DE10259827B3 - Cooling system for automobile has cooling medium fed between 2 cooling circuits via venturi jet device for obtaining reduced pressure in one cooling circuit - Google Patents

Abstract

The cooling system has at least 2 cooling circuits (10,14), each provided with a respective evaporator (12,16), with a compressor (18) contained in a common circuit arm (20) between the cooling circuits. A device (22) provided with a venturi jet allows the cooling medium to flow from one cooling circuit to the other via the compressor, for obtaining a reduced pressure in one cooling circuit during their simultaneous operation.

Description

The invention relates to a system for cooling, especially for a vehicle with at least one first refrigeration circuit with at least one first evaporator, at least one second refrigeration circuit with at least one second evaporator and at least one compressor operating in at least one of the at least one first cooling circuit and the at least one a second refrigeration cycle common branch is arranged.

Such cooling systems with two or more cooling circuits are known. They are used, for example, to cool various areas the interior of a commercial vehicle. For example, the first refrigeration cycle for cooling of the front area in the cab, while the second cooling circuit for cooling of the lying area is used. Here is the refrigeration circuit for cooling the front area in the cab, in particular with a so-called Climate box or HVAC ("Heat Ventilation Air Condition ") fitted.

Frequently is desired that the two of the refrigeration circles assigned evaporators perform tasks that are different Underlying temperature requirements. For example, can be provided be the first evaporator in a climate box with an air flow is acted upon while the second evaporator to generate cold in a latent storage is provided. The latter is therefore preferably a lower one Evaporation temperature work as the air flow evaporator in the climate box. You can also lower evaporation temperatures associated with cooling one Freezer truck he wishes his.

Because of this different Tasks so far have required the two related cooling circuits operate alternately and this through a complex solenoid valve system to control. For example, loading the latent memory is preferred then take place when the first one is connected to the climate box cooling circuit is uncoupled.

A disadvantage of such solutions is that the provision of solenoid valves and components for their Control is associated with high effort; defects can continue occur on solenoids, control etc. Furthermore, be Safety risks with normally closed valves, as it is at Power failure can result in both circuits being blocked.

The invention is based on the object cooling system to disposal to provide, which overcomes the disadvantages of the prior art and especially an inexpensive one and safe solution for the operation of two cooling circuits with different requirements.

The DE 198 60 057 A1 and the DE 198 38 880 A1 show examples of air conditioning systems with a primary circuit and a secondary circuit.

This task comes with the characteristics of the independent Claim solved.

Advantageous embodiments of the invention are in the dependent claims specified.

The invention builds on the generic system characterized in that a device is provided with at least one Venturi nozzle is about the the at least one compressor refrigerant from the at least a first refrigeration cycle and can be supplied to the at least one second refrigeration circuit, so while the simultaneous operation of both cooling circuits in the minimum a second refrigeration cycle a lower pressure can be generated than in the at least one first refrigeration cycle. In this way, the continuous operation of both cooling circuits allows the under different evaporation temperatures in the two Evaporating the refrigeration circuits by providing different pressures in the refrigeration circuits he follows. These different pressures are used of the Venturi principle which says that in the case of a pipe with a constriction, being the transition is shaped so that the cross-sectional change of the flow is as possible without vortex formation, a lower one in the area of the narrowing There is pressure in front of and behind the pipe. This negative pressure can be now take advantage of in one of the refrigeration circuits generate a lower pressure than in the other refrigeration cycle and thus in the refrigeration cycle lower pressure to allow a lower evaporation temperature.

The invention is designed in a particularly advantageous manner so that the device with the at least one Venturi nozzle has two input connections and one output connection, wherein a first input connection is supplied with refrigerant from the first refrigeration circuit, which essentially flows axially through the at least one Venturi nozzle, and a second input connection Refrigerant is supplied from the second refrigeration circuit, which flows laterally into areas of low pressure of the at least one Venturi nozzle, and the refrigerant of the two refrigeration circuits is fed to the compressor together via the outlet connection. The device can thus be installed in the manner of a T-piece in the cooling system comprising two cooling circuits, and in particular existing cooling systems which comprise a T-piece for coupling the cooling circuits in front of the compressor can be further developed to the cooling system according to the invention in a simple and cost-effective manner , there only the T-piece has to be replaced by the device providing the Venturi effect. The refrigerant from the first refrigeration cycle flows essentially axially through the Venturi nozzle and experiences the known pressure loss in the area of the constriction. If the refrigerant flow of the second refrigeration circuit is supplied in this area, this results in a pressure reduction in the second refrigeration circuit and thus a corresponding reduction in the evaporation temperature.

Can also be useful Be provided that the device with the at least one venturi has a plurality of axially arranged Venturi nozzles, which the refrigerant from the second cooling circuit via one Distribution feedable is. So lets yourself about a system with Venturi nozzles connected in series Efficiency of pressure reductions based on the Venturi effect increase.

The system is more advantageous Way designed so that the pressure within the at least one venturi is less than the suction pressure of the compressor. In this way receives one the additional Suction effect to reduce pressure in the second cooling circuit.

The cooling system according to the invention is particularly advantageous Formed further in that in the flow direction behind the compressor Condenser in the first cooling circuit and the second refrigeration cycle common branch is arranged. So the same capacitor in a known manner for both cooling circuits used, which further minimizes the number of components in the system becomes.

The cooling system according to the invention is preferably designed so that the evaporation temperature in the second Evaporator is less than in the first evaporator, in particular the first evaporator with an evaporation temperature greater than 0 ° C works and the second evaporator with an evaporation temperature lower than 0 ° C is working. That way you can different cooling tasks are perceived at which the evaporation temperatures Requirements on the one hand a temperature above freezing of water and, on the other hand, below the freezing point of water be put.

In this context, it is particularly useful that the first evaporator in an air conditioner, especially a parking cooler of a vehicle, is arranged and with a to be cooled Air flow is applied. Because the first vaporizer is preferred works at an evaporation temperature above 0 ° C, is at the application the evaporator with a stream of air no fear of icing.

It is also particularly useful that the second evaporator is arranged in a latent storage. The cold storage can therefore due to the low evaporation temperature in the second evaporator done with high efficiency.

It can also be advantageous that the second evaporator for cooling a loading space of a commercial vehicle is provided. Here too are low Evaporation temperatures he required, for example for transportation of food.

The invention is based on the knowledge underlying that a cooling system with two connected cooling circuits continuously and without great effort on solenoid valves and the like Control can be operated. This is achieved in that in the two cooling circuits using the Venturi effect different pressures disposal be put. So you can different evaporation temperatures in the evaporators at the same time are present, so different tasks through the evaporator Fulfills can be.

The invention will now be referenced on the accompanying drawings based on preferred embodiments exemplified.

It shows:

1 a schematic diagram for explaining a system according to the invention; and

2 a first embodiment of a device for providing the Venturi effect.

In the following detailed Description of the drawings designate the same reference numerals or comparable components.

1 shows a schematic diagram for explaining a system according to the invention. The system shown comprises a first refrigeration circuit 10 with a first evaporator 12 in an air conditioner 36 is arranged. The air conditioner 36 can be arranged, for example, in the form of a so-called front box, climate box or HVAC in the front area of a vehicle, in particular a commercial vehicle. Inside the air conditioner 36 can next to the evaporator 12 further heat exchangers 38 be provided, for example those that are connected to a heating circuit of the vehicle. Also in the air conditioner 36 a blower 40 arranged that the first evaporator 12 and if necessary the further heat exchangers 38 charged with an air flow that is ultimately used for cooling and possibly also for heating a vehicle interior.

There is also a compressor in the first cooling circuit 18 and the compressor 18 downstream capacitor 34 intended. Before the first vaporizer 12 is a first expansion organ 42 arranged. Next to the first refrigeration cycle 10 is a second refrigeration cycle 14 provided that with the first refrigeration cycle 10 over two branches 44 . 46 communicates. In this way, the first refrigeration cycle share 10 and the second refrigeration cycle 14 a common branch 20 in which the compressor 18 and the capacitor 34 are arranged. In the second refrigeration cycle 14 is a second evaporator 16 arranged, the circulating refrigerant from the condenser 34 via a solenoid valve 48 and an expansion organ 50 is fed. The one from the second evaporator 16 escaping coolant must have a check valve 52 happen before branching out again 44 can reach. The solenoid valve 48 and the check valve 42 are only required if the second evaporator 16 is used to generate cold in a latent storage.

According to the invention it is now provided that at the branch 44 An institution 22 is arranged with a Venturi nozzle. This facility 22 is subsequently related to 2 explained in more detail.

2 shows a first embodiment of a device for providing the Venturi effect. The facility 22 includes a venturi nozzle 24 or a Venturi tube that extends through a narrowed area 32 related to the direction of flow from the inlet port 26 to the output connection 30 distinguished. The Venturi nozzle shown 24 is symmetrical in its cross-sectional shape, but this is not necessary. Rather, a large variety of cross-sectional profiles can be realized and adapted to the corresponding requirements. The connections 26 . 30 the Venturi nozzle can preferably have a circular cross section, but can also be designed in a different way.

The coolant now flows into the inlet connection 26 the Venturi nozzle 24 with a pressure p ₁ , it experiences due to the fluid mechanics of the Venturi nozzle 24 to the narrowed area 32 towards a pressure reduction to a pressure p ₂ ; when flowing out of the Venturi nozzle 24 from the output connection 30 then there is again an increased pressure p ₃ , so that the following applies in total:
P ₁ > P ₂ <P ₃

One now leads in the facility 22 the Venturi nozzle 24 another stream of coolant on the side 28 in that area 32 with reduced pressure, so that at the input port 28 connected refrigerant circuit can be operated at a lower pressure than that at the inlet connection 26 connected cooling circuit. With correct design of the Venturi nozzle 24 the pressure provided for the second cooling circuit can be lower than the suction pressure at the outlet side of the device 22 arranged compressor.

To explain some exemplary operating modes of the cooling system according to the invention, reference is now made to 1 Referred. This is based on the example that the evaporator 16 in the second refrigeration cycle 14 serves to load a latent memory, which is to be understood without restricting the generality of the present invention, because of the second evaporator 16 Any cooling tasks can be performed for which a low evaporation temperature is advantageous. It is essential for the operation of the system that the first refrigeration circuit 10 and the second refrigeration cycle 14 can be operated simultaneously, although different pressures in the cooling circuits 10 . 14 to provide. This is the success of deploying a facility 22 with a venturi nozzle 24 in front of the compressor 18 , with a pressure reduction in the second refrigeration circuit in the manner according to the invention 14 he will be enough. There is therefore no need for complex shading of the system with solenoid valves, as was the case with systems of the prior art. Due to the different cooling requirements, the evaporator could only use one of the cooling circuits 10 . 14 be operated as intended, because otherwise, due to the inevitable pressure equalization, no very different evaporation temperatures could have been achieved in the evaporators.

When the latent storage is unloaded, that is to say in particular when the parking cooler is operating, or when the system is at a standstill, the magnetic valve is preferably activated 48 in front of the expansion organ 50 before the entrance of the second evaporator 16 closed to prevent the coolant from shifting. The solenoid valve 48 otherwise it can always remain open.

For example, a cooling system according to the invention with a refrigerant volume flow of 1 l / s with a pressure of 3 bar in front of the Venturi nozzle 24 and a pressure of 1.9 bar in the Venturi nozzle 24 operated, the compressor suction pressure is 2.8 bar. In this way, for example, an evaporation temperature in the first evaporator of 0.7 ° C and an evaporation temperature in the storage evaporator of -11 ° C can be achieved.

The invention leads to a cost reduction especially with a parking cooler by saving Solenoid valves. This results in considerable savings in the dimensioning and design of the refrigerant lines before first evaporator and still with regard to control the system, since the compressor is not controlled by the parking cooler control more has to be done. The Venturi nozzle let yourself integrate in a simple way, since only the already existing Tee must be replaced by the appropriate facility.

The in the description above, in the drawings and in the claims disclosed features of Invention can both individually and in any combination for the realization the invention be essential.

10

first cooling circuit

12

first Evaporator

14

second cooling circuit

16

second Evaporator

18

compressor

20

common branch

22

Facility with venturi nozzle

24

venturi

26

input port

28

input port

30

output port

32

constricted Area

34

capacitor

36

air conditioning

38

Further heat exchangers

40

fan

42

expansion element

44

branch

46

branch

48

magnetic valve

50

expansion element

52

check valve

Claims (9)

System for cooling, in particular for a vehicle, with - at least one first cooling circuit ( 10 ) with at least one first evaporator ( 12 ), - at least one second cooling circuit ( 14 ) with at least one second evaporator ( 16 ) and - at least one compressor ( 18 ) in at least one of the at least one first cooling circuit ( 10 ) and the at least one second cooling circuit ( 12 ) common branch ( 20 ) is arranged, characterized in that a device ( 22 ) with at least one Venturi nozzle ( 24 ) is provided, via which the at least one compressor ( 18 ) Refrigerant from the at least one first cooling circuit ( 10 ) and the at least one second cooling circuit ( 14 ) can be supplied so that during the simultaneous operation of both cooling circuits ( 10 . 14 ) in the at least one second cooling circuit ( 14 ) a lower pressure can be generated than in the at least one first cooling circuit ( 10 ). System according to claim 1, characterized in that the device ( 22 ) with the at least one Venturi nozzle ( 24 ) two input ports ( 26 . 28 ) and an output connector ( 30 ), whereby - a first input connection ( 26 ) Refrigerant from the first refrigeration cycle ( 10 ) is supplied, which the at least one Venturi nozzle ( 24 ) flows essentially axially, - a second input connection ( 28 ) Refrigerant from the second refrigeration circuit ( 14 ) is fed into areas ( 32 ) low pressure of the at least one Venturi nozzle ( 24 ) flows in, and - the refrigerant of the two cooling circuits ( 10 . 14 ) together via the output connection ( 30 ) the compressor ( 18 ) is supplied. System according to claim 1 or 2, characterized in that that the device with the at least one Venturi nozzle several has axially arranged Venturi nozzles to which the refrigerant from the second cooling circuit via one Distribution feedable is. System according to one of the preceding claims, characterized in that the pressure within the at least one Venturi nozzle ( 24 ) is lower than the suction pressure of the compressor ( 18 ). System according to one of the preceding claims, characterized in that in the flow direction behind the compressor ( 18 ) a capacitor ( 34 ) in the first cooling circuit ( 10 ) and the second cooling circuit ( 14 ) common branch ( 20 ) is arranged. System according to one of the preceding claims, characterized in that the evaporation temperature in the second evaporator ( 16 ) is lower than in the first evaporator ( 12 ), in particular - the first evaporator ( 12 ) works with an evaporation temperature greater than 0 ° C and - the second evaporator ( 16 ) works with an evaporation temperature lower than 0 ° C. System according to one of the preceding claims, characterized in that the first evaporator ( 12 ) in an air conditioner ( 36 ), in particular a parking cooler of a vehicle, is arranged and subjected to an air flow to be cooled. System according to one of the preceding claims, characterized in that the second evaporator ( 16 ) is arranged in a latent memory. System according to one of the preceding claims, characterized in that the second evaporator ( 16 ) is provided for cooling a cargo space of a commercial vehicle.