Pumps – Motor driven – Motor rotor intermediate coaxial pump rotors
Reexamination Certificate
2000-06-20
2002-05-21
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Motor rotor intermediate coaxial pump rotors
C417S251000, C417S366000, C417S369000, C417S360000, C417S361000, C417S372000
Reexamination Certificate
active
06390789
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a turbocompressor.
A turbocompressor is known which comprises a radial turbocompressor and an electric motor, with each of these units being arranged in a separate housing and with the shaft of the electric motor being coupled to the shaft of the radial turbocompressor via a flexible shaft part.
Disadvantageous in this known turbocompressor is the fact that the latter is designed to be rather large, that a plurality of seals and bearings is required and that the manufacturing costs of the turbocompressor are therefore relatively high.
The document DE 27 29 486 C1 discloses in
FIG. 1
a
a turbocompressor which includes two two-stage radial turbocompressors and also an electric motor, with these being coupled to a rigid shaft which is journalled at three positions with magnetic radial bearings. This embodiment has the disadvantage that the assembly is very complicated and difficult, that this arrangement is suitable for an at most two-stage radial turbocompressor and that the turbocompressor has relatively high dissipation losses.
SUMMARY OF THE INVENTION
It is an object of the present invention to propose an economically more advantageous turbocompressor.
This object is attained with a turbocompressor comprising an electric motor, a multistage radial turbocompressor and also a common shaft, with a part section of the shaft being formed as the armature of the electric motor and wherein a further part section of the shaft is formed as the rotor of the radial turbocompressor, with the rotor including a compressor shaft and also compressor wheels connected therewith, wherein a plurality of magnetic radial bearings are arranged spaced apart in the direction of extent of the shaft for the journalling of the shaft, wherein a single electromagnetic radial bearing is arranged between the armature of the electric motor and the compressor wheel, and wherein the electric motor, the radial turbocompressor, the shaft and also the radial bearings are arranged in a common housing sealed in gas-tight manner relative to the outside. The housing consists of a plurality of part housings which can be fixedly connected together, the electric motor is arranged in one part housing and the radial turbocompressor in one part housing and the armature of the electric motor and also the rotor of the radial turbocompressor are connectable to form a common shaft via a coupling arranged between the armature of the electric motor and the compressor wheel.
The object is furthermore satisfied in particular by a turbocompressor comprising an electric motor, a multiple-stage radial turbocompressor and a common shaft, with a partial section of the shaft being designed as the armature of the electric motor, and with a further partial section of the shaft being designed as the rotor of the radial turbocompressor, with the latter rotor comprising a compressor shaft and compressor wheels or impellers which are connected thereto, and with a plurality of electromagnetic radial bearings being arranged with spacing in the longitudinal direction of the shaft, with the radial bearings being supported on a common base element.
The object is further satisfied by a turbocompressor comprising a housing which is gas-tight towards the outside and within which an electric motor and also a multistage radial turbocompressor are arranged on a common shaft, wherein, for the journalling of the shaft, electromagnetic radial bearings are arranged spaced apart in its direction of extent and wherein a dry gas seal surrounding the shaft is provided between the electric motor and the radial turbocompressor in order to seal off the electric motor relative to the radial turbocompressor, with the electric motor having an inner space which is connected in fluid-conducting manner with an outlet opening which passes through the housing.
FIG. 1
shows a known turbocompressor which comprises an electric motor which is journalled at both ends and a radial turbocompressor which is journalled at both ends, with the shaft of the electric motor being coupled via a flexible shaft part to the shaft of the radial turbocompressor.
An advantage of the turbocompressor mi accordance with the invention is to be seen in that for the complete journalling of the entire shaft, in comparison with the exemplary embodiment in accordance with
FIG. 1
, three radial bearings, preferably designed as electromagnetic radial bearings, suffice in that a single radial bearing is arranged between the electric motor and the compressor. The turbocompressor can thus be manufactured economically.
The entire shaft can be designed as a single piece. In an advantageous embodiment the shaft of the electric motor as well as the shaft of the radial turbocompressor are connected via a coupling, in particular a coupling with as high a stiffness as possible. A very stiff coupling permits the design of a total shaft which has a largely homogeneous stiffness in the longitudinal direction of the shaft. The entire shaft or, respectively, the entire rotatable components of the turbocompressor behave thereby like a compact shaft, which has a positive effect on a stable running behavior of the turbocompressor. In addition this enables the entire shaft to be journalled in the axial direction with the help of a single axial bearing. In the embodiment known from
FIG. 1
a separate axial bearing each is required for the electric motor and the radial turbocompressor.
If a radial turbocompressor is arranged only at one side of the electric motor, then three radial bearings which are arranged to be spaced in the longitudinal direction of the shaft suffice for the complete journalling of the entire shaft. If a radial turbocompressor is, arranged at each side of the electric motor, then four electromagnetic radial bearings which are arranged to be spaced in the longitudinal direction of the shaft suffice for the complete journalling of the entire shaft.
Dispensing with a radial bearing between the electric motor and the radial turbocompressor has in addition the advantage that the entire shaft can be shorter, which is rotor-dynamically advantageous, enables the forming of a lighter shaft, and yields a more compact construction of the turbocompressor in addition. In this it should be considered that electromagnetic radial bearings have a substantially lower bearing load in comparison with hydrodynamic radial bearings, which results in a more advantageous dynamic behavior of the rotor because of the shorter shaft as well as the lower weight, which are of decisive importance in order to operate the turbocompressor reliably and without disturbance by means of electromagnetic bearings. This aspect is in particular of importance for radial turbocompressors which compress a fluid to a high pressure of for example 600 bar. When such a highly compressed fluid encounters a flow disturbance, relatively large radial and axial forces are generated which can be absorbed by the electromagnetic bearing, which has only a limited load capacity, only when the dynamic behavior of the rotor of the entire system is optimized.
In a particularly advantageous embodiment the motor and the radial turbocompressor are arranged in a common, hermetically sealed-off housing, in particular in a pressure housing, with a fluid-conducting input and output line passing through the housing or being fanged onto the housing in order to conduct in and out the fluid to be compressed. This arrangement has the decisive advantage that no seals against the outside, in particular against the atmosphere, are required at the shaft, which in addition to the cost advantage yields the further advantages that periods of disuse which are caused by sealing problems no longer arise, and that the total length of the shaft can additionally be reduced, which again increases the total weight of the shaft and the stability of the shaft which is held by electromagnetic bearings.
The radial turbocompressor with a pressure housing which is hermetically sealed off against the outside also permits the motor-compresso
Dessibourg Dominique
Grob Denis
Pradetto Jean Claude
Freay Charles G.
Solak Timothy P.
Sulzer Turbo AG
Townsend and Townsend / and Crew LLP
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