Headspeed Governor
Was macht die interne Drehzahlregelung?
Die interne Drehzahlregelung ("Governor") des AR7210BX Empfängers steuert das Gas so, dass eine vorgegeben Rotordrehzahl im Flug konstant gehalten wird. Wenn z.B. das Pitch erhöht wird und dadurch die Last auf den Rotor steigt, wird das System mehr Gas geben, um die Motordrehzahl zu halten. Wenn Du andererseits mit dem Heli einen Abschwung fliegst und der Rotor entlastet wird, wird der Motor auftouren, das Gas muss weggenommen werden. Man könnte diese Art von Motorkontrolle auch über die Gaskurven in der Fernsteuerung machen, aber das ist im Ergebnis meist wesentlich ungenauer und aufwändiger. Viel einfacher ist es, dem System mitzuteilen, welche Rotordrehzahl man aktuell fliegen will, und das System kümmert sich dann um den Rest. Es hält die Drehzahl konstant über den gesamten Flug, sogar wenn der Antriebsakku leerer wird oder der Verbrennungsmotor abmagert. Man kann die Governor Funktion mit allen Elektrohelis verwenden, bei denen der Motorcontroller keine eigene, eingebaute "Governor Funktion" (Drehzahlregelung) hat bzw. über einen "Helimodus" verfügt oder wenn diese Funktion nicht zufriedenstellend funktioniert. Wenn Du einen Heli mit Verbrennungsmotor fliegst, brauchst Du keinen zusätzlichen Drehzahlregler mehr kaufen, mit dem AR7210BX Empfänger hast Du dieses Gerät schon mit an Board.
Hardware installation
Thus the Headspeed Governor of AR7210BX can be used, the system must be able to detect the motor speed. This is done with the help of a speed sensor that is plugged to the port AX2/RPM on the AR7210BX (the AUX2 output becomes an input when enabling the Governor!). For models with nitro/gas engines usually sensors are used that determine the speed signal magnetically or optically. These sensors are mounted next to the crankshaft or clutch bell and register the number of engine revolutions here. For electric motors the motor speed can be determined electronically. For this purpose a phase sensor (e.g. BXA76013) is connected to one or two of the motor phases. Some electric speed controllers also offer a direct signal output for the rpm signal, so that no additional sensor is required.
To see how the sensor is mounted in detail please refer to the instruction manual from the sensor or from the helicopter. The speed sensor plugged to the port AX2/RPM on the AR7210BX which also powers the sensor with the supply voltage, if necessary. Note that the height of the supply voltage corresponds to your receiver power supply voltage!
Here are some installation and connection examples. As described virtually all kinds of rpm sensors may be used. Unfortunately it is impossible to try and enumerate all types. If in doubt about whether a particular sensor can be used in conjunction with AR7210BX ask your dealer to find out.
Electric drive system with external phase sensor
Connect the motor wires of the phase sensor with any two phases of the electric motor. It is recommended to solder those wires to the plugs of the speed controller. So for maintenance purposes it is easier to remove the motor from the model later. In some cases the use of only one phase wire is sufficient. Usually this is the case when the speed controller powers the system with a BEC thus there is no galvanic isolation between motor and receiver circuit. However, we recommend using both wires in any case! This ensures that the sensor provides an interference-free signal as possible.
The electronic speed controller is plugged into the throttle output [THRO]. The phase sensor is plugged into AX2/RPM input.
Electric drive system with rpm signal output from the speed controller
When a speed controller is used that provides a rpm signal output you can directly plug the sensor wire from the ESC into the AX2/RPM input on the AR7210BX. In case the speed signal wire also has power lines watch our for correct polarity. The signal wire must be on top, the minus wire is connected at the bottom of the AR7210BX pin board. In case your speed controller doesn't come with power lines and only has one wire instead, make sure this wire is connected at the top of the device. The speed controller‘s control signal input is plugged into the throttle output [THRO] as usual.
Combustion drive system (nitro/gas)
Particularly when using sensors for combustion engines check for correct polarity of the sensor power supply. Here commonly sensors are used that are designed for governor systems from other manufacturers and therefore have a special pin assignment. In this case the colors of the connecting cables may not follow the norm (The wire colors of the ALIGN governor sensor HE50H22 are swapped for example. Here red denotes the negative and black the positive pole!). So make sure the signal wire is connected on top, plus is in the middle and the minus wire is connected at the bottom of the AR7210BX pin board.