WO2020059615A1

WO2020059615A1 - Electric compressor

Info

Publication number: WO2020059615A1
Application number: PCT/JP2019/035810
Authority: WO
Inventors: 吉田　浩; 沙織栗原; 亨伊東; 将宜松田; 真之下田
Original assignee: サンデン・オートモーティブコンポーネント株式会社
Priority date: 2018-09-21
Filing date: 2019-09-12
Publication date: 2020-03-26
Also published as: JP2020045895A

Abstract

[Problem] To improve the durability of a substrate. [Solution] According to the present invention, a switching element 22 and a capacitor 23 are mounted on a substrate 21. The substrate 21 is housed in an inverter housing part 12, and an outer peripheral edge thereof is fixed by screwing at a plurality of predetermined fixation points. A cushioning material 26 is sandwiched between the substrate 21 and a bottom surface 25 of the inverter housing part 12. The cushioning material 26 is uniformly arranged in a region of the substrate 21 that is inside the fixation points.

Description

Electric compressor

The present invention relates to an electric compressor.

Patent Document 1 proposes that a power board is fixed to a plurality of fixed seats by screws in an inverter accommodating portion of an electric compressor.

JP 2009-114961 A

It is conceivable that a sheet-like cushioning material is interposed between the substrate and the housing in a portion of the substrate where the switching element is mainly provided, so as to enhance heat dissipation and vibration proofing. However, when there is a bias in the arrangement of the cushioning material, when the screws are fixed, the stress is concentrated on the fixing point on the substrate and the portion of the cushioning material, and the substrate is arranged on the substrate by causing local distortion. This can affect the durability of the device and the solder used to secure the device.
It is an object of the present invention to improve the durability of a substrate, a device disposed on the substrate, and a solder for fixing the device.

The electric compressor according to one embodiment of the present invention includes:
One board mounted with a switching element and a capacitor provided to drive and control the electric motor built in the compressor,
A housing formed integrally with the compressor, accommodating the substrate, and fixing a plurality of predetermined fixing points on an outer peripheral edge of the substrate with screws.
And a cushioning material sandwiched between the substrate and the housing, the cushioning material being uniformly arranged in a region of the substrate inside the fixed point.

According to the present invention, since the cushioning material is uniformly arranged in the region inside the fixing point on the substrate, the concentration of stress when screwing and fixing can be reduced. Therefore, local distortion can be suppressed, and the durability of the substrate, the device disposed on the substrate, and the solder for fixing the device can be improved.

It is an outline view of a compressor. It is an external view of a board | substrate. It is an arrangement view of a cushioning material. It is sectional drawing of a board | substrate. It is a figure which shows the distortion which arises in a board | substrate typically. FIG. 9 is a diagram illustrating a comparative example in which a capacitor is provided on another substrate. FIG. 3 is a diagram showing an embodiment in which a capacitor is provided on a common substrate. It is an external view of a capacitor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. In addition, the following embodiments illustrate an apparatus and a method for embodying the technical idea of the present invention, and do not limit the configuration to the following. That is, the technical idea of the present invention can be variously modified within the technical scope described in the claims.

<< One Embodiment >>
"Constitution"
FIG. 1 is an external view of the compressor.
The compressor 11 (electric compressor) is, for example, an electric scroll compressor used in a refrigerant circuit of a car air conditioner. That is, when driven by a built-in electric motor mounted on a vehicle, the refrigerant sucks, compresses, and discharges the refrigerant.
An inverter accommodating portion 12 (housing) is integrally formed on the front side in the axial direction, and is sealed by a front cover 13. A connector 14 for a low-voltage circuit and a connector 15 for a high-voltage circuit are provided on the outer wall of the inverter accommodating section 12.

FIG. 2 is an external view of the substrate.
A substrate 21 on which an inverter for driving and controlling an electric motor is formed is housed inside the inverter housing 12. The thickness of the substrate 21 is, for example, about 1.6 to 1.8 mm. The power supply is DC and the electric motor is three-phase AC. At least a plurality of switching elements 22 and a plurality of capacitors 23 are mounted on the substrate 21. The switching element 22 forms an inverter circuit that converts DC into AC, and is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The capacitor 23 forms a smoothing / filter circuit connected in parallel to the power supply line, and is, for example, an aluminum solid electrolytic capacitor.

The plane direction of the substrate 21 includes a longitudinal direction and a lateral direction. The switching elements 22 are arranged on one side in the longitudinal direction, and the switching elements 22 for three phases are arranged in the longitudinal direction in a state where the switching elements 22 are divided into two rows by the upper arm and the lower arm. The capacitor 23 is arranged on the other side in the longitudinal direction.
The substrate 21 has screw holes 24 formed at a plurality of predetermined positions on the outer peripheral edge. The board 21 is fixed to the inverter accommodating section 12 by fixing each of the holes 24 with screws.

FIG. 3 is a layout diagram of the cushioning material.
(A) in the figure is a view of the substrate 21 fixed to the bottom surface 25 of the inverter accommodating portion 12 with screws, as viewed from the side. Between the bottom surface 25 and the substrate 21, sheet-like cushioning materials 26a to 26c are sandwiched in a compressed state. Here, for the sake of simplicity, the thicknesses of the cushioning members 26a to 26c are drawn large for convenience. The cushioning members 26a to 26c are formed of a gel having high thermal conductivity. It is desirable to select a material having a different repulsion force for each of the cushioning members 26a to 26c according to the rigidity of the substrate 21 at the portion to be sandwiched. When it is not necessary to identify each of the buffer members 26a to 26c, the buffer members 26a to 26c will be simply described as the buffer members 26.

(B) in the figure shows the back surface of the substrate 21. The cushioning members 26a to 26c are evenly arranged in a region of the substrate 21 inside each of the holes 24 serving as fixed points. First, a buffer 26a is arranged on the back surface of the area where the switching element 22 is mounted. There are two buffer members 26a corresponding to the two rows of switching elements 22. Further, a cushioning material 26b is disposed on the back surface of the area where the capacitor 23 is mounted. The buffer 26c is disposed on the back surface of the region where the switching element 22 and the capacitor 23 are not mounted. Specifically, it is arranged at the center in the longitudinal direction between the region where the switching element 22 is mounted and the region where the capacitor 23 is mounted.

FIG. 4 is a sectional view of the substrate.
On the substrate 21, a power supply line pattern 27 is formed between a region where the switching element 22 is mounted and a region where the capacitor 23 is mounted. The pattern 27 is formed of a conductor such as a copper foil, and has both sides covered with an insulator or a solder resist so as not to be exposed. The pattern 27 generates heat because a large current flows when the motor is driven. The buffer material 26c is arranged in the area where the pattern 27 is formed, and also functions as a heat dissipation sheet.

《Action》
Next, main effects of the embodiment will be described.
When there is a bias in the arrangement of the cushioning material 26, stress is concentrated on the fixing point on the substrate 21 and the portion of the cushioning material 26 when screwed and fixed, and local distortion is caused to cause the substrate 21, on the substrate 21. This can affect the durability of the placed device and the solder used to secure the device.
Therefore, the cushioning material 26 is evenly arranged in a region inside the fixed point on the substrate 21. As a result, the concentration of stress can be reduced when screws are fixed. Therefore, the local distortion can be suppressed, and the durability of the substrate 21, the device disposed on the substrate 21, and the solder for fixing the device can be improved.

FIG. 5 is a diagram schematically showing a distortion generated in the substrate.
(A) in the figure shows a case where the arrangement of the cushioning material 26 is biased. If there is a bias in the arrangement of the cushioning material 26, only the portion of the substrate 21 where the cushioning material 26 is arranged swells, causing local distortion. In particular, the substrate 21 has a reduced thickness, and the surface area is increased by the integration of the switching element 22 and the capacitor 23 on one substrate 21. Therefore, the rigidity of the substrate 21 decreases, and local distortion is likely to occur.
(B) in the figure shows a case where the arrangement of the cushioning material 26 is not biased. When the cushioning members 26 are arranged evenly, local distortion is suppressed, and the deformation can be made gentle.

(4) When the compressor 11 is driven, a large current flows through the pattern 27 of the power supply line, and the substrate 21 generates heat. In order to suppress the temperature rise, a thick copper substrate has been conventionally used. For example, a thick copper six-layer substrate has an expensive pattern material and a limited number of suppliers that can produce it, resulting in an increase in cost. Therefore, the power supply line pattern 27 is thinned. In this case, heat is easily generated by reducing the cross-sectional area. However, a buffer material 26c is provided in a region where the pattern 27 is formed. Since the cushioning member 26c functions as a heat dissipation sheet, heat can be released from the bottom surface 25 of the inverter accommodating portion 12, which is a housing, and can be cooled.

Further, not only the heat generated by the pattern 27 itself but also the heat from the switching element 22 and the capacitor 23 can be absorbed and radiated. Therefore, heat generation of the entire substrate 21 can be suppressed, and durability can be improved. Further, by making the pattern 27 thinner, an increase in cost can be suppressed. In addition, since the thickness of the substrate 21 can be reduced, the versatility of the layout is improved, which leads to downsizing. The conventional thick copper substrate has a plate thickness of 3.7 mm, but the substrate 21 of the present embodiment has a plate thickness of about 1.6 to 1.8 mm. Further, since the thickness of the substrate 21 can be reduced, the thermal resistance of the thermal via in the thickness direction can be suppressed, and the heat of the mounted component can be effectively released.

Conventionally, a board on which the switching element 22 is mounted and a board on which the capacitor 23 is mounted are separated, and both are connected by a bus bar.
FIG. 6 is a diagram illustrating a comparative example in which a capacitor is provided on another substrate.
(A) in the figure is a perspective view of the inverter 31, and (b) in the figure is a side view of the inverter 31. The inverter 31 includes a substrate 32 on which a switching element is mounted, a substrate 33 on which a capacitor is mounted, and a bus bar 34. By using the bus bar 34, it is possible to prevent the capacitor from generating heat due to a large current, but this has caused an increase in cost.
In the present embodiment, the bus bar 34 can be eliminated by integrating both the switching element 22 and the capacitor 23 on one substrate 21. Thereby, an increase in cost can be suppressed and the number of parts can be reduced. Since the buffer material 26b functions as a heat dissipation sheet, heat can be released from the bottom surface 25 of the inverter accommodating portion 12 as a housing, and the capacitor 23 can be cooled.

In FIG. 6B, the current path is indicated by a thick solid line arrow. When the substrate 32 on which the switching element is mounted and the substrate 33 on which the capacitor is mounted are separated, the inductance increases due to the long current path. Therefore, it is necessary to provide the common mode coil 35 as a measure against EMC (Electro-Magnetic Compatibility).
FIG. 7 is a diagram showing an embodiment in which a capacitor is provided on a common substrate.
(A) in the figure is a perspective view of the inverter 41, and (b) in the figure is a side view of the inverter 41. In (b) of the figure, the current path is indicated by a thick solid line arrow. When both the switching element 22 and the capacitor 23 are mounted on one substrate 21, the current path is shortened and the inductance is reduced, so that the EMC performance is improved. Therefore, the common mode coil 35 can be omitted, and the number of components can be reduced.

FIG. 8 is an external view of the capacitor.
(A) in the figure shows the capacitor 36 of the comparative example. The capacitor 36 is, for example, an aluminum electrolytic capacitor and has a height of about 26 mm. When the height is L and the exciting force F is input, the moment M is represented by the following equation.
M = F × L
(B) in the figure shows the capacitor 23 of the embodiment. The capacitor 23 is, for example, an aluminum solid electrolytic capacitor and has a height of about 10.8 mm. Therefore, since the height is L / 2.4, when the exciting force F is input, the moment M is represented by the following equation.
M = F × L / 2.4

As is apparent from the above equation, when the capacitor 36 according to the comparative example is employed, a large moment M acts on the input of the exciting force F. In FIG. 6, a filter case 37 in which a capacitor 36 (not shown) is accommodated and a resin is cast is provided on the substrate 33 to take measures against vibration.
On the other hand, in the present embodiment, an aluminum solid electrolytic capacitor is used as the capacitor 23. As a result, the height is reduced to L / 2.4, and the vibration resistance against the excitation force is greatly improved. Therefore, the filter case 37 for casting resin can be omitted, and the number of parts can be reduced.

Although the above has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art.

DESCRIPTION OF SYMBOLS 11 ... Compressor, 12 ... Inverter accommodating part, 13 ... Front cover, 14 ... Connector, 15 ... Connector, 21 ... Substrate, 22 ... Switching element, 23 ... Capacitor, 24 ... Hole, 25 ... Bottom surface, 26 ... Buffer material, 26a to 26c: buffer material, 27: pattern, 31: inverter, 32: substrate, 33: substrate, 34: bus bar, 35: common mode coil, 36: capacitor, 37: filter case, 41: inverter

Claims

One board mounted with a switching element and a capacitor provided to drive and control the electric motor built in the compressor,
A casing formed integrally with the compressor, accommodating the substrate, and fixing a plurality of predetermined fixing points on an outer peripheral edge of the substrate by screwing;
An electric compressor, comprising: a cushioning member sandwiched between the substrate and the housing, the cushioning material being uniformly arranged in a region of the substrate inside the fixed point.
The buffer material is disposed in a region where the switching element is mounted and a region where the capacitor is mounted, and is also disposed in a region where the switching element and the capacitor are not mounted. The electric compressor according to claim 1.
The substrate has an area in which a power line pattern is formed between an area in which the switching element is mounted and an area in which the capacitor is mounted, and the area in which the pattern is formed also has the buffer material. The electric compressor according to claim 2, wherein
The electric compressor according to any one of claims 1 to 3, wherein the capacitor is an aluminum solid electrolytic capacitor.