Motor protector unit and electric compressor

Abstract

This motor protector unit comprises a motor protector, a motor protector holder, and a connecting structure that connects and secures the motor protector and the motor protector holder. The motor protector includes: a metal hermetic container configured to be airtight and including a housing having an opening and an internal space, and a lid plate provided on the housing to cover the opening; two conductive terminal pins provided on the lid plate via an electrically insulating filler material, each pin having one end inserted into the hermetic container and the other end exposed on the outside of the hermetic container; and an opening / closing mechanism provided inside the hermetic container to open or close an electrical connection between the two conductive terminal pins. The motor protector holder includes: a covering part into which at least a part of the motor protector is fitted; and wing parts formed in the shape of plates extending out at right angles to the longitudinal direction of the conductive terminal pins.

Description

Motor protector unit and electric compressor

[0001] An embodiment of the present invention relates to a motor protector unit and an electric compressor.

[0002] Conventionally, electric compressors equipped with constant-speed motors are equipped with motor protectors to protect them from burning out in the event of an abnormality. The motor protector has a thermally responsive plate that operates in response to heat generated by the ambient temperature inside the compressor or the current flowing through the motor protector. The operation of this thermally responsive plate opens the circuit, cutting off current to all windings of the motor.

[0003] In contrast, for example, in inverter-driven electric compressors, the inverter's control unit detects open phases and abnormal currents, so no protective measures other than the control unit are required. However, without protective measures other than the control unit, if the control unit malfunctions due to a fault or incorrect wiring, it is impossible to prevent abnormal currents from flowing to the electric compressor. Therefore, even in inverter-driven electric compressors, there is a growing need for protective measures separate from the control unit to reliably protect the electric compressor from abnormal currents. To address this need, an external motor protector that does not require modifications to the electric compressor is being considered. However, external motor protectors have poor responsiveness to changes in the internal temperature of the compressor housing, such as winding temperature. Therefore, to ensure reliable overheating protection, an internal protector installed inside the compressor housing is preferred.

[0004] Japanese Patent Application Laid-Open No. 2004-44408

[0005] However, in a configuration in which the motor protector is installed inside the compression container, there is a problem in that the workability when attaching the motor protector to the motor is poor.

[0006] This embodiment has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a motor protector unit that can improve workability when attaching a motor protector to a motor using a motor protector holder, and an electric compressor equipped with this motor protector unit.

[0007] The motor protector unit of one embodiment comprises: a metal airtight container having an airtight structure including a housing with an opening and a space inside, and a cover plate attached to the housing and covering the opening; a motor protector having two conductive terminal pins attached to the cover plate via an electrically insulating filler, one end of which is inserted into the airtight container and the other end of which is exposed to the outside of the airtight container; and an opening / closing mechanism attached to the airtight container for opening and closing the electrical connection between the two conductive terminal pins; a motor protector holder having a cover portion into which at least a portion of the motor protector is fitted, and plate-shaped wing portions extending perpendicular to the longitudinal direction of the conductive terminal pins; and a connection structure for connecting and fixing the motor protector to the motor protector holder.

[0008] The electric compressor of this embodiment comprises a motor including a compression mechanism and windings, a compressor container that houses the compression mechanism and the motor, and the motor protector unit housed within the compressor container, with the motor protector connected to the windings on the neutral side of the motor.

[0009] 1 is a perspective view of an example of a motor protector unit according to an embodiment, showing the motor protector fitted into the holder from the upper front side; 2 is a perspective view of an example of a motor protector unit according to an embodiment, showing the motor protector fitted into the holder from the upper rear side; 3 is a perspective view of an example of a motor protector unit according to an embodiment, showing the motor protector fitted into the holder from the lower front side; 4 is a perspective view of an example of a motor protector unit according to an embodiment, showing the motor protector removed from the holder from the lower front side; 8 is a cross-sectional view showing an example of a motor protector unit according to an embodiment, showing a state in which windings are connected along line X9-X9 of FIG. 8; FIG. 9 is a cross-sectional view showing an example of a motor protector unit according to an embodiment, showing a state in which windings are connected along line X10-X10 of FIG. 8; FIG. 10 is a cross-sectional view showing an example of a motor protector unit according to an embodiment, showing a state in which windings are connected along line X11-X11 of FIG. 8;

[0010] A motor protector unit 1 according to one embodiment will be described below with reference to the drawings. The motor protector unit 1 includes a motor protector 2, a motor protector holder 3, and a connection structure 70. In the following description, the motor protector holder 3 may be simply referred to as the holder 3.

[0011] The motor protector 2 is suitable for motors, particularly three-phase motors, built into hermetic electric compressors used in air conditioners, for example. The motor protector 2 is connected to the neutral point of the three-phase motor when in use, for example. The holder 3 holds the motor protector 2 and attaches the motor protector 2 to the electric compressor. The motor protector unit 1 can be attached to the motor, for example, with the vertical direction shown in Figures 1 and 2 facing the direction of gravity. Note that the orientation in which the motor protector unit 1 is attached to the motor is not limited to the above. The motor protector unit 1 can also be attached to the motor in an orientation inverted upside down or rotated 90 degrees from the orientation shown in Figures 1 and 2.

[0012] An example of the motor protector 2 will be described below. Note that the motor protector employed in the motor protector unit 1 is not limited to the motor protector 2 described below. The motor protector 2 operates and opens the circuit when a predetermined abnormal current flows through the motor protector 2, causing it to heat up, or when the motor itself heats up due to some abnormality, causing the ambient temperature to rise to a predetermined temperature. When the motor protector 2 operates, it disconnects the neutral point of the three-phase motor and cuts off the power supply to all windings of the motor.

[0013] As shown in FIGS. 9 to 11 , the motor protector 2 includes an airtight container 10, two conductive terminal pins 20, and an opening / closing mechanism 30. The airtight container 10 forms the outer shell of the motor protector 2 and is airtight. As shown in FIGS. 4 , 5 , and 9 to 11 , the airtight container 10 includes a housing 11 and a cover plate 12. The housing 11 is made of, for example, metal and is formed in a dome shape with an open end and an internal space. The cover plate 12 is provided in a position that covers the opening of the housing 11. The cover plate 12 is, for example, a metal plate-like member and is formed in a shape that fits the opening of the housing 11. In this embodiment, the airtight container 10 is formed elongated along the surface direction of the cover plate 12. The cover plate 12 is fixed to the end of the opening side of the housing 11 by welding or the like around its entire periphery, thereby airtightly closing the opening of the housing 11.

[0014] The conductive terminal pins 20 are made of a conductive material such as metal and are formed, for example, in the shape of a cylindrical rod. Two conductive terminal pins 20 are each inserted through a pin hole 121 formed in the cover plate 12, and are attached to the cover plate 12 with one end inserted into the interior of the airtight container 10 and the other end exposed to the exterior of the airtight container 10. An electrically insulating filler 13 such as glass is provided between the inside of the pin hole 121 and the conductive terminal pins 20. The filler 13 can also be referred to as an insulating member. This allows the conductive terminal pins 20 to be fixed to the cover plate 12 in an airtight and electrically insulated state.

[0015] The conductive terminal pin 20 may have a structure including, for example, multiple layers with different properties. In this embodiment, the conductive terminal pin 20 has a two-layer structure. For example, as shown in FIGS. 8 and 9 , the conductive terminal pin 20 may be configured to include a core material 21 and an outer material 22. The core material 21 forms the center of the conductive terminal pin 20. The outer material 22 is provided on the outside of the core material 21 and forms the outer surface of the conductive terminal pin 20. The conductive terminal pin 20 has a core material 21 made of, for example, copper, which has high electrical conductivity, and an outer material 22 made of, for example, an iron-nickel alloy or ferritic stainless steel, which has higher rigidity than the copper core material 21.

[0016] The opening and closing mechanism 30 is for opening and closing the electrical connection between the two conductive terminal pins 20. The opening and closing mechanism 30 has the function of opening and closing the electrical connection between the two conductive terminal pins 20 when the ambient temperature inside the airtight container 10 reaches or exceeds a predetermined temperature. The opening and closing mechanism 30 has two fixed contacts 31, two movable contacts 32, a support 33, an elastic plate 34, and a thermally responsive plate 35. The opening and closing mechanism 30 is provided inside the airtight container 10. That is, the fixed contacts 31, the movable contact 32, the support 33, the elastic plate 34, and the thermally responsive plate 35 are all provided inside the airtight container 10.

[0017] The fixed contacts 31 are made of a conductive metal material, such as a clad material of a silver oxide alloy and copper or a copper alloy. The two fixed contacts 31 are provided inside the airtight container 10 and electrically connected to the conductive terminal pins 20. Each fixed contact 31 is fixed to the end of the conductive terminal pin 20 inside the airtight container 10, for example, by welding. In this case, after the fixed contacts 31 are welded to the conductive terminal pins 20, it is preferable to align the height positions of the fixed contacts 31 by plastically deforming the fixed contacts 31 by pressing or the like.

[0018] The two movable contacts 32 correspond to the two fixed contacts 31, respectively. Like the fixed contacts 31, the movable contacts 32 are made of a conductive metal material, such as a clad material of a silver oxide alloy and copper or a copper alloy. The two movable contacts 32 are provided on the thermally responsive plate 35 and face the fixed contacts 31, respectively. The movable contacts 32 are formed in a shape that protrudes in a substantially hemispherical shape toward the cover plate 12 from the surface of the thermally responsive plate 35 facing the cover plate 12. The movable contacts 32 are fixed to the thermally responsive plate 35 by, for example, welding.

[0019] The support 33 is fixed to the inner surface of the housing 11 and functions to support the elastic plate 34 and the thermally responsive plate 35. The support 33 is formed, for example, by bending a rigid, long metal plate. Both longitudinal ends of the support 33 are bent so as to be parallel to the inner surface of the housing 11, and are fixed to the inner surface of the housing 11 by welding or the like. The longitudinal center of the support 33 is separated from the inner surface of the housing 11.

[0020] The elastic plate 34 has the function of elastically supporting the thermally responsive plate 35. The elastic plate 34 is made of, for example, an elastically deformable thin metal plate and is formed, for example, in a generally elliptical shape as a whole. The thermally responsive plate 35 is elastically connected to the elastic plate 34 by welding or the like directly or via another member. In this case, the elastic plate 34 is supported by the support body 33 in the form of a double-supported beam with the longitudinal center of the motor protector 2 as a fulcrum.

[0021] The thermally responsive plate 35 has the function of moving the movable contact 32 away from the fixed contact 31 when the ambient temperature inside the airtight container 10 reaches or exceeds a predetermined temperature, i.e., when its own temperature reaches or exceeds a predetermined temperature. The thermally responsive plate 35 is made, for example, from a thin, conductive bimetal or trimetal plate formed into a shallow dish shape by drawing or the like. The thermally responsive plate 35 is formed as a whole in an oval shape that is long in the longitudinal direction of the motor protector 2. The two movable contacts 32 are respectively attached by welding or the like to the surface of the thermally responsive plate 35 facing the cover plate 12 at both ends of the oval shape.

[0022] When the thermally responsive plate 35 is not operating normally, it keeps each movable contact 32 in contact with the fixed contact 31, thereby maintaining a closed state between the two fixed contacts 31. When the ambient temperature inside the airtight container 10 reaches a predetermined temperature, the thermally responsive plate 35 operates, thereby deforming each movable contact 32 in a direction away from each fixed contact 31, thereby opening the space between the fixed contacts 31.

[0023] That is, under normal conditions when the thermally responsive plate 35 is not operating, the thermally responsive plate 35 has its longitudinal ends, i.e., the two movable contacts 32, curved toward the cover plate 12, with the center of the longitudinal direction as the apex. Therefore, each fixed contact 31 is in contact with the opposing movable contact 32, and therefore the two fixed contacts 31 are electrically connected via the movable contact 32 and the thermally responsive plate 35. In other words, in this case, the two conductive terminal pins 20 are electrically connected via the fixed contacts 31, the movable contact 32, and the thermally responsive plate 35. Furthermore, the two conductive terminal pins 20 and the airtight container 10 are electrically connected via the fixed contacts 31, the movable contact 32, the thermally responsive plate 35, the elastic plate 34, and the support 33.

[0024] When the ambient temperature inside the airtight container 10 rises to a predetermined temperature at which the thermally responsive plate 35 operates, the thermally responsive plate 35 operates and deforms in a direction that reverses the curvature of the thermally responsive plate 35. This causes the movable contact 32 to be pulled away from the fixed contact 31, and the electrical connection between the two fixed contacts 31, i.e., between the two conductive terminal pins 20, and between each conductive terminal pin 20 and the airtight container 10 is cut off.

[0025] As shown in Figures 2, 4, 6, and 8, the motor protector 2 may further include a heat-generating member 40. The heat-generating member 40 is connected and fixed to the conductive terminal pins 20 outside the airtight container 10. The motor windings 91 are attached to the heat-generating member 40, for example, and electrically connected to the conductive terminal pins 20 via the heat-generating member 40. In this case, the windings 91 connected to the heat-generating member 40 do not directly contact the conductive terminal pins 20. The heat-generating member 40 is made of a different material from the conductive terminal pins 20. The heat-generating member 40 is located between the conductive terminal pins 20 and the motor windings 91 and generates heat when a current flows through it. The heat-generating member 40 is formed by bending a conductive metal plate, for example, and is attached to the conductive terminal pins 20 by welding or the like. Note that the heat-generating member 40 and the windings 91 may be connected to the heat-generating member 40 in advance, and then the lead wires may be electrically connected to the windings 91.

[0026] The heat-generating member 40 is made of a material that is conductive and has a higher electrical resistivity than any of the conductive terminal pins 20, the fixed contacts 31, the movable contacts 32, the elastic plate 34, and the thermally responsive plate 35. The material of the heat-generating member 40 may be, for example, an electrically resistant material or an electric heating material such as nickel chromium, copper nickel, copper manganese, or iron chromium. The heat-generating member 40 is formed, for example, by bending a plate of an electric heating material.

[0027] In this embodiment, the electrical resistance between the two heat-generating members 40 is set within a range of four to eight times the electrical resistance between the two conductive terminal pins 20. Therefore, when the same current flows between the two heat-generating members 40 and between the two conductive terminal pins 20, the amount of heat generated between the two heat-generating members 40 is greater than the amount of heat generated between the two conductive terminal pins 20. Note that the electrical resistance between the heat-generating members 40 includes the electrical resistance of the electrical paths between the heat-generating members 40, i.e., the conductive terminal pins 20, the fixed contacts 31, the movable contacts 32, and the thermally responsive plate 35.

[0028] Next, the holder 3 will be described. The holder 3 is used to attach the motor protector 2 to the electric compressor. The holder 3 is made of, for example, an electrically insulating resin material. As shown in FIGS. 1 to 8 , the holder 3 includes a wing portion 50 and a cover portion 60. In this embodiment, the wing portion 50 and the cover portion 60 are integrally formed. In this specification, the wing portion 50 and the cover portion 60 being integrally formed means that the wing portion 50 and the cover portion 60 are seamlessly formed by resin molding or the like without adhesive, joining, or the like.

[0029] The wing portions 50 are portions that come into contact with the motor windings when the motor protector unit 1 is attached to the motor. The wing portions 50 function to increase the contact area when attached to the motor and stabilize the posture of the holder 3. The wing portions 50 extend outward on both sides relative to the cover portion 60. For example, the wing portions 50 are formed in a flat plate shape that extends perpendicular to the longitudinal direction, i.e., the extension direction, of the conductive terminal pins 20 relative to the cover portion 60. As shown in Figures 1 to 5, the wing portions 50 are formed in a gently arc-shaped shape overall. The back surfaces of the wing portions 50 and the cover portion 60, i.e., the surfaces opposite the motor protector 2 side, are formed flat and free of protruding portions.

[0030] The cover portion 60 is provided at the center position in the longitudinal direction of the holder 3. At least a portion of the motor protector 2 is fitted into the cover portion 60, and the cover portion 60 covers a portion of the periphery of the heat-generating member 40. The cover portion 60 has, for example, a lower surface portion 61, two side surfaces 62, an upper surface portion 63, and a rear surface portion 64. The lower surface portion 61 is formed in the same plane as the wing portions 50 and constitutes the bottom surface of the cover portion 60. The two side surfaces 62 extend perpendicularly to the lower surface portion 61 at positions spaced apart from each other. The upper surface portion 63 is provided opposite the lower surface portion 61 and connects the ends of the two side surfaces 62 opposite the lower surface portion 61.

[0031] The cover 60 is configured as a rectangular ring or cylinder overall, with a bottom surface 61, two side surfaces 62, and a top surface 63, and thus the cover 60 houses the motor protector 2 inside. As shown in Figure 6 and other figures, when the motor protector 2 is housed inside the cover 60, a gap S1 exists between the bottom surface 61 and the motor protector 2, and a gap S2 exists between the side surface 62 and the motor protector 2.

[0032] 2 and other figures, the back surface portion 64 is formed in a plate shape and is connected to the bottom surface portion 61 and to portions of the two side surface portions 62 that are closer to the bottom surface portion 61. The back surface portion 64 covers the side of the airtight container 10 of the motor protector 2 housed in the cover portion 60. In this case, the motor protector 2 is fitted inside the cover portion 60 from the side opposite to the back surface portion 64, as shown in FIGS.

[0033] The back surface portion 64 not only improves the mechanical strength of the holder 3, but also functions to ensure an insulating distance between the motor and the compression mechanism when the motor protector unit 1 is attached to the motor. The motor protector unit 1 is attached to the motor 90 using a binding string 95, as shown in FIG. 14, for example. In this case, the back surface portion 64 prevents the binding string 95 from coming into contact with the motor protector 2, thereby preventing the binding string 95 from coming into contact with the high-temperature motor protector 2 and being burned off.

[0034] The holder 3 has a lower hole 611, restriction portions 621 and 641, a flow portion 631, a recessed portion 632, and an upper hole 633. As shown in Figures 4 and 9, the lower hole 611 is a hole formed through the center of the lower surface portion 61. The lower hole 611 is provided in a position facing the central portion of the apex of the housing 11 of the airtight container 10 of the motor protector 2 housed in the cover portion 60.

[0035] As shown in FIG. 9 , the restricting portion 621 is provided on the side surface 62. As shown in FIG. 11 , the restricting portion 641 is provided on the rear surface 64. Each restricting portion 621, 641 is formed by forming a portion of the side surface 62 and the rear surface 64, for example, in a stepped shape, so that it can engage with a portion of the edge of the cover plate 12. The restricting portions 621, 641 restrict movement of the motor protector 2 housed in the cover portion 60 toward the upper surface 63 by contacting the edge of the cover plate 12. In other words, the restricting portions 621, 641 have the function of defining the distance between the lower surface 61 and the motor protector 2, and the distance between the upper surface 63 and the motor protector 2.

[0036] The flow portion 631, the recessed portion 632, and the upper hole 633 are provided in the upper surface portion 63. The flow portion 631 is a hole formed through the upper surface portion 63 and has a shape and size that allows refrigerant to flow through. The recessed portion 632 is a portion formed by recessing a part of the upper surface portion 63 from the outside of the upper surface portion 63, as shown in FIGS. 1, 2, 4, and 9 to 11. The recessed portion 632 is provided at the longitudinal center position of the upper surface portion 63, i.e., a position corresponding to the vicinity of the center of the cover plate 12 of the motor protector 2. The upper hole 633 is provided inside the recessed portion 632 and penetrates the bottom of the recessed portion 632, as shown in FIGS. 1, 4, 10, and 11. That is, the upper hole 633 is formed through the upper surface portion 63.

[0037] The holder 3 also has a holding portion 65, a receiving portion 66, a guide portion 67, a protrusion 68, and an opening 69. As shown in FIG. 8 , the holding portion 65 functions to sandwich and hold the windings 91 of the motor connected to the motor protector 2. The holding portions 65 are provided on both sides of the longitudinal center of the motor protector 2. The holding portion 65 can hold, for example, one of the three windings 91 of a three-phase motor connected to the motor protector 2. In this case, the holder 3 can be arranged so that each of the three windings 91 of the three-phase motor connected to the motor protector 2 is drawn in the same direction, that is, drawn from one side, without coming into contact with the heat-generating member 40, the conductive terminal pins 20, etc.

[0038] Furthermore, the holder 3 has holding portions 65 at positions symmetrical with respect to the longitudinal center of the motor protector 2. This allows one of the three windings 91 to be pulled out in a direction different from that of the other two. Even in this case, the two windings 91 extending to both sides can be held by the holding portions 65, respectively, improving the ease of assembly to the motor.

[0039] As shown in Figures 4, 6, and 9 to 11, the receiving portion 66 is provided on the inner surface side of the lower surface portion 61. For example, the receiving portion 66 is formed in a shape with a semicircular cross section that protrudes from the lower surface portion 61 toward the upper surface portion 63. The receiving portion 66 also extends in a straight line in a direction perpendicular to the longitudinal direction of the holder 3, i.e., in the width direction of the holder 3. Two receiving portions 66 are provided on either side of the longitudinal center of the lower surface portion 61. The receiving portions 66 are intended to ensure a gap S1 between the motor protector 2 and the lower surface portion 61.

[0040] That is, when the motor protector 2 is placed inside the cover portion 60, the portion of the motor protector 2 opposite the cover plate 12 is either separated from the receiving portion 66 or in contact with the receiving portion 66. In this case, since the receiving portion 66 protrudes from the lower surface portion 61 toward the upper surface portion 63, a gap S1 is maintained between the motor protector 2 and the lower surface portion 61 even when the motor protector 2 is in contact with the receiving portion 66.

[0041] As shown in Figures 1, 4, 6, and 7, a plurality of guide portions 67 are provided on the upper surface portion 63 and protrude outward from the upper surface portion 63. As shown in Figure 14, the motor protector unit 1 is attached by tying the guide portions 67 to the coil windings 91 of the motor 90 with tying threads 95 while the motor protector 2 is fitted and held in the holder 3. The tying threads 95 are made of an electrically insulating and flexible material, such as a resin material. The holder 3 holding the motor protector 2 is attached to the windings 91 in a position within the compressor vessel 81 such that the heat-generating member 40 is exposed to the flow of refrigerant that occurs during normal operation of the compressor 80, i.e., when the compressor 80 is operating normally.

[0042] The guide portion 67 has the function of guiding the position of the binding thread 95, i.e., maintaining it in a fixed position. In other words, the binding thread 95 binding the motor protector unit 1 is prevented from shifting position by being caught in the guide portion 67. This allows the motor protector unit 1 to be securely fixed to the motor. The guide portion 67 may be, for example, a groove-shaped portion formed in the upper surface portion 63.

[0043] As shown in Figures 1, 3, 4, 5, 7, 8, and 14, one or more protrusions 68 are provided on the edge of the underside 61 and are formed in an arc-shaped shape that protrudes outward from the underside 61 and the blades 50. As shown in Figure 14, when the motor protector unit 1 is attached to the motor 90 inside the compressor container 81, the protrusions 68 contact the inner wall of the compressor container 81 before the motor protector 2 does, thereby preventing the motor protector 2 from directly contacting the compressor container 81. This prevents the motor protector 2, which is a live part, from approaching and electrically contacting the inner wall of the compressor container 81, which is a non-live part, due to vibration of the compressor 80 or a malfunction in the assembly of the motor protector unit 1.

[0044] 2 and other figures, the opening 69 is formed between the side surface portion 62 and the rear surface portion 64, closer to the lower surface portion 61. The opening 69 communicates between the inside and outside of the cover portion 60, and is configured to allow the refrigerant to flow through it.

[0045] As shown in Figure 11 and other figures, the connection structure 70 is a structure for connecting and fixing the motor protector 2 and the holder 3. In this embodiment, the connection structure 70 connects and fixes the motor protector 2 and the holder 3 in an inseparable manner. Note that in this embodiment, "connected and fixed in an inseparable manner" means that the motor protector 2 and the holder 3 cannot be separated from each other unless some structure is destroyed or removed in order to separate them. As shown in Figures 9 to 11, the connection structure 70 connects the motor protector 2 and the holder 3 with gaps S1 and S2 between them that allow a refrigerant to pass through.

[0046] In this embodiment, the connection structure 70 connects the motor protector 2 to the holder 3 with the motor protector 2 suspended from the upper surface 63 of the holder 3. In other words, the holder 3 holds the motor protector 2 with the conductive terminal pins 20 extending in the vertical direction and protruding upward.

[0047] The connection structure 70 can be configured to include a holder-side member 71 and a protector-side member 72. Both the holder-side member 71 and the protector-side member 72 are made of a metal material. As shown in Figures 5, 10, and 11, the holder-side member 71 is provided on the upper surface portion 63, and a portion of the holder-side member 71 penetrates the upper surface portion 63 and extends toward the lower surface portion 61.

[0048] The holder-side member 71 is made of metal and is formed, for example, in a T-shape as a whole, as shown in Figures 4 and 10. In this case, the holder-side member 71 has an insertion portion 711 and a locking portion 712. The insertion portion 711 is a portion of the T-shape that passes through the upper surface portion 63 and extends toward the lower surface portion 61. The locking portion 712 is a portion of the T-shape that extends perpendicular to the extension direction of the insertion portion 711.

[0049] When attaching the holder-side member 71 to the holder 3, the insertion portion 711 is inserted into the upper hole portion 633 from the outside toward the inside of the upper surface portion 63. Then, the locking portion 712 locks onto the bottom portion of the recessed portion 632, i.e., the periphery of the upper hole portion 633, and the insertion portion 711 penetrates the upper surface portion 63 and extends toward the lower surface portion 61.

[0050] The protector-side member 72 is made of metal and is formed, for example, in an L-shape. One end of the L-shape of the protector-side member 72 is welded and fixed to the cover plate 12. As shown in FIG. 11 , the other end of the L-shape of the protector-side member 72 extends perpendicularly from the cover plate 12 and is welded and fixed to the insertion portion 711 of the holder-side member 71. As a result, the holder-side member 71 and the protector-side member 72 are connected to each other, and the motor protector 2 is fixed to the holder 3 in a position suspended from the upper surface portion 63.

[0051] When fixing the motor protector 2 to the holder 3 using the connection structure 70, for example, as shown in Figures 10 and 11 , a rod-shaped jig T is passed through the lower hole 611 to push up the motor protector 2, pressing the periphery of the cover plate 12 against the restricting portions 621, 641. Then, with the periphery of the cover plate 12 pressed against the restricting portions 621, 641 by the jig T, the holder-side member 71 and the protector-side member 72 are welded and fixed together. As a result, the motor protector 2 and the holder 3 are fixed so that the holder 3 is sandwiched between the locking portion 712 of the holder-side member 71 and the cover plate 12. As a result, the motor protector 2 and the holder 3 are firmly fixed to each other with reduced rattle.

[0052] Next, the electric compressor 80 to which the motor protector unit 1 is attached and a method for attaching the motor protector unit 1 to the electric compressor 80 will be described. The motor protector 2 is connected to the neutral point of a motor 90, as shown in FIG. 7 . In this case, the power supply-side ends of the three-phase windings 91 of the motor 90 are connected to a three-phase power supply via power supply terminals 92. Looking at the neutral-side ends of each winding 91, two of the three-phase windings 91 are connected to a heat-generating member 40. The windings 91 connected to the heat-generating member 40 are electrically connected to fixed contacts 31 via conductive terminal pins 20. The remaining one of the three-phase windings 91 is fixed to a metal portion on the outside of the airtight container 10, such as the cover plate 12, by welding or the like. The winding 91 connected to the cover plate 12 is electrically connected to the movable contact 32 via the housing 11, the support 33, the elastic plate 34, and the thermally responsive plate 35. The heat generating member 40 and the winding 91 may be connected in such a manner that a lead wire is connected to the heat generating member 40 in advance, and then the lead wire and the winding 91 are electrically connected to each other.

[0053] 13 and 14 show an example in which the motor protector unit 1 having the above configuration is attached to a hermetic electric compressor 80. In the following description, the hermetic electric compressor 80 may be simply referred to as the compressor 80. The compressor 80 is a hermetic or semi-hermetic electric compressor for a refrigerant, and can be used, for example, in an air conditioner or the like to form part of a refrigeration cycle. The compressor 80 is not limited to a relatively small or medium-sized compressor with a small capacity, but may also be a large-capacity compressor.

[0054] The compressor 80 includes a compressor housing 81, a compression mechanism 82, a motor 90, and a motor protector unit 1. The compressor housing 81 is an airtight and pressure-resistant housing that constitutes the outer shell of the compressor 80. The compression mechanism 82 and the motor 90 are both provided within the compressor housing 81. That is, the compressor housing 81 houses the compression mechanism 82 and the motor 90, which includes a winding 91. The compression mechanism 82 has the function of compressing and discharging the refrigerant. The compression mechanism 82 may be, for example, not only a scroll type but also a rotary vane type.

[0055] The motor 90 has windings 91 and drives the compression mechanism 82. A suction pipe 83 and a discharge pipe 84 are airtightly connected to the compressor vessel 81. The suction pipe 83 is for guiding refrigerant from a heat exchanger (not shown) or the like to the compression mechanism 82 in the compressor vessel 81. The discharge pipe 84 is for discharging the refrigerant compressed by the compression mechanism 82 and sending it to the heat exchanger (not shown). In this specification, the term "refrigerant" also includes refrigeration oil, i.e., lubricating oil, that lubricates the compression mechanism 82.

[0056] As shown in Figure 14, the motor protector unit 1 is attached to the coil windings 91 of the motor 90 by tying them with tying threads 95. The tying threads 95 are made of an electrically insulating and flexible material such as a resin. The motor protector unit 1 is attached to the windings 91 in a position where the heat-generating member 40 is exposed to the flow of refrigerant that occurs during normal operation of the compressor 80, i.e., when the compressor 80 is operating normally, inside the compressor vessel 81.

[0057] When the compressor 80 is operating, the compressor vessel 81 is filled with gaseous refrigerant containing mist-like lubricating oil, causing a flow of refrigerant from the suction pipe 83 to the discharge pipe 84. For this reason, the motor protector unit 1 is provided, for example, in a position downstream of the compression mechanism 82 within the compressor vessel 81, i.e., for example, between the motor 90 and the discharge pipe 84. When the compressor 80 is operating, some of the refrigerant flowing from the suction pipe 83 to the discharge pipe 84 flows in and out through openings 69 on the front and back sides of the motor protector unit 1 and flows through gaps S1 and S2, thereby cooling the motor protector 2.

[0058] According to the embodiment described above, the motor protector unit 1 includes the motor protector 2, the holder 3, and the connection structure 70. The motor protector 2 has a metal airtight container 10, two conductive terminal pins 20, and an opening / closing mechanism 30. The airtight container 10 is configured to be airtight, and includes a housing 11 having an opening and an internal space, and a cover plate 12 attached to the housing 11 and covering the opening. The conductive terminal pin 20 is attached to the cover plate 12 via an electrically insulating filler 13, with one end inserted into the airtight container 10 and the other end exposed to the outside of the airtight container 10. The opening / closing mechanism 30 is provided inside the airtight container 10 and opens and closes the electrical connection between the two conductive terminal pins 20.

[0059] The holder 3 has a wing portion 50 and a cover portion 60. At least a portion of the motor protector 2 is fitted into the cover portion 60. The wing portion 50 is formed in a plate shape extending perpendicular to the longitudinal direction of the conductive terminal pin 20. The connection structure 70 connects and fixes the motor protector 2 and the holder 3 in an inseparable manner.

[0060] With this, the motor protector unit 1 is configured as a single unit with the motor protector 2 and holder 3 connected and fixed by the connection structure 70, so that the motor protector 2 and holder 3 can be prevented from separating when attaching them to the motor 90. This improves the workability when attaching the motor protector 2 to the motor 90 using the holder 3.

[0061] The motor protector unit 1 of this embodiment is disposed along the outer peripheral edge of the windings 91, with the blades 50 of the holder 3 positioned on the windings 91 side, i.e., attached so that the outer surfaces of the blades 50 are in contact with the windings 91. The motor protector unit 1 is disposed with the heat-generating member 40 facing the outer periphery of the compressor container 81. The compressor 80 is driven by an inverter-controlled power supply, and the current during locked operation is set to be equal to or smaller than the current during normal overload operation. In other words, if the compressor 80 is driven by an inverter-controlled power supply, the motor protector unit 1 described above allows the current during locked operation to be set to be equal to or smaller than the current during normal overload operation.

[0062] Here, a "phase loss" refers to a state in which one or more phases of the three-phase power supply supplied to a motor are not energized due to a broken power supply line, poor contact at the wire connections, a malfunction in the power control circuit, or a broken wire inside the motor. When starting a compressor, if the motor is energized in a phase loss state, the torque is insufficient, causing the motor rotor to lock and not rotate, resulting in a continuous flow of starting current through the motor. Because the starting current is larger than the normal operating current, if the starting current continues to flow through the motor in a phase loss state, the balance between the phases at the neutral point will be disrupted, resulting in an abnormal current flow. Generally, the starting current when attempting to start a motor from such a phase loss state is called a "phase loss lock current."

[0063] When a phase loss causes the rotor to lock, the flow of refrigerant, which contains refrigerant oil (i.e., lubricant), slows down, preventing the refrigerant from cooling the motor. If a phase loss current continues to flow through the motor while the rotor remains locked, the motor temperature will rise rapidly due to Joule heating, and in the worst case scenario, the motor may burn out. For this reason, it is important to detect the phase loss current and cut off the power supply to the motor.

[0064] However, in the case of inverter-controlled motors, due to factors such as the existence of high-voltage, high-current operating modes, the difference between the open-phase lock current and the motor's maximum rated current may be small. In this case, if the operating temperature required for the thermal plate to operate is set to match the heat generated by the open-phase lock current, the thermal plate may operate even within the rated maximum current, resulting in excessive operation. On the other hand, if the operating temperature required for the thermal plate to operate is set too high so that the thermal plate does not operate even at the rated maximum current, it takes time for the open-phase lock current to heat up the temperature inside the motor protector. As a result, when an open-phase lock occurs, the thermal plate cannot be heated to its operating temperature in a short time. It takes time for the motor protector to activate and interrupt the open-phase lock current, and during that time, the motor temperature may rise to a dangerous level.

[0065] Therefore, the connection structure 70 of the embodiment connects and fixes the motor protector 2 and the holder 3 by providing gaps S1 and S2 between the motor protector 2 and the holder 3 through which the refrigerant can pass. This prevents the motor protector 2 from over-operating within the rated maximum current or from failing to operate due to an abnormality caused by an excessive current or a lock current. That is, when the motor 90 is operating at the rated maximum current, the compressor 80 does not stop because the current is within the normal operating range, and the refrigerant in the compressor container 81 continues to flow. The refrigerant flowing in the compressor container 81 cools the motor protector 2 itself through the gaps S1 and S2. Therefore, even if the rated maximum current flows through the motor 90, the airtight container 10 is cooled by being exposed to the refrigerant flow, preventing the temperature inside the airtight container 10 from reaching the operating temperature of the thermally responsive plate 35. Therefore, in this case, the motor protector 2 does not operate, and power supply to the motor 90 continues.

[0066] On the other hand, if an abnormality such as a phase loss occurs in the motor 90 and the operation of the compression mechanism 82 stops, the flow of refrigerant in the compressor container 81 weakens or stops. The cooling of the motor protector 2 by the refrigerant also decreases, resulting in a rise in the temperature inside the airtight container 10. When the temperature inside the airtight container 10 reaches the operating temperature of the thermally responsive plate 35, the thermally responsive plate 35 operates, i.e., the motor protector 2 operates, and the power supply to the motor 90 is cut off.

[0067] As described above, with the motor protector unit 1 of this embodiment, even if the rated maximum current of the motor 90 is close to the open-phase lock current, the motor protector 2 will not operate if the motor 90 is operating within the rated maximum current. On the other hand, if the motor 90 locks and an open-phase lock current flows, the motor protector 2 can be operated in a short time. As a result, it is possible to reliably prevent excessive operation within the rated maximum current and non-operation due to an abnormality caused by an excessive current or a lock current. Furthermore, this motor protector unit 1 is particularly suitable for electric compressors driven by an inverter-controlled power supply and in which the current during lock is set to be equal to or smaller than the current during normal overload operation.

[0068] The cover portion 60 further has an upper surface portion 63 that covers the side of the motor protector 2 facing the cover plate 12, and a lower surface portion 61 that covers the side opposite the cover plate 12. The connection structure 70 has a holder-side member 71 and a protector-side member 72. The holder-side member 71 is provided on the upper surface portion 63 and extends toward the lower surface portion 61. The protector-side member 72 is provided on the cover plate 12 and extends toward the upper surface portion 63. The holder-side member 71 and the protector-side member 72 are connected to each other, and the motor protector 2 is fixed to the holder 3 in a suspended position from the upper surface portion 63. As a result, the motor protector 2 is fixed to the holder 3 in a suspended position by the connection structure 70, thereby ensuring as large gaps S1 and S2 as possible around the motor protector 2. As a result, it becomes easier to ensure the amount of refrigerant flowing around the motor protector 2, and under normal operating conditions when refrigerant is flowing, the motor protector 2 is cooled efficiently, thereby suppressing malfunction of the motor protector 2.

[0069] The holder 3 is made of resin and further has an upper hole 633 formed through the top surface 63. The holder-side member 71 is made of metal and further has an insertion portion 711 and a locking portion 712. The insertion portion 711 is a portion inserted into the upper hole 633 from the outside toward the inside of the top surface 63. The locking portion 712 extends outward in the extension direction of the insertion portion 711 and is a portion that locks onto the top surface 63. The protector-side member 72 is made of metal and is welded to the insertion portion 711. Thus, by welding the holder-side member 71 and the protector-side member 72 of the connection structure 70 together as metals, the motor protector 2 can be more reliably fixed to the holder 3.

[0070] The holder 3 further includes a lower hole 611 and restricting portions 621 and 641. The lower hole 611 is formed through the lower surface 61. The restricting portions 621 and 641 contact the motor protector 2 and restrict movement of the motor protector 2 toward the upper surface 63. By welding and fixing the holder-side member 71 and the protector-side member 72 of the connection structure 70 together while the motor protector 2 is pressed against the restricting portions 621 and 641, the motor protector 2 and the holder 3 are fixed together by sandwiching the holder 3 between the locking portion 712 of the holder-side member 71 and the cover plate 12. This reduces rattle between the motor protector 2 and the holder 3, preventing the motor protector 2 from falling off the holder 3 due to vibrations of the electric compressor 80, for example.

[0071] The above-described embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The present embodiment and its modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

Claims

1. A hermetically sealed metal container having a housing with an opening and a space inside, and a cover plate provided on the housing to cover the opening; two conductive terminal pins provided on the cover plate via a filler having electrical insulation properties, with one end inserted inside the hermetically sealed container and the other end exposed outside the hermetically sealed container; an opening / closing mechanism provided inside the hermetically sealed container to open and close the electrical connection between the two conductive terminal pins; a motor protector having the above; a covering portion into which at least a part of the motor protector is fitted; and a wing portion formed in a plate shape extending in a direction perpendicular to the longitudinal direction of the conductive terminal pins; a holder for the motor protector having the above; and a connection structure for connecting and fixing the motor protector and the holder for the motor protector; a motor protector unit comprising the above.

2. The motor protector unit according to claim 1, wherein the connection structure has a gap through which a refrigerant can pass between the motor protector and the holder for the motor protector, and connects the motor protector and the holder for the motor protector.

3. The covering portion further has an upper surface portion covering the cover plate side of the motor protector and a lower surface portion covering the side opposite to the cover plate. The connection structure has a holder side member provided on the upper surface portion and extending toward the lower surface portion side, and a protector side member provided on the cover plate and extending toward the upper surface portion side. The motor protector is fixed to the holder for the motor protector in a posture suspended from the upper surface portion with the holder side member and the protector side member connected to each other. The motor protector unit according to claim 2.

4. The holder for the motor protector is made of resin and further has an upper hole portion formed through the upper surface portion. The holder side member is made of metal and further has an insertion portion inserted into the upper hole portion from the outside to the inside of the upper surface portion, and a locking portion extending outward with respect to the extending direction of the insertion portion and locked to the upper surface portion. The protector side member is made of metal and is welded and fixed to the insertion portion. The motor protector unit according to claim 3.

5. The holder for the motor protector further includes a lower hole portion formed through the lower surface portion, and a restricting portion that contacts the motor protector and restricts movement of the motor protector toward the upper surface portion side. The motor protector unit according to claim 4.

6. An electric compressor including a motor including a compression mechanism and a winding, a compressor container that houses the compression mechanism and the motor, and the motor protector unit according to any one of claims 1 to 5, wherein the motor protector is connected to a winding on the neutral point side of the motor and is housed in the compressor container.

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