AU658691B2

AU658691B2 - Warning light for motor vehicles

Info

Publication number: AU658691B2
Application number: AU28442/92A
Authority: AU
Inventors: Herbert Fuchtjohann; Kurt Morchen; Burkhard Schmidt; Franz-Josef Schreckenberg
Original assignee: Hella KGaA Huek and Co
Current assignee: Hella GmbH and Co KGaA
Priority date: 1991-12-11
Filing date: 1992-11-18
Publication date: 1995-04-27
Anticipated expiration: 2012-11-18
Also published as: EP0546290A2; AU2844292A; EP0546290B1; CZ360092A3; CZ280263B6; DE59207122D1; ES2091380T3; SG42383A1; EP0546290A3; DE4140821C1

Description

*1 658691

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDAR.D PATENT

.#C

it it A ii 04 C o *4 U CO Applicant(s): HELLA KG HUECK CO.

Invention Title: WARNING LIGHT FOR MOTOR VEHICLES C C The following statement is a full description of this invention, including the best method of performing it knownj to me/us: .4.4 r 4 (1(44 CC CC -2- The present invention relates to a warning light for motor vehicles, having a transparent covering hood, which is fitted over a light base, with an incandescent bulb located within the covering hood, a rotatable reflector located within the covering hood and with a drive mechanism located within the covering hood for rotating the reflector, which is non-rotatably connected to the light base.

This type of warning light is already known from the German Patent DE-PS 39 761 and is utilised, for example, on privileged right-of-way vehicles, such as police and fire brigade vehicles, for transmitting optical signals. These alreadyknown warning lights possess a high speed electric direct-current motor as the drive mechanism, with mechanical commutation by way of a collector. For decreasing the high speed of rotation to the desired number of r.p.m. of the reflector, a toothed gear-wheel mechanism is provided in the already-known warning light.

15 These already-known warning lights have disadvantages. Because of the use of a collector as the mechanically commutating element, the motor driven by direct current used in the already-known warning lights is subjected to a great deal of S wear-and-tear, thus imposing limits on the operating life of the drive motor and therewith of the entire already-known warning light. The reduction gear used to decrease the high speed of rotation to a lower speed of rotation of the reflector is rendered very expensive because of the additional components required, not only for its fabrication, but also for its installation, thus greatly increasing the cost of the warning light. In addition, these additional components of the drive mechanism are likewise subjected to wear-and-tear, which can lead to a decrease of the operating life and functional breakdowns of the already-known warning light. On top of all this, additional space is required within the transparent covering hood, or within the light base, for accommodating the gear

I

8 i i d 6 !1 ii i 1

Y

-3components, thus increasing the overall size required for the already-known warning light. This increase in the construction space may also be influenced by the choice of the drive mechanism such as, for example, in the already-known lights by the choice of a worm gear which must be located on the axis of the drive motor at right angles to the axis of rotation of the reflector.

In addition to this, these types of mechanically commutating direct-current motors and the gears required cause vibrations and noises, so the warning lights may seem very loud when in operation. On the basis of the brush sparks generated by the mechanical commutation, these types of direct-current electric motors give rise to electro-magnetic interference fields, which, in particular in the utilisation of these types of warning lights on motor vehicles, can cause interference with other electrical devices of the motor vehicle such as, for example, active and passive radio-frequency radio installations.

Furthermore, this type of mechanically commutating direct-current electric motors are always designed for specific operating voltages, so that, for a given Si operating voltage, the choice of the desired rate of rotation of the reflector must be taken in account during the construction. Subsequent alterations of this rate of rotation of the reflector can only be made possible, at great expense, by the selection of other direct-current electric motors or by alteration of the reduction 20 gearing. In particular, for the use of already-known warning lights in different S on-board voltage supply networks, such as, for example, 12 volt and 24 volt networks, various deviations from the already-known warning lights are required, thus making it expensive to keep all the parts in stock for all these different warning lights.

The problem to be solved by the invention is how to provide a warning light for motor vehicles which has a simpler and less expensive construction compared -4with the already-known warning lights and which will have a longer operating life.

This problem may be solved, in accordance with the present invention, by having an electric motor without a commutator and without reduction gearing, and by having the rotor of the motor mounted around the outside of the stator.

Because of the employment of a motor without a commutator, in the warning light in accordance with the present invention, it is possible to increase the length of its operating life compared with that of already-known warning lights, because, as a difference from the already-known warning lights, there can be no wear-and-tear on the mechanical commutator. In addition, in motors without a collector and electronically commutated, the rate of rotation may be adjusted practically independently of the operating voltage, so that the warning light in S. accordance with the present invention, for operation in different on-board voltage supply systems, may be used without alteration of the mechanical construction. Furthermore, the regulation of the rate of rotation of the motor without a collector, and therewith the regulation of the rate of rotation of the reflector can only be made possible by acting upon the electronics which regulate the commutation, without alteration of the mechanical construction.

Because of tha fact that, with electronic commutation of the motor without a collector, the desired rate of rotation may be adjusted to almost any arbitrary value, by the appropriate selection of the electronic components, for the warning light in accordance with the present invention, it is possible to dispense with the use of gearing between the motor without a collector and the rotatable reflector, so that this results in the direct driving of the rotatable reflector. By means of this inventive direct drive, all of the disadvantages, already referred to, which are associated with mechanical gearing are avoided. In particular, because

F,-

of the direct drive, the actual physical size of the inventive warning light, the amount of noise generated and the length of its operating life are substantially improved when compared with already-known warning lights.

In order to achieve the usually desired low rate of rotation of the rotating reflector, and thus of the drive motor without a collector and without mechanical gearing, with the greatest possible uniformity of rotary movement of the reflector without jerkiness, provision is made by the invention to have the rotor of the electric motor mounted around the outside of the stator. Because of this inventive measure, the torque of the motor without a collector is made as great as possible, since the moving mass of the rotor is at the greatest possible distance away from the axis of rotation. On the basis of the correspondingly great inertial mass, the motor without a collector rotates smoothly, even at low rates of revolution.

o Because of the electronic activation of the direct-current motor without a collector, it is additionally possible to have synchronisation of a plurality of S* inventive warning lights driven by motors without collectors. Furthermore, it is possible to monitor the rotation of the reflector and the braking of the reflector when the warning light is switched off, electronically with the use of simple equipment.

:20 Advantageous embodiments and further developments of the inventive warning d ei light are set down in the dependent Patent Claims.

It is especially advantageous for the stator to be non-rotatably connected to the light base, so that the rotating arrangement, comprising the rotatable reflector i and the rotor, right up to the rotary movement, is fixed as securely as possible in the housing, comprising the transparent covering hood and the light base.

i -6- However, in order to prevent the transmission of vibrations between the stator and the light base, in this connection it is advantageous for the stator to be connected to the light base with vibration-damping, in particular by means of rubber buffers.

In this connection, with the objective of additional reduction of the construction costs and for further reduction of the height of the inventive warning light, the stator, at least in part, should be integrally fabricated with the light base by injection moulding, in particular from synthetic plastics material. This possibility makes it different from the already-known lights, because the drive and the combined rotating reflector give rise to practically no vibration in the inventive o warning light.

6 The stator may advantageously have the motor windings, in which case the windings are disposed on the collar of a base plate. The required motor windings may advantageously be wound directly onto the collar. In this connection, the base plate may be a printed-circuit board with the electronic components for electronic commutation of the motor without a collector. This results in an advantageous structural incorporation of the motor windings with the printed-circuit board, which requires only very short conductor connections

I

between these two components and avoids the loss of electrical energy.

:20 The rotor may then advantageously include the permanent magnets, in which case, on the basis of the proposed direct drive, the reflector may be connected non-rotatably to the rotor. In the already-known warning lights, the incandescent bulb is kept stationary. There are also warning lights in which the incandescent bulb rotates with the reflector. In this case, in this connection, it is especially advantageous for the incandescent bulb to be non-rotatably connected to the rotor just as the reflector is.

i. -7- To make possible the easy rotation of the reflector, it is especially advantageous for the rotor to be fitted with bearings which are rotatably mounted on a sleeve which is non-rotatably affixed to the base plate. For the bearing here it is equally possible to use a slide bearing, or else needle or ball bearings. In this connection, in order to establish the electrical connection between the incandescent bulb and the connection terminals, it is especially advantageous for the sleeve to be electrically conducting and connected, on the one side, to the incandescent bulb and, on the other side, with the electrical connection terminals.

Likewise, for electrical connection of the incandescent bulb, it is possible to S. arrange for an electrical conductor to be insulated within the sleeve by means of a guide component, in particular where the conductor is a screw-threaded bolt which, on the one side, is connected with the incandescent bulb and, on the other side, with an additional electrical connection terminal. In particular, in the embodiment of the electrical conductor as a bolt, if necessary the bolt, in common with the other components, may be used for fixing the rotor and stator :r axially in relation to one another.

T This type of fixing is also made possible by having the rotor axially fixed on the Ssleeve by means of a disk. Especially then, when the incandescent bulb also rotates, it is particularly advantageous to provide a slide contact for electrical connection of the sleeve and the conductor with the incandescent bulb.

Examples of embodiment of the warning light in accordance with the present invention will now be described in greater detail, with reference to the accompanying drawings, in which: -8- Fig. 1 is a part section through a warning light in accordance with the present invention, having a vibration-decoupled base plate, Fig. 2 is a plan view from above of the rotor and the base plate of the warning light as depicted in Fig. 1, and Fig. 3 is a warning light in accordance with the present invention, with integrated embodiment of the base plate in common with the light base and with a tube connection terminal for fastening the inventive warning light in position.

As shown in Fig. 1, a transparent covering hood is connected detachably, by means of a bayonet coupling, to the light base The entire inventive warning 10 light as depicted in Fig. 1 may be fastened to a support on a motor vehicle, for example with the use of screws, and the interposition of a rubber packing disk Within the covering hood there is a rotatable reflector which is fastened to the rotor (12) of a direct-current motor without a collector. The reflector is :15 provided with an opening for insertion of an incandescent bulb, which is not depicted in the Figures.

Also located within the transparent covering hood there is a base plate which, by means of rubber buffers for vibration damping, and screws is affixed to the light base The rubber buffers are inserted into eyes in the base plate The base plate carries, on its underside, a printed-circuit board on which P are located the electric components (not depicted) for electronic commutation of the direct-current motor without a collector. On the side of the base plate 9 facing away from the printed-circuit board there is a collar (10) around which the motor armature windings (11) of the direct-current motor without a collector are wound.

The motor armature windings (11) may advantageously be wound directly onto this collar The rotor (12) carries permanent magnets (13) around its circumference, the magnetic fields of which, depending upon the supply of current, correspond to the motor armature windings (11) and lead to rotation of the rotor (12) relative to the motor armature windings (11) which form the stator of the direct-current motor without a collector.

In order to make possible the easy rotation of the rotor (12) relative to the motor armature windings said 0 rotor (12) is furnished with a bearing (14) which is mounted rotatably on an electrically-conducting sleeve Inside the sleeve and insulated by means of an insertion guide member there is a hexagonal bolt So which is also capable of conducting electricity.

Furthermore, between the insertion guide member (17) and the rotor a disk (18) is provided for the fixing of 0o 0 •the rotor (12) in relation to the motor armature windings and this disk is connected in an electrically- S-conducting manner to the sleeve The sleeve (15) as well as the hexagonal bolt (16) are provided at their lower ends with flat cable plugs (20) which also project through the printed-circuit board where they may be electrically connected to the conducting tracks which are located on this printed-circuit board Not only on the disk but also on the hexagonal head of the hexagonal bolt there are slide contacts (19) present which are connected to the electrical terminal connections of the incandescent bulb, in order to make possible the lighting-up of the incandescent bulb c 1 i ~1 In Fig. 2, the same or similarly-acting components are designated with the same reference numbers as in Fig. 1. In this Figure the fundamental shape of the base plate ma be recognised, which has a total of three eyes into which the rubber buffers may be inserted. In addition, it may also be seen that the rotor (12) has, on its upper side, means for the fastening thereto of the reflector and that there are means for holding the incandescent bulb.

The inventive warning light as depicted in Figs. 1 and 2 functions in the following manner: As soon as voltage is applied to the flat cable plugs then the incandescent bulb (not depicted) is switched on and emits light. However, with the switchingon of the incandescent bulb, the electronic circuitry present on the printedcircuit board is supplied with current, which starts the process of electronic commutation of the direct-current motor without a collector, in which the motor SA windings (11) receive a supply of current in a prescribed phase position. As soon as this happens, an electro-magnetic field is established between the permanent Smts amtur Sit magnets (13) and the motor~windings leading to the production of a rotary force which is effective between the rotor (12) and the motor windings On the basis of the freely rotating bearing of the rotor (12) on the sleeve (15) by way of the bearing the rotor (12) is caused to rotate in relation to the motor windings (11) by the action of this force. Because not only the incandescent bulb (not depicted), but also the reflector is non-rotatably affixed to the rotor (12), the reflector is rotated in common with the rotor (12) to produce the wellknown signal effect of such warning lights. This rotation of the reflector is maintained for just as long as voltage is applied to the flat cable plugs As soon as the voltage supply to the flat plugs (20) is interrupted, the light of the incandescent bulb is extinguished, and the rotor (12) in common with the reflector ceases its rotary movement.

V L U 2 Pii -11- In Fig. 3, the same or similarly-acting components are designated with the same reference numbers as in Figs. 1 and 2. The difference here from the warning light depicted in Fig. 1 is that the base plate is injection moulded integrally with the light base This structural solution is possible with the warning light in accordance with the present invention for the reason that the entire rotatable arrangement, comprising the rotor the permanent magnets the bearing (14) the reflector and the incandescent bulb, generates practically no vibration which could be transmitted to the remaining parts of the warning light in accordance with the present invention. This being the case, the warning light as depicted in Fig. 3 has the particular advantage that the construction, compared with the solution presented in Fig. 1, is structurally much simpler. In particular the eyes the rubber buffers and the fixing screws all of which can contribute appreciably to the cost, especially of the assemb!v operations, are no longer necessary. An additional advantage of the warning '15 light, as depicted in Fig. 3, is that the warning light, comprising the covering hood and the light base is smaller in height than the embodiment sho-;,:i in Fig. 1.

SC Since the direct-current motor without a collector which is used in accordance with the present invention has a length of operating life approximately the same as that of the rest of the components of the warning light, any possible replacement of components of the warning light, such as may be required with the embodiment as shown in Fig. 1, is not unconditionally necessary.

In addition, in the warning light depicted in Fig. 3, a short tube connector (21) is provided, and this may be used if the warning light in accordance with the present invention is not to be mounted on a flat, smooth, support surface, but is i to be affixed to one end of a pipe.

K:

I

Claims

41. Warning light for motor vehicles, having a Y4 transparent covering hood, which is fitted over a light base, with an incandescent bulb located within the covering hood, a rotatable reflector located within the covering hood, and with a drive mechanism located within the covering hood for rotating the reflector, which is non- rotatably connected to the light base, wherein the drive comprises a motor without a collector and without gearing, wherein 4 ie- rotor of the motor is mounted around the outside of th1e- stator windings, wherein the- stator windings are non-rotatably connected to the light base, wherein 4 Ae stator has motor armature windings and wherein the rotor includes permanent magnets and wherein the reflector is non-rotatably connected to the rotor. 4, 1'r 2. The warning light according to Claim 1, wherein the stator windings are connected to the light base with vibration-damping, in particular by means of rubber buffers. 3. The warning light according to Claim 1, wherein the stator, at least partly, is integrally fabricated with the light base by injection moulding, in particular from 4 synthetic plastics material. 4. The warning light according to Claim 1, wherein the motor armature windings are disposed on a collar of a base plate. The warning light according to Claim 4, wherein the base plate carries'a printed-circuit board with the electronic components for electronic commutation of the motor. I'6. The warning light according to Claim 1, wherein 13 the incandescent bulb is non-rotatably affixed to the rotor. 7. The warning light according to Claim 4, wherein the rotor is fitted with a bearing which is rotatably mounted on a sleeve which is non-rotatably affixed to the base plate. 8. The warning light according to Claim 7, wherein the sleeve is electrically-conducting and, on the one side, is connected to the incandescent bulb and, on the other side, is connected to an electrical terminal cable plug. 9. The warning light according to Claim 8, wherein, inside the sleeve, and insulated by means of an insertion guide member, there is an electrical conductor, in particular a bolt which, on the one side is connected to the incandescent bulb, and on the other side, is connected to an additional electrical terminal cable plug. Sti The warning light according to Claim 9, wherein the rotor is axially fixed on the sleeve by means of a disk and wherein slide contacts are provided for electrical 20 connection of the sleeve and the conductor with the incandescent bulb. DATED THIS 13TH DAY OF JANUARY 1995 HELLA KG HUECK CO By Its Patent Attorneys GRIFFITH HACK CO Fellows Institute of Patent Attorneys of Australia I ABSTRACT Warning light for motor vehicles In a warning light for motor vehicles, having a transparent covering hood which is fitted over a light base with an incandescent bulb located within the covering hood a rotatable reflector located within the covering hood (1) and with a drive mechanism located within the covering hood for rotating the reflector which is non-rotatably connected to the light base the driving means, in order to increase the length of its operating life and for simplification and cheapening of the construction, comprises a motor without a collector and without mechanical gearing. In this design, the rotor (12) of the S.i motor is mounted around the outside of the stator (motor windings 11). r C II c c -1