Method for detecting torque in a transmission, measuring device and control program

1. A method for determining a torque in a transmission having a pair of gearwheels with intermeshing teeth that deform under load, comprising the steps of:

detecting with at least one vibration sensor at least one vibration signal associated with a tooth engagement frequency of the intermeshing teeth of the gearwheels;

determining a phase shift of the at least one vibration signal, said phase shift depending on the tooth engagement duration, wherein the at least one tooth engagement duration depends on a torque value in the transmission caused by deformation of the intermeshing teeth under the load; and

determining the torque value acting on the transmission from the phase shift or the at least one tooth engagement duration, or both.

2. The method of claim 1 , further comprising the steps of determining a torque-dependent difference between phase shifts of tooth engagement frequencies of at least two different tooth engagements, and determining the torque value acting on the transmission from the difference between the phase shifts.

3. The method of claim 1 , further comprising the steps of detecting a plurality of vibration signals or vibration signal components which are associated with a plurality of different tooth engagements, and determining an average torque value acting on the transmission by averaging the plurality of vibration signals or vibration signal components.

4. The method of claim 3 , further comprising the steps of monitoring differences between the average torque value and individual measured torque values, and generating an alarm signal when a deviation lies above a predetermined threshold value.

5. The method of claim 4 , wherein the alarm signal comprises an indication of an affected tooth engagement.

6. The method of claim 1 , further comprising the steps of

transforming the at least one vibration signal from a frequency domain into a time domain, and

determining from the vibration signal transformed into the time domain a tooth engagement duration between a time when a tooth of a first gearwheel first makes contact with a meshing tooth of a second gearwheel of the transmission and a time when the tooth of the first gearwheel last makes contact with the meshing tooth of the second gearwheel, or

a tooth engagement duration between a time when in absence of contact between other teeth of the first and second gearwheel, the tooth of the first gearwheel makes exclusive contact with the meshing tooth of the second gearwheel of the transmission and a time when the tooth of the first gearwheel last makes exclusive contact with the meshing tooth of the second gearwheel,

or both.

7. The method of claim 1 , further comprising the step of band-pass-filtering the at least one vibration signal in a predetermined frequency range about a basic tooth engagement frequency.

8. The method of claim 7 , wherein the basic tooth engagement frequency is determined by a revolution counter.

9. The method of claim 1 , wherein the at least one vibration sensor is constructed as an airborne sound vibration pickup or a structure borne sound vibration pickup.

10. The method of claim 1 , wherein the at least one vibration sensor constructed as sensor of a condition monitoring system employed for determining a vibration signature.

11. A measuring device for determining a torque acting on a transmission having a pair of gearwheels with intermeshing teeth that deform under load, said measuring device comprising:

at least one vibration sensor for measuring at least one vibration signal associated with a tooth engagement frequency of the intermeshing teeth of the gearwheels, said at least one vibration signal defining a phase shift which depends on at least one torque-dependent tooth engagement duration; and

a signal processing unit operatively connected to the at least one vibration sensor for determining the torque acting on the transmission from the phase shift of the at least one vibration signal or the at least one torque-dependent tooth engagement duration.

12. A control program for detecting torque in a transmission having a pair of gearwheels with intermeshing teeth that deform under load, said control program stored on a non-transitory computer-readable medium and having at least one code section which, when loaded into a memory of a data processing device and executed in the data processing device, causes the data processing device to:

detect with at least one vibration sensor at least one vibration signal associated with a tooth engagement frequency of the intermeshing teeth of the gearwheels;

determine a phase shift of the at least one vibration signal, said phase shift depending on at least one tooth engagement duration of the intermeshing teeth of the gearwheels, wherein the at least one tooth engagement duration depends on a torque in the transmission caused by deformation of the intermeshing teeth under the load; and

determine a torque value acting on the transmission from the phase shift or the at least one tooth engagement duration, or both.