WO1995023957A1

WO1995023957A1 - A method and an apparatus for measuring the power or torque of a vehicle

Info

Publication number: WO1995023957A1
Application number: PCT/DK1995/000099
Authority: WO
Inventors: Jesper Ankersen
Original assignee: Jesper Ankersen
Priority date: 1994-03-02
Filing date: 1995-03-02
Publication date: 1995-09-08
Also published as: AU1756395A

Abstract

When measuring the power or torque of a vehicle the velocity or speed of the vehicle while driving on a road and accelarating in a certain gear is recorded at certain time intervals or time increments, and on the basis of the velocities recorded during accelaration the change during the said time interval or time increment in the kinetic energy of the vehicle during acceleration is determined, whereafter the change in power during acceleration in the said time interval or time increment is determined. Correspondingly, the velocity of the vehicle while driving on a road and decellerating in the same gear as when accelerating, or possibly declutched, is recorded at certain time intervals or increments, and on the basis of the velocities recorded during deceleration the change in the kinetic energy of the vehicle during deceleration in the said time interval or time increment is determined, whereafter the change in power during deceleration in the said time interval or time increment is determined. Subtraction of the change in power during deceleration from the change in power during acceleration provides a measure of power representing the power of the vehicle without loss in the transmission of the vehicle, and a subsequent conversion of the measure of power optionally provides a measure of torque.

Description

A method and an apparatus for measuring the power or torque of a vehicle.

The invention relates to an apparatus and a method for measuring e.g. the following performances in cars:

A. h.p. or k on the flywheel of the engine, from idle to top rpm., shown as a graph.

B. Nm on the flywheel of the engine from idle to top rpm., shown as a graph.

C. Acceleration shown as table and/or graph.

D. Acceleration in various gears shown as a table and/or graph.

E. Top speed.

F. Speedometer variations for each velocity interval, e.g. 10 km ph shown as a chart or bar diagram.

G. Wind resistance or road friction shown as a graph.

The apparatus and the method according to the invention replaces the traditional "Rolling Road" which takes a stationary installation in a building and a separate power installation. Such a rolling road is very expensive and needs a skilled operator. The car to be measured is fixed¬ ly mounted with its wheels resting on rollers with controlled brakes. A fan is mounted in front of the car in order to provide sufficient air for cooling. The rolling road measures the power of the engine (h.p. and Nm) and speedometer variations, but normally not top speed, acceleration and wind resistance and road friction. A traditional rolling road does not form part of the ordinary equipment of a repair shop.

The characteristics of the apparatus and the method according to the in- vention appear from the appended claims.

The invention enables most repair shops and other users to purchase the measuring equipment since the purchase and maintenance costs constitute only a fraction of similar costs of a rolling road. Furthermore, the equipment may be adapted in conformity with the method according to the invention. Excluding the computer it may weigh less than 5 kg and may be accomodated in an ordinary attache case. With help from a detailed ma¬ nual operation of the equipment is simpel . Installation of the equipment takes only a few minutes. The measurement is made on a straight, level road length of approximately 1 km. A complete measurement will take three run-throughs. Disassembling of the equipment will take 3 to 5 mi¬ nutes and calculation and printing will typically last 10 minutes. The measuring accuracy of the equipment is < ±5%.

Theoretical basis:

A velocity is measured with intervals of 1/10 sec. The velocity is stored in the computer. During calculation the difference between two velocities is converted into a power measure by means of the following formulae:

e_kin- 1/2 ■ V²

This is a joule, and since joule = watt/sec. the following formula may be derived:

W = (V_j2- v_Q2)m / (2000 t)

The test driving is performed as follows: The car is accelerated from idle to top speed in the highest possible gear. Then you declutch and let the car roll until it has decelerated to the starting speed.

Presupposing that the road is level and the wind constant the following applies:

The road and gear friction and the wind resistance are identical during acceleration and deceleration.

Consequently, the following forces work during acceleration:

KW mes.acc = KW engine - KW wind+friction

and during deceleration:

KW mes.dec. = KW wind+friction

The following may be deduced: KW engine = KW mes.acc + KW mes.dec

As one kW is defined at 20" C and at a pressure of 1013 millibars cor- rection is made in accordance with temperatures measured and according to the formula:

Kwkor = Kw(1013/air pressure)*Sqr((273+air temperature)/293)

Nm is calculated according to the formula:

Nm = Kw 9550 rotations

The invention will now be described in greater detail with reference to an embodiment which in a purely exemplifying way serves to describe the components which may be used when working the invention.

In the drawing

Fig. 1 shows a schematic measuring setup showing the electrical connec¬ tions to and from a measuring disc mounted on a wheel of a car,

Fig. 2 shows the measuring disc of Fig. 1 in greater detail,

Fig. 3 shows the measuring disc of Fig. 2 with a sensor unit mounted thereon,

Fig. 4 shows the structure of a measuring unit consisting of the measu- ring disc and sensor unit shown in Fig. 3,

Fig. 5 shows the mounting of the measuring unit of Fig. 4 on a wheel of a car,

Fig. 6 shows an alternative method of mounting the measuring unit of Fig. 4,

Fig. 7 shows the components of the signal converter shown in Fig. 1 Fig. 8 shows a graph of the electric circuit of the signal converter shown in Fig. 1, and

Figs. 9 to 18 show graphs and displays made by means of the apparatus according to the invention.

Fig. 1 of the drawing shows an emdodi ent of a system setup for use when excercising the measuring method according to the invention. In the fi- gure the reference numeral 8 is a wheel of a vehicle the power, accele¬ ration, speedometer, or wind resistance and road and gear friction of which is to be determined. At the wheel 8 a measuring disc 10 with a sensor 12 is mounted in a manner to be described in greater detail be¬ low. By means of a cable connection 16, which may particularly be a four-wire cable, the sensor 12 is connected to a signal converter 14 which may be placed close to the measuring disc 10 or at a distance therefrom, for instance in the driver's cab of the vehicle. The signal converter 14 is supplied by means of a cable connection 18 which may particularly and suitably at its end be provided with a jack 24 for con- nection to a cigar lighting device in the driver's cab of the vehicle. By means of a further cable connection 20 the signal converter 14 is connected to a computer unit, such as the portable computer unit 22 shown in the drawing. The cable connection 20 is connected to the paral¬ lel printer gate of the computer unit 22 in any suitable manner.

During use of the measuring setup according to the invention the com¬ puter unit 22 records data which are processed for display. If a printer is connected to the computer unit 22 all graphs, tables, etc. may be printed out.

Fig. 2 shows in greater detail a measuring disc 10 for use in working the invention. The measuring disc 10 is made of stainless steel plate and has a circle of punched-out rays around its centre. For mounting the measuring disc 10 at a wheel 8 of a car, punched-out slots 5 placed in a circle are formed.

Fig. 3 shows a sensor unit 12 mounted on the measuring disc 10. The sen¬ sor unit 12 consists of an aluminum disc on which an optocoupler 13 is mounted. The sensor unit 12 itself is mounted on the measuring disc 10 in such a manner that the disc may freely rotate with the wheel, the sensor unit itself being kept in place by means of a steel wire device 6 (vide Fig. 1).

Fig. 4 shows in greater detail the structure of a measuring unit con¬ sisting of the measuring disc shown in Figs. 1 to 3 and a sensor unit with an optocoupler. In addition to the measuring disc 10 and the sensor 12 the measuring unit consists of a reflector 26 placed on the side of the measuring disc opposite to the sensor unit, the said components be¬ ing assembled by means of a bolt 28 extending through the sensor unit 12, the measuring disc 10, and the reflector 26, the said components be¬ ing locked togther by means of a self-locking nut 30. A felt washer 32 may be arranged between the sensor unit 12 and the measuring disc 10.

Fig. 5 shows in greater detail a method for placing or mounting the mea¬ suring disc at a wheel of a car. As shown, a number of metal claws 34 gripping around the wheel bolts or the wheel nuts 36, respectively, may be used for the mounting. The claws 34 are fixed to the wheel nuts 36 by means of a bolt 38 extending through a slot 5 in the measuring disc. As shown in Fig. 6 sleeves 40 may further be used in connection with 19 mm and 17 mm wheel bolts/wheel nuts 36.

Fig. 7 shows the structure of the signal converter 14 shown in Fig. 1. The signal converter 14 contains a printed circuit board with electronic components. The signal converter 14 comprises an amplifier 15, a puls coupler 16, four bit-counters 17 and four latchers 18. As shown, the am¬ plifier 15 of the signal converter is connected to the sensor unit 12 at the wheel 8, and the signal converter 14 is also connected to a printer gate Lptl of a computer unit by means of a standard parallel printer cable 20.

In performing the invention, the measuring disc with the sensor unit is mounted on a non-driving wheel of the vehicle by means of the claws shown in Figs. 5 or 6. The sensor unit 12 is then connected to the sig¬ nal converter unit 14 which is connected to the cigar lighter of the ve¬ hicle. The printer cable 20 is then connected to the Lptl gate of the computer unit 22. Thereafter the weight of the vehicle, the transmission of the gear and the differential gear, the circumference of the wheels 8, the air temperature and the barometric height are recorded, and a test driving may be initiated.

According to the invention the test driving is preferably carried out by accelerating the vehicle from idle to top speed in the highest possible gear. Thereafter the vehicle is declutched and rolls until it has dece¬ lerated to the starting speed. During test driving the optocoupler 13 of the sensor unit 12 transmits light through the rays 2 of the measuring disc 10. By means of the reflector 26 the light is reflected and re¬ ceived by the optocoupler. By means of the computer unit 22 the number of pulses from the rotating measuring disc 10 is recorded in units of time of 1/10 sec. The units of time are taken from the clock of the com¬ puter unit 22. As the wheel 8 turns the pulses from each ray which is passed are sent to the signal converter 14. Firstly, the signal conver¬ ter 14 amplifies the pulses, and then the frequence is doubled in order to increase the accuracy. Thereafter the frequence is converted into a 16 bit number via a number of interconnected counters. For each 1/10 sec. the computer generates a puls which causes the 16 bit number to be divided into 4x4 bits, whereafter the four values may be transmitted via four latchers to the computer unit 22 through the parallel printer gate Lptl.

The fact that the driving method used for determining the power perfor- mance consists of an acceleration followed by a deceleration is an es¬ sential characteristic of the invention. The test may consist of one continuous drive or several combined drives, since separate tests may be made for acceleration and deceleration, respectively. It should be noted that the test may be made on any type of road, including roads which are level, or which climb or slope. Furthermore, the test driving may be made with all conceivable weights. In connection with the acceleration it should further be noted that it may start at all conceivable starting velocities and up to all conceivable velocities since the fact that the acceleration is made in a fixed gear is a special characteristic of the invention. Furthermore, the deceleration may be made either in a neutral gear or in gear, or in gear but declutched.

It should further be noted that data may be recorded by means of laser technique from the roadway or from a stationary station to the vehicle, or, alternatively, by means of ultra sound technique from the roadway (doubler technique) or from a fixed base to the vehicle. Alternatively, data may be recorded by means of an internal or external sensor from the wheels or the power or driving line of the car, or via the speedometer or speedograph of the car, via the ABS system or cardan sensors of the car, via the control electronics or the engine electronics of the car, via satellite navigation (GPS), or via radar, such as police equipment.

The storing of data may further take place via an accompanying PC, by means of the electronic U-pros of the vehicle, as a sound or another signal on a tape recorder, in the engine computer of the vehicle, via a data logger, or by means of a stationary or mobile station to which the data mentioned have been transmitted wirelessly.

The data processing may take place via a PC, a computer made for the purpose, manually transmitted data to a spreadsheet, mathematical per¬ ception, or by graphical perception.

Below, the practical use of an apparatus according to the invention will be explained more in detail in accordance with a user's manual concern¬ ing the said apparatus.

A traditional rolling road measures the power of an engine in the fol- lowing way:

The car is fixedly mounted on the rolling road with the driving wheels on rollers. The rollers may be contrailably braked so that the power of the car may be measured. Since the vehicle is stationary it is necessary to place a fan in front of the radiator of the vehicle in order to avoid superheating of the engine. The evident advantage of this measuring me¬ thod is that it is possible to adjust the engine and test it at the same time. The great disadvantage is that it is not possible to measure top speed, acceleration or braking ability due to lack of wind resistance and road friction.

The apparatus according to the invention measures top speed, accelera¬ tion, engine power and torque as well as possible speedometer variations and road friction and wind resistance. The measurements are carried out on road and therefore make allowance for - and measures - road friction and wind resistance. The measuring method is quick. A complete test only takes 15 to 25 minutes, including mounting.

The test may e.g. provide the following results:

- Acceleration shown as speed/time from 0 to top speed.

- Acceleration measured in distance, e.g. 0 to 1000 m.

- Intermediate acceleration in specific gears (e.g. k ph 80 to 130, ect.). - Power and torque on engine from idle to top rpm.

- Wind resistance and road- and gear friction due to velocity.

- Speedometer variations shown as chart or bar diagram.

Furthermore, the skilled operator can measure the braking distance and for instance analyse the performance of the vehicle over a predetermined length of road.

The tests are carried out as follows:

A disc with measuring points is mounted on a wheel of the vehicle. A sensor is mounted in the centre of the disc and connected through a light cable to a portable computer inside the car via a signal conver¬ ter. Before the car is started, some files (car makes) must be opened in the computer programme, whereafter the necessary specifications of the car are entered.

Acceleration (and possibly top speed) test:

- Start the pc. Choose a relevant file in the directory. - Accelerate the car from standing to the speed to which you wish to test the car. The test is completed.

This test gives you the acceleration in a diagram showing time in 1/10 sec, distances and speed, and in a table. It gives you the acceleration in each gear (and possibly the braking ability, in case of maximum bra¬ king without locking). The braking ability is shown (if measured) as a graph. Power test:

- Choose a new file from the directory.

- Select the gear you have chosen for the test and drive with the lowest possible rpm (idle, if desired).

- Start to collect the data and accelerate at the same time, as quickly as possible, without changing the gear, until you reach top rpm (red area on the rev. counter). - Push the clutch to the floor and let the car decelerate to a speed below the starting speed.

This test gives you a graph showing the acceleration from the initial speed to maximum speed, in the chosen gear, as well as the deceleration to just below the initial speed. This graph is processed by the computer which shows the result as two graphs, one showing h.p. (or kW), the o- ther Nm (torque). After processing the highest h.p. and Nm at the rele¬ vant rpm is shown on the main menue concerning the car make in question. The combined road and wind resistance at different speeds is shown as a separate graph.

The basis of the power test (Fig. 9):

The test graph is shown as a graph in which the vertical axis (x) is speed and the horizontal axis (y) is the time.

For each speed we now have two values: One during acceleration and the other during deceleration. The engine power is the sum of these two values.

During acceleration we have the following relevant forces:

The engine, which supplies energy.

Road friction, which consumes energy. Wind resistance. which consumes energy.

The graph of acceleration = engine power - road friction + gear friction + wind resistance.

The graph of deceleration = road friction + gear friction + wind resistance.

If we add these together, the result is the power of the engine measured at the flywheel.

If the road is purely straight or level and the wind speed is constant, the results of the tests are very accurate.

Even the friction of the transmission and the differential are taken in¬ to account. These resistances (plus the wind resistance and road fric¬ tion, which, of course, is the same during acceleration and decelera¬ tion) are included in the measurements, provided that you hold the clutch down during the deceleration and keep the gear engaged.

Speedometer check.

For this test you may use the same file as the one used for the power test.

Accelerate moderately. When the speedometer passes 10 kmph press FI, 20 kmph press F2, etc. 110 kmph press 1, 120 kmph press 2 etc.

When the test is completed, the result may be shown (and printed) as a table or a bar diagram.

All diagrams, graphs and tables can be printed out.

The Dvnomet equipment (Fig. 1).

The equipment (the hardware) consists of the following components: - A measuring disc fitted with a sensor unit, cable and plug for the "signal converter box".

- A signal converter box. - 5 claws with bolts and washers.

- 10 sleeves for 19 mm wheel bolts.

- 10 sleeves for 17 mm wheel bolts.

- A printer extension cable.

- A portable computer.

The Dvnomet program.

The program is installed onto the hard disc by means of the accompanying installation disk.

* Place the installation disk in drive a:.

* Run the program install.exe from a: Type: A: <Enter>

Install <Enter>

Choose "Adjust" if you want to adjust an existing programme. Choose "New" if you wamt tp install a new the program.

1. The programme creates a directory named DYNO ET" in which it places the actual programme and the help files.

2. The programme creates a directory named "DYNODAT" in which it stores the data from the tests.

Calibrating the system:

When you start the programme on your computer for the first time, the system will calibrate itself. The accuracy of the test to be made is completely dependent thereon. If you want to recalibrate at a later time, you must do so by starting the programme with the parameter k.

Type dynomet k <Enter>

This forces the system to recalibrate. The calibration is only possible with the system assembled.

This calibration enables the programme to use the clock of the computer for measuring time.

The computer has now created a file in the DYNOMET directory called: dy- nosys.ini, in which the "timer constant" is saved, so that no more cali¬ bration is needed, unless the programme is replaced, or you want to use a different computer from that used during calibration.

Mounting the measuring eouip ent: (Figs. 5 and 6)

Mount the measuring disc on a non-driving wheel, in order to avoid in¬ terference from wheel slip, etc., by means of the enclosed claws.

The claws fit 21 mm bolts/nuts. For bolts/nuts of 19 mm or 17 mm a sleeve is fitted under the claw. For 17 mm two sleeves (one large and one small) are fitted under the claw. Claws for 19 mm and/or 17 mm can be purchased as accessories.

* The claws are placed on the wheel bolts/nuts.

* The measuring disc is placed on the claws (it fits on wheels with 3, 4, or 5 bolts. If the wheel has 6 or 8 bolts very second bolt is u- sed). Mount the disc with the Allen screws. Tighten with a moment of 1.0 kg/m. Remember to place the washers beneath.

It is important to mount the disc accurately to obtain the best results.

* Place a wire (3.5 to 4.5 mm) in the hole of the sensor. * Fasten the wire in the sensor with the centre screw and tape the bracket on to the body of the vehicle.

The wire must protrude at least 10 cm above the racket because of the vertical movements of the wheel.

* Fasten the cable onto the wire with tape.

Take care that the cable forms a loop so that it is not damaged due to the movements of the wheel. Trail the cable into the car between the door and the door frame (or through a window).

* Connect the signal converter to the computer's Lptl port using the printer extension cable.

* Connect the power plug to the cigaret lighter plug of the vehicle.

Registering the data of the car.

* Turn the computer on.

You will now have the main menu on the screen.

* Press "b" (File name).

* Press "FI" and create two or more files for the test, e.g. "Carlacc" for an acceleration test, and "Carlpow" for a power test and speedometer check.

When creating files you will now be asked the following questions:

- <> The circumference of the non-driving wheel. - <> The circumference of the driving wheel.

- <> The total gear ratio. (Gear and differential)

Differential ratio Total weight. Air temperature. - Air pressure.

Description, e.g. name of customer, registration number of the vehicle, date of test, type of test, etc. max. 55 digits. <> Can be measured by the pc. Vide below

See the detailed explanation of the data to be registered on one of the following pages.

Recording the test data;

Acceleration test:

* You are stationary and ready to let the car perform its best.

* Choose the file "Carlacc" in the directory.

* Press "I" (collect data), the computer screen shows "ready" * Accelerate, as fast as possible, to the chosen speed.

At the instant the car moves, the measuring starts. During the driving part of the test, elapsed time and speed will be shown on a speedometer on the screen.

* When you have reached the desired speed (or distance) press "Esc' and the data has now been recorded.

Power test (Fig. 10):

For this test you must use a completely straight or level road. You have decided which gear you want to use. For the best result choose the high¬ est possible gear to let the engine produce the maximum output to reach max. revs. (3 gear of cars or 8 to 9 gear of trucks). This is the way to do the test:

* Choose the file "Carlpow" from the directory.

* Drive as close to idle as possible in the chosen gear. This speed determines the lower limit for the revs, that the graph will show.

* When you are ready press "I" and accelerate as fast as possible (do not change the gear).

* When the engine reaches its max. revs, (the red figures on the rev. counter), press the clutch down and let the car decelerate until the speed is below the initial speed. Do not put the gear in neutral du- ring the deceleration.

* When the speed is below the starting speed press "Esc".

That is the end of the test.

You can check that the test was satisfactory by pressing "a". This will bring the graph on to the screen.

Deleting test results:

You can use this facility if you want to re-use the file or if you are not happy with the test. Press "s" and all the collected data will be deleted. The specifications for the car will not be affected. If you perform another test in the same file without first deleting the data, the new test will overwrite the old one, but if the new test takes less time, you will end up with part of the old graph on the screen and that will interfere with the calculations.

The maximum time for a test is 400 seconds (6 in. 40 se ).

Speedometer check (Fig. 11):

With this facility you can check the speedometer for its variations. The invention provides a very accurate speedometer and you can press FI to F10 and the keys 1 to 6 to check the speedomenter. This is how it is done:

* Choose the file "Carlsp" (or Carlh.p.).

* Press "h" (Speed control). * Press "i" (Collect data) on the new display.

* Accelerate (or decelerate) moderately. When the speed shows:

10 kmph, press FI

20 kmph, press F2 30 kmph, press F3

etc. up to and including 100 kmph, thereafter:

110 kmph, press 1 120 kmph, press 2 130 kmph, press 3 etc.

The maximum speed which can be measured is 160 kmph.

Exit the collection by pressing "Esc".

Type "g" to show the results in a bar diagram. Return to main menu by pressing "Esc."

Calculating and analyzing the collected data:

You may now process/calculate/analyse the collected data:

If you have a pc with colour screen and a printer, it may be an advan¬ tage to load a copy of the programme into it.

The use of a mouse is advantageous. It may be used throughout the pro¬ gramme.

Printing the results (Fig 12).

Some results are printed by pressing "F6", others by pressing "Print screen", In order to set up printing you must run the file "graphic.com", which you find in the DOS directory. This enables you to print graphics on an ordinary matrix printer. The easy way is to add the command "graphic.com" to the autoexec.bat file in your main directory so the command is run automatically when you start your computer.

Acceleration test:

Choose the file, in the main menu (via the directory), which you used for the acceleration test. In this case "Carlacc". You have two ways of analyzing the result:

1. Acceleration shown in table.

* Press "V"

The data measured are now displayed in a table. The table shows the time from start, the distance driven and the speed. You can scroll through the table by using the arrows. The mouse is also active here. Place the cursor on top of the table. Press the mouse-button and the table scrolls backwards (the same ap¬ plies for downwards).

Printing the table: * Press "r"

Here you are asked for time from and to which you want values printed.

Example: * From sec? Type e.g. 8.0 * to sec? Type e.g. 9.0

The table will now be printed out from and to the demanded times with 1/10 sec. intervals.

Furthermore, you have a possibility of activating a trip counter which enables you to clear the distance from e.g. 5.0 sec. Press 1 and clear from xx sec. Acceleration shown as graph (Fig. 13):

The acceleration graph is displayed on the screen by pressing "A".

Thereby the acceleration of the vehicle is displayed graphically.

By means of the mouse you can adjust the x and the y axis. Place the mouse cursor on min. or max. and use the left or the right mouse-button for adjustment. If you do not have a mouse, you can also use the arrows, home, end, pgup, pgdn, h, k, n, m, as indicated on the screen.

When you have adjusted the axis press "Enter". If you press "F2", a "raw" graph - possibly with electronic interference and other odd

"jumps". Pressing "F2" again will clean up the graph and leave a neater appearance.

G-forces:

By pressing F7 yet another graph will appear showing the G-forces en¬ countered during the test.

To Print: Press "F6".

See under Colour setup if you want to export a "bmp" file instead.

Power test (Fig. 14).

Nm and Hk:

* Choose the appropriate file in the main menu, (carlpow). * Press "A" (Data shown as Graph).

* Press "F3" to process this graph into h.p. and Nm. (This presupposes that the test was made in accordance with certain conditions. If the deceleration graph (of the collect graph) does not go as far down as the starting speed (e.g. due to prematurely interrupted deceleration) you may limit the calculation area by placing the cursor, by means of the mouse, on the last usable part of the collect graph before start¬ ing the calculation (This is then started by pressing Shift+F3).

The computer manipulates the graph and processes it. The indicator on top of the screen shows how far it has come. This takes a few seconds. The screen changes to show two graphs (h.p. and Nm).

The h.p. graph can be shown as kW by pressing "space", or by placing the mouse cursor on h.p. or kW in the upper left hand corner and pressing the mouse button.

If you press "F2" h.p. (kW) and Nm at the wheel will be shown. Pressing "F2" again will remove the graph.

On the left you see the scale for power (h.p. or kW). On the right you see the scale for torque (Nm). At the bottom there is a scale showing revs./min. The values may be changed by pressing the right or left mouse button when the cursor is at the value to be changed (min or max) - which is then marked with green. Or you may adjust the "picture" by means of the keys indicated on the screen. After adjustment press Enter.

Adjust the graph to fit the screen.

If you put the mouse cursor on the graph you will see the position (ef¬ fect and revs.) in the top left corner of the screen.

To print: Press "F6".

If you press "Esc" you will find max. power and max. Nm against revs . indicated on the main menu.

Double graphs (Fig. 15):

Just as you can choose from different tests already recorded in the di¬ rectories, you can choose a second test for comparison. The second test is chosen by pressing "L" from the main menu.

This allows you to compare two graphs (e.g. before and after an adjust¬ ment). You may also calculate the average of two test in order to obtain the highest degree of accuracy.

Average (Fig. 16):

If you have a test graph with two tests (Power test (Fig. 14)) the pro¬ gramme can also provide a graph showing the average of the two by press¬ ing "F5". Type a new file name for the file containing the average. Thereafter, the average graph is displayed.

Road/gear friction and wind resistance (Fig.i7):

* Choose the file "Carlpow".

* Press "M".

A graph will now appear showing the energy the car needs to maintain a certain speed. The graph is calculated from the efficiency test.

You can choose to collect the data in a separate test in a separate file. If desired, make a test run, in which you bring the car to its top speed, even if you have to change gear. Having reached the desired speed, press down the clutch and let the car decelerate to a suitable low speed before stopping the test.

Process the graph by pressing "F3". You can now see the energy consump¬ tion compared to the speed. Theoretically the wind resistance increases with the square of the acceleration.

If for example 100 kmph demands 15 kW., then 200 kmph should demand 120 kW ((200/100)³*15), 300 kmph should demand 405 kW, etc.

Since the road and gear resistances are included, it is not possible to calculate the theoretical top speed accurately, but the graph shows you exactly how much the combined road/gear/wind resistance is affecting the car.

This facility can be very useful to employ before and after having in- stalled accessories such as a spoiler to document its effect on the fuel economy or lack of such effect.

Here two graphs may also be displayed in the same graph.

Speedometer check.

* Choose the file "Carlpow".

Files (cars) in which you have collected the data for the speedometer check are marked with an * before "H" in the main menu.

* Press "H".

* Press "r" to print a list with speedometer variations.

The variations can also be shown as a bar diagram (Fig. 18).

* Press "g".

* Press "Print screen" to print the diagram.

Detailed explanations:

Creating a file:

From the main menu you choose "File name" by pressing "B" or place the mouse cursor on "B" and press the left button.

A list of file names of cars appears on the screen. To create a new file (for a new test) , press "FI". Now write a unique name of no more than 8 digits and press "Enter".

You will now be asked for the following:

(If during this process you just press "Enter" without entering new values, you will copy the values of the data field of the main menu.)

Measuring wheel :

Method 1:

The specification needed is the circumference, in cm, of the wheel. The easiest way to measure the circumference of the wheel is to place the car on a flat, hard surface, put a chalk mark on the asphalt and a corresponding chalk mark on the wheel. Then move the car until the wheel has made 10 revolutions. Mark the asphalt again. You can now measure the distance between the two marks and divide the result by 10. Type the re¬ sult and press "Enter".

Method 2:

For this method it is necessary to have the facility of a marked stretch of road measuring exactly 1000 metres. (If possible, check it yourself).

Start the computer and make ready for measuring, take the car to the marked stretch of road.

Place the car at the zero mark and press "k".

Drive to the 1000 m mark at normal driving speed.

Press any key. The computer will now calculate the wheel circumference.

This method is very accurate since it measures the "dynamic" circum¬ ference thus taking the deformation of the tire into account. The method is by far the fastest too (as soon as the stretch has been marked).

Driving wheel :

As for the measuring wheel, to be entered in cm. Here Method 2 is not applicable, but if the size is the same as the non-driving wheel just enter the same figure again. Gear Ratio:

Here the rear-axle assembly is meant. It might for instance be 3.36 (use . when entering).

NOTE: To find the ratio, multiply the differential ratio with the ratio of the gear you intend to use during the efficiency test. If for in¬ stance you intend to perform the test in 3rd gear (not all cars keep within legal speed in the 4th gear) which has a ratio of, let us say, 1:1.3 and the ratio of the differential is 1:3.36, you multiply 1.3 with 3.36 and get the result: 4.368. Enter the calculated value here.

If you cannot find the ratio of the car to be tested, you can use the programme to calculate it.

In the main menu you choose the item speed control, and thereafter col¬ lect. The drive at exactly 3000 rpm in the desired gear (1000 rpm for trucks). When you drive at exactly 3000 rpm you press 7. Thereafter the total gear ratio is calculated. The value calculated is transferred to the data of the car. Differential ratio: you will have to look in the owners manual; if no value is stated, use the value 4.0.

Weight:

Write the total weight of the vehicle including yourself, the petrol and anything else in it. Weigh the car (and everything in it) on a scale, if the test demands a high degree of accuracy. Otherwise, take the weight stated for the car, add your weight (and that of a possible passenger), add the weight of fuel and oil, etc. Of course the weight is important, but if you want to measure efficiency, before and after an adjustment/- repair, the weight is less important, as long as it is the same at both tests.

Air temperature:

Write the air temperature in Celcius at the time of the test. A couple of degrees more or less is not important.

Air pressure:

If do not have a barometer, enter the standard value which is 1013 millibars.

Changing the specifications of the car.

When you have chosen a car (file) in the directory, you will see the specifications on the screen. If you wish to change any of these specifications you press the highlighted letter in front of the item.

Then write the new figure and press "Enter". Example: the weight of the car, when weighing it, turns out to be 1200 kg. instead of the calculated 1175.

Press "c" whereafter the computer asks you to type the new weight. Press

"Enter" when it is done.

Files in general

All the files used for recording test data and car specifications are stored in the directory. With "buffer" and "files" adjusted to 30 in the config.sys you have room for 60 files (cars). Be sure to delete files not needed and it may be a good idea to transfer records you wish to keep, to floppy disks.

The above mentioned records stored in the DYNODAT directory are divided into three files per car:

*.acc holds the records from the tests.

*.nm is used for the processing of the data to h.p. and Nm graphs. *.ttt holds the description line.

Directories:

If from the beginning you sort your files (car tests) into directories, it will make it simpler to find the files (tests) later.

You find the list of directories by pressing "B". You can create as many directories as you like but a suggestion is to create a directory for each make of car.

Example: you want to test a Fiat Tipo.

* Press "B" to open the directory.

You can see which directory you are in at the moment, beneath "file name" in the main menu.

If it says "C:\DYN0DAT\, you are at the "base" of the directory and you press ">" (Change directory).

A list of directories created appears (on the right).

If you have a directory called Fiat, highlight it and press "Enter". Under "File name" you will see that C:\DYNOMET\FIAT\ has appeared. Press "<" and the highlight changes to the left side and a list of tests with all Fiat cars tested appears.

If you do not have a directory called Fiat you can create one: Press "FI" to create a directory, Write "FIAT" and Press "Enter". Press "<" and create a file as explained earlier.

Always note what it says beneath "File name". Otherwise you may easily "loose your way" in a directory.

Transfer of files:

If you want to move a file (test) to another computer you can do it in the following way:

Copying to diskette:

Insert a formatted diskette into the disk drive. Enter directory "b".

Choose the file to be moved by highlighting it. Press "F4" . The file will now be copied to the diskette.

Copying from a diskette:

Insert the diskette into the disk drive. Enter directory "b"

Choose the directory to which the file is to be moved. Press "F5". Choose the file to be moved and press "Enter". The file will now be copied.

Colour setup:

You can customize the colour setup by pressing "F" in the main menu. From here you can adjust: Colour of text, Code letter, "Dark" text colour, Nm colour, h.p. colour, Cw colour and colour of the graphic background etc.

Further more, you can choose from the following:

Box on Lptl or Lpt2:

Normally Lptl ; but some laptop computers have an integrated printer using the Lptl port; in that case you must choose the Lpt2 port.

0=Demo, l=Always, 2=Auto. 2=Auto

Normally the setting will be 2 (Automatic). Most computers will detect if the signal converter box is connected or not. If the signal converter is not connected, the programme will change to Demo mode.

l=Alwa s.

This setting is used if the computer itself cannot detect whether the signal converter box is connected or not.

The programme will attempt to communicate with the signal converter, in failing connecting the programme will halt if the system is not as- sembled.

0=Demo

The programme is transformed to a demonstration version. If you press

"I" to collect data the speedometer will just move back and forth.

0/print 1/exp sh 2/exp

0: Using an ordinary matrix printer. 1: File export in black and white.

If you have chosen 1 (file export), the programme will create a "bmp" file when you press "F6", this file will be placed in C/DYNODAT directory and named with successive numbers.

2: File export in colours.

As above, but in colours.

Smoothing:

With this facility you can decide how smooth your curves are going to be presented. If you "smooth" too much, accuracy will suffer; too little will leave a jacked curve. Recommended value: 4.

Filter:

A filter also available under the colour menu may be used for instance for filtering away electronic interference. The filter can be set at 10 different degrees (from 0% to 100%). The filter often assist in smooth¬ ing a bad curve. However, sometimes it is better not to use it. Try it! Often it can spare you a new test.

Normal value: 0

NB: As with most forms of filtering, it is often better to drop it.

Calculator:

The system has an integrated calculator, which you activate by pressing "g". You can operate it both by means of the keys and with the mouse. If for instance you use the calculator to calculate the gearing/differen- tial ratio, you can transfer the result by pressing "F10".

Maintenance:

After some time in use, the sensor wheel may need disassembling, clean¬ ing, and lubricating. The symptoms are difficulties in making a smooth measurement without interference. You disassemble the sensor wheel which consists of the following com¬ ponents (starting from the back):

1 self locking nut with disc.

1 reflector disc. 1 measuring disc.

1 spacer.

1 washer.

1 sensor unit with sensor.

1 6 x 35 mm Allen screw

Clean the components with emphasis on the optocopler (photocell) and the slots in the disc

Impregnate the washer with ordinary oil.

Assemble the unit exactly as it was before.

Notes concerning tests with the apparatus according to the invention:

Cars .

When testing an ordinary car, you should use the highest gear in which the engine can accelerate from idle to top revs. To obtain the best result, the acceleration should take between 10 and 30 seconds, but of course no definite limits can be set up.

I.e. even if the car can reach top revs, in fourth gear, it will not produce a good result if it takes 60 seconds to reach that speed. The curves will be accurate enough but will be very uneven.

On the other hand, if the car is so powerful that the acceleration only takes for instance 7 seconds, the acceleration graph will be siery straight and very theoretical. There is also a risk (if the engine is turbo charged) that the turbo charger has not buildt up full pressure because the engine has not been fully loaded. This will result in a graph showing too little effect.

The problem is not so great for ordinary cars. You may have a car which is so powerful that you drive more than intended in the selected gear, but that is not very important. The problem is greater when measuring commercial vehicles.

Commercial vehicles (trucks).

The engines in commercial vehicles are a lot more powerful than the en¬ gines of cars. Their engines are designed to work hard and because of the large volume the range of revs is very narrow, typically between 1100 and 1900 rpm. The turbo charger does not normally work at revs, less than 1000 rpm, and many engines cut off the fuel supply at around 2000 rpm.

The driver often has an unsynchronized fullerton gear box, with 17-18 gears, at his disposal. He will soon find a suitable gear for a given load, speed and climb. Because of varying weight compared to the power of the engine, it may sometimes be difficult to decide the right gear and weight for a test. A tractor unit is virtually impossible to measure without a trailer. However if the tractor is not fitted with automatic shut down of the pump at 90 kmph, a test may be possible in the highest or next highest gear. The best test is performed pulling an empty trailer.

It is not difficult to find a suitable gear if the truck is heavily loaded. The problem is to find a straight road long enough. A lorry weighting 40 tons and driving at 90 kmph takes a long time to slow down. Such a heavy vehicle also demands a very level road, since even a small hump on the road will affect the final result.

As a rule it is recommended to measure on an empty lorry (tractor unit and trailer) weighing 10 to 15 tons. Using the second highest gear will probably mean the top speed will be 70-80 kmph and the duration of the test will be 100 - 120 seconds of which the acceleration will take ap¬ proximately 20 seconds.

The acceleration time for a lorry should be between 15 and 30 seconds and brings the vehicle to a relatively high speed.

This method is very suitable for vehicles of 500 h.p.

If the power exceeds 500 h.p., more weight should be applied or the speed restrictor disconnected during one of the tests.

Toggle between car mode and truck mode:

* Leave the programme by pressing "Esc". * Write: cd\dynomet.

* Write: install.

* Highlight Adjust

* Highlight car or truck * Press "Enter"

* Highlight language

* Press "Enter"

* Highlight logo * Press "Enter"

The programme will hereafter start up in the last chosen mode.

Claims

1. A method of measuring the power or torque of a vehicle, CHARACTE- RIZED in that the velocity or speed of the vehicle while driving on a road and accelerating in a certain gear is recorded at certain time intervals or time increments, that, on the basis of the velocities recorded during acceleration, the change during the said time interval or time increment in the kinetic energy of the vehicle during acceleration is determined, whereafter the change in power during acceleration in the said time interval or time increment is determined, that the velocity of the vehicle while driving on a road and de¬ celerating in the same gear as when accelerating, or possibly de- clutched, is recorded at certain time intervals or time increments, that, on the basis of the velocities recorded during deceleration, the change in the kinetic energy of the vehicle during deceleration in the said time interval or time increment is determined, whereafter the change in power during deceleration in the said time interval or time increment is determined, and that a measure of power representing the power of the vehicle with¬ out loss in the transmission of the vehicle is provided by subtracting the change in power during deceleration from the change in power during acceleration, and subsequently converting the measure of power into a measure of torque.

2. The method according to claim 1, CHARACTERIZED in that driving during acceleration and deceleration is performed on the same length of road.

3. The method according to claim 1 or 2, CHARACTERIZED in that the time interval or time increment during acceleration is identical to the time interval or time increment during deceleration.

4. The method according to any of the claims 1 to 3, CHARACTERIZED in that in addition the number of revolutions or speed of the vehicle en¬ gine is recorded and that the measure of power is recorded as a function of the actual number of revolutions of the vehicle engine.

5. The method according to any of the claims 1 to 4, CHARACTERIZED in that the measure of power or the measure of torque is recorded as a function of the speed of the engine of the vehicle and that the power graph or the torque graph of the vehicle engine is printed out by means of a printer, a plotter, or the like.

6. The method according to any of the claims 1 to 5, CHARACTERIZED in that the velocity of the vehicle during acceleration and/or deceleration is recorded by means of a measuring disc and associated puulse detectors mounted on a non-driving wheel of the vehicle, by means of a laser mounted on the vehicle, by means of a laser mounted on the roadway, by means of an ultrasonic detector mounted on the vehicle, by means of an ultrasonic detector mounted on the roadway, by means of the internal velocity generating means of the vehicle, a speedometer or a speedo- graph, by means of a detector in the vehicle connected to an antilocking brake system or a traction or friction system of the vehicle (ABS or traction control) by means of a detector of the engine electronics of the vehicle engine, by means of satellite navigation equipment (par¬ ticularly GPS, Global Positioning System), by means of radar equipment, or any other velocity recording equipment.

7. The method according to any of the claims 1 to 6, CHARACTERIZED in that the recordal of the velocities of the vehicle during acceleration, and the calculations of the change in power during acceleration and de- celeration, as well as the subtraction of the change in power during de¬ celeration from the change in power during acceleration, and the conver¬ sion into a measure of power, and the possible additional coversion of the measure of power into a measure of torque, are performed by a com¬ puter, particularly a personal computer such as a portable personal com- puter.

8. An apparatus for measuring the power or torque of a vehicle, CHARAC¬ TERIZED in that it comprises: recording means for recording the velocity or speed of the vehicle at certain time intervals or time increments while the vehicle is driving on a road and accelerating in a certain gear, and, correspondingly, for recording the velocity of the vehicle while driving on a road and decelerating in the same gear as when acce¬ lerating, or possibly declutched, at certain time intervals or time in- crements, calculating means which determines, on the basis of the velo¬ cities recorded during acceleration, the change during the said time in¬ terval or time increment in the kinetic energy of the vehicle during ac¬ celeration, and thereafter determines the change in power during accele- ration in the said time interval or time increment, and, corresponding¬ ly, determines the change in the kinetic energy of the vehicle during deceleration in the said time interval or time increment, and thereafter determines the change in power during deceleration in the said time in¬ terval or time increment, and subtracts the change in power during de- celeration from the change in power during acceleration thus providing a measure of power representing the power of the vehicle without loss in the transmission of the vehicle, and optionally converts the measure of power into a measure of torque.

9. The apparatus according to claim 8, CHARACTERIZED in that the calcu¬ lating means is a computer, particularly a personal computer.