Method and apparatus for air conditioning motor vehicles

A method and apparatus are described for air conditioning motor vehicles by the use of an absorption-type system, wherein: a concentrated solution is introduced into the vehicle engine block, causing a volatile refrigerant in the solution to be evaporated; during a cooling mode, the evaporated refrigerant is condensed, the heat so produced being rejected externally to the automobile, the pressure of the refrigerant is reduced to reevaporate it and thereby to cool the motor vehicle interior, the pressure of the dilute solution leaving the automobile engine block is reduced, the refrigerant is remixed to reconstitute the concentrated solution, and the so reconcentrated solution is repressurized and recycled to the engine block; and utilizing the dilute solution from the engine block during the heating mode for heating the motor vehicle interior by directing the dilute solution into heat-exchange relationship with the interior of the motor vehicle, while accumulating in the condenser the refrigerant leaving the engine block.

BACKGROUND OF THE INVENTION 
The present invention relates to a method and apparatus for air 
conditioning motor vehicles. 
The presently used systems for air conditioning motor vehicles usually 
include a compressor for increasing the pressure of the refrigerant gas to 
a point where liquefaction may occur in the condenser. Compressor-type air 
conditioners, however, have a number of drawbacks when used in motor 
vehicles. One serious drawback is that they reduce the driving power 
output of the vehicle engine to such an extent that compressor-type air 
conditioners can normally be used only with automobiles having relatively 
large engines. In addition, compressor-type air conditioners increase the 
fuel consumption as much as 15% or 20%. Further, they are relatively 
expensive and require continuous maintenance. 
There have been prior proposals to air condition motor vehicles by the use 
of absorption-type systems, wherein heat, rather than mechanical work, is 
used as the primary energy source for the refrigeration cycle. These 
previously proposed absorption-type air conditioners generally used 
heat-exchangers for extracting heat, either from the vehicle radiator, or 
from the hot engine exhaust gases, or from both. However, they were 
generally found not commercially satisfactory for a number of reasons. 
Thus, the extraction of heat from hot exhaust gases requires a large heat 
transfer area. In addition, heat-exchangers produce a pressure drop in the 
vehicle exhaust pipe system, thereby reducing engine efficiency. Further, 
the extraction of heat from hot exhaust gases produces serious corrosion 
problems. 
On the other hand, it has been found impractical to utilize the radiator as 
a sole source of energy because of its relatively low temperature, 
although the quantity of heat present there is quite high. 
BRIEF SUMMARY OF THE INVENTION 
An object of the present invention is to provide a new method and 
apparatus, based on an absorption system, for air conditioning a motor 
vehicle. 
According to one aspect of the present invention, there is provided a 
method for air conditioning a motor vehicle by selectively cooling or 
heating same during a cooling mode and a heating mode of operation, 
respectively, comprising: introducing into the vehicle engine block a 
concentrated solution of a solvent and a volatile refrigerant for heating 
same to evaporate volatile refrigerant from the concentrated solution, 
thereby leaving a dilute solution; utilizing the evaporated refrigerant 
from the engine block during the cooling mode for cooling the motor 
vehicle interior by condensing the evaporated refrigerant and rejecting 
the heat so produced external to the automobile, reducing the pressure of 
the refrigerant to reevaporate same and to cool thereby the motor vehicle 
interior, reducing the pressure of the dilute solution leaving the 
automobile engine block, remixing the refrigerant in the dilute solution 
to reconstitute the concentrated solution, repressurizing and recycling 
the reconstituted concentrated solution to the engine block; and utilizing 
the dilute solution from the engine block to heat the motor vehicle during 
the heating mode, by directing said dilute solution into heat-exchange 
relationship with the motor vehicle interior while accumulating in said 
condenser the refrigerant leaving the engine block. 
According to another aspect of the invention, there is provided apparatus 
for air conditioning a motor vehicle, comprising: conduit means for 
introducing into the vehicle engine block a concentrated solution of a 
solvent and a volatile refrigerant, which refrigerant is evaporated from 
the concentrated solution by the heated generated in the engine block, 
thereby leaving a dilute solution; a condenser condensing the evaporated 
refrigerant and rejecting the heat so produced external to the automobile; 
an expansion device reducing the pressure of the condensed refrigerant; an 
evaporator evaporating the condensed refrigerant and cooling thereby the 
motor vehicle interior; a liquid regulating device reducing the pressure 
of the dilute solution; an absorber remixing said dilute solution from the 
engine block and the refrigerant from the evaporator to reconstitute the 
concentrated solution; return conduit means including a pump for recycling 
the remixed solution back to the engine block under pressure; and control 
means for selectively controlling the apparatus to operate according to a 
"cooling" mode to cool the interior of the motor vehicle, or a "heating" 
mode to heat the interior of the motor vehicle; said control means 
including valve and by-pass means effective during the cooling mode to 
utilize the evaporated refrigerant to cool the interior of the vehicle by 
directing same to said condenser, expansion device and evaporator; said 
valve and by-pass means being effective during the heating mode to utilize 
the dilute solution from the engine block to heat the interior of the 
motor vehicle while accumulating in said condenser the refrigerant leaving 
the engine block. 
In the preferred embodiment of the invention described below, the absorber 
replaces the automobile radiator or is a modification thereof. 
In one described embodiment, the apparatus includes a heater, said valve 
and by-pass means directing the dilute solution from the engine block 
through the heater during the heating mode of operation. More 
particularly, the latter means comprises a by-pass line from the dilute 
solution exit of the engine block, to the heater, and back to the 
concentrated solution inlet to the engine block, a first control valve in 
said by-pass line effective to enable same during the heating mode, and a 
second control valve between the condenser and the evaporator and 
effective to disconnect the evaporator during the heating and off modes, 
thereby to cause the refrigerant to accumulate in the condenser. 
In a second, less-expensive, described embodiment, a separate heater is not 
provided, and instead, the condenser is used for heating the interior of 
the motor vehicle. In this embodiment, the apparatus includes a line 
between the dilute solution outlet of the engine block and the inlet end 
of the evaporator, the first control valve in said latter line which valve 
is closed during the cooling and off modes, and open during the heating 
mode; and a second control valve between the condenser and the evaporator 
which valve is open during the cooling mode and closed during the heating 
and off modes. 
Further features and advantages of the invention will be apparent from the 
description below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to FIG. 1, the vehicle engine block is schematically 
illustrated at G, and constitutes the generator of the system. A 
circulation pump P, which may be the conventional cooling water pump 
provided in existing vehicle engines or a modification of it, introduces 
into the vehicle engine block G, under pressure, a concentrated solution 
of a solvent and a volatile refrigerant. As an example, the solvent may be 
DME-TEG (Dimethyl Ether-Tetra Ethylene Glycol) and the volatile 
refrigerant may be Dichloromonofluoromethane (commonly called "Refrigerant 
21", or "Freon 21"). This solution is used for the normal cooling of the 
engine block, so that it is heated by the heat generated within the engine 
block. The same solution may also be used, in the "heating" mode of 
operation, for heating the interior of the motor vehicle. The selection of 
the mode of operation of the system is determined by four control valves 
CV.sub.1 -CV.sub.4, as will be described below. 
The heat generated within the engine block G causes refrigerant to 
evaporate. The evaporated refrigerant passes through an analyser AN, 
separating solvent droplets from the refrigerant vapour, and exits via a 
line 2 to a rectifier R, which is a reflux condenser. The refrigerant 
vapour then passes through line 4 to a condenser C. 
The refrigerant vapour is condensed in condenser C and passes through an 
output line 6 to a receiver REC for accumulating surplus refrigerant 
during the operation of the system, and for compensating for minor leaks 
of refrigerant to the atmosphere. The condensed refrigerant then passes 
via line 8 to a heat-exchanger HX.sub.1, and from there, via control valve 
CV.sub.2, a strainer S and an expansion device EV to an evaporator E. 
Strainer S filters condensed refrigerant flowing in the liquid line 8, and 
expansion device EV reduces the pressure of the condensed refrigerant gas 
such that part evaporates there and the remainder evaporates in the 
evaporator E. The gas vapour exits from evaporator E via line 10 and flows 
back through the heat-exchanger HX.sub.1, and from there, via line 12 and 
control valve CV.sub.2 to the absorber A. 
The evaporation of the refrigerant gas in evaporator E extracts heat from 
the interior of the motor vehicle, and thereby cools it. In heat-exchanger 
HX.sub.1, the cold evaporated refrigerant exiting from the evaporator E is 
used to cool the hot liquid refrigerant exiting from the condenser C and 
the receiver REC via line 8. This lowers the enthalpy of the liquid 
refrigerant so that it can absorb more heat in the evaporator from the 
interior of the motor vehicle. 
In absorber A, the gaseous refrigerant from the evaporator E is remixed 
with the dilute solution from the engine block G in order to reconstitute 
the original concentrated solution before the latter is recycled back into 
the engine block. Thus, the dilute solution leaves the engine block via 
outlet line 14, has added thereto the dilute solution separated in the 
rectifier R and supplied thereto via line 16, and is then passed through a 
heat-exchanger HX.sub.2 where its heat is used for preheating the 
reconstituted concentrated solution passing through the heat exchanger to 
the engine block via lines 18 and 20. The dilute solution exiting from the 
heat exchanger HX.sub.2 passes via line 22 to a regulating valve EV where 
its pressure is reduced before being introduced into the absorber A with 
the gaseous refrigerant. The concentrated solution reconstituted in 
absorber A is recycled by circulation pump P through heat-exchanger 
HX.sub.2 back into the engine block G via inlet line 20 as described 
above. 
The system, insofar as described above, will thus operate in a "cooling" 
mode, whereupon the evaporator E will extract heat from the interior of 
the motor vehicle, while the condenser C and the absorber A will reject 
heat to the exterior of the motor vehicle. 
In addition to the "cooling" mode of operation, the system can also operate 
in two other modes, namely a "heating" mode wherein the interior of the 
motor vehicle is heated, and an "off" mode wherein both cooling and 
heating are disabled. 
For this purpose, the system in FIG. 1 includes a heater H and by-pass 
means for directing the dilute solution therethrough from the engine block 
during the heating mode of operation when the interior of the motor 
vehicle is to be heated. The by-pass arrangement includes a line 26 
directing the hot dilute solution from the dilute solution outlet line 14 
through control valve CV.sub.1 to the heater H, and a second line 27 from 
the heater directly to the circulation pump P, thereby bypassing the 
absorber A. During the heating mode, control valve CV.sub.1 is open, 
thereby enabling the by-pass line through the heater H; and control valve 
CV.sub.2 between the receiver REC and the evaporator E is closed, thereby 
causing the refrigerant to accumulate in the condenser C or the receiver 
REC, and not to be circulated to the evaporator E. 
The system illustrated in FIG. 1 also includes a line 28 by-passing the 
regulating valve RV, there being a thermostat T and a control valve 
CV.sub.4 in line 28. The latter thermostat and control valve are 
effective, during the heating mode to direct all the dilute solution from 
the engine block G to the heater H while the engine is relatively cold, 
and to direct a part of the dilute solution from the engine block to the 
absorber after the engine has become warm. 
The following table illustrates the conditions of the four control valves 
CV.sub.1 -CV.sub.4 during each one of the three above-described modes of 
operation of the system: 
______________________________________ 
Valve/Mode Cooling Heating Off 
______________________________________ 
CV.sub.1 Closed Open Closed 
CV.sub.2 Open Closed Closed 
CV.sub.3 Open Closed Closed 
CV.sub.4 Closed Open Open 
______________________________________ 
FIG. 2 illustrates a lesser-expensive arrangement that may be used still 
providing the three modes of operation, but obviating the need for a 
separate heater (corresponding to heater H, FIG. 1). Instead of the 
heater, the evaporator of the air conditioning system is used for heating 
the interior of the motor vehicle during the heating mode. 
Thus, in FIG. 2, the system includes the engine block generator G, analyser 
AN, condenser C, receiver REC, expansion valve EV, evaporator E, 
regulating valve RV, absorber A, circulating pump P, and heat exchanger 
HX.sub.2, all performing similar functions as described above with respect 
to FIG. 1 and therefore carrying the same reference characters. In 
addition, a by-pass line 28 is provided bypassing the regulating valve RV, 
this line including a thermostat T and a control valve CV.sub.4 ', as in 
the correspondingly identified elements in FIG. 1. 
In the system of FIG. 2, however, a line 126 is provided between the dilute 
solution exit of the engine block G and the inlet of the evaporator E. 
This bypass line includes a control valve CV.sub.1 ' which is closed 
during the cooling and off modes and opened during the heating mode. In 
addition, a second control valve CV.sub.2 ' is provided between the 
condenser C and evaporator E at a point upstream of line 126, control 
valve CV.sub.2 ' being open during the cooling mode and closed during the 
heating and off modes. 
It will thus be seen that during the cooling mode, control CV.sub.2 ' is 
opened permitting the refrigerant gas from the condenser C and receiver 
REC to be fed, after expansion in valve EV, to the evaporator E where it 
effects the cooling of the interior of the motor vehicle as described 
above. However, in the heating mode, control valve CV.sub.2 ' is closed 
and control valve CV.sub.1 ' is opened, thereby causing the gaseous 
refrigerant to accumulate in the condenser C and the receiver REC, and the 
hot dilute solution exiting from the engine block to be fed to the 
evaporator where it heats the interior of the motor vehicle and then 
returns to the engine block via the absorber A and the heat-exchanger 
HX.sub.2. 
Many other variations, modifications and applications of the invention will 
be apparent.