abstract Accession No. 83-734030/32 SU 964197A (Lengd Kalinin Poly) Oct. 9, 1982—Abstract and Figure.
Derwent Abstract Accession No. 91-085835/12 SU 1560731A (Lengd Kalinin Poly) Apr. 30, 1990—Abstract and Figure.
Look Edward K.
Nguyen Ninh
Welsh & Katz Ltd.
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