WO2009137901A2

WO2009137901A2 - Motor, gas compressor and agitation element

Info

Publication number: WO2009137901A2
Application number: PCT/BR2009/000127
Authority: WO
Inventors: Fabian Fagotti
Original assignee: Whirlpool S.A.
Priority date: 2008-05-13
Filing date: 2009-05-13
Publication date: 2009-11-19
Also published as: CN102089958A; EP2283562A2; BRPI0801482A2; US20110142694A1; KR20110027664A; JP2011520419A; WO2009137901A3

Abstract

The present invention refers to a motor having a constructive arrangement capable of cooling the environment in which said motor is disposed. In a preferred embodiment, said electric motor (101) has a stator (103) disposed inside a rotor (102). This rotor (102) comprises an outer surface (104) that has a first end portion (105) provided with a central hub (108) concentrically surrounded by a radial sector (109) disposed substantially inclined in relation to a perpendicular plane to the central axis of the rotor (102). Said radial sector (109) is convergent upon the central hub (108) and comprises at least a radial opening (110) capable of providing the dispersion of gas contained in an internal environment of the rotor (102). In another preferred embodiment, the rotor (102) comprises at least an agitation element (111) associated to the outer surface (104). This agitation element (111), which is also the object of the present invention, is capable of providing a movement of gas when the rotor (102) rotates. The present invention also refers to a gas compressor (100) having an electric motor (101) mentioned above according to at least one of its preferred embodiments.

Description

Title: "MOTOR, GAS COMPRESSOR AND AGITATION ELEMENT".

The present invention refers to a motor having a constructive arrangement capable of cooling the environment in which it is disposed, as well as its internal components. The present invention also refers to a gas compressor having an electric motor capable of cooling the elements, parts and components disposed inside of said compressor.

The present invention also refers to an agitation element, for use in an electric motor, capable of cooling the environment in which it is disposed, as well as its internal components. Description of the State of the Art

The efficiency of a gas compressor depends on its thermal profile. In this sense, the constructive arrangements of compressors capable of lowering the temperature of the gas (sucked out) to be compressed present a better volumetric efficiency, that is, a greater mass pumped per cycle. Various constructive arrangements have been developed so as to keep the temperature of the gas to be compressed relatively low. For example, North American document US 4,960,368 discloses a compressor having a suction muffler made of a low heat conductivity material. Document US 4,755,108 describes a compressor in which the pipe conducting the gas from the relatively hot walls of the suction muffler is insulated from the other elements, parts and components of said compressor.

Documents US 6,325,600 and US 6,155,800 disclose compressors in which the connection between the parts and the suction muffler or even the compression chamber is made directly with a minimum or no mixture of relatively cold gas from the suction with the relatively hot gas of the internal environment of the compressor.

Another important aspect to be considered is the need to keep the inner temperature at a low level, because there is a maximum limit for the temperature supportable by each component, according to the material used. These limits are particularly important for the electric motor, which is why various kinds of constructive arrangements are provided that are capable of increasing the circulation of gas in the internal environment of the compressor, increasing the heat transfer rate of the motor to the external environment of the compressor. For example, the North American document US 5,464,332 discloses a compressor having a motor, whose rotor is disposed inside the stator, and one end of the crankshaft of the rotor has a fan capable of providing circulation or movement of the gas present in the internal environment of the compressor. Since the motor of the compressor disclosed in this North American document has a stator disposed inside the rotor, the excessive heating of the motor becomes ever more critical, by virtue of the existence of a smaller area of heat exchange between the stator and the internal environment. Additionally, due to physical limitations resulting from this constructive arrangement, the fan can only be disposed directly at just one end of the crankshaft, restricting the movement of gas to just one region nearby, so compromising the efficiency of the cooling of the internal environment of the compressor. Additionally, this fan, apparently, does not permit the cooling of the internal rotor, and the movement of the gas is restricted to the outer portion of the motor (e.g. stator), to the extent of limiting the efficiency and performance of the motor.

Therefore, no satisfactory and efficient solution is yet known for cooling the internal environment of compressors having rotors disposed outside the stators, which has good reliability and performance, and that is still capable of preventing overheating of the compressor motor. Objectives of the Invention

A first objective of the present invention consists of providing a motor capable of permitting efficient and suitable cooling of the environment where it is located, by way of a solution that presents a simplified and low cost implementation/maintenance. A second objective of the present invention consists of providing a gas compressor capable of permitting an increase in the efficiency of the circulation and/or agitation of the gas contained in its internal environment, increasing the heat exchange of the elements, parts and components of the compressor with its housing, so as to lower the temperature thereof.

A third objective of the present invention consists of providing a constructive element, for use in a rotor of an electric motor, capable of permitting an efficient and suitable cooling of the environment wherein said motor is disposed. Brief Description of the Invention

A first way of achieving the first objective of the present invention is by providing an electric motor having a stator disposed inside a rotor. Said rotor comprises an outer surface having a first end portion provided with a central hub concentrically surrounded by a radial sector. Said radial sector has a substantially inclined profile in relation to a perpendicular plane to the central axis of the rotor. This profile of the radial sector is convergent upon the central hub. Said radial sector comprises at least a radial opening capable of providing a dispersion of gas contained in an internal environment of the rotor.

A second way of achieving the first objective of the present invention is by providing an electric motor having a stator disposed inside the rotor. Said rotor comprises an outer surface having: a first end portion having a central hub; a second end portion disposed opposite to the first end portion; and an intermediary portion disposed between the first end portion and the second end portion. Said rotor comprises at least an agitation element associated to the outer surface. Said agitation element is capable of providing a movement of gas when the rotor rotates. A third way of achieving the first objective of the present invention is by providing an electric motor having a stator disposed inside the rotor. Said rotor comprises an outer surface having: a first end portion having a central hub concentrically surrounded by a radial sector; a second end portion disposed opposite to the first end portion; and an intermediary portion disposed between the first end portion and the second end portion. Said radial sector has a substantially inclined profile in relation to a perpendicular plane to the central axis of the rotor. This profile of the radial sector is convergent upon the central hub. Said radial sector comprises at least a radial opening capable of providing the dispersion of gas contained in the internal environment of the rotor. Said rotor comprises at least an agitation element associated to the second end portion and to the intermediary portion. Said agitation element is capable of moving the gas when the rotor rotates.

A first way of achieving the second objective of the present invention is by providing a gas compressor that comprises an electric motor operatively associated to a cylinder capable of compressing the gas coming from an environment outside the compressor. Said cylinder and the electric motor are comprised by a housing. Said electric motor is in accordance with the first way of achieving the first objective of the present invention mentioned above.

A second way of achieving the second objective of the present invention is by providing a gas compressor that comprises an electric motor operatively associated to a cylinder capable of compressing the gas coming from an environment outside the compressor. Said cylinder and the electric motor are comprised by a housing. Said electric motor is in accordance with the second way of achieving the first objective of the present invention mentioned above.

A third way of achieving the second objective of the present invention is by providing a gas compressor that comprises an electric motor operatively associated to a cylinder capable of compressing the gas coming from a means outside the compressor. Said cylinder and the electric motor are comprised by a housing. Said electric motor is in accordance with the third way of achieving the first objective of the present invention mentioned above.

The third objective of the present invention is achieved by providing an agitation element for use in a rotor of an electric motor. Said rotor comprises an outer surface having: a first end portion having a central hub; a second end portion opposite to the first end portion; and an intermediary portion being disposed between the first end portion and the second end portion. Said agitation element is associable to the first end portion, to the second end portion and/or to the intermediary portion. Said agitation element is capable of providing a movement of gas when the rotor rotates. Brief Description of the Drawings

The present invention will now be described in further detail, with reference to the appended drawings, wherein:

Figure 1 - depicts a cut view of a compressor, object of the present invention, which comprises a first embodiment of an electric motor, also the object of the present invention;

Figure 2 - depicts a frontal view of the rotor of the electric motor illustrated in Figure 1 ;

Figure 3 - depicts an top view of the rotor of the electric motor illustrated in figure 1 ; Figure 4 - depicts a perspective view of the rotor of a first variation of a second embodiment of the electric motor, the object of the present invention;

Figure 5 - depicts an top view of the rotor of the motor illustrated in figure 4; Figure 6 - depicts a perspective view of the rotor of a second variation of the second embodiment of the electric motor, the object of the invention;

Figure 7 - depicts an down view of the rotor of the motor illustrated in figure 6; Figure 8 - depicts a frontal view of the rotor of the motor illustrated in figure 7; and

Figure 9 - depicts a perspective view of the rotor of a third variation of the second embodiment of the electric motor, the object of the present invention. Detailed Description of the Drawings and the Invention First Preferred Embodiment

Figure 1 illustrates a sectional view of a gas compressor 100, the object of the present invention, preferably for use in cooling equipment such as, for example, domestic, commercial or industrial refrigerators or freezers. Optionally, the gas compressor 100 can also be used for other applications that require the use of compressed gas. The gas compressor 100 comprises an electric motor 101 , also the object of the present invention, having a stator 103 capable of permitting the rotation of a rotor 102. As can be noted in figure 1 , the stator 103 is disposed inside the rotor 102. This arrangement enables a greater potential for agitating the gas contained in the internal environment of the compressor 100, which benefits its heat exchange with the external environment, so as to lower its inner temperature. The external environment and the internal environment of the compressor are separated by a housing 115 of the compressor 100.

The rotor 102 is associated to a rotary crankshaft 116 which in turn is operatively associated to a cylinder 114, where the gas is compressed. The rotary crankshaft 116 is also associated to an outer surface 104 comprised by the rotor 102. Accordingly, the rotary crankshaft 116 rotates around the central axis of the rotor 102 solidarily to the outer surface 104. Said outer surface 104, made of magnetic and/or electric material, has a first end portion 105 provided with a central hub 108 capable of receiving the rotary crankshaft 116. The central hub 108 is concentrically surrounded by a radial sector 109 having a substantially inclined profile (slanted or sloped) in relation to a perpendicular plane to the central axis of the rotor 102. Hence, this radial sector 109, preferably a circular sector, is disposed along the radii of the central hub 108, so as to encircle said central hub 108 externally. The radial sector 109 also comprises at least a radial opening 110 capable of providing the dispersion of gas contained in the internal environment of the rotor 102. As can be noted in figure 2, the profile of the radial sector 109 converges towards the central hub 108, in such a way that this constructive arrangement allows enhanced directioning, pumping and dispersion of the gas, enabling an optimal circulation and efficient cooling with a minimum viscous loss. So, the radial openings 110 are arranged so as to have a profile that favors the circulation of the gas, and the optimum of this profile depends on the work fluid and the rotation of the motor. Preferably, the radial sector 109 comprises a plurality of radial openings 110, as illustrated in figure 3, so as to permit enhanced cooling. The geometric shape of the radial openings 110 is substantially triangular. However, other shapes can also be adopted provided that they are capable of adequately dispersing the gas present inside the rotor 102, so as to cool the elements, parts and components of the motor 101 and the compressor 100. Second Preferred Embodiment

In this second preferred embodiment, illustrated by figures 4 to 9, the outer surface 104 of the rotor 102 comprises at least an agitation element 111 , also the object of the present invention, capable of providing a movement/pumping of gas when the rotor 102 rotates.

Preferably, the electric motor 101 comprises a plurality of agitation elements 111 disposed radially on the outer surface 104 of the rotor 102, so as to provide a better movement/pumping of gas present around and/or inside the motor 101 and a more efficient circulation of gas in the internal environment of the compressor 100.

Also preferably, the agitation element 111 has a substantially fan or blade-shape structure to establish a flow of gas in the gap between the rotor 102 and the stator 103, inside the motor 101. This fan or blade arrangement may have a helicoidal, sloping, straight, curved profile or any other suitable constructive arrangement for the application. Therefore, any shapes and profiles can be used provided that they are suitable and capable of moving the gas present around the electric motor 101. The quantity and optimal geometric shape of the agitating elements 111 essentially depend on the work fluid and the rotation of the rotor 102.

Therefore, the agitation element 111 disclosed in this invention, besides moving/pumping the gas present around the motor 101 , allows the flow of gas inside the motor 101 , so as to achieve an optimal cooling performance, cooling the elements, parts and components of the motor 101 and the compressor 100.

The agitation element 111 can be fixably associated on or removably associated to the outer surface 104 of the rotor 102. In the fixed solution, the agitation element 111 can be soldered, glued or produced entirely in a single part, to the outer surface 104. In the removable solution, the agitation element 111 can be associated by mechanical means such as screws and/or rivets or even by interference fit. In other words, the agitation elements 111 can be implemented in the electric motor 101 based on stamping of the very blades that form the magnetic material part of the rotor 102 or based on an additional part made of metal, magnetic or electric material or any kind of polymer, mounted on the body of the rotor 102, for example, by interference, gluing or soldering. In a first variation of this second preferred embodiment, shown in figures 4 and 5, the agitation element 111 is disposed in the second end portion 107 of the outer surface 104 of the rotor 102. A second end portion 107 is disposed opposite to the first end portion 105, in relation to the central axis of the rotor 102. Preferably, the agitation element 111 is disposed in a first wall

112 of the second end portion 107. This first wall 112 is disposed substantially orthogonally in relation to the central axis of the electric motor 101. Optionally, the agitation element 111 can be disposed on a second wall 113 of the second end portion 107. This second wall 113 is disposed substantially parallel in relation to the central axis of the electric motor 101.

Also optionally, the agitation elements 111 can be disposed both on the first wall 112 as on the second wall 113 on the same rotor 102.

In a second variation of this second preferred embodiment, shown in figures 6 to 8, the agitation element 111 is disposed in an intermediary portion 106 of the outer surface 104 of the rotor 102. This intermediary portion 106, which preferably constitutes the electrical part of the rotor 102, is disposed between the first end portion 105 and the second end portion 107.

In a third variation of this second preferred embodiment, illustrated in figure 9, the agitation elements 111 are disposed on the intermediary portion 106 and on the second end portion 107, providing an even larger movement of gas. Particularly, figure 9 illustrates an arrangement with high agitation of gas, obtained with a construction that uses the first and second preferred embodiments concomitantly.

In said construction, each agitation element 111 has a longitudinal extension that comprises the entire distance delimited by the two ends (lower and upper) of the intermediary portion 106, providing a maximum extension for gas agitation. This agitation element 111 has a profile substantially blade shaped arranged in the form of a wedge or shell, which permits an optimal drag of the gas present around the rotor 102. In tests carried out in a compressor having a 120 W Ashrae LBP capacity, constructed in accordance with this third variation, a reduction of around 5 degrees Celsius was noted, using an R600A-type refrigerant. Said reduction increases the efficiency of the compressor by about 2%.

It is important to note that in figures 2 to 9, the first preferred embodiment of this invention was used jointly with the second preferred embodiment, to provide an enhanced movement/circulation of gas. Therefore, besides the radial sector 109 having radial openings 110, an additional movement of gas is achieved by constructing the agitation elements 111 on the body of the rotor 102. In another possible variation of this second preferred embodiment, the agitation element 111 is disposed on the first end portion 105 of the outer surface 104 of the rotor 102.

In any one of the variations mentioned above, the quantity, arrangement and physical disposition of the agitation elements 111 along the outer surface 104 can vary in accordance with the application desired.

Thus, the agitation element 111 is associable to the first end portion 105, to the second end portion 107 and/or to the intermediary portion 106.

Obviously, this is not a compulsory condition, and it is perfectly feasible to implement just the agitation elements 111 (second preferred embodiment), suppressing the use of the radial sector 109 having radial openings 110 (first preferred embodiment) or vice-versa.

Having described examples of preferred embodiments, it should be understood that the scope of the present invention encompasses other possible variations, and is only limited by the content of the appended claims, wherein potential equivalents are included.

Claims

1. Electric motor (101) having a stator (103) disposed inside a rotor (102), the rotor (102) comprising an outer surface (104) having a first end portion (105) provided with a central hub (108) concentrically surrounded by a radial sector (109), the motor (101 ) being characterized in that the radial sector (109) has a substantially inclined profile in relation to a perpendicular plane to the central axis of the rotor (102), the profile of the radial sector (109) being convergent upon the central hub (108), the radial sector (109) comprising at least a radial opening (110) capable of providing the dispersion of gas contained in an internal environment of the rotor (102).

2. Electric motor according to claim 1 , characterized in that the radial sector (109) comprises a plurality of radial openings (110).

3. Electric motor according to claim 1 , characterized in that the rotor (102) comprises at least an agitation element (111) associated to the outer surface (104), the agitation element (111) being capable of providing a movement of gas when the rotor (102) rotates.

4. Electric motor according to claim 3, characterized by comprising a plurality of agitation elements (111 ) disposed radially on the outer surface (104) of the rotor (102).

5. Electric motor according to claim 3, characterized in that the agitation element (111) is fixably associated on the outer surface (104) of the rotor (102).

6. Electric motor according to claim 3, characterized in that the agitation element (111) is removably associated on the outer surface (104) of the rotor (102).

7. Electric motor according to claim 3, characterized in that the agitation element (111) is disposed in the second end portion (107) of the outer surface (104) of the rotor (102), the second end portion (107) being disposed opposite to the first end portion (105).

8. Electric motor according to claim 7, characterized in that the agitation element (111 ) is disposed on a first wall (112) of the second end portion (107), the first wall (112) being disposed substantially orthogonally in relation to the central axis of the electric motor (101).

9. Electric motor according to claim 7, characterized in that the agitation element (111 ) is disposed on a second wall (113) of the second end portion (107), the second wall (113) being disposed substantially parallel in relation to the central axis of the electric motor (101 ).

10. Electric motor according to claim 3, characterized in that the agitation element (111) is disposed in an intermediary portion (106) of the outer surface (104) of the rotor (102), the intermediary portion (106) being disposed between the first end portion (105) and the second end portion (107).

11. Electric motor according to claim 3, characterized in that the agitation element (111) is disposed on the first end portion (105) of the outer surface (104) of the rotor (102).

12. Electric motor according to claim 3, characterized in that the agitation element (111) has a substantially fan or blade-like structure.

13. Gas compressor (100) comprising an electric motor (101 ) operatively associated to a cylinder (114) capable of compressing the gas coming from an environment outside the compressor (100), the cylinder (114) and the electric motor (101 ) being comprised by a housing (115), the electric motor (101 ) having a stator (103) disposed inside a rotor (102), the rotor (102) comprising an outer surface (104) having a first end portion (105) provided with a central hub (108) concentrically surrounded by a radial sector (109), the compressor being characterized in that the radial sector (109) has a substantially inclined profile in relation to a perpendicular plane to the central axis of the rotor (102), the profile of the radial sector (109) being convergent upon central hub (108), the radial sector (109) comprising at least a radial opening (110) capable of providing the dispersion of gas contained in the internal environment of the rotor (102).

14. Agitation element (111 ) for use in a rotor (102) of an electric motor (101 ), the rotor (102) comprising an outer surface (104) having:

- a first end portion (105) having a central hub (108);

- a second end portion (107) opposite to the first end portion (105); and

- an intermediary portion (106) being disposed between the first end portion (105) and the second end portion (107), the agitation element (111 ) being characterized in that it is associable to the first end portion (105), to the second end portion (107) and/or to the intermediary portion (106), the agitation element (11 1 ) being capable of providing a movement of gas when the rotor (102) rotates.

15. Agitation element (111 ) according to claim 14, characterized in that it is fixably associated to the first end portion (105), to the second end portion (107) and/or to the intermediary portion (106) of the outer surface (104) of the rotor (102).

16. Agitation element (111) according to claim 14, characterized in that it is removably associated to the first end portion (105), to the second end portion (107) and/or to the intermediary portion (106) of the outer surface (104) of the rotor (102).

17. Agitation element (111 ) according to claim 14, characterized by presenting a substantially fan or blade-like structure.

18. Electric motor (101 ) having a stator (103) disposed inside the rotor (102), the rotor (102) comprising an outer surface (104) having: - a first end portion (105) having a central hub (108);

- a second end portion (107) disposed opposite to the first end portion (105); and

- an intermediary portion (106) disposed between the first end portion (105) and the second end portion (107), the electric motor (101) being characterized in that the rotor (102) comprises at least an agitation element (111 ) associated to the outer surface (104), the agitation element (1 11 ) being capable of providing a movement of gas when the rotor (102) rotates.

19. Motor according to claim 18, characterized in that the agitation element (111 ) is removably associated to the outer surface (104) of the rotor (102).

20. Motor according to claim 18, characterized in that the agitation element (111 ) is fixably associated to the outer surface (104) of the rotor (102).

21. Motor according to claim 18, characterized in that the rotor (102) comprises a plurality of agitation elements (111 ).

22. Motor according to claim 18, characterized in that the agitation element (111 ) has a substantially fan or blade-like structure.

23. Motor according to claim 18, characterized in that the agitation element (111) is associated to the first end portion (105) of the outer surface (104) of the rotor (102).

24. Motor according to claim 18, characterized in that the agitation element (111) is associated to the second end portion (107) of the outer surface (104) of the rotor (102).

25. Motor according to claim 18, characterized in that the agitation element (111) is associated to the intermediary portion (106) of the outer surface (104) of the rotor (102).

26. Gas compressor (100) comprising an electric motor (101 ) operatively associated to a cylinder (114) capable of compressing the gas coming from an environment outside the gas compressor (100), the cylinder (114) and the electric motor (101 ) being comprised by a housing (115), the electric motor (101 ) having a stator (103) disposed inside the rotor (102), the rotor (102) comprising an outer surface (104) having:

- a first end portion (105) having a central hub (108);

- an intermediary portion (106) disposed between the first end portion (105) and the second end portion (107), the gas compressor (100) being characterized in that the rotor (102) comprises at least an agitation element (111 ) associated to the outer surface (104), the agitation element (111 ) being capable of providing a movement of gas when the rotor (102) rotates.

27. Electric motor (101) having a stator (103) disposed inside the rotor (102), the rotor (102) comprising an outer surface (104) having:

- a first end portion (105) having a central hub (108) concentrically surrounded by a radial sector (109);

- an intermediary portion (106) disposed between the first end portion (105) and the second end portion (107), the electric motor (101 ) being characterized in that:

- the radial sector (109) has a substantially inclined profile in relation to a perpendicular plane to the central axis of the rotor (102), the profile of the radial sector (109) being convergent upon the central hub (108), the radial sector (109) comprising at least a radial opening (110) capable of providing the dispersion of gas contained in the internal environment of the rotor (102); and

- the rotor (102) comprises at least an agitation element (1 11 ) associated to the second end portion (107) and to the intermediary portion (106), the agitation element (111 ) being capable of providing a movement of gas when the rotor (102) rotates.

28. Gas compressor (100) comprising an electric motor (101 ) operatively associated to a cylinder (114) capable of compressing the gas coming from an environment outside the gas compressor (100), the cylinder (114) and the electric motor (101) being comprised by a housing (1 15), the electric motor (101 ) having a stator (103) disposed inside the rotor (102), the rotor (102) comprising an outer surface (104) having:

- a first end portion (105) having a central hub (108);

- an intermediary portion (106) disposed between the first end portion (105) and the second end portion (107), the gas compressor (100) being characterized in that:

- the rotor (102) comprises at least an agitation element (111 ) associated to the second end portion (107) and to the intermediary portion (106), the agitation element (111 ) being capable of providing a movement of gas when the rotor (102) rotates.