8661High-precision torque sensor

• Dual-range model
• Ratio 1:10
• High precision for both measurement ranges
• Scaled standard signal output for both measurement ranges
• No downtimes for sensor replacement
• Cost savings

Task

In order to improve the electromechanical energy conversion in geared motors in different load scenarios with a view to long operation lives, it is essential to measure mechanical, electrical and thermal characteristics in endurance testing.

Specific requirement

During the start-up phase under load, disproportionately high starting torques often arise that lie well above the steady-state load torque.

Solution

The dual-range model can be used to measure precisely and reliably the starting torque in the first measurement phase and the steady-state load torque in the second phase. The change to the second measurement range is made by applying a signal level to the switchover channel.

• High accuracy
• Rapid measuring value collection
• Configuration via PROFIBUS 

TASK

On a completely automated test bed motor vehicle seats should be checked for their encumbrance. The following features should be tested and recorded:

• Adjusting angle of the back
• Torque required for turning handle
• Total weight of the seat (with and without dummy)
• End position determination

In order to be able to make a well defined statement about the categorization of the motor vehicle seat, the measurement data must be recorded and networked and deposited together as test result on the PROFIBUS level.

SPECIFIC REQUIREMENT

All test data should be transferred at the same time for storage, in order to obtain relevant samples of information for comparative logging of this test. A tare function is a consideration for mounted sensors addressing the issue concerning initial load (dummy load).

SOLUTION

For the recording of all mechanical values following sensors are used:

• Adjusting angle of the back → angular displacement sensor model 8820
• Torque of the turning handle → torque sensor model 8661
• Total weight of the seat → 2 load cells model 8526
• End position determination → displacement sensor model 8719

All sensor signals are recorded by 4 individual Sensor Profibus Modules 9221. Concomitantly the modules display the sensors with voltage and evaluate their signals. The transferring of measurement data takes place in parallel via PROFIBUS. The tare activation concerning a possible initial load, which can be modelled as a dummy, takes place directly via simple PLC unit communication, over PROFIBUS.

• Torque measurement < 0.1 Nm
• Speed measurement up to 20000 1/min
• Includes built-in USB port
• High measurement cycle rates
• Visualization and data logging in one measurement step

Task

Das Reibmoment an gefetteten Kugellagern soll erfasst werden. The torque is applied using a variable-speed controlled asynchronous AC motor. Depending on the amount of grease in the ball bearing, the motor is run at different speed levels for various time intervals in order to obtain continuous measurements of the friction torque.

Specific Requirement

Protokollierung der Messdaten über die integrierte USB-Schnittstelle. 

Solution

Das Reibmoment wird im Dauerlauf kontinuierlich vom Drehmomentsensor Typ 8661 erfasst und via USB-Schnittstelle an die PC-Software DigiVision zur Visualisierung und Protokollierung übergeben. 

• Plug&Measure software system with auto-scaling function
• Quick to put in operation
• Mathematical formula editor
• Numerical or graphical display of results
• Free driver package can be used for interfacing with LabVIEW or for integrating custom software
• Dual-range sensor

TASK

Miniature electric motors need to be intensively tested after final assembly in serial production to assess their electromechanical properties. This testing involves measuring torque and speed to assess subsequent mechanical power values. The test setup is required to provide high levels of precision, straightforward measurement-signal processing and overload protection. 

SPECIFIC REQUIREMENT

• Rugged design
• Strong overload protection
• High reproducibility
• Low moment of inertia
• Measurement data available in digital form
• Two separately calibrated measurement ranges

SOLUTION

The low torques in this application mean that the measurement range must be chosen to achieve the necessary accuracy and overload protection. 

The dual-range model of the 8661 torque sensor is permanently mounted between two full couplings: between sensor and drive and between sensor and transmission arm. These couplings are designed to correct vertical and angular misalignments and differences in length.
The torque and speed measurement signals are output via the built-in USB port for further processing. The DigiVision software, which is included with the sensor, can be used not only to capture, visualize and archive the measurement data but also to calculate the mechanical power.

• Integral angle measurement
• Linearity error as low as 0.05 % F.S.
• DigiVision Plug & Measure PC software supplied as standard
• LabVIEW interface or alternative driver package for integrating in-house software available at no extra cost
• Dual-range sensor

Task

Actuation torques of motor starters need to be recorded during serial production. The aim is to log consistent product quality over a prolonged period. This requires storing raw data in a file that can be accessed later for analysis. Anything blocking the toggle switch can result in inadmissible spikes in the torque.

Specific Requirement

• Continuous storage of measured values
• High measurement accuracy with low linearity error
• A faulty end product can cause overload

Solution

Precision torque sensor model 8661 is selected because of the  need for high measurement accuracy and a PC interface. The DigiVision PC software stores the measurement signals in their raw, unprocessed form, so that they can be accessed later by analysis software. The user is provided with both the torque signal and the angle signal. This association is important in helping to identify any faults in the product under test. An adjustable safety coupling is used to prevent damage to the torque sensor 8661 in the event of an overload caused by obstruction of the toggle switch. This coupling not only provides protection but is also able to correct any misalignments.

• High dynamic performance
• Torque/speed/power calculation
• Redundant power measurement
• Rugged design
• High measurement accuracy

TASK

After assembly, the electric-bike drives need testing for correct operation. The speed lies in the range 1 to 254 1/_min. The speed and torque must be measured (setpoint and actual values), with a continuous plausibility check. The process data must be logged and archived.

SPECIFIC REQUIREMENT

• High measurement accuracy
• Compact design
• Reliable speed measurement even at low speeds
• Range of fixing options to allow easy fitting of torque sensor
• Transfer of measurement data to PC via USB plus LabVIEW analysis of data

SOLUTION

An air-cooled magnetic particle brake was used as the test load. The setup also includes a manual quick-release unit and a manual connection unit for making electrical contact with the object under test. The precision torque-monitoring function is integrated in the safety circuit and used for the power calculation. The 8661 torque sensor with integral speed sensor was selected. The LabVIEW software is used for machine programming and for combined analysis and on-screen visualization of measurement results in the form of tables or graphs. The industrial PC is used for creating test programs and selecting the object under test.

• Rugged design
• Torque/speed/power calculation
• High measurement accuracy
• High speed
• Instantaneous measurement of starting torque

TASK

The task is to test the motor performance of an industrial fan used for air purification and ventilation. Similar to testing an engine, this test setup is designed to measure the torque, speed and power.

SPECIFIC REQUIREMENT

• Stable performance in exposed mounting position
• High measurement accuracy
• Real-time acquisition of torque and speed
• PC-based analysis
• Zero-maintenance operation, ideal for inaccessible installation locations

SOLUTION

The 8661 torque sensor is permanently mounted between two couplings: between drive and rotor. These couplings are designed to correct vertical and angular misalignments and differences in length. The torque and speed measurement signals are available to the user for further processing. The optional USB interface can be used with the application-oriented DigiVision software for analysing the measurements. In addition to capturing, visualizing and archiving the measurement data, this software can also be used to calculate the mechanical power.

• High measurement accuracy
• Rugged design
• Zero-maintenance operation
• Optical signal transmission
• Bidirectional torque measurement

TASK

Waves produce movement of an elongated drive unit, secured by three cables to the seabed, which then transfers mechanical energy via a cable to a generator, which is mounted on a wind turbine tower and shielded from seawater. 
The latest development work is focussed on float trajectory and control strategy, with designs achieving up to 80 % utilization of the incoming wave energy for driving electric generators. 

SPECIFIC REQUIREMENT

• Extremely stable over time
• Excellent reproducibility
• Compact torque sensor
• Capable of operating under wide-ranging power conditions to accommodate potential fluctuations in the supply voltage

SOLUTION

The 8661 torque sensor is permanently mounted between two couplings. These couplings are designed to correct vertical and angular misalignments and differences in length. The torque and speed measurements are available as analog or TTL signals for further processing. In addition, the optional USB interface can be used for digital analysis of the measurement data.

• Extremely fine 0.09° angular resolution
• Axial load
• Bidirectional torque measurement
• Rugged design
• Sampling rate up to 1 kHz

TASK

The task is to measure the static and dynamic torques in a test setup for a fan. An 8661 torque sensor, and specifically the dual-range model, was selected for the task, because not only can it measure the torque of the rotor drive in widely-spaced ranges at two speed levels but it can also provide extremely accurate readings.

SPECIFIC REQUIREMENT

• Static and dynamic torque measurements
• High angular resolution
• Rugged design using durable and low-friction sensor bearings
• High sampling rate because of the different operating states
• Precise measurement of clockwise and anticlockwise torque

SOLUTION

The 8661 torque sensor measures the rotating and static torque at two positions. A torque/speed/power calculation is performed for the rotating torque. The optional USB interface can be used with the application-oriented DigiVision software for analysing the measurements. 
The reactive torque and rotational angle are measured for the static torque. The dual-range model of the 8661 torque sensor is available with a choice of range factors (1:4, 1:5 and 1:10) or a custom factor. Dual-range sensors allow measurements in an additional measurement range which is narrower but has high measurement accuracy.

• Measuring range 10 N*m with a linearity error of 0.05 % F.S.
• Integral angular position sensor with 2000 increments (maximum resolution 0.045°)
• Zero-maintenance contactless construction
• Analog output or USB version available
• Optionally available as a dual-range sensor

Task

Steering rods, as a safety-related component, must undergo a defined test procedure both in pre-production testing and during the production process. After compression of the bearing, it is tested for low breakaway and friction torques. Torque sensor 8661 with 10 N*m measuring range is used featuring a high-resolution angular position output, which is evaluated by a DIGIFORCE^® 9307. This process step can be used to prevent admissible component tolerances being exceeded.

• High dynamic performance
• High sensitivity for bidirectional torque measurements
• Standard output signal
• Torque, speed and power measurements
• Visual status indicator for distance monitoring

TASK

The dentist has the job of screw-fitting crowns to titanium dental implants. The torque needs to be monitored during implant screw-fitting. The torque typically lies in a range of 15 to 50 Ncm with a speed of 1500 to 2500 1/min.

SPECIFIC REQUIREMENT

• High reproducibility
• High speed
• Rugged design
• Ultra-low torques
• Extremely low-friction sensor bearing

SOLUTION

The 8661 torque sensor was selected for the torque measurement. The test setup measures an efficiency factor by comparing the drive and drag, i.e. the torque and speed, to give a quality rating.

Precision torque sensor model 8661

• Non-contact transmission
• Torque measurement < 0.05 Nm
• Angle resolution 0.0885 °

DIGIFORCE^® 9307

• Comprehensive process monitoring
• High sampling rate
• Measurement accuracy of up to 0.05 %

Task

The haptic behavior of rotary switches should be measured based on torque/rotation angle. The exact determination of the torque to be applied is an important control variable for a rotary switch in terms of haptic behavior (adjustment force to be applied > proprioceptive perception > tactile perception).  

Specific Requirement

Very low nominal torque due to low operating forces. Fine angle resolution to map the fine detent points of the rotary switch. 

Solution

The Type 8661 torque sensor measures even the smallest torques over a defined angle range in forward and reverse rotation with high precision and reproducibility. Using the Type 8661 torque sensor also reduces the design complexity, as no additional angle sensor is required.
The haptic behavior of the rotary switches is evaluated with the DIGIFORCE^® 9307 based on the torque/rotation angle curve.