US2851245A - Radial flow exhaust turbines for use with diesel engines - Google Patents

Description

E. s. 1.. BEALE 2,851,245

RADIAL FLOW EXHAUST TURBINES FOR USE wrm-x DIESEL mamas Sept. 9, 1958 2 Sheets-Sheet 1 Filed Feb. 11, 1953 Mam a -i /NVENTOR 4% ATTORNEYS Sept. 9, 1958 'E. s. BEALE 2,851,245

RADIAL FLOW EXHAUST TURBINES FOR USE WITH DIESEL ENGINES Filed Feb. 11, 1953 2 Sheets-Sheet 2 INVENTOR Z1 9, 1M WM m BY ///s ATTORNE).

'nited States RADIAL FLOW EXHAUST TURBINES FOR USE WITH DIESEL ENGINES Application February 11, 1953, Serial No. 336,417

6 Claims. (Cl. 253-40) The present invention relates to radial flow exhaust gas turbines for use with diesel engines and of the kind having axially projecting turbine blades carried on a rim which extends through an annular slot in one side of the turbine casing and is so constructed and arranged in relation to the margins of the annular slot that only small running clearances are left between the rim and the casing. The opposed surfaces between which these small running clearances are provided will be referred to hereafter for convenience as sealing surfaces. In known exhaust gas turbines, these sealing surfaces extend parallel to the axis of the rotor.

It has been found that the fouling consisting of oily soot which is deposited in the above-mentioned running clearances can be a serious source of trouble. For example, if the rotor and the turbine casing are both made of the same material, the fouling deposited in the outer running clearance, i. e. the clearance on the radially outer side of the rim, will substantially reduce the effective radial dimension of this clearance while the turbine is running. Consequently, when the turbine stops and cools down, the further reduction in this radial dimension resulting from the casing, owing to its higher working temperature, contracting more than the rotor, will cause the fouling to be tightly clamped between the sealing surfaces. The width in the axial direction of the fouling deposit in what was the running clearance is then too great to allow this deposit to be forced out laterally from between the sealing surfaces. The turbine will not therefore start up again when required, since the starting torque of the rotor is insuflicient to overcome the frictional engagement of the sealing surfaces through the fouling compressed between them.

Similarly, if, after the turbine has been running light for some time, a comparatively heavy load is suddenly applied to the turbine shaft, the casing will expand more than the rotor, thereby further reducing the inner running clearance, i. e. the clearance on the radially inner side of the rim, which has already been reduced to some extent by the fouling deposited in it. Consequently, this deposited fouling will give rise to a frictional braking or jamming effect between the rotor and the turbine casing, thereby reducing the output of the turbine at a time when a high output is most desirable.

The present invention has for its object to remove or obviate such difficulties.

According to the invention, this object is achieved by reducing the area of at least one of the running clearances, without at the same time interrupting the annular continuity of the corresponding sealing surfaces. The reduction in the area of the running clearance may conveniently be obtained by forming said clearance between a narrow sealing surface on the apex of a blunt continuous annular edge on said rim (or said casing) and an opposed sealing surface on said casing (or said rim), the arrangement being such that two enlarged annular clearance spaces are provided directly adjacent the two sides respectively of said annular edge for the reception of atent ice fouling residues removed from the running clearance by the interaction of the sealing surfaces.

The said running clearance is advantageously located between edges formed on two opposed continuous annular ridges formed respectively one on the rim of the rotor and the other on the turbine casing.

The width of the apex of the edge, or of each edge, may be between inch and inch and in any case is preferably not more than inch.

The rim may conveniently be formed with two continuous annular ridges having narrow cylindrical apex parts located opposite cylindrical surface parts of the casing on the two sides respectively of the annular slot.

The avoidance of the troubles referred to earlier in this specification can be still further ensured by disposing the sealing surfaces of at least one of the running clearances at a substantial angle to the axis of the rotor, mounting the rotor in the casing so as to have a limited amount of end float and so arranging said rotor in relation to the turbine casing that, when the turbine is running, it tends to assume a position in which the clearance between said sealing surfaces is a minimum, the rotor being nevertheless free to move away from this position, when required, to prevent any excessive reduction in the etfective working clearance due to the effects of the fouling deposited between the sealing surfaces, or to the differential expansion of the rotor assembly and the turbine casing, or to both of these causes. The substantial angle between running clearance and rotor is preferably but may be any smaller angle greater than about 45.

The invention is illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a view mainly in longitudinal section, but partly in elevation, illustrating a radial flow exhaust turbine according to one embodiment of the invention, and

Fig. 2 is a similar view illustrating a radial flow exhaust turbine according to another embodiment.

Referring to Figure l, the turbine casing which is indicated generally by reference 11 accommodates a turbine shaft 12 which is mounted in ball bearings, such as 13 fitted with oil seals such as 14. Keyed on one end of the shaft 12 and secured by means of a nut 15 is a rotor in: dicated generally by reference 16. The rotor 16, which is provided with radially projecting fan blades 17, also has a ring of axially projecting turbine blades 18 mounted on a rim 19 projecting through an annular slot in one side of the casing 11.

The turbine is driven by exhaust gases supplied to it from the exhaust box (not shown) of a diesel engine through a pipe 2% and the gases are discharged from it through an exhaust pipe 21 which communicates with the exhaust gas collector space 21.

In this embodiment, an outer working clearance between the rim 19 and the annular slot through which it projects is formed between an interior cut-away part of the turbine casing 11 at the mouth of the annular slot on the one hand and the outer surface of a radially projecting ridge 22 on the rim 19 on the other hand. The cut-away part includes a cylindrical surface 23, which is of larger diameter than the cylindrical interior surface 24 of the main outer part of the turbine casing wall, and an adjoining frusto-conical surface 25, which interconnects these two cylindrical surfaces 23 and 24. The outer surface of the ridge 22, which is ,4 inch wide, is directly opposite that portion of the cylindrical surface 23 which adjoins the frusto-conical surface 25. The ridge is bounded on the side towards the turbine blades 18 by a surface 26 normal to the rotor axis which adjoins at right angles the outer cylindrical surface of the ridge 22. The said outer cylindrical surface is of such a diameter as to have ample clearance within the surface 23. The ridge 22 is bounded on the other side by one side wall of a semi-circular section groove 27, the other side wall of which is located outside the mouth of the annular slot.

The inner working clearance in this case is formed between a plain cylindrical edge 28 of the casing 11 forming the inner boundary of the annular slot and a ridge 29, projecting radially inward from the rim of the rotor. The circumferential cylindrical surface of this ridge 29, which is the same width as the ridge 22 of the outer clearance, is situated directly opposite that part of the cylindrical edge surface 28 which is on the side towards which the turbine blades 18 project. Opposite the remainder of the cylindrical edge surface just referred to is part of an arcuate section annular groove 30 in the rotor rim 19, .one wall of which forms a flank of the ridge while its other wall is located outside the mouth of the annular slot. The annular slot hereinbefore referred to is the slot bounded by the surfaces 23, 25 on the one hand, and the surface 28 on the other hand.

The exhaust turbine illustrated in Fig. 2 is similar as regards its general form and arrangement to that illustrated in Fig. 1, and the main parts are indicated by the same references as the corresponding main parts in Fig. 1.

The rotor shaft 12 of the turbine in Figure 2 is, however, mounted so as to have a limited amount, e. g., inch, of end float and is spring-loaded by means of a spring 31 arranged between a thrust bearing 32, which is supported against a flange 33 on the shaft 12, and an abutment sleeve 34, which is supported against the outer race 35 of a combined journal and thrust bearing. The outer race 35 is located on the side remote from the abutment sleeve 34 by a flanged ring 36 secured to the casing 11 by means of bolts 37.

The inner race 38 of the combined journal and thrust bearing is mounted on areduced diameter part 12' of the shaft 12 and is located between a stop washer 39, which is supported against a shoulder40 on the shaft 12, and a sleeve 41 pinnedon a part 12" of the shaft 12 which is of still more reduced diameter.

The form of the outerrace 35 is such as to limit the axial movement of the shaft 12 under the action of the spring 31 to the right as seenin Fig.2, and movement of the shaft in the opposite directionis limited by the stop washer engaging the outer race 35.

In this embodiment, the portion of-the rim 19 entering the mouth of the annular slot in the casing 11 is cut away to provide substantial clearances betweenit and the walls of the slot, and the necessary sealing surfaces are located in parallel planes normal to the axis of the rotor shaft, instead of parallel to said axis as in Fig. 1.

The sealing surfaces on the rim 19 are formedon A; inch wide apex portions of annular ridges 42, 43, projecting axially towards the casing 11, while those in the casing 11 are similarly formed on annular ridges 44, 45 projecting axially from the casing towards the rotor. The flanks of all four ridges 42 to 45 are formed by walls of arcuate-section annular grooves, which provide adequate clearance spaces to receivefouling residues removed from between the sealing surfaces on the opposed ridges 42, 44 and 43, 45.

Fig. 2 shows-the rotor shaft, in the axial position which it occupies when there is substantially no fouling deposit between the sealing surfaces, and the clearance between these metallic surfaces has its minimum value. The pressure of the spring 31 is then supported by the combined journal and thrust bearing. Any substantial reduction in the working clearance between the sealing surfaces, due to fouling deposited between said surfaces or differential expansion between the rotor and shaft assembly 16, 12 and the casing 11 or both, is prevented by the provision for movement of the assembly 16, 12 to the left, as seen in Fig. 2, against the pressure of the spring 31, which movement is limited by the stop washer 39 engaging the outer race 35.

While it is generally desirable to reduce the areas of both the inner and outer running clearances between the rotor rim and the annular slot, as shown in the drawings, it may often be sufficient in particular cases to effect such a reduction at one of the two clearances only.

I claim:

1. A radial flow gas-turbine comprising a casing member, a rotor member mounted for rotation about an axis in said casing member and having a limited amount of end float, said casing member having an annular slot in one side thereof, a ring of axially-projecting turbine blades carried by said rotor member and extending from said rotor member through said annular slot, and sealing means between said rotor member and said casing member adjacent said annular slot, said sealing means providing a small running clearance and comprising an annular ridge on at least one of said members, a narrow sealing surface at the apex of said ridge, said sealing surface being disposed close to a cooperating sealing surface on the other said member, said sealing surfaces being at an angle exceeding 45 to said axis, said ridge and said casing being provided with enlarged clearance spaces therebetween on the sides of said ridge for the reception of fouling residues removed from the sealing surfaces by the relative movement of such surfaces, and means for exerting force between said casing and said rotor in a direction to urge said rotor axially towards its position of minimum clearance between said sealing surfaces but permitting axial movement of said rotor to increase the clearance when necessary due to the deposit of fouling residues on said sealing surfaces, said means comprising a spring.

2. A radial flow gas-turbine comprising a casing member, a rotor member mounted. for rotation about an axis in said casing member, an annular slot in one side of said casing member, a ring of axially projecting turbine blades carried by said rotor member and extending from said rotor member through said annular slot, and sealing means between said rotor member and said casing member located one adjacent the radially inner boundary and the other adjacent the radially outer boundary of said annular slot, each said sealing means providing a small running clearance and comprising an annular ridge on at least one of said members, a narrow sealing surface at the apex of said ridge, said sealing surface being disposed close to a cooperating sealing surface on other said member, and enlarged clearance spaces on either side of said ridge near the radially outer boundary of said annular slot for the reception of fouling residues removed from the sealing surfaces by the relative movement of such surfaces.

3. A radial flow gas turbine comprising a casing having an annular slot in one side thereof, a rotor mounted for rotation about an axis in said casing, said rotor comprising a rim extending through said annular slot, a ring of axially projecting turbine blades carried by said rim and disposed in said casing, and sealing means between said rim and said casing adjacent said annular slot and providing a small running clearance between said rim and the portion of said casing defining said annular slot, said sealing means comprising a single radially extending ridge, a narrow sealing surface at the apex of said ridge, a fouling residue receiving groove on one side of said ridge, a fouling residue receiving clearance space at the other side of said ridge, and a cylindrical surface having a cut-away portion constituting a sealing surface cooperating with said narrow sealing surface at the apex of said ridge, said cut-away portion constituting said sealing surface extending laterally on opposite sides of said ridge.

4. A radial flow gas turbine as claimed in claim 3, in which the width of said sealing surface at the apex of said ridge is between of an inch and Ma of an inch.

5. A radial flow gas turbine comprising a casing having an annular slot in oneside thereof, a rotor mounted for rotation about an axis in said casing, said rotor comprising a rim extending through said annular slot, a ring of axially projecting turbine'blades carried by said rim and disposed in said casing, and sealing means between said rim and said casing adjacent said annular slot and providing a small running clearance between said rim and the portion of said casing defining said annular slot, said sealing means comprising a single radially extending ridge on said rim, a narrow sealing surface at the apex of said ridge, a fouling residue receiving groove on one side of said ridge, a fouling residue receiving clearance space at the other side of said ridge, and said casing having a cut-away portion defining a wall of said annular slot and forming a cylindrical sealing surface cooperating with the apex of said ridge, said cylindrical surface extending laterally on opposite sides of said ridge.

6. A radial flow gas turbine comprising a casing member having an annular slot in one side thereof, a rotor member mounted for rotation about an axis in said casing, a ring of axially projecting turbine blades carried by said rotor member and extending from said rotor member through said annular slot, sealing means between said rotor member and said casing member adjacent said annular slot, said sealing means providing a small running clearance and comprising a single annular ridge on at least one of said members, a narrow sealing surface at the apex of said ridge, a cooperating sealing surface on the other said member disposed close to said narrow sealing surface at the apex of said ridge, said sealing surfaces being at an angle exceeding 45 to said axis, said ridge and said casing member being provided with enlarged clearance spaces therebetween and on opposite sides of said ridge for the reception of fouling residues removed from the sealing surfaces by the relative movement of such surfaces, and resilient means for exerting force between said casing and said rotor in a direction to urge said rotor axially towards its position of minimum clearance between said sealing surfaces but permitting axial movement of said rotor to increase said clearance when necessary due to the deposit of fouling residues on said sealing surfaces.

References Cited in the file of this patent UNITED STATES PATENTS

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