WO2010118486A1

WO2010118486A1 - A housing for the control electronics of a brushless direct-current motor

Info

Publication number: WO2010118486A1
Application number: PCT/BR2010/000115
Authority: WO
Inventors: Felipe Augusto Cardoso Moraes; Lázaro Benedito DE OLIVEIRA MELO; Leandro REIS SIMÕES
Original assignee: Robert Bosch Limitada
Priority date: 2009-04-17
Filing date: 2010-04-09
Publication date: 2010-10-21
Also published as: WO2010118486A4; BRMU8900640Y1; BRMU8900640U2

Abstract

One describes a housing (11 ) for the control electronics(2) of a brushless direct current motor coupled to a fuel pump (9), the housing (11 ) containing a control integrated circuit (2) and being -sealed from the external environment, wherein the housing (11 ) is composed by a metallic basic housing (10), constituted by a metallic base (1) and a metallic cover (5), both being joined in a fluid-tight manner (7) to each other over their whole outer perimeter and by an over-molding (8), where there are electric contacts (4) for the pump and electric contacts (3) for the harness. Said housing (11) is positioned in a detachable manner outside the fuel pump (9).

Description

Title "A HOUSING FOR THE CONTROL ELECTRONICS OF A BRUSHLESS DIRECT-CURRENT MOTOR"

The present model relates to a housing for the control electronics of a brushless direct-current motor of the type usually employed for driving fuel pumps on vehicles. Description of the prior art

In direct-current (DC) motors provided with brushes, the brushes make the mechanical contact with a set of electric contacts on the rotor, called commutator, forming an electric circuit between the DC electrical source and the armature windings. During the rotation of the armature the stationary brushes come into contact with different sections of the rotating commutator. Thus, the commutator and the brushes form a set of electrical contacts, which are fired in sequence, so that electric power always flows through the armature windings that are close to the stator. The mechanical contact of the brushes with the commutator causes wear of the brushes as times - goes by, -which ultimately results -in failures and the need for maintenance.

In brushless DC motors the armature performs the function of a stator, that is, it does not move and in this form of driving the motor-pump assembly, the rotor has the function of generating the magnetic field. The commutator-brushes electric assembly is replaced in the brushless motor by an electronic controller that carries out commutation of the electric current.

Fuel pumps for vehicles employ, for the most part, brushed direct-current motors. These devices have a low purchase cost, but on the other hand, as mentioned above, they have expensive maintenance and exhibit a considerable number of failures. The automobile industry, seeking alternatives to reduce such problems, has recently opted for brushless direct- current motors for fuel pumps.

However, problems have arisen with regard to where to position the control electronics of the brushless direct-current motor.

As examples of the prior art, we can cite the following documents: US 6,042,349 and US 2005/021367 A1. In the case of US 6,042,349, Figure 1 shows the housing 22 within the motor-pump assembly. In document US 2005/021367 A1 , the electronic circuitry has been positioned within the motor in a separate housing, as can be seen from item 16 of Figure 2. This housing configuration for the electronic circuitry within the motor-pump assembly has, as a great disadvantage, the fact that it is of difficult access for the case of replacement and/or maintenance of some component of the electronic circuitry. Any service requires complete disassembly of the motor and/or the pump, it being necessary to replace the assembly as a whole. Another prior-art solution is presented in document US

2008/0053412 A1. In this document, one can see the assembly of fuel pump with the control device of the pump motor positioned in a housing at the flange of the fuel tank, as can be observed in Figure 1 , item 82. The disadvantage of positioning the housing of the electronic circuitry of the motor integrated in a fixed manner at the tank flange is that the flange has to be disassembled -completely for access to -the motor control device,- it- being necessary to replace the whole assembly instead of exchanging the components that malfunctioning or out of order, besides limiting the flexibility of the supplier of the fuel-pump assembly for a determined type of flange, which is usually specified by the vehicle assembler. In the automobile industry there is a great restriction to the space available for the flange of the fuel tank, since the latter, for the most part, is mounted under the back seat of the vehicle.

Therefore, there is the prior-art problem to be solved, namely: creating a housing for the control electronics of motors without fuel pump brushes, which will be of easy access for assembly and maintenance purposes, besides bringing about a great flexibility to the maker of the motor- pump assembly with regard to its interfaces in the vehicle, that is, the tank flange and the electric harness. Brief description of the model

The present model solves the prior-art problems mentioned before by means of a housing for the control electronics of a brushless motor for a fuel pump, which is detachable positioned outside the motor-pump assembly and mounted by engagement over it. The basic housing is made of welded two pieces of metal, within which the integrated control electronic circuit is positioned, further having glass ring seals for the electric contacts that are directed outwards of the metal base, thus being completely resistant and impermeable to the fuel ion which it is immersed. After the mounting, the basic metal housing receives, together with the electric contacts, a plastic over-molding to facilitate its mounting in a detachable manner, which takes place by engagement and/or fitting into the outer part of the motor-pump assembly. With such positioning of the housing within the tank, that is, in a detachable manner and outside of the motor-pump assembly, the flange of the fuel tank may have any shape, and so there is no need for the automobile maker altering the design thereof. In this way, one also solves the problem of easy access for mounting and/or maintenance of the electronic control circuitry, thus enabling the replacement of only faulty malfunctioning components, rather-than the whole assembly. Brief description of the drawings

The present model will now be described in greater detail with reference to an embodiment represented in the drawings. The figures show: Figure 1 - a perspective front view of the metallic base plate with the control integrated circuit;

Figure 2 - a perspective back view of the metallic base plate with the control integrated circuit;

Figure 3 - a front view of the metallic basic housing; Figure 4 - a cross-sectional view of the metallic basic housing;

Figure 5 - a front view of the housing for the electronic control circuitry;

Figure 6 - a side view of the housing for the electronic control circuitry; Figure 7 - a perspective bottom view of the housing for the electronic control circuitry; and

Figure 8 - a side view showing the housing for the control electronics mounted onto the fuel pump. Detailed description of the figures

As can be observed in figure 1 , the control electronics of the brushless electric motor of a fuel pump 9 for vehicles has a printed circuit board. This printed circuit board 2 is mounted onto a metallic base 1 , the electric contacts that are connected to the electric end receive the reference number 3, and the electric contacts that are connected to the contacts of the pump 9 receive the reference number 4.

In figure 2, one can see the metallic base 1 in a perspective back few, which shows the electric contacts 3 and 4. The latter, in turn, are sealed by class rings 6. This sealing 6 prevents the fuel present in the tank in liquid or vapor form from getting into the basic housing 10, which would damage the control electronics 2.

Figure 3 shows the metallic cover 5 positioned on the metallic base 1 , thus forming the basic housing 10. The employ of metal for this basic housing 10, as for example, stamped stainless steel for the cover 5 and mechanical construction steel with nickel or tin coating for the metallic base 1 , has the function of preventing any liquid or vapor from reaching the control integrated circuit board 2. With the liquid-tight sealing of the basic housing 10, one prevents fuel from getting into it, by virtue of the total absence of permeability of metal employed to fuel.

As is known, plastic materials have permeability to fuels (swelling), for which reason such materials are not suitable to guarantee the liquid-tightness of the basic housing 10 when mounted within the fuel tank of a vehicle.

In a cross-section shown in figure 4, one can see the metallic basic housing 10. The metallic cover 5 is joined, over its whole periphery, to the metallic base 1 by means of liquid-tight union 7, as for example, electric welding, mechanical shaping folding, etc., so as to seal completely the basic housing 10. The sealings in the form of a glass ring 6, as for example, of the Eletrovac type, as already explained, guarantee the liquid-tightness of the basic housing 10 at the outlets of the electric connections 3 and 4. Glass has been chosen for sealing also by virtue of its characteristic of total absence of permeability to the fuel.

With the basic housing 10 assembled, one -carries out the welding of the electric contacts 4 to connectors, which may be, for example, of coated FeNi. The joining of the contacts 3 to the electric harness of the fuel pump is also made at this stage, that is, prior to the over-molding with plastic material.

As can be seen in figures 5 to 7, the housing 11 is constituted by the basic housing 10, plastic over-molding 8 and the connectors of the contacts 4 and contacts 3. This over-molding 8 has, at the lower end, that is, where it is engaged and/or fitted into the pump connectors, a characteristic shape to facilitate the mounting of the connectors of the electric contacts 4, besides providing a support with greater stability for the housing 11 on the pump 9.

The over-molding 8, in turn, imparts to the- assembly -formed- by the basic housing 10 and the connectors of the contacts 4 and 3 the condition of a single component, which will account for the commutation of electric power supplied by the battery to the motor. This over-molding 8 can be made with plastic of high chemical resistance, such as polyphenylene (PPS), polyoxymethylene (POM) or polyamide (PA) plastics.

The assembly of the housing 11 , formed by the basic housing 10, connectors 4 and 3 and over-molding 8, composes, as said above, one unit, which can be easily handled, just as an electric harness, be it during the assembling or in maintenance.

Figure 5 shows a front view of the housing 11 , showing the over- molding 8 around the metallic cover 5. On the other hand, in figure 6, one can see a side view of the housing 11 , the over-molding 8 and the connectors of the contacts 4 and 3. Figure 7, in turn, shows a perspective bottom view of the housing 11 with the over-molding 8 and the connectors of the contacts 4 and 3.

The housing 11 is finally engaged and/or fitted with the pump contacts 9, as shown in figure 8. The positioning of the housing 11 in a detachable manner and outside the pump 9 enables good dissipation of the heat energy generated by the control integrated circuit 2 to the liquid of the fuel in which the housing 11 is immersed, besides providing flexibility in maintenance in the case of malfunction or non-functioning in the sense of replacement of only the faulty components, which reduces the maintenance costs.

The electromagnetic compatibility of the housing 11 , that it, limitation of electromagnetic interference, and the correct operation of various electromagnetic compounds in the same environment, is also given depending on its positioning with respect to the motor-pump assembly, its constructive design and the materials employed.

Claims

1. A housing for the control electronics of a brushless direct current motor coupled to a fuel pump (9), the housing (11) containing a control integrated circuit (2) and being sealed from the external environment , characterized in that the housing (11) is composed by a metallic basic housing (10), constituted by a metallic base (1 ) and a metallic cover (5), both being jointed in a fluid-tight manner (7) to each other over their entire outer perimeter by means of electric contacts (4) for the pump, electric contacts (3) for the electric harness and an over-molding (8), said housing (11 ) being positioned in a detachable manner outside the fuel pump (9).

2. A housing according to claims 1 , characterized in that the joining (7) between the metallic base (1 ) and the metallic cover (5) of the basic housing (10) is made by welding.

3. A housing according to claims 1 , characterized in that the joining (7) between the metallic base (1 ) and the metallic cover (5) of the

-basic housing (1.O)Js made by folding.

4. A housing according to claims 1 , characterized in that the electric contacts (3, 4) are sealed from the environment by glass rings (6).

5. A housing according to claims 1 , characterized in that the housing (11 ) is engaged and/or fitted with the contacts of the pump (9).

6. A housing according to claim 1 , characterized in that the metallic basic housing (10) is constituted by a metallic base (1) made of mechanical-construction steel, coated with nickel or tin, and a metallic cover (5) made of stamped stainless steel.

7. A housing according to claim 1 , characterized in that the electric contacts (4) are welded to coated FeNi connectors.

8. A housing according to claims 1 , characterized in that the over-molding (8) is made with plastic of high chemical resistance.

9. A housing according to claim 8, characterized in that the plastic may be polyphenylene sulfide (PPS), polyoxymethylene (POM) or polyamide (PA).