WO2010115667A1

WO2010115667A1 - Dual flow impeller and pump having the same

Info

Publication number: WO2010115667A1
Application number: PCT/EP2010/052739
Authority: WO
Inventors: Mavinkal Jayaram
Original assignee: Schaeffler Technologies Gmbh & Co. Kg
Priority date: 2009-04-07
Filing date: 2010-03-04
Publication date: 2010-10-14

Abstract

The invention is to a dual flow pump and a dual-flow impeller which is temperature sensitive and transfers the pump from low-flow to high-flow modes. A bi-metallic disk (16) is employed to engage a secondary impeller (14) and increase the pumping rate of the pump.

Description

Title

DUAL FLOW IMPELLER AND PUMP HAVING THE SAME

Field of the invention

This invention relates to pumps, and more particularly, to pumps having dual flow characteristics, i.e. a high-flow and a low-flow rate, which is dependent upon the temperature of the fluid being pumped. This invention also relates to the impeller design for a dual-flow pump, which is temperature dependent.

Background of the invention

Temperature dependent dual-flow pumps are known and generally have coupling mechanisms for coupling and de-coupling the impellers to move between a low- flow rate and a high-flow rate. Also, two-stage motors are employed for transferring between the low-flow rate and the high-flow rate based on the temperature of the fluid. Such motors generally employ a temperature sensor for the transition of the speed of the motor. Also, two-speed external gear reduction mechanisms between the motor and the pump are employed that shift the speed at which the pump operates based on the temperature of the fluid being pumped.

All of these various designs employ multiple mechanical components to achieve a dual-flow rate based on temperature. Sensors are generally employed to detect the change in temperature and switch the pump between the two flow rates.

Object of the invention

One of the objects of the present invention is to design a temperature dependent dual flow pump which employs minimal mechanical components. It is another object of the invention to minimize the maintenance necessary for the dual flow temperature dependent pump and to reduce the number of contaminants that are introduced into the fluid flow based on the workings of the pump. These and other objects of the present invention will more readily understood by reference to the following description.

Summary of the invention

The objects of the present invention are achieved by using a bi-metallic disk to effect a change in the flow rate of the pump. By employing a bi-metallic disk which is susceptible to temperature, the pump transfers between a low-flow rate and a high-flow rate. More specifically, the pump of the invention employs a dual flow impeller that contains only three parts, a low-flow impeller, a high-flow impeller, and a bi-metallic disk which, based on temperature changes, moves the high-flow impeller into and out of engagement so as to transfer the pump from a low-flow rate to a high-flow rate and from a high-flow rate to a low-flow rate as the temperature in the fluid changes.

Broadly, the dual-flow impeller of the invention can be defined as comprising: a first impeller having a first disk, first blades fixed at one end to a circumferential edge of the first disk and extending axially from the first disk, a ring fixed to the other end of the first blades and axially spaced form the first disk, and slots in the first disk aligned with a chord of the first disk; a second impeller having a second disk concentric with the first disk and axially movable in relation to the first disk, second blades fixed at one end to the second disk and extending axially from the second disk, one of each of the second blades aligned with one of each of the slots and the second blades axially movable through the slots; and a bi-metallic disk concentric with the first and second disk, the bi-metallic disk axially movable between the first disk and the ring, the bi-metallic disk having a center opening for fluid flow, the bi-metallic disk fixed to the second impeller such that when the bi-metallic disk axially moves from the first disk to the ring, the second blades axially move through the slots.

The first impeller is the low-flow impeller while the second impeller is the high-flow impeller. Bi-metallic disks are conventional and employ two different metals. The difference in the metals cause a change in the shape of the bi-metallic disk, thereby transferring a temperature change of the bi-metallic disk into a physical change of the shape of the bi-metallic disk. The pump of the invention employs the change in shape of the bi-metallic disk in order to effect the axial movement of the second impeller and change the dual flow impeller from low-flow to high-flow.

Preferably, the bi-metallic disk has slots on its outer circumferential edge which are aligned and mate to the blades of the first impeller. This keeps the bi-metallic disk radially stationary in the dual flow impeller while allowing the bi-metallic disk to move axially within the first impeller.

It is also preferred that the blades of the second impeller have tabs, which are aligned with and extend through the slots of the first impeller. These tabs are used to affix the bi-metallic disk to the second blades. This provides the axial movement of the second impeller.

Preferably, the inner circumferential edge of the bi-metallic disk has tabs which are bent towards the first disk so as to space the bi-metallic disk from the first disk. The length of the tabs do effect the distance that the second impeller is moved in an axial direction.

Preferably, a spring, such as a belville spring, is affixed to the back of the second impeller and is also affixed to the shaft of the pump. The spring acts as a return spring for the second impeller when the temperature of the fluid that is being pumped drops below a specific temperature and the bi-metallic disk snaps from the high-temperature shape to the low-temperature shape.

The pump of the invention provides dual flow rates for fluid based on temperature by using the dual flow impeller of the invention mounted in a housing which has an inlet and an outlet. A shaft extends into the housing and is used for mounting the impeller thereon.

These and other aspects of the invention may be more fully understood by reference to the following drawings which are used for purposes of illustration. Brief description of the Drawings

Fig. 1 illustrates the dual flow impeller of the invention;

Fig. 2 illustrates the first impeller (low-flow impeller);

Fig. 3 illustrates the second impeller (the high -flow impeller);

Figs. 4A-4D illustrate the bi-metallic disk of the invention;

Figs. 5-8 illustrate the operation of the disk and pump of the invention.

Detailed description of the Drawings

Fig. 1 illustrates dual flow impeller 10 having first impeller (low-flow impeller) 12, second impeller (high-flow impeller) 14 and bi-metallic disk 16 as a single unit wherein first impeller 12, second impeller 14 and bi-metallic disk 16 are concentric and aligned with axis 18. Second impeller 14 is moved axially by bi-metallic disk 16 to achieve low- or high-flow rates. Fig. 1 illustrates bi-metallic disk 16 in a cold position wherein second impeller 14 is not engaged and dual flow impeller 10 is in a low-flow mode.

Figs. 2-4 provide detailed description of the three components of dual flow impeller 10.

Turning to Fig. 2, first impeller 12 is made up of first disk 20 with circumferential edge 22. First blades 24 extend axially from first disk 20 having one end fixed to first disk 20 and the other axial end of first blade 24 fixed to ring 26. Opening 25 is defined by the surfaces of disk 20, blades 24, and ring 26. The length of blade 24 and the size of opening 25 define the volume of fluid pumped through opening 25. Opening 25 acts as an outlet for dual flow impeller 10. Collar 27 is used to fix dual flow impeller 10 to the shaft of the pump. Slots 28 have been formed in first disk 20. Slots 28 are aligned with chord 29 of disk 20. Collar 27 is press-fitted onto an existing pump shaft (not shown). It is used to fix the first impeller 12 rigidly to the pump shaft. It will be recognized that ring 26 provided rigidity and stability to blades 24. Ring 26 also acts as a stopper for the movement of bi-metallic disk 16 and second impeller 14.

Fig. 3 illustrates second impeller 14 having second disk 30 with circumferential edge 32. As illustrated in Fig. 1 , first disk 20 and second disk 30 share the same diameter and are concentric with each other on axis 18. Second blades 34 are fixed to second disk 30 and extend axially from second disk 30. Second blades 34 have tabs 36 which are used to fix bi-metallic disk 16 to second impeller 14 as illustrated in Fig. 1. Second disk 30 has center opening 37 for the shaft of the pump. It will be recognized that opening 37 is slightly larger than the internal diameter of collar 37 so as to allow second impeller 14 to move axially on the shaft of the pump. Blades 34 are aligned with chord 39 of second disk 30. Blades 34, as illustrated in Fig. 1 , are also aligned with slot 28 such that second impeller 14 can axially move, thereby allowing blades 34 to move through slot 28. Fig. 3 illustrates tabs 36 before they are bent, whereas Fig. 1 illustrates tabs 36 after they are bent so as to capture bi-metallic disk 16. Tabs 36 are bent over during the assembly of the dual flow impeller 10. Tabs 36 extending into slots 28, as illustrated in Fig. 1 hold second impeller 14 in an angularly rigid manner in dual flow impeller 10 and maintain the alignment of second blades 34 with slots 28 when dual flow impeller 10 is in the low-flow mode as illustrated in Fig. 1 .

Figs. 4A-4D illustrate bi-metallic disk 16. Bi-metallic disk 16 has bi-metallic ring 40 with an outer circumferential edge 42 which has slots 44 therein. Inner circumferential edge 46 defines opening 48. Tabs 49 are bent axially from inner circumferential edge 46. Fig. 4A is a top view of bi-metallic disk 16, while Fig. 4B is a bottom view of bi-metallic disk 16. Fig. 4C illustrates an enlarged view of the edge of bi-metallic disk 16, illustrating the concave nature of surface 47. Figure 4D illustrates both the concave nature of bi-metallic disk 16 as well as the axial reach of tabs 49. Bi-metallic disks are conventional and are known for their mechanical movement based on changes in temperature. Bi-metallic disks are often made of copper and steel or steel and brass due to the different temperature nature of steel, brass and copper. Bi-metallic disk 16 is manufactured such that the disk has a natural conical shape. On heating the disk, due to the temperature change in the fluid passing over the disk, the temperature reaches a critical or snap temperature for bi-metallic disk 16. At the point of temperature change, the conical nature of bimetallic disk 16 changes from convex to concave which will be illustrated in more detail in Figs. 5-8. This physical change in the shape of bi-metallic disk 16 is reversible upon the cooling of the disk. Since the fluid that flows through the pump is in direct contact with bi-metallic disk 16, the temperature of the fluid that runs through the pump effects the temperature of bi-metallic disk 16. In designing the pump, the temperature at which the pump converts from low-flow mode to high- flow mode is dependent upon the snap temperature of bi-metallic disk 16. The higher the snap temperature of the bi-metallic disk, the higher the temperature for the transfer from low-flow mode to high-flow mode.

Tabs 49 of bi-metallic disk 16 are optional and are used to limit the axial travel of bi-metallic disk 16 during operation. The longer the axial length of tabs 49, the lower the axial travel of bi-metallic disk 16. Tabs 49 also clarify the explanation of concave and convex shapes when the fluid is hot or cold.

Slots 44 are formed in the outer circumferential edge 42 of bi-metallic disk 16 so as to fix, radially, bi-metallic disk 16 in dual flow impeller 10. As illustrated in Fig. 1 , slots 44 are aligned with and extend partially around blades 24. Slots 44 have free play around blades 24 to allow for axial movement of the bi-metallic disk 16.

The operation of dual flow impeller 10 and a pump employing dual flow impeller 10 will now be described with respect to Figs. 5-8. Figs. 5-8 illustrate dual flow impeller 10 housed in pump 50.

Fig. 5 illustrates a cross section of pump 50 having housing 52, inlet 54, and outlet 56. Rotating shaft 58 is affixed to a pulley which is driven by a motor, not shown, so as to rotate impeller 10 and pump fluid 60 through pump 50. Fail safe spring 62 is fixed to shaft 58 and second impeller 14. Impeller 10 is shown in the low-flow mode in Fig. 5 where bi-metallic disk 16 is shown in a concave shape.

Collar 27 is press fitted onto shaft 58 to hold impeller 10 in place. Specifically, first impeller 12 is fixed axially, while second impeller 14 and bi-metallic disk 16 are free to move axially along shaft 58.

Fig. 6 illustrates what happens when the temperature in fluid 60 reaches a high enough temperature to heat bi-metallic disk 16 to the snap temperature. In Fig. 6 bi-metallic disk 16 has snapped from a concave to a convex shape. This convex shape causes fluid 60 which moves through pump 50 to exert pressure onto the back side (right side in Figs. 5-8) of bi-metallic disk 16 which in turn causes bimetallic disk 16 to move axially to the left, toward inlet 54. Such movement by bimetallic disk 16 causes second impeller 14 to also move axially towards inlet 54. Fail safe spring 62 also urges second impeller 14 to move axially towards inlet 54.

Preferably, fail safe spring 62 exerts enough pressure on second impeller 14 such that if bi-metallic disk 16 fails, spring 62 is forced into high-flow mode. If the pump fails in low flow mode, the pump may overheat, thus it is preferred that if disk 16 fails, the pump should be in high-flow mode to prevent overheating.

Fig. 7 illustrates the completed axial movement of second impeller 14 and the change of dual flow impeller 10 from a low-flow mode to a high-flow mode. The convex position or shape of bi-metallic disk 16 keeps second impeller 14 pushed to the left and has both blades 24 and 34 actively pumping. Fig. 7 illustrates dual flow impeller 10 in a high-flow pumping mode.

Fig. 8 illustrates the change in shape of bi-metallic disk 16 when the temperature of bi-metallic disk 16 has changed from a high temperature to a low temperature and thus, bi-metallic disk 16 snaps from convex to concave in the transition from hot to cold. This change in shape of bi-metallic disk 16 causes the fluid to push the second impeller 14 axially to the right, and second impeller 14 returns to the position illustrated in Fig. 5. This also transitions pump 50 from high-flow mode back to low-flow mode. As will be appreciated, the length of the blades 24 and 34 both radially and axially effect the fluid flow through pump 50. As can be seen in Figs. 5-8, the low temperature state of the pump operation continues until the temperature of the fluid rises above the snap temperature for bi-metallic disk 16. At the snap temperature, bi-metallic 16 flips from its concave configuration to a convex configuration as shown in Fig. 6. This convex shape causes the dynamic fluid pressure traveling over the convex surface to reduce with respect to the concave surface and the dynamic fluid pressure pushes the bi-metallic disk to the left as shown in Fig. 6. Because tabs 36 fix second impeller 14 to bi-metallic disk 16 thus causes the movement of second impeller 14. The dynamic pressure continues to push the bi-metallic disk to the left thereby causing disk 16 to pull the attached second impeller 14 also to the left. Spring 62 helps push second impeller 14 to the left, into the high flow mode. Dual impeller 10 then continues in a stable high-flow operation mode until the temperature of the fluid falls below the snap temperature of bi-metallic disk 16. Fig. 8 clearly illustrates the point where bi-metallic disk 16 snaps from convex to concave in shape as the temperature falls below the snap temperature of bi-metallic disk 16. The dynamic fluid pressure flowing over bimetallic disk 16 now forces bi-metallic disk 16 to move to the right to return to the stable or low-flow mode.

The dual flow impeller of the present invention is especially suited for use in automobile coolant system, and specifically, water pumps in automobile coolant systems. The dual-flow impeller of the present invention provides a low cost and simple mechanical means for transferring a pump from a low-flow mode to a high- flow mode.

Reference characters

dual flow impeller 44 slots first impeller (low-flow impeller) 46 inner circumferential edge second impeller (high-flow impeller) 47 concave surface bi-metallic disk 48 opening axis 49 tabs

first disk 50 pump circumferential edge first disk 52 housing first blades 54 inlet openings 56 outlet ring 58 shat collar slots 60 fluid flow

62 belleville spring second disk circumferential edge second blades tabs center opening chord

bi-metallic ring outer circumferential edge

Claims

1 . A dual flow impeller for a fluid pump comprising: a first impeller having a first disk, first blades fixed at one end to a circumferential edge of the first disk and extending axially from the first disk, a ring fixed to the other end of the first blades and axially spaced form the first disk, and slots in the first disk aligned with a chord of the first disk; a second impeller having a second disk concentric with the first disk and axially movable in relation to the first disk, second blades fixed at one end to the second disk and extending axially from the second disk, one of each of the second blades aligned with one of each of the slots and the second blades axially movable through the slots; and a bi-metallic disk concentric with the first and second disk, the bi-metallic disk axially movable between the first disk and the ring, the bi-metallic disk having a center opening for fluid flow, the bi-metallic disk fixed to the second impeller such that when the bi-metallic disk axially moves from the first disk to the ring, the second blades axially move through the slots.

2. The dual flow impeller of claim 2, wherein a circumferential outer edge of the bi-metallic disk has slots, one of each of the slots aligned with one of each of the first blades.

3. The dual flow impeller of claim 1 , wherein the other end of each of the second blades has a tab that is aligned with and extends through the slots, and the tab is fixed to the bi-metallic disk.

4. The dual flow impeller of claim 1 , wherein a circumferential inner edge of the bi-metallic disk has tabs which extend axially towards the first disk.

5. The dual flow impeller of claim 1 further comprising: a spring affixed to the second impeller and fixable to a shaft of a pump.

6. A pump providing dual flow rates for fluid, comprising a housing having an inlet, an outlet, a dual flow impeller mounted on a shaft in the housing and a motor for rotating the shaft, wherein the dual flow impeller comprises a first impeller having a first disk fixed concentrically on the shaft, first blades fixed at one end to a circumferential edge of the first disk and extending axially from the first disk, a ring fixed to the other end of the first blades and axially spaced form the first disk, and slots in the first disk aligned with a chord of the first disk; a second impeller having a second disk concentric with the first disk and the shaft, and axially movable in relation to the first disk, second blades fixed at one end to the second disk and extending axially from the second disk, one of each of the second blades aligned with one of each of the slots and the second blades axially movable through the slots; and a bi-metallic disk concentric with the first and second disk and the shaft, the bi-metallic disk axially movable between the first disk and the ring, the bimetallic disk having a center opening for fluid flow, the bi-metallic disk fixed to the second impeller such that when the bi-metallic disk axially moves from the first disk to the ring, the second blades axially move through the slots.

7. The pump of claim 6, wherein a circumferential outer edge of the bi-metallic disk has grooves, one of each of the grooves aligned with one of each of the first blades.

8. The pump of claim 6, wherein the other end of each of the second blades has a tab that is aligned with and extends through the slots, and the tab is fixed to the bi-metallic disk.

9. The pump of claim 6, wherein a circumferential inner edge of the bi-metallic disk has tabs which extend axially towards the first disk.

0. The pump of claim 6 further comprising: a spring affixed to the second impeller and fixed to the shaft to exert pressure on the second impeller.