Title of Invention

A CONTACT DISC SYSTEM OF A WINDSCREEN WIPER MOTOR

Abstract

ABSTRACT '*A contact disc system of a windscreen wiper motor" The invention relates to a contact disc system having a rotatable contact disc (10) and a plurality of contact elements (12, 14, 16, 18), the contact disc (10) having a plurality of tracks (20, 22) and each contact element (12, 14 16, 18) being assigned to a track (20, 22) wherein the contact disc (10) has two tracks (20, 22) and wherein two selected contact elements (12, 14) of the plurality of contact elements (12, 14, 16, 18) are always at the same electrical potential and slide on the same track (20). The invention furthermore relates to a windscreen wiper motor. (Figure 11)

Full Text

The invention relates to a contact disc system of a windscreen wiper motor. The contact disc system having a rotatable contact disc and a plurality of contact elements, the contact disc having a plurality of tracks and each contact element being assigned to a track. The invention furthermore relates to a method for controlling a windscreen wiper motor using a contact disc system having a rotatable contact disc and a plurality of contact elements, the contact disc having a plurality of tracks and each contact element being assigned to a track. Furthermore the invention relates to a windscreen wiper motor comprising a contact disc system having a rotatable contact disc and a plurality of contact elements, the contact disc having a plurality of tracks and each contact element being assigned to a track. Prior art Windscreen wiper apparatuses with contact disc systems of the generic type and methods of the generic type for controlling windscreen wiper motors are known in particular for cleaning motor vehicle windscreens. The windscreen wiper apparatuses are usually operated by a switch situated in the interior of the motor vehicle, this switch usually being designed as a steering column switch. By changing over the steering column switch, the windscreen wiper apparatus can be transferred from a switched-off state into at least one operating state. Operating states with a plurality of windscreen wiper speeds and an intermittent circuit are usually realized. In order to ensure that, after being switched off by the steering column switch, the windscreen wipers do not stay in an intermediate position but rather are transferred properly into the parked position, it is known to use contact disc systems. Such contact disc systems maintain a closed electric circuit, in which the windscreen wiper motor is situated, until the windscreen wipers have reached the parked position. Figure 1 illustrates a contact disc 110, which is used in a contact disc system of the prior art. A contact disc 110 of this type is installed in windscreen wiper motors of the generic type in such a way that it rotates synchronously with the windscreen wiper motor. The contact disc 110 establishes a contact with three contact elements which each slide on a track of the contact disc 110. A first contact element slides on the outer track 12 0, which has an interruption. A second contact element slides on the inner track 122, which is realized as a short track, and a third contact element slides on a middle track 121, which is continuous. A construction of this type enables a current flow to be maintained in all motor positions, except in the end position and in a region of proximity to the end position. This is achieved by virtue of the fact that a contact element which is connected to the positive pole of the battery slides on the outer track 120. A contact element which slides on the middle track 121 is connected to the wiper motor. A current flow from the positive pole of the battery to the wiper motor is thus possible for as long as the first contact element slides on a conductive region of the outer track 120. Only when the contact disc 110 has rotated to an extent such that the contact element is situated in the interruption of the outer track 120 is the current flow interrupted. On account of the inertia of the motor, the contact disc then still rotates further despite the interrupted current flow. However, this further rotation is ended when the conductive region of the short inner track 122 is connected to a contact element. This contact element is connected in such a way that the motor is short-circuited and is actively braked in this way. On account of che three tracks of the contact disc of the prior art, the said contact disc has a certain minimum structural size. In the case of windscreen wiper motors, however, endeavours are made to achieve a smallest possible overall structural size, that is to say, in particular, also a smaller size of the contact disc. A smaller size of the contact disc would furthermore have advantages in the production of windscreen wiper motors, in particular in the case of rear wiper motors with reciprocating gear mechanism, where it is currently necessary to fit the contact disc with the contact-making on the opposite side with regard to the reciprocating gear mechanism. For this reason, the windscreen wiper motor currently has to be rotated during assembly on the assembly line, which complicates the production process. Advantages of the invention The invention builds on the contact disc system of the generic type by virtue of the fact that the contact disc has two tracks and in that two selected contact elements of the plurality of contact elements are always at the same electrical potential and slide on the same track. In this way, it is possible even with a two-track contact disc to maintain an electric current flow until the parked position of the windscreen wipers has been reached or until shortly before the parked position has been reached. By virtue of the fact that the contact disc manages with two tracks, it has a smaller structural size or radial structural width, which entails advantages with regard to the overall structural size of the windscreen wiper motor and with regard to the manufacturing process. Preferably, the selected contact elements slide on a first track, which has an electrically conductive region and an electrically insulating region, and at least one contact element of the selected contact elements is connected to the electrically conductive region. If the windscreen wiper motor is switched off by changeover of the steering column switch, then an electrical connection to the wiper motor is maintained via at least one of the selected contact elements, since at least one of the selected contact elements is always connected to the electrically conductive region of the first track. Preferably, the electrically insulating region of the first track is realized by an interruption of a conductive track and the selected contact elements have a spacing which is greater than the interruption of the first track. In the case of a circular contact disc, the electrically insulating region can consequently be realized by a cutout with boundaries running radially. If the aperture angle of this interruption is smaller than the spacing angle of the selected contact elements, then this ensures that one of the:-'■selected-contact elements is always connected to the electrically conductive region of the first track. It is particularly preferred if a first further contact element slides on the first track. This first further contact element serves for maintaining an electrical connection between the contact disc and the positive pole of the vehicle battery. Consequently, even when the steering column switch is in the switched-off position, an electrical connection is maintained via the first further contact element and at least one of the selected contact elements between the positive pole of the battery and the motor. Only when the first further contact element leaves the electrically conductive region of the first track and is situated in the insulating region of the first track is the current flow interrupted. It is particularly advantageous if a second track has an electrically insulating region and an electrically conductive region and a second further contact element slides on the second track. This contact element serves for realizing an electrical short circuit of the motor and for thereby actively braking the motor when the parked position is reached. Preferably, the interruption of the first track, the electrically conductive region of the second track, the first further contact element and the second further contact element are arranged with respect to one another in such a way that a state exists in which neither the first further contact element nor the second further contact element are connected to an electrically conductive region of the first track and of the second track, respectively. Although the current flow in the electric circuit of the windscreen wiper motor is already interrupted in this state, the motor and the contact disc nevertheless still rotate further on account of their inertia. The rotational speed of the motor decreases during this phase, and only when the second further contact element is connected to the electrically conductive region of the second track does active deceleration of the motor take place on account of the electrical short circuit. It is particularly beneficial if the angular range which is covered by the electrically conductive region of the second track is smaller than the angular range which is covered by the electrically insulating region of the first track. As a result of this, it is possible that, on account of the rotation of the contact disc, the first further contact element has already left the conductive region of the first track, while the second further contact element has not yet reached the conductive region of the second track. In this intermediate state, then, the motor is neither driven nor actively decelerated. The motor rotates further on account of its inertia, although the rotational speed decreases. Only when the electrically conductive region of the second track is connected to the second further contact element is the motor finally braked. The contact elements are preferably contact springs. A reliable contact between the contact disc and the contact elements is established in this way. The invention builds on the method of the generic type by virtue of the fact that a contact disc system according to the invention is used for controlling a windscreen wiper motor. In this way, the advantages of the contact disc system according to the invention are implemented by a control method. It is particularly advantageous if, in the method according to the invention, a switch connected to the contact disc system is changed over and a rotation of the contact disc is maintained until the second further contact element is connected to the electrically conductive region of the second track. The control method thus advantageously enables the windscreen wipers to be reliably transferred from an operating position to a parked position. In this case, it is particularly advantageous if, before the connection of the second further contact element to the electrically conductive region of the second track, the connection of the first further contact element to the electrically conductive region of the first track is interrupted. During the intermediate state thus produced, although the electrical connection of the motor and the battery is already interrupted, rotation still takes place on account of the inertia of the components involved, although the rotational speed of the motor slows down. Only when the second further contact element comes into contact with the electrically conductive region of the second track is the motor actively decelerated. The invention builds on the windscreen wiper motor of the generic type by virtue of the fact that it has a contact disc according to the invention. As a result, the windscreen wiper motor implements all the advantages of the contact disc according to the invention and of the method according to the invention. It is particularly advantageous that a windscreen wiper motor with a reduced structural size can be produced. The invention is based on the surprising insight that, on account of a suitable arrangement of contact elements and a suitable geometrical configuration of a contact disc, it is possible for the functions of a three-track contact disc, as is used in windscreen wiper motors of the prior art, also to be made possible using a two-track contact disc. Therefore, windscreen wiper motors according to the invention can be produced with a smaller structural size. In particular, the manufacturing process can be simplified since it is no longer necessary to rotate the motor on the workplace carriers of the assembly line. Drawings The invention will now be explained by way of example using preferred embodiments with reference to the accompanying drawings. In the figures: Figure 1 shows a contact disc of the prior art; Figure 2 shows a contact disc system according to the invention; Figure 3 shows an electrical circuit with a contact disc system according to the invention in a switched-on state; Figure 4 shows an equivalent circuit diagram of the circuit in accordance with Figure 3; Figure 5 shows an electrical circuit with a contact disc system according to the invention in a first intermediate state; Figure 6 shows an electrical circuit with a contact disc system according to the invention in a second intermediate state; Figure 7 shows an electrical circuit of a contact disc system according to the invention in a third intermediate state; Figure 8 shows an equivalent circuit diagram of the circuits in accordance with Figures 5 to 7; Figure 9 shows an electrical circuit with a contact disc system according to the invention in a fourth intermediate state; Figure 10 shows an equivalent circuit diagram of the circuit in accordance with Figure 9; Figure 11 shows an electrical circuit with a contact disc system according to the invention in a switched-off state; and Figure 12 shows an equivalent circuit diagram of the circuit in accordance with Figure 11. Description of the exemplary embodiments In the following description of the drawings, identical elements are identified by identical reference symbols. Figure 2 shows a contact disc system according to the invention in a plan view. The contact disc system comprises a contact disc 10 and a plurality of contact elements 12, 14, 15, 18. The contact elements 12, 14, 16, 18 are designed as contact springs. The contact disc 10 has two tracks 20, 22. The first track 20 has a relatively long electrically conductive region 24 and a comparatively short electrically insulating region 26, which is realized by an interruption of the track 20. The first track 20 lies outside the second track 22 in the radial direction. This second track 22 has a relatively long electrically insulating region 28 and a comparatively short electrically conductive region 30. The electrically conductive region 30 is realized as a short attachment piece on the electrically conductive region 24 of the first track 20. Two contact elements 12, 14 of the plurality of contact elements 12, 14, 16, 18, which are designated as selected contact elements 12, 14, have a spacing angle with regard to their contact points 36, 3 8 which is larger than the interruption 26 of the first track 20. In this way, at least one of the contact elements 12, 14 is always connected to the electrically conductive region 24 of the first track 20. The first further contact element 16 slides on the first track 20. The second further contact element 18 slides on the second track 22. The angular range which is covered by the interruption 2 6 of the first track 20 is larger than the angular range which is covered by the electrically conductive region 30 of the second track. The contact point 40 of the first further contact element 16 and the contact point 42 of the second further contact element 18 and also the interruption 26 of the first track 20 and the electrically conductive region 30 of the second track 22 are arranged with respect to one another in such a way that there is a state in which neither the first further contact element 16 nor the second further contact element 18 are connected to their respective tracks. Likewise, the arrangement of the first further contact element 16 and of the second further contact element 18 and of the interruption 2 6 of the first track 2 0 and of the electrically conductive region 3 0 of the second track 22 is chosen in such a way that a state exists in which the second further contact element 18 is connected to the electrically conductive region 3 0 of the second track 22, while the first further contact element 16 lies in the electrically insulating region 26 of the first track 20 and thus has no electrical contact with the contact disc 10. Figure 3 shows an electrical circuit with a contact disc system according to the invention in a switched-on state. A switch 34, which is generally designed as a steering column switch, establishes a connection between the terminal 5 3 and the positive pole of the vehicle battery. In this way, the positive potential is present at the motor 32 via the terminal 53, a polarity-reversal protection diode 44 and a coil 46. This is independent of the position of the contact disc 10 with regard to the contact elements 12, 14, 16, 18, an arbitrary snapshot of the contact disc 10 which rotates synchronously with the motor 32 being represented in the present case. Figure 4 shows an equivalent circuit diagram of the circuit in accordance with Figure 3. The illustration shows that the terminal 53 is always at positive potential via the switch 34. The contact disc 10, which is symbolized by a switch actuated by the motor 32, alternates between a plurality of switching states, an additional connection between the motor 32 and the positive pole via the terminal 53a existing at certain times. This is symbolized by the solid line in the symbolic representation of the contact disc 10. An additional connection between the motor 32 and the terminal 53 is provided at other times. This is shown by the right-hand interrupted line of the symbolic representation of the contact disc 10. Likewise, there is a state in which the contact disc 10 establishes no further connection between the motor 32 and one of the terminals 53, 53a, which is illustrated by the middle interrupted line of the symbolically represented contact disc 10. Independently of the switching states of the contact disc 10, in the switched-on state, that is to say in the state in which the switch 34 establishes a connection to the positive pole, a positive potential is present at the motor 32 via the coil 46. Figure 5 shows an electrical circuit with a contact disc system according to the invention in a first intermediate state. In order to switch off the windscreen wiper, the switch 34 has been changed over, so that now there is a connection to the negative pole of the battery through the switch 34. However, the positive potential is still fed to the motor 32 via the terminal 53a, the contact element 16, the contact disc 10 and the contact element 12. In the snapshot illustrated in Figure 5, the contact element 14 is situated in the electrically insulating region of the first track 20 of the contact disc 10. Since the spacing between the selected contact elements 12, 14 is larger than the interruption 26 of the first track 20 of the contact element 10, a connection from the contact disc 10 to the motor 32 is always maintained. The second further contact element 18, which is at negative potential via the terminal 53, is not always connected to the contact disc since it is situated in the electrically insulating region of the second track 22. Figure 6 shows an electrical circuit with a contact disc system according to the invention in a second intermediate state. This second intermediate state corresponds to the first intermediate state in accordance with Figure 5, apart from the fact that the contact of the positive pole is now established via the other selected contact element 14. Figure 7 shows an electrical circuit with a contact disc system according to the invention in a third intermediate state. This third intermediate state also corresponds to the first intermediate state in accordance with Figure 5 and the second intermediate state in accordance with Figure 6, except that the connection between the positive pole and the motor 32 is maintained by both selected contact elements 12, 14 in the snapshot in accordance with Figure 7. Figure 8 shows an equivalent circuit diagram of the circuits in accordance with Figures 5 to 7 . In all states, the positive pole is connected to the motor via the terminal 53a, so that the operation of the said motor is maintained. Figure 9 shows an electrical circuit with a contact disc system according to the invention in a fourth intermediate state. This fourth intermediate state differs electrically from the first intermediate state, the second intermediate state and the third intermediate state. In the fourth intermediate state in accordance with Figure 9, the first further contact element 16 is situated in the electrically insulating region 26 of the first track 20. Therefore, the positive potential is no longer present at the selected contact elements 12, 14, with the result that voltage is no longer present at the motor 32 either. The second further contact element 18 is situated in the electrically insulating region of the second track 22, but just before making contact with the electrically conductive region. Proceeding from the state in accordance with Figure 9, the contact disc is rotated further on account of the inertia of the components involved. Figure 10 shows an equivalent circuit diagram of the circuit in accordance with Figure 9. The illustration shows that neither the terminal 53a nor the terminal 53 are connected to the motor. This means that there is neither a positive potential present for the normal operation of the motor 32, nor, likewise, is there a negative potential present at the motor 32, which would short-circuit the motor 32. Figure 11 shows an electrical circuit with a contact disc system according to the invention in a switched-off state. In a manner corresponding to Figure 9, the contact element 16 is situated in the electrically insulating region 26 of the track 20 in this case as well. Unlike in Figure 9, however, the contact element 18 is situated in the electrically conductive region 30 of the second track 22 in the snapshot in accordance with Figure 11. Consequently, there is a connection between the negative pole and the motor via the terminal 53 and the contact element 18. The motor 32 is short-circuited and thus actively braked. The windscreen wiper is situated in the parked position. Figure 12 shows an equivalent circuit diagram of the circuit in accordance with Figure 11. It can be seen that the switch which symbolizes the contact disc 10 establishes a connection between the motor 32 and the negative pole, with the result that the latter is short-circuited. The above description of the exemplary embodiments in accordance with the present invention serves only for illustrative purposes and not for the purpose of restricting the invention. In the context of the invention, various chanaes and modifications are possible without departing from the scope of the invention and its equivalents. WE CLAIM 1. A contact disc system of a windscreen wiper motor, comprising a rotatable contact disc (10) a plurality of contact elements (12,14, 16, 18), the contact disc (10) having a plurality of tracks (20, 22) and each contact element (12, 14, 16, 18) being assigned to a track (20, 22), characterized in that the contact disc (10) has two tracks (20, 22), and two selected contact elements (12, 14) of the plurality of contact elements (12, 14, 16, 18) are always at the same electrical potential and slide on the same track (20). 2. The contact disc system as claimed in claim 1, wherein the selected contact elements (12, 14) slide on a first track (20), which has an electrically conductive region (24) and an electrically insulating region (26), and at least one contact element (12, 14) of the selected contact elements (12, 14) is connected to the electrically conductive region (24) of the first track (20). 3. The contact disc system as claimed in claim 1 or 2, wherein the electrically insulating region (26) of the first track (20) is realized by an interruption of an electrically conductive track (20) and, the selected contact elements (12, 14) have a spacing which is greater than the interruption of the electrically conductive region (24). 4. The contact disc system as claimed in any one of the preceding claims, wherein a first further contact element (16) slides on the first track (20). 5. The contact disc system as claimed in any one of the preceding claims, wherein a second track (22) has an electrically insulating region (28) and an electrically conductive region (30) and a second further contact element (18) slides on the second track (22). 6. The contact disc system as claimed in any one of the preceding claims, wherein the interruption (26) of the first track (20), the electrically conductive region (30) of the second track (22), the first further contact element (16) and the second further contact element (18) are arranged with respect to one another in such a way that a state exists in which neither the first further contact element (16) nor the second further contact element (18) are connected to an electrically conductive region (24, 30) of the first track (20) and of the second track (22), respectively. 7. The contact disc system as claimed in any one of the preceding claims, wherein the angular range which is covered by the electrically conductive region (30) of the second track (22) is smaller than the angular range which is covered by the electrically insulating region (26) of the first track (20). 8. The contact disc system as claimed in any one of the preceding claims, wherein the contact elements (12, 14, 16, 18) are contact springs. 9. The contact disc system as claimed in any one of the preceding claims, wherein a switch (34) connected to the contact disc system is changed over and a rotation of the contact disc (10) is maintained vmtil the second further contact element (18) is connected to the electrically conductive region (30) of the second track (22). 10. The contact disc system as claimed in any one of the preceding claims, wherein before the connection of the second further contact element (18) to the electrically conductive region (30) of the second track (22), the connection of the first further contact element (16) to the electrically conductive region (24) of the first track (20) is interrupted.

Documents:

in-pct-2002-0345-che abstract.jpg

in-pct-2002-1011-che abstract-duplicate.pdf

in-pct-2002-1011-che abstract.pdf

in-pct-2002-1011-che claims-duplicate.pdf

in-pct-2002-1011-che claims.pdf

in-pct-2002-1011-che correspondence-others.pdf

in-pct-2002-1011-che correspondence-po.pdf

in-pct-2002-1011-che description (complete)-duplicate.pdf

in-pct-2002-1011-che description (complete).pdf

in-pct-2002-1011-che drawings-duplicate.pdf

in-pct-2002-1011-che drawings.pdf

in-pct-2002-1011-che form-1.pdf

in-pct-2002-1011-che form-18.pdf

in-pct-2002-1011-che form-26.pdf

in-pct-2002-1011-che form-3.pdf

in-pct-2002-1011-che form-5.pdf

in-pct-2002-1011-che pct.pdf

in-pct-2002-1011-che petition.pdf