RU1814043C - Rig for testing internal combustion engine - Google Patents

Abstract

SUMMARY OF THE INVENTION: A test bench consists of a load-bearing DC electric machine connected to a test engine. A rotary EMF meter is connected to the terminal clamps of the machine, which consists of a voltage divider across resistors and a normalizing amplifier. The output of the amplifier is connected to the input of an analog-to-digital converter, the output of which is connected to the input of the computer, which consists of random access memory, logical switching device, read-only memory. A pulse-type speed sensor is connected to the input of the frequency converter into a code, the output of which is connected to one of the inputs of the logic switching device. The core current meter is connected to the ADC input, the output of the latter is connected to a moment computer connected to the display, which consists of a keyboard and a screen. The output of the calculator is connected to the input of the digital-to-analog converter, and its output is connected to one of the inputs of the comparison device, to the other input of which a field current meter is connected. The output of the comparator is connected to the input of the voltage regulator. 4 silt, WITH

Description

The invention relates to methods for testing internal combustion engines (ICE). primarily automated test bench systems.

The purpose of the invention is to increase the efficiency of ICE testing by improving the accuracy of measuring torque and the quality of loading conditions.

The implementation of the test bench with marked distinguishing features allows one to take into account the effect of changes in the voltage drop across the windings of the load electric machine and the voltage drop on the brush contacts, as well as steel losses and additional losses, which provides more reliable initial information about the loading mode. Processing this information in

digital form provides the necessary accuracy.

In FIG. 1 is a functional diagram of a test bench for an internal combustion engine; in FIG. 2 is a block diagram of a torque calculation program by an indirect method, by a microprocessor computing device; in FIG. 3 is a block diagram of a loss calculation program; in FIG. 4 is a design diagram for determining the emf of rotation.

The stand consists of a load electric DC machine 1 (for example, 4P series) connected to the motor under test 2. A rotary EMF meter 3 is connected to the main clamps of the machine, which consists of a voltage divider on resistors 4, 5 and norm00

6.

5. with

amplifying amplifier 6. The divider resistors have the same temperature coefficient of resistance as the windings of an electric machine.

As a normalizing amplifier, a U846NP / 2 standardizing converter can be used, which provides voltage conversion and galvanic isolation of power and measuring circuits.The output of the normalizing amplifier is connected to the input of an analog-to-digital converter (ADC) 7 (for example, type K752PV1), the output of which is connected from the inputs of the computer 8, consisting of random access memory 9 (for example, КР565РУ5), a microprocessor 10 (for example, К 1810ВМ86), a logical switching device 11 (for example, КР1810ВГ88), shedding device 12 (for example, K573RF2). The speed sensor 13 of a pulse type (see Chernyshev V. A., Safronov A. V. Sensors of the automation system in electric transport. - M., 1989) is connected to the input of the frequency converter in code 14, the output of which is connected to one of the inputs of the logic the switching device 11. The current meter core 15 (made, for example, using the E827NP12 converter) is connected to the input of the ADC 16, the output of the latter is connected to the computer 8, connected to the display 17, which consists of a keyboard 18 and a screen 19. Output torque calculator 8 n to the input of digital-to-analog converters 20 (for example, DAC type K 572PA), and its output is connected to one of the inputs of the device 21 comparison (for example, type KFU-0190; see Complete thyristor drives: Reference. - M.: Energoizdat , 1988), to the other input of which an excitation current meter 22 is connected, made, for example, on shunts with a standardizing transducer of the type E827NP / 2. The output of the comparator is connected to the input of the voltage regulator 23 (for example, a thyristor regulator of the PBT type), the output of the latter is connected to the excitation winding of an electric DC load machine.

The stand works as follows. Before starting operation, it is necessary to determine the following characteristics of a load electric machine in a motor mode in a known manner, see Kovarsky E. M .. Yanko Yu. I. Tests of electric machines. - M .: Energoatomizdat, 1988):

- voltage drop across the brush contact as a function of the load current (1);

- EMF of rotation as a function of idle speed n at two fixed values of excitation current (n) (n);

is the no-load current as a function of speed for two values of the drive current (n), I20 f (n).

The obtained characteristics are then input into the read-only memory 12 of the calculator, where the torque (in the form of a code) is calculated from the mechanical power P on the shaft of the electric machine and the rotational speed p:

Mk - -

0)

P (about 2 p

The calculation sequence of Mk is explained by the block diagram of the program shown in FIG. 2.

The mechanical power in the generator mode of the electric loading machine is defined as the sum of the electric power Pe and the power loss AP:

 AR. (2)

When calculating, they use electromagnetic power

, (3) where E is the emf of rotation of the electric machine;

I is the load current of the electric machine.

The EMF of rotation of an electric DC machine is determined in accordance with an equivalent circuit (Fig. 4), where indicated

Ri, Ra, respectively, the resistance of the compensation winding of the auxiliary poles;

Re - winding resistance core.

For a balanced bridge we have:

(Re + Ri) (4)

(5)

R2 + R + R2 lE + VuJ Ci (E + VuO -, .t (6) W Ci- Re + R% R2 Thus,) Vl2-Vu, (7)

Losses in an electric machine can be represented as:

А Р ДРтр хх + A PFe хх + А Рдоб., (8)

where DRtr xx - mechanical friction losses at idle;

ARre xx - losses got up at idle;

ARdob. - additional losses. Additional losses are independent of the rotation frequency and are calculated by the formula

Hvl2

(see Kovarsky E, M., I and co 10. I. Tests of electrical machines - M .: Energoatomizdat, 1990):

ARdob SiRn (t

G, (9)

 NOM

where, 005;

RN - rated power of an electric machine.

The remaining components of the losses DR LRTP xx + LRre xx depend on the speed

AR D РТр хх + А РШСТ + А Рвихр, (Ю)

where ARGist - hysteresis losses;

 And the eddy of eddy current loss, moreover

ARGist. В2п (11)

AR vortex "В2п2, (12) where В - induction in the air gap of an electric machine.

Friction losses are obtained from the initially detected characteristics for two values of the excitation current:

(n); (n): (n); (n):

Re xx1 Arth

rKC2 +) Ei2

Rekhkh2 DRtr + (C2 +) E22 It follows:

03) (I)

L оРехх2Е12-РЭХх1 E22

Ј GTR XX- ----------- o

Tr XX

E12-E22

h (REHX1 RE

 ---- 2 -

2

(15) (16)

and (pC2 + C3)

E1 / - Ј2

where Cg, Cc are the constants of the characteristics: Re ho:

Re l20.

The sequence of calculation of losses in the electric machine A P is shown in FIG. 3.

As noted above, after the initial characteristics of the electric load machine have been identified, they are entered through the display 17 using the keyboard 18. The input information is displayed on the screen of the display 19. Next, the test mode of the motor 2 is set using the same keyboard. The set value of the excitation current from the output of the calculator 8 ( in the form of a code) enters through the digital-to-analog converter 20 to the first input of the comparison device 21, the output of which controls the voltage regulator 23. A difference signal is generated in the comparison device 21 - p connectivity between the drive current setpoint and actual

0

10

fifteen

5

0

5

0

5

0

5

by the value determined by the excitation current meter 22, the Calculator 8 maintains a predetermined mode taking into account the current values of the rotational speed n supplied to its input from the sensor 13 via the frequency-to-code converter 14 and the ZDS rotation sensor 3 supplied through the anslo-digital converter 7.

The values of torque Mk and speed n calculated in block 8 are displayed on screen 19 of display 17.

Claims (1)

Thus, the proposed stand takes into account the voltage drop across the brush contacts and steel losses due to hysteresis and eddy currents. In this way, the accuracy of the torque measurement and the stability of the maintenance of loading conditions, i.e., the test efficiency, are improved. . The claims A test bench for an internal combustion engine, comprising a DC load electric machine, a core current meter of an electric machine, a rotational speed sensor coupled to an electric machine rotor, an excitation current regulator, an excitation current meter, a comparison device, a rotational emf meter and a calculator. The fact is that, in order to increase the efficiency of tests by improving the accuracy of measuring torque and the quality of loading conditions, two analogs are additionally introduced into it a digital-to-digital converter, a frequency-to-code converter, a display, a digital-to-analog converter, and the calculator is equipped with a random access memory unit, while a display is connected to the inputs of the calculator through analog-to-digital converters-current measuring devices of the core of an electric machine and emf of rotation, through a converter frequency to code is a speed sensor, the output of the computer is connected via a digital-to-analog converter to the first input of the comparison device, the second input of which is connected to the excitation current meter, and the output to the regulator of the excitation current, the rotation EMF meter is made in the form of a series-connected voltage divider, the inputs of which are the inputs of the meter, and a normalizing amplifier, one input of which is connected to the terminal of the electric machine, and the other to the midpoint of the divider. .Input passport persons, the same value T, b / I tanovf g - - , -vw "-" amachenh ul, G Ia  in characteristics (/ -Ј / ha, .Ы .Input passport persons, the same value T, b / I tanovf g - - fi fr V, -vw "-" amachenh ul, G Ia  g / s / t in the characteristics (/ -Ј / ha, .Ы    - - - / JV (END L Ig. 2. I ---- -I & stHeECTromagnet I machine