Note: Descriptions are shown in the official language in which they were submitted.
1 3 1 3047
A heating and air conditioning system for a coach
The invention relates -to a heating and air
conditioning system for a coach or the like, comprising
an air intaks channel with an air intake hole at its one
end opening outside the vehicle and feeding the intake
air through a heat exchanger of water circulation type
inside the vehicle.
The known heating and air conditioning systems
for coaches show an air intake down in the front end of
the motorcar. Then exhaust gases from the traffic around
easily drift inside the motorcar, which can prove to be
very annoying, especially in city traffic. Exhaust air
valves are generally situated in the rear end of the
body so that the passenger space can be provided with
a suficient air circulation. The air 10ws in the
passenger space from t~e front backwards to a distance
of even 12 meters. Then the old indoor air flowing
backwards in the passenger space is mixed with the
intake air, which makes the refreshing effect of the
intake air weaker. Moreover, auxiliary blowers in the
front end of the motor car mix the air flows in the pas-
senger space and make the air conditioning even worse.
According to the regulations, the inside air of the
vehicle should be changed at least 10 times an hour,
but in the known solutions this is in the most cases
not sufficient to guarantee a good air quality for the
passengers.
In the known systems, the intake air is heated
by means of a heat exchanger, through which the cooling
liquid o~ the motor i5 circulating. The cooling system
of the motor can be connected to the heat exchanger by
means of a three-way valve, whereby the heat exchanger
in a way has its own hydraulic circulation, in which the
temperature of the circulating liquid can be controlled
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1313047
by means of said three-way valve. Through this arrange-
ment it is possible to compensate the slow changes
occurring in the temperature of the intake air or of
the passenger space. Quick temperature changes cannot,
however, be corrected by this arrangement.
The object of the invention is thus a heating
and air conditioning system for a coach, by means of
which quick temperature changes can be corrected.
Another object of the invention is an improved
air circulation in the passenger space.
This is attained by means of a heating and air
conditioning system of a type described in the prior
art portion, which is characterized in that the system
additionally comprises a preliminary heat exchanger in
the air intake channel between the air intake hole and
the heat exchanger, an exhaus-t air channel extending
from the inside through the preliminary heat exchanger
and opening outside the vehicle, and control means,
through which the amount of intake air to be led from
the air intake channel into the heat exchanger can be
restricted to compensate quick temperature changes, if
necessary, and through which exhaust air from the ex-
haust air channel can be led instead into the heat
exchanger.
The air is taken in from above the windscreen,
because the boost pressure is there at its highest and
the air is better in quality than below the windscreen,
from where the air intake normally occurs.
The indoor air is led out by means of the exhaust
channel ending preferably in the front end o the roof,
because the underpressure is greatest in the front end
of the roof for the provision of a stronger suction and
a better air circulation. Air flows are mainly directed
from above downwards, because the fresh intake air is
fed separately for each passenger and the exhaust air
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is correspondingly fed through exhaust valves in the
bo-ttom part of the passenger space into the exhaust
channel. Air flows in the longitudinal direction of the
passenger space do mainly not occur. A good air quality
is obtained even by means of a less ventilation as is
stipulated. The exhaust air flows through the prelimi-
nary heat exchanger placed in the air intake channel
and emits heat into the air coming in, whereby separate
auxiliary heaters are avoided, if a sufficient amount
of heat is not obtained from the cooling liquid of the
motor for heating the coach. It is detrimental to the
motor, if its cooling liquid is below 60C and a tem-
perature lower than this is hardly enough any more for
heating the intake air~ In summer the preliminary heat
exchanger can be used as a precooler, when the air
temperature must be cooled mechanically.
Said control means can lead, if necessary, all
the exhaust air through the heat exchanger back to the
passenger space, for instance when there are quick
changes in the temperature of the air coming from out-
side, which changes cannot be corrected quickly enough
by corrections of the temperature of the circulating
water. A recirculation of the exhaust air speeds up
also the heating of the passenger space before starting
driving. ~ recirculation is preferable for maintaining
a sufficient temperature when opening the door and
immediately thereafter. When the door is open and the
control flap is in a circulating position, it is
preferable that a blower connected to -the heat exchanger
operates at full capacity, whereby the air circulation
speeds up and the cold air flowing in through the open
door can be led quickly out of the passenger space while
warm air is fed in instead.
The invention is described in the following in
3.~ closer detail by means of an embodiment with reference
1 3 1 3047
of the enclosed drawing, in which
Figure 1 shows a side section view of a heating
and air conditioning system according to the invention
located in a coach, and
Figure 2 shows a block diagram of an electronic
control system of the system according to Figure 1.
As shown in Figure 1, there is an air intake
channel 1 in the front end of the coach in the upper
portion of the driver's cabin immediately below the
roof, which channel runs in the longitudinal direction
of the vehicle with its front end opening in front of
the car above the windscreen and forming an air intake
hole 2 in the form of a hopper. At the rear end of the
air intake channel 1 there is a blower and a heat ex-
change cell 3 of water circulation type, which cell
heats the intake-air and feeds it into a distributing
channel in the upper portion of the pass~nger space in
the longitudinal direction of the car.
Below the air intake channel 1 there is a
parallel exhaust air channel 4, the first portion of
which forms a vertical rising channel 11 preferably
beginning from a boot below the passenger space. A
preliminary heat exchanger 5 is located in the air
intake channel 1 between the air intake hole 2 and the
heat exchanger 3, through which preliminary heat e~-
~changer the intake air flows along horizontal pas-
sages. The exhaust air channel ~ ends below the prelimi-
i
nary heat exchanger 5, from where the exhaust air con-
tinues upwards along the vertical passages of the pre-
liminary heat exchanger 5 and ends outside the car
through an exhaust hole 6 in the roof above the prelimi-
nary heat exchanger 5. Then the warm exhaust air flowing
through the preheater 5 heats the intake air flowing
in the air intake channel 1.
Between the preliminary heat exchanger 5 and
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1313047
the heat exchanger 3, the wall of the bottom of the
air intake channel 1, i.e. the partition wall between
the air intake channel l and the exhaust air channel 4,
is formed by a control flap 7. The control flap 7 is
articulated in the middle by an axle 8 transverse to
the channels. Thus the control flap 7 can turn from a
hori~ontal position parallel with the channels 1 and
4, in which position it separates the channels from each
other and leads the inta~e air into the heat exchanger
3 and the exhaust air into the preliminary heat ex-
changer 5, to a vertical position, in which it leads
exhaust air into the heat e~changer 3. In the example,
the control flap 7 has two operating positions. By means
of a structure of another kind intake air and exhaust
air can also be led as a mixture desired to the heat
exchanger.
The control of the control flap 7 occurs on the
basis of a measurement carried out by means of a tempe-
rature indicator 12 in a way ~o be described later.
~t the first end of a distributing channel 9,
immediately after the heat exchanger 3 and the blower
(not shown) is located a measuring flap 10, which is
situated in the distributing channel 9 in an upright
position and transversally to the ~lowing dir~ction.
The upper end of the measuring flap 10 is fastened
pivotally in such a way that the air flow coming from
the heat exchanger can turn the flap 10 with respect
to the vertical plane to an angle proportional to the
flow~rate or air pressure in the distributing channel
9. This turning angle is measured by means of a suitable
indicator, e.g. by means of a potentiometer 22 (Figure
2), conneated to the end of the axle of the measuring
flap 10. A control unit 21 shown in Figure 2 controls
the speed of rotation of the blower on the basis of this
measuring value by means of a suitable motor control
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unit 25. In this way the flow rate in the distributing
channel 9 can be maintained essentially constant ir-
respective of changes in the boost pressure.
The bottom of the distributing channel is at
regular distances provided with openings 14 provided
with ribs, between which ribs air is evenly distri-
buted all over the passenger space. The ribs are
preferably pipes, in which the cooling liquid of the
motor circulates and heats the air passing by. In the
bottom part of the passenger space there are corre-
sponding openings 15 at regular distances, through which
openings the indoor air flows into a boot 16 and further
through the exhaust channel 4 out of the car. The
strong suction caused by the great underpressure at the
exhaust hole 6 in the front end of the roof provides
an effective air circulation. If desired, the underpres-
sure can be increased at the front edge of the roof by
means of a raising 18 before the exhaust hole 6.
The heat exchange cell 3 can also be a double-
cell, in which in addition to the cooling liquid of the
motor also a cooler for cooling indoor air at warm
seasons can be circulated. Then also the cool exhaust
air cools the intake air in the preliminary heat ex-
changer.
Figure 2 shows a bloc~ diagram of an electronic
control system according to the invention. To the
control unit 21 are connected the temperature indicator
1~, the potentiometer 22, flap control 23, control 24
~of the three-way valve and blower control 25.
~` 30 The temperature indicator located after the
heat exchanger 3, e.g. in the distributing channel 9,
develops a measuring signal. On the basis of this signal
the control unit 21 controls the flap ~ and the three-
way valve controlling the temperature of the cooling
liquid of the motor circulating through the heat
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e~changer ~. When the temperature measured decreases
~uickly from the set value, the control unit 21 turns
the control flap 7 to an upright position. Simulta-
neously, the three-way valve is controlled in such a
way that the temperature of -the circulating liquid
begins to rise. The control flap 7 is turned to a
horizontal position after the predetermined period has
expired ~delay in the control of the liquid temperature)
and/or after some other condition is fulfilled. During
the time of opening the door, the control unit 21 can
be arranged to control only the control flap 7.
The potentiometer 22 develops a signal propor-
tional -to the air pressure acting on the measuring
flap 10, on the basis of which signal the control unit
21 steplessly controls the speed of rotation of the
blower.
The bloc~s according to Figure ~ can be easily
realized by means of commercially available control
circuits and units. The control system aan naturally
be realized also in other ways different from the
above.
The figures and the specification relating
thereto are only meant to clarify the invention. As to
the details, the heating and air conditioning system
according to the invention can vary within the scope
of the enclosed claims.
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