И инновации современной

44 
of vehicles is equal to 40 km/h. In [11] as a result of the analysis of 
vehicle's movement along the urban route, it was found that the most 
probable braking start speed is equal to 40 km/h. 
From the analysis of Figure 6 shows that it is reasonable to 
start braking with the engine at 40 km/h in the second gear with the 
deceleration of 1.5 m/s
2
, and finish at the speed of about 20 km/h 
with the deceleration of 0.9 m/s
2
. Since the car's deceleration 
characteristic at III gear in the section of speed change from 40 to 20 
km/h is almost linear, we can conditionally consider the car's 
deceleration as equidistant, with deceleration: 
0, 5
R
B
F
a
a
a
(8) 
where
B
a
and 
F
a
deceleration at initial and final speeds 
respectively.
The average deceleration will be 
R
a
= 1.2 m/s
2
, which is 
much lower than the recommended values. The way vehicle has 
traveled in the process of braking by the engine at a speed reduction 
from 
V
= 40 km/h to 
V
= 20 km/h, considering that it moves with 
a constant average deacceleration, let us define by the formula: 
2
2
2
y
R
V
V
S
a
(9) 
The calculation showed that the braking distance will be 64 m. 
After braking by the engine, the driver should reduce the speed to 
zero by the service brake system. We will determine the braking 
distance at speed reduction from 
V
to zero by the formula: 
2
2
stop
R
V
S
a
(10) 
At an average deceleration of 1.2 m/s
2
the brake path 
stop
S
= 

45 
12.6 m. Then the total braking distance of the car to a stop is 76.6 m. 
Such a large braking distance cannot always be realized in the city, 
so such service braking cannot be considered effective. 
In Figure 7 shows the dependence of the car's braking path on 
deceleration when braking with the engine from the initial speed of 
40 km/h. Line 1 corresponds to braking only the combustion engine 
with speed reduction from 40 to 20 km/h, and line 2 corresponds to 
braking ICE with speed reduction to 20 km/h with further speed 
reduction with the same deceleration until the car stops completely 
using the service brake system. 
Analysis of Figure 7 shows that in order to obtain an 
acceptable braking path when braking an internal combustion engine 
to a full stop at 40 km/h at a speed of 45-40 m, an average 
deceleration within 2.2-2.5 m/s
2
must be provided. The same 
established decelerations are recommended by GOST for the car 
spare braking system (Table 4). If this level of deceleration is 
provided and its smooth regulation is ensured, the internal 
combustion engine can be referred to the car's spare brake system. 
 
Figure 7 – Dependence of the car's braking path on the average 
deceleration: 1 – when braking only ICE with speed reduction from 
40 to 20 km/h; 2 – when braking ICE to 20 km/h and further braking 
to a full stop using 

46 
In Figure 8 shows the dependencies of the braking path on 
vehicle’s speed during braking by the service braking system with 
the initial speed of 40 km/h during emergency and service braking. 
Analysis Figure 8 shows that on the second braking section, after the 
speed is reduced by 2 times (from 40 to 20 km/h), the braking path 
decreases quickly. Thus, on the first braking section at speed 
reduction from 40 to 20 km/h, it was 18 m, and on the second 
braking section – only 12 m. 
 
Figure 8 – Dependence of the braking path on the speed of the 
vehicle during braking by the service braking system from the initial 
speed of 40 km/h in emergency and service braking. 
Thus, the analysis showed that the power of mechanical losses 
of a modern passenger vehicle engine is not sufficient for continuous 
braking by the engine in urban conditions. To ensure effective 
service braking of a car by an engine, the average deacceleration and 
average power of mechanical losses of an internal combustion engine 
should be increased by 1.8-2.1 times. 

47 

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