WO1994001308A1

WO1994001308A1 - Circuitry for windshield wiper and washer of motor vehicles

Info

Publication number: WO1994001308A1
Application number: PCT/EP1993/001706
Authority: WO
Inventors: Norbert Normann; Gunter Lothar Schulze; Günter Uhl
Original assignee: Doduco Gmbh & Co. Dr. Eugen Dürrwächter
Priority date: 1992-07-04
Filing date: 1993-07-02
Publication date: 1994-01-20
Also published as: DE4221972C2; DE4221972A1

Abstract

A windshield wiper and washer for the front and rear windows, as well as other visibility related equipment to be supplied with load current (rear window heating, headlight washer and wiper, possibly also the lights) are controlled by a single controller (1) which is linked on the one hand by control lines (20a, 21a, 22a, 23a, 24a) to the corresponding control switches (20-24) and on the other hand is linked only by single-wire control lines (4, 6) to switching modules (5, 7) which incorporate the load switches, each module comprising several switching states and being assembled with one of the items of equipment (13, 15, 16, 18, 19) to form a subassembly.

Description

Circuit arrangement for a windshield wiper and washer system in motor vehicles

The invention relates to a circuit arrangement with the features specified in the preamble of claim 1. Such a circuit arrangement is known from DE-OS 39 22 230.

An electrical windshield wiper and washer system in motor vehicles usually includes a wiper motor for pivoting the wiper arms; a limit switch assigned to the wiper motor, sometimes also referred to as a parking switch, which is located in the circuit of the wiper motor and is controlled by the latter or by a linkage driven by the wiper motor in such a way that it opens in one end position of the windshield wipers and in any other position Wiper is closed, which ensures that the windshield wiper continues to run into that one end position after being switched off; at least one washing pump, with which water or a special washing liquid can be sprayed onto the pane to be cleaned; possibly a control circuit for interval operation of the wiper (hereinafter referred to as interval switching); and a multiple control switch for actuating the above-mentioned components, which is usually attached to the longitudinal column or in the immediate vicinity of the steering wheel on the dashboard.

In the usual type of electrical installation of the windshield wipers and washers in motor vehicles, the wiper motor is combined with the limit switch to form one structural unit; Otherwise, the components mentioned are connected to one another by numerous electrical lines in order to be able to carry out the different functions for the wiping operation, for the washing operation and for the interval wiping operation. Typically, six lines lead to the multiple switch, six lines to the interval switch, five lines to the unit formed from the wiper motor and the limit switch, and two lines to the wash pump. For this reason, numerous lines have to be laid, with the exception of the control line between the multiple switch and the interval switch, all lines carry the load current of the wiper motor or the washing pump and must accordingly have a sufficiently large line cross section. In view of the fact that the number of electrical lines in motor vehicles in the has risen sharply in recent years (a modern middle-class car contains an order of magnitude of 1000 m of cable), automobile manufacturers have now serious problems in accommodating the extensive cable harnesses in the vehicle.

DE-OS 39 22 230 has therefore already proposed that the load current for the wiper motor and for the wash pump no longer be conducted via the multiple operating switch, but rather to provide separate load switches which are combined in a switching module which is connected to the Wiper motor combined into a common assembly and is controlled by the multiple control switch, so that only weak control currents have to be transmitted between the latter and the switching module via correspondingly thin lines. This reduces the wiring effort.

It is known from DE-OS 29 44 224 ^'known switch to go out and the multiple Bedien¬ with only a single control line to be transmitted via this control line thereby lacking different tax charges, that a multi-stage voltage divider is provided, whose stages by multiple -Operating switches are selected so that, depending on the position of the multiple operating switch, a voltage between 0 V and the full on-board mains voltage of the motor vehicle is transmitted to a logic circuit which can recognize the different voltage levels and separate control circuits for the different functions ( Intermittent operation, wiper speed speed, blocking protection). As a result, the wiring between the multiple control switches and the logic circuit connected to them is simplified, but not between the logic circuit and the terminals, and the assignment of the voltage divider to the multiple control switch is disadvantageous.

The object of the present invention is to improve a circuit arrangement of the type mentioned at the outset in such a way that further simplification of the wiring in the motor vehicle can be achieved in the most economical manner possible.

This object is achieved by a circuit arrangement with the features specified in claim 1. Advantageous further developments of the invention are the subject of the dependent claims.

According to the invention, an interval switch and the various load switches for the windshield wiper and washer system are not combined in a common switching module and combined with the wiper motor to form an assembly, rather a uniform control device is introduced, which is accommodated separately from the wiper motor. This control device is connected on the one hand only via control lines to the operating switch and on the other hand only via a single-wire line to a switching module which Load switch for the wiper motor and the washing pump contains and is preferably combined with the wiper motor to form a module. This structure is outstandingly suitable for incorporating further end devices into a central control system, in particular further end devices for producing good visibility in the vehicle, namely the rear window wiping and washing system, the rear window heating and a headlight wiping and washing system as well as the lamps of the vehicle's lighting system. All of these terminal devices can be controlled via one and the same control device, so that only control lines, but no lines carrying load current, have to originate from the operating switches assigned to them.

The different switch positions in the switch modules are assumed in that the switch modules are supplied with correspondingly coded signals from the control unit via the single-wire lines, no complex digital data bus being required for this, rather a simple analog coding is sufficient because the number of data which is to be transmitted (in contrast to a digital motor control) is only slight and does not have to be transmitted particularly quickly and in a particularly dense succession of times. It is therefore sufficient and preferred that the control unit contains a driver which generates graduated analog DC voltage signals and applies them to the single-wire lines and that the respective switching module to which the respective leads single-wire line, has a detection circuit for such voltage signals. An example of this is described in DE-OS 29 44 224. By means of such an analog coding, as described in DE-OS 29 44 224, several control signals can also be transmitted from the operating switches via a common line to the control device.

It is preferably also provided that the control unit receives feedback about the switching states assumed in the switching modules. For this purpose, a feedback switch is preferably provided in the switching modules, which has the effect that a predetermined direct current signal is fed into the single-wire line in response to a changed direct voltage signal and that the control unit contains a current measuring element and an evaluation circuit assigned to it. The direct current signal can be generated by changing the ohmic load on the single-wire line as a function of the switching state, as a result of which the current in the single-wire line also changes in conjunction with the control voltage. However, it is also possible to have the single-wire line impressed by the feedback switch as a function of the switching state of the switching module, a current from a separate direct current source (battery).

Not only the mentioned control lines can be connected to the control device, but also the outputs of sensors with which the control can be influenced, e.g. a rain sensor that controls the switching on and off of the wiper motor and / or the pause time of the interval switching, or a speed sensor that controls the pause time of the interval switching and / or the wiping speed as a function of the vehicle speed.

The more terminal devices are controlled via the uniform control device, the more the wiring of the vehicle is simplified and the greater the advantage of the invention.

An embodiment of the invention is shown schematically in the accompanying drawing.

FIG. 1 shows a block diagram of a wiper-wash system according to the invention,

Figure 2 shows various control voltage signals, and

Figure 3 shows a feedback signal. The circuit arrangement shown in Figure 1 comprises a control device 1 with a connection 2 for connection to the vehicle battery and with a ground connection 3. A first output of the control device 1 is via a single-wire line 4 with a switching module 5 for a windshield wiper and washer and a second output is connected via a further single-wire line 6 to a switching module 7 for a rear window wiper and washer device. Another output of the control unit 1 is connected via a single-wire line 8 to a further switching module, not shown anymore, for example for a headlight wiping and washing system. The switching module 5 has a connection 9 for the vehicle battery and a ground connection 10. The switching module 7 has a connection 11 for the vehicle battery and a ground connection 12. Outputs of the switching module 5 are provided with a wiper motor 13 and a parking switch 14 coupled to it connected to a washing pump 15. Outputs of the switching module 7 are connected to a wiper motor 16 with a parking switch 17 coupled to it, to a washing pump 18 and to a heating device 19, the switching modules 5 and 7 and the wiper motors connected to them as terminals are connected via the power connections 9 and 11 13 and 16, washing pumps 15 and 18 and the rear window heating device 19 are supplied with current. The various functions for cleaning the front window and rear window are selected by an operating switch 20 with a plurality of switch positions. This switch 20 is connected to an input of control device 1 via one or more control lines 20a. A switch 23 for the rear window heating device is connected to a further input of the control device 1 via a control line 23a, control signals run in both directions via the control line 23a, towards the control device 1 for switching the rear window heating on and off, and towards the switch 23, to switch on a control lamp there when the heating is switched on.

With further inputs of the control device, a sensor 21 for the driving speed is connected via a control line 21a, a rain sensor 22 via a line 22a and a parking light sensor 24 via a control line 24a.

There are five switching functions for both the front and rear windows,

for the windscreen:

- everything OFF

- Wiper motor ON, first speed level

- Wiper motor ON, second speed level

- Wiper motor ON, first speed level, and wash pump ON

- Wiper motor ON, second speed level, and wash pump ON Rear window:

- everything OFF

- Wiper motor ON - Wiper motor and wash pump ON

- Rear window heater ON

- Wiper motor and rear window heater ON.

The communication between the control unit and the switching modules 5 and 7 for setting one of these switching states in the respective switching module takes place via the single-wire lines 4 and 6 with the aid of analog coded voltage signals as shown in FIG. 2: The first switching state corresponds to the DC voltage 0, which second switching state the DC voltage 25%, the third switching state 50%, the fourth switching state 75% and the fifth switching state 100% of the supply voltage (battery voltage) of the vehicle. These voltage levels are made available by a driver circuit provided in control unit 1. The switching modules 5 and 7 contain a detection and evaluation circuit which is able to recognize the respective voltage level and to switch the load switches for setting the desired switching state. In order to be able to report the respective switching status to the control unit 1, the switching modules 5 and 7 contain a feedback circuit which changes the ohmic load on the single-wire line 4 and 6 depending on the switching status. With that changes the current strength in the single-wire lines 4 and 6 (see FIG. 3), which can be measured and evaluated by a current measuring device provided in the control unit 1.

The communication between the switch 20 and the control device 1 can either take place via a plurality of parallel lines 20a, via which a signal is transmitted in each case, or via a line 20a via which a number of analog-coded DC voltage signals are transmitted, similarly to the single-wire lines 4 and 6.

The control device 1 also contains a known, e.g. the interval circuit described in EP-B-0 283 005, which allows the pause time between two wiping processes and possibly the wiping speed to be controlled, this control being able to take place with the aid of sensors 21 and 22 depending on the driving speed and the precipitation. The interval switching means that a headlamp wiper and washer system can also be switched on when the parking light sensor 24 signals that the vehicle is being driven with light.

A serial interface 25 is also provided on control unit 1 for connection to a general data bus in the vehicle. The invention has a number of advantages; in that only the most essential components for switching load currents for various end devices are combined in switching modules and combined with one end device to form an assembly, all other control tasks, however, can be carried out by a uniform control device for all switching modules with which the control device is only connected via single-wire lines, this results in a fairly simple installation with only a few lines. Communication can take place via analog signals and only requires simple, conventional evaluation electronics, but no microprocessor. Because of the use of analog coded signals, there are no EMC problems due to the emission of interference signals; rather, interference suppression is easily possible with the methods known in automotive engineering. By dispensing with unnecessary digitization, the control can be implemented cost-effectively.

The load currents can be switched both by electromechanical relays and by electronic switches (power semiconductors).

Claims

Claims:

1. Circuit arrangement for a wiper and

-Washing system in motor vehicles with the following components:

- a wiper motor (13, 16)

- a limit switch (14, 17) assigned to the wiper motor,

- at least one wash pump (15, 18),

- If necessary, a control circuit for an intermittent operation of the wiper (hereinafter referred to as an intermittent circuit), 0 and an operating switch (20) for actuating these components, load switches connecting the terminals (13, 15, 16, 18, 19) to a power source and from the operating switch (20) only go out control lines (20a),

L5 characterized by

that a uniform control device (1) is arranged between the load switches and operating switches (20, 23), which is connected to load switches for at least one further terminal device (16, 18, 19) and all functions of the terminal devices (13, 15, 16, 18, 19) controls that between them and the control unit (1) only single-wire lines (4, 6) and between the control unit (1) and the operating switches 5 (20, 23) only control lines (20a, 23a) run. 2. Circuit arrangement according to claim 1, characterized gekenn¬ characterized in that the control unit (1) contains a driver circuit, which graduated analog DC signals (Fig.

2) generated and connected to the single-wire lines (4, 6), and that several load switches each part of one

Switch module (, 5, 7), which has a detection circuit for such voltage signals.

3. Circuit arrangement according to claim 2, characterized in that the switching module (5, 7) contains a feedback switch, which causes the single-wire line (4, 6) in response to a changed direct voltage signal (FIG 2) a predetermined direct current signal (FIG. 3) is fed in, and that the control unit (1) contains a current measuring element and an evaluation circuit assigned to it.

4. Circuit arrangement according to claim 3, characterized in that the feedback switch changes the ohmic load of the single-wire line (4, 6).

5. Circuit arrangement according to claim 3, characterized in that the feedback switch connects the single-wire line (4, 6) to a separate direct current source.

6. Circuit arrangement according to one of the preceding claims, characterized in that as further terminals a wiper motor (16), a washing pump (18) and a heater (19) for the rear window are connected.

7. Circuit arrangement according to one of the preceding claims, characterized in that a wiper motor and a washing pump are used as further end devices

Headlight wipers and washers are connected.

8. Circuit arrangement according to one of the preceding claims, characterized in that lamps are connected as further terminal devices.

9. Circuit arrangement according to one of the preceding claims, characterized in that inputs of the

Control device (1) are connected to the outputs of sensors (21, 22, 24).