DE10227660B3 - Vehicle air conditioning system and method for operating such a system - Google Patents

Abstract

The vehicle air conditioning system comprises a brine circuit, a cooling circuit for removing thermal energy from the brine circuit, a heating circuit for supplying thermal energy into the brine circuit, at least one consumer heat exchanger to be arranged on a vehicle interior, which can be coupled to the brine circuit, and a control device for controlling the the brine circuit to the at least one consumer heat exchanger per unit of thermal energy supplied. In order to avoid the so-called fog flash effect in a cost-effective manner in such a vehicle air conditioning system on the consumer heat exchanger, condensate deposited on the consumer heat exchanger can be evaporated in a targeted manner during a drying phase by the control device being adapted to ensure that the pro Unit of time supplied heat energy can control accordingly.

Description

background the invention

The invention relates to a vehicle air conditioning system with a brine circuit, a cooling circuit for lead away of thermal energy from the brine circuit, a heating circuit for supplying thermal energy in the brine circuit, at least one on a vehicle interior consumer heat exchanger to be arranged, which can be coupled to the brine circuit, and a control device for Control the at least one consumer heat exchanger with the brine circuit supplied per unit of time Amount of heat energy. The invention further relates to a vehicle, in particular a bus, which is provided with such a vehicle air conditioning system, and a method for operating such a vehicle air conditioner.

A generic vehicle air conditioning system and a corresponding method of operation are out DE 198 24 516 A1 such as DE 199 37 949 A1 known. There, a device and a method for heating and / or cooling a vehicle interior, in particular an interior of a bus, are described. The device is provided with a cooling circuit comprising at least one refrigeration generator, a heating circuit comprising at least one heat generator, and at least one consumer circuit with at least one consumer heat exchanger, the heat transfer medium of which can be brought into flow connection with the cooling and / or heating circuit. The device is characterized by a central circuit free of consumers, which can be fed from the cooling and / or heating circuit, the consumer circuit being able to be fed from the central circuit and having a control element which is designed or adjustable, a volume flow taken from the central circuit to control heat transfer medium. The central circuit therefore forms a brine circuit that can be coupled with the individual consumer circuits. With the help of a control device in the form of a distributor valve, the brine circuit can be supplied with targeted heat transfer medium from the cooling circuit and / or the heat circuit. Switching between heating mode and cooling mode is possible by using the distributor valve to conduct the appropriately tempered heat transfer medium from the heating circuit and / or the cooling circuit through the brine circuit.

When switching from cooling mode heating often results in fogging of windows on the vehicle interior. Cause of this So-called "fog flash" is the fact that yourself during of cooling operation on the consumer heat exchanger Has deposited condensed water, which is caused by switching supplied warm Heat transfer medium is suddenly evaporated.

Sudden fogging of the Slices can be restricted Lead view and under certain circumstances adversely affect driving safety. With the sudden Evaporation of the condensed water also increases the relative humidity in the vehicle interior, which leads to a loss of comfort.

The devices according to DE 198 24 516 A1 such as DE 199 37 949 A1 are also equipped with a so-called reheat circuit, which can be connected to the heating circuit bypassing the central circuit.

The reheat cycle can on the one hand used to dehumidify the air inside the vehicle to support. To do this, the air is first heat exchangers of the consumer circuit connected to the central circuit cooled until the air is below the dew point and the air humidity as Condensate accumulates, which is derived. The cooled air is then over the heat exchangers the rehabilitation cycle to a desired one Temperature level warmed up, increasing the relative humidity lowers the air. About that the reheat cycle also allows an air conditioning zone assigned to it stronger in the vehicle to heat than it is the temperature level of the heat transfer medium in the central circuit would allow or even the air conditioning zone assigned to the reheat cycle to heat directly from the heating circuit, while one or all other air conditioning zones via the consumer heat exchanger connected to the central circuit chilled become.

So it becomes the vehicle interior thereby supplying dried air, by cooling them specifically and subsequently the condensate is drained off. Condensate, which on the relatively large surface of the Consumer heat exchanger has deposited itself, however, cannot be derived in this way become. It leads to the fog flash described above.

Out DE 198 12 171 C1 a motor vehicle air conditioning system with a compressor is known in which the refrigerant circuit is passed directly through a consumer heat exchanger without a brine circuit. In order to reduce the risk of fog flash, the refrigerant circuit is set to maximum cooling capacity and the dried, cooled air is reheated on a reheat heater. Only after the reheat operation is it gradually switched to the mode of operation that is actually desired. It is controlled by coupling and uncoupling a compressor in the refrigerant circuit. Here too, the condensate separated from the air to be dried must be drained off as completely as possible at the consumer heat exchanger.

Out DE 195 12 356 C1 it is known that in a motor vehicle air conditioning system without a brine circuit, in addition to setting the maximum cooling capacity, it is also possible to use a delayed switch-on of a fan for drying air on a consumer heat exchanger.

The invention is based on the object Vehicle with a vehicle air conditioning system mentioned at the beginning the fog flash effect on the consumer heat exchanger on inexpensive Way is safely avoided.

Solution according to the invention

This task is according to the invention with a Solved at the beginning of the vehicle air conditioning system, in which the control device for a targeted evaporation of the consumer heat exchanger condensed water during a drying phase is designed such that the per unit time supplied Thermal energy while the drying phase is controllable. Furthermore, the task with one Vehicle solved, in which such a vehicle air conditioning system is installed, as well as with a method for operating such a vehicle air conditioning system according to the invention, with the step: targeted evaporation of the consumer heat exchanger condensed water during a drying phase, by controlling the during the drying phase Consumers heat exchanger supplied per unit of time Amount of heat energy.

In the vehicle air conditioner according to the invention is targeted during a drying phase just so much heat energy supplied to the consumer heat exchanger that the condensate evaporates to a limited extent. The amount of heat energy supplied is determined by the temperature, the volume flow and the heat capacity of the the consumer heat exchanger funded usually liquid Heat transfer medium determined. According to the invention is advantageous in particular the temperature of the heat transfer medium is controlled while Volume flow is kept constant.

In other words, in the method according to the invention Just as much condensate per unit of time at the consumer heat exchanger evaporates that there is no fog flash. The limit for the pro Unit of time supplied Amount of heat energy could for different embodiments the vehicle air conditioning system according to the invention can be determined by calculation and / or by tests.

In the vehicle air conditioner according to the invention will also during the drying phase the consumer heat exchanger Thermal energy fed. About that In addition, the control of the amount of thermal energy required in the Brine circuit no connection and disconnection of a condenser of the refrigerant circuit. The control is therefore particularly cost-effective and precise.

advantageous Developments of the invention

The vehicle air conditioning system according to the invention enables in particular a relatively fast one and effective evaporation of condensate on the consumer heat exchanger, by adapting the control device to operate during the Drying phase is the amount of thermal energy supplied to the consumer heat exchanger per unit of time increase can.

The amount of thermal energy is increased in particular advantageous in that the control device is adapted so that them during of the entire drying phase of the consumer heat exchanger supplied per unit of time Amount of heat energy increase substantially linearly can. The linear increase leads to, that the temperature of the consumer heat exchanger flowing through Air and its ability to deal with air humidity record, is increased to such an extent as per unit time Condensate on the consumer heat exchanger evaporated. Alternatively, a non-linear increase can be chosen, for example a logarithmic, exponential or step-like increase, which to a reinforced one Evaporation leads at the end of the drying phase.

The control of the Thermal energy supply is advantageously coupled with at least one reheat heat exchanger, which is assigned to the at least one consumer heat exchanger. The Control device is adapted so that it is during the drying phase which the reheat heat exchanger pro Unit of time supplied Amount of heat energy control according to the amount of thermal energy supplied to the consumer heat exchanger per unit of time can. In total, you can the consumer heat exchanger and the reheat heat exchanger the air flowing through the vehicle air conditioner as required heat. That through the reheat heat exchanger to be fed per unit of time Amount of heat energy is compared to known vehicle air conditioners, where with a maximum cooling capacity is worked, relatively low.

The heat energy requirement for the reheat heat exchanger preferably to keep it low, the control device is advantageously adapted to the fact that them during the drying phase, the amount of thermal energy supplied to the reheat heat exchanger per unit of time can decrease.

The control device is also advantageously adapted to the deer during the entire drying phase at-heat exchangers per unit time can essentially reduce the amount of thermal energy supplied. Such a reduction in the supply of heat can be implemented in a simple manner in terms of control technology and, together with the control of the supply of heat at the consumer heat exchanger, leads to the desired temperature increase in the vehicle interior.

Another advantageous Further development of the vehicle air conditioning system according to the invention an outside temperature sensor is provided, which is operationally coupled to the control device, and the Control device can be fed Amount of heat energy dependent on that determined by the outside temperature sensor outside temperature Taxes. This training is based on the knowledge that the outside air on the vehicle, which is sucked into the vehicle air conditioning, in unfavorable Case has a relative humidity of 100%. This fact will according to the invention at a Definition of a maximum amount of condensate to be evaporated by the consumer heat exchanger considered. The receptivity humidity depends on the temperature of the outside air. According to the invention, the temperature the outside air taken into account when determining the amount of condensate to be evaporated the amount of condensate evaporated per unit of time can be close to a maximum allowable Value led without a fog flash.

In addition, it is advantageous that a blow-out temperature sensor to determine the blow-out temperature of the consumer heat exchanger brimmed Heat transfer medium provided is and the control device is adapted to the pro Unit of time supplied Amount of heat energy in dependence the outside temperature can control such that the blow-out temperature over a certain period of time maintains a substantially constant value. This further education stands in contrast to known vehicle air conditioning systems, in which the Consumers heat exchanger amount of heat energy supplied dependent on has been determined by the temperature of the liquid heat carrier flowing in it. The blow-out temperature to be controlled depends on the outside temperature fixed to the vehicle air conditioner.

By setting the blow-out temperature from the consumer heat exchanger evaporated a defined amount of condensate and thereby an excessive relative Humidity of the escaping Prevents air. The blow-out temperature is over a certain period of time kept constant, which means during this period the consumer heat exchanger a constant maximum amount of water per unit of time (measured in g / kg dry air) is evaporated.

One happens particularly advantageously such evaporation of the condensate from the consumer heat exchanger on the entire drying phase.

The control device can be advantageous the discharge temperature depending the outside temperature to a value of about 15 ° C up to 25 ° C, preferably from 18 ° C up to 22 ° C Taxes.

It is also advantageous if the Control device is adapted to the amount of thermal energy supplied via a Period of about 10 to 80 minutes, preferably from about 30 to 60 Minutes depending that determined by the outside temperature sensor outside temperature can control.

The above temperature and Fair values are based on an averaged temperature Consumer heat exchanger set in a particular operating cycle of a vehicle air conditioner Service. They are particularly suitable to be used in other operating cycles ensure a safe evaporation of the total amount of condensate from the consumer heat exchanger. The Above temperature and time values may also be dependent from a temperature of a heat carrier in Consumer heat exchanger set become. For the case that the temperature of the heat transfer medium is still too low to the desired Can reach blow-out temperature at the consumer heat exchanger with extended fair values and / or reduced temperature values are worked. alternative or additionally can they Time and / or temperature values can be redefined if one sufficient temperature of the heat transfer medium, for example with a temperature sensor on the cooling circuit of the vehicle's internal combustion engine.

Furthermore, a control device be provided, the incorrect operation of the vehicle air conditioning prevented in an "anti-fog" operating mode. The control device determines that the required according to the invention Minimum discharge temperature through manual operation exceeded but cannot fall below. The control device can alternatively or additionally a minimum fan speed for one Air conveyor provide through the air as a heat transfer medium the consumer heat exchanger can be conveyed into an interior of the vehicle. Exceeding the Fan speed however, is allowed. This can reduce the air flow through the consumer heat exchanger, the drying of the consumer heat exchanger and measurement results the discharge temperature sensor would be avoided become.

The in the training according to the invention provided minimum blow-out temperature leads alongside the advantages mentioned above for preheating the panes of a Vehicle, especially the inside of the windscreen.

Summary the drawing

An exemplary embodiment of a inventive method to operate a vehicle air conditioning system using the attached schematic Drawing closer explained. It shows:

1 a diagram of the temperature profile of a heat transfer medium at the flow of a consumer heat exchanger of a vehicle air conditioning system according to the invention during a drying phase.

detailed Description of the embodiment

The method according to the invention is advantageous with a vehicle air conditioner for heating and / or cooling one Vehicle interior on a motor vehicle, not shown performed in the form of an omnibus.

The vehicle air conditioner has one Heating circuit with a flow on that of heat generators with a warm Heat transfer medium can be supplied. As a heat generator a drive motor, a retarder and / or an additional heater are provided.

The flow of the heating circuit leads to a mixing point, from which a flow of a central circuit branches off. In the central cycle a pump and a distribution valve are arranged.

The distribution valve is a 3-way valve designed on the next to the return of the central circuit also a return of the heating circuit and a rewind a cooling circuit are connected.

There is a heat exchanger in the cooling circuit arranged, the flow of the cooling circuit upstream is. The flow is connected to the mixing point. The cooling circuit, the heating circuit and the central circuit together form one Brine circuit.

With this brine cycle is on Heat exchanger a refrigerant cycle coupled, in which a compressor, a capacitor, a choke and one in the heat exchanger arranged evaporator are connected in series.

There are three in the central circuit Consumer circuits involved. A preliminary run branches in each of these consumer circuits from the flow of the central circuit. In the consumer cycles is One pump each, the heat transfer medium can each promote a consumer heat exchanger. The consumer heat exchangers are in a front area, a floor area and a roof area arranged of the motor vehicle.

In the flow direction behind the consumer heat exchangers a distributor valve is connected, each as a 3-way valve is designed and to which a return line is connected. The returns are each with the return of the central circuit. It depends on the distribution valves also a return line connected which back to the preliminaries in the direction of flow before the pumps of the consumer circuits.

The consumer heat exchangers each have a reheat heat exchanger assigned to which an adjustable throttle is connected upstream. The Reheat heat exchanger are directly connected to the heating circuit.

With the circuit arrangement designed in this way, the following heating and / or cooling functions can be carried out:
First, as with conventional devices, the heat transfer medium heated via the heating circuit can be provided at the mixing point, while the heat transfer medium cooled via the heat exchanger of the cooling circuit can be provided at the mixing point. Depending on the heating or cooling requirements, the heat transfer medium can be pumped into the consumer circuits. The associated pumps are operated and the distribution valves switched as required.

To take part in the consumer cycles To provide the reheat function, heated heat transfer medium can be conveyed to the reheat heat exchangers. The distribution of the heat carrier flow promoted in this way to those arranged in the reheat circuits Reheat heat exchanger done with the help of under certain circumstances remote-controlled chokes.

To control the distribution valves and a control device is provided for the chokes.

In 1 it is illustrated how the temperature in the flow of the central circuit can be set in such a way with the help of the control device. According to the invention, the condensation water deposited on the consumer heat exchanger is evaporated during a drying phase by controlling the amount of thermal energy supplied to the consumer heat exchanger per unit of time accordingly.

The drying phase extends over the period of the time units 2 to 10 , During this period, the amount of thermal energy supplied per unit of time is increased such that the temperature in the lead is increased from a temperature unit 10 to a temperature unit of approximately 26. The increase in particular takes place essentially linearly during the entire period of the drying phase.

As the temperature at the flow of the central circuit is increased, the amount of thermal energy supplied to a reheat heat exchanger per unit of time is adjusted in accordance with the amount of heat energy supplied to the associated consumer heat exchanger per unit of time during the drying phase. The amount of thermal energy supplied to the reheat heat exchanger per unit of time is reduced during the drying phase, in particular essentially linearly during the entire period of the drying phase Ringert.

The method according to the invention (see 1 "New") stands in contrast to conventional methods, in which the temperature in the flow of the central circuit or the brine circuit has been increased substantially by leaps and bounds (see 1 , "Original").

As an alternative to targeted control the temperature of the heat transfer medium in the central circuit and a subsequent supply of the tempered Heat transfer medium into one or more consumer circuits, can also directly Temperature can be controlled in a consumer circuit. In particular Is it possible there the temperature is targeted at a consumer heat exchanger to increase without this directly affecting the rest of the consumer heat exchangers concerns. The targeted controlled increase is possible by using the central circuit just as much warm heat transfer medium is branched off into the respective consumer circuit will, as for the one desired in the consumer cycle Temperature is required. The one to be branched off from the central circuit Amount of warm heat transfer medium can be arranged with the help of an adjustable on the consumer circuit Throttle or a distribution valve can be controlled.

In this case, it is targeted in one initially cooled Controlled consumer heat exchanger just so much warm heat transfer medium fed from the heated central circuit, such as for vaporizing Condensate on the consumer heat exchanger possible is without a fog flash on windows on the vehicle interior.

So with the help of the central circuit for example a soil consumer cycle already fed with high heating output from the central circuit be while for one The consumer circuit on a windscreen of the vehicle delays warmth Heat transfer medium is removed from the heating circuit. This can be done on the windscreen in this case, existing heating deficit by heating with the help the associated Reheat cycle to be balanced.

Alternatively to that in 1 illustrated mode of operation of a vehicle air conditioning system according to the invention, this can be provided with an outside temperature sensor, which is operatively coupled to the control device.

The control device is with this Vehicle air conditioner set up to supply the amount of thermal energy supplied dependent on that determined by the outside temperature sensor outside temperature controls. With the outside temperature sensor, for example an outside temperature from something higher than 11 ° C determined. At this outside temperature can either cold or warm heat transfer medium from the central circuit through a consumer heat exchanger, e.g. the consumer heat exchanger on a windscreen of the vehicle.

The consumer heat exchanger supplied per unit of time Amount of heat energy becomes dependent the outside temperature certainly. This approach is based on the knowledge that the outside temperature can have at most one relative air humidity. Furthermore, the receptivity the outside air, which is subsequently promoted by the consumer heat exchanger, depending on their temperature. So it can be the maximum per based on the outside temperature Unit of time with the outside air introduced Humidity can be determined. Based on this, the additional evaporation can of condensate from the consumer heat exchanger.

With the vehicle air conditioning system designed in this way is also a blow-out temperature sensor for determining the blow-out temperature by the consumer heat exchanger brimmed Air provided as a heat transfer medium and the control device is adapted to do that per unit time supplied Amount of heat energy dependent on the outside temperature controls such that the blow-out temperature over a certain period of time maintains a substantially constant value. The constant discharge temperature is determined in such a way that the blown air has a maximum permissible relative Humidity does not exceed.

The control device maintains the blow-out temperature essentially about the entire drying phase constant at a value of about 15 ° C to 25 ° C, preferred of 18 ° C up to 22 ° C. The period for the drying phase is about 10 to 80 minutes, preferably about 30 to 60 minutes. The period becomes dependent that determined by the outside temperature sensor outside temperature controlled.

In the type according to the invention the control is only a very small amount of additional heating required because relatively much Thermal energy over the Central heating circuit supplied can be. In particular, according to the invention, the cooling circuit does not have to be at maximum cooling capacity operated while is heated at the same time.

Claims (23)

Vehicle air conditioning system with - a brine circuit, - a cooling circuit for removing thermal energy from the brine circuit, - a heating circuit for supplying thermal energy into the brine circuit, - at least one consumer heat exchanger to be arranged on a vehicle interior, which can be coupled to the brine circuit, and - a control device for controlling the amount of thermal energy supplied to the at least one consumer heat exchanger per unit time with the brine circuit, characterized in that the control device leads to a targeted Ver Evaporation of condensate deposited on the consumer heat exchanger during a drying phase is designed such that the thermal energy supplied per unit of time can be controlled during the drying phase. Vehicle air conditioning system according to claim 1, characterized in that the control device is adapted to operate during the Drying phase is the amount of thermal energy supplied to the consumer heat exchanger per unit of time increase can. Vehicle air conditioning system according to claim 1 or 2, characterized in that that the control device is adapted to operate during the entire period of the drying phase, the amount of thermal energy supplied to the consumer heat exchanger per unit of time increase substantially linearly can. Vehicle air conditioning system according to one of claims 1 to 3, characterized in that at least one reheat heat exchanger is provided, the at least one consumer heat exchanger is assigned, and the control device is adapted so that them during the drying phase, the amount of thermal energy supplied to the reheat heat exchanger per unit of time corresponding to that of the consumer heat exchanger supplied per unit of time Amount of heat energy can control. Vehicle air conditioning system according to claim 4, characterized in that the control device is adapted to operate during the Drying phase of the reheat heat exchanger supplied per unit of time Amount of heat energy can decrease. Vehicle air conditioning system according to claim 4 or 5, characterized in that that the control device is adapted to operate during the entire period of the drying phase, the amount of thermal energy supplied to the reheat heat exchanger per unit of time can decrease substantially linearly. Vehicle air conditioning system according to one of claims 1 to 6, characterized in that - on Outside temperature sensor provided which is operationally coupled to the control device, and - the control device the fed Amount of heat energy dependent on that determined by the outside temperature sensor outside temperature can control. Vehicle air conditioning system according to claim 7, characterized in that - on Ausblastemperaturfühler to determine the blow-out temperature of the consumer heat exchanger brimmed Heat transfer medium is provided and - the Control device is adapted so that it is per unit time amount of heat energy supplied in dependence the outside temperature can control such that the blow-out temperature over a certain period of time maintains a substantially constant value. Vehicle air conditioning system according to claim 8, characterized in that the control device is set up so that the blow-out temperature over the entire drying phase is kept essentially constant. Vehicle air conditioning system according to claim 8 or 9, characterized in that that the control device depends on the blow-out temperature the outside temperature to a value of about 15 ° C up to 25 ° C, preferably from 18 ° C up to 22 ° C can control. Vehicle air conditioning system according to one of claims 7 to 10, characterized in that that the control device is adapted so that it supplies the amount of thermal energy supplied Period of about 10 to 80 minutes, preferably from about 30 to 60 Minutes, depending that determined by the outside temperature sensor Control outside temperature can. Vehicle with a vehicle air conditioning system according to one of claims 1 to 11th Method for operating a vehicle air conditioning system according to a of claims 1 to 11, characterized by the step: Targeted evaporation from at the consumer heat exchanger condensed water deposited during a Drying phase, by controlling the during the drying phase Consumers heat exchanger supplied per unit of time Amount of heat energy. A method according to claim 13, characterized by the step: Increase by of the consumer heat exchanger pro Unit of time fed Amount of heat energy during the Drying phase. A method according to claim 13 or 14, characterized by the Step: Essentially linear increase from that of the consumer heat exchanger supplied per unit of time Amount of heat energy while the entire period of the drying phase. Method according to one of Claims 13 to 15, characterized by the step: controlling the amount of thermal energy supplied to a reheat heat exchanger per unit of time in accordance with that of the consumer heat exchanger amount of thermal energy supplied per unit of time during the drying phase. A method according to claim 16, characterized by the step: Reduce of which the reheat heat exchanger pro Unit of time fed Amount of heat energy during the Drying phase. A method according to claim 16 or 17, characterized by the Step: Essentially linearly decreasing from that of the reheat heat exchanger supplied per unit of time Amount of heat energy while the entire period of the drying phase. Method according to one of the claims 13 to 18, characterized by the step: Control the amount of heat energy supplied dependent on the outside temperature on the vehicle air conditioner. A method according to claim 19, characterized by the step: Taxes the consumer heat exchanger supplied per unit of time Amount of heat energy while the drying phase in such a way that the discharge temperature from the Consumers heat exchanger blown out heat transfer medium during a given Maintains a substantially constant value during the period. A method according to claim 20, characterized by the step: keeping constant the discharge temperature during the entire drying phase. A method according to claim 20 or 21, characterized by the Step: Controlling the discharge temperature depending on the outside temperature to a value of about 15 ° C up to 25 ° C, preferably from 18 ° C up to 22 ° C. Method according to one of claims 19 to 22, characterized through the step: Control the amount of heat energy supplied via a Period of about 10 to 80 minutes, preferably from about 30 to 60 Minutes depending that determined by the outside temperature sensor Outside temperature.