GB2397345A

GB2397345A - A Triple Gear Pump

Info

Publication number: GB2397345A
Application number: GB0301049A
Authority: GB
Inventors: Raymond Martin Johnson; Stephen James Walker
Original assignee: Dana Automotive Ltd
Current assignee: Dana Automotive Ltd
Priority date: 2003-01-17
Filing date: 2003-01-17
Publication date: 2004-07-21
Also published as: GB0301049D0

Abstract

A pump (10) including three gears (12, 14, 16) which mesh so that rotation of one gear (14) causes rotation of the other gears (12, 16), an inlet (36), an outlet (38) and a housing (17) provided with a pumping chamber in which the gears (12, 14, 16) are mounted for rotation about three generally parallel axes (X, Y, Z). The pumping chamber including first (A, D) and second (C, B) pairs of ports, one pair (A, D) being in fluid communication with the inlet (36) and the other pair being in fluid communication with the outlet (38), wherein the pumping chamber is substantially closed by means of a closure assembly (22). There is a passage (25) in a first side of the closure assembly (22) adjacent to the pumping chamber, the passage (25) forming a first fluid path between the ports (C, B) of the second pair, and two apertures (26, 26') each of which extend from one port (A, D) of the first pair to a second fluid path (28) which extends along a second side of the closure assembly (22) between the two apertures (26,26').

Description

Title: Pump

Description of Invention

The present invention relates to a pump, particularly, but not exclusively, to a gear pump including three gears (a triple gear pump) mounted in a pumping chamber, the gears meshing so that rotation of one gear causes rotation of the other gears.

Triple gear pumps are known in which four ports are provided in the pumping chamber, pumped fluid being drawn into the pumping chamber via a first pair of the ports and being expelled from the pumping chamber via a second pair of the ports, one of each pair of ports being arranged diametrically opposite the other with respect to a central gear.

The pump may be provided with two inlets and two outlets, in which case each port of the first pair of ports is connected to an inlet and each port of the second pair of ports is connected to an outlet. In some applications, however, it is required that the pump should have a single outlet and a single inlet, in which case conduits may be provided to connect the first pair of ports to the same inlet and the second pair of ports to the same outlet. Typically the provision of such conduits increases the size and complexity of manufacture, and hence cost, of such a pump.

According to a first aspect of the invention we provide a pump including three gears which mesh so that rotation of one gear causes rotation of the other gears, an inlet by means of which pumped fluid is drawn into the pump, an outlet by means of which pumped fluid expelled from the pump, and a housing provided with a pumping chamber in which the gears are mounted for rotation about three generally parallel axes, the pumping chamber including first and second pairs of ports, one pair being in fluid communication with the inlet and the other pair being in fluid communication with the outlet, wherein the pumping chamber is substantially closed by means of a closure assembly which is provided with a passage in a first side of the closure assembly adjacent to the pumping chamber, the passage forming a first fluid path between the ports of the first pair, and two apertures each of which extend from one port of the second pair to a second fluid path which extends along a second side of the closure assembly between the two apertures.

By virtue of the invention, two ports in the pumping chamber may be connected to a single inlet and two ports in the pumping chamber may be connected to a single outlet of the pump by relatively simple and compact construction. Thus the cost of manufacturing the pump may be minimised and a reduction in overall pump size may be achieved, which can be of particular importance when the pump is used in an automotive application, for example, where space in an engine compartment is at a premium.

Preferably the closure assembly is mounted on the housing such that first side of the closure assembly is generally perpendicular to the axes of rotation of the gears.

Preferably the apertures extend through the closure assembly generally parallel to axes of rotation of the gears.

Preferably, the pump comprises first, second and third gears arranged in a generally linear array, the first and third gears being arranged diametrically opposite to one another with respect to the second gear. In this case, preferably the two ports of each pair of ports are arranged diametrically opposite one another with respect to the second gear.

Further preferably, the second gear is connected to a motor such that operation of the motor causes rotation of the second gear, the first and third gears being idler gears, rotation of the second gear causing rotation of the first and third gears.

The second, power, gear is thus hydraulically balanced which assists in reducing the level of noise generated by the pump, and reduces wear on the gears and pump housing, thus increasing the life of the pump.

Preferably the inlet is connected to one of the first pair of ports by means of a conduit which extends through the housing generally normal to the axes of rotation of the gears. Further preferably, the outlet is connected to one port of the second pair of ports by means of a conduit which extends through the housing generally normal to the axes of rotation of the gears.

The inlet is preferably located at an opposite side of the housing to the outlet.

Exemplary embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings; FIGURE 1 is an illustration of a plan view of a pump according to the first aspect of the invention; FIGURE 2 is an illustration of a section through the pump of Figure 1 along line P. FIGURE 3 is an illustration of a section through the pump of Figure 2 along line Q. and FIGURE 4 is an illustration of an exploded view of a pump according to the invention.

Referring now to the figures, there is shown a pump 10 including a first gear 12, a second gear 14 and a third gear 16, the first 12 and third 16 gears being arranged diametrically opposite one another with respect to the second gear 14. The gears 12, 14, 16 are mounted on spindles 18 in a housing 17 for rotation about three generally parallel axes X, Y. and Z respectively, and the gears 12, 14, 16 mesh such that rotation of one of the gears 12, 14, 16 causes rotation of the other two gears 12, 14, 16 in the directions shown in the arrows in Figure 1.

The gears 12, 14, 16 each have a top 12a, 14a, 16a and bottom 12b, 14b, 16b surface which are generally normal to the axes of rotation X, Y. Z and sides which are generally parallel to the axes of rotation X, Y. Z from which the teeth extend. The gears are mounted in a pumping chamber within the housing 17 such that the housing 17 forms an enclosure around the bottom surfaces 12b, 14b, 16b and the sides ofthe gears 12, 14, 16. The chamber is shaped such that there is just sufficient clearance between the teeth of the gears 12, 14, 16 and the housing 17 to permit rotation of the gears 12, 14, 16 within the housing 17.

The pumping chamber includes four ports A, B. C, D, the first A being between the first 12 and second 14 gears where the teeth of these gears 12, 14 separate, the second B being between the first 12 and second 14 gears where the teeth of these gears 12, 14 mesh, the third C being between the second 14 and third 16 gears where the teeth of these gears 14, 16 start to mesh, and the fourth D being between the second 14 and third 16 gears where the teeth of these gears 14, 16 separate. At each port A, B. C, D there is a part circular recess in housing 17.

The second gear 14 is connected to a motor 19 by means of a drive shaft such that when the motor 19 is activated the second gear 14 rotates about its axis Y in the directions illustrated by the arrows in the Figures. The drive shaft 20 extends from the bottom surface 14b of the second gear 14, through an aperture in the housing 17 to the motor 19 which in this example is bolted to the housing 17.

A closure assembly 22 is mounted on the housing 17 substantially to close the chamber over the top surfaces 12a, 14a, 16aofthegears 12, 14, 16.

The closure assembly 22 in this example includes a main closure part 24 in which is provided a first generally straight groove 25 which extends diametrically across the second gear 14 on a first side 24a of the main closure part 24 from a position adjacent to which, during rotation of the gears 12, 14, 16, the teeth of the first 12 and second 14 gears start to mesh (port B), to second position adjacent to which, during rotation of the gears 12, 14, 16, the teeth of the second 14 and third 16 gears start to mesh (port C).

The main closure part 24 also includes and two apertures 26, 26' which extend through the main closure part 24 from the first side 24a of the main closure part 24 generally parallel to the axes of rotation X, Y. Z of the gears 12, 14, 16. The two apertures 26, 26' and are located diametrically opposite one another with respect to the second gear 14, the first groove 25 extending between the two apertures 26, 26'. The first aperture 26 being located adjacent a position where, during rotation of the gears 12, 14, 16, the teeth of the first 12 and second 14 gears start to separate (port A), and the second aperture 26' located adjacent a position where, during rotation of the gears 12, 14, 16, the teeth of the second 14 and third 16 gears start to separate (port D). The apertures 26, 26' extend to a second side 24b of the main closure part 24b, the second side 24b being opposite to the first side 24a of the main closure part 24, and are connected by means of a second groove 28 in the second side 24b of the main closure part 24.

An end part 30 is mounted on the second side 24b of the main closure part 24 to close the main closure part 24, such that the second groove 28 and end part 30 form a passage for flow of fluid between the two apertures 26, 26'.

In this example, a sealing plate 32 is sandwiched between the main closure part 24 and the housing 17, the sealing plate 32 being provided with four generally circular apertures arranged in array corresponding to four corners of a square such that when the sealing plate 32 is in place, two of the apertures in the sealing plate are aligned with the two apertures 26, 26'in the main closure part 24, and the remaining two apertures in the sealing plate are aligned with the two ends of the first groove 25 in the main closure part 24. Thus the first groove 25 and the sealing plate 32 form a passage for flow of fluid from one end of the first groove 25 to the other.

The end part 30, main closure part 24, and sealing plate 32 in this example are all bolted to the housing 17 by means of four bolts 34 which each extend from the end part 30 through the main closure part 24 and sealing plate 32 to the housing 17. O-rings 25 are provided between the end part 30 and the main closure part 24, the main closure part 24 and the sealing plate 32, and the sealing plate 32 and the housing 17.

An inlet 36 and outlet 38 are provided in the housing 17, each extending from the pumping chamber through the housing 17 in a direction generally normal to the axes of rotation X, Y. Z of the gears 12, 14, 16 in a generally lO opposite direction to the other. The inlet 36 provides fluid flow path between port A to the exterior of the housing 17, and the outlet 38 provides a fluid flow path between port B to the exterior of the housing. The inlet 36 is connected to a source of fluid to be pumped, and the outlet 38 to a load requiring pumped fluid.

The pump 10 operates as follows.

Activation of the motor causes the second gear 14 to rotate in an anticlockwise direction when viewing the top surface 14a of the gear 14. By virtue of the meshing of the gears 12, 14, 16, this causes the first 12 and third 16 gears to rotate in a clockwise direction when viewing the top surfaces 12a, 16a of the gears 12, 16.

As the teeth of the gears 12, 14, 16 mesh, fluid in the manifold 22 is drawn through the inlet 36 into port A. A first portion of the pumped fluid is compressed between the teeth of the second gear 14 and a portion of the chamber wall 17a, which extends between port A and port C. Thus the first portion of fluid is transported to port C, pressurized, is forced along the first groove 25 from port C to port B and is ejected from the pumping chamber through the outlet 38. A second portion of the pumped fluid is compressed between the teeth of the first gear 12 and a portion of the chamber wall 17b which extends between port A and port B. Thus, this fluid is transported to port B. pressurized, and is ejected through the outlet 38.

A third portion of the pumped fluid is drawn along the first aperture 26 in the main closure part 24, along the second groove 28 and down through the second aperture 26' in the main closure part 24 to port D. A portion of this fluid is then compressed between the teeth of the second gear 14 and a portion of the pumping chamber wall 17c between port D and port B. This fluid is thus transported to port B. pressurised and ejected through the outlet. The remainder of the third portion of fluid is compressed between the teeth of the third gear 16 and a portion of the pumping chamber wall 17d between port D and port C. This fluid is thus transported to port C, pressurized, is forced along the first groove 25 from port C to port B. and ejected through the outlet 38.

By virtue of the provision of utilising the four ports A, B. C, D the output of pumped fluid and hence the pumping efficiency may be improved, whilst by virtue of the provision of grooves 25, 28 and apertures 26, 26' in the main closure part 24, the four ports A, B. C, D may be connected to a single inlet 36 and a single outlet 38 without the need to provide a complex arrangement of conduits in the pump housing 17.

In addition, as the fours ports are arranged in a symmetrical array around the second, power, gear 14, the gears 12, 14, 16 are hydraulically balanced, and thus the noise produced by the pump and wear of the gears 12, 14, 16 and housing are reduced, and hence the pump life is increased.

The above embodiment is described by way of example only, and various modification may be made to a pump within the scope of the invention.

For example, the two apertures 26, 26' in the end part need not be connected by means of a groove 28 in the main closure part 24. They may instead be connected by means of a groove or plenum in the end part 30 or any other passage in either the end part 30 or the main closure part 24.

There need not be a sealing plate 32 between the main closure part 24 and the housing 17, providing the main closure part 24 is located sufficiently close to the gears 12, 14, 16 to prevent significant leakage of fluid between the main closure part 24 and the top surface 12a, 14a, 16a of the gears 12, 14, 16.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A pump including three gears which mesh so that rotation of one gear causes rotation of the other gears, an inlet by means of which pumped fluid is drawn into the pump, an outlet by means of which pumped fluid expelled from the pump, and a housing provided with a pumping chamber in which the gears are mounted for rotation about three generally parallel axes, the pumping chamber including first and second pairs of ports, one pair being in fluid communication with the inlet and the other pair being in fluid communication with the outlet, wherein the pumping chamber is substantially closed by means of a closure assembly which is provided with a passage in a first side of the closure assembly adjacent to the pumping chamber, the passage forming a first fluid path between the ports of the first pair, and two apertures each of which extend from one port of the second pair to a second fluid path which extends along a second side of the closure assembly between the two apertures.

2. A pump according to claim 1 wherein the closure assembly is mounted on the housing such that first side of the closure assembly is generally perpendicular to the axes of rotation of the gears.

3. A pump according to claim 1 or 2 wherein the apertures extend through the closure assembly generally parallel to axes of rotation of the gears.

4. A pump according to any preceding claim wherein the pump comprises first, second and third gears arranged in a generally linear array, the first and third gears being arranged diametrically opposite to one another with respect to the second gear.

5. A pump according to claim 4 wherein the two ports of each pair of ports are arranged diametrically opposite one another with respect to the second gear.

6. A pump according to any preceding claim wherein the second gear is connected to a motor such that operation of the motor causes rotation of the second gear, the first and third gears being idler gears, rotation of the second gear causing rotation of the first and third gears.

7. A pump according to any preceding claim wherein the inlet is connected to one of the first pair of ports by means of a conduit which extends through the housing generally normal to the axes of rotation of the gears.

8. A pump according to any preceding claim wherein the outlet is connected to one port of the second pair of ports by means of a conduit which extends through the housing generally normal to the axes of rotation of the gears.

9. A pump according to any preceding claim wherein the inlet is located at an opposite side of the housing to the outlet.

10. A pump substantially as hereinbefore described with reference to and/or as shown in the accompanying drawing.

11. Any novel feature or novel combination of features hereinbefore described with reference to and as shown in the accompanying drawings.