US20130025833A1

US20130025833A1 - Static dissipating agent dispersion apparatus and method

Info

Publication number: US20130025833A1
Application number: US13/193,905
Authority: US
Inventors: Craig R. Legros
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2011-07-29
Filing date: 2011-07-29
Publication date: 2013-01-31

Abstract

A static dissipating agent (SDA) dispersion apparatus and method disperses an SDA into a coolant system from a filter having a filter material and an SDA suspended within the filter material.

Description

BACKGROUND

The present disclosure is directed to electrical systems, and more particularly to liquid cooled electrical systems.
Electrical systems, such as wound field generators, often generate waste heat during operation. If the waste heat is allowed to accumulate, electronics or electrical equipment within the electrical system can be damaged. Numerous cooling techniques have been used to address the waste heat. One effective cooling technique that has been used is liquid cooling.
A liquid cooled electrical system passes a non-conductive liquid coolant over the components within the electrical system, thereby absorbing heat from the components into the coolant. The coolant is then passed out of the electrical system and allowed to cool. Once cooled, the coolant is recycled through the electrical system.
While the non-conductive coolant does not short out the electrical components within the electrical system due to its non-conductive nature, friction between the coolant and the cooling passage walls generates a static charge within the coolant. The static charge is then deposited on the cooled electronic components as the coolant passes over them. If the energy differential between the statically charged electrical components and the electrical component's housing gets too high, a static discharge between the components and the housing occurs. The static discharge can cause electrical faults, and damage to the electrical components.

SUMMARY

A liquid cooled electrical system includes at least one component, and a coolant passageway contacting the at least one component such that a liquid coolant cools the component. A coolant filter within the electrical system filters the coolant passageway upstream of the component, wherein the coolant filter comprises a semi-permeable filter material and a Static Dissipating Agent (SDA).
A coolant filter includes a filter material, an SDA contained within the filter material, and a frame supporting the filter material.
A method for preventing static discharge in an electrical system includes the steps of passing a liquid coolant through a coolant filter, dispersing an SDA within the coolant as the coolant is passed through the filter, and passing the coolant and SDA over a diode assembly which is an electrical component within the electrical system.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a liquid cooled generator.

FIG. 2 is a schematic illustration of a cross section of a liquid coolant filter.

FIG. 3 is a schematic illustration of a filter element dispersing an SDA into a coolant.

FIG. 4 is a schematic illustration of a coolant filter immersed in an SDA fluid.

FIG. 5 is a flowchart illustrating a method for preventing a static discharge buildup in an electrical component when a liquid coolant media is used.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a liquid cooled wound field generator system 10. The liquid cooled wound field generator system 10 is also referred to generally herein as a power generation system, or more simply as an electrical system. The wound field generator system 10 includes a generator 20 that has a shaft 26 for translating rotational movement to the rotor 28. Also attached to the shaft 26 is a rotating diode assembly 22. A practical implementation of the power generation system 10 includes further electrical and mechanical components that are omitted for explanatory purposes. The electrical and mechanical components are contained within a housing 38.
Also illustrated in the generator 20 is a liquid coolant passageway 24. The liquid coolant passageway 24 receives coolant from a filtered coolant passageway 32 and outputs spent coolant to a spent coolant passageway 42. A filter 30 and pump 36 arrangement draws unfiltered coolant from a coolant reservoir 40 along a reservoir coolant passageway 44, while the spent coolant passageway 42 deposits spent coolant back in the reservoir 40 to be cooled. In an alternate configuration, the filter 30, pump 36, and the coolant reservoir 40 are contained within the housing 38.
FIG. 2 illustrates a filter 30 that can be used in the arrangement of FIG. 1. The filter 30 is constructed of a top frame 110 and a bottom frame 120. The top and bottom frames 110, 120 hold a filter element 130 in place. The filter element 130 is a semi-permeable material that allows liquid coolant to pass, while at the same time preventing impurities from passing. The top frame 110 is sealed to a filtered coolant passageway 132 with an 0-ring seal 150. Coolant flows along the illustrated coolant flow path 140 through the filter element 130, into a low pressure coolant region 160, and out the filtered coolant passageway 132.
As the coolant flows through the passageways 24, 32, 42, 44 a static charge is generated within the coolant due to friction between the coolant and the passageway walls. The static charge is deposited on the cooled components as the coolant runs over the components. The buildup of static charge on the electrical rotor 28 and rotating diode assembly 22, as well as on other electrical and mechanical components, such as bearings, can cause sudden electrical discharges between the components 22, 28 and the component housing 38. In order to prevent static buildup within the coolant, a static dissipating agent (SDA) is dispersed within the coolant. Once dispersed, the SDA compound can be in the form of a mixture with the coolant (as illustrated in the included drawings) or be dissolved into the coolant, depending on the particular SDA compound and coolant used within the electrical system. The SDA compound dissipates static buildup within the coolant flow, thereby preventing a static charge from being deposited on the cooled component 22, 28. The significantly lower static buildup on the cooled component 22, 28 prevents the energy differential between the component 22, 28 and the component housing 38 from building up, and thereby prevents static discharges between the component and the component housing 38.
FIG. 3 illustrates a filter 30 dispersing an SDA compound 220 into a coolant 310, 320. In order to disperse the SDA compound 220 into the coolant 310, 320 of a pre-existing cooling system, the filter element 130 of a standard filter 30 for the pre-existing cooling system is treated with the SDA compound 220 prior to installation in the cooling system. During operation of the cooling system, fresh coolant 310 on a high pressure side of the treated filter element 130 is passed through the treated filter element 130. The SDA compound 220 suspended within the filter element 130 is picked up by the coolant 310, 320 from the filter element 130 as the coolant 310, 320 passes through the filter element 130, and enters the coolant 320 on the low pressure side of the filter element 130. In this way the SDA compound 220 is dispersed into the coolant 310, 320 from the filter element 130.
FIG. 4 illustrates a process by which a filter element 130 of the filter 30 is treated to suspend the SDA compound 220 within the filter element 130. The filter 30 is submerged in a fluid 210. The fluid 210 is at least composed of the SDA compound 220 and can include other liquids as well. Alternately, the SDA compound 220 can be a solid particulate mixed with a liquid suspending agent. While the filter element 130 is submerged, the fluid 210 permeates the filter element 130 causing the SDA compound 220 to be suspended within the filter element 130.
In the illustrated example of FIG. 4, the fluid 210 is contained in a tank 240. It is understood, however, that alternate means of allowing the SDA compound 220 to permeate the filter element 130, such as exposing the filter element 130 to a liquid wash containing the SDA compound 220, can also provide the same function. The filter element 130 illustrated in FIG. 4 is shown as being saturated with the SDA compound 220.
Once the filter element 130 is saturated with the SDA compound 220, the filter is installed in a cooling system such as the cooling system illustrated in FIG. 1. The above described process can be used to treat any stock coolant filter, and thereby allows a stock coolant filter to operate as a delivery mechanism for delivering an SDA compound 220 into a coolant within an existing liquid cooling system without requiring a mechanical overhaul of the existing cooling system.
When the filter element 130 is saturated with the SDA compound 220 during the treatment, the filter 30 can continue dispersing the SDA compound 220 into the coolant for at least the lifespan of the filter 30. In this way, the coolant filter 30 is replaced due to routine maintenance before the suspended SDA compound 220 is exhausted, thereby ensuring that the filter 30 is always dispersing the SDA compound 220 within the coolant.
FIG. 5 illustrates a flowchart demonstrating the method by which the SDA compound 220 is dispersed into the coolant, thereby preventing a static discharge between the coolant and components 22, 28. Initially, the filter 30 and pump 36 arrangement draws fresh coolant 310 from the reservoir 40 in a “draw fresh coolant from reservoir” step 410. The fresh coolant 310 is passed through the filter element 130 containing the SDA compound 220 in a “pass coolant through filter” step 420. As the coolant is passed through the filter 30, the SDA compound 220 suspended in the filter element 130 is dispersed into the coolant in a “disperse SDA from filter into coolant” step 430. The SDA containing coolant 320 is then passed over the components 22, 28, thereby cooling them, in a “pass SDA containing coolant over components” step 440. The spent coolant is then returned to the reservoir 40 in the “return used coolant to reservoir” step 450.
The above described system is illustrated in FIG. 1 with regards to a rotating diode assembly in an electrical generator. However, it is understood that a similar system could be utilized to disperse an SDA compound into liquid coolant for any liquid cooled electronic device, whether dynamic or static, and still fall within the above described disclosure.
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.

Claims

1. A liquid cooled system comprising:

at least one component;

a coolant passageway contacting said at least one component such that a liquid coolant cools said at least one component; and

a coolant filter interrupting said coolant passageway upstream of said at least one component, wherein said coolant filter comprises a filter element and a static dissipating agent (SDA).

2. The liquid cooled system of claim 1, wherein said SDA is contained within said filter element.

3. The liquid cooled system of claim 1, wherein said coolant filter is a modified standard coolant filter.

4. The liquid cooled system of claim 3, wherein said modified standard coolant filter is modified such that said SDA is suspended in said filter element.

5. The liquid cooled system of claim 1, wherein said SDA is a liquid based SDA.

6. The liquid cooled system of claim 1, wherein a liquid on a high pressure side of said coolant filter is a coolant and the liquid on a low pressure side of said coolant filter is a mixture of said coolant and said SDA.

7. The liquid cooled system of claim 1, wherein said at least one component comprises a rotating diode assembly.

8. The liquid cooled system of claim 1, wherein said filter element comprises a semi-permeable filter material.

9. The liquid cooled system of claim 1, wherein said at least one component is an electrical component.

10. The liquid cooled system of claim 1, wherein said at least one component is a mechanical component.

11. The liquid cooled system of claim 10, wherein said mechanical component is a bearing.

12. A coolant filter comprising:

a filter material;

a static dissipating agent (SDA) contained within said filter material; and

a frame supporting said filter material.

13. The coolant filter of claim 12, wherein said SDA is a liquid suspended within said filter material.

14. The coolant filter of claim 12, wherein said SDA is a solid suspended in a liquid, and said SDA is suspended within said filter material.

15. The coolant filter of claim 12, wherein said coolant filter is a standard coolant filter size.

16. The coolant filter of claim 12, wherein said SDA is dispersed into a coolant passed through said coolant filter.

17. The coolant filter of claim 12, wherein said filter material is a semi-permeable material.

18. A method for preventing static discharge in an electrical system comprising the steps of:

passing a coolant through a coolant filter;

dispersing a static dissipating agent (SDA) within said coolant as said coolant is passed through said filter; and

passing said coolant and static dissipating agent over said rotating diode assembly.

19. The method of claim 18, further comprising the step of suspending said SDA in said coolant filter prior to installing said coolant filter in a cooling system, thereby causing said SDA to be suspended within said filter element.

20. The method of claim 19, wherein said coolant includes no SDA prior to passing through said coolant filter.

21. The method of claim 19, wherein said step of suspending said SDA in said coolant filter comprises soaking a filter element of said coolant filter in an SDA fluid.

22. The method of claim 19, wherein said step of suspending said SDA in said coolant filter comprises washing a filter element of said coolant filter in an SDA fluid.