Patent Application
20100143165
The present invention relates to an electric compressor with an integral inverter, incorporated in a compressor with a motor drive circuit that includes the inverter, and specifically relates to an electric compressor with an integral inverter in which it is easy to perform charging or coating of resin in order to insulate and protect the motor drive circuit, and of which the weight and cost can be reduced by reducing the amount of the resin for charging or coating as far as possible.
In a known structure of an electric compressor incorporated with a motor drive circuit including an inverter, etc., a motor drive circuit is coated by a resin mold material for insulation so as to be buried in the resin mold material. (e.g. patent document 1)
Further, in another known structure, a power semiconductor module located between a lid and a compressor housing (at the low pressure side in the housing) is coated and buried by pouring a insulating synthetic resin which has been heated to be fluidized. (e.g. patent document 2)
Patent document 1: JP-2002-70743
Patent document 2: JP-4-80554
However, in the above-described conventional structure, it is difficult to perform work easily because the resin material for insulation has to be properly charged into a comparatively small space where the motor drive circuit has been installed and properly coat the motor drive circuit, and scrupulous attention and mastery of skills are necessary in order not to damage a motor drive circuit at the time of the coating and charging of the resin.
In addition, because it is a structure where the motor drive circuit is substantially buried, the amount of the resin for charging or coating increases, so that it becomes difficult to reduce the cost and weight as a whole electric compressor. And especially for an electric compressor used in an air conditioning system for vehicles, etc., it is required to reduce the weight and cost as far as possible.
According to such problems and needs in conventional electric compressors, an object of the present invention is to provide an electric compressor with an integral inverter incorporated with a motor, in which the structure of the resin coated section in the motor drive circuit is simple, easy to coat, cost-cut and lightweight with the reduced resin amount.
To achieve the above-described object, an electric compressor with an integral inverter according to the present invention is a compressor which is incorporated with a motor and provided in a compressor housing with a motor drive circuit that includes the inverter, characterized in that at least some of electric parts including the motor drive circuit are coated at an assembly-completed state with a resin material at a predetermined thickness.
In other words, although the motor drive circuit is substantially buried in the resin material in the above-described conventional structure, a site which needs to be coated is coated with the resin material at the predetermined thickness (namely, much more thinly than the buried form) in the present invention. Because the site which needs to be coated is only coated with the resin material at a small thickness at a predetermined assembly-completed state, there is no fear of damaging or burdening the electric parts including the motor drive circuit, in structure or weight, so that a desirable coat is completed simply by coating to make the work extremely easy. Further, because the coating can be performed at a small thickness, the amount of resin usage can be little and reduction in weight and cost as the whole compressor becomes possible at the same time.
In the electric compressor with an integral inverter according to the present invention, specifically in a case that refrigerant as a fluid is compressed, it is preferred that at least some of electric parts including the motor drive circuit are provided in the compressor housing so as to enable heat exchange with the refrigerant which is sucked as a fluid to be compressed. In other words, it is preferred that the motor drive circuit is provided in or near a compressor housing positioned at the suction path of the refrigerant, where heat exchange to a side of the sucked refrigerant can be performed. Employing such a structure, the inverter liable to become overheated can be properly cooled automatically, can maintain the designated performance of the motor drive circuit and can simplify the structure because a cooling means is not required to be provided separately.
Further, it is preferred that at least some of electric parts including the motor drive circuit are coated by pouring a liquid resin material, employing a casting method. Here, “casting method” means a series of processes, from a process pouring a predetermined amount of the liquid resin material into a target site to a process draining properly a surplus of the poured liquid resin material. Coating work can be much more simplified because coating of the liquid resin material can be performed extremely easily by employing a casting method. In addition, because the surplus resin material is drained any of the resin usage is not wasted. Further, the other coating method such as so-called dip coating, etc. can be also employed as a coating method of the liquid resin material.
Further, it is also preferred that at least some of electric parts including the motor drive circuit are coated under a residual heat condition after heating. Because in such a case, a film thickness can be controlled responding to the residual heat, this technique can be adopted when a relatively thick thin film is required.
A thermosetting resin, such as urethane or epoxy based resin is preferably used as a resin material for coating. The thermosetting resin can maintain the heat resistance against the heat generated at the inverter, etc. and maintain even the durability, after hardening properly.
Further, the thickness in coating is preferably 0.2 mm or more. The reason is that the coating of the present invention is intended to get a proper thickness that is required for the insulation or protection, etc., unlike the spraying coat for a corrosion prevention, etc. (In such a case an extremely thin film is generally formed.) Though the upper thickness is not limited, it is preferable that the thickness is set less than about 2 mm because too large thickness may cause the same problem as conventional buried forms.
As described above, the coating is performed at an predetermined assembly-completed state in the electric compressor with an integral inverter according to the present invention. Specifically, It is preferred that the electric parts including the motor drive circuit are mounted in the compressor and that coating is performed after a lid member protecting the electric parts has been attached to the compressor housing. Because it is the coating in a state protected by the lid member, the fear that a damage may be caused by the coating is further completely removed. Additionally, because use of the lid member can make it possible to pour and drain the liquid resin material more exactly into a predetermined site, the coating by casting method, etc. can be much more simplified.
The electric compressor with an integral inverter according to the present invention is specifically suitable for a compressor used in an air conditioning system for vehicles which strongly requires the reduction in cost and weight as a whole compressor.
In the electric compressor with an integral inverter according to the present invention, because the motor drive circuit is coated at the assembly-completed state with the resin material at the predetermined thickness, the resin coating can be performed more simply and easily, and the whole compressor can be reduced in cost and weight by the less amount of the resin usage.
Hereinafter, desirable embodiments of the present invention will be explained referring to figures.
Motor drive circuit 21 for motor 7 is provided in compressor housing 12 (front housing), and specifically, motor drive circuit 21 is provided at the exterior side of partition wall 22 which is formed in compressor housing 12 separating from the side of the refrigerant suction path. Motor drive circuit 21 supplies electric power to motor 7 via lead wire 24, and via seal terminal 23 (output terminal of motor drive circuit 21) attached by penetrating through partition wall 22, and the side of refrigerant suction path and the side of a section placing motor drive circuit 21 are sealed at a section placing seal terminal 23. By providing motor drive circuit 21 at an exterior side of partition wall 22, at least some of electric parts including motor drive circuit 21 can exchange heat through partition wall 22 with suction refrigerant, so as to be cooled by suction refrigerant.
Motor drive circuit 21 includes IPM 25 (Intelligent Power Module) which can perform an inverter function and control circuit 26, and electric parts such as capacitor 27, etc. are provided with it separately or integrally. Motor drive circuit 21 is connected to an external power supply (not shown) through connector 28 as an input terminal. The opening side toward the outside of compressor housing 12 where electric parts including motor drive circuit 21 are mounted is covered in a state sealed with lid member 29, and these electric parts are protected by lid member 29.
Coating (so-called chocolate coating in a thin film) of electric parts such as motor drive circuit 21 and capacitor 27, etc. is performed at an assembly-completed state with a thermosetting resin such as urethane or epoxy at a predetermined thickness (for example, 0.2 mm or more thickness). Such a coating can be performed by pouring via a resin inlet (arbitrarily formed on lid member 29, preferably as it can be closed after used) the liquid resin material into housing 12 where electric parts are mounted, and spreading it. After the pouring in, the surplus resin can be drained from an outlet (arbitrarily formed on lid member 29, preferably as it can be closed after used), and the inlet and outlet may be sealed after the completion of the coating. As shown in the Fig., resin 31 is poured and surplus resin 32 is drained. Further, for a coating method, the coating thickness can be appropriately controlled under a residual heat condition caused by preheating electric parts, etc as described above.
Thus, by coating of motor drive circuit 21, etc. at an assembly-completed state with the resin material at a predetermined thickness, the resin coating can be made simple and easy in comparison with the conventional charging of resin to bury electric parts. In addition, because a thin film coating is enough to be performed, the resin usage amount can be greatly reduced and therefore, the weight and cost of the whole compressor can be reduced.
Especially in the above-described embodiment, a desirable coating can be completed simply by pouring the resin inside and draining the surplus resin, in a condition that lid member 29 is mounted, and the resin coating can be much more simplified.
The coating structure according to the present invention can be applied to a general compressor with an integral inverter, and is specifically suitable to a compressor used in an air conditioning system for vehicles which strongly requires lightweight and cost reduction as a whole compressor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-042159 | Feb 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/052340 | 2/13/2008 | WO | 00 | 2/2/2010 |
