FR2790334A1 - Hermetic terminal for carrying electrical current through a hermetic compressor housing, has electrical insulation coatings on the terminal body exterior and interior sides formed from polyetheretherketone - Google Patents

Abstract

Hermetic terminal for carrying electrical current through a hermetic compressor housing, has electrical insulation coatings on the terminal body exterior and interior sides formed from polyetheretherketone The terminal metallic body is adapted to form a hermetic seal with a terminal opening in a compressor housing. The body has conductor pins, each hermetically sealed in an opening formed with an integral collar and glass insulator. Uniform thickness coatings of polyetheretherketone (PEEK) are adhered to the body on each side. The coatings cover the collar exposed surfaces, the insulators and an intermediate portion of each pin.

Description

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1. Field of the invention
The present invention relates to a sealed terminal of the type used to pass an electric current through a hermetic compressor housing, this terminal comprising a metal body for forming a seal with a terminal opening formed in the hermetic compressor housing, which body having an inner surface for facing the inside of the compressor housing, and an outer surface for facing outwardly of the compressor housing, at least one conductor pin passing through at least one corresponding opening formed therein in the body, and intended to conduct electricity through the terminal to pass it into the compressor housing, this conductor pin being sealed in the opening and electrically insulated from the body.

 More particularly, the present invention relates to electrical insulation coatings applied to such sealed terminals.

2. Description of the relevant technology
Waterproof terminals of the general type of the present invention are well known in the art and examples of such terminals are illustrated for example in U.S. Patent No. 3,988,053 to Dodenhoff, dated October 16, 1976, and in US Pat. No. 3,551,191 to Elbling et al., Dated December 29, 1970. Terminals of this type traditionally include a generally cup-shaped metal body having, in the end wall of the body, a number of openings through each of which passes a conductor pin, this pin being hermetically sealed to the body, for example by means of a glass-metal seal.

 The above-mentioned sealed terminals have traditionally been coated on the inner and outer end wall of the body, as well as on the parts of the glass insulator and the conductor pin, with an epoxy resin coating. which improves the dielectric properties of the terminal and thus enables it to be applied

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 higher voltage without the risk of power outages. A coating that has been widely used in the industry is Morton Red Epoxy Coating, # 17-4001. Morton material # 17-4001 gave satisfactory performance on both the inner and outer surfaces of the waterproof terminal wall.

Another approach to coating the terminals was to use the Morton Red Epoxy # 17-4001 on the inside of the wall of the waterproof terminal, and a silicon rubber molded on the outside of the wall of the waterproof terminal.

While such an approach yields an acceptable product, coating the terminal with two different materials adds several steps to the manufacturing process, introduces production constraints, and therefore significantly increases the cost of the sealed terminal.

 The approach of covering the inner and outer wall of the terminal with a coating of two different material compositions, has emerged because the performance requirements for the inside and outside of the sealed terminal used in a hermetic compressor , are relatively different. Good chemical resistance is a major requirement for the inner wall of the waterproof terminal. The internal environment of a hermetic compressor typically contains refrigerants such as R12, R22, R134a, or the like. More specifically, the lining of the sealed terminal must not produce precipitate formation in the capillary tube of the compressor.

For the outer side of the terminal, the coating must provide improved electrical, thermal and mechanical characteristics. Of course, the coating formed on both sides of the terminal must have sufficient dielectric strength to allow the transmission of high voltages through the terminal.

 The present invention provides an improved electrical insulation coating for use in sealed compressor terminals. The coating of the present invention provides improved performance characteristics for both the outer side and the side

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 inside the waterproof terminal. The PEK material used to cover the terminal of the present invention is a known dielectric and has been used for a wide variety of applications. However, its use with a sealed compressor terminal to achieve an increase in distinct performance characteristics for both sides of a sealed compressor terminal, has been unknown until now.

 In one embodiment, the present invention consists of a sealed terminal of the type used to pass an electric current through a hermetic compressor housing. The terminal comprises a metal body for forming a seal with an opening formed in the hermetic compressor housing. The body of the terminal has an inner surface to face inwards in the compressor housing, and an outer surface to be turned outwardly of the compressor housing. A number of lead pins pass through an opening formed in the terminal body and are intended to conduct electricity through the terminal to pass it into the compressor housing. Each pin is hermetically sealed in the opening and electrically isolated from the terminal body. A poly (oxy-1,4-phenylenoxy-1,4-phenylenecarbonyl-1-4-phenylene) (PEEK) coating is adhered to the terminal and partially covers the inner and outer surfaces of the terminal body.

 According to other features of the invention: the opening is in the form of a one-piece collar starting from the body, an insulator disposed in the opening and surrounding the conductor pin provides the hermetic seal in the aperture and the electrical insulation of the pin relative to the body, this insulator having surfaces exposed with respect to the body, and the PEEK coating being adhered to these exposed surfaces so as to cover, - the PEEK coating covers the outer exposed surfaces of the collar and the insulator, as well as a part of

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 intermediate of the conductor pin, said intermediate portion extending outwardly from the opening, starting from both the inner and outer surfaces.

 In a preferred embodiment, the sealed terminal described above comprises the PEEK coating covering an intermediate portion of the conductor pin that protrudes outside the opening of both the inner and outer surfaces. . A glass insulator is disposed in the opening and hermetically fixes the pin in the opening ensuring electrical isolation of this close relative to the terminal body. The glass insulator also has exposed surfaces that are coated with the PEEK material of the present invention.

 But it can also be envisaged that according to the invention: the PEEK coating comprises two separate coatings, the first of these coatings being disposed on the inside of the body, while the second of these coatings is disposed on an outer surface of the body each of the coatings contains an opening through which the conductor pin passes, these coatings being otherwise essentially continuous.

 Advantageously: the coating has a thickness of at least 0.0075 inches and not more than 0.06 inches, the coating has a substantially uniform thickness .

 The invention also relates to a hermetic compressor comprising a housing provided with a terminal opening, characterized by the sealed terminal mounted in the terminal opening and forming a hermetic seal in the terminal opening.

 The advantage of the present invention is that it creates a single material having improved performance characteristics for both the inner side and the outer side of the sealed terminal, while maintaining the required dielectric properties and other characteristics.

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 relevant aspects of an electrical insulation coating.

Thus, because the present invention uses only one material to coat both sides of the terminal, the manufacturing costs are significantly reduced compared to the application of two different coatings. However, at the same time, the performance characteristics are not compromised. Advantageously, the performance characteristics are effectively improved on both sides of the terminal.

 Another advantage of the present invention is that the PEEK coating of the present invention flexes when the terminal is deformed. For example, during the installation of the waterproof terminals, each terminal may sometimes deform slightly. Advantageously, the PEEK coating of the present invention has been found to be able to withstand this deformation.

 Another advantage of the present invention is that the PEEK coating has improved chemical resistance to refrigerants typically used in hermetic compressors. In particular, the PEEK material of the present invention does not produce large precipitation of solids within the compressor.

 Yet another advantage of the present invention is that it has a high continuous use temperature around 260 C (500 F), ie a PEEK coated terminal of the present invention. can be subjected, without losing its performance characteristics, to higher operating temperatures than the terminals provided with coatings according to the prior art. In addition, a high continuous operating temperature allows the coating to better withstand the high temperature at which the terminal is subjected during the welding operation used to mount the terminal in the compressor housing.

 Yet another advantage of the present invention is that its coating can be applied more easily than the coatings of the prior art. In particular, the PEEK coating of the present invention can be applied to a terminal at room temperature, as opposed to the coating.

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 epoxy resin that required heating the terminal and then cooling it. In addition, the PEEK material bonds well to coated materials in a sealed terminal, such as electroless nickel and electroplated nickel.

 The present invention will be described below in more detail with the aid of an embodiment shown in the accompanying drawings in which: - Figure 1 is a perspective view of a sealed terminal constructed according to the present invention, the view mainly representing the side of the terminal which extends inwardly of the compressor housing in which it is mounted; FIG. 2 is a perspective view of a sealed terminal constructed in accordance with the present invention, the view mainly showing the side of the terminal which extends outwardly of the compressor housing in which it is mounted; and FIG. 3 is a cross-sectional view of the terminal of FIGS. 1 and 2, the section being taken along the median section of the terminal and along one of the conductor pins.

 Referring now to the drawings, these generally show a sealed compressor terminal constructed in accordance with the present invention and including a metal body 12 having an end wall 14 and a peripheral side wall 16 starting from this and ending with an outward flared flange 18.

A number of openings 20 pass through the end wall 14, and a collar 22 surrounding each opening 20 is formed integrally with the end wall 14 starting inwardly therefrom, although, in many cases, the collar 22 may extend outwardly, that is to say in the direction opposite to that of the wall 16. A conductor pin, represented generally at 24, passes through each opening and is sealed and sealed to terminal 10 by means of a molten isolator 26 within the limits of the opening

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 The insulator 26, which surrounds the pin 24, is typically made of glass and electrically insulates the pin 24 from the collar 22 and the end wall 14. Optionally, the pin 24 may consist of a very good electrically conductive inner core 28, and an outer core 30, as shown in FIG. 3, to improve the electrical conductivity across the terminal 10.

The portions of the lead pins 24 that extend outside terminal 10 include terminal tabs 32 attached thereto for ease of connection to electrical wires (not shown).

 As shown in the figures, and in particular in FIG. 3, the terminal 10 comprises two coatings 34, 36 of poly (oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1-4-phenylene) (PEEK) bonded thereto respectively on the inner surface and the outer surface of the end wall 14. Thus, it can be seen that the PEEK material partially overlaps the inner surface and the outer surface of the body of the terminal. PEEK is a member of the polyaryletherketone family and consists of a linear aromatic thermoplastic material that has a good balance of high temperature mechanical properties, chemical resistance and ease of processing, making it particularly well suited for hermetic compressor of the present invention. The PEEK material is manufactured and marketed by Victrex USA Inc., 601 Willowbrook Lane, West Chester, PA, 19382.

 As shown in FIGS. 1 and 3, the inner liner 34 covers the inner surface of the end wall 14, the exposed surfaces of the collar 22 and the exposed surface of the glass insulator 26. As shown in FIG. PEEK coatings 34 and 36 cover the intermediate portion 38 of the pin 24 which extends inwardly and outwardly from the end wall 14.

Although the thickness of the PEEK coating of the present invention may vary, it has been found that a thickness in the range of 0.19 to 0.51 mm (0.0075 to 0.020 inches) gives satisfactory performance. A thickness of

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 About 1.52 mm (0.060 inches) may be used if the PEEK coating is applied by injection molding.

 The PEEK coating of the present invention can be applied to the waterproof terminal in a variety of ways. Two methods of application use a fluidized bed, the. first of these methods consisting of an electrostatic application. In this process, the room temperature room is placed in a fixture attached to an electrical ground and placed on the fluidized bed. Dry air fluidizes the powder in the bed and creates a cloud of charged powder. The entire terminal, except pin contact areas and body ground points, is covered by the coating after applying a voltage of 0 to 80 kilovolts for 0 to 60 seconds. Vibration and alternating voltage or on / off voltage are used as required. The workpiece can then be cured by induction heating, thermal heating, or other heating methods after the excess coating material has been removed.

 Alternatively, instead of using the electrostatic application described above, a heated terminal is immersed in the fluidized powder bed, after which the PEEK material melts and amalgams into a continuous uniform coating on the unmasked portions from the terminal. The terminal is then removed and placed in a curing oven for final treatment. No electric charge is used in this process.

 The PEEK coating can be applied to the terminal by injection molding in which the PEEK material is heated and melted under pressure and then injected into a mold which holds the terminal. The piece is then turned and deburred. Because PEEK has a high viscosity, larger tapholes and larger valves are required to minimize pressure losses. The thickness of the PEEK for injection molding should be in the range of 1 to 1.52 mm (0.040 to 0.060 inches). The PEEK material and the plastic powder can be pressed to obtain a preformed sheet which is then placed on

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 the terminal and heated. Heat is applied as needed to ensure complete melting of the preformed material.

 Instead of using a fluidized bed, the part can be exposed in a chamber in which powder is released and in which the grounded terminal removes the coating by electrostatic attraction. Sprayers and other variants can be used. Finally, the PEEK material can be mixed with a solvent that dilutes and dissolves the material. The solution containing the PEEK is then placed on the terminal and, after drying, only the PEEK remains.

It can thus be noted that the PEEK coating of the present invention can be applied by a wide variety of processes, which allows for better control of production costs.

 Twelve materials were initially selected by the author of the present invention as candidates for an improved electrical insulation coating. Some of these initially sorted materials included Meldin 3000E, manufactured by Furon Dixon, and Morton Gray Nylon No.

76-7002. Table A below gives the list of twelve materials initially selected as possible candidates.

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Table A

<Tb>
<tb> Name <SEP> of the <SEP> product
<tb> Description <SEP> General <SEP> Company <SEP> Specific <SEP> Others
<tb> PK
<tb> Shell <SEP> Carilon <SEP> DP-P-1000
<tb> Polyketone <SEP> aliphatic
<tb> PEKK
<tb> (Ketone <SEP> of <SEP> polyether
<tb> Dupont <SEP> Declar
<tb> resin <SEP> of <SEP> ketone <SEP> thermoplastic)
<tb> PEEK
<tb>(SEP> Ketone SEP> polyether <SEP> Vitrex <SEP> Peek <SEP> 150 <SEP> PF
<tb> ether)
<tb> Polyamides <SEP> Dupont <SEP> AB <SEP> CITE <SEP> HP
<tb> Polyamides <SEP> Morton <SEP> Gray <SEP> Nylon <SEP> 76-7002
<tb> Poly (amide-imides) <SEP> Amoco <SEP> Al-10 <SEP> Polymer
<tb><SEP> Copolymer of <SEP> Polyolefin <SEP> of <SEP> Copolymer <SEP> of <SEP> Mitsui <SEP> TPX <SEP> White
<tb> pentene <SEP> of <SEP> methyl
<tb> Teflon <SEP> ETFE <SEP> with <SEP> epi <SEP> Teflon <SEP> ETFE
<tb> Dupont <SEP> Green
<tb> chlorohybrine <SEP> (epoxide) <SEP> (532-6004)
<tb> Teflon <SEP> PFA <SEP> Tetrafluo- <SEP> Dispersion <SEP> Teflon
<tb> Du- <SEP> Coating
<tb> roethylene / with <SEP> ether <SEP> from <SEP> P-532-5010 <SEP> or <SEP> 5012
<tb> bridge / Boyd <SEP> higher
<tb> vinyl <SEP> fluoride / dispersion <SEP> (Boyd <SEP> 9800) <SEP> ~~~~
<tb> Du- <SEP> VM <SEP> 7799
<tb> PTFE // Dispersion <SEP> Primer
<tb> Bridge / Boyd <SEP> (Boyd <SEP> 856-200)
<tb> 17-4001 <SEP> Red <SEP> Corvel
<tb> Epoxy <SEP> charged <SEP> of <SEP> Glass <SEP> Morton
<tb> powder
<tb> Polyimides <SEP> Furon <SEP> 3000E
<Tb>

After the initial sorting of the twelve materials listed in Table A above, only PEEK and 3M5388 manufactured by 3M, Minneapolis, Minnesota, remained viable candidates for an improved coating. As noted below, PEEK and 3M5388 were evaluated against the Morton Red Corvel 17-4001 material of the prior art. While 3M material was suitable for certain performance characteristics, only PEEK material was rated for all performance requirements.

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required maneuvers. In fact, when considering overall performance, the PEEK material scored remarkably (and unexpectedly) as considerably better than any other candidate material, as shown in Table I.

<Tb>
<Tb>

Table <SEP> I <SEP> ~~~~
<tb> Art <SEP> previous
<tb>########## 3 <SEP> M <SEP> 5388
<tb> Property <SEP> Victrex <SEP> PEEK <SEP> Morton <SEP> Red <SEP> Epoxy
<tb> Epoxy
<tb> 17-4001
<tb> Temperature
<tb> of use
<tb> 500 <SEP> 266 <SEP> 311
<tb> continue, F
<tb> (UL <SEP> 746B)
<tb> Lengthening <SEP> to
<tb> the <SEP> rupture <SEP> 20-50 <SEP> 1-2 <SEP> 5-10
<tb>% (ASTM <SEP> D882) <SEP> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~
<tb> Resistance <SEP> ame <SEP> Resistance <SEP> acceptTest <SEP> from <SEP> defrosted <SEP> to <SEP> crack <SEP> table <SEP> to <SEP> cracking
<tb> peeling / peeling <SEP>
<tb> Rigidity <SEP> di-
<tb> electric
<tb> 500 <SEP> @ <SEP> 2 <SEP> millet <SEP> 800 <SEP> @ <SEP> 6 <SEP> millet <SEP> 1100 <SEP> @ <SEP> 12 <SEP> millet
<tb> volts / millet
<tb> (ASTM <SEP> D <SEP> 149) <SEP> ~~~~
<tb> Absorption
<tb> water <SEP> in <SEP> weight <SEP> 0.5 <SEP> 0.3 <SEP> Good
<tb>% <SEP> (ASTM <SEP> D <SEP> 570) <SEP> ~~~~~
<tb> Extractable / <SEP> Point of <SEP> Enhanced <SEP> Acceptable <SEP> Enhanced
<tb> flocculation <SEP> ~~~ <SEP> ~~~
<Tb>
I. Temperature of continuous use
The continuous use temperature can be considered as the maximum temperature below which the material maintains a given characteristic for a reasonable period of time, this characteristic being in this case the dielectric strength. So, he is

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 It is desirable to have operating temperatures in continuous use as high as possible to avoid an electrical failure. Continuous use temperature tests were performed according to UL 746B. As shown in Table I, Morton Red Epoxy 17-4001 has a continuous use temperature of 130 C (266 F) which is considered acceptable for use in compressor components. The 3M 5388 material gives a slight improvement over the Morton material with a continuous use temperature of 155 C (311 F). In contrast, the PEEK material of the present invention has a continuous use temperature of 260 C (500 F), i.e., about twice the epoxy material of the prior art.

II. Elongation at break
Some compressor manufacturers mounting the terminals of the present invention, subject the terminals to deformation during the installation process. However, during this installation, the coating must flex or stretch with deformation of the terminal body. The Percentage Elongation at Break measures these characteristics and has been tested according to ASTM D882. ASTM D882 covers the determination of the tensile properties of plastics in the form of thin sheets comprising films less than 1 mm (40 mils). A test machine includes a set of pliers for holding the test specimen between a fixed member and a movable member of the machine. The percentage elongation at break is calculated by dividing the elongation of the specimen at the time of rupture, by the initial caliber length of the specimen, and multiplying by 100. As shown in Table I, the Morton Red Epoxy of the prior art can elongate 1-2% before breaking, while the PEEK material of the present invention can elongate by 20-50% before breaking. The 3M product provided a slight improvement over the Morton Red Epoxy.

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III. Deformation test
The coated terminals were placed in a closed chamber and subjected to pressures in the area of 13.8.106 Pa (2000 psi) which are large enough to deform the terminal to the point that the conductor pins touch each other. inner side of the terminal. As shown in Table I, the PEEK material of the present invention showed improved resistance to cracking and peeling compared to Morton Red Epoxy. The 3M material was not subjected to the deformation test, but was expected to operate in proportion to its elongation at break performance.

IV. Extractable test / flocculation point
The internal environment of a hermetic compressor typically contains refrigerants such as R12, R22, R34A and the like. The inner liner of the sealed terminal must be resistant to such refrigerants so that solids do not precipitate on the inner components of the compressor. A flocculation point test was performed on the candidate materials to determine their compatibility in the indoor environment of a hermetic compressor. Specimens weighing about 0.5 grams were cut from sample materials and placed in large glass tubes, one specimen per tube, and dried for 24 hours using heat and vacuum.

Three (3) ml of oil plus 1 ml of refrigerant was added to the tubes which were then sealed.

The oil and refrigerant combinations used were as follows: (a) Witco 3GS + R12 mineral oil (b) Zerol 150 + R22 synthetic alkylate (c) Sontex 200LT + R22 white oil (d) Emery polyol ester oil 2927A + R-134a
Normally, sealed tubes should be heat aged for 14 days at 150 C (302 F). However, the maximum continuous operating temperature for the Morton Red Corvel 17-4001 epoxy is 130 C

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 (266 F); as a result, the tubes were in fact heat aged for 14 days at 125 C (275 F).

After heat aging, the tubes were inspected visually. If the tubes contained flocculation at room temperature, no further testing was performed. If the oil in the tubes was clear at room temperature, flocculation point tests were performed using 1 ml of oil from the sealed tube plus 9 ml of refrigerant. The oil and refrigerant combinations used in the flocculation point tests were as follows: (a) Witco 3GS + R12 (b) Zerol 150 + R12 (c) Sontex 200LT + R12 (d) Emery 2927A + R-134a
R22 was not used in flocculation point tests because R22 and oil often have to separate into two layers, so-called phase separation, at temperatures above the flocculation point. If the phase separation temperature is higher than the flocculation point, then the flocculation point can not be determined. To avoid this problem, R12 is used instead of R22. Table II contains the results of visual observations and flocculation point tests.

 Sealed tube tests, followed by flocculation point tests, were used to determine the chemical compatibility of the three materials with the interior environment of a hermetic compressor. On the basis of the test results, PEEK has a higher chemical compatibility than Morton epoxide.

 As indicated more specifically in Table II below, the PEEK material of the present invention provides better performance than the Morton Red epoxy and 3M 5388 materials.

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<Tb>

Table <SEP> II
<tb> Result <SEP> of <SEP> tests <SEP> of extractables / point <SEP> of <SEP> flocculation
<tb> Identifica- <SEP> Oil <SEP> Information <SEP> of <SEP> sealed <SEP> tube <SEP> Information <SEP> of <SEP><SEP> point of <SEP> flocculation
<SEP><SEP> Refrigeration <SEP> Aspect <SEP> After <SEP> Heating <SEP> Refrigeration <SEP> Comments
<tb> material <SEP> rant <SEP> rant
<tb> Victrex <SEP> PEEK <SEP> Witco <SEP> 3 <SEP> GS <SEP> R12 <SEP> Clear <SEP> R12 <SEP> Ni <SEP> Veil <SEP> and <SEP> Flocculation <SEP > to <SEP> -50 F
<tb> 150 <SEP> PF
<tb> Zerol <SEP> 150 <SE> R22 <SEP> Clear <SEP> i <SEP> R12 <SEP> Ni <SEP> veil <SEP> and <SEP> flocculation <SEP> to <SEP> - 50 F
<tb> Sontex <SEP> 200 <SEP> LT <SE> R22 <SEP> Clear <SEP> R12 <SEP> Ni <SEP> Veil <SEP> and <SEP> Flocculation <SEP> to <SEP> - 50 F
<tb> Emery <SEP> 2927A <SEQ> R-134a <SEP> Clear <SEP> R-134a <SEP> Veil <SEP> formed <SEP> to <SEP> -45F, <SEP> not <SEP> from <SEP> flocculation <SEP> to
<tb> -50 F
<tb> 3M <SEQ> 5388 <SEP> Witco <SEP> 3 <SEP> GS <SEP> R12 <SEP> Clear <SEP> R12 <SEP> Ni <SEP> Veil <SEP> and <SEP> Flocculation <SEP > to <SEP> -50 F
<tb> Epoxy
<tb> Zerol <SEP> 150 <SE> R22 <SEP> Clear <SEP> R12 <SEP> Neither <SEP>SEP> nor <SEP> flocculation <SEP> to <SEP> -50 F
<tb> Sontex <SEP> 200 <SEP> LT <SE> R22 <SEP> Clear <SEP> R12 <SEP> Sail <SEP> formed <SEP> to <SEP> -45 F, <SEP> not <SEP> from <SEP> flocculation <SEP> to
<tb> -50 F
<tb> @
<Tb>
<tb> Emery <SEP> 2927A <SEP> R-134a <SEP> clear <SEP> R-134a <SEP><SEP> Veil formed <SEP> to <SEP> -45 F, <SEP> not <SEP> from <SEP> flocculation <SEP> to
<tb> @ <SEP> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <SEP> -50 F
<tb> Morton <SEP> Red <SEP> Witco <SEP> 3 <SEP> GS <SEP> R12 <SEP> Became <SEP> slightly <SEP> veiled <SEP> below <SEP> --- <SEP > Tests <SEP> of <SEP> point <SEP> of <SEP> flocculation <SEP> no <SEP> performed
<tb> Corvel <SEP> 17- <SEP> of <SEP> 125 F <SEP> after <SEP> several <SEP> days <SEP> of
<tb> 4001 <SEP> Epoxy, <SEP> depot, <SEP> a <SEP> certain <SEP> flocculation <SEP> se
<tb> Material <SEP> deposited <SEP> in <SEP> the <SEP> bottom <SEP> of the <SEP> sealed <SEP> tube
<tb> commonly <SEP> Zerol <SEP> 150 <SEP> R22 <SEP> --- <SEP><SEP><SEP><SEP><SEP><SEP> Flocculation <SEP> tests performed
<tb> used <SEP> with <SEP> As <SEP> above
<tb> Vitrus <SEP> Sontex <SEP> 200 <SEP> LT <SEP> R22 <SEP> --- <SEP><SEP><SEP> Tests <SEP><SEP><SEP> Flocculation No <SEP> performed
<tb> As <SEP> above
<tb> Emery <SEP> 2927A <SEP> R-134a <SEP> Became <SEP> veiled <SEP> below <SEP> of <SEP> 125 F <SEP> --- <SEP> Tests <SEP><SEP> point <SEP> of <SEP> flocculation <SEP> no <SEP> performed
<tb> with <SEP> a <SEP> flocculation <SEP> set <SEP> to <SEP> la
<tb> ambient temperature <SEP>. <SEP> After <SEP> filing <SEP> of
<tb> many <SEP> days, <SEP> it <SEP> y <SEP> had <SEP> one
<tb> large <SEP> quantity <SEP> of <SEP> flakes <SEP> in
<tb> the oil
<Tb>

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V. Dielectric stiffness test
While it is desirable to improve the mechanical and chemical properties of the terminal coating, it is also necessary to maintain the dielectric strength of the coating. The dielectric strength was measured according to the ASTM D149 standard which determines the dielectric breakdown voltage across the thickness of a test specimen. A fundamental requirement of the coating according to the present invention is that it supports the imposed tension when in use. As shown in Table 1, the dielectric strength of the PEEK material of the present invention is 500 volts for 0.0254 mm (1 mil) at a thickness of 0.05 mm (2 mils), which does not compromise the properties electrical insulation of the coating.

VI. Water absorption
Hermetic compressors can be subjected to high humidity environments. Thus, the water absorption in the insulating coating must be relatively low and the water present must not degrade the properties of the coating. This means that the moisture content of a plastic coating is closely related to properties such as electrical insulation resistance, dielectric losses, mechanical strength, appearance and dimensions. Water absorption was tested according to D570. As shown in Table I, the water absorption characteristic of the PEEK material of the present invention is 0.5% by weight, which is relatively low and therefore does not adversely affect the properties described above.

 In summary, the above test results showed that the PEEK coating of the present invention was the only candidate material that exhibited improved performance characteristics for the interior and exterior of a sealed terminal.

Claims (10)

 1) Waterproof terminal (10) of the type used to pass an electric current through a hermetic compressor housing, this terminal comprising a metal body (12) for forming a seal with a terminal opening formed in the housing of hermetic compressor, which body has an inner surface to be turned towards the inside of the compressor housing, and an outer surface to be turned outwardly of the compressor housing, at least one conductor pin (24) extending to through at least one corresponding aperture (20) formed in the body, and for conducting electricity through the terminal to pass it through the compressor housing, which lead pin is sealed in the opening (20) and electrically isolated from the body, characterized by a coating (34) of poly (oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1-4-phenylene) (PEEK) c ollé at the terminal, this coating covering at least partially the inner surface of the body. 2) waterproof terminal according to claim 1, characterized by a coating (36) of PEEK bonded to the terminal, this coating covering at least partially the outer surface of the body (12). 3) sealed terminal according to claim 1, characterized in that the opening (20) is formed as a single collar (22) from the body (12). 4) Waterproof terminal according to claim 3, characterized by an insulator (26) disposed in the opening (20) and surrounding the conductor pin (24), this isolator providing the hermetic seal in the opening and the insulation <Desc / Clms Page number 18>  electrical connection of the pin relative to the body (12), said insulator having surfaces exposed with respect to the body, and the PEEK coating being adhered to these exposed surfaces so as to cover them. 5) Waterproof terminal according to claim 4, characterized in that the PEEK coating covers the exposed outer surfaces of the collar (22) and the insulator (26), and an intermediate portion (38) of the conductor pin (24), this intermediate portion extending outwardly with respect to the opening (20), starting from both the inner surface and the outer surface. 6) Waterproof terminal according to claim 2, characterized in that the PEEK coating comprises two separate coatings (34, 36), the first (34) of these coatings being disposed on the inside of the body, while the second (34) ) of these coatings is disposed on an outer surface of the body. 7) waterproof terminal according to claim 6, characterized in that each of the coatings (34,36) contains an opening through which the conductor pin (24) passes, these coatings being otherwise essentially continuous. 8) waterproof terminal according to claim 1, characterized in that the coating (34) has a thickness of at least 0.19 mm (0.0075 inches) and not more than 1.52 mm (0.06 inches). 9) waterproof terminal according to claim 1, characterized in that the coating (34) has a substantially uniform thickness. <Desc / Clms Page number 19>  10) hermetic compressor comprising a housing provided with a terminal opening, characterized by the sealed terminal (10) according to claim 1, this terminal being mounted in the terminal opening and forming a hermetic seal in the opening of terminal.