Testing method of EV lubricants with E-machine materials

Abstract

A method for testing a lubricant composition for use with electrical drive unit (EDU) components, comprises: performing one or more measurements to establish a plurality of baseline test parameters on a sample number of EDU components wherein the sample number comprises first and second subsets which are mutually exclusive; performing an immersion ageing compatibility test on the second subset, which comprises: at least partially-immersing the second subset into the lubricant composition; simulating lifetime operating conditions for the at least partially-immersed second subset and the lubricant composition; and performing one or more measurements to establish a plurality of aged test parameters and comparing the plurality of aged test parameters to the baseline test parameters to establish whether a change between the baseline test parameters and the aged test parameters has occurred. The measurements may be a dielectric dissipation test, electrical resistance test, or a breakdown voltage test.

Description

TECHNICAL FIELD The present disclosure relates to a method of testing EV lubricants with E-machine materials. Aspects of the invention relate to a method and to a system for performing said method. BACKGROUND It is known to provide components, such as enamelled copper conductors, so-called hairpins, for use in electrical drive units, EDUs, which operate in contact with special lubricant compositions incorporated into EDUs at the manufacture stage. Unlike in conventional combustion drive units, wherein lubricant compositions may be replaced with fresh lubricant compositions during the operating lifetime of the drive unit, in EDUs the lubricant is sealed and may not be replaced during its operational lifetime. Conventional combustion oil lubricants may not be applied to EDUs as they are generally incompatible with EDU materials and modes of operation. Therefore, as EDU lubricant compositions are highly specialised, they must be rigorously tested before use to ensure they are compatible with other EDU components which they contact under standard operating conditions throughout the EDU lifetime. In specific examples, the compatibility of enamel coatings, examples of which may include polyether ether ketones (PEEK), perfluoroalkoxy alkanes (PFA), polyamides (PA), and polyvinyl formals (formvar), covering metallic conductors, such as copper or copper alloys, of specific EDU components, such as hairpins, with the lubricant composition under standard EDU operating conditions is of particular importance as some polymeric enamel coatings may be subject to degradation by incompatible lubricants. Test methodologies for lubricant compositions operable with transformer engine components are known. However, owing to substantially different modes of operation, operation conditions and material components, such test methodologies are unsuitable for testing lubricant compositions for their compatibility with EDU components. Furthermore, with the current drive toward more sustainable technologies there also exists a need to increase the use of lubricant compositions incorporating recycled components, which may lead to lubricant compositions with increased impurity levels, which may in turn have degradative effects on EDU components over an operation lifetime. Therefore, a method for testing new or existing lubricant compositions for their compatibility with EDU components is lacking in the current state of the art. It is an aim of the present invention to address one or more of the disadvantages associated with the state of the art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide an method and system for performing said method as claimed in the appended claims. According to an aspect of the invention there is provided a method for testing a lubricant composition. The lubricant composition may be for use with electrical drive unit (EDU) components. The method comprises: performing one or more measurements to establish a plurality of baseline test parameters on a sample number of EDU components wherein the sample number of EDU components comprises a first subset and a second subset, wherein the two subsets are mutually exclusive; performing an immersion ageing compatibility test on the second subset; wherein the immersion ageing compatibility test comprises: at least partially-immersing the second subset into the lubricant composition; simulating lifetime operating conditions for the at least partially-immersed second subset and the lubricant composition; and performing one or more measurements to establish a plurality of aged test parameters and 1 comparing the plurality of aged test parameters to the plurality of baseline test parameters to establish whether a change between the plurality of baseline test parameters and the plurality of aged test parameters has occurred. The method facilitates the simulation of lifetime operating conditions of the lubricant and EDU components so that the compatibility of the lubricant with said EDU components may be established. According to an embodiment of the above-mentioned aspect, the plurality of baseline test parameters establish functional integrity of the sample number of EDU components; optionally wherein the sample number of EDU components comprises a conductor coated with a coating; and determining the functional integrity of the sample number of EDU components comprises determining the structural integrity of the coating. According to another embodiment of the above-mentioned aspect, the conductor is selected from the group consisting of: a metal, a metal alloy or a carbon-based conductor; and the coating is an enamel coating; optionally, wherein the conductor is copper or a copper alloy. According to another embodiment of the above-mentioned aspect, the lubricant composition comprises a Group III or Group III+ oil; optionally wherein the lubricant composition comprises at least one recycled component. According to another embodiment of the above-mentioned aspect, the one or more measurements performed on the first subset are selected from: a dielectric dissipation test, a DC electrical resistance test or a breakdown voltage test, so as to establish the plurality of baseline test parameters; and the one or more measurements performed on the second subset are selected from: a dielectric dissipation test or a DC electrical resistance test performed before the immersion ageing compatibility test; and a dielectric dissipation test, a DC electrical resistance test or a breakdown voltage test performed after the immersion ageing compatibility test to establish the plurality of aged test parameters. According to another embodiment of the above-mentioned aspect, a breakdown voltage for the first subset, which has a magnitude, and a breakdown voltage for the second subset, which has a magnitude, are measured using the breakdown voltage test; and wherein the magnitude of the breakdown voltage for the first subset and the magnitude of the breakdown voltage for the second subset are compared to determine the compatibility of the lubricant for use with the sample number of EDU components; optionally, the lubricant may be determined as compatible for use with the sample number of EDU components if the magnitude of the breakdown voltage of the second subset is at least 50% of the magnitude of the breakdown voltage of the first subset. According to another embodiment of the above-mentioned aspect, the breakdown voltage test further comprises exposing the sample number of EDU components to moisture; optionally wherein the moisture further comprises an electrolyte. According to another embodiment of the above-mentioned aspect, simulating lifetime operating conditions comprises: heating the lubricant composition to an elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions and maintaining the lubricant composition at the elevated temperature for a period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components; and / or applying a voltage across the sample number of EDU components of the at least partially-immersed second subset to heat the sample number of EDU components to the elevated temperature above the standard operating temperature of the lubricant composition and the sample number of EDU components and maintaining said voltage for the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components. According to another embodiment of the above-mentioned aspect, the elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions of the at least partially-immersed second subset is at least 100 °C, or at least 110 °C, or at least 120 °C, or at least 130 °C, or at least 140 °C, or at least 150 °C, or at least 160 °C, or at least 170 °C, or at least 180 °C, or at least 190 °C, or at least 200 °C, or at least 210 °C, or at least 220 °C, or at least 230 °C, or at least 240 °C, or at least 250 °C, and at most 260 °C. According to another embodiment of the above-mentioned aspect, the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components may be at least 100 hours, or at least 200 hours, or at least 300 hours, or at least 400 hours, or at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 1000 hours, or at least 1100 hours, or at least 1200 hours, or at least 1300 hours, or at least 1400 hours, or at least 1500 hours, or at least 1600 hours, or at least 1700 hours, or at least 1800 hours, or at least 1900 hours, and at most 2000 hours. According to another embodiment of the above-mentioned aspect, the elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions of the at least partially-immersed second subset is around 150 °C; and the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components is around 1000 hours. According to another embodiment of the above-mentioned aspect, the immersion ageing compatibility test further comprises analysing the lubricant composition for indications of lubricant degradation; optionally, the lubricant degradation isoxidative lubricant degradation. According to another embodiment of the above-mentioned aspect, the sample number of EDU components comprises a winding component; optionally the winding component comprises a hairpin. According to another aspect of the invention there is provided a system for performing the method of any above-mentioned aspect or embodiment, wherein the system comprises at least: a sealable container for housing the lubricant and at least one EDU component; wherein the sealable container comprises at least a member for receiving components facilitating electrical connection between at least two electrodes and at least one EDU component such that a voltage may be applied across the at least one EDU component and the at least one EDU component may be at least partially immersed in the lubricant composition; a thermal heat source configured to heat to the lubricant composition; and an electric power source configured to supply DC or AC voltage across the at least two electrodes. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a first flow chart showing the method steps of Part A of the method; Figure 2 shows a second flow chart showing the method steps of Part B of the method; Figure 3 shows an example of a hairpin for use as an EDU component; Figure 4 shows schematic illustrations of manufacture defects to the enamel coating of exemplary EDU hairpins; Figure 5 shows schematic illustrations of an exemplary system for performing the method, at least including sealable containers configured to be connected to at least a power source; and Figure 6 shows a schematic illustration of an EDU hairpin cut into fragments following completion of the tests simulating lifetime operating conditions (A); and schematic illustrations of optical microscopy (B) and SEM (C) micrographs of such a hairpin demonstrating the effects of simulated aging. DETAILED DESCRIPTION A method in accordance with an embodiment of the present invention is described herein. The purpose of the method is to establish a standard test methodology for lubricant compositions for use with electrical drive unit (EDU) components. With reference to the accompanying Figures, the method comprises two parts, each part comprising a series of steps. The first part, Part A (100), as shown as a flow chart in Figure 1, comprises a baseline measurements of new EDU components. The second part, Part B (200), as shown as a flow chart in Figure 2, comprises an immersion ageing compatibility test. In embodiments of the invention, the method may be used for testing lubricant compositions belonging to Group III or Group II l+oils. Group III oils are generally understood to be to hydrocracked oils and comprise at least 90 wt% saturates, less than 0.3 wt% sulphur and possess a viscosity index of greater than 120. Group III+ oils are generally produced by gas to liquids processes and have higher viscosity indexes than Group III oils; generally having a viscosity index of at least 130. In embodiments of the invention, the method may be used for testing lubricant compositions containing at least one recycled component. In further embodiments of the invention, the method maybe used for testing lubricant compositions belonging to Group III or Group lll+oils and containing at least one recycled component. Suitably, the recycled component may constitute at least 1 wt%, at least 5 wt%, at least 10 wt%, suitably at least 20 wt%, and optionally up to 30 wt% of the total lubricant composition. In embodiments of the invention, the method may be used for testing EDU components, wherein the EDU components may comprise a core conductor and an external coating. The conductor may be a selected from the group consisting of: a metal, a metal alloy or a carbon-based conductor; wherein the metal or the metal alloy may comprise copper. The coating may be an enamel coating. In embodiments of the invention the enamel coating includes a polymeric material, such as a polyether ether ketone (PEEK), perfluoroalkoxy alkane (PFA), polyamide (PA), or polyvinyl formal (formvar). In embodiments of the invention, the EDU component may comprise a hairpin (301) comprising a copper or copper alloy core coated with an enamel coating, such as shown in Figure 3. Hairpins are electrical winding components utilised in the assembly of stators. With reference to Figure 1, Part A (100), the baseline measurement of new EDU components, is performed on a sample number of EDU components to establish baseline performance parameters of said sample number of EDU components, which are then available for comparison with the results of Part B (200), the immersion ageing compatibility test. Part A (100) comprises four steps comprising electrically testing the EDU components, Step 1A (101), Step 2A (102), Step 3A (103) and Step 4A (104). Step 1A (101) comprises of taking a statistically meaningful sample number of EDU components (at least five EDU components) and inspecting them for any visual manufacturing defects (401) using, for example, an optical microscope to determine integrity of enamel coating or hairpin conformation. Any EDU components found to contain any visible defects (401) are discarded from the test. Figure 4 shows an example of EDU component hairpin manufacture defects (401). All remaining EDU components are divided into two mutually exclusive subsets, a first subset and a second subset, of as close to an equal number EDU components as possible. Step 2A (102) comprises performing dielectric dissipation factor tests on the first and second subsets. Any suitable mode of dielectric dissipation factor test may be used. The test procedure may be performed taking IEC 60851-4 as a test reference. Step 3A (103) consists of performing DC electrical resistance tests on the first and second subsets. Any suitable mode of DC electrical resistance test may be used. By way of a non-limiting example, in one embodiment, electrical resistance tests are performed at an applied voltage of 1000 V and up to the maximum operating voltage of the EDU components. The second subset is put aside for use (105) in Part B (200). The first subset is applied to Step 4A (104). Step 4A (104) comprises performing breakdown voltage tests on the first subset. Any suitable mode of breakdown voltage test may be used. The test procedure may be performed taking IEC 60851-4 as a test reference. The results of the Step 2A (102), Step 3A (103) and Step 4A (104) are analysed to establish a plurality of baseline parameters. Analysis may involve a statistical analysis. In a non-limiting example, the average of each baseline parameter may be calculated from the measurements performed on the individual EDU components of the sample number of EDU components and used as the result of each of Step 2A (102), Step 3A (103) and Step 4A (104). The results of the measurements performed on the first and second subsets in Step 2A (102) are compared to establish that the two subsets are substantially the same in terms of their functional and structural integrity. The results of the measurements performed on the first and second subsets in Step 3A (103) are compared to establish that the two subsets are substantially the same in terms of their functional and structural integrity. Substantially similar results between the two subsets obtained from Step 2A (102) and / or Step 3A (103) demonstrate that the EDU components comprising the two subsets are functionally similar and therefore indicate that they are also structurally similar. The EDU components of the first subset used for the breakdown voltage test are discarded as the tests are performed to EDU component failure. The results obtained from at least any one of Step 2A (102), Step 3A (103) and Step 4A (104) may be used as the plurality of baseline test parameters to be compared with the so-called plurality of aged test parameters, the results of the at least one of a dielectric dissipation factor test, a DC electrical resistance tests, or a breakdown voltage test performed on the second subset during Part B (200), to determine the compatibility of the lubricant with the EDU components. The breakdown voltage test may include an additional step wherein the sample number of EDU components are exposed to moisture before measurement of the breakdown voltage, wherein the moisture may comprise any appropriate solution comprising at least a solvent and at least one solute electrolyte, optionally wherein the solvent is water and the solute electrolyte is a salt, further optionally wherein the salt may be a sodium or potassium salt, including sodium chloride or potassium chloride. The electrical contacts of the EDU components are checked to ensure they are dry before the breakdown voltages are measured. The remainder of the main bodies of the EDU components may or may not be dried. The exposure to moisture serves to amplify or exacerbate the effects of any structural defects of the EDU components such that the conditions applied to the test requires that the EDU components must withstand conditions substantially more harsh than those conditions found during standard operation of EDUs. With reference to Figure 2, Part B (200), the immersion ageing compatibility test, is performed on the second subset, provided the results of Step 2A (102) and Step 3A (103) yield statistically equivalent results for the first and second subset, to test the breakdown voltage of the EDU components following exposure to simulated lifetime operating conditions. Part B (200) may also involve analysing the lubricant for indications of degradation, for example, oxidative degradation. Part B (200) may comprise five steps for testing the EDU components and the lubricant: Step 1B (201), Step 2B (202), Step 3B (203), Step 4B (204) and Step 5B (205). Step 1B (201) comprisestaking at least one sealable container, which may comprise a lid, configured to house a volume of a lubricant composition and at least one EDU component to be tested. The sealable container comprises at least a member for receiving components facilitating electrical connection between at least two electrodes further comprising the sealable container and at least one EDU component, such that a DC or AC voltage may be applied across the at least one EDU component resulting in a current passing through said at least one EDU component such that the at least one EDU component may be simultaneously at least partially immersed in the lubricant composition. The sealable container further contains a thermal heat source configured to heat the lubricant composition housed in the sealable container and an electrical power source configured to supply DC or AC voltage across the at least two electrodes. In one non-limiting example demonstrating the method, the sealable container is cleaned before use with a suitable organic solvent, for example acetone, to remove any residual contamination. Any residue from the organic solvent is allowed to evaporate and the sealable container is filled with an appropriate volume of the lubricant composition, such as a Group lll / lll+oil, to be tested. The EDU components comprising the second subset are at least partially immersed in the lubricant such that the electrical contacts of the EDU components are not brought into contact with the lubricant The electrical contacts of the EDU components are connected to the electrodes of the sealable container and the sealable container is sealed. The electrodes are connected to the electrical power source. Using the thermal heat source, the lubricant is heated to an elevated temperature above the maximum operating temperature of the lubricant and the EDU components when functioning under standard operating conditions and maintained at said elevated temperature for a period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and EDU components. Using the power source, a DC or AC voltage is simultaneously and separately applied across the electrical contacts of the EDU components of the second subset such that a current passes through the EDU components which heats the EDU components to said elevated temperature and maintains said EDU components at said elevated temperature for said period of time. If there is more than one EDU component per sealable container or more than one sealable container containing at least one EDU component, the EDU components may be connected in series or in parallel or may be connected to separate electrical power sources. Figure 5 shows an example of a system which may be used for carrying out Step 1B (201) of the method. The elevated temperature to which the lubricant composition and EDU components are heated by the thermal heat source and electrical power source and the period of time for which the heating and current are maintained are selected to simulate the lifetime operation conditions of the lubricant composition and the EDU components. Maintaining the lubricant composition and the EDU components at said elevated temperature above the maximum operating temperature under standard operating conditions of the EDU components effectively reduces the lifetime of the lubricant composition and the EDU components, allowing the test to simulate the lifetime operating conditions over a relatively short period of time. For every 10 °C the temperature of the lubricant composition and EDU components are raised above the EDU component standard( / maximum?) operating conditions approximately reduces the lifetime of the lubricant composition and EDU components by half. In one non-limiting example, the lubricant composition and the EDU components are maintained at 150 °C for a period of time. In another non-limiting example, the period of time may be 1000 hours. In another non-limiting example, a DC or AC voltage of 2.7 kV is applied across the EDU components In another non-limiting example, Step 1B (201) may be paused at the halfway point (for example, after 500 hours) and some of the EDU components are removed and tested as per Step 2B (202), Step 3B (203) and Step 4B (204), as described below, to track the simulated ageing process over time. In specific embodiments, the elevated temperature is at least 100 °C, or at least 110 °C, or at least 120 °C, or at least 130 °C, or at least 140 °C, or at least 150 °C, or at least 160 °C, or at least 170 °C, or at least 180 °C, or at least 190 °C, or at least 200 °C, or at least 210 °C, or at least 220 °C, or at least 230 °C, or at least 240 °C, or at least 250 °C, and at most 260 °C. In further embodiments, the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition may be at least 100 hours, or at least 200 hours, or at least 300 hours, or at least 400 hours, or at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 1000 hours, or at least 1100 hours, or at least 1200 hours, or at least 1300 hours, or at least 1400 hours, or at least 1500 hours, or at least 1600 hours, or at least 1700 hours, or at least 1800 hours, or at least 1900 hours, and at most 2000 hours. Upon expiration of the period of time to sufficient to simulate the lifetime operating conditions of the lubricant composition and EDU components, the system is allowed to cool. In one non-limiting example the system is allowed to cool for a period of at least six hours before the EDU components are removed. Once removed from the lubricant composition, the EDU components of the second subset are used in Step 2B (202), Step 3B (203) and Step 4B (204), which comprise ascertaining the plurality of aged test parameters for comparison with the baseline test parameters. Step 2B (202) comprises performing dielectric dissipation factor tests on the second subset identical to the tests of Step 2A (102). Any suitable mode of dielectric dissipation factor test may be used. The test procedure may be performed taking IEC 60851-4 as a test reference. Step 3B (203) consists of performing DC electrical resistance tests on the second subset identical to the tests of Step 3A (103). Any suitable mode of DC electrical resistance test may be used. The test procedure may be performed taking IEC 60851-4 as a test reference. Step 4B (204) comprises performing breakdown voltage tests on the second subset identical to the tests of Step 4A (104). Any suitable mode of breakdown voltage test may be used. The test procedure may be performed taking IEC 60851-4 as a test reference. Step 5B (205) comprises analysing the lubricant composition used for Step 1B (201) following completion of Step 1B (201). The oil is analysed using any appropriate method or methods for indications of degradation, for example including oxidative degradation. If the lubricant composition has an associated manufacturer datasheet, suitable analysis may be performed to measure the properties of the lubricant composition such that they may be compared to the physical and chemical properties as dictated by the associated manufacturer datasheet to determine whether degradation has occurred. If a manufacturer datasheet is not associated with the lubricant composition, physical and chemical measurements may be performed on an unused sample of the same batch used for testing and used for comparison to determine whether degradation has occurred. If an unacceptable level of degradation has occurred as determined by Step 5B (205), the lubricant may be determined as incompatible for use with the EDU components. An unacceptable level of degradation may be determined by the person skilled in the art. The method further involves comparing the plurality of aged test parameters to the plurality of baseline test parameters to determine whether or not a change between the plurality of baseline test parameters and the plurality of aged test parameters has occurred, which may be used to determine whether the lubricant is compatible for use with the EDU components. In a non-limiting example, the lubricant may be determined to be incompatible for use with the EDU components if at least one of the magnitudes of the plurality of aged test parameters is less than 50% that of the corresponding baseline test parameter; otherwise the lubricant is compatible for use with the EDU components. In another non-limiting example, the lubricant may be determined to be compatible for use with the EDU components if all of the magnitudes of the plurality of aged test parameters are greater than 50% that of the averages of the corresponding baseline test parameters; otherwise the lubricant is incompatible for use with the EDU components. With reference to Figure 6, if any one EDU component is determined to be incompatible for use with a lubricant, wherein compatibility / incompatibility may be determined by comparing a single aged test parameter determined for said one EDU component in Part B (200) with the corresponding baseline test parameter from Part A (100), which may be an average value, the method may further comprise inspecting said one EDU component using at least optical microscopy and / or using scanning electron microscopy (SEM) and / or energy-dispersive X-ray spectroscopy (EDX) to ascertain the root cause of the failure, as exemplified in (B) and (C). As part of the inspection, the EDU components may be cut into fragments or sections for analysis, if necessary. Surface deformities or damage to a coating on the EDU components may be determined by imaging using the above techniques. Particular attention may be given to any sections of the EDU components to which mechanical stress is applied during manufacture as these sections experience the greatest amount of stress during operation and are most prone to damage or failure. In an embodiment of the invention, a system is provided for performing the any one of the methods described herein. Typically, the system comprises a sealable container for housing the lubricant and at the least one EDU component under test. The sealable container comprises at least a member for receiving one or more components facilitating electrical connection between at least two electrodes and at the one or more EDU components such that a voltage may be applied across them. According to the described methods, the sealable container may be configured to fully or partially immerse the EDU component(s) in the lubricant composition. Partial immersion may include, immersion of up to 30%, up to, 50%, up to 75% or up to 90% of the volume of the EDU component under test. The sealable container further comprises a thermal heat source configured to heat to the lubricant composition; as well as an electric power source configured to supply DC or AC voltage across the at least two electrodes. The thermal heat source may comprise an electrically resistive heating jacket or may comprise an oven into which the sealable container is placed. The system may 5 be sealed for the requisite period of time as defined by the methods described. The system may further comprise one or more sensors, e.g. incorporated into the sealable container, such to monitor temperature, material and electrical performance parameters of the EDU component during the test. Descriptions in the below table shall be used in combination with the figures. 10 Table 1: 100 Part A: Baseline Measurement Test 101 Step 1 A: Inspect sample number of EDU components for defects and divide into first and second subsets 102 Step 2A: Perform dielectric dissipation tests on first and second subsets 103 Step 3A: Perform DC electrical resistance tests on first and second subsets 104 Step 4A: Perform breakdown voltage tests on first subset 105 Put aside second subset for use in Part B 200 Part B: Immersion Ageing Compatibility Test 2000 Use second subset from Part A 201 Step 1B: • At least partially immerse EDU components of second subset in lubricant composition in sealable container • Thermally heat lubricant composition and electrically heat EDU components of second subset in sealable container for a period of time 202 Step 2B: Perform dielectric dissipation tests on second subset 203 Step 3A: Perform DC electrical resistance tests on second subset 204 Step 4B: Perform breakdown voltage tests on second subset 205 Step 5B: Perform aged oil analysis

Claims

1. A method for testing a lubricant composition for use with electrical drive unit (EDU) components, comprising:Performing one or more measurements to establish a plurality of baseline test parameters on a sample number of EDU components wherein the sample number of EDU components comprises a first subset and a second subset, wherein the two subsets are mutually exclusive;performing an immersion ageing compatibility test on the second subset; whereinthe immersion ageing compatibility test comprises:at least partially-immersing the second subset into the lubricant composition;simulating lifetime operating conditions for the at least partially-immersed second subset and the lubricant composition; andperforming one or more measurements to establish a plurality of aged test parameters and comparing the plurality of aged test parameters to the plurality of baseline test parameters to establish whether a change between the plurality of baseline test parameters and the plurality of aged test parameters has occurred.

2. The method of claim 1, wherein the plurality of baseline test parameters establish functional integrity of the sample number of EDU components; optionally wherein the sample number of EDU components comprises a conductor coated with a coating; and determining the functional integrity of the sample number of EDU components comprises determining the structural integrity of the coating.

3. The method of claim 2, wherein the conductor is selected from the group consisting of: a metal, a metal alloy or a carbonbased conductor; and the coating is an enamel coating; optionally,wherein the conductor is copper or a copper alloy.

4. The method of any preceding claim, wherein the lubricant composition comprises a Group III or Group lll+oil; optionally wherein the lubricant composition comprises at least one recycled component.

5. The method of any preceding claim wherein the one or more measurements comprises at least one of: a dielectric dissipation test;a DC electrical resistance test; and a breakdown voltage test.

6. The method of claim 5, wherein the one or more measurements performed on the first subset are selected from: a dielectric dissipation test, a DC electrical resistance test or a breakdown voltage test, so as to establish the plurality of baseline test parameters; andwherein the one or more measurements performed on the second subset are selected from: a dielectric dissipation test or a DC electrical resistance test performed before the immersion ageing compatibility test; and a dielectric dissipation test, a DC electrical resistance test or a breakdown voltage test performed after the immersion ageing compatibility test to establish the plurality of aged test parameters.

7. The method of any of claims 5 or 6, wherein a breakdown voltage for the first subset, which has a magnitude, and a breakdown voltage for the second subset, which has a magnitude, are measured using the breakdown voltage test; and wherein the magnitude of the breakdown voltage for the first subset and the magnitude of the breakdown voltage for the second subset are compared to determine the compatibility of the lubricant for use with the sample number of EDU components; optionally whereinthe lubricant may be determined as compatible for use with the sample number of EDU components if the magnitude of the breakdown voltage of the second subset is at least 50% of the magnitude of the breakdown voltage of the first subset.

8. The method of anyone of claims 5 to 7, wherein the breakdown voltage testfurther comprises exposing the sample number of EDU components to moisture; optionally wherein the moisture further comprises an electrolyte.

9. The method of any preceding claim wherein simulating lifetime operating conditions comprises:(i): heating the lubricant composition to an elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions and maintaining the lubricant composition at the elevated temperature for a period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components; and / or(II): applying a voltage across the sample number of EDU components of the at least partially-immersed second subset to heat the sample number of EDU components to the elevated temperature above the standard operating temperature of the lubricant composition and the sample number of EDU components and maintaining said voltage for the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components.

10. The method of claim 9, wherein the elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions of the at least partially-immersed second subset is at least 100 °C, or at least 110 °C, or at least 120 °C, or at least 130 °C, or at least 140 °C, or at least 150 °C, or at least 160 °C, or at least 170 °C, or at least 180 °C, or at least 190 °C, or at least 200 °C, or at least 210 °C, or at least 220 °C, or at least 230 °C, or at least 240 °C, or at least 250 °C, and at most 260 °C.

11. The method of any one of claims 9 or 10, wherein the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components may be at least 100 hours, or at least 200 hours, or at least 300 hours, or at least 400 hours, or at least 500 hours, or at least 600 hours, or at least 700 hours, or at least 800 hours, or at least 900 hours, or at least 1000 hours, or at least 1100 hours, or at least 1200 hours, or at least 1300 hours, or at least 1400 hours, or at least 1500 hours, or at least 1600 hours, or at least 1700 hours, or at least 1800 hours, or at least 1900 hours, and at most 2000 hours.

12. The method of any one of claims 9 to 11, wherein the elevated temperature above the maximum operating temperature of the lubricant composition and the sample number of EDU components under standard operating conditions of the at least partially-immersed second subset is around 150 °C; and the period of time sufficient to simulate the lifetime operating conditions of the lubricant composition and sample number of EDU components is around 1000 hours.

13. The method of any preceding claim, wherein the immersion ageing compatibility test further comprises analysing the lubricant composition for indications of lubricant degradation; optionally wherein the lubricant degradation is oxidative lubricant degradation.

14. The method of any preceding claim, wherein the sample number of EDU components comprises a winding component; optionally wherein the winding component comprises a hairpin.

15. A system for performing the method of any preceding claim, wherein the system comprises at least:5 a sealable container for housing the lubricant and at least one EDU component; whereinthe sealable container comprises at least a member for receiving components facilitating electrical connection between at least two electrodes and at least one EDU component such that a voltage may be applied across the at least one EDU component and the at least one EDU component may be at least partially immersed in the lubricant composition;a thermal heat source configured to heat to the lubricant composition; and10 an electric power source configured to supply DC or AC voltage across the at least two electrodes.

Images