Switching Device For Signaling A Binary Information Item

#1. Technical Field

#The invention relates to a switching device for the reliable, wire-bound signaling of a binary information item, containing a signal voltage terminal and a movable switch element connected thereto. In addition, the invention relates to an electronic engine controller for a motor vehicle, which is configured for the remote inputting of a binary information item.

#2. Background of the Invention

#FIG. 1 is a schematic view of the coupling of a switching device according to the invention.

#The switching device for the reliable, wire-bound signaling of a binary “on/off” information item contains a signal voltage terminal which can be connected to a source for a predetermined signal voltage as well as a movable switch element which is electrically connected to the signal voltage terminal. The switching device has three signal outputs, each one of which can be electrically connected to the signal voltage terminal via the switch element depending on the position of the switch element.

#Accordingly, the switching device makes it possible for the signal voltage that is fed to one signal voltage terminal to be optionally applied to precisely one of three signal outputs. This permits an unambiguous interpretation of the switch position at any time, the presence of the signal voltage at a first or second signal output representing the two logic values (“true/false”) of the binary information item and the presence of the signal voltage at the third signal input being also able to indicate a neutral position of the switch element, in which position no definite value of the binary information is predefined. This neutral position which can be selected and evaluated explicitly makes it possible to distinguish the intentional absence of a selection from an absence which is unintentional or due to a fault and which is present, for example, if the switch element does not have contact with any of the signal outputs and/or there is an interruption in the lines. A further advantage of the switching device is that incorrect behavior cannot occur as a result of a short circuit. If, for example, a further signal output is connected to the signal voltage as a result of a short circuit, there would no longer be only precisely one of the three signal outputs at the level of the signal voltage, as a result of which it would be possible to detect the fault. Furthermore, the switching device is protected from a fault due to a line interruption as such a line interruption would lead to an absence of the signal voltage at all three signal outputs, which would in turn represent a state which can be detected as being faulty.

#According to one embodiment of the switching device, the switch element is mounted in a pivoting fashion on an axis and has a slider that slides along contacts which are connected to the signal outputs. In this embodiment of the switching device, the slider can optionally be connected to, in each case, one of the contacts by turning or pivoting the switch element, and as a result the signal voltage that is present at the switch element can be applied to the respective signal output. In a comparatively simple structural configuration, such a switching device ensures that only precisely one of the signal outputs can be connected to a signal voltage at any time.