Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
  • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
  • G01L5/28—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for testing brakes
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M13/00—Testing of machine parts
  • G01M13/02—Gearings; Transmission mechanisms
  • G01M13/025—Test-benches with rotational drive means and loading means; Load or drive simulation

Definitions

• the invention relates to an improved brake tester. Furthermore, the invention relates to an optimized method for testing a brake.
• the development times demanded by the market in the automotive sector are getting shorter and shorter.
• the complexity of assemblies of vehicles is increasing. Therefore, in the field of brake technology, test stands have been used for many years, with which new developments can be tested and improved even before the presence of a complete vehicle. These test rigs have the task to provide the most realistic operating conditions for the brake to be tested in order to make safe predictions on the subsequent behavior of the brake in the vehicle can.
• An essential aspect in the simulation of braking processes on a test bench is the kinetic energy of the vehicle. In reality, this energy depends on the driving speed but also on the vehicle weight and the driving situation, such as, for example, cornering or driving on inclines or slopes.
• Brake test stands are known in which the simulated kinetic energy of the vehicle is provided by rotating flywheels.
• the kinetic energy depends on the moment of inertia of the rotating flywheel.
• a disadvantage of such test stands is that different kinetic energies can only be simulated by a change in the rotating mechanical flywheel. This requires mechanical modifications and is therefore not possible during a test run. Without modification of the flywheel, a change in the kinetic energy can be achieved here only by changing the speed. This speaks in most cases the test idea. For example, the difference in braking performance between a horizontal ride and a ride downhill (additional kinetic energy through the slope) would have to be realized downhill in a known brake test bench by increasing the speed in the simulation of the ride. However, this increase in rotational speed on the brake does not occur in reality, so that the simulated test provides no meaningful results.
• the object of the present invention is therefore to improve the conformity of simulated brake tests with reality and thus to make the results determined during the test more meaningful.
• This object is achieved by a method for testing at least one brake, wherein the energy required for testing the brake or the torque required for testing the brake is provided by a drive motor, at least before the test of the brake, a load generator is switched on and the required energy or torque is established or provided by a torque balance between the drive torque of a drive motor and a load torque of a load generator.
• a brake converts previously existing kinetic energy of the vehicle into heat during braking.
• this kinetic energy must be available at the beginning of the braking process in the system.
• the kinetic energy is provided by a drive motor.
• a mechanical flywheel as additional energy storage is not provided.
• the brake to be tested is brought by a drive motor to the desired speed.
• the drive motor operates at this time only against the resistance torque of the open brake, which is very low compared to the braking torque when the brake is actuated.
• the mechanical energy stored in the system is also low due to the low moving masses.
• a load generator is switched on before the braking process.
• This load generator generates an adjustable load torque, which counteracts the drive torque of the drive motor.
• this load torque of the load generator is initially increased continuously.
• the control of the drive motor counteracts this increased load torque with also increased drive torque, the speed of the experimental setup is kept constant.
• the load torque of the load generator is switched off or continuously reduced.
• a particular advantage of the invention is that the change in the kinetic energy is adjusted solely by changing the load torque of the load generator, there are for this no mechanical or structural intervention in the system necessary.
• Such a test method according to the invention also enables the automatic operation of complex test programs for brakes. For example, a real test track with many different consecutive braking processes can be simulated on the test bench. The present at different braking situations, such as gradients or curves, kinetic energy is simply pretend before the corresponding, simulated braking by an adapted load torque of the load generator, introduced into the system and implemented according to the braking of the brake of reality. The inventive method therefore provides a very accurate simulation of the reality in the simulation of braking and thus allows the evaluation of newly developed brakes long before they can be tested on a real test track.
• the load torque of the load generator is increased by the controller before the test of the brake time-dependent according to a ramp.
• the control and regulation of the load torque of the load generator is taken over by an automatically operating control.
• the load torque of the load generator is continuously increased with time until the test of the brake, until the desired load torque for testing the brake is reached.
• the load torque causes an equal, opposite drive torque of the drive motor.
• the increase of the load torque with time can be see functions or ramps match. For example, this increase can be linear, but the method according to the invention is not limited to this linear time function.
• the energy provided by the drive motor in the brake will be converted during the test, whereby the load torque generated by the load generator will be reduced or switched off during the test of the brake.
• the energy provided by the drive motor is converted by the brake. This energy is largely converted into heat.
• the load torque of the load generator is reduced or turned off. This reduction of the load torque results from torque equilibrium, which is necessary to ensure a constant speed of the test stand.
• a previously non-existent braking torque is generated there, which counteracts the drive torque of the drive motor.
• the load torque of the load generator alone counteracts the drive torque.
• the load torque must be reduced by the amount of the braking torque to obtain a constant speed. If the braking torque is the same as the load torque before braking, the load generator is completely switched off. Since torque and energy are physically coupled across speed, system-related energies (kinetic energy of the drive motor, energy converted in the load generator, energy converted in the brake) have equivalent relationships as described for the torque ratio. The energy converted in the load generator is therefore reduced by the amount of energy applied in the brake, after the onset of braking, to remain in equilibrium with the kinetic energy of the drive motor.
• the speed of the drive motor and the load torque of the load generator are controlled by the controller during the test of the brake according to the implementation of the energy to the brake.
• the implementation of a certain amount of energy on the brake is a requirement when testing the brake.
• Other variables in the system such as the load torque of the load generator, drive torque and speed of the drive motor, etc. are automatically controlled by the controller according to the known physical relationships with the applied braking energy.
• the controller processes input signals from various sensors to the corresponding manipulated variables for the components load generator and drive motor, so that the conversion of energy to the brake complies with the specifications of the test task.
• the speed of the drive motor is controlled by the controller until the brake is checked as constant by all the effective torques of the drive motor, the load generator and the brake are kept in balance.
• a constant speed of the drive motor and thus a constant speed of the brake to be tested during the beginning of the braking is important for a realistic simulation. Especially the transition between the effect of the load generator and the activated brake is crucial here.
• the controller relies on the signals from the speed and torque sensors. If the controller recognizes the smallest changes in the rotational speed, control signals are automatically sent immediately to the components load generator and drive motor in order to influence their acting torques and thus to keep the rotational speed of the brake constant through a balance of drive torque, load torque and brake torque.
• the controller has inputs from various sensors. These may be, for example, torque and / or speed sensors. The values determined via these sensors are stored by the controller in a driving simulation memory. Especially torque and speed values in combination with time values allow an accurate evaluation of the processes that take place on the brake during the test. Of course, other data generated during the brake test can also be recorded. Conceivable here, for example, the temperature at various points of the brake or mechanical voltage levels on the brake or its suspension would be. By storing these test data, the tested brake can also be evaluated at another time or, if the data is transmitted via a data interface, at another location. Furthermore, measured values of different brakes or different development levels of brakes can be very easily compared electronically.
• route profile information is stored in the driving simulation memory and the controller determines from this route profile information a time profile of torque and speed which is to be applied to the brake in the test phase after the start of the test and these parameters are applied to the vehicle Drive motor to be transmitted.
• route profile information here stands for a data set that is all for the 4
• the route profile information also includes data relating to the kinetic energy of the vehicle to be converted by the brake, as well as the wheel speed applied at the time of braking. From this line profi linformation, the controller determines the time curve of torque and speed required for testing the brake on the test bench.
• the corresponding control variables for mapping the route profile on the test bench are transmitted from the controller to the drive motor and the load generator and monitored their implementation in a control loop.
• several different route profile information can be stored in the driving simulation memory. This route profile information can then be selected on the controller before carrying out a test method according to the invention. It is thus possible to select and execute a wide variety of simulated test tracks without mechanical modifications.
• a brake test stand comprising at least a drive motor which is coupled via at least one torque transmission device to a load generator and at least one brake to be tested, wherein the drive motor provides the energy or torque to be converted by the brake to be tested and wherein at least prior to testing the brake, the load generator receives the energy provided by the drive motor or the torque provided by the drive motor.
• a drive motor provides the kinetic energy required to test the brake.
• This drive motor is coupled via a torque transmission device in operative connection with the brake.
• This torque transmission device consists in the simplest case of a shaft, but can also be formed by a gear transmission, belt transmission, chain transmission or the like.
• the drive motor has a further operative connection with a load generator.
• This load generator is also connected to the drive motor via a torque transmission device.
• These torque-transmitting devices may be identical to that with which the drive motor is connected to the brake, in the simplest case formed by a continuous shaft. Of course, but also independent of the brake torque transmission direction can be used.
• the load generator is a device which provides different load torques depending on the time. These load te then act, transmitted by the torque transmission device, the drive torque of the drive motor. Rotating flywheels are not provided in the test stand according to the invention, but also not excluded.
• the drive motor turns the brake at the desired speed and only works against the resistance torque of the opened brake, the load generator does not generate any load at this time.
• the energy present in the system at this time is low, since the drive motor only has to provide a low drive torque and no mechanical energy storage, such as a flywheel, is available. If the braking process were suddenly started, the brake would have converted the kinetic energy stored in the system very quickly into heat and the drive motor would come to a halt quickly. In order to provide greater kinetic energy in the system, the drive torque of the drive motor would have to be increased suddenly at the beginning of the braking.
• the load generator biases the drive motor," so that the mechanical energy stored in the system is increased, and it is particularly advantageous in the action of the load generator that the energy in the system can be steplessly adjusted
• the stored kinetic energy is then converted by the brake into heat
• the load generator can be formed for example by a vortex power brake
• different kinetic energy for simulating different driving situations when testing brakes can be easily realized by different timing of a braking current for the load generator even mechanical upplungs- or conversions of flywheels are needed in any way.
• the dynamometer also enables the automatic operation of complex test programs for brakes.
• a real test track with many different consecutive braking processes can be simulated on the test bench.
• the kinetic energy present in different braking situations is simply predefined by the matched load torque of the load generator before the corresponding simulated braking processes, introduced into the system and correspondingly implemented during braking by the brake.
• An inventive brake tester therefore provides a very accurate replica of the reality of different driving situations in the simulation of braking and thus allows the assessment of newly developed brakes long before they can be tested on a real test track.
• the test stand has a controller which has at least one input for the signal of at least one torque sensor and which outputs in each case for driving the load generator, the drive motor and / or the brake to be tested.
• an electronic control is the central instance for the automatic operation of a brake tester according to the invention.
• this control has multiple sensor inputs, are determined via the information on the current status of the test bench.
• An essential input for controlling the automatic operation of the brake tester is the applied torque between the load generator and the drive motor and the torque between the drive motor and the brake.
• additional sensors as inputs to the controller. Such sensors could be, for example, speed, temperature or voltage sensors.
• the controller also has various outputs. These outputs control the operation of the load generator, the drive motor and the brake to be tested. The outputs can affect various physical variables such as the speed and the torque of the drive motor.
• the drive motor of at least one electric DC motor, at least one electric AC motor, at least one internal combustion engine, at least one hydraulic motor or at least one pneumatic motor is formed.
• An inventive brake tester can in principle be driven by motors of different drive concepts. Electric motors offer great advantages in terms of control and regulation. In this case, a variety of types of electric motors can be used such as DC motors, AC motors, synchronous motors or Asynchronous motors. Furthermore, motors with other drive concepts, such as internal combustion engines, hydraulic motors or pneumatic motors according to the invention can be used to drive a brake tester.
• the drive motor is formed from a plurality of partial drive motors, wherein the torques of these partial drive motors act in total on the brake to be tested.
• the drive motor can also be constructed from a plurality of partial drive motors. These partial drive motors are connected to each other so that their drive torques act in total on the brake to be tested. If a relatively small drive torque is required to simulate a relatively small kinetic energy, it is now possible, for example, to operate only a partial drive motor. These other partial drive motors are disengaged or rotate in idle with.
• the load generator consists of at least one eddy current brake or at least one electric generator.
• a load generator according to the invention is provided, which enables the setting of a variable resistance torque which acts against the drive torque of the drive motor.
• devices or generators of various concepts are suitable for this purpose. Devices with electrical principles of operation have proven to be particularly advantageous since they are very easy to control electronically and automatically. Since the load generator is used very often and over a long service life during operation of the test bench, low wear or wear-free concepts are recommended. Very good solutions therefore represent mechanically non-contact eddy current brakes. In this concept, the load torque of the load generator depends on a braking current introduced into the eddy current brake.
• the load generator is formed from a plurality of partial load generators, the load moments of these partial load generators acting in total on the drive motor.
• the load generator is constructed in several parts, the concept is similar as shown above in an embodiment of the drive motor.
• several load generators are coupled to one another in such a way that their load moments act together, ie in total on the drive motor.
• partial load generators For the generation of smaller load moments, a smaller number of activated partial load generators is sufficient; for larger load torques, additional partial load generators are switched on. It is also possible to combine partial load generators of different technical concepts. For example, eddy current brakes could be combined with electric generators. An advantage of a multi-part construction of the load generator is the increased flexibility with respect to the load torque provided. Furthermore, there is a redundancy between the partial load generator, which increases the reliability of the brake tester.
• the controller has a driving simulation memory and the controller controls the load torque or the energy consumption of the load generator and the rotational speed of the drive motor on the basis of the driving data from the driving simulation memory.
• This driving simulation memory is used to provide records for testing the brake. These datasets include requirements for performing the brake test, such as the number of brakes, the timing of the brakes, the duration of the brakes, the wheel speeds applied, and the kinetic energy of the vehicle at the time of the brakes.
• These requirements for brake testing stored in the driving simulation memory are then transmitted by the controller in the form of manipulated variables to the active components of the test bench, namely the load generator and the drive motor. In this embodiment, it is provided that the controller automatically controls these active components of the test bench.
• a speed sensor is attached to the brake to be tested or to the torque transmission device which transmits the torque between the drive motor and brake to be tested, which is connected to the controller.
• This speed sensor allows as input to the controller a comparison of the actual value of the speed with a predetermined setpoint. If deviations between these two values occur, the controller influences the system so that the deviation is eliminated again.
• the driving simulation memory has a data interface for the data import and export. By means of such a data interface, determined test data can be exported after carrying out a brake test and evaluated or processed elsewhere. Thus, it is possible, for example, to transmit large quantities of test data directly to a customer.
• specifications for checking brakes in the driving simulation memory can be imported.
• route profile information is determined or generated at another location and then simulated by importing to a brake test bench according to the invention. This leads to a significantly increased flexibility with respect to various test programs, which can be so quickly and easily selected or replaced.
• the test stand further comprises a climate chamber, in which the brake to be tested is housed during the test.
• a climate chamber in which the brake to be tested is housed during the test.
• the placement of the brake to be tested in an optional climatic chamber enables the simulation of additional test parameters. Temperature and humidity values that can be set in the climate chamber can be used to simulate different climatic conditions when testing the brakes.
• these climatic conditions can also be automatically influenced and changed by the central control, furthermore, the actual climate data can also be recorded time-dependent in the driving simulation memory together with the other test data. Effects of the climatic conditions on the braking behavior can be seen very well on this database.
• the climatic chamber has a spray head which sprays the brake to be tested.
• the brake to be tested for example, be moistened during the test.
• the spray head is not limited to liquids. It is also possible to apply powder or gas to the brake. This allows the simulation of dust or noxious gas pollution, thus contributing to the realistic simulation of complex environmental and operational conditions of brakes.
• the central control of the brake test stand also uses the operating parameters of the spray head and records these in the driving simulation memory. Of course, it is also possible to deposit nominal values for the operation of the spray head in the form of data within a route profile information.
• the invention also encompasses the use of a brake test stand according to the invention for the purpose of carrying out a method according to the invention.
• Fig. 1 is a schematic representation of a brake tester according to the invention
• Fig. 2 is a diagram showing the torque over a time axis according to a method of the invention.
• Fig. 1 shows a schematic representation of a brake tester according to the invention.
• the test piece 4 is connected to the drive motor 1 via a torque transmission device 2.
• the torque transmission device 2 is formed by a shaft.
• the torque can also be transmitted by means of other transmissions, such as gear transmissions, belt transmissions or chain transmissions.
• the load generator 3 is shown, which is also coupled via a torque transmission device 2 to the drive motor.
• the torque transmission device between the load generator and the drive motor can also be embodied in various ways.
• the controller 5 has connecting lines to the sensors 6, 1, 19, which represent inputs to the controller.
• the torque sensor 6, which is arranged between the drive motor 1 and the load generator 3 and measures the generated load torque of the load generator 3, is connected to the controller 5 via connection 15.
• the connecting line 17 closes the torque sensor 7 and the rotational speed sensor 19, which are located between the drive motor 1 and the DUT 4 and measure the braking torque of the brake 4 and the rotational speed of the brake 4, to the controller 5.
• the control has several outputs:
• the connecting line 14 allows control of the load generator 3, the drive motor 1 is controlled by line 16 and the brake to be tested 4 is connected via the control line 1 1 to the controller 5.
• the controller 5 also has a data connection to the driving simulation memory 10.
• This driving simulation memory 10 records during the test of the brake 4, the input data of the sensors 6, 7, 19, and the manipulated variables of the control of the components load generator 3, drive motor 3 and 4 brake. This recording of the data takes place in each case in combination with a time stamp. The data stored in this way can later be used for the reproducible evaluation of the tested brake.
• the driving simulation memory 10 has a data interface 18 for importing and exporting data. In addition to exporting test data and measured values, it is of course also possible to import data. Thus, route profiles can be loaded into the driving simulation memory 10, which are based on a real test drive, for example on a race track.
• route profiles can contain, for example, value pairs of required kinetic energy and the time points or time periods at which braking takes place.
• the data interface 18 allows a very rapid changeover of the test between different routes to be simulated and driving situations.
• the optional climate chamber 8 can be seen on the right side, but not necessarily for a brake tester according to the invention is required.
• the brake 4 to be tested is located inside this climatic chamber 8.
• the climate chamber 8 is connected to the controller 5 via the data link 13.
• the climate chamber, as well as the other components of the test stand be controlled centrally by the controller 5 automatically.
• a spray head 9 is mounted in the climatic chamber 8. It is possible to spray the brake 4 during the test, for example with water, so as to simulate a wet road.
• the spray head 9 is not limited to liquids. It can also be passed to the brake powder and gases and applied to simulate, for example, dusty or harmful gas contaminated environmental conditions.
• the spray head 9 is connected via the data line 12 to the controller 5, so that all the functions of the automatic control and the integration into route profiles in the simulation are also available for the spray head 9.
• FIG. 2 shows a diagram in which the quantity of torque (M) is shown over a time axis (t).
• the diagram represents the time sequence of a test procedure according to the invention for brakes. Upwards, the torque is plotted, which is stated as a percentage with respect to the maximum torque of the system.
• the horizontally extending time axis is labeled with relative time steps, the time periods of the various process steps may of course also have different ratios to each other in different simulations and tests.
• the test stand is idle.
• the drive motor rotates the brake to be tested with the speed specified by the simulation program.
• the drive motor works only against the very low resistance torque of the open brake and therefore requires only a very low drive torque to maintain the speed.
• Fig. 2 Decisive for the understanding of Fig. 2 is the beginning of the braking, which is represented by a vertical dash-dot line 21.
• the braking thus begins here at time step 13.
• the load generator is now switched on according to the invention already before the start of the braking. This is done in the illustration in Fig. 2 already at time step 10.
• the load torque of the load generator is then increased continuously, which is represented by the ramp 20 in the diagram.
• the time of the connection of the load generator, and the slope of the ramp 20 to increase the load torque with time are chosen so that at the beginning of the braking 21, the desired load torque is available.
• the start of the braking 21 corresponds to the kinetic energy in the system of the test bench of that kinetic energy of the driving situation to be simulated.
• the two physical quantities kinetic energy and torque or load torque are linked together via the rotational speed.
• the variables wheel speed and kinetic energy of the situation to be simulated on the test bench are known.
• the speed of the test object is set according to the specification.
• the load torque of the load generator is then increased until the beginning of braking 21 until the desired kinetic energy is present in the system.
• This kinetic energy results from the product of speed and load torque or the same large drive torque.
• the two quantities or terms kinetic energy and torque are thus physically coupled and to use descriptions or explanations in the same sense.
• Fig. 2 the time range of the actual braking operation is shown by the arrow 23.
• the dashed line 22 shows a possible course of the braking torque during the test.
• This chronological course of the braking torque is dependent on the driving situation to be simulated and therefore only shown here by way of example.
• the braking can either be ended, and thus all acting torques are reduced to almost zero, which then corresponds again to a state of the system as in time step 1, or it can be on the first braking directly following further braking possibly other speed or kinetic energy. In doing so, the required kinetic energy is again introduced into the system before the next braking with the help of the load generator.
• the inventive method is thus adaptable to a variety of simulation projects.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
• Regulating Braking Force (AREA)
• Testing Of Engines (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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• 2014
  • 2014-11-14 DE DE102014116714.7A patent/DE102014116714B3/de active Active
• 2015
  • 2015-11-04 JP JP2017544824A patent/JP6783779B2/ja active Active
  • 2015-11-04 US US15/526,474 patent/US10267698B2/en active Active
  • 2015-11-04 EP EP15790468.1A patent/EP3218683B8/de active Active
  • 2015-11-04 CN CN201580061959.9A patent/CN107003195B/zh active Active
  • 2015-11-04 WO PCT/EP2015/002224 patent/WO2016074777A1/de not_active Ceased

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