305
REVO-E Heat pump
3 Assemblies and components
3.5
Design / task and function of
the assemblies
The REVO-E heat pump features an outer and an inner
heat exchanger.
They consist of aluminum tubes and aluminum fins which
are jointly connected and form a large heat exchanger
surface.
Outer heat exchanger
In the air-conditioning mode it works as condenser. If the
unit is in the heat pump mode, it is working as evaporator.
Inner heat exchanger
In the air-conditioning mode they work as evaporator. If
the unit is in the heat pump mode, they are working as
condenser.
Condenser function
It cools the hot refrigerant gas in such a way that it lique-
fies, subcools and transfers the condensation heat to the
external air flowing through it via the fins.
Evaporator function
The evaporator absorbs the heat from its environment and
delivers it to the refrigerant. In this process the evapora-
tion temperature must be lower than the ambient temper-
ature.
By the simultaneous suction action of the refrigerant
compressor and the constriction of the expansion
member, the desired evaporation temperature can be
achieved in a targeted manner.
The heat flowing because of the temperature difference
between the evaporator and the environment causes the
refrigerant liquid fed in by the expansion element to evap-
orate (evaporation zone) and to overheat (overheating
zone) in the evaporator.
Compressor (HGX34P/315-2 A)
This semi-hermetic, 4 cyl. reciprocating compressor is
driven by a 2 pole, asynchronous motor integrated into the
housing. It is flushed / cooled by R134a, a gaseous refrig-
erant, and an integrated PTC element monitors the
temperature level. Signals are evaluated by the frequency
converter. The frequency converter also provides power
and controls the speed.
The duty of the compressor is to condense vaporous
refrigerant from low pressure to a higher pressure. To do
so, it must ensure the necessary discharge (refrigerant
flow) required for cooling.
The compressor is integrated into the air-conditioning
system. The compressor with patented vibration decou-
pling design is created using a special absorption foam.
The compressor is embedded and fixed in this foam.
Receiver
The receiver is a compensating/ storage tank which
balances out changes in the refrigerant circuit.
Dryer
The interior of the dryer contains a granulate that removes
small amounts of water from the refrigerant and chemi-
cally binds to it.
The dryer also filters contaminates from the refrigerant
that might lead to malfunctions.
A further expansion valve for heat pump operation is
installed in the heat pump.
Thermostatic expansion valve
The thermostatic expansion valve with external pressure
equalization regulates the refrigerant flow to the
compressor, depending on the refrigerant needs or the
condenser temperature. The thermostatic expansion
valve is the control element between the high and low
pressure sections of the refrigerant circuit.
Pressure switch
The high and low pressure switches are installed on the
compressor and are a key component of the safety chain
of the air-conditioning system.
High pressure switch
–
Monitors the pressure level in the high-pressure area
of the refrigerant circuit
–
Deactivates the air-conditioning system if pressure is
too high (e.g. too much refrigerant)
Low pressure switch
–
Monitors the pressure level in the low-pressure area
of the refrigerant circuit
–
Deactivates the air-conditioning system if pressure is
too low (e.g. too little refrigerant)
–
The low pressure switch is not installed in the
11123865_ and is replaced by an SW algorithm.
Switch point
1
) not in 11123865_
Axial fans
The three axial fans are driven by EC motors.
If Cooling Mode is activated, the fans are continuously
controlled depending on the load (refrigerant pressure)
via the PWM, and provide the outer heat exchanger with
sufficient fresh air.
Switch point
High pressure
switch
Low pressure
switch
1
On
19 ± 1.5 bar
(relative)
1.8 ± 0.3 bar
(relative)
Off
24 ± 1.0 bar
(relative)
0.3 ± 0.3 bar
(relative)
Summary of Contents for REVO-E
Page 1: ...Rev 06 2019 Id No 11123006A REVO E Heat pump Volvo Workshop Manual AIR CONDITIONING...
Page 51: ...605 REVO E Heat pump 6 Wiring plan Fig 601 Wiring diagram for REVO E HP Sheet 4...
Page 52: ...606 REVO E Heat pump 6 Wiring plan Fig 601 Wiring diagram for REVO E HP Sheet 5...
Page 55: ...609 REVO E Heat pump 6 Wiring plan Fig 602 Wiring diagram for REVO E HP Sheet 1...
Page 56: ...610 REVO E Heat pump 6 Wiring plan Fig 602 Wiring diagram for REVO E HP Sheet 2...
Page 57: ...611 REVO E Heat pump 6 Wiring plan Fig 602 Wiring diagram for REVO E HP Sheet 3...
Page 59: ...613 REVO E Heat pump 6 Wiring plan Fig 602 Wiring diagram for REVO E HP Sheet 5...
Page 87: ...memos...