US2334625A - Turbomachine - Google Patents

Description

Nov. 16, 1943. F. A. M. HEPPNER TURBOMACHINE Filed July 15, 1942 frwanfir E Patented Nov. 16, 1943 2,334,625 TURBOMACHINE Fritz Albert Max Heppner, Leamlngton Spa, England, assignor to Armstrong Siddeley Limited, Coventry, England Motors Application July 15, 1942, Serial No. 451,015 In Great Britain March 26, 1941 4 Claims. (Cl. 230-132) This invention relates to rotary machines such as blowers or compressors and turbines.

In a high-speed rotary centrifugal blower or compressor, the rotor itself, which is usually of the straight, radially-bladed type with entry at both ends, is a highly eillcient element, but substantial losses are sustained in the diffuser which surrounds the rotor. A principal cause of these losses is friction of the fluid against the walls of the casing, and to reduce this, according to the main feature of the present invention, the casing is provided with rotating end walls. A convenient arrangement is to interconnect the peripheries of the two end walls with a small number of blades of thick streamline section with well rounded entry ends, thus forming a species of rotating cage. This is freely mounted on bearings and the blade form and angle designed with reference to the most suitable rotational speed of the cage.

Since the circumferential speed of the fluid is decreasing after it leaves the rotor, the rotating end walls could with advantage be staged-that is to say, divided into annular zones rotating at different angular speeds, if practical difficulties admit. In ordinary conditions two stages at the most would be suflicient. There would then be two cages one enclosing the other, their axial sections being such as to give a smooth walled passage of suitable section, and the second would be surrounded by a volute chamber of usual design. Suitable dimensions would be an outside diameter of the first cage about 40 per cent greater than that of the rotor, and of the second cage about 70 to 80 per cent greater.

In view of the high speeds which may come in question care in journalling is necessary, and for this purpose I prefer to use air bearings for locating the rotating cage or cages.

In the accompanying sheet of diagrammatic drawings:

Figure l isa fragmentary sectional elevation showing a centrifugal compressor with a single rotating cage according to the invention;

Figure 2 is a fragmentary cross-section taken on the line II--II of Figure l; and

Figure 3 indicates one method of rendering the bearing operative when starting up.

In the construction shown, ll represents the rotor shaft with straight, radially-disposed blades l2 adapted to pick up air or other fluid from both sides. I3 is the volute chamber.

In the present instance there is but a single rotating cage I4, built up of two or more parts, which is journalled in cylindrical portions l5 of the casing of the volute chamber through air bearings It, being endwise located by coacting side faces in conjunction with labyrinth packings IT. The shape and arrangement of the blades I8 is shown most clearly in Figure 2.

A blower or compressor constructed as described above may with advantage have its rotor constructed with interlaced staggered channels on opposite ends and with the outer edges of the blades in zigzag formation, as described in my U. S. application No. 364,291.

A blower 0r compressor in accordance with the present invention is well adapted for use as a supercharger for an internal combustion engine. It may then be driven by the engine instead of v by an exhaust turbine, though the latter drive -may be used if desired.

Another field of application is to internal-combustion turbines; in such case, since the energy circulating in the system is a multiple of the energy taken out, anyincrease in efliciency of the compressor will result in a multiple increase in the-overall efficiency. Such a compressor may be used in conventional form, that is to say, with stationary casing or diffuser member, or in a plant arranged as described in my U. S. application No. 364,291 wherein the secondary member rotates and is used to convey the output out of the plant.

It will be understood that the air bearing (the clearance of which is of the order of Mecca of an inch) is not operative at low speeds, and provision must be made for the journalling of the rotating cage when starting up. One such arrangement is diagrammatically portrayed in Figure 3, wherein the cylindrical portions l9, IQ of the cage are each supported through a pair of rollers 20, 20. Each of these rollers is pivotally mounted upon a lever 2|, the levers being lightly spring-pressed, as at 22, to bias the rollers into engagement with the cage. The free end of l. A rotary fluid pressure machine having a stationary casing, a rotor, a freely rotatable cage between said casing and rotor, said cage in operative position of the machine being spaced from frictional contact with the casing, motion 'erative position of the machine being spaced from frictional contact with the casing, supporting means adapted to space said cage in the inoperative position of the machine, and pneumatic means responsive tothe fluid pressure developed by the machine in operative position to remove said supporting means from contact with the cage, said supporting means comprising rollers adapted to move into and out of contact with said cage.

3. A rotary fluid pressure machine having a stationary casing, a rotor, a freely rotatable cage between said casing and rotor, said cage in operative position of the machine being spaced from frictional contact with the casing, motion permitting supporting means adapted to space said cage in the inoperative position of the machine, and pneumatic means responsive to the fluid pressure developed by the machine in operative position to remove said supporting means from contact with the cage, and means urging said supporting means into contact with said cage in the inoperative position of the. machine.

4. In combination with a fluid pressure machine having a stationary casing or rotor, and a freely rotatable cage between the casing and ro-' tor, of supporting means for spacing the cage from the casing when the machine is at rest, and pneumatic means in communication with said casing to cause withdrawal of the motion permitting supporting means when the fluid pressure in said casing reaches a speed suflicient to space the cage from the casing.

FRITZ ALBERT MAX HEPPNER.

Images