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Passenger Car Assemblies

Passenger Car Assemblies

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Camshaft Test Bench

Assembly Line for Cylinder Heads

Friction Performance Test Bench for Engines

Task:

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.

Solution:

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.

Failure signals:

  • oil level
  • thermal cut-out
  • pressure switch
  • circulating pump
  • oil pump
  • oil filter
  • pressure switch supply
  • pressure switch cooling water
  • total failure signal at test rigs

During normal operation all failure signals lead to cut-out of plant.

With digital technique and display following parameters are measured:

  • working hour counter
  • temperature (circulating pump or test piece feed)
  • feed temperature
  • test piece temperature
  • speed
  • torque

Air-condtioning chamber

[Picture Machine]

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.

Operation part

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.

Technical data

Unit dimensions:
height appr. 1850 mm, width appr. 1500 mm, depth appr. 1000 mm

test chamber vol.: appr. 950 l

overall dimensions:
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

Engine Test Bench, Mobile, for Complete Vehicles

Task:

A test stand had to be developed for testing engines of up to 150 kW.

The following aspects had to be taken into account:

  1. The test stand has to be mobile.
  2. The engine has to be linkable to the test facility in such a way that any engine could be flange-mounted after changing a mounting rest (total of 15 types).
  3. The clamping unit must be quick and easy to operate.
  4. The test stand has to be rated for a load of up to 7500 rpm
  5. The engine and hydraulic brake must be linked by a commercially available clutch, and the engine and brake must be easily disconnected, i.e. a rapid separation must be possible.
  6. The engine must be capable of starting without an external starting aid.
  7. The engine must be able to be held at the front by a quick-adjusting support.

The test stand must be capable of the following test jobs:

  • Performance measurement (torque, speed)
  • Oil temperature (inlet and outlet temperature)
  • Water temperature (inlet and outlet temperature)
  • Consumption measurement
  • Control characteristcs
  • Driving

Solution:

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:

  • a hydralic brake, made by Schenck, model D 2101 E
  • a measurement and control unit for the oil temperature, supply and return lines
  • a measurement and control unit for the water temperature, supply and return lines
  • a fuel consumption measurement unit
  • measuring technology permitting operation of 4 different performance measurement programs
  • efficiency measurement unit

Transmission Test Bench

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

Test Stand for Synchromesh Gearboxes

Task:

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.

Solution:

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:

  • Tilting base with clamping plate for a test box or compete gearbox
  • Driveline with torque measuring point and flywheel
  • Oil supply unit
  • Gear shifting unit with separate hydraulic fluid supply
  • Ambient air heating and cooling unit
  • Insulated test chamber
  • Test box
  • Loading unit for test box
  • Means of calibrating torque measuring shaft in driveline
  • Drive motor
  • Switchgear cabinet for power pack
  • 19″ cabinet for measuring and control modules
  • Control panel
  • Computer for measured data acquisition

Control panel

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.

Hydraulic Positioning Unit

Task:

  • Hydraulic linear forward feed with electric minimal and maximal displacement limitation.
  • Advance speed to be steplessly variable.
  • Permanent position control over total feed range.
  • Free selection of push and pull force; max./min. value control.

Solution:

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.

Use:

  • Switchgear for gear test stands (gearbox, automatic transmission)
  • Accelerator pedal
  • Integration into program demanding defined selection of valves resp. gates

Technical Data:

speed: steplessly variable from 0.1…..1m/s
positioning accuracy: +/- 0.1 mm
positioning control: +/- 0.2 mm
displacement measuring system: inductive