EP1723015A1

EP1723015A1 - Wiper arm drive device

Info

Publication number: EP1723015A1
Application number: EP05714896A
Authority: EP
Inventors: Rudolf Gmuend; Guenther Friderichs; Harry Riedl
Original assignee: Bayerische Motoren Werke AG; Robert Bosch GmbH
Current assignee: Bayerische Motoren Werke AG; Robert Bosch GmbH
Priority date: 2004-03-02
Filing date: 2005-01-24
Publication date: 2006-11-22
Also published as: WO2005085025A1; DE102004010118A1

Abstract

The invention relates to a wiper arm drive device (1) for a windscreen wiper (14) on a motor vehicle, comprising a drive motor (58), a gearbox (60) with a gearwheel (68) and a position determining device (62), whereby the position determining device (62) comprises an electric sliding contact arrangement (26) with a contact (30) and an opposing contact (36). The contact (30) or opposing contact (36) is arranged on the gearwheel (68) such that the sliding contact arrangement (26) generates a first change in a first parking position (22) of the windscreen wiper (14) and a second change in a second parking position (24) to an electrical signal, whereby the signal change is analysed by an analytical device (28) affecting the control of the drive motor (58).

Description

Wiper arm drive device

The invention relates to a wiper arm drive device for a windshield wiper of a motor vehicle, with a drive motor, a transmission having a gear wheel and with a position determining device.

State of the art

Wiper arm drive devices of the generic type are known. They serve to drive at least one windshield wiper, which is guided in alternating directions over a windshield, for example a front or rear window, of a motor vehicle in order to remove impairments on the windshield, for example moisture, water drops or dirt, by means of the wiping movement. There are two operating modes when wiping the window, namely continuous wiping and interval wiping. The continuous wiping operation is characterized in that the next wiping cycle immediately follows the end of a wiping cycle - usually when a windshield wiper has reached a parking position. With interval wiping, on the other hand, the windshield wiper remains in a parking position for a certain time after the end of a wiping cycle before the next wiping cycle is initiated.

Windshield wiper systems in which the wiping field is operated by two windshield wipers, which are usually guided essentially simultaneously mainly have exactly one parking position in which the windshield wipers can be stopped / parked without impairing the driver's field of vision. In such a windshield wiper system, a windshield wiper sweeps over a range of approximately 90 ° to 110 °. In comparison, in a windshield wiper system with a wiper arm there is a significantly larger angle between the parking position and the reversing position, for example approximately 180 °.

DE 44 04 049 A1 shows a special use of the parking position and the reversed position of a windshield wiper system with a wiper arm for the interval wiping operation. It is proposed to use the reverse position as the second parking position in the interval wiping operation. The wiper arm does not carry out a complete wiping cycle, i.e. a wiping cycle with the same start and end position, but is stopped after half a wiping cycle, when the wiper arm has moved from one parking position to the other, and only sets after it has expired a predetermined time from this parking position from the wiping cycle. This is intended to improve the wiping function in the event of low water precipitation and to increase the service life of the wiping rubber. However, the published specification gives no indication of how such a windshield wiper system could be implemented, in particular not how the two parking positions are recognized. Position determination devices are known from the prior art which determine the parking and / or reversing positions of a wiper arm by means of limit switches, cams or a counting of the armature rotations of the drive motor. Such arrangements are always associated with significant design effort.

Advantages of the invention

The invention further develops the state of the art in that the position determination device has an electrical grinding contact. has a clock arrangement with a contact and a mating contact, the contact or mating contact being arranged on the gear wheel such that the sliding contact arrangement brings about a first change of an electrical signal in a first parking position of the windshield wiper and a second change in a second parking position, the signal change is evaluated by an evaluation device influencing the control of the drive motor. Such a position determination device of the wiper arm drive device is simple to implement, works reliably and has a small footprint, which is negligible in particular when comparing a conventional wiper arm drive device and a wiper arm drive device according to the invention.

An important component of the position determination device is the electrical sliding contact arrangement, which has a contact and a mating contact associated with this contact, the contact or mating contact being arranged on the gear wheel. If the drive motor is switched on, the wiper arm is moved via the intermediate gear. Since the gear wheel of the gear moves, the contact and counter contact make a relative movement to each other. The arrangement of the contact and mating contact of the sliding contact arrangement is selected such that the sliding contact arrangement causes a change in an electrical signal carried by the sliding contact arrangement at the positions of the gear wheel, which correspond to a first and a second parking position of the wiper. This signal change bears the information that a parking position has been reached - possibly also which parking position has been reached - and is evaluated by an evaluation device which influences the control or regulation of the drive motor. The motor is preferably stopped or electrically braked when a parking position is detected and, if an interval wiping mode has been selected, stopped for a certain time before another half wiping cycle is initiated. The signal change is brought about in that the contact and countercontact can be brought into electrical contact with one another and separated again, that is to say that the sliding contact arrangement is opened and closed.

The contact advantageously has at least a first and a second contact element and the counter contact has at least a first and a second counter contact element, the contact elements or counter contact elements arranged on the gear wheel being electrically connected to one another. Although it is fundamentally possible to implement the wiper arm drive device according to the invention with a contact element and a counter-contact element, namely if the gear wheel forms part of the signal circuit, the implementation of the invention can be further simplified if the contact and / or counter-contact are made in several parts. The side of the electrically interconnected elements (contact elements or counter-contact elements) represents an electrical bridge with which the other, electrically separated elements can be electrically connected. A connection of these elements or a disconnection of this connection always causes a change in the signal carried by the sliding contact arrangement. It should be pointed out that neither the contact elements with one another nor the counter-contact elements have to be identical to one another, but this standardization usually means a simplification in production. It is essential that the contact elements and counter-contact elements perform the function described.

An advantageous embodiment of the invention results when the first mating contact element is designed in the form of a segment of a ring or a ring with a first average radius around a center, the center lying on the axis of rotation of the gear wheel. This allows the required Clearly defined relative movement of the contact elements and counter-contact elements relative to one another can be realized in a particularly simple constructive manner.

The second mating contact element advantageously has at least one circular ring segment and is formed with a second mean radius around the center point.

In an advantageous development of the invention, the first mating contact element is designed in the form of a ring and the second mating contact element is designed in the form of a semi-ring. Since usually half a rotation of the gear wheel corresponds to the path of the windshield wiper from one parking position to the other, or an entire rotation of the gear wheel corresponds to a full wiping cycle, the mating contact can be carried out particularly easily in this way. This means that with one revolution of the gear wheel, ie a complete wiping cycle, two signal changes are produced which correspond to the two different parking positions, the signal changes being different for each of the two parking positions. This means that the evaluation device can not only determine that one of the two parking positions has been reached, but that, based on the type of signal change, a statement can also be made about which of the two parking positions was approached.

It is advantageous if the second counter-contact element has two contact lugs, which are diametrically opposed with respect to the center. The position of the contact lugs corresponds to the parking position of the wiper. Since two signal changes occur with each contact lug, namely when the contact lug reaches and when leaving, a total of four signal changes take place per revolution of the gear wheel. A first, always similar signal change takes place when one of the contact lugs is reached, and a second, always similar signal change occurs when one of the two contact lugs is left. When the wiper arm drive device is implemented, it can now be determined whether the evaluation device should react to the signal change when a contact flag is reached or to the signal change when leaving a contact flag. Since the evaluation device therefore only has to recognize and evaluate one type of signal change, the evaluation device can be implemented in a simplified manner.

The contact elements or mating contact elements which are electrically connected to one another are advantageously made in one piece. This allows a simpler and cheaper production of the sliding contact arrangement.

An advantageous further development provides that the contact elements are designed as sliding contacts and the counter-contact elements are designed as sliding surfaces.

It is advantageous if a first electrical potential is applied to one of the electrically separated contact elements or counter-contact elements and a second electrical potential is applied to the other. This makes it easy to provide the electrical signal which is passed through or interrupted by the sliding contact arrangement. The difference between the first and second potential is so great that the connection or separation of the two potentials caused by the sliding contact arrangement can be determined by the evaluation device as a signal change. The potentials can be provided by voltages that are present anyway (battery voltage, operating voltage, control voltages, etc.).

The first or the second electrical potential is advantageously a ground potential. Ground potentials are available in many places in a motor vehicle, so that the wiper arm drive device according to the invention can be implemented in a simplified manner. In an advantageous embodiment of the invention it is provided that the first and the second contact element are arranged with different radii to the axis of rotation of the gear wheel.

The counter-contact elements are advantageously arranged on an end face of the gear wheel and the contact elements are arranged in a fixed position on a gear housing of the wiper arm drive device. The areal end face of the gear wheel can thus be used advantageously for an arrangement of the mating contact elements, in particular in the embodiment as grinding surfaces.

The gear advantageously has a worm reduction gear and the gear wheel is designed as a worm gear. Since the windshield wiper has to be driven at a lower rotational angular speed, but at the same time with a higher torque than that provided by the drive motor, a worm reduction gear can easily bring about the necessary adjustment.

Finally, the invention relates to a windshield wiper system, comprising a wiper arm drive device with one or more of the aforementioned features.

drawings

The invention is explained in more detail below with exemplary embodiments with reference to the associated drawings. Show it

FIG. 1 shows a windshield wiper system with a windshield wiper,

FIG. 2a shows a schematic illustration of a first exemplary embodiment of a sliding contact arrangement and an evaluation device, FIG. 2b the reaching of a parking position in the first exemplary embodiment,

Figure 3 is a schematic representation of a second embodiment of a sliding contact arrangement and an evaluation device, and

FIG. 4 shows an exemplary embodiment of a wiper arm drive device.

Description of the embodiments

FIG. 1 shows a rear window 10 of a motor vehicle (not shown in more detail) and a single-arm windscreen wiper system 12 assigned to the rear window 10. Of the windscreen wiper system 12, only the windscreen wiper 14 is shown, which rotates at one end about an axis of rotation 16 and with its wiper blade 18 causes a wiping area 20 on the rear window 10. During the wiping process, the windshield wiper 14 moves from its first parking position 22 (shown with solid lines) to its second parking position 24 (shown with a dash-dotted line) and then back again into its first parking position 22. In the continuous wiping operation, the parking positions 22 and 24 only set this way - said reverse positions, that is, the wiper 14 carries out a continuous wiping movement and always changes its direction of movement in said positions. In the intermittent wiping operation, the windshield wiper 14 executes a half wiping cycle, ie moves from one parking position 22, 24 to the other parking position 22, 24 and remains there for a predetermined time before continuing the wiping cycle. Of course, it is possible to end the wiping movement in each parking position 22, 24 and to switch off the windshield wiper system 12. When the windshield wiper system 12 is actuated again, the windshield wiper 14 starts then from the parking position 22, 24 last reached. In order to brake and / or stop the movement of the windshield wiper 14 when one of the parking positions 22, 24 is reached in interval wiping operation, precise knowledge of the position of the windshield wiper 14 is required.

FIG. 2a shows a sliding contact arrangement 26 and an evaluation device 28. The sliding contact arrangement 26 has a contact 30 with a first contact element 32 and a second contact element 34, as well as a counter contact 36. In this exemplary embodiment, the counter contact 36 is embodied in one piece as a conductive contact disk, the dashed line indicating that the counter contact 36 is composed of an imaginary first counter contact element 38 and an imaginary second counter contact element 40. The first mating contact element 38 is in the form of a ring with a first average radius R1 around a center point M. The second mating contact element 40 is in the form of a ring with a second mean radius R2 around the center point M. The counter contact 36 rotates during operation of the windshield wiper system 12 in the plane of the drawing about the center point M.

A first potential 42 is present at the first contact element 32 of the contact 30, which is provided here by the ground potential GND. The second contact element 34 is connected to the evaluation device 28 and is set to a second potential 44 by the voltage source U contained in the evaluation device 28. It is not necessary for the evaluation device 28 to actually generate a voltage. Rather, it is sufficient if the evaluation device 28 taps or forwards a voltage that is already present in the motor vehicle.

The constellation shown in FIG. 2a shows that the first contact element 32 with the counter contact 36, or with - lo ¬

The first mating contact element 38 is in contact, while the second contact element 34 has no electrical connection to the mating contact 36. The situation shown occurs, for example, while the windshield wiper 14 moves from the first parking position 22 into the second parking position 24. Since the first contact element 32 is electrically separated from the second contact element 34, or the first potential 42 and the second potential 44, the evaluation device 28 determines that the second potential 44 corresponds to the voltage provided by the voltage source U. During the operation of the windshield wiper system 12, the mating contact 36 rotates around the center point M, a rotation with the clockwise direction being assumed here as an example.

When the second parking position 24 is reached, the mating contact 36 has reached the position shown in FIG. 2b. The first contact element 32 is still in electrical contact with the mating contact 36. In addition, the second contact element 34 now comes into contact with the mating contact 36, or with the second mating contact element 40. Due to the conductive property of the mating contact 36, an electrical connection is now established between the first contact element 32 and the second contact element 34, so that the second potential 44 is now connected directly to the first potential 42 and is thus now pulled to ground. The evaluation device 28 recognizes the falling edge of the potential drop and thus the reaching of the second parking position 24. In the intermittent wiping operation, the movement of the windshield wiper 14 is then stopped. If the windshield wiper 14 is then moved again from the second parking position 24 into the first parking position 22, the counter-contact 36 rotates — further clockwise — into a position offset by 180 ° with respect to FIG. 2b. In this position, the second contact element 34 loses electrical contact with the counter contact 36, so that the electrical connection between the first contact element 32 and the second contact element 34 is interrupted. This turns the second potential 44 from the first Potential 42 decoupled and adjusts itself again to the voltage provided by the voltage source U. The rising edge of the potential increase is recognized by the evaluation device 28 and corresponds to the reaching of the first parking position. In the interval wiping operation, the movement of the windshield wiper 14 is again suspended here for a predetermined time. A complete revolution of the mating contact 36 corresponds to a complete wiping cycle, for example from the first parking position 22 to the second parking position 24 and back to the first parking position 22. With this rotational movement, the evaluation device 28 detects two different signal changes, namely a falling edge and a rising edge, each of which corresponds to reaching the second parking position 24 or the first parking position 22. It should be noted that the designation and assignment of the parking positions can also be chosen differently.

FIG. 3 shows a further exemplary embodiment of a sliding contact arrangement 26 with an evaluation device 28. In this exemplary embodiment, a counter contact 36 is used which has a first circular counter contact element 38 and a second counter contact element 40, which consists of two contact lugs 46, 48, which relate to the center point M are diametrically opposite. In this embodiment of the mating contact 36, the connection between the first contact element 32 and the second contact element 34 is established twice and interrupted twice when the mating contact 36 is rotated completely. The design of the contact lugs 46, 48, in particular their edges 50 facing the direction of rotation or their edges 52 facing away from the direction of rotation, is selected such that the evaluation device 28 only reaches a parking position 22, 24 on the basis of falling edges (triggered by the edges 50) or only on the basis of rising edges (triggered by the edges 52). An exact detection of the parking positions 22, 24 is thereby still ensured, with the evaluation device 28 merely must recognize a type of flank and can therefore be simplified in terms of construction.

FIG. 4 shows a wiper arm drive device 1 with a first housing part 54, a second housing part 56, a drive motor 58, a gear 60, a position-determining device 62 and an output shaft 64. The gear 60 comprises a worm 66 which is driven by the drive motor 58 and into one Gear wheel 68 engages, which is designed here as a worm wheel 70. The gear wheel 68 rotates about an axis of rotation 86 and has an end face 88. A conversion gear 74 is operatively connected to a receptacle 72 arranged on the worm wheel 70 and drives the output shaft 64 with the aid of a partial toothed ring gear ratio 76. The windshield wiper 14, not shown here, is then connected to the output shaft 64. The position determination device 62 includes the mating contact 36, here designed as a sliding surface 78, and the first contact element 32 and the second contact element 34, which are designed here as sliding contacts 80, 82.

During the operation of the wiper arm drive device 1, the drive motor 58 is always operated in one direction. This means that the worm wheel 70 driven by the worm 66 also always rotates in one direction. The conversion gear 74, which engages with its pin 84 in the assembled state in the receptacle 72, converts the unidirectional rotational movement of the worm wheel 70 into an alternating movement of the output shaft 64. As already explained in detail with reference to FIGS. 2a and 2b, the drive motor 58 is stopped in the intermittent wiping operation when the position determination device 62 has identified a parking position 22, 24. The evaluation device 28 is not shown in FIG. 4 for the sake of clarity. Of course, the wiper arm drive device 1 also allows a continuous wiping operation in which the drive motor 58 is operated continuously, even if the position determining device 62 recognizes a parking position 22, 24.

The mating contact 36 is firmly connected to the gear wheel 68 on its end face 88 and thus always carries out the same rotation angle as the gear wheel 68. The first contact element 32 and the second contact element 34 are arranged in a stationary manner on the first housing part 54 or the second housing part 56, so that when the gear wheel 68 rotates, there is a relative movement between the mating contact 36 and the first and second contact elements 32, 34. With regard to the mode of operation, reference is made to the explanations for FIGS. 2a and 2b.

Claims

claims

1. Wiper arm drive device (1) for a windshield wiper (14) of a motor vehicle, with a drive motor (58), a transmission (60) having a gear wheel (68) and with a position determining device (62), characterized in that the position tion determining device (62) has an electrical sliding contact arrangement (26) with a contact (30) and a counter contact (36), the contact (30) or counter contact (36) being arranged on the gear wheel (68) such that the sliding contact arrangement (26) causes a first change in a first parking position (22) of the windshield wiper (14) and a second change in an electrical signal in a second parking position (24), the signal change being evaluated by an evaluation device (28) influencing the control of the drive motor (58) ,

2. Wiper arm drive device (1) according to claim 1, characterized in that the contact (30) has at least a first and a second contact element (32, 34) and the counter contact has at least a first and a second counter contact element (38, 40). wherein the contact elements (32, 34) or counter-contact elements (38, 40) arranged on the gear wheel (68) are electrically connected to one another.

3. Wiper arm drive device (1) according to claim 2, characterized in that the first counter-contact element (38) in the form of an annular segment or in an annular manner with a first central radius us (R1) is formed around a center point (M), the center point (M) being on the axis of rotation (86) of the gear wheel (68).

4. Wiper arm drive device (1) according to claim 3, characterized in that the second mating contact element (40) has at least one circular ring segment and is formed with a second mean radius (R2) around the center point (M).

5. Wiper arm drive device (1) according to one of claims 2 to 4, characterized in that the first mating contact element (38) is annular and the second mating contact element (40) is semi-circular.

6. Wiper arm drive device (1) according to one of claims 2 and 3, characterized in that the second counter-contact element (40) has two contact lugs (46, 48) which are diametrically opposite with respect to the center point (M).

7. Wiper arm drive device (1) according to one of claims 2 to 6, characterized in that the electrically connected contact elements (32, 34) or counter-contact elements (38, 40) are made in one piece.

8. Wiper arm drive device (1) according to one of claims 2 to 7, characterized in that the contact elements (32, 34) are designed as sliding contacts (80, 82) and the counter-contact elements (38, 40) as sliding surfaces (78).

9. Wiper arm drive device (1) according to one of claims 2 to 8, characterized in that on one of the electrically separate contact elements (32, 34) or counter-contact elements (38, 40) a first electrical potential (42) and a second electrical potential (44) is applied to the other.

10. Wiper arm drive device (1) according to claim 9, characterized in that the first or the second electrical potential (42,44) is a ground potential (GND).

11. Wiper arm drive device (1) according to one of claims 2 to 10, characterized in that the first and the second contact element (32, 34) are arranged with different radii to the axis of rotation (86) of the gear wheel (68).

12. Wiper arm drive device (1) according to one of claims 2 to 11, characterized in that the counter-contact elements (38, 40) on an end face (88) of the gear wheel (68) and the contact elements (32, 34) stationary on a gear housing (54, 56) of the wiper arm drive device (1) are arranged.

13. Wiper arm drive device (1) according to one of the preceding claims, characterized in that the gear (60) has a worm reduction gear (66,68) and that the gear wheel is designed as a worm wheel (70).

14. Windshield wiper system (12), characterized by a wiper arm drive device (1) according to one of the preceding claims.