GB2125488A

GB2125488A - A variable speed device for a hydraulic turbine

Info

Publication number: GB2125488A
Application number: GB08223768A
Authority: GB
Inventors: David William Frost
Original assignee: Butterworth Systems Inc; Butterworth System Inc
Current assignee: Butterworth Systems Inc; Butterworth System Inc
Priority date: 1982-08-18
Filing date: 1982-08-18
Publication date: 1984-03-07

Abstract

It comprises a section 1 of the turbine liquid flow path in which a pivoted a vane 3 offset with respect to the central longitudinal axis of the section. The vane 3 can be locked in different positions, all at an angle to the longitudinal axis of flow of the turbine liquid. <IMAGE>

Description

SPECIFICATION A variable speed device This invention relates to a device for controlling the speed of turbines.

Turbines are often used to drive the mechanism for tank cleaning machines, e.g. machines for cleaning oil tanks on land or sea. It is often necessary to use more than one of these machines for cleaning a tank and however carefully designed these machines are, it is found that their speeds will vary slightly and this can cause problems. Accordingly it is highly desirable to have a simple mechanism which can be adjusted so that the speed of one or more of the machines can be altered slightly, usually by less than 10%. In this way the machines can be made to clean a tank so that they all have the same washing profile and speed of washing.

In accordance with this invention a variable speed device suitable for controlling the speed of a turbine comprises a section of the turbine liquid flow path in which is pivoted a vane offset with respect to the central longitudinal axis of the section, which vane can can be locked in different positions, all at an angle to the longitudinal axis of flow of the turbine liquid.

The section of the flow path housing the vane will be upstream of the turbine blades and usually this section will be of circular cross-section. In its simplest form the vane will be pivoted about a spindle, this spindle being traverse usually perpendicular, to the longtitudinal axis of the flow path.

The vane will usually be substantially rectangular in shape and should preferably be streamlined so that it presents a convex edge to the flow of liquid and tapers slightly towards the downstream edge. The vane has to be offset with respect to central longitudinal axis of the section and usually the vane is narrow enough so that it is located between this central axis and the inner wall of the section.

The vane can be locked in various ways but one simple way is for the shift about which the vane pivots to be extended so as to protrude outside the section of the flow path i.e, outside the flow pipe, so as to enter a collar having a grub screw, bolt or simple lock nut which can be tightened against the extended shaft. Usually the vane will be locked at an angle no greater than 1 5, from the longitudinal axis of the flow path of turbine liquid.

In a preferred ernbodiment there are four vanes pivoted in the section of the flow path, said section being of circular cross-section, one pair pivoting about one axis perpendicular to the axis of the flow of turbine liquid and other the pair pivoting about another axis perpendicular to the axis of the flow of turbine liquid. Preferably the two axis about which the pairs of vanes pivot are perpendicular to one another. Preferably these vanes are also streamlined so that the leading edge is convex and so that there is a taper towards the downstream edge. Preferably all the vanes are located between the central longitudinal axis and the inner wall of the section.

With this preferred embodiment it is possible to provide means for ensuring that all the four vanes are deflected from the axis of flow of the turbine liquid by substantially the same amount. This can be achieved by providing a ring rotatable within the circular pipe through which the turbine liquid flows, one end of each vane being attached to this ring so that rotation of the rotatable ring causes the vanes to deflect by equal amounts.

In order to lock the vanes a deflector rod control can be used. In this control which is housed outside the flow path section, a rod engages a slot formed in one end of the spindle about which one pair of vanes in pivoted. Rotation of this rod causes rotation of one set of vanes and hence through the rotatable ring the other set of vanes. The other end of this rod can be locked by a simple lock nut and hence the vanes are also locked in position.

This invention is now described with reference to the accompanying drawings in which: Figure 1 shows a perspective view of the simplest form of device according to this invention; Figure 2 shows an end elevation of the device shown in Fig. 1; Figure 3 shows a perspective view of a more sophisticated form of the device; and Figure 4 shows a cross-section through the centre of the device shown in Fig. 3.

Referring to Figs. 1 and 2 a section 1 of the turbine liquid flow path has a spindle 2 pivoted diametrically. Fixed to this spindle 2 is vane 3 which as can be seen is slightly streamlined. In Fig. 2 the vane 3 is shown in a different pivoted position to that shown in Fig. 1 but clearly shown is how the vane is offset with respect to the central longitudinal axis 30 of the section 1.

Although the spindle 2 is rotatable in its bearings, one of which is indicated at 4, nevertheless by virtue of one end of the spindle 2 passing through the wall section 1, the spindle 2 can be locked in position. This end of the spindle 2 extends into the collar 5 attached to the section 1, and terminates in a knob 6. The collar 5 is provided with a locking nut 7 and this when screwed tight bears against spindle 2, thereby preventing its rotation.

To operate the device of Fig. 1 and 2 one merely rotates the spindle 2 by means of the knob 6 until the desired inclination of the vane 3 is achieved and locks it in this position by tightening nut 7.

Referring now to Fig. 3 and 4 four vanes 11, 1 2 and 1 3 and 1 4 are housed in the cylindrical section 10 of the turbine liquid flow path and each are separately fixed to short axles 15, 16, 1 7 and 18, three of which are visible in Fig. 4. These axles all pivot about recesses in a central cylindrical block 19 and recesses in the cylindrical section 10, one of which is shown at 20 in Fig. 4.

Part of the section 10 of the turbine liquid flow path comprises a rotatable collar 25. This collar 25 has a shoulder which engages with an enlarged section of the outer casing of the flow path section 10 so that the collar cannot move in a direction along the longitudinal axis of the section 10. Protruding inwards from this collar are four symmetrically placed contact rollers, 21, 22, 23 and 24. These contact rollers engage with recesses in each of the vanes, one of which, 26, is shown in Fig. 4.

With this arrangement deflection of one vane causes rotation of the collar 25 within the outer casing of section 10 with similar deflections by the other three vanes, all the vanes deflecting in a clockwise or an anti-clockwise direction when they are viewed along the longitudinal axis of the section 10.

In order to be able to deflect the vanes and lock them in the desired position the device is provided with a deflector rod control, indicated generally at 27. Basically, this comprises a rod 28 whch keys into a slot provided at the end of spindle 16. This rod terminates in a knob 27 which can be rotated by hand. A lock nut 29 is used to lock the device in position once the blade dangle has been set.

Claims

CLAIMS:

1. A variable speed device suitable for controlling the speed of a turbine comprising a section of the turbine liquid flow path in which is pivoted a vane offset with respect to the central longitudinal axis of the section, which vane can be locked in different positions, all at an angle to the longitudinal axis of flow of the turbine liquid.

2. A device according to claim 1 wherein the vane is pivoted about a spindle, perpendicular to the longitudinal axis of the flow path.

3. A device according to claim 1 which comprises four vanes pivoted in a section of the flow path, said section being of circular cross-section, one pair pivoting about one axis perpendicular to the axis of the flow of turbine liquid and the other pair pivoting about another axis perpendicular to the axis of flow of turbine liquid.

4. A device according to claim 3 wherein said two axes are perpendicular to one another.

5. A device according to either of claims 3 and 4 which includes a deflector rod control wherein a rod engages a slot formed in one end of the spindle about which one pair of vanes is pivoted and wherein a lock nut engages said rod so that it can be locked in position.

6. A device according to any one of the preceding claims wherein the or each vane is substantially rectangular in shape and streamlined so that it can present a convex edge to the flow of liquid and so that it tapers towards the downstream edge.

7. A device according to any one of the preceding claims wherein each vane is narrow enough so that it is located between the central longitudinal axis and the inner wall of the section.

8. A deviced according to claim 1 substantially as hereinbefore described with reference to Fig. 1 and 2 of the drawings.

9. A device according to claim 1 substantially as hereinbefore described with reference to Figs. 3 and 4 of the drawings.