WO2018050621A1

WO2018050621A1 - Compressor arrangement with integrated motor

Info

Publication number: WO2018050621A1
Application number: PCT/EP2017/072841
Authority: WO
Inventors: Youcef Ait Bouziad; Nicolas GANSHOF VAN DER MEERSCH; Thomas GABELLA
Original assignee: Nestec Sa
Priority date: 2016-09-15
Filing date: 2017-09-12
Publication date: 2018-03-22
Also published as: EP3513076A1; TW201814163A; CN109690086B; JP2019530823A; JP7159153B2; US20190203713A1; TWI743157B; CN109690086A

Abstract

The invention refers to a rotary compressor arrangement (100) comprising a stationary member (40) centered at a shaft axis (X) and a rotary member (90) rotating around the stationary member (40); the stationary member (40) and the rotary member (90) being inside a hermetically sealed inner volume within the compressor arrangement (100); the compressor arrangement (100) comprising a stator (210) with a winding arrangement (211) generating an electromagnetic force inside the stator (210), the stator (210) being arranged outside the hermetically sealed inner volume; the compressor arrangement (100) further comprising a plurality of magnets (221) directly attached to the rotary member (90) and facing the winding arrangement (211) in the stator (210) such that the rotary member (90) is entrained in rotation by a rotating electromagnetic field from the stator (210). The invention further refers to a cooling/refrigerating system comprising such a rotary compressor arrangement (100).

Description

Compressor arrangement with integrated motor

Field of the invention

The present invention is directed to a compressor arrangement comprising an integrated motor and, more specifically, to a rotary compressor arrangement of the vane type preferably used in a cooling or refrigerating system.

Background of the invention Currently, different types of compressors are used in cooling or refrigeration systems. Gas compressors are mechanical devices increasing the pressure of a gas by reducing its volume: by changing the state of the gas, its temperature is also changed. Therefore, when the gas passes through a condenser, it can be used as refrigerant in a refrigeration compressor.

For home applications, vane rotary compressors are commonly used as refrigeration compressors thanks to their reduced size. Typically, a vane rotary compressor comprises a circular rotor rotating inside of a larger circular cavity configured by the inner walls of the compressor housing. The centers of the rotor and of the cavity are offset, causing eccentricity. Vanes are arranged in the rotor and typically slide into and out of the rotor and are tensioned to seal on the inner walls of the cavity, in order to create vane chambers where the working fluid, typically a refrigerant gas, is compressed. During the suction part of the cycle, the refrigerant gas enters through an inlet port into a compression chamber where the volume is decreased by the eccentric motion of the rotor and the compressed fluid is then discharged through an outlet port.

While small sized vane rotary compressors are advantageous, leaking of refrigerant through the surfaces of the inner walls of the compressor housing is disadvantageous. This is why these compressors also use lubricating oil, having two main functions: one is to lubricate the moving parts, and the second one is to seal the clearances between the moving parts, which minimizes gas leakage that can adversely affect the efficiency of the compressor.

There exist different types of refrigeration compressors, varying depending on their configuration. Typically, refrigeration compressors can be open, semi-hermetic or hermetic. In hermetically sealed compressors, the compressor and its driving motor are coupled to a same shaft and are enclosed in a rigid hermetic casing. This type of hermetically sealed compressors are air tight and ensure no leakage of the working fluid to the outside. They are typically used in domestic refrigerators at home, in freezers or in air conditioners, for example. Semi-hermetic compressors also comprise inside a casing the compressor and its driving motor; however, this casing can be opened in order to access both the motor and the compressor itself in case of reparations being needed. On the other hand, open compressors are configured with no encasing of the compressor or the motor, so they are not leak proof and are susceptible to leak, relying on shaft seals, which need to be lubricated, to prevent leakage of working fluid and to maintain internal pressure.

One of the main advantages of a hermetic compressor is that it is configured as a single unit so it can be easily transported, thanks to its compactness. Moreover, it is less noisy and its installation is very easy. However, this compressor is typically not intended to be repaired so, when a problem arises, it is the whole unit which is replaced by a new one.

Semi-hermetic compressors are easier to repair compared to hermetic compressors, as they are accessible. However, certain leakages take place causing a certain loss of performance of the compressor.

In both hermetic and semi-hermetic compressors, the electronincs and wiring inside the casing are subjected to very high temperatures as they are arranged inside this hermetical encasing, which makes these types of compressors costly. Also, an eventual burnout of the windings can contaminate the whole system.

On the other hand, in open configurations, the compressor and the motor are easily accessible to be repaired in case of failure, the maintenance being cheap and easy. The motor outside of the hermetic chamber allows more variety in the motor selection and the use of cheaper motor types as they work at ambient conditions. The disadvantages of such configuration are that these compressor types are noisy, not compact and a certain gas leakage exists at the motor/chamber connection, which causes a loss of its performance. Moreover, lubricating oil is needed in the shaft seals so that they maintain their sealing properties. It would therefore be desirable to provide a compressor having the advantages of the open, hermetic and semi-hermetic compressors, avoiding at the same time their disadvantages.

It is known in the state of the art, for example in document EP 2307734 B1 , a rotary compressor arrangement having a rotating shaft where the motor structure is integrated inside the compressor arrangement. The whole structure is encased by an external housing hermetically sealing inside both the motor and the compressor, therefore constituting a hermetic compressor. This structure is compact but presents the disadvantage of the high temperatures reached in the electronic components inside, which cannot be properly refrigerated.

The compressor arrangement according to the present invention provides a compact, hermetic, yet silent and cost effective solution: the compression chamber is in a sealed internal volume; the electronic parts are outside and work at ambient conditions, and there is no direct physical connection between them, so any leakage is prevented.

Object and summary of the invention

According to a first aspect, the invention relates to a rotary compressor arrangement 100 comprising a stationary member 40 centered at a shaft axis X and a rotary member 90 rotating around the stationary member 40; the stationary member 40 and the rotary member 90 are inside a hermetically sealed inner volume within the compressor arrangement 100; the compressor arrangement 100 comprises a stator 210 with a winding arrangement 21 1 generating an electromagnetic force inside the stator 210, the stator 210 being arranged outside the hermetically sealed inner volume. The compressor arrangement of the invention further comprises a plurality of magnets 221 directly attached to the rotary member 90 and facing the winding arrangement 21 1 in the stator 210 such that the rotary member 90 is entrained in rotation by a rotating electromagnetic field from the stator 210. According to a preferred embodiment, the rotary compressor arrangement 100 of the invention further comprises a rolling member 10 eccentrically arranged with respect to the stationary member 40 such that a chamber is created between them; the arrangement 100 further comprising at least one satellite element 50 entrained in rotation by the rotary member 90; the at least one satellite element 50 orbiting at an offset axis Y and entraining in rotation the rolling member 10 and ensuring a contact between the stationary member 40 and the rolling member 10. Preferably, the rotary compressor arrangement of the invention further comprises an upper plate and a lower plate arranged to close in height in a tight manner at least one compression chamber 1 10 created between the stationary member 40 and the rolling member 10. Typically, the rotary compressor arrangement further comprises at least one segment element arranged between the upper and/or lower plates to allow a tight sealing of at least one compression chamber 1 10 and the movement of the rolling member 10. The at least one segment element 80 preferably comprises a low friction material.

In the rotary compressor arrangement of the invention, preferably at least a pair of satellite elements 50, 50' is arranged in height in the rotary member (90) in such a way that the magnets 221 are located between them. Typically, in the rotary compressor arrangement of the invention, the rotary member 90 is configured as a cylinder, the magnets 221 being directly attached in an external diametric circumference of it.

Typically, the satellite elements are mounted over bearings 300, preferably ball bearings.

In the rotary compressor arrangement of the invention, the stator 210 typically comprises a laminated magnetic core embedded in a resin material, the stator 210 being an integral part of the motor housing 230.

According to a preferred embodiment, the distance separating the winding arrangement 21 1 and the magnets 221 in the rotary compressor arrangement of the invention is as small as possible typically smaller than around 1 mm. The rotary compressor arrangement of the invention preferably further comprises at least one sealing piston 30 slidable within the stationary member 40 during rotation of the rolling member 10 creating at least one compression chamber 1 10 whose volume is decreased by rotation of the rolling member 10 so that a compressible fluid, preferably a refrigerant gas, is compressed before being discharged.

Typically, in the rotary compressor arrangement of the invention, lubricating oil is also provided together with the compressible fluid, compatible with it.

According to a second aspect, the invention refers to a cooling/refrigerating system comprising a rotary compressor arrangement 100 as the one previously described.

Brief description of the drawings

Further features, advantages and objects of the present invention will become apparent for a skilled person when reading the following detailed description of embodiments of the present invention, when taken in conjunction with the figures of the enclosed drawings.

Fig. 1 shows a representative view of the main components in a compressor arrangement with integrated motor according to the present invention.

Fig. 2 shows an external view of the compressor arrangement with integrated motor according to the present invention, as shown in Figure 1 . Fig. 3 shows a representative view of the stator of the motor and the magnets of the motor in a compressor arrangement with integrated motor according to the present invention.

Fig. 4 shows a representative view of the arrangement of the stator and windings and the rotary element in a compressor arrangement with integrated motor according to the present invention. Fig. 5 shows a sectional view of a compressor arrangement with integrated motor according to the present invention.

Fig. 6 shows a top view of the compressor arrangement with integrated motor according to the present invention.

Figs. 7a-b-c show exploded views of the external configuration, the rotary element comprising magnets and the stator comprising windings, respectively, in a compressor arrangement with integrated motor according to the present invention.

Figs. 8a-b-c-d show exploded views of the external configuration, the rotary element comprising magnets, the rolling element, vane and stationary body, and the stator comprising windings, respectively, in a compressor arrangement with integrated motor according to the present invention.

Detailed description of exemplary embodiments As shown in Figure 6 for example, the present invention relates to a vane rotary compressor arrangement, called in what follows rotary compressor arrangement 100 or simply rotary compressor 100. The rotary compressor 100 of the invention is preferably used in cooling or refrigerating systems, and the working fluid is typically any compressible gas, preferably a refrigerant gas or a mixture comprising a refrigerant gas.

The rotary compressor 100 comprises an inlet 130 through which the working fluid enters the compressor and an outlet 140 through which this fluid, once compressed, exits the mentioned compressor.

In a preferred embodiment of the invention, as it can be seen for example in Figure 8c, the compressor further comprises a rolling member 10 inside of which a stationary body 40 is arranged centered by a shaft axis X. The compressor also comprises a vane or sealing piston 30 which can slide into a slot 31 in order to contact the internal walls of the rolling member 10 and create a tight compression chamber where fluid will be compressed, as it will be further explained in more detail. As shown in Figure 8c, the stationary body 40 is arranged eccentrically inside the rolling member 10. Referring back to Figure 6, the inlet 130 and the outlet 140 for the working fluid are arranged in the stationary body 40, and are preferably arranged in the vicinity of the sealing piston 30. The arrangement of the invention is made in such a way that the shaft (and shaft axis X) and the stationary body 40 are one single piece within the rotary compressor 100 and are static. However, it is the rolling member 10 which rotates around the body 40, in fact which rolls over the external surface of the stationary body 40 entrained in rotation by means of at least one satellite element 50, as it will be explained further.

The sealing piston 30 is slidable within the slot 31 arranged in the body 40: pressure is maintained in this slot 31 to make the sealing piston 30 contact the inner wall of the rolling member 10 during the whole rolling of the rolling member 10 around the stationary body 40. For this to happen there exists a tensioning device inside the slot 31 exerting pressure over the sealing piston 30 so that it contacts the inner wall of the rolling member 10: any kind of tensioning device providing such functionality can be used, typically a spring, though a pneumatic device is also possible. In the arrangement of the present invention, as shown in Figure 6, the sealing piston 30 creates a compression chamber 1 10 of a variable volume. More than one sealing piston can be used in different embodiments of the invention, therefore creating more than one compression chamber.

In the rotary compressor arrangement of the invention, the referential system is actually inverted: the body 40 is stationary and it is the rolling member 10 which Is made to roll over it by a pressure exerted by the at least one satellite element 50 when rotating over it.

The arrangement of the invention also comprises at least one satellite element 50 mounted on a rotary member 90: by the rotation of this rotary member 90, the satellite element 50 is pushed over the rolling member 10 and rolls around it, pushing it towards the stationary body 40. Therefore, there exists a contact (typically, when the stationary body 40 and the rolling member 10 are cylindrically shaped, there exists a longitudinal contact line) between the rolling member 10 and the body 40, all the time while the rotary member rotates around the rolling member 10. It is also evident that this contact is aligned with the location of the satellite element 50. By the sealing piston 30 contacting the inner walls of the rolling member 10, a tight compression chamber 1 10 is created having variable volume (decreasing with time) where the working fluid is compressed before being discharged.

The satellite element is arranged offset from the axis X, at an axis Y as shown for example in Figure 5, and is made to orbit around the stationary body 40. The satellite element 50 contacts the external wall of the rolling member 10 under certain pressure or force (i.e. the distance between the axis X and Y is such that this force is exerted and maintained during the whole orbiting of the satellite element): as explained before, this contact of the satellite element 50 and the external wall of the rolling member 10 under pressure makes that the satellite element 50 entrains in rotation (actually rolls over) the rolling member 10 over the stationary body 40, similar as in a gear arrangement.

When looking for example at Figures 7b or 8b, a pair of satellite elements 50 and 50' for example are arranged at a certain height, pressing over the external wall of the rolling member 10, aligned with an inner contact of the stationary body 40 and the rolling member 10. These Figures also represent for example another pair of satellite elements 50" and 50"', arranged in height and also pressing over the external wall of the rolling member 10: in this configuration, the contact of the inner walls of the rolling member 10 with the stationary body 40 in an intermediate point between the external contacts of the pairs of satellite elements 50, 50' and 50", 50"'.

The satellite elements are typically mounted over bearings 300, preferably ball bearings, as shown for example in Figures 1 or 4.

Typically, the compressor arrangement of the invention works with a refrigerant gas as working fluid, and oil is also entrained with the refrigerant in the compressor, in order to lubricate the moving parts and to seal the clearances or gaps between them. Oil is preferably introduced in the compressor by an oil pump (not shown) and there is also typically provided a device (not shown) to gather this oil and return it to the oil pump so that it is pumped once again together with the refrigerant. The lubricating oil may be any oil compatible with the refrigerant used as working fluid in the compressor. The refrigerant may be any suitable refrigerant that is effective in a given temperature range of interest.

Typically, the compressor arrangement of the invention also comprises an upper plate and a lower plate closing the upper and lower parts of the compressor, thus sealing the compression chamber 1 10 created together with the sealing piston 30. The distance between the two plates and the height of the body configuring the rolling member 10 must be precise in order to correctly seal and create the compression chamber 1 10, though a certain clearance adjustment or compensation is feasible acting on the satellite element(s). However, no other parts configuring the compressor arrangement of the invention are needed to be done with precise tolerances as it is the case in the known prior art, which makes this arrangement much easier to be manufactured and consequently less costly. Typically, at least one segment element is further arranged between the upper and/or lower plates to allow a tight sealing of the compression chamber 1 10 and at the same time allow the movement of the rolling member 10. This arrangement is done in such a way that lower friction in the movement of the rolling member 10 with respect to the stationary body 40 and the plates is allowed. Preferably, the material configuring the segment element is a low friction material, typically Teflon^®.

These low friction materials allow long life solutions typically in applications where the sliding action of parts is needed, still with low maintenance being required. The friction characteristics of a material are given typically by the coefficient of friction, which gives a value showing the force exerted by a surface made of such a material when an object moves across it, such that a relative motion exists between the two, the object and the surface. Typically, for Teflon, this coefficient of friction is comprised between 0.04 and 0.2. Low friction materials have a coefficient of friction below 0.4, more preferably below 0.3 and even more preferably below 0.2. The object of the invention is to integrate the driving motor structure into the arrangement of a rotary vane compressor itself. This motor integration according to the invention can be done in compressor arrangements having a fixed shaft axis (or stationary body 40 together with a shaft axis X) and an external rotating part (in this case, an external rotary member 90). In a preferred embodiment of the invention, the configuration of the compressor arrangement 100 comprises satellite elements mounted in the rotary member 90, pushing the rolling member 10 over the stationary body 40, as discussed. The windings 21 1 are mounted on an external stator 210, while magnets 221 are directly attached onto the external surface of the rotary member 90, directly facing these windings 21 1 , with no metallic element arranged in between. The distance between the magnets and the windings shall be free and as small as possible, typically below around 1 mm; otherwise the efficiency will drop drastically and would be impossible to rotate the rotor. When electrical current circulates through the windings 21 1 an electromagnetic force or field is generated inside the stator 210: these windings work as electromagnets and therefore have poles, the opposite poles of which are in the magnets 221 directly attached to the rotary member 90. The magnetic fields created between these poles are designed to orientate and create forces providing a torque in the rotary member 90 making it rotate.

It is evident that in classical rotary compressors such an arrangement for the windings and the magnets would not be possible because there is no external rotating element where the magnets could be attached and where they could face directly (without any metallic elements interposed) the windings in the rotor. The configuration of the present invention is particularly advantageous as it integrates the rotor of the compressor (rotating part of the compressor arrangement, the rotary member 90) with the rotor of the motor (i.e. where the permanent magnets are) in one single element, therefore providing a compact and hermetic solution. Moreover, the windings of the stator are arranged externally and can be advantageously refrigerated compared to hermetic solutions where they are inside a closed chamber. The chamber hermetically sealed in the arrangement 100 of the invention groups inside the body 40, the rolling member 10, the rotary element 90 and the magnets 221 , as shown for example in Figure 5. The stator 210 together with the windings 21 1 can be therefore arranged outside this hermetic chamber and can be easily refrigerated, as shown in any of Figures 1 or 2, for example. The stator 210 in the arrangement of the invention typically comprises a laminated magnetic core embedded in a resin, being configured as an integral part of the motor housing (the stator 210 constitutes the vertical part of the motor housing). The laminated magnetic core typically comprises a plurality of thin metallic sheets lying essentially parallel with the lines of flux, so the magnetic core is made equivalent to many individual magnetic circuits, each one receiving a small fraction of the magnetic flux, therefore highly restricting most of the flow of Eddy currents.

In general terms, the arrangement of the invention proposed the use of the rotary part of the compressor to be used as well as the rotor of the motor. This allows a direct driving of this rotary part, which highly reduces the number of parts and the noise. The final structure of the compressor arrangement is very solid and compact and is made able to withstand 20 bars of pressure remaining tight for the refrigerant gas used. Also by the use of the bearings over which the rotary part is mounted, the arrangement is made very compact. Also, heat dissipation from the stator is improved as it is directly in contact with external air. The rigid structure of the magnetic circuit integrated in the compressor arrangement therefore contributes to the mechanical resistance of the motor housing.

Referring now to the Figures attached, Figure 1 shows the arrangement of the stationary body 40 eccentrically surrounded by the rolling member 10, which is made to roll over the external walls of the body 40 by means of the rotary member 90 mounted over bearings 300. Magnets 221 are directly attached onto the outer wall of the rotary member 90, facing corresponding windings 21 1 in the stator 210. The typical laminated structure of the stator is not represented in this Figure, though.

Figure 2 shows the whole compressor arrangement 100 seen from the outside, as a full compact structure with the motor housing 230 outside, showing the stator 210 sheltering inside the windings 21 1 . Figure 3 shows where these windings are located inside the stator 210 and how they face (floating view) the magnets 221 .

Figure 4 shows where the satellite elements would be arranged within the compressor, mounted on the rotary member 90.

Figure 5 shows a sectional view of the compressor arrangement according to a preferred embodiment of the invention, showing the hermetic chamber grouping inside the magnets 221 , the rotary member 90, the rolling member 10 and the stationary body 40. The stator 210 with the windings 21 1 is arranged outside this hermetic chamber.

Figure 6 shows the structure of a rotary vane compressor with a fluid inlet 130 and a fluid outlet 140 for the fluid once it has been compressed. It is shown the sealing piston 30 which can slide into a slot 31 in order to contact the internal walls of the rolling member 10 and create a tight compression chamber 1 10 where fluid is compressed before being discharged through the outlet 140. Two satellite elements are shown, 50 and 50" which push the rolling member 10 over the stationary body 40 to vary the volume of the chamber 1 10. It can be seen here how the contact of the inner walls of the rolling member 10 with the outer walls of the stationary body 40 occurs at an intermediate angular location between the external contacts of the satellite elements 50 and 50" with the rolling member 10. Figures 7a, 7b and 7c show the motor housing 230 with the stator 210 (Figure 7a); the rotary member 90 with the magnets 221 attached outside and how a pair of satellite elements 50, 50' and another pair of satellite elements 50", 50"' are arranged in height in this member 90 to push and roll over the rolling member 10 (Figure 7b); the stator configuration 210 with the windings 21 1 , which will be face the magnets 221 (Figure 7c).

Figures 8a, 8b, 8c and 8d show the motor housing 230 with the stator 210 (Figure 8a); the rotary member 90 with the magnets 221 attached outside and how a pair of satellite elements 50, 50' and another pair of satellite elements 50", 50"' are arranged in height in this member 90 to push and roll over the rolling member 10 and between which the magnets 221 are arranged (Figure 8b); the rolling member 10 eccentrically arranged over the stationary body 30 and the sealing piston 30 contacting the inner wall of it (Figure 8c); the stator configuration 210 with the windings 21 1 , which will be face the magnets 221 (Figure 8d).

Although the present invention has been described with reference to preferred embodiments thereof, many modifications and alternations may be made by a person having ordinary skill in the art without departing from the scope of this invention which is defined by the appended claims.

Claims

Rotary compressor arrangement (100) comprising a stationary member (40) centered at a shaft axis (X) and a rotary member (90) rotating around the stationary member (40);

the stationary member (40) and the rotary member (90) being inside a hermetically sealed inner volume within the compressor arrangement (100); the compressor arrangement (100) comprising a stator (210) with a winding arrangement (21 1 ) generating an electromagnetic force inside the stator (210), the stator (210) being arranged outside the hermetically sealed inner volume; the compressor arrangement (100) further comprising a plurality of magnets (221 ) directly attached to the rotary member (90) and facing the winding arrangement (21 1 ) in the stator (210) such that the rotary member (90) is entrained in rotation by a rotating electromagnetic field from the stator (210).

Rotary compressor arrangement (100) according to claim 1 further comprising a rolling member (10) eccentrically arranged with respect to the stationary member (40) such that a chamber is created between them;

the arrangement (100) further comprising at least one satellite element (50) entrained in rotation by the rotary member (90);

the at least one satellite element (50) orbiting at an offset axis (Y) and entraining in rotation the rolling member (10) and ensuring a contact between the stationary member (40) and the rolling member (10).

Rotary compressor arrangement (100) according to any of the previous claims further comprising an upper plate and a lower plate arranged to close in height in a tight manner at least one compression chamber (1 10) created between the stationary member (40) and the rolling member (10).

Rotary compressor arrangement (100) according to claim 3 further comprising at least one segment element arranged between the upper and/or lower plates to allow a tight sealing of at least one compression chamber (1 10) and the movement of the rolling member (10).

Rotary compressor arrangement (100) according to any of claims 2-4 wherein at least a pair of satellite elements (50, 50') is arranged in height in the rotary member (90) in such a way that the magnets (221 ) are located between them.

6. Rotary compressor arrangement (100) according to claim 5 wherein the rotary member (90) is configured as a cylinder, the magnets (221 ) being directly attached in an external diametric circumference of it.

7. Rotary compressor arrangement (100) according to any of claims 2-6 wherein the satellite elements are mounted over bearings (300), preferably ball bearings. 8. Rotary compressor arrangement (100) according to any of the previous claims wherein the stator (210) comprises a laminated magnetic core embedded in a resin material, the stator (210) being an integral part of the motor housing (230). 9. Rotary compressor arrangement (100) according to any of the previous claims wherein the distance separating the winding arrangement (21 1 ) and the magnets (221 ) is as small as possible, typically smaller than around 1 mm.

10. Rotary compressor arrangement (100) according to any of the previous claims further comprising at least one sealing piston (30) slidable within the stationary member (40) during rotation of the rolling member (10) creating at least one compression chamber (1 10) whose volume is decreased by rotation of the rolling member (10) so that a compressible fluid, preferably a refrigerant gas, is compressed before being discharged.

1 1 . Rotary compressor arrangement (100) according to claim 10 wherein lubricating oil is also provided together with the compressible fluid, compatible with it. 12. Cooling/Refrigerating system comprising a rotary compressor arrangement

(100) according to any of claims 1 -1 1 .