DE102011053144A1 - Motor driven compressor - Google Patents

Abstract

A motor-driven compressor has a housing with an inlet and an outlet, a compression mechanism provided in the housing for compressing coolant introduced into the housing through the inlet and for discharging compressed coolant from the housing through the outlet, an electric motor which is provided in the housing, and which has a rotor with a permanent magnet and a stator fixed to the housing, and a shaft that is rotated by the electric motor to drive the compression mechanism. The compressor also has a water separator in which water flowing with the coolant and / or the lubricating oil in the housing is collected.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a motor-driven compressor for use in a refrigeration system.

In engine-driven compressors for use in a refrigeration system such as a vehicle air conditioner, the electric motor for driving the compression mechanism is provided in the compressor housing which forms part of a refrigeration cycle by which refrigerant circulates together with lubricating oil and engine oil respectively. The electric motor is equipped with a permanent magnet, for example a ferrite magnet or rare-earth magnet. Such a permanent magnet is exposed to an environment in which the magnet may be in contact with the coolant and lubricating oil circulating through the cooling circuit.

For example, water may be present in the refrigeration circuit due to aging or loss of refrigerant and / or lubricating oil, and also depending on the environment in which the compressor is in use. Acid can also be produced in the presence of water from the coolant or lubricating oil. Any permanent magnet exposed to contact with circulating water or circulating acid in the coolant may age, deteriorate, or wear due to the associated chemical reaction. To solve such a problem, the Japanese Unexamined Patent Application Publication No. 2009-225636 to form a protective film on the surface of the permanent magnet of the electric motor of the motor-driven compressor to improve the corrosion resistance of the permanent magnet.

The use of such a protective film is effective for preventing the aging of the permanent magnet, but any damage to the protective film itself reduces its effectiveness. Therefore, irrespective of the presence of the protective film, the water contained in the refrigerating cycle and possibly causing the deterioration of the permanent magnet should preferably be removed as extensively as possible to make contact between the permanent magnet and the water or between the permanent magnet and prevent the acid caused by the water.

The present invention is directed to providing a motor-driven compressor which allows removal of water from the refrigeration cycle in which the compressor is incorporated, thereby preventing deterioration of the permanent magnet of the electric motor of the compressor.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a motor-driven compressor includes: a housing having an inlet and a drain, a compression mechanism provided in the housing for compressing refrigerant introduced into the housing through the inlet and discharging compressed air Coolant from the housing through the drain, an electric motor provided in the housing and having a rotor with a permanent magnet and a stator fixed to the housing, and a rotating shaft which is rotated by the electric motor to drive the compression mechanism. The compressor further includes a water trap in which water that flows with the coolant or lubricating oil in the housing collects.

Other aspects and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

1 Fig. 11 is a longitudinal sectional view of a motor-driven compressor according to a first embodiment of the present invention, showing a water separator and its associated passage of the compressor;

2 is a schematic representation of a vehicle air conditioning system having a cooling circuit in which the compressor according to 1 is involved;

3 is a view of a longitudinal section of a second embodiment of the motor-driven compressor;

4 Fig. 12 is a view of a longitudinal section of a third embodiment of the motor-driven compressor;

5 is an enlarged breakout view of the passage of the compressor of 4 ; and

6 is a cross-sectional view of the passage, as viewed in accordance with the arrow VI in 5 ,

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the first embodiment of the motor-driven compressor according to the present invention will be described with reference to FIGS 1 and 2 described. According to 1 has the motor-driven compressor, generally by the reference numeral 1 is characterized, a housing 10 , a compression mechanism 15 , a wave 21 , and an electric motor 2 on. It should be noted that the upper and the lower side, as in 1 You can see the top or bottom of the compressor 1 if this is installed on site, corresponds. The housing 10 has a feed 11 and a process 12 and takes in the compression mechanism 15 , the wave 21 and the electric motor 2 on. The compression mechanism 15 compresses that through the inlet 11 in the case 10 introduced coolant and leads the compressed coolant through the drain 12 out of the case 10 from. The electric motor 2 rotates the shaft 21 to the compression mechanism 15 drive.

The compression mechanism 15 has a fixed (fixed) gear 13 , which is fixed in the housing, and a movable gear 14 , opposite to the fixed (fixed) gear 13 is arranged. The fixed gear 13 and the movable gear 14 form compression spaces between themselves 150 from whose volume are variable. The movable gear 14 is with an eccentric pin 210 the wave 21 about a camp 216 and an eccentric bush 215 connected to an orbital motion in accordance with the rotation of the shaft 21 and thereby the volume of the compression chambers 150 to vary.

The electric motor 2 has a rotor 22 and a stator 23 , The rotor 22 has a central recess 221 on, through which the wave 21 is fixed. The wave 21 extends from the rotor 22 starting and is in the housing 10 on its opposite side over bearings 41 . 42 rotatably mounted. The stator 23 is over the case 10 around the rotor 22 stored around and has a coil 235 , If the coil 235 is energized with the permanent magnets 3 equipped rotor 22 rotates.

The rotor 22 is configured over a plurality of magnetic steel plates laminated together in a cylindrical shape. The rotor 22 has axially extending recesses 225 on, in which the permanent magnets 3 are inserted. In the present embodiment, the permanent magnet 3 by a known neodymium magnet or rare earth magnet having neodymium (Nd), iron (Fe) and boron (B) as main components.

The compressor 1 also has a below and separately from the housing 10 provided water separator 7 and a passage (channel) 75 on top of the inside of the water separator 7 and the inside of the case 10 combines. The passage 75 has a circular cross-section with an inner diameter of about 20 mm and a cross-sectional area of about 314 mm ² . The passage 75 is arranged such that the central axis of the passage 75 in the vertical direction of the compressor 1 is aligned. The water separator 7 has a capacity or volume that is large enough, the total possible free water 8th take.

In the present embodiment, the compressor 1 for a vehicle air conditioning system 5 in use, as in 2 is shown. The air conditioner 5 has a capacitor 51 , a tank 52 , a relaxation valve 53 and an evaporator 54 on. The compressor 1 , the capacitor 51 , The Tank 52 , the relaxation valve 53 and the evaporator 54 are connected in this order to a cooling circuit 55 the air conditioning 5 train. The opening of the expansion valve 53 is via a control / regulation 57 depending on the temperature of the coolant passing through a temperature sensor 56 is measured, the downstream of the evaporator 54 is arranged, adjusted.

The Tank 52 separates coolant into vapor and liquid and delivers only the liquid coolant to the expansion valve 53 , The Tank 52 also removed by an adsorber (not shown) in the tank 52 is provided, water contained in the coolant. The cooling circuit 55 or the motor-driven compressor 1 contains 2,3,3,3-tetrafluoro-1-propene (CF ₃ -CF = CH ₂ ) as a coolant and polyol ester as a lubricating oil. A non-metallic resin pipe or plastic pipe becomes in a section of the cooling circuit 55 used.

When the air conditioning 5 is in operation for a long time, can permeate through such a resin tube water and partly in the cooling circuit 55 penetration. Possible water in the cooling circuit 55 that the motor-driven compressor 1 includes, is present, tends to be at the bottom of the housing 10 of the compressor 1 to accumulate as free water when the compressor 1 stops.

As previously described, the compressor 1 the water separator 7 which is below and separate from the housing 10 is provided, the passage 75 the inside of the water separator 7 with the inside of the case 10 combines. This will be the bottom of the case 10 collected water through the passage 75 in the water separator 7 moved and as indicated by the reference numeral 8th indexed in it.

As the water separator 7 , which is below the case 10 is provided by the cooling circuit 55 in which during operation of the compressor 1 The coolant circulates, is separated, it prevents that in the water separator 7 collected water back into the housing 10 flows. This way, every time the compressor starts 1 stops any in the cooling circuit 55 contained water as the free water 8th in the water separator 7 collected, whereby the aging or deterioration of the permanent magnet 3 is prevented due to water.

3 shows the second embodiment of the motor-driven compressor according to the present invention. The second embodiment differs from the first embodiment in the structure of the passage, the housing 10 and the water separator 7 connects, off. As shown in the drawing, the passage is 76 of the second embodiment relative to the vertical direction of the compressor 1 inclined so that the central axis C of the passage 76 with the flow direction A of the coolant in the housing 10 forms an acute angle. Other elements or components are the same as those of the first embodiment.

The second embodiment, which has such a sloping passage 76 has further prevented that in the water separator 7 collected free water 8th in the case 10 flows back and also prevents that in the case 10 arranged coolant under the influence of the circulation of the coolant during operation of the compressor 1 in the water separator 7 flowing back. The second embodiment provides the advantages similar to those of the first embodiment.

4 . 5 and 6 show the third embodiment of the motor-driven compressor according to the present invention. The third embodiment deviates from the first embodiment in the structure of the housing 10 and the water separator 7 connecting passage. As in 4 the passage is shown 77 of the third embodiment with three employed plates 79 acting as an anti-reflux mechanism to prevent that in the water separator 7 collected water back into the housing 10 flows. As in 5 shown are the hired plates 79 on the inner surface of the passage 77 attached so that the distal ends or the distal ends 791 the corresponding inclined plates 79 downwards or to the water separator 7 are aligned. As in 6 showed the passage 77 in its axial view of such a shape that the circular cross section in sections through the straight end 791 the hired plate 79 is cut away.

In the third embodiment, this is in the housing 10 arranged free water along the corresponding staffed panels 79 in the water separator 7 emotional. The hired plates 79 Continue to prevent that in the water separator 7 collected free water 8th through the passage 77 back into the case 10 flows. The third embodiment also provides the advantages similar to those of the first embodiment.

In the foregoing embodiments, an agent containing at least one water adsorbent or acid neutralizer may be contained in the water separator 7 to be available. This modification allows it in the water separator 7 collected water to be adsorbed by the adsorbent and in the water separator 7 to be neutralized by the neutralizer collected acid and thus more to prevent aging or deterioration of the permanent magnet due to water or acid.

The water adsorbent should preferably be formed from a zeolite or boiling stone, from activated carbon, or from alumina Al ₂ O ₃ or silica gel. The adsorbent formed from one or more such materials has a good volume-specific adsorption and therefore requires in the water 7 whose capacity is limited, less space. Such an absorbent is generally known as a siccative or desiccant.

The acid neutralizer should preferably be at least one of calcium hydroxide, magnesium hydroxide, calcium carbonate or sodium carbonate because the neutralizer formed from one or more such materials is in the form of a solid and is stable over a long period of use.

In the above-described compressor, the passage should be like the passage 75 that the case 10 and the water separator 7 connects, preferably have a cross-sectional area that is large enough for the passage to be less affected by the surface tension of the free water, but small enough for the coolant, so that this smoothly in the housing 10 can flow. The cross-sectional area of the passage should preferably be in particular between 0.75 and 650 mm ² . The passage with a cross-sectional area less than 0.75 mm ² could cause blockage of the passage due to the surface tension of the free water and consequently the free water from flowing smoothly into the water trap 7 hold. The passage with a cross-sectional area greater than 650 mm ² could be the coolant flow in the housing 10 influence and also cause that in the water 7 collected water back into the housing 10 flows. Therefore, the diameter of the passage of a circular cross section should preferably be between 1 and 50 mm in order to keep the above-described interval of passage area of the passage.

The water separator 7 should be preferred from the housing 10 be solvable. This modification allows it in the water separator 7 For example, in a routine inspection, dispose of collected water by using the water separator 7 from the case 10 is solved. Such a releasable connection is formed via a plurality of known connection mechanisms.

From the point of view of magnetic properties, the rare earth magnet is for use as a permanent magnet 3 of the motor driven compressor more suitable than the ferrite magnet. However, on the other hand, since the rare earth magnet is more susceptible to corrosion than the ferrite magnet, corrosion causing water should preferably be fast in the water separator 7 to be collected from the compressor.

In the vehicle air conditioner 5 becomes part of the cooling circuit 55 a nonmetallic tube such as a resin tube / plastic tube is used to make the tube more flexible and improve the vibration damping property. The term "resin" or plastic is used here in a broad sense, including natural resin, synthetic resin, natural rubber and synthetic rubber. The non-metallic pipe such as the resin pipe tends to allow little water penetration. When such a non-metallic pipe is used for a long period of time under hot and humid conditions, water contained in the air can pass through the non-metallic pipe into the cooling circuit 55 penetration. Coolant and lubricating oil may be due to the entry of water into the cooling circuit 55 change their properties and thereby produce acid. Therefore, that should be in the case 10 occurring water prefers fast in the water separator 7 to be collected.

There is a general trend of preferring to use a refrigerant with less ozone layer influence than the refrigerant generally known as a chlorofluorohydrocarbon in a refrigeration system. As such a novel refrigerant having a molecular formula C ₃ H _m F _n and a double bond in the molecular structure, wherein m is an integer of 1 to 5, n is an integer of 1 to 5 and m + n = 6 has 2,3,3,3-tetrafluoro-1-propene (CF ₃ -CF = CH ₂ ) has attracted the attention of the industry. Such a coolant is referred to as HFO1234yf coolant type.

The HFO1234yf type refrigerant has the double bond and therefore is relatively susceptible to being decomposed in the presence of water. In the case where, for some reason, water is mixed with the refrigerant in the refrigerant circuit during the manufacturing process of the compressor or during market use, the refrigerant may be decomposed to produce hydrofluoric acid (HF). An acid such as hydrofluoric acid causes relatively premature corrosion of the permanent magnet. Therefore, should be in the vehicle air conditioner 5 , in which such type HFO1234yf coolant is in use, the water contained in the housing 10 occurs, preferably fast in the water separator 7 to be collected.

The above-described compressor is advantageous in the case where the housing 10 Contains lubricant or lubricating oil containing one or more of the substances polyol ester (POE), polyvinyl ether (PVE) or polyalkylene glycol (PAG). The penetration of water or acid into the cooling circuit 55 is also undesirable in the case where such a lubricating oil in the housing 10 For example, because polyol ester is hydrolyzed in the presence of water, producing organic carboxylic acid which, as in the case of hydrofluoric acid, can cause corrosion of the permanent magnet. So that should be in the case 10 existing water prefers fast in the water separator 7 to be collected.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2009-225636 [0003]

Claims (11)

A motor driven compressor comprising: a housing with an inlet and a drain; a compression mechanism provided in the housing for compressing coolant introduced into the housing through the inlet and discharging compressed coolant from the housing through the outlet; an electric motor provided in the housing and having a rotor with a permanent magnet and a stature fixed to the housing; and a rotating shaft driven by the electric motor to drive the compression mechanism marked by a water separator in which water flowing in the housing with coolant and lubricating oil is collected. The motor-driven compressor of claim 1, further comprising a passage connecting the interior of the housing and the water separator, the water separator being provided below or in the bottom / bottom of the housing. The motor-driven compressor of claim 2, wherein the passage has a cross-sectional area of 0.75 to 650 mm ² . The motor-driven compressor of claim 2 or 3, wherein the passage has an anti-reflux mechanism to prevent backflow of water collected in the water trap into the housing. The motor-driven compressor according to any one of claims 2 to 4, wherein the passage is inclined so that the center axis of the passage forms an acute angle with the flow direction of the coolant in the housing. The motor-driven compressor according to any one of claims 1 to 5, wherein the water separator is detachable from the housing The motor-driven compressor according to any one of claims 1 to 6, wherein an agent / additive containing a water adsorbent and / or an acid neutralizer is present in the water separator. The motor-driven compressor according to any one of claims 1 to 7, wherein the permanent magnet is a rare-earth magnet. The motor-driven compressor according to any one of claims 1 to 8, wherein the compressor is in use for a vehicle air conditioner having a refrigerant circuit formed in sections over a non-metallic pipe. The motor-driven compressor according to any one of claims 1 to 9, wherein the compressor is in use for a refrigeration system using a refrigerant having a molecular formula C ₃ H _m F _n and a double bond in the molecular structure, where m is an integer 1 to 5, n is an integer of 1 to 5 and m + n = 6, or in which a coolant mixture containing coolant is used. The motor-driven compressor according to any one of claims 1 to 10, wherein in the housing there is a lubricating oil containing polyol ester (POE) and / or polyvinyl ether (PVE) and / or polyalkylene glycol (PAG).

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