Handheld work apparatus having a combustion engine
A handheld work apparatus has a combustion engine and an ignition device for controlling a spark plug. The ignition device includes an electronic control device having a short circuit button for switching off the combustion engine. A temperature sensor is for capturing an operating temperature. The short circuit button and the temperature sensor are connected to a common signal input of the control device via a common signal line. The temperature sensor is an ohmic resistance variable on the basis of the temperature. A measurement voltage dropped across the resistance of the temperature sensor is supplied, as an analog temperature signal, to a common analog signal input of the control device. The measurement voltage at the temperature sensor collapses in the button position of the short circuit button, as a result of which the analog temperature signal applied to the analog signal input of the control device is extinguished.
1. A handheld work apparatus comprising:
a motor housing;
a spark-ignition combustion engine arranged in said motor housing;
a spark plug;
an ignition device for controlling said spark plug;
said ignition device including an electronic control device;
a short circuit button with a button position for switching off said combustion engine;
a first temperature sensor for capturing an operating temperature;
said control device having a common signal input;
a common signal line;
said short circuit button and said first temperature sensor being connected to said common signal input of said control device via said common signal line;
said first temperature sensor including an ohmic resistance which is variable on the basis of temperature;
a measurement voltage (U T ) dropped across said ohmic resistance of said first temperature sensor being supplied, as an analog temperature signal (S), to a common analog signal input of said control device; and,
wherein said measurement voltage (U T ) at said first temperature sensor collapses in said button position of said short circuit button and said analog temperature signal (S) is extinguished.
2. The work apparatus of claim 1 , wherein:
said ohmic resistance of said first temperature sensor is a first ohmic resistance;
said short circuit button is in the form of a normally open contact and is in parallel with said first temperature sensor;
said first ohmic resistance of said first temperature sensor is greater than a second ohmic resistance of said short circuit button closed in said button position in a predefined temperature range.
3. The work apparatus of claim 1 , wherein said short circuit button is in the form of a normally closed contact and is open in said button position, and said short circuit button is in series with said first temperature sensor.
4. The work apparatus of claim 1 , wherein said control device includes a microprocessor.
5. The work apparatus of claim 1 , wherein said short circuit button is connected to said signal input of said control device via two signal lines.
6. The work apparatus of claim 1 further comprising:
an encapsulated housing;
said short circuit button and said first temperature sensor being arranged in said encapsulated housing.
7. The work apparatus of claim 1 , further comprising an encapsulated housing having a common connecting line for said short circuit button and said first temperature sensor.
8. The work apparatus of claim 1 , wherein said short circuit button is a microswitch.
9. The work apparatus of claim 1 further comprising:
a plurality of anti-vibration elements;
said combustion engine being held in said motor housing of the work apparatus with said anti-vibration elements; and,
said first temperature sensor being arranged on a vibration-decoupled side of said motor housing.
10. The work apparatus of claim 1 , wherein said first temperature sensor is configured to capture an ambient temperature of the work apparatus.