DE102007031073A1 - Air-conditioner for motor vehicle, comprises accumulator, which is found behind evaporator and another accumulator, behind condenser for collecting liquid refrigerant - Google Patents

Abstract

The air-conditioner (7) comprises an accumulator (8), which is found behind an evaporator (5) and another accumulator (18), behind a condenser (2) for collecting liquid refrigerant (6). One of the accumulators has a desiccant (19,20). The latter accumulator takes a smaller volume than the former accumulator. An independent claim is also included for a method for cooling air with an air conditioner for motor vehicle.

Description

The The invention relates to an air conditioner for a motor vehicle, for example a car and a motor vehicle with this air conditioner.

Automotive air conditioners are based on a refrigerant circuit in which a refrigerant is alternately expanded and compressed. A well-known refrigerant circuit, as in 1 shown next to the compressor 1 a capacitor 2 , an accumulator or collector 3 for collecting liquid refrigerant, an expansion organ 4 and an evaporator 5 , The components mentioned are connected to each other in the order mentioned and in fluid supply and form the said refrigerant circuit. The flow direction of the refrigerant 6 is indicated by the arrow P.

The Compressing the refrigerant This is done with the compressor, which is adjustable in performance. The power regulation This can be done by operating the stroke volume of the compressor is adjusted, for. B. by a swash plate compressor with variable Stroke volume is used. Another possibility is a Constant displacement compressor, for example a swash plate type compressor, not consistent to drive mechanically. Because the compressor is powered by a belt drive the crankshaft is driven, this is the compressor in an intermittent operation by an electrical coupling decoupled from the belt drive or coupled to the belt drive.

The expansion element is usually adjustable and adjusts the correct pressure and temperature for the refrigerant in the refrigerant circuit at the evaporator outlet. For example, in a swash plate compressor with a fixed displacement volume behind the evaporator, a high superheat must be set so that only vaporous refrigerant arrives at the downstream compressor, since otherwise the compressor is damaged. If, on the other hand, a swash plate compressor with variable displacement is used, it must be ensured that only slight overheating is provided behind the evaporator or at the evaporator outlet, in order to avoid the so-called _" hunting", under which a temperature oscillation perceivable by the vehicle occupant and perceived as unpleasant is understood at the evaporator and at the outlet nozzles.

Out the above statements that turns out to be dependent of the chosen Compressor model adapted the expansion organ, d. H. differently adjusted, must be by z. As a high or low overheating is set. A "slight" overheating should in the context of this Representation as a temperature up to a maximum of 3 K, preferably up to a maximum 2K above the boiling temperature of the refrigerant whereas a "high" overheating about that goes.

The Expansion unit is part of the HVAC module: heating, ventilation and air conditioning modules). Come for the product range one Automotive company already for other reasons a plurality of example n (n is an integer) Air conditioners for the n air conditioners of the various Vehicle models used, so the optional use of 2 compressor types for a total of 2 · n air conditioners to be used. release and validation effort for the air conditioners of the auto company are rising due to the above adjustment problem considerably.

It is an object of an embodiment of the Invention, a car air conditioner whose expansion organ does not respond to the respective Model of the chosen Compressor must be adjusted.

Especially the task is to train the vehicle air conditioner so that at the optional use of a variable or fixed compressor Stroke volume no adjustment of the expansion device is required.

The solution This object is achieved by the features of the independent claims. advantageous Developments and other embodiments result dealing with the characteristics of dependent Claims.

One The first aspect of the invention relates to an air conditioner for a motor vehicle, in the refrigerant circuit behind a vaporizer a first accumulator and behind a Capacitor a second accumulator to collect liquid refrigerant.

First, be noted that the term "behind" the evaporator / capacitor on the flow direction of the refrigerant or on the way of the refrigerant in the refrigerant circuit refers. The term "behind" the evaporator / condenser is in the sense of "am Evaporator output "or" at the capacitor output "to understand.

A refrigerant circuit comprises first of all, and also in this invention, a series connection of a compressor, a condenser, an expansion element and an evaporator in the order mentioned. In contrast to a known refrigerant circuit, as in the 1 is shown, the refrigerant circuit according to the invention thus has two accumulators.

at the said embodiment The first accumulator, which would be called "accumulator" in English, is on the suction side of the refrigerant circuit, in front of the compressor, ie at the compressor inlet. It serves to liquid refrigerant Keep away from the compressor and thus carry out a phase separation, wherein its outlet-side opening Ö in the Gas phase is located. The second accumulator, which would be called "receiver" in English, is located in the high-pressure line between the condenser and the expansion element. Its outlet side opening is located Ö yourself in the liquid phase

at Proper adjustment of the expansion device can in this embodiment two compressor types, in particular a compressor with fixed or with variable displacement, can be used optionally. this happens in that with the expansion organ a single parameter set with respect to pressure and temperature is set behind the evaporator, for both Compressor types is suitable. In the example of the optional use a swash plate compressor with fixed or variable displacement This happens by the fact that with the expansion organ to the mentioned A small overheating is set at the evaporator outlet, so that in combination with the first accumulator the operation of both Types of swash plate compressors is possible. An adaptation or Adjustment of the expansion device to the respective compressor type is not required.

Of the Use of a first accumulator in the suction line behind the Evaporator allows it thus, without adjustments of the expansion organ two different Choose compressor types freely, so that the total number of air conditioners used in the automobile company drops, in the example by the factor 2. Correspondingly decreases the effort for in-house validation and approval of air conditioners can do more Common parts are used and decreases the number of used Service parts. Also, the cost of manufacturing is reduced.

As stated above, is the TXV or the expansion device to the pressure and temperature of the refrigerant adjust behind the evaporator. For this purpose, a controllable expansion organ, usually an expansion valve, to be used. This one owns a measuring top usually arranged at the top for measuring pressure. In the Messdom there is a refrigerant, which in principle can be identical to that of the refrigerant circuit or different from this. The choice of refrigerant, which is mostly a secret of the TXV manufacturer, affects the opening characteristics of the expansion organ.

at Compressors with fixed displacement become the same in the refrigerant circuit refrigerant used as in said Messdom (parallel loading or English: parallel charge). For compressors with variable displacement or externally controlled compressors, another refrigerant is chosen (a other load or English: cross charge). With the mentioned embodiment the invention it is possible this is different for compressors with fixed displacement Provide loading (cross charge).

In a second embodiment either one of the first and second accumulators has a desiccant.

The Desiccant ensures in a known manner that the refrigerant Water is withdrawn. It is sufficient if only one the accumulators has a drying agent, so that the relevant Accumulator is simpler and cheaper. has an accumulator no desiccant, so it can be made smaller as with a desiccant, indicating the placement of the accumulator relieved, since the space for The arrangement of the various components in the vehicle always very is tight. Since either the first or the second accumulator can be provided with a drying agent, arises in terms the arrangement of the components a greater freedom.

In a third embodiment the second accumulator occupies a smaller volume than the first one Accumulator.

This is feasible by adding a first accumulator with a desiccant chooses, so for the second accumulator none is required. The second accumulator is typically located together with the condenser in the engine compartment at the very front of the radiator. Falls specifically the second accumulator is small, so is the probability his damage lower in a frontal impact. This offers the potential for lower Repair costs, about it for one better TIC classification (traffic insurance classification) and thus if necessary for a cheaper one Insurance policy at least in Germany legally prescribed car insurance.

In a further embodiment includes the refrigerant circuit of the air conditioner Furthermore, a compressor and an expansion device, acting as a compressor optionally a compressor with fixed or variable displacement is provided, and wherein the expansion device is designed in the refrigerant line provide a slight overheating behind the evaporator.

You choose a slight overheating behind the evaporator in the suction line, so it would be the prior art when using a compressor with a fixed Stroke volume the considerable probability that the compressor trying to compress liquid refrigerant. Furthermore would be the Compressor louder. By arranged in the suction line first Accumulator you can afford it, yet a slight overheating provided because the first accumulator protects the compressor from liquid droplets. You choose a compressor with variable displacement, so guaranteed a slight overheating behind the evaporator, that no hunting occurs.

As in the introductory part of the description, should be a little overheating as an overheating up to a maximum of 3 K, preferably up to a maximum of 2 K above the boiling point of refrigerant whereas high overheating goes beyond that.

When Compressor can be a swash plate compressor with fixed or variable Stroke volume selected become. With a fixed stroke volume, the power control is intermittently via a suitable coupling and uncoupling to or from the mechanical (belt) drive, d. H. the internal combustion engine of the vehicle. The coupling and uncoupling done by an electrical coupling.

to warranty a slight overheating behind the evaporator can be proceeded so that in the refrigerant path behind the evaporator the pressure and the temperature of the refrigerant be measured. The measured values are then transmitted via a measuring line Control unit supplied to the the valve position of the designed as a controllable or controllable valve Expansion organ controls or regulates.

One second aspect of the invention relates to a motor vehicle with a air conditioning according to one of the embodiments described above.

One third aspect of the invention relates to a method for cooling Air with a car air conditioner, their refrigerant circuit including a condenser and a compressor with fixed Stroke volume includes. In the process, the air to be cooled passed or passed through the condenser, in the refrigerant line a slight overheating is set behind an evaporator and there liquid refrigerant retained especially one first accumulator.

The Method controls or regulates pressure and temperature of the refrigerant behind the evaporator to a slight overheating of, for example maximum 3K. As a result, the compressor more liquid droplets are supplied as in the prior art, resulting in the subsequent retention the same, for example, by the first accumulator, is compensated. Incidentally, will in terms of the resulting benefits to the above directed.

Further Features and advantages of the claimed invention will be apparent from the following detailed description with reference to the accompanying drawings recognizable, which are given below as non-limiting examples are. Here, the use of reference numerals in the figures not to be understood that the reference numerals denote To limit the scope of the claimed invention. Show it:

1 schematically the structure of an air conditioner according to the prior art;

2 an embodiment of an air conditioner according to the invention,

3 a motor vehicle with an air conditioner according to 2 ,

In the figures, which generally denote like objects with like reference numerals, shows 2 schematically an embodiment of an air conditioner 7 according to the invention. The air conditioner 7 has an evaporator 5 , a first accumulator 8th , a compressor 1 , a capacitor 2 and an organ of expansion 4 in the form of a valve 9 , The valve 9 is adjustable and ensures that only vaporous refrigerant 6 to the compressor 1 arrives. The valve position is made dependent on which temperature T and which pressure p the refrigerant 6 between evaporator 5 and compressor 1 Has. These parameters are transmitted via the test lead 10 certainly. The arrow P indicates the flow direction of the refrigerant, which may be R134a (tetrafluoroethane).

The compressor 1 has a constant displacement and is driven by a belt drive 11 powered, in turn, by an internal combustion engine 12 of the motor vehicle 13 , see. 3 , is driven. The belt drive 11 comes with an electric clutch 14 intermittently with the compressor 1 connected.

In the operation of the air conditioner 7 Air L generated by a blower, not shown, flows through the evaporator 5 through to the vehicle interior 15 ,

In the refrigerant line 16 flows refrigerant 6 in the direction of arrow P from the valve 9 out over the evaporator 5 to the first accumulator 8th , Not one shown control circuit determined via the measuring line 10 the pressure p and the temperature T behind the evaporator 5 , The valve position is regulated depending on these measured values so that behind the evaporator 5 or at its output a slight overheating of a maximum of 3 K above the boiling point of the refrigerant 6 given is.

After the evaporator 5 flows from the measuring point M from substantially vapor refrigerant 6 in the direction of arrow P on, but still has a certain amount of liquid droplets. Success of this refrigerant 6 following to the compressor 1 , this would have negative consequences in terms of noise and durability. Because of this, is located in the refrigerant line 16 between the evaporator 5 and the compressor 1 the first accumulator 8th , He performs a phase separation, so that the subsequently arranged compressor 1 no harm.

In the first accumulator 8th forms during operation a sump liquid refrigerant 6 out. Below its liquid level is located in a lower area of the refrigerant line 16 a hole 17 , Through this hole 17 Ensures that even a small and controllable amount of liquid refrigerant 6 to the compressor 1 passes that carries refrigerant oil for lubrication purposes.

In the described operation, instead of the compressor with fixed displacement and a compressor with variable displacement can be used. For example, a variable displacement swash plate type compressor may be used instead of a fixed displacement swash plate type compressor. In this case, the clutch 14 between the internal combustion engine 12 and the compressor 1 omitted, since it is then always driven and internally regulates its performance. Structural and with regard to its setting is in this embodiment, not shown, the valve 9 unchanged, that is, an adaptation of the valve 9 on the supercharger model is not required. This can with the air conditioner 7 either a compressor with fixed or variable displacement can be used, making the air conditioner 7 not changed.

Become both the first accumulator 8th as well as the second accumulator 18 used, so you can at the first accumulator 8th or the second accumulator 18 on the drying agent 19 respectively. 20 without. In this case one of the accumulators falls 8th . 18 smaller, which leads to a greater freedom in the arrangement of the automotive components in the design of a new vehicle.

If you specifically choose the second accumulator 18 without a drying agent 20 and makes it structurally smaller than the first accumulator 8th , it should be noted that the capacitor 2 and the second accumulator 18 are placed in the engine compartment at the front next to the radiator. In this case, the probability of damaging the second accumulator 18 in a head-on collision smaller, and also the associated repair costs. In Germany this may lead to a better classification of damage classes in the motor insurance policy.

Even though above specific embodiments The person skilled in the art will recognize that the description these embodiments does not have the purpose to limit the invention in the form specified. The Rather, the invention is intended to cover all modifications, equivalents and alternatives which fall within the scope of the claimed invention.

1

compressor

2

capacitor

3

accumulator

4

expansion element

5

Evaporator

6

refrigerant

7

air conditioning

8th

first accumulator

9

Valve

10

Measurement line

11

belt drive

12

internal combustion engine

13

motor vehicle

14

clutch

15

Automotive interior

16

Refrigerant line

17

drilling

18

second accumulator

19

desiccant

20

desiccant

P

arrow

L

air

Ö

opening

Claims (10)

Air conditioner ( 7 ) for a motor vehicle ( 13 ), in whose refrigerant circuit behind an evaporator ( 5 ) a first accumulator ( 8th ) and behind a capacitor ( 2 ) a second accumulator ( 18 ) for collecting liquid refrigerant ( 6 ) are located. Air conditioner according to claim 1, in which either the first or the second accumulator comprises a desiccant ( 19 . 20 ) owns. air conditioning according to one of the preceding claims, in which the second accumulator occupies a smaller volume than the first accumulator. Air conditioner according to one of the preceding claims, whose refrigerant circuit is a compressor ( 1 ) and an expansion organ ( 4 ), wherein as the compressor optionally a compressor with fixed or variable displacement is provided and the expansion device is designed to provide a slight overheating in the refrigerant line at the evaporator outlet. air conditioning according to claim 4, the expansion device designed st, an overheating of a maximum of 3 Kelvin and in particular a maximum of 2 Kelvin. air conditioning according to one of the preceding claims, in which as compressor a swash plate compressor with fixed or variable displacement is provided. Motor vehicle ( 13 ), comprising an air conditioner ( 7 ) according to one of the preceding claims. Method for cooling air with an air conditioner ( 7 ) for motor vehicles, comprising the following steps: a) collecting liquid refrigerant ( 6 ) in the refrigerant circuit after the evaporator ( 5 ), b) collecting liquid refrigerant ( 6 ) in the refrigerant circuit after the condenser ( 2 ). Method according to claim 8, wherein a controlled Evaporation of refrigerant takes place and behind the evaporator, a slight overheating is set. The method of claim 9, wherein at the evaporator exit an overheating of a maximum of 3 Kelvin is set.