SU1573355A1 - Method of determining mechanical efficiency of i.c. engine - Google Patents

Abstract

The invention relates to engine construction and is intended to determine the mechanical efficiency of an internal combustion engine. In order to simplify and improve the accuracy and performance of the engine, the position of the fuel control is fixed and the P cycles with combustion out of the total number M are shut off. The steady speed is measured. Based on the P / M ratio of the number of cycles shut off with combustion to the total number of cycles, the numerical value of the mechanical efficiency of the engine operating at a measured steady-state rotational speed with all cycles enabled with combustion at a fixed position of the fuel control unit is determined. 1 il.

Description

(Ls

The invention relates to mechanical engineering, in particular engine building, and is intended to determine the mechanical efficiency (EFF) of an internal combustion engine.

The purpose of the invention is to simplify and improve the accuracy and performance of the method.

The drawing is a diagram illustrating the proposed method.

At an arbitrary initial frequency of rotation of the engine idling (point J, in which the mechanical efficiency is zero), P cycles are disconnected with burning out of the total number of cycles m at a fixed position of the fuel control. The frequency of rotation will change (point 2, see diagram).

At steady speed, the engine speed is measured. In this case, the mechanical efficiency of the engine, which operates with the disconnection of the P cycles with combustion at a fixed position of the fuel control control, is also cool (point 2),

The mechanical efficiency of the engine at the steady-state (in this case, measured and) rotational speed during its operation with all the cycles turned on, with combustion at a fixed position of the fuel control control element is

cl

00 00

ate

n -I-.

LM N;

(ABOUT

where N, N - - respectively conditional

mechanical loss power and engine power indicator.

It is known that when the engine is idling, all the indicator power developed by it is spent on mechanical losses. When the engine is idling with P cycles disabled with a total of m cycles (switched on and off) out of the total number of m cycles, its indicator power is T-P

N.

one

N.

(2)

m 1 where (tp) - the number of cycles included

with combustion.

Assuming that the conditional mechanical losses at the steady-state engine speed with the cycles off and on with combustion are equal (due to the thermal inertia of the coupled parts, working conditions close to those with constant fuel supply to the cylinder are maintained)

(3)

N N m on motkl

or n. - N ..

M m 1

Solving equations (1) and (3) is semi

H ± and

m-P P.

LM

one

w n r t

 1t

t

Therefore, at the measured steady-state rotational speed (point 2)

. R

attitude is mechanical

Efficiency of the engine operating with all the included cycles with combustion at a fixed position of the fuel control control unit (point 3). In practice, it is advisable to ask

an attitude

- in the range of pre-m

the desired change in the mechanical efficiency of the engine at a given position of the fuel supply control unit.

The method allows to reduce the test time, since only the steady-state rotational frequency is measured. It is simple to implement, does not require the establishment of a predetermined engine rotational frequency before each measurement and therefore is more productive.

By turning off the cycles with combustion in separate cylinders, the thermal tension of all cylinders is alternately maintained.

0

c

Q

five

0

five

0

the absence of sudden changes in temperature of parts of the cylinder-piston group when switching on and off cycles with combustion, which brings the engine to real conditions, reducing the error in determining the mechanical efficiency.

Example. Let a four-cylinder engine, with an arbitrary initial position of the fuel control body, has an initial part. The amount of idle rotation rpm (point 1). This rotational speed is not measured, but for sleep we assume that rpm. After disconnecting P cycles with combustion at a given ratio P / t equal to, for example, 7/10, the engine reduces the rotational speed and, at a fixed position of the fuel control body, its steady state idling speed is 1500 rpm. This means that with a rotational speed of rpm (point 3) and a fixed position of the fuel control unit, the mechanical efficiency of the engine is 0.7, which is confirmed as follows.

At the measured rotational speed, rpm, at a fixed position of the fuel control unit, and from every 10 cycles, 7 cycles are disconnected periodically and (T-P) 3 cycles with combustion are periodically performed in cylinders.

Consequently, at the measured rotational speed of idling at a fixed position of the fuel control and the indicator power of the engine is equal to

)and;

and the floor is consumed (tP)

for mechanical losses, i.e.

N .. 3/10.

Mm3

At the same frequency of rotation n3 1500 rpm with all working cylinders, i.e. when the engine is operating without shutting down the cycles with combustion and the fixed position of the fuel control body, its indicator power will be N j, and the conventional power of mechanical losses will remain the same, i.e. N 3/10-N-, since the rotational speed does not change and is equal to rpm. Then the engine will develop some effect.

tive power. -NM N - 3/10 N. 7/10 N; and its mechanical K1SC will be equal

1 / and

Ne 7/10

n5 iЈtf N; N; 0 ,.

or

m

,

.i-gg-i- 1-3 / 10

0.7- -. t

In the considered example, the mechanical efficiency, 7, the engine has 1500 rpm at a measured rotation frequency and with the frequency developed at this frequency without shutting down cycles with burning effective power, corresponding to a fixed, position of the fuel control unit.

Compiled by V. Gorbunov

Editor S. Patrusheva Tehred M. Didyk

Order 1638 Circulation 473 Subscription

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 1/3035

73355 .6.

Claims (1)

Invention Formula The method for determining the mechanical efficiency of an internal combustion engine is to periodically turn off the cylinders for a certain number of cycles at certain, pre-selected time intervals: either during engineless engine tests. 10 bodies in idle mode, rotational speeds are measured and, based on the measurement results, the efficiency is measured, in order to simplify the process of determining, increasing 15 accuracy and performance, the cylinders are shut off at a fixed position of the fuel control control unit, the steady-state rotation frequency of the engine is measured, and the magnitude of 2o the efficiency of the engine operating at the measured steady-state frequency with all the cylinders turned on is judged by the ratio of the number of cycles, with the cylinders off to the total 25 number of cycles in all cylinders. Corrector 0. Ciple