WO2010118485A1

WO2010118485A1 - A housing for the control electronics of a brushless direct-current motor

Info

Publication number: WO2010118485A1
Application number: PCT/BR2010/000114
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: BRMU8900644Y1; BRMU8900644U2; WO2010118485A4

Abstract

The present model relates to a housing (10) for the control electronics of a brushless direct-current motor, the housing (10) containing a control integrated circuit. The housing (10) is composed by a basic housing (1) for the control electronics, an over-molding (6) made of a plastic material and a male connector (4), said housing (10) being positioned in a detachable manner under the flange (11 ) of the module of the fuel pump facing the inside of the tank.

Description

"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 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 direct-current 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 direct-current 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 docu ments: 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 to the electric connector of the flange facing the inside of the tank. The basic housing may be composed of two welded pieces of metal jointed to each other in a liquid-tight manner, 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. The basic metallic housing, after assembly and welding of the electric contact to the respective connectors, receives an over-molding of plastic to bring about a mechanical unity for the assembly and to facilitate the assembly thereof in a detachable manner, which takes place by engagement and/or fitting with the connector of the flange facing the inside of the tank.

With such positioning of the housing, engaged in a detachable manner with the flange facing the inside of the tank, the flange of the fuel tank may have any shape, and there is no need to alter the design thereof on the part of the automobile maker, since the interface between the client and the flan will remain the same. 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 without the need to disassemble the whole motor-pump assembly, besides enabling the replacement of only the components that are faulty or malfunctioning, avoiding unnecessary replacements and, as a result, regenerating a lower maintenance cost. 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 basic housing;

Figure 2 - a perspective view of the metallic base of the basic housing of figure 1 ;

Figure 3 - a perspective view of the metallic cover of the basic housing of figure 1 ;

Figure 4 - a top view of the completely assembled housing;

Figure 5 - a bottom view of the housing of figure 3; Figure 6 - a side view of the housing of figure 3; Figure 7 - a front view of the housing of figure 3; Figure 8 - a perspective view of the over-molding without the basic housing of figure 3; Figure 9 - a perspective front view of the housing of figure 3, mounted under the flange of the module of the fuel pump. Detailed description of the figures

The control electronics of the brushless electric motor of a fuel pump for vehicles is provided within a basic housing shown in figure 1. This basic housing 1 may be made from a metallic base 2 and a metallic cover 3, as shown in figures 2 and 3, respectively. After the positioning of the control electronic circuitry inside it, the basic housing 1 is sealed in a liquid-tight manner, for example, by electric welding or folding by mechanical shaping and by glass rings which seal the outlet of the electric contacts. With the liquid-tight sealing of the basic housing 1 , entry of fuel into it is prevented by virtue of the total absence of permeability of the metal employed to fuel.

The employ of a metal for this basic housing 1, as for example, stamped stainless steel for the cover 3 and mechanical construction steel with nickel and tin coating for the metallic base 2, has the function of preventing any liquid or vapor from reaching the electronic circuitry board, penetrating the walls of the housing material. As it is known, plastic materials exhibit permeability to fuels (swelling), and so they are not suitable for ensuring liquid-tightness of the basic housing 1, when mounted inside the fuel tank of the vehicle. Figure 4 shows a top view of the housing 10 of the present model in its final assembled form. The housing 10 has a male connector 4, which engages with a female connector 12 at the bottom part of the flange 11 of the module of the fuel pump. After welding the electric contacts of the control circuitry positioned within the basic housing 1 with the male connector 4 and with the cables 5, one makes an over-molding 6 with a plastic material, to facilitate assembling and disassembling, and to aid in the mechanical maintenance. This plastic material may exhibit high chemical resistance, such as the plasties polyphenylene sulfide (PPS), polyoxymethylene (POM), polyamide (PA), among others.

The housing assembly 10, formed by the basic housing 1, male connector 4, cables 5 and over-molding 6, forms a unit that can be easily handled, like an electric harness, be it during assembling or during maintenance.

In figure 5, one can observe the housing 10 of the present model in a bottom view. The male connector 4, as already said, is designed for connection to the female connector 12 of the flange 1 of the module and usually has four pins. One can further see the sealing means 7 of the male connector 4. The sealing means 7 has the objective of preventing the entry of liquid or vapor coming from the tank through the interface between the male connector 4 and the female connector 12 of the flange 11 , preventing contact with the control electronics within the basic housing 1.

Figure 6 shows a side view of the housing 10 with the male connector 4, the engagement element 8 and the guide element 9. The engagement element 8 will engage/fit with a respective element at the lower part of the flange 11 , preventing disconnection between the female connector 12 and the male connector 4 due to vibration, weight force of the control- circuitry assembly itself, among others. The guide element 9 aims at facilitating this engagement/fitting.

Figure 7 shows affront view of the housing 10, where one can see the electric contacts on the male connector 4, besides the engagement element 8 and the guide element 9.

Figure 8 shows the over-molding 6 without the respective basic housing 1.

Figure 9 shows the housing 10 mounted under the flange 11 of the module of the fuel pump of a vehicle. As can be seen, the housing 10 of the control electronics of the motor is positioned under the flange 11 and engaged with the female connector 12 at the part facing the inside of the tank.

The electromagnetic compatibility of the housing 10, that is, the limitation of electromagnetic interference and the correct operation of several electromagnetic components in the same environment, is also given depending of its positioning with respect to the motor-pump assembly, its constructive design and the materials employed.

Claims

1. A housing (10) for the control electronics of a brushless direct- current motor of a fuel pump, the housing (10) containing a control integrated circuit, characterized in that the housing (10) is composed by a basic housing (1) for the control electronics, an over-molding (6) made of a plastic material and a male connector (4), said housing (10) being positioned in a detachable manner under the flange (11) of the module of the fuel pump, facing the inside of the tank.

2. A housing according to claim 1, characterized in that the metallic basic housing (1) is constituted by a metallic base (2) and a metallic cover (3), both being jointed to each other in a liquid-tight manner over their whole outer perimeter.

3. A housing according to claim 3, characterized in that the joining of the metallic base (2) and the metallic cover (3) of the basic housing is made by welding or folding.

4. A housing (10) according to claim 1 , characterized in that the over-molding (6) may be made from a plastic of high chemical resistance.

5. A housing according to claim 4, characterized in that the over- molding (6) may be made from a plastic of the type polyphenylene sulfide (PPS), polyoxymethylene (POM), polyamide (PA), among others.