GB2260788A

GB2260788A - Pump impeller

Info

Publication number: GB2260788A
Application number: GB9121216A
Authority: GB
Inventors: Malcolm James Clough
Original assignee: Jaguar Cars Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 1991-10-05
Filing date: 1991-10-05
Publication date: 1993-04-28
Also published as: GB9121216D0

Abstract

An impeller has a base plate 11 arranged to be mounted on a drive shaft for rotation therewith, a pressed metal corrugated annular element 16 and a metal annular shroud element 20; the base plate 11, corrugated element 16 and a shroud element 20 being secured together coaxially of one another with the corrugated element 16 sandwiched between the base element 11 and the shroud element 20, to define a plurality of radially extending passageways (23, Fig. 1). <IMAGE>

Description

UP IMPELLERS The present invention relates to pump impellers and in particular to impellers for the water pimps of motor vehicles.

A typical water pump for a motor vehicle includes an impeller mounted for rotation on a drive shaft. The impeller comprises a base plate mounted for rotation in a plane perpendicular to the axis of rotation of the drive shaft. The base plate has a series of radially extending flat or curved vanes. Water is introduced through an inlet to the centre of the impeller and is driven outwardly along the vanes and out through an outlet from the pump.

In order to improve the efficiency of the pump it Iias been found beneficial to close the channels between the vanes by means of an annular shroud, the shroud being secured coaxially of tulle base plate to the free edges of the vanes, so that the vanes defile a series of radially extending open ended passageways between the base plate and shroud. The annular shroud leaves the central portion of the impeller open, so that water entering the pump can enter the passageways and exit through tI)C open ends at the outer edge of the impeller.

With larger pumps, shrouded impellers of the typo.

described above may be cast from metal. However, hitherto with smaller impellers required for motor vehicle water pumps, the impellers have been moulded from plastics materials. In order to obtain adequate strength, the sections of the base plate, shroud and vanes must be relatively thick. As a result, the cross section of the passageways formed between the vanes is reduced with corresponding reduction in the pumping efficiency, for a given overall impeller size.

According to one aspect of the present invention aIl impeller comprises a base plate which is adapted to be mounted on a drive shaft for rotation therewith, a pressed metal corrugated annular element and a pressed metal annular shroud element; the base p]ate, corrugatecl element and shroud element being secured together coaxially of one another with the corrugated element sandwiched between the base element and tho shroud element, to define a plurality of radially extending passageways.

The base plate will preferably have a central boss hy means of which it may be secured to the drive shaft. The boss may be formed and the base plate shaped to its required configuration by pressing from sheet material or the base plate may be fabricated from sheet material, the boss being secured thereto in suitable manner.

The impeller in accordance with the present invention may consequently be manufactured from sleet material, fnt example, steel, each element being proiicocll Thy i relatively simple and inexpensive process and being be secured together in suitable manner, for example we]d in, brazing or bonding by means of an adhesive.

As the elements of the impeller are made from sheet metal, these may be thin in comparison with the plastic impellers produced hitherto so that the cross section areas of the passageways formed between the elements, will be increased relative to a plastic impeller of comparable size, thereby increasing the pumping capacity of the impeller.

The invention is now described, by way of example only, with reference to tie accompanying drawings in which: Figure 1 shows a section of an impeller formed in accordance w.ith the present invention; Figure 2 is an exploded isometric view oE the impeller illustrated in Figure 1; and Figure 3 shows an alternative form of corrugated annular element that may be used in the impeller illustrated in Figures 1 and 2.

As illustrated in Figures 1 and 2 a pump impeller 10 comprises a base plate 11. having a central boss 12 by which it is secured to a drive shaft 13. The base rlate 11 is contoured, having a raised central portion 14 surrounding the boss 12 with a concave curve to a flat portion 15 adjacent its outer periphery. A corrugated annular element 16 is secured to the base plate 11 coaxially thereof, the lower crowns 17 of the corrugations 18 lying flat against the base plate 11 and being secured thereto.

The depth of the corrugations 18 reduce towards the outer periphery of the corrugated element, so that the upper crowns 19 lie in a conical plane. An annular shroud element 20 having a conical outer peripheral portion 21 corresponding to the upper crowns 19 of the corrugated element 16, is secured to the upper crowns 19 so that it is coaxial with the base plate 11 and corrugated element 16. The inner peripheral portion 22 of the shroud element 20 provides an axially extending tubular formation.

The corrugations 18 of the corrugated element 16 thereby form a series of open ended passageways 23 between the base plate 11 and shroud element 20, the axially extending portions 24 of the corrugations providing radially extending vanes.

As illustrated in Figure 1, the impeller is located in a pump housing 25 which defines an axia] inlet chamber 2 and an annular outlet chamber 27. Fluid is delivered to the inlet chamber 26 and from there to the centlre of ti)C impeller 10 through the central aperture in the shroud element 20.The fluid enters the passageways 23, the curvature between the central portion 14 and outer portion 15 of the base plate 11 assisting in the change of direction of flow of the fluid, and the fluid is forced to the outer ends of the passageways 23 and the outlet chamber 27. The tubular formation provided by the inner periphery 22 of shroud element 20, is a close diametrical clearance with the wall of inlet chamber 26 and controls leakage of fluid back from the outlet chamber 27.

The base plate 11, annular corrugated element 16 and shroud element 20 are formed from sheet steel by pressing. The components are secured together in suitable manner, for example welding, brazing or bonding with an adhesive.

in the above embodiments the passageways 23 defined between the base plate 11 and shroud element 20 are directed radially. In order to enhance flow of fluid through the passageways, it is desirable that the inner ends of the passageways lead their outer ends relative to the direction of rotation of the impeller. This may be achieved by the use of an annular corrugated element 30 of the form illustrated in Figure 3, in which the axially extending walls 31 of the corrugations 32 are disposed spirally.

Claims

1. An impeller comprising a base plate which is .ClR5tef to be mounted on a drive shaft for rotation therewith, a pressed metal corrugated annular element arid a pressed metal annular shroud element; the base plate, corru(Wnted element and shroud element being secured together coaxially of one another with the corrugated element sandwiched between the base element and the shroud element, to define a plurality of radially exKtendiIlrJ passageways.

2. An impeller according to Claim 1 in which the base plate is provided with a central boss by means of which it may be secured to the drive shaft.

3. An impeller according to Claims 1 or 2 in which the base plate is contoured having a raised central portion with a concave curve to a flat outer peripheral portion.

4. An impeller according to Claim 2 or 3 in which the base plate with central boss is pressed from sheet metal.

5. An impeller according to Claim 2 or 3 in which the base plate is pressed from sheet metal, the central boss being secured thereto in suitable manner.

6. An impeller according to any one of ti preceding claims in which the crowns on one side of the corrugated annular element are shaped to lie flat against the outer periphery of the base plate while the crowns on the other side of the corrugated annular element are shaped to lie flat against the outer periphery of the s)iroucl elomellt. -

7. An impeller according to Claim 6 in which said crowns at the other side of the annular corrugated element lie in a conical plane, the outer periphery oE the annular shroud element being of corresponding conical configuration.

8. An impeller according to any one of the precediIlg claims in which an axially extending tubular formation is formed at the inner periphery of the shroud element, the tubular formation being a close tolerance clearance with a wall of an inlet chamber of an associated housing, the tubular formation providing a seal between the inlet chamber and an outlet chamber.

9. An impeller as claimed in any one of the preceding claims in which the inner ends of the radially extending passageways lead the outer ends thereof, relative to the direction of rotation of the impeller.

10. An impeller substantially as described herein, with reference to and as shown in Figures 1 to 3 of the accompanying drawings.