Background art With driving motors of motor vehicles, it is very important to know variations of delivered torque and power, respectively in dependence of the rpm (revolution per minute) value of the crankshaft. Generally, motor performance is examined by means of so-called motor testing stands, under laboratory circumstances. In most of the cases the motor is separated from the motor vehicle for the time of testing. During the test procedure, the motor is started and operated until reaching of the working temperature.

Thereafter, the rpm of the unloaded motor is raised near to the maximum value. Then the motor is gradually braked down by means of an external loading machine (e. g. hydraulic pump). Gradual braking down is accomplished by increasing the braking force unit by unit; always waiting until the rpm of the motor is stabilized i. e. the fixed working point is achieved. For each working point, torque delivered by the motor together with the corresponding rpm value further the fuel consumption will be recorded as so-called primary data. As secondary data, temperature of the cooling liquid, temperature and composition of the exhaust gas, pressure and temperature of the lubricating oil, further the outside atmospheric pressure and temperature and vapour content of the external air will be checked and recorded for the sake of security.

The above measurements will be accomplished for the whole range of rpm of the motor. Using the primary data effective power and torque value be computed for each working point. Corresponding data will be plotted in dependence of the rpm of the motor in form of so-called external characteristics.

Place and mode of the loading (braking) may vary with individual known testing methods. The braking can be static or dynamic and can take place for example on the crankshaft, on the-torque converter or on a wheel. It is accomplished, however, always by means of an external equipment (so-called braking machine).

Main disadvantage of the said known solutions is in it, that the motor vehicle has to be brought into a laboratory fitted with a braking stand indispensable in order to complete the examination thereof. Moreover, an appropriate braking stand is rather expensive. Obtaining of power and torque characteristics and determining of working points, respectively require accomplishment of a lengthy series of measurements. It is a further drawback that attained data are place and time dependent, i. e. they reflect parameters characterizing the tested motor exclusively at individual place and time of the examination, under"sterile"laboratory circumstances. In case of altering certain adjustments of the motor vehicle or of natural changes of characteristics of the motor vehicle due to normal wear, actual power and torque data could only be detennined by repeated carrying out of the whole measurement sequence.

Known solutions do not permit the driver to inspect during use variations of motor power and torque, albeit such controlling would be very useful, especially in case of racing where substantial decrease of the power as compared to the expected value can signalize a serious technical defect which in given case could endanger even the racer himself.

HU-PS 191 055 describes an apparatus for measuring of motor torque, wherein a strain gauge (strain-measuring label), a supply unit and a signal transmitter are fixed onto the shaft to be loaded and a signal receiver together with an electronic signal processor unit are fastened to the standing part. In case of loading torsion of the shaft occurs and the electrical resistance of the strain gauge changes. The change of the resistance being proportional to the loading, the torque delivered by the shaft can be determined by means of measuring the said change of resistance. Although this known solution can be used for measuring torque during operation of the motor, coupling out of the signals from the rotating part can be accomplished only b intricate means subject to defects. Application, maintenance, repair and protection against dirt thereof can be difficult in given cases e. g. with motor cycles. It is a further disadvantage that arrangement of the supply unit and/or of the signal transmission unit can be difficult or even impossible in certain cases e. g. with motor cycles.

Object of the present invention is to create a method of and an apparatus for measuring working parameters, especially torque and/or mechanical power of driving motors of motor vehicles which method and apparatus do not require coupling out of measuring signals from a rotating part, and make thereby the measuring simpler and more widely applicable and the apparatus for realizing the said measurement becoming less expensive and more reliable.

Summary of the invention The present invention is based on the idea that the torque delivered by the motor and the counteracting load produced by the resistances of travelling (air resistance, friction resistance, accelerating and hoisting resistance) cause deformation on a number of statically rigid parts of the motor vehicle as well. Under the effect of the torque used up in order to overcome the travelling resistances, those statically rigid parts behave according to the Hook law i. e. a mechanical tension proportional to the relative deformation arouses in them. To the said statically rigid parts count both moving and fixed parts. Such moving parts (e. g. half shaft of the carrying system) take part directly in transmission of the torque delivered by the crankshaft of the motor. Although fixed parts (e. g. the frame extension for sustaining the motor, further the hinging arm of the carrying system) do not take part directly in the transmission of torque, measuring of the deformation raised on them is equally appropriate to achieve the aimed goal since deformation of the said statically rigid parts is always directly proportional to the load put on them the latter in turn being directly proportional to the torque delivered by the motor.

On the basis of the above recognition, the above problem is solved on one hand by a method of measuring working parameters, especially torque and/or mechanical power of driving motor of a motor vehicle, wherein the motor is start to working temperature, then torque values of the motor produced at different rpm values are determined during varying the load of the motor; and wherein determining the torque values produced by the motor is accomplished according to the present invention during operation of the motor vehicle by means of measuring of deformation of a statically rigid part-preferably frame, frame element, motor sustaining element, carrying system, pivoting arm, half shaft-of the motor vehicle.

Preferably, measuring of the deformation is accomplished by means of a strain gauge and/or a piezoresistive element fastened onto the said statically rigid part.

With a preferred mode of realization, instantaneous power values of the motor are computed on the basis of corresponding torque and rpm values and in given cases said power values are displayed and/or recorded.

On the other hand, the above problem is solved by an apparatus for measuring working parameters, especially torque and/or power of driving motor of a motor vehicle, the apparatus having a means for measuring the torque delivered by the motor and in given cases a means for measuring the rpm value of the motor ; wherein according to the present invention the means for measuring the torque delivered by the motor is an element appropriate to measure deformations suffered by a statically rigid part-preferably frame extension, motor sustaining element, pivoting arm, half shaft-of the motor vehicle, expediently a strain gauge and/or a piezoresistive element fastened onto the said statically rigid part.

With a preferred embodiment, the means for measuring deformations- preferably the strain gauge and/or piezoresisitive element fastened onto the said statically rigid element-is connected to an input of a signal processing main unit, known per se, arranged on the motor vehicle.

Preferably, the main unit has a further input connected with a tachometer, which is coupled to the motor of the motor vehicle.

In a particularly preferred embodiment, the apparatus according to the present invention has a power displaying unit and/or a torque displaying unit and/or a recording unit each connected to an output of the main unit.

The present invention makes it possible to inspect continuously power and torque delivered by driving motors of motor vehicles in a fast and in By using the invented solution, the motor can be adjusted precisely also on remote places near racing roads far away from service sites. Declining of the power will timely signalise the driver that a defect of the motor is imminent. The disclosed solution is also appropriate to check exploitation and economy of operation of the motor and makes possible even posterior determination of eventual overloading as well. Using an appropriate recording system working history of the motor can be analysed as well.

Thus e. g. warranty claims can be judged more easily. Study of the registered data can be useful in examining of driving abilities as well.

Brief description of the drawings Below, exemplary embodiments of the method and the apparatus according to the present invention will be described with reference to the accompanying drawings in which Fig. 1 shows a schematic view of a motor cycle fitted with a measuring apparatus according to the present invention; Fig. 2 shows the block diagram of the measuring apparatus; and Fig. 3 shows a schematic view of a part of a motor vehicle fitted with a measuring apparatus according to the present invention.

Detailed description of the preferred embodiments Fig. 1 shows a part of frame structure of a motor cycle in schematic side elevation.

Motor block 1 of the motor cycle is fastened to a bridge structure 3 and a frame extension 2 thereof. A strain gauge 4 is fastened to the frame extension 2. Two output ends A, B of the strain gauge 4 are connected to an input. of a measuring unit (not shown).

After starting the motor of the motor cycle the vehicle is moved ahead. As a result thereof, the statically rigid frame extension 2 not taking part directly in the force transmission between the motor and the wheels (not shown) but being exposed to the loading originating from the torque delivered by the motor in ordt motion resistances will suffer a deformation (strain). Measure of the deformation is proportional to the torque delivered by the motor. Thus the strain gauge 4 attached to the frame extension 2 and strained together with the deforming frame extension 2 will show a change of resistance proportional to the measure of the strain. This change of resistance can be measured, recorded and/or displayed by means of modes known per se. From the measured value corresponding data relating to the torque delivered by the motor can be obtained by calibration. With simultaneous measuring by known methods of the rpm of the motor we can determine the torque delivered by the motor in a given moment, again using known methods.

Fig. 2 shows block diagram of an apparatus suitable for measuring, displaying and recording of torque and/or power delivered by driving motor of a motor vehicle.

The apparatus has a main unit 10 with an input unit 11. To the input unit 11 one or more strain gauges 4 and a tachometer 8 are connected. Outputs of the input unit 11 are connected via signal filtering and forming unit 12 and amplifier unit 13 to an input of a computing unit 14. An output of the computing unit 14 is connected via output unit 15 to a power displaying unit 17, a torque displaying unit 18 and a recording unit 19. Units II... 15 are interconnected with supply unit 16 as well. Power supply of sensors, displaying and recording units is realized by using known schemes.

The method of the present invention is accomplished by means of the apparatus according to Fig. 2 as follows : After starting the motor of the motor vehicle the latter is moved ahead. Loading of the vehicle originating from the resistances of travelling (to be counteracted by the motor by way of delivering at a given rpm a corresponding amount of torque and power, respectively) will cause deformation of certain statically rigid parts (e. g. frame, frame extension, half shaft etc.) of the motor vehicle. An electrical parameter (e. g. the electric resistance) of the strain gauge 4, or of a piezoresistive element or of any other suitable means for measuring deformation (not shown) will suffer a change proportional to the measure of the said deformation. An electric signal varying in accordance with the said electric parameter will be forwarded via input unit 11, signal filtering and forming unit 12 and amplifier unit 13 to computing unit 14. Using schemes knownper se, computing unit 14 determines the torque values corresponding to the mome deformation. Computed values of torque are then forwarded to torque displaying unit 18 and torque recording unit 19. The latter units are calibrated (again by using known techniques) in a manner that measured values will be displayed and recorded in torque measuring units.

Simultaneously, tachometer 8 measures the rpm values. Corresponding electrical signal is forwarded again via input unit 11, signal filtering and forming unit 12 and amplifier unit 13 to computing unit 14. On the basis of corresponding torque and rpm values computing unit 14 determines (again using known techniques) instantaneous power values. The latter are forwarded to power displaying unit 17 and power recording unit 19, respectively. The said units are calibrated (again by means of known schemes) in a manner to display and/or record computed values directly in power measurement units.

The described apparatus makes it possible to determine characteristics of the driving motor of the motor vehicle under circumstances of working. For this aim the motor of the motor vehicle is started and warmed up until operating temperature.

Thereafter moving ahead of the motor vehicle is initiated and the motor is accelerated up to the maximum value of its rpm or near to that point. The statically rigid part of the motor vehicle, which is fitted with a strain gauge (or with another appropriate sensor), will suffer a deformation proportional to the torque-momentarily delivered-by the motor. Resistance value of the strain gauge 4 will change in accordance with the extent of the deformation. Torque and rpm data will be processed, displayed and recorded by the main unit 10 as described above. Power, rpm and torque data corresponding to each other measured or computed during gradual braking down of the motor vehicle will be recorded by means of the recording unit 19. Thus characteristic diagrams of the motor related to its operating circumstances are obtained.

Fig. 3 shows an example of using a strain gauge for determining instantaneous torque values during operation in case of automobiles. With this example on each one of half shafts 7 of driven wheels of an automobile (not shown in details) strain gauges 4 are fastened. Each strain gauge 4 is connected to a signal transmitter 5. Signal transmitters 5 are fixed onto a corresponding half shaft 7 and are in operating connection with a signal receiver 6 each, the latter being fastened standing part each in the vicinity of the half shafts 7. Operation of this system is similar to that of the above described one, the only difference being in it that variations of resistance values of strain gauges 4 are forwarded to the main unit 10 indirectly via signal transmitters 5 and signal receivers 6.