DE2412587A1 - AIR CONDITIONING FOR A MOTOR VEHICLE - Google Patents

Description

PATENT LAWYERS

MANITZ, FINSTERWALD & GRÄMKOW

Munich, the tu. YuI ^a We / Sv - G 3009

GrJfiNEHAL MOTOHB Οϋ ± ίΡΟΗΑΐΙΟΝ Detroit, Michigan, USA

Air conditioning for a motor vehicle

The invention "relates to an air conditioning system for a motor vehicle.

It is known that in an air conditioning system of a motor vehicle, a cooling compressor is operated by the internal combustion engine of the motor vehicle is driven, the speed of which changes over a relatively large range. The pumping or compression capacity of the compressor is proportional to changes in engine speed. This variable compression capacity directly affects the cooling efficiency of the system as the cooling capacity of the evaporator at any given ambient temperature is limited by heat transfer phenomena, specifically with regard to the design of the cooling fins.

Unfortunately, changes in compressor capacity can be made not easy to settle in order to agree with the To achieve the cooling capacity of the evaporator. This means that the compressor capacity exceeds when the outside temperature is low ■ usually the ability of the evaporator to generate heat from the air

409842/0302

DR. G. MANITZ · DIPL.-ING. M. FINSTERWALD DT PL. -ING. W. ORAMKOW ZENTKALKASSE BAYER. POPULAR THANKS

β MUNICH 22. ROBERT-KOCH-STRASSE I 7 STUTTGART 50 (BAD CANNSTATT) MUNICH, ACCOUNT NUMBER 7370

TEL. fOe9i 33 42 II, TELEX 08-29673 PATMF SEELBERGSTR. 33/35. TEL. (0711) 56 72 61 POSTSCHECKi MÖNCHEN 77062-805

remove which flows over its outer surfaces. Under such conditions the cooling pressure inside the evaporator decreases, due to an excessive supply of coolant and due to incomplete evaporation of the coolant in the evaporator. Also the increasing rate of delivery from the evaporator back to the compressor during operation at high The speed of the compressor reduces the evaporator pressure and temperature. The coolant temperature eventually drops below the pressure, which corresponds to a freezing temperature on the outside of the rib surfaces of the evaporator. if the rib surface temperature drops below freezing point, Usually ice begins to build up on it. The ice build-up is undesirable because it reduces the rate of heat transfer between the air and the construction of the evaporator and finally the Blocked air flow through the evaporator.

A device is to be created which prevents the coolant temperature in the evaporator from falling below the level which corresponds to the freezing temperature on the outer surfaces of the fins of the evaporator.

It is known to use throttle valves which control the evaporator pressure determine in order to control the pressure in the evaporator, for example by means of an evacuated bellows. There are already external ones Sensors or sensors on the outside of the evaporator have been used to detect ice build-up and around defroster equipment switch on, for example by switching off the compressor.

According to the invention, an evaporator temperature control device created within a coolant-KIissigkeii-s-accumulator device has a throttle valve assembly.

409842/0302

2Ä12587

The invention is explained below, for example, with reference to the drawing described; in this show:

! Fig. 1 is a schematic representation of an air conditioning system for a Motor vehicle,

Sig. 2 a vertical section of the liquid shown in Pig.1

keitsakkumulators, which the actuatable by freezing. Has a throttle valve,

J ¹ Ig. 3 is a graph showing the freezing characteristics of two STuiden, wherein in the bar diagram the left end of the bar represents the crystallization temperature and the right end of the bar represents the freezing temperature,

Pig. 4 is a graph showing the refrigerant temperature is plotted over time, in an evaporator accumulator under low and high ambient temperatures and when using a silver iodide-water mixture in the valve actuator and

£ "± g. 5 is a graph of coolant temperature versus Time, in an evaporator accumulator, in which distilled water is used in the valve actuator showing the corresponding freezing temperature of the core of the evaporator.

In FIG. 1, an air conditioning system is shown, "which has a refrigerant compressor 10 has. The drive shaft of the compressor 10 is connected to a roller assembly 12 which is through a The engine of the motor vehicle is driven by belts (not shown), polygons extending through the grooves 14 of the roller 12. The outlet 16 of the compressor 10 is connected to a flexible pipe 20 by a corresponding connection device 18, which in turn is connected to the inlet 22 of a condenser 24 via a corresponding connection device 26.

409842/0302

The capacitor 24 is formed so that it is in the vicinity the front of the motor vehicle is arranged such that it is exposed to a flow of air into the grille and the warm coolant therein is liquefied. The outlet 28 of the condenser is fluidly connected to a capillary expander 30 to reduce the pressure of the liquid coolant to reduce which is taken up by the capacitor 24.

The expander 30 is connected to the inlet 32 of an evaporator 34 connected, in which coolant in parallel tubes 36 vaporizes, with each tube connected to eluid line parts and has outer rib surfaces that are integral Form part of each other. The evaporator 34 has an outlet 38, which is connected to an inlet of a liquid accumulator 40 ally is. The liquid accumulator 40 separates liquid from the vaporous coolant and releases vaporous coolant through an outlet into a suction line 42. The suction line 42 is through a corresponding connection device 44 to the inlet 46 of the compressor 10 is connected. The accumulator also serves to store excess coolant, which serves to compensate for small leakage losses of coolant.

As has already been stated above, when the air conditioning system is in operation, "at low ambient temperatures, the heat transfer from the through the air flowing through the tube 36 of the evaporator 34 is insufficient. Consequently the heat transfer is not sufficient to evaporate coolant sufficiently quickly in the evaporator, so that its internal pressure over is maintained at a level approximately equal to freezing point. In accordance with the invention there is provided a thermally responsive throttle valve assembly 48 is provided, within the accumulator 40, in order to reduce the flow of refrigerant from the evaporator below this To reduce ambient temperatures and consequently to increase the internal pressure of the evaporator.

409842/0302

The accumulator consists of a tubular element 50 which has a closed end 52 and an interior space 54. An open upper end of the tubular element 50 is covered by an end piece 56 which has an inlet part 58 which is designed such that it is in fluid communication with the evaporator outlet 38. An outlet part 60 is designed in such a way that it is in fluid communication with the sales line 42. An inlet line 62 leads a mixture of liquid and vaporous coolant into the interior 5 ¹ ^ from. Evaporator 34. A weld 64 between the end piece 56 and the tubular element 5 ° seals the coolant in the space 54, and an O-ring 66 arranged within a groove 68 prevents a leak between the elements 50 and 56 Outlet pipe 70 delivered into end piece 56. It then goes through the suction line 42 to the inlet 46 of the compressor 10.

A drying assembly 72 is in the floor of the interior space 54 held by a corresponding support element 74. The drying arrangement 72 ″ has an outer skin 76 made of porous material on, which encloses a certain amount of silica gel 78. That Silica gel absorbs any moisture that may accidentally be mixed with the coolant.

The coolant temperatures in the evaporator are monitored directly, through the throttle valve assembly 48, which is in the interior 54 is held by a tubular valve seat element 80. An upper end of the element 80 is disposed in a groove 82 which is machined within the end piece 56. The valve seat element 80 carries an O-ring 84 in a groove 86 to prevent coolant leakage to prevent in the bypass to the valve. An expandable snap ring retainer 88 holds the valve seat member in place the recess 82. The valve seat element 80 has a partition wall

409842/0302

which has a passage 92 and further a valve seat 94 which is formed on the upper end of the wall 90. normally coolant flows through the inlet pipe 62 into the interior * -. * + of the accumulator where liquid coolant is separated and directed to the bottom of the accumulator in sight "until it evaporates, while vaporous coolant through passage 92 to E. outlet 70 of the accumulator and from there through the suction line 42 to the inlet 46 of the compressor 10.

The valve seat member 80 has a tubular string portion 96 upstream of the passage 92 which surrounds a temperature sensitive valve actuator 98 to allow it to reciprocate in the passage 92. The actuating device 98 has an elongated tube part 100 which extends to the lower end 52 of the accumulator 40. An annular valve element 102 is disposed around the upper end of the tubular element 100 adjacent the valve seat 94. A hollow bellows 106 is attached to the valve element 102 downstream of the valve seat 94; It has an element which is cylindrical in its entirety and which is formed by a ribbed side wall 108. The interior of the tubular element 100 and the bellows 108 are in eluid connection, namely through a bore 104 through a valve element 102. The tubular part 100 is almost completely filled with an aqueous solution 111 which has a desired freezing temperature control of about ⁰ G for the parallel passage evaporator shown. The remaining part of the pipe part 100 and the interior of the bellows 106 are filled with a liquid 113 such as oil, which has a solidification temperature that is substantially below freezing point and is immiscible with the aqueous solution.

When the 'temperature of the coolant in the interior of the accumulator 40 drops below freezing point, the solution 111 begins to crystallize and solidify. Before this happens its volume increases, and that between the solution 111 and the

409842/0302

Meniscus 115 formed by liquid 113 is ^{moved upward as shown in FIG. B 1} Xg.2 and exerts pressure on flexible walls 108 of bellows 106. This causes the bellows 106 to expand in the axial direction. The upper end of the bellows 106 is equipped by a corresponding base part 117 with an overload safety device 119, which is held pressed against the valve seat element 80 by an overload spring 121. When the bellows 106 expands in the axial direction, the valve element 102 move and cL & s tubular element 100 according to Fig. 2 downwards against the resistance force of the valve spring 123, and zxfar towards the valve seat 94. This reduces the coolant flow through the line 92. ^When the total solution 111 has solidified, the valve element 102 should be in the Engage valve seat 94 to completely block coolant flow through conduit 92. If further expansion of solution 111 occurs in tubular stem 98 after valve element 102 engages valve seat 94, bellows 106 moves the retainer 119 according to FIG. 2 upwards against the overload spring 121. This prevents an excessive D jerk acts on the valve element 102 on the valve seat 9 ^, which could otherwise damage the actuating device 98 and cause it to freeze. In addition to protecting the actuating device, the use of the overload holding device 119 and the overload spring 121 have a further important function or a further important advantage. The overload device has sufficient flexibility such that the valve arrangement does not require any special calibration. The valve automatically positions itself so that the freezing point control effect occurs when the liquid is at 111 water. Placing the actuator 98 downstream of the valve 102 would not accurately determine the evaporator temperature because when the valve begins to close, the coolant flow is reduced and the coolant temperature can be affected by a throttling effect during passage through the valve.

4Q9842 / Q3G?

-s-

The compressor 10 is lubricated by oil mixed with the Coolant is transported through the system. A natural iaum for oil that it can collect in the system is the bottom of the accumulator 40. normally carries when the line 92 is open, the Kühlraitt el flow is sufficient Amount of oil for sufficient lubrication to the compressor. However, if line 92 is closed, no oil is sent to the Compressor transported to allow oil flow, When the valve 102 is closed, an additional device is provided which has an oil on acceptance ear 125 and which is held by the valve seat element 80 to remove oil from the floor of the accumulator 40 and pull it downstream from the valve element 102 to submit. A small opening 127 is provided in the valve seat element 80 in order to provide the compressor with an adequate opening To supply oil. When valve 102 is in a closed position, line 92 is blocked, the pressure downstream of the valve 102 is substantially less than that in the interior 54 of the accumulator 40, and thus the pressure difference between the Interior 54 and the outlet 70 cLes accumulator the driving Force to. Lifting the oil through the pick-up tube 125-

An essential feature of the invention is that a oil-filled isaig is available, which is in pluid connection with the tubular part of the freezer that is filled with an aqueous solution is available when the solution is within the The high part begins to solidify and expand, v / are developed in the actuating device, Many could damage the relatively thin wall of the bellows when the bellows is acted upon by the freezable liquid were. Any immiscible liquid such as oil can be used in the bellows as long as its solidification temperature is substantially below that of the working fluid in the 'feil 100. If oil is used, it is

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Bellows 106 arranged above the tubular part 100, as oil is lighter than water and therefore collects in the upper part of the freezer. However, if another immiscible ! Liquid is used which is heavier than water, It is contemplated that the bellows 106 may be positioned below the tubular member 100 to achieve similar results.

Because of a temperature gradient between the fluid transferring parts of the tubes 36 of the "Evaporator 3 ^Z !" The level to which the coolant temperature can drop below freezing point naturally depends on the structure of the evaporator itself and on the ambient temperature.

An ideal liquid for use in a freezer 98 would be a liquid that solidifies at the freezing point. Theoretically, its water would experience a change of state from the solid to the liquid state at the freezing point and expand in the process. However, tests carried out with distilled water have shown that it can be exposed to a much lower temperature before crystallization or solidification begins. This is illustrated in Figure 3 «From the graph it is apparent that the freezing point of the particular sample of distilled v / ater was ⁰ G at about O. However, water was exposed to temperatures such as -6.5 C in a calm environment before ice crystals formed. After the first crystal had formed, the temperature - the mass of the water and ice - rose almost instantly to about 0 °. The temperature at which ice formation begins is called the crystallization temperature and is shown in FIG.

409842/030?

represented by the left end of the bar. It can be seen that distilled water alone is not an ideal fluid Use in freezer 98 is. When the coolant temperature courtesy is offered in the evaporator, dropping to almost -6.67 ° C before the throttle valve 102 in is brought to the closed position, a lot of ice would form on the outer surface of the evaporator. With high probability the ice formation would soon prevent the air flow through the evaporator core and thus the heat transfer to the Reduce coolant significantly. This would make the icing problem even greater. In the i'ig. 5 shows the relationships which are likely to occur if only water is used in a freezer of this type would. Note the extended period of time that elapses before a frozen core thaws, and even after the freezer has frozen, and that The throttle valve closes. This is due to the reduced heat transfer explained above.

■ o ¹ -

It has been found that a mixture of a suspension of silver iodide in V has / ater a freezing temperature of about OG and a crystallization temperature in the region of about -2.22 ⁰ O has. Thus, when the coolant temperature in the evaporator falls below approximately -2.22 ⁰ C, the crystallization begins in the solution, and the freezer takes the control effect at about ⁰ ° G to by the throttle valve is moved to a more closed position and thus the temperature of the refrigerant is raised in the evaporator. It can be seen that a mixture of water and silver iodide is a beneficial fluid to fill the tube portion 100 of the freezer. The freezing characteristics of the silver iodide mixture which is used in the present embodiment is shown in FIG. The left end of the bar indicates its crystallization temperature and the right end indicates the freezing temperature. The crystallization temperature of about

409842/0302

-2.5 ° G is high enough to prevent ice accumulation To prevent outer surface of the evaporator.

Fig. 4 illustrates the operation of the "operated" throttle valve, both in operation at high and in operation at low ambient temperatures. When the air conditioner is operated at low temperatures, the Euhlmxtelt temperature drops rapidly to a value below the crystallization temperature. then Sis begins to form, and the control effect of the freezer is approximately O ⁰ G a, by bringing the throttle valve in the closed position \ v'ird. Polglich takes the coolant temperature and moves against about O ⁰ G. Because of the With fairly limited heat transfer, the coolant temperature shoots above about 0 G and the freezer reacts by opening the throttle valve further, which in turn reduces the coolant temperature. For a few cycles the freezer keeps the temperature at about ^{0 0} G.

When the air conditioner is operated at a high ambient temperature, the coolant temperature quickly drops to the crystallization ;; temperature. Because of the increased heat transfer required to cool the warm air, a longer period of time elapses before crystallization begins. The increased heat transfer further slows down the reaction of the evaporator coolant with regard to temperature changes, and thus the overshoot is less than at a low ambient temperature. As soon as crystallization begins, the control effect of the freezer also begins at around 0 G. Then the throttle valve is brought into the closed position, whereby the coolant temperature increases. If the coolant temperature ^{rises above about 0} ° C, the freezer will move the valve to a slightly more open position such that the temperature is kept at about freezing point.

4Q9842 / Q30?

Claims (3)

Patent claims 1, to continue to reduce include air conditioning system for a motor vehicle having a coolant ^ / compressor with a capacitor which is connected to the outlet of the compressor with an expansion device which is connected to the condenser to increase the pressure of the received therefrom coolant , and with an evaporator, which is connected in such a way that it takes up coolant from the expansion device and evaporates it by absorbing heat from the air flowing over the outer surfaces of the evaporator, thereby ensuring that a liquid accumulator (40 ) is provided between the evaporator (54) and the compressor (10) in order to separate vaporous refrigerant from liquid refrigerant and to supply most of the vaporous refrigerant to the compressor (10), so that the accumulator has a lower part (50) which contains liquid coolant, and has an upper part (56) that has a coolant inlet (62) and a coolant outlet (70) that wide erhin a valve seat element (80) is arranged in the interior of the accumulator (40) between the inlet and the outlet and has a passage (92) to guide coolant from the interior of the accumulator into the outlet (70), that furthermore the valve seat element (80) an elongated temperature responsive valve actuator (98) having an elongated ear member (100) connected to an axially expandable bellows (106) extending within the accumulator (40), that further includes an aqueous solution (111) is provided in the tubular part (100) which ^{freezes at a temperature of about 0} G and expands when solidified to pressurize the bellows (106) and cause it to be axially Direction extends that there is still a throttle valve (102) which is operational with the 409842/030? Vent actuating device (98) is connected and downstream from the pipe part (100) of the valve actuating device arranged and through the same with respect to the valve seat element (80) and the passage (92) therein is defeatable such that the passage of the coolant between the interior of the Accumulator and its outlet controllable in response to changes in the coolant temperature within the accumulator is. 2. Air conditioning system according to claim 1, characterized in that that an oil receiving tube (125) is provided which ■ extends from the bottom of the accumulator (40) through the valve seat element (80) extends to a point downstream of the throttle valve (102) and carries oil which collects in the accumulator, and zxtfar to the compressor when the valve element (102) is in a closed position. 3. Air conditioning system according to claim 2, characterized in that an opening (127) with a small diameter is in fluid communication with the oil pick-up pipe (125) in order to ■ control the oil flow through the oil pick-up pipe (125). 4-. Air conditioning system according to one of the preceding claims, characterized characterized in that an immiscible liquid (113) with respect to the aqueous solution (111) the interior of the bellows (106) fills and has a solidification temperature well below freezing point, thereby causing the growth of ice crystals in the aqueous solution as the coolant temperature drops below freezing point exerts pressure on the immiscible liquid and thereby the bellows in extends in the axial direction, so that the throttle valve (102) is moved. 4Q98A2 / 0302 Air conditioning system according to one of the preceding claims, characterized characterized in that the aqueous solution (111) is a saturated solution of water and silver iodide. 409842/030?