Motor-driven Compressor

Abstract

A motor-driven compressor includes a motor driving circuit, which includes a capacitor electrically connected to a circuit board, and a capacitor holder, which holds the capacitor. The capacitor holder includes a side wall body, which covers a side surface of the capacitor, a first retainer, which extends from the side wall body to the circuit board and engages with a first end surface of the capacitor, and a second retainer, which extends from the side wall body in a direction away from the circuit board and holds the second end surface of the capacitor. The length of the second retainer in the extending direction of the second retainer is greater than the length of the first retainer in the extending direction of the first retainer.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a motor-driven compressor that includes a compression unit, which compresses refrigerant, an electric motor, which drives the compression unit, and a motor driving circuit, which drives the electric motor.

[0002] Japanese Laid-Open Patent Publication No. 2007-263061 describes an example of such a motor-driven compressor. The motor-driven compressor includes a motor driving circuit, which includes a planer circuit board and a plurality of electric components of various types. The electric components, which are electrically connected to the circuit board, include a switching element and a plurality of capacitors, for example. The capacitors are provided on the circuit board. Each capacitor is held by a capacitor holder.

[0003] In such a motor-driven compressor, it is desired to improve resistance of the capacitors against vibration applied via the capacitor holder so that the capacitors are restricted from escaping from the capacitor holder.

SUMMARY OF THE INVENTION

[0004] Accordingly, it is an objective of the present invention to provide a motor-driven compressor that can improve resistance of a capacitor against vibration via a capacitor holder.

[0005] To achieve the foregoing object, a motor-driven compressor including: a compression unit, an electric motor, a housing, a motor driving circuit, and a capacitor holder is provided. The compression unit is adapted to compress refrigerant. The electric motor is adapted to drive the compression unit. The housing accommodates the compression unit and the electric motor. The motor driving circuit is adapted to drive the electric motor and includes a circuit board and a capacitor that is electrically connected to the circuit board. The capacitor holder is made of a plastic and holds the capacitor. The capacitor holder includes a side wall body, and a first retainer and a second retainer. The side wall body covers the side surfaces of the capacitor. The first retainer extends from the side wall body toward the circuit board and engages with a first end surface of the capacitor to hold the capacitor. The second retainer extends from the side wall body in the direction away from the circuit board and engages with a second end surface of the capacitor to hold the capacitor. The length of the second retainer in the extending direction of the second retainer is greater than the length of the first retainer in the extending direction of the first retainer. The second retainer is elastically deformed so that the capacitor holder accommodates the capacitor.

[0006] Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

[0008] FIG. 1 is a partial cross-sectional view showing a motor-driven compressor according to one embodiment;

[0009] FIG. 2 is an exploded perspective view showing a capacitor holder, in which film capacitors are held, a coupling base, and a circuit board;

[0010] FIG. 3 is a longitudinal cross-sectional view showing the film capacitor and the capacitor holder;

[0011] FIG. 4 is a longitudinal cross-sectional view showing the state where the film capacitor is inserted into an accommodating chamber; and

[0012] FIG. 5 is a perspective view showing film capacitors and a capacitor holder in another embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Referring to FIGS. 1 to 4, one embodiment of the present invention will now be described.

[0014] As shown in FIG. 1, a motor-driven compressor 10 includes a housing H. The housing H includes a discharge housing member 11, a suction housing member 12, and a cover 13, which are made of a metal, preferably aluminum. The discharge housing member 11, the suction housing member 12, and the cover 13 are cylindrical and each include a closed end. The suction housing member 12 is coupled to the discharge housing member 11. The suction housing member 12 has a circumferential wall including a suction port (not shown) connected to an external refrigerant circuit (not shown). The discharge housing member 11 includes a discharge port 14 connected to the external refrigerant circuit. The suction housing member 12 accommodates a compression unit 15 (indicated by the broken lines in FIG. 1), which compresses refrigerant, and an electric motor 16, which drives the compression unit 15. Although not shown in the drawings, the compression unit 15 of the present embodiment includes a fixed scroll, which is fixed in the suction housing member 12, and a movable scroll, which faces the fixed scroll.

[0015] A stator 17 is fixed to the inner surface of the suction housing member 12. The stator 17 includes a stator core 17a, which is fixed to the inner surface of the suction housing member 12, and coils 17b, which are wound around teeth (not shown) of the stator core 17a. A rotatable rotation shaft 19 extends through the stator 17 in the suction housing member 12. A rotor 18 is fixed to the rotation shaft 19.

[0016] The suction housing member 12 has an end wall 12a to which the cover 13 is coupled. A planer coupling base 31 is arranged between the suction housing member 12 and the cover 13. The coupling base 31 is made of a metal, preferably aluminum. The coupling base 31 is coupled to the end wall 12a of the suction housing member 12. The coupling base 31 is thermally coupled to the suction housing member 12. The coupling base 31 serves as a coupling member, which configures a part of the housing H.

[0017] The cover 13 and the coupling base 31 define an accommodation chamber 13a in the housing H. The accommodation chamber 13a accommodates a motor driving circuit 20 that drives the electric motor 16. In the present embodiment, the compression unit 15, the electric motor 16, and the motor driving circuit 20 are arranged in this order along the axis L of the rotation shaft 19 (in the axial direction).

[0018] The electric motor 16 is supplied with power that is controlled by the motor driving circuit 20. This rotates the rotor 18 and the rotation shaft 19 at a controlled rotation speed and drives the compression unit 15. The driving of the compression unit 15 draws refrigerant from the external refrigerant circuit into the suction housing member 12 through the suction port, compresses the refrigerant in the suction housing member 12 with the compression unit 15, and discharges the compressed refrigerant to the external refrigerant circuit through the discharge port 14.

[0019] The motor driving circuit 20 includes a flat circuit board 21 and a plurality of electric components of various types, which are electrically connected to the circuit board 21. The circuit board 21 is arranged in the accommodation chamber 13a such that a mounting surface 21a of the circuit board 21 on which the electric components are arranged is perpendicular to the axis of the rotation shaft 19. The electric components include film capacitors 22, for example. The motor driving circuit 20 includes a plurality of film capacitors 22. Each film capacitor 22 includes leads 22a. The leads 22a electrically connect the film capacitor 22 to the circuit board 21.

[0020] A plastic capacitor holder 23 holds the film capacitors 22. The capacitor holder 23, which holds the film capacitors 22, is coupled to the side of the coupling base 31 that is opposite to the end wall 12a of the suction housing member 12.

[0021] A plurality of bosses 31f (only one shown in FIG. 1) projects from the surface of the coupling base 31 that is opposite to the end wall 12a of the suction housing member 12. Bolts B1 are inserted through the cover 13 and engaged with the corresponding bosses 31f to fasten the coupling base 31 to the cover 13. Accordingly, the cover 13, the coupling base 31, and the motor driving circuit 20 are combined to form a module. A bolt B2 fastens the cover 13, which is combined with the coupling base 31 and the motor driving circuit 20, to the suction housing member 12.

[0022] As shown in FIG. 2, the capacitor holder 23 includes a side wall body 23a, which covers the side surfaces of each film capacitor 22. The side wall body 23a includes hollowed polygonal shapes each configured by side walls and face the four sides of the corresponding film capacitor 22. The side wall 231a, which is positioned to face one of the four sides of each film capacitor 22, includes through-holes 23h, each of which guides a lead 22a of the corresponding film capacitor 22 to the portion of the circuit board 21 to which the lead 22a is to be coupled. The side walls 232a and 233a face each other and are integrally formed with the side wall 231a that includes the through-holes 23h. Each of the side walls 232a and 233a includes a first retaining piece 41, which serves as a first retainer, and second retaining pieces 42, which serves as a second retainer.

[0023] The first retaining pieces 41 extend from each side wall body 23a toward the circuit board 21. The first retaining pieces 41 engage with the first end surface 221 of the corresponding film capacitor 22 to hold the film capacitor 22. The second retaining pieces 42 extend from each side wall body 23a in a direction away from the circuit board 21. The second retaining pieces 42 engage with the second end surface 222 of the corresponding film capacitor 22 to hold the film capacitor 22. The length L2 of the second retaining pieces 42 in the extending direction of the second retaining pieces 42 is greater than the length L1 of the first retaining pieces 41 in the extending direction of the first retaining pieces 41. The second retaining pieces 42 can be elastically deformed.

[0024] According to the present embodiment, two first retaining pieces 41 and four second retaining pieces 42 are provided for each film capacitor 22. Specifically, each of the side walls 232a and 233a, which face each other, includes one of the first retaining pieces 41 and two of the second retaining pieces 42. Further, the first retaining piece 41 is positioned between the two second retaining pieces 42 in each of the side walls 232a and 233a. The width H1 of the first retaining pieces 41 is greater than the width H2 of the second retaining pieces 42.

[0025] As shown in FIG. 3, each first retaining piece 41 protrudes in perpendicularly from the side wall body 23a of the capacitor holder 23. Each second retaining piece 42 protrudes perpendicularly from the side wall body 23a of the capacitor holder 23. The tip end 42e of the second retaining piece 42 is shaped as a hook.

[0026] As shown in FIG. 2, the coupling base 31 includes recesses 51, which serve as engaging portions, in the surface facing the film capacitors 22. The recesses 51 are engaged with the corresponding second retaining pieces 42 and limit the amount of the elastic deformation of the second retaining pieces 42.

[0027] The operation of the present embodiment will now be described.

[0028] As shown in FIG. 4, when inserting each film capacitor 22 into the capacitor holder 23, the second retaining pieces 42 are pressed against the corresponding film capacitor 22 and elastically deformed. This facilitates the insertion of each film capacitor 22 into the capacitor holder 23.

[0029] As each film capacitor 22 is accommodated in the capacitor holder 23, the first retaining pieces 41 engage with the first end surface 221 of the corresponding film capacitor 22 to hold the film capacitor 22. Further, as the second retaining pieces 42 return to their original positions, the tip ends 42e of the second retaining pieces 42 engage with the second end surface 222 of the corresponding film capacitor 22 to hold the film capacitor 22. Thereby, each film capacitor 22 is held by the capacitor holder 23 in the state where the film capacitor 22 is held between the first retaining pieces 41 and the second retaining pieces 42. This improves the resistance of the film capacitor 22 against vibration via the capacitor holder 23. Accordingly, even if each film capacitor 22 vibrates during the running of the vehicle, the film capacitor 22 is restricted from escaping from the capacitor holder 23.

[0030] When each film capacitor 22 is inserted through the second retaining pieces 42 into the capacitor holder 23, the leads 22a are guided by the corresponding through-holes 23h to the portions of the circuit board 21 to which the leads 22a are to be connected. This facilitates the connection operation between the leads 22a and the circuit board 21.

[0031] The advantages of the present embodiment will now be described.

[0032] (1) The capacitor holder 23 includes the first retaining pieces 41 and the second retaining pieces 42. The first retaining pieces 41 extend from each side wall body 23a toward the circuit board 21. The first retaining pieces 41 engage with the first end surface 221 of the corresponding film capacitor 22 to hold the film capacitor 22. The second retaining pieces 42 extend from each side wall body 23a in a direction away from the circuit board 21. The second retaining pieces 42 engage with the second end surface 222 of the corresponding film capacitor 22 to hold the film capacitor 22. The length L2 of the second retaining pieces 42 in the extending direction of the second retaining pieces 42 is greater than the length L1 of the first retaining pieces 41 in the extending direction of the first retaining pieces 41.

[0033] The second retaining pieces 42 are elastically deformed so that the corresponding film capacitor 22 is accommodated in the capacitor holder 23. This facilitates the insertion of the film capacitors 22 into the capacitor holder 23 when inserting the film capacitors 22 into the capacitor holder 23 since the second retaining pieces 42 are pressed and elastically deformed by the corresponding film capacitor 22.

[0034] As each film capacitor 22 is accommodated in the capacitor holder 23, the first retaining pieces 41 engage with the first end surface 221 of the corresponding film capacitor 22 to hold the film capacitor 22. Further, as the second retaining pieces 42 return to their original positions, the second retaining pieces 42 engage with the second end surface 222 of the corresponding film capacitor 22 to hold the film capacitor 22. Accordingly, each film capacitor 22 is held by the capacitor holder 23 in the state where the film capacitor 22 is held between the first retaining pieces 41 and the second retaining pieces 42. This improves the resistance of the film capacitor 22 against vibration via the capacitor holder 23.

[0035] (2) A plurality of the second retaining pieces 42 are provided on each film capacitor 22. Each first retaining piece 41 is located between adjacent two of the second retaining pieces 42 in each of the side walls 232a and 233a. The width H1 of the first retaining pieces 41 is greater than the width H2 of the second retaining pieces 42. According to this, since a plurality of the second retaining pieces is provided on each film capacitor 22, the holding force for holding the film capacitor 22 is improved in comparison to the case where only a single second retaining piece 42 is provided on each film capacitor 22.

[0036] Further, the length L1 of the first retaining pieces 41 in the extending direction of the first retaining pieces 41 is less than the length L2 of the second retaining pieces 42 in the extending direction of the second retaining pieces 42, and the width H1 of the first retaining pieces 41 is greater than the width H2 of the second retaining pieces 42. Accordingly, the first retaining pieces 41 are less easily elastically deformed than the second retaining pieces 42. Thus, when the film capacitors 22 are inserted through the second retaining pieces 42 into the capacitor holder 23, the first retaining pieces 41 are less easily elastically deformed. Therefore, each film capacitor 22 is restricted from being pushed to the first retaining pieces 41. This allows the first end surface 221 of the film capacitor 22 to be reliably engaged with the first retaining pieces 41.

[0037] (3) Each side wall body 23a of the capacitor holder 23 includes the through-holes 23h, which guide the leads 22a to the portions of the circuit board 21 to which the leads 22a are to be connected. According to this, when inserting the film capacitors 22 through the second retaining pieces 42 into the capacitor holder 23, the through-holes 23h guide the leads 22a to the portions of the circuit board 21 to which the leads 22a are to be connected. This facilitates the connection operation between the leads 22a and the circuit board 21.

[0038] (4) The through-holes 23h are formed in the side wall 231a of the capacitor holder 23 positioned to face one of the four sides of each film capacitor 22. The side walls 232a and 233a face each other and are integrally formed with the side wall 231a including the through-holes 23h. Each of the side walls 232a and 233a includes the first retaining piece 41 and the second retaining pieces 42. According to this, the through-holes 23h are formed in a side wall different from those of which the first retaining pieces 41 and the second retaining pieces 42 are provided. This facilitates the insertion of the film capacitors 22 into the capacitor holder 23 in comparison to the case where the through-holes 23h, and the first retaining pieces 41 and the second retaining pieces 42 are formed in a single side wall. Since the single first retaining piece 41 and the two second retaining pieces 42 are provided on the side walls 232a and 233a that face each other, the holding force for holding the corresponding film capacitor 22 is further improved.

[0039] (5) The recesses 51 are engaged with the corresponding second retaining pieces 42, and limit the amount of the elastic deformation of the second retaining pieces 42. According to this, the amount of the elastic deformation of the second retaining pieces 42 is limited by the recesses 51 so that the holding force of the capacitor holder 23 for holding the film capacitors 22 is further improved.

[0040] (6) Since the second retaining pieces 42 are elastically deformed, the second retaining pieces 42 include the rigidity less than that of the first retaining pieces 41. Therefore, the holding force of the second retaining pieces 42 for holding the film capacitors 22 is less than the holding force of the first retaining pieces 41 for holding the film capacitors 22. Accordingly, in the present embodiment, the four second retaining pieces 42 are provided for each film capacitor 22. This increases the number of the portions in the second end surface 222 of the film capacitor 22 by which the film capacitor 22 is held. Accordingly, the holding force for holding the film capacitor 22 is ensured.

[0041] The above described embodiment may be modified as follows.

[0042] As shown in FIG. 5, two first retaining pieces 41 may be provided on each of the side walls 232a and 233a, which face each other. The number of the first retaining pieces 41 and the second retaining pieces 42 is not limited.

[0043] In the embodiment, it is not necessary to provide the first retaining pieces 41 and the second retaining pieces 42 on each of the side walls 232a and 233a, which face each other. For example, the first retaining pieces 41 and the second retaining pieces 42 may be formed on the side wall 231a, which includes the through-holes 23h. For example, the first retaining pieces 41 or the second retaining pieces 42 may be formed on the side wall 231a, which includes the through-holes 23h.

[0044] In the embodiment, for example, the coupling base 31 may include protrusions such that the protrusions engage with the second retaining pieces 42 to limit the amount of the elastic deformation of the second retaining pieces 42. In this case, the protrusions serve as engaging portions.

[0045] In the embodiment, the width H1 of the first retaining pieces 41 may be the same as the width H2 of the second retaining pieces 42. The width H1 of the first retaining pieces 41 may be less than the width H2 of the second retaining pieces 42.

[0046] In the embodiment, the coupling base 31 may be omitted. Further, the capacitor holder 23 may be coupled to the end wall 12a of the suction housing member 12. In this case, the end wall 12a of the suction housing member 12 serves as a coupling member to which the capacitor holder 23 is coupled. The recesses 51 may be formed in the surface of the end wall 12a facing the capacitor holder 23.

[0047] In the embodiment, the number of the film capacitor 22 is not particularly limited. That is, the number may be appropriately changed.

[0048] In the embodiment, the capacitors may include an electrolytic capacitor, for example.

[0049] In the embodiment, the motor driving circuit 20 may be located radially outward of the rotation shaft 19, for example.

[0050] In the embodiment, the compression unit 15 may be of a piston type or a vane type, for example.

[0051] In the embodiment, the motor-driven compressor 10 may be used for any air conditioning device other than that installed in a vehicle.

[0052] Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.

Claims

1. A motor-driven compressor, comprising: a compression unit adapted to compress refrigerant; an electric motor adapted to drive the compression unit; a housing that accommodates the compression unit and the electric motor; a motor driving circuit that is adapted to drive the electric motor and includes a circuit board and a capacitor that is electrically connected to the circuit board; and a capacitor holder that is made of a plastic and holds the capacitor, wherein the capacitor holder includes a side wall body, which covers a side surface of the capacitor, a first retainer, which extends from the side wall body toward the circuit board and engages with a first end surface of the capacitor to hold the capacitor, and a second retainer, which extends from the side wall body in a direction away from the circuit board and engages with a second end surface of the capacitor to hold the capacitor, wherein a length of the second retainer in an extending direction of the second retainer is greater than a length of the first retainer in an extending direction of the first retainer, and the second retainer is elastically deformed so that the capacitor holder accommodates the capacitor.

2. The motor-driven compressor according to claim 1, wherein the second retainer is one of a plurality of second retainer provided for the capacitor, the first retainer is provided such that the first retainer is located between an adjacent pair of the second retainers, and a width of the first retainer is greater than a width of each of the second retainer.

3. The motor-driven compressor according to claim 1, wherein the capacitor includes a lead, which protrudes from the capacitor, wherein the capacitor is electrically connected through the lead to the circuit board, and the side wall body includes a through-hole, which guides the lead to a portion of the circuit board to which the lead is to be connected.

4. The motor-driven compressor according to claim 3, wherein the capacitor has a substantially cuboid shape, the side wall body has a hollowed polygonal shape configured by a plurality of side walls, which surround four sides of the capacitor, the through-hole is formed in one of the side walls that is positioned to face one of the four sides of the capacitor, and the first retainer and the second retainer are provided in each of two of the side walls that face each other, wherein the two side walls that face each other are formed to be continuous with the side wall in which the through-hole is formed.

5. The motor-driven compressor according to claim 1, further comprising a coupling member, which configures a part of the housing, wherein the capacitor holder is coupled to the coupling member, and the coupling member includes an engaging portion, which engages with the second retainer to limit an amount of elastic deformation of the second retainer.

6. The motor-driven compressor according to claim 5, wherein the engaging portion includes a recess.

7. The motor-driven compressor according to claim 1, wherein the capacitor is a film capacitor.

8. The motor-driven compressor according to claim 1, further comprising a rotation shaft that is accommodated in the housing and rotated integrally with a rotor of the electric motor, wherein the compression unit, the electric motor, and the motor driving circuit are arranged in this order along an axis of the rotation shaft.

9. The motor-driven compressor according to claim 1, wherein the motor-driven compressor is mounted on a vehicle.