Input device for a motor vehicle with voltage-based error detection

Patent metadata

Field	Value
Publication number	US-12354823-B2
Application number	US-202118031489-A
Country	US
Kind code	B2
Filing date	Oct 6, 2021
Priority date	Oct 13, 2020
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

The invention relates to an input device ( 1 ) for safety-relevant functions of a motor vehicle, having a switch contact ( 3 ) with a first connection ( 4 ) and a mating contact ( 5 ) with a second connection ( 6 ). A first resistor ( 9 ) is connected between a voltage supply connection ( 8 ) and one connection ( 4, 6 ) of the switch element ( 2 ) and a second voltage supply connection ( 7 ) is connected to the other connection ( 4, 6 ) of the switch element ( 2 ). A measuring node ( 10 ), via which an actuation-dependent voltage can be captured, is provided between the first resistor ( 9 ) and the associated connection ( 4, 6 ). The problem addressed by the invention is that of developing input devices of the type in question such that they can be used for safety-relevant applications in the motor vehicle. This problem is solved by the switch contact ( 3 ) having a third connection ( 12 ) at which a second resistor ( 13 ), which is connected to the second connection ( 6 ) of the switch element ( 2 ), is provided.

First claim

The invention claimed is:

1. An input device for safety-relevant functions of a motor vehicle, comprising:
a switch element, which has a switch contact with a first connection and a mating contact with a second connection, wherein the switch contact is configured to make contact with the mating contact when the input device is actuated;
a first resistor, with a first and second voltage supply connection via which an operating voltage for the input device is provided, wherein the first voltage supply connection is connected to one of the connections of the switch element and the second voltage supply connection is connected via the first resistor to the other connection of the switch element;
a measuring node provided between the first resistor and the associated connection of the switch element and which is connected to a measuring connection, so that an actuation-dependent voltage, which is dependent on the actuation of the input device, is detected via the measuring connection,
wherein the switch element has a third connection which is connected to the switch contact, wherein a second resistor is provided which is connected to the second and third connections of the switch element so that, in the event of a fault of the switch contact, or a break of the switch contact, an error voltage is detected at the measuring node via the measuring connection and is distinguished from the actuation-dependent voltage; and
an evaluation circuit configured to detect the voltage at the measuring node via the measuring connection and thereby identify an actuation of the input device and/or a fault of the switch contact,
wherein the switch contact is rounded or dome-shaped and the first and third connections are provided in opposite regions of the rounded or dome-shaped switch contact.

2. The input device as claimed in claim 1 , wherein a third resistor is provided between the first voltage supply connection and the associated connection of the switch element so that the particular connection of the switch element is connected to the first voltage supply connection via the third resistor.

3. The input device as claimed in claim 1 , wherein the second voltage supply connection is connected to a positive operating voltage and the first voltage supply connection is connected to a reference potential of the input device.

4. The input device as claimed in claim 1 , wherein in the unactuated state of the input device an actuation-dependent voltage is detected at the measuring node, which voltage results from the voltage divider ratio between the first resistor and the second resistor and a third resistor.

5. The input device as claimed in claim 1 , wherein in the actuated state of the input device an actuation-dependent voltage which corresponds to the voltage or potential of the first voltage supply connection or results from the voltage divider ratio between the first resistor and a third resistor is detected at the measuring node.

6. The input device as claimed in claim 1 , wherein in the event of the fault of the switch contact or the break of the switch contact, the error voltage which corresponds to the voltage or potential of the second voltage supply connection is detected at the measuring node.

7. The input device as claimed in claim 1 , wherein the evaluation unit comprises an analog-to-digital converter so that the detected voltage can be converted into a digital value and digitally processed.

8. The input device as claimed in claim 1 , wherein, when the input device is actuated, the contact between the switch contact and the mating contact is galvanic or electrically conductive.

9. The input device as claimed in claim 1 , wherein, when the input device is actuated, the contact between the switch contact and the mating contact is resistive or capacitive.

10. The input device as claimed in claim 1 , wherein the switch element and the resistors are arranged on a printed circuit board and at least the first and third connections are solder points on the printed circuit board.

11. The input device as claimed in claim 10 , wherein the rounded or dome-shaped switch contact is soldered to the solder points for the first and third connections and the mating contact is provided between these two solder points on the printed circuit board.

12. The input device as claimed in claim 11 , wherein further support points for the rounded or dome-shaped switch contact are provided on the printed circuit board and are solder points.

Assignees

• Valeo Schalter & Sensoren Gmbh

Inventors

• Staude Sascha
• Leucht Florian
• Dietz Benjamin
• Mack Raphael

Classifications

• G01R31/3277

  of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches · CPC title

• H01H2239/012

  Decoding impedances · CPC title

• H01H9/167 Primary

  Circuits for remote indication · CPC title

• H01H9/16 Primary

  Indicators for switching condition, e.g. "on" or "off" · CPC title