GB2362267A

GB2362267A - A sealed casing for a regulator circuit in a motor vehicle

Info

Publication number: GB2362267A
Application number: GB0106639A
Authority: GB
Inventors: Kamal Mourad; Virgilio Crestani
Original assignee: BTM SRL
Current assignee: BTM SRL
Priority date: 2000-03-21
Filing date: 2001-03-16
Publication date: 2001-11-14
Anticipated expiration: 2021-03-16
Also published as: IT1319984B1; GB0106639D0; FR2806854A1; ES2181583B1; ITTO20000265A0; GB2362267B; DE10113559A1; ES2181583A1; ITTO20000265A1

Abstract

The regulator casing comprises at least one circuit board from which a plurality of insulated electrical wires (3, 3'; 4, 4') extend,<BR> ```a dish-shaped metal container (10) in which the circuit board is fitted and which has at least one slot or opening (21) through which the electrical wires can extend, and a seat adjacent the slot or opening (21),<BR> ```a grommet (25) of electrically insulating material, through which the wires extend and which can be fitted in the seat in the container (10), the grommet (25) having an internal duct which, after the grommet has been positioned in the seat, permits the injection of a setting sealant material for sealing the spaces between the wires (3, 3', 4, 4') and the grommet (25) in a leaktight manner, and<BR> ```a cover (40) fined on the container (10) over the circuit board. The spaces between the cover (40), the container (10), and the grommet (25) are sealed in a leaktight manner by means of a setting sealant. The circuit board is an electronic speed regulator for an electric motor, particularly for a fan associated with a car radiator.

Description

2362267 Speed Regulator for an Electric Motor The present invention

relates to an electronic speed regulator for an electric motor, particularly for a fan associated with a heat exchanger such as a radiator of the liquid cooling system of a motor vehicle's internal combustion engine.

There are known electronic speed regulators which comprise a substantially dish-shaped metal container in which at least one circuit board carrying components actually constituting the electronic regulation circuit is mounted. In order to protect the circuit, a setting synthetic resin is cast in the container and covers the circuit board.

This known solution has various disadvantages.

In the first place, the use of a resin casting for protecting the circuit leads to an increase in the weight of the device as a whole.

This solution is also quite expensive since it involves the use of special resins having predetermined dielectric and heat-resistance characteristics.

The object of the present invention is therefore to enable an electronic regulator to be produced more easily and inexpensively by avoiding the use of a resin casting and the corresponding increase in the weight of the device.

Claims

This and other objects are achieved, according to the invention, by the

device defined in Claim 1 and by the method according to Claim 7.

Further characteristics and advantages of the invention will become clear from the following detailed description, given purely by way of nonlimiting example with reference to the appended drawings, in which:
2 Figure I is a perspective view of a first electronic speed regulator according to the invention for use with a direct-current electric motor of the type with brushes, Figure 2 is a partially-exploded, perspective view of the regulator of Figure 1, Figure
3 is a front view, taken on the arrow III of Figure 2, of a portion of a grommet included in the regulator according to Figures I and 2, Figure
4 is a plan view taken on the arrow IV of Figure 3, Figure
5 is a view sectioned on the line V-V of Figure 4, Figure 6 is a plan view from below, taken on the arrow VI of Figure 3, Figure 7 is a plan view from above of another portion of a grommet included in the regulator according to Figures I and 2, taken on the arrow VII of Figure 2, Figure 8 is a view sectioned on the line VIII-VIII of Figure 7, Figure 9 is a view sectioned on the line IX-IX of Figure 7, Figure 10 is a plan view from below, taken on the arrow X of Figure 9, Figure I I is an exploded, perspective view of a variant of the regulator according to the invention for use in association with a brushless electric motor, Figure 12 is a perspective view of a further variant of the electronic speed regulator according to the invention, Figure 13 is a partially-exploded, perspective view of the regulator of Figure 12, 3 Figure 14 is a side view showing a grommet device included in the regulator of Figures 12 and 13, on an enlarged scale, Figure 15 is an axial section through the grommet device of Figure 14, and Figure 16 is a section taken on the line XVI-XVI of Figure 15.

In Figures 1 and 2, an electronic speed regulator according to the invention, for a direct-current electric motor of the type with brushes, is generally indicated 1.

As can be seen in Figure 2, the regulator 1 comprises, basically, a circuit board 2 carrying the components of the electronic regulation circuit. Two insulated electrical wires 3 and 3' for conducting a supply current and a plurality of insulated wires 4 and 4' for carrying signals extend from the board 2.

In known manner, the circuit board 2 may comprise electronic power switches 5 such as, for example, MOSFET transistors provided with their own heat sinks.

In the embodiment shown by way of example, the circuit board 2 is actually formed in two separate portions 6 and 7 interconnected by a plurality of conductor bridges 8 and 9.

The regulator 1 also comprises a substantially dish-shaped container 10, made of a metal, for example, aluminium.

In the embodiment shown by way of example in Figures 1 and 2, the container 10 has the shape of an annular dish and, to enable it to be fixed to a support structure, has a plurality of radially outwardlyprojecting appendages 11.

A seat 12 is defined inside the tubular central portion of the container 10 for housing a bush 13 (Figure 1) having the function of a rotation support for an end of the shaft of the electric motor (not shown), with which the regulator is to be associated.

As can be seen in Figure 2, two pins 14 extend from the base of the container 10 and act as locators for the correct positioning of the circuit board 2. The pins 14 are intended to be engaged in corresponding holes 15 in the circuit board 2. The circuit board 2 also has a pair of holes 16 for the insertion of fixing screws (not shown), to be screwed into threaded holes in two projections 17 which protrude from the base of the container 10 (Figure 2).

In the base of the container 10 there is also an element 18 for the fixing of a shaped metal member 19, resilient appendages of which are intended to establish contact with the heat sinks of the MOSFET transistors 5 to ensure a good transfer of heat from these transistors to the container 10.

The side wall of the metal container 10 has a plurality of ventilation holes or windows 20 adjacent its mouth.

A slot, indicated 21, is also formed in the side wall of the container 10. Inside the container 10, adjacent the slot 21, there is a substantially prismatic seat 22 (Figure 2). A projection 23 with a threaded hole 24 extends from the base of this seat. A lower grommet or block element, generally indicated 25 in Figures I and 2, is fitted in the seat 22. The grommet element 25 can best be seen in Figures 3 to 6 to which particular reference will now be made.

The grommet element 25 is advantageously made of a moulded plastics material. In the embodiment shown, it has, in its upper portion, two substantially parallel main channels 26 and 27 having semicircular crosssections for housing the supply wires 3 and 3', respectively.

Two adjacent parallel grooves 28 formed in the base portion of the channel 26 define recesses for housing the signal wires 4 which extend from the circuit board 2. Similarly, a longitudinal groove 29 for housing the signal wire 4' is formed in the base portion of the main channel 27.

A through-hole 30 formed in the body of the grommet element 25 (Figures 4 to 6) opens at its lower end into a cavity 31 (Figures 5 and 6) which can house the projection 23 that extends into the seat 22 of the metal container 10 (Figure 2).

As can be seen in particular in Figures 4 to 6, two ducts 32 and 33 formed in the body of the grommet element 25 extend from its upper face, where they open into the channels 26 and 27, respectively, to its lower face. On its periphery, the body of the grommet element 25 also has a plurality of channels which define a plurality of spaces relative to the inner surface of the seat 22 in the metal container 10. In particular, the grommet element 25 has channels, indicated 34, on its front and rear faces (Figures 3 and 6). On the other two side walls, the grommet element has channels indicated 35 and 36, and channels or recesses, indicated 37 and 38 are formed on its base (Figure 6).

With ftirther reference to Figures 1 and 2, the regulator illustrated therein also comprises a cover 40 of electrically insulating material, for example, moulded plastics material. In the embodiment shown in Figures 1 and 2, the cover 40 has an annular shape substantially corresponding to the annular shape of the metal container 10. It thus has a central opening 41 (Figure 2) which is disposed around the central tubular portion 12 of the metal container 10 when the cover is in the fitted condition.

Two holes 42 (only one of which is visible in Figure 2) are also formed in the cover 40 for the insertion of fixing screws which extend through the holes 16 in the circuit board 2 and are screwed into the threaded holes in the projections 17 in the metal container 10.

The cover 40 also has two slots 49 (Figure 2) through which electrical connection terminals 43 in the form of flat pins fixed to the circuit board 2 (Figures 1 and 2) extend.

In the embodiment shown by way of example in Figures 1 and 2, an upper grommet or block element, generally indicated 45, formed integrally in a portion of the periphery of the insulating cover 40, cooperates with the lower grommet element 25 already described.
6 The upper grommet element 45 can best be seen in Figures 7 to 10 to which reference will now be made.

This grommet element has a front wall 46 (Figures 2, 7 and 8) for engaging in the slot 21 in the metal container 10 (Figure 2), above the front face of the lower grommet element 25. The front wall 46 of the grommet element 45 is connected to a body 47 in the lower portion of which there are two parallel channels 48, 49 having substantially semicircular cross-sections complementary with those of the channels 26 and 27 of the lower grommet element 25. A through-hole 50 substantially perpendicular to the axes of the channels is formed in the central portion of the body 47, between the channels 48 and 49. When the cover 40 is fitted on the container 10, the hole 50 in the upper grommet element 45 is aligned with the hole 30 in the lower grommet element 25 and with the threaded hole 24 in the appendage 23 which extends into the seat 22 in the metal container 10. All of the elements just mentioned can thus be clamped together by means of a single fixing screw (not shown).

With further reference now to Figures 7 to 10, two ducts 5 1 and 52 formed in the body 47 of the upper grommet element 45 (see in particular Figures 7 and 10) intersect the channels 48 and 49 perpendicularly. Moreover, as in the lower grommet element 25, peripheral recesses or channels such as those indicated 53 and 54 in Figures 7, 9 and 10 are also formed in the body 47 of the upper grommet element 45.

The electronic speed regulator described up to now is produced substantially in the following manner.

First of all, the lower grommet element 25 is fitted in the metal container 10 in which the support bush 13 has previously been mounted, in particular, the lower grommet element 25 is positioned in the seat 22.

The pre-assembled circuit board 2 is then positioned in the container 10, care being taken to place its wires 3, 3' and 4, 4' in the corresponding channels 26-29 of the lower grommet element 25. The circuit board 2 is fixed to the metal container 10 by means of screws.
7 The cover 40 is then placed in the container 10, over the circuit board 2, so that the upper grommet element 45 is coupled with the lower grommet element 25. During the positioning, the terminals 43 of the circuit board 2 are arranged projecting above the cover 40 through its slots 49. The cover is fixed to the container 10 by means of screws which extend through the holes 42 in the cover and through the holes 16 in the circuit board 2 and are screwed into the holes in the projections 17 in the container 10.

Upon completion of the above-mentioned steps, the regulator is sealed in a leaktight manner.

This sealing step provides for the injection of a setting sealant material into the minuscule spaces defined between the cover 40 and the metal container 10 as well as between the grommet elements 25 and 45, the slot 21, and the seat 22 in the metal container 10. The spaces between the terminals 43 and the corresponding slots in the cover 40 are also sealed by the injection of setting sealant. The sealing step also involves the injection of the sealant, by means of suitable thin needles, into the grommet or block as a whole, formed by the upper grommet element 45 and the lower grommet element 25. This injection of sealant takes place after the insertion of the injection needle through the openings 51 and 52 (Figures 7 and 10) and then into the ducts 32 and 3 3 (Figures 4 and 5) so that the sealant is also injected into the spaces defined between the lateral surface and the lower face of the grommet element 25 and the seat 22 in the metal body 10. The sealant is injected in a manner such that it also completely fills the ducts 32, 33 and 51, 52 which communicate with the seats or channels in which the wires 3, 3' and 4, 4' extend so that the spaces defined between these wires and the grommet elements are also sealed in a leaktight manner.

The above-mentioned sealing steps may be performed manually or automatically by means of a machine provided for the purpose.
8. An electronic speed regulator substantially as herein described with reference to and as illustrated in the accompanying drawings.

8 Upon completion of the sealing, the region between the cover 40, the metal container 10, and the grommet or block 25, 45 is effectively isolated from the outside environment, although it has not been filled with a resin casting as in regulators according to the prior art.

Figure I I shows a variant of the regulator according to the invention for use in association with a brushless electric motor. This variant differs from that described above substantially in a different composition of the regulation circuit, and in that the circuit board no longer has terminals (such as the terminals 43 of Figure 2) for connection to a brush-holder. Moreover, the cover 40 is preferably made of metal so that it can be used as a heat sink and the upper grommet element 45 is separate from the cover. Otherwise, from the point of view of its structure, assembly and sealing, the embodiment shown in Figure I I corresponds substantially to that described above.

Figure 12 and the following figures show a variant of the device according to the invention.

Whereas in the embodiments of the previous drawings, the electronic speed regulator is to be connected directly to the associated electric motor, with or without brushes, the embodiment which will be described with reference to Figure 12 and the following figures is for mounting in a location separate from that of the motor with which it is associated.

In Figures 12 and the following figures, parts and elements similar to those already described above have again been attributed the same reference numerals.

In the embodiment of these drawings, the electronic speed regulator I comprises a metal container 10 in the form of a substantially parallelepipedal dish in which a circuit board 2 carrying the components of the actual regulation circuit is fixed. Two sets of electrically insulated electrical conductors or wires extend ftom the circuit board 2. A first set comprises two supply wires 3, 3', and signal wires 4, 4'. A second set comprises two conductors or wires 103, 103' for connection to the brush-holder of an associated direct-current electric motor.

9 These sets of electrical wires extend through respective grommets or blocks, indicated 60 and 61 in Figure 13.

In contrast with the embodiments described above, each of the grommets 60 and 61 is formed in a single piece. One of these grommets, indicated 6 1, can be seen in greater detail in Figures 14 to 16. As can be seen in these drawings, each grommet or block comprises a body 62 of moulded plastics material with two opposed, aligned, tubular projections 63 and 64.

A longitudinal duct 65 extends through the body 62 and also extends into the tubular projections 63 and 64 thereof.

A further duct 66 also extends through the body 62 and intersects the above-mentioned duct substantially perpendicularly.

The wires associated with each grommet extend through the duct 65 and through their tubular appendages 63, 64.

As can be seen in particular in Figure 13, two slots 21 and 121 are formed in the side wall of the metal container 10. Two substantially parallelepipedal, open-topped seats 22, 122 are formed in the container 10, adjacent the slots 21 and 121. The side wall of each of these seats disposed facing the respective slot 21, 121 has a corresponding slot 70, 170.

During assembly, the grommets 60 and 61 are placed in the associated seats 22 and 122 in the metal container 10 in a manner such that the respective tubular end appendages extend through the facing slots 21, 70 and 121, 170, respectively.

After the circuit board 2 has been positioned in the metal container 10 and the grommets 60 and 61 have been positioned in the respective seats 22, 122, the circuit board 2 is fixed to the container 10 by means of screws, substantially as indicated in Figure 13.

Upon completion of this operation, a cover 40, preferably made of metal, the outline of which corresponds to the profile of the mouth of the metal container 10, is associated therewith.

It will be noted in particular that two holes, indicated 80 and 180 in Figure 13, are formed in the cover 40, in positions such that they face the vertical ducts 66 formed in the grommets.

After the cover 40 has been correctly fitted on the container 10, the spaces defined between the periphery of the cover and the upper edge of the metal container 10 are sealed. This sealing step is performed by the injection of a setting sealant material.

The spaces defined in the ducts 66 of the grommets, between the grommets and the wires which extend through them, are also sealed by injection of this material. This sealing step is performed through the holes 80 and 180 in the cover 40 which allow thin needles for the injection of the sealant to be introduced into the ducts 66.

Upon completion of the sealing step, the region between the cover and the metal container is sealed from the outside environment in a leaktight manner.

Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.

Claims 1. An electronic speed regulator (1) for an electric motor, particularly for a fan associated with a heat exchanger, comprising, in combination: at least one circuit board (2) from which a plurality of insulated electrical wires (3, Y; 4, 4; 103, lOY) extend, a substantially dish-shaped metal container (10) in which the circuit board (2) is fitted and which has at least one slot or opening (21; 121) through which the electrical wires can extend, a seat (22; 122) being formed in the container (10), adjacent the slot or opening (21; 121), at least one grommet or block (25, 45; 60, 61) of electrically insulating material, through which the wires extend and which can be fitted at least partially in the seat (22; 122) in the container (10), the grommet (25, 45; 60, 6 1) having at least one internal duct (51, 52, 32, 33; 66) which, after the positioning of the grommet in the seat (22, 122), permits the injection of a setting sealant material for sealing the spaces between the wires (3, Y, 4, 4', 103, 103) and the grommet (25, 45; 60, 61) in a leaktight manner, and a cover (40) fitted on the container (10) over the circuit board (2), the spaces between the cover (40), the container (10), and the at least one grommet (2 5, 45; 60, 61) being sealed in a leaktight manner by means of a setting sealant.

2. A regulator according to Claim 1 in which the cover (40) is made of electrically insulating material and the at least one grommet is formed in two complementary parts (25, 45), of which one (25) can be pre-fitted in the associated seat (22) in the metal container (10) and the other (45) is formed integrally with the cover (40).

3. A regulator according to Claim 1 or Claim 2 in which the grommet (25, 45) has external channels or recesses (34-38) which communicate with the at least one duct (51, 52, 32, 33), face the walls of the seat (22), and are intended to be filled with the sealant material.

12 4. A regulator according to any one of the preceding claims, for a direct- current electric motor provided with brushes, in which electrical connection terminals (43) are fixed to the circuit board (2) and extend through corresponding slots (49) in the cover (40), the spaces between the terminals (43) and the corresponding slots (49) in the cover (40) being sealed in a leaktight manner by the injection of setting sealant material.

5. A regulator according to Claim 1 in which the at least one grommet (60, 6 1) comprises a body (62) of electrically insulating material in which there are a first duct (63-65) for the electrical wires, and a second duct (66) which intersects the first duct (63-65) and is accessible from the exterior after the grommet (60, 61) has been fitted in its seat (22, 122) in the metal container (10) to permit the injection of setting sealant material into the spaces between the wires (103, lOY) and the grommet (60, 61).

6. A regulator according to Claim 5 in which the cover (40) has at least one edge portion disposed over the at least one grommet (60, 61) and having a hole (80, 180) facing the second duct (66) of the grommet (60, 61) to permit the injection of sealant material into the grommet.

7. A method for the production of an electronic speed regulator (1) for an electric motor, particularly for a fan associated with a heat exchanger, comprising the steps of. providing at least one circuit board (2) from which a plurality of insulated electrical wires (3, Y, 4, 4'; 103, lOY) extend, providing a substantially dish-shaped metal container (10) having at least one slot or opening (2 1; 12 1) and at least one internal seat (22; 122) adjacent the slot or opening (21; 121), providing at least one grommet (25, 45; 60, 61) of electrically insulating material which can be fitted at least partially in the seat (22; 122) in the container (10) and through which the wires can extend, the grommet having at least one internal duct (51, 52, 32, 33; 66) communicating with the region of the grommet through which the wires are to extend, providing a cover (40) of a shape substantially corresponding to that of the mouth of 13 the container (10), fitting the circuit board (2) in the container (10) and the at least one grommet (25, 45; 60, 6 1) in the corresponding seat (22; 122) in the container (10), with the wires extending through the grommets, fitting the cover (40) on the container (10), and injecting a setting sealant material into the spaces between the cover (40), the container (10), and the grommet (25, 45; 60, 6 1), as well as into the at least one duct (51, 52, 32, 3 3; 66) in the grommet, so that the region between the cover (40) and the container (10) is rendered leaktight.