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Test rigs serve to investigate influences of different construction features of engine component parts on engine friction energy. Single engine parts (valve drive, camshaft, crankshaft drive etc.) are mounted on test piece clamping device and driven by motor. Single parts as well as complete 6-cylinder engine block may be mounted.
Torque is measured by torque measuring shaft. Test piece may be tested from idling speed to driving speed 7,000 r.p.m. Change of speed may be effected either manually with potentiometer or through four preselectable ramps. With automatic operation speed programme may be selected by computer.Computer evaluates and stores speed and torque data.
Driving-engine performance is 47 kW.Test rigs include oil sypply assembly to be switched in when needed. Oil supply assembly supplies test piece with oil of temperatures between 20 and 135°C.
Two different friction test rigs were constructed with central control from control board. Main differences between test rigs are driving power and mechanical construction. Whereas mounting plate of first test rig is steplessly variable over 400 mm, the other’s mounting plate is fixed. Accuracy of mounting plate is acc. DIN 876, quality 3. Dimensions are 800 x 600 mm.
During normal operation all failure signals lead to cut-out of plant.
With digital technique and display following parameters are measured:
Air-conditioning unit construction
Circulating-air-conditioning unit consists of compact-type cabinet. Lower part holds refrigerating unit, in upper part air-conditioning system is installed. Test chamber connection is made by flexible, insulated tubes. Test chamber consists of 120 mm insulated elements, some fixed to test stand and others removable for inspection. Air-conditioning unit is designed for heating speed 2 Grad C/min., cooling speed 1 Grad C/min. and test piece weight 60 kg.
Separate operation rack (19″) is connected with unit by plug-in cable (20 m). It holds temperature control with digital set-value selector and digital true-value indication, ON/OFF switch, function control lamps and failure indication.
height appr. 1850 mm, width appr. 1500 mm, depth appr. 1000 mm
test chamber vol.: appr. 950 l
height appr. 1400 mm, width appr. 1100 mm, depth appr. 1200 mm
temperature range: – 30 to + 120o C
temperature constancy: +/- 2.0o C
water cooled refr. unit: 6 kW
refrigerant: R 502
mains supply: 220/380 V/50 Hz
connected load: appr. 25 kVA
A test stand had to be developed for testing engines of up to 150 kW.
The following aspects had to be taken into account:
The test stand must be capable of the following test jobs:
The test facility was constructed on a rectangular-tube frame with 4 locking spindles and with rubber wheels during transportation.
In the centre section the structure for the measuring shaft, the bearings and the clutch is provided.
A bayonet fastener has been fitted in the outer section of the clutch bearings, using which the respective mounting plate is attached. This ensures that all loads with the exception of that from the engine output are passed onto the structure and so permits unimpaired measurement.
The hydraulic brake is connected to the measuring shaft by a cardan shaft on the rear.
A supporting device is provided on the test engine side. The device is adjustable in the X, Y, and Z axes.
The following units have been installed for performance measurement:
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.
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.
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:
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.
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.
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:
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.
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.
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
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.
regulating distance: 100 mm
regulating speed: 200 mm/sec.
actuating power: 150 Nm
accuracy: +/- 0.1 mm
Separate control board (19″ slide-in) includes temperature control with digital set-point selector and all control elements needed for the function.
height: appr. 2055 mm
width: appr. 800 mm
depth: appr. 2090 mm
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
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
To test gearbox components and complete gearboxes at different ambient temperatures and determine torque, shifting force, input and output speed.
To test the relative movement of the synchronizer rings while shifting a pair of gears (1st and 2nd gears). To apply predetermined braking torques ba means of a loading unit.
To measure the input and output speeds as well as the differential speed, shifting force, selector fork friction moment, synchronising torque, synchronizer ring movement and gear lever movement while shifting gears and evaluate the measured data by means of a computer.
To simulate the real-life force applied by the coasting vehicle by installing a flywheel behind the electric motor.
The task was solved by fabricating a tilting base and equipping it with a clamping plate provided with slots for mounting an angle plate to which the gearboxes to be tested can be secured with bolts.
The test stand essentially consists of:
The control panel is installed in the 19″ cabinet.
Computer for measured data acquisition
A computer is used for measured data acquisition and evalation.
A printer provides hard copy printouts. An interface card transfers the digital values to the computer.
The software provided for the stored-program control system affords a high degree of operator convenience in manual operation.
In the automatic mode, control is assumed by the computer. The scanning rate during measurements is 500 Hz.
Description of the individual components:
Test stand base with clamping plate for mounting a test box or complete gearbox. The test stand base is supported on a rugged tubular frame and tilts max. 5� to one side.
The clamping plate for the test box is provided with T-slots and suitable sealing lips around the circumference for the cooling box.
Design and accuracy of the clamping plate conform to the applicable DIN standards.
The entire surface of the top of the test stand base is machined to Grade 3, DIN 876.
The main drive motor is installed in the base of the test stand and operates at 3,000 rpm, providing a maximum input shaft speed of approx. 5,000 rpm.
Test stand base with clamping plate for mounting a test box or complete gearbox
The driveline is mounted on an adjusting plate in the centre of the test stand, permitting accurate adjustment in all three axes.
The flywheel is installed between two bearings and adequately balanced and stabilized for high speeds.
The input shaft is dynamically balanced (Grade G 2.5 to VDI Specification 2060).
Oil supply unit
The oil supply unit supplies the gearbox with oil heated or cooled to the desired temperature.
The hydraulic unit permits operating temperatures between 20 and 150°C.
The maximum system pressure is 10 bar. The heating system permits the use of oil with different viscosities.
The complete oil supply unit designed for operation at extreme temperatures and with different types of oil.
The time required for heating-up to a temperature of 159°C is approx. 60 minutes.
Safe control is assured by a temperature limiting device with unlocking button in accordance with VDE specifications for 0°C to 250°C. The complete oil supply unit is mounted on wheels.
All oil circuit and hydraulic components meet the most exacting requirements of hydraulic engineering.
Movements are controlled hydraulially and monitored by means of two force and position transducers.
The measuring amplifiers and control modules for the gear shifting unit are housed in the 19″ cabinet.
The gear shifting unit is equipped with RS 232 serial interfaces for connection to the stored-Program control system, connection to the computer and for programming the system via manual input.
Minimal and maximal displacment may be selected independently with special regulator.
Regulating range of min. displacement is 0-50% of total travel.
Regulating range of max. displacement is 50-100% of total travel.
speed: steplessly variable from 0.1…..1m/s
positioning accuracy: +/- 0.1 mm
positioning control: +/- 0.2 mm
displacement measuring system: inductive