Transmission Test Bench
The test bench serves to determine and test the control characteristic of automatic transmissions with hydraulic and electronic control.
The tests are carried out on steplessly variable automatic transmissions as well as on automatic multi-step transmissions for front-wheel drive and rear-wheel drive and on special transmissions.
Static and dynamic test operation
In the static modes of operation, the test bench can be operated with torque regulation and speed regulation at both the input and output.
In the “road simulation” mode, motor torques are fed to the drive system by the host computer. The parameters for the output system (rolling resistance, air resistance, acceleration resistance, climbing resistance, additional static resistance) are processed by the road-simulation computer.
The test bench supplies the test piece with road and environmental data in the form of speed and torque values. Thus reproducible tests with simulated up- and downhill drive, kick-down acceleration, shift cycles at different transmission temperatures etc. can be carried out on the test bench, avoiding the installation of the test piece on a passenger car for the otherwise necessary road test.
To protect the test piece against damage, the test bench is additionally equipped with a starting and a stopping routine.
Task:
Test stand serves to discover and test control characteristic of automatic transmissions with hydraulic and electronic control.
To achieve this test gears are sped up in ambient temperature -40 to +50 C under part-load and run through dynamically defined ranges of total control resp. shift field provided in test programs, to analyse function of transmission control.
Test is carried out with steplessly variable automatic transmissions as well as with automatic multi-step transmissions for front and rear drive and with special-type transmissions.
Following operations of test stand are required:
- manual operation
- static automatic operation
- dynamic automatic operation
- road simulation
Solution:
Drive unit
To achieve high speed/torque dynamics with low mass inertia, drive is equipped with secondary hydromotors.
Hydromotor speed is geared up to required test stand speed by high-performance, play-free chain transmission.
Power take-off unit
Construction is roughly the same as with drive unit, maximal take-off torque is however 360 Nm. To balance offset of driven shafts for different transmissions power take-off unit is mounted on stable lift platform with cross slide. For quick cut-out of test stand in case of EM-OUT or test piece fault safety denture clutch is integrated in drive chain. Drive moment is measured with torque-measuring shaft, type T32 (make HBM). To achieve maximal rigidity with low mass inertia of drive, connection between drive unit and test piece is made with carbon-fibre reinforced plastic pipe. To test front-wheel driven test pieces side shafts are guided back over intermediate transmission to common take-off shaft and from there to take-off chain.
Road simulation
With “road simulation” programme motor torque’s are fed to drive system by master computer. Drive system parameters are processed by road-simulation computer ECB Z80. Parameters for road simulation:
- rolling resistance
- air resistance
- speed-up resistance
- slope resistance
- static additional resistance
Speed moment and torque acquired from control board and road and ambient data acquired from master computer with cycle rate 12 Hertz are converted into resistance data. On test stand reproducible tests with simulated up- and downhill drive, kick-down speed up, switch variants with different gear temperatures etc. may be carried out replacing prescribed road test with integration of test piece into motor car.
Selector regulation:
With selector regulation selector positions may be set from central control room resp. by computer (automatic programs). Selector positions are only released by test stand control when safe selection for test stand and test piece has been checked by corresponding programme routine (e.g. switching from “D” to “R” under load). Regulation is made with power and position control.
Interface test stand/master computer:
25 analogous true values from test stand resp. piece
15 analogous set-point values for test stand control
20 digital I/O signals for transmission/test stand control
Technical data
Test piece drive:
speed 0 – 6000 r.p.m.
torque max. 150 Nm
speed alternation – max. 3000 r.p.m./1 sec.
inertia moment at drive shaft 0.1 kgm2
Test piece power take-off:
speed 0 – 6000 r.p.m.
torque max. 360 Nm/1000 r.p.m.
torque max. 60 Nm/6000 r.p.m.
speed alternation max. 1000 r.p.m./1 sec.
selector regulation:
regulating distance: 100 mm
regulating speed: 200 mm/sec.
actuating power: 150 Nm
accuracy: +/- 0.1 mm
air-conditioning:
Separate control board (19″ slide-in) includes temperature control with digital set-point selector and all control elements needed for the function.
Dimensions assembly:
height: appr. 2055 mm
width: appr. 800 mm
depth: appr. 2090 mm
overall dimensions:
height: appr. 1200 mm
width: appr. 1960 mm
depth: appr. 1200 mm
Test chamber volume appr. 1700 l
Temperature range: 40 C to + 50 C
temperature constancy: +/- 0.1 mm
Bowden-pull regulation:
regulating distance: 100 mm
regulating speed: 50 – 1000 mm/sec.
actuating power: 150 Nm
accuracy: +/- 0.1 mm
Transmission-oil cooler: -40 to 150 °C
coolant: water
