Safety system for a vehicle air conditioning system

Abstract

The invention relates to a safety system for a vehicle air conditioning system (10) which has a compressor (11) and an evaporator (12), the evaporator (12) being provided between an air supply channel (13) and an air discharge channel (14) which is designed to discharge temperature-controlled air into a vehicle interior (20). A shut-off element (15) is provided between the evaporator (12) and the air discharge channel (14), the shut-off element being connected to a controller such that the shut-off element (15) completely closes the air discharge channel (14) as a result of a sensor signal of an impact sensor and / or a refrigerant sensor, the sensor signal being received by the controller. The invention further relates to a vehicle (1) having such a safety system and to an operating method.

Description

[0001] Safety system of a vehicle air conditioning system

[0002] The invention relates to a safety system for a vehicle air conditioning system. Furthermore, the invention relates to a vehicle with such a safety system and to an operating method.

[0003] Vehicle air conditioning systems typically include a refrigerant circuit in which a refrigerant circulates. The refrigerant is compressed by a compressor and passed through an evaporator, where it evaporates and absorbs heat from the surroundings. This heated refrigerant can then release heat in a heat exchanger, which is transferred, for example, via an airflow into the vehicle interior. In this way, the vehicle interior can be heated. A reverse operation is also possible, in which heat is extracted from the vehicle interior to reduce the interior temperature.

[0004] Tetrafluoroethane, or R134a, is commonly used as a refrigerant in vehicle air conditioning systems, and it is considered harmful to the climate. To prevent climate damage from refrigerant leaks, it is now common practice to use natural refrigerants in stationary air conditioning systems. These refrigerants usually include propane, specifically R290. Such a refrigerant has several advantages. On the one hand, it is particularly efficient and offers high dynamic performance, meaning a vehicle interior can be heated very quickly from a low temperature to a high temperature, or vice versa. A disadvantage, however, is that R290 is flammable, which precludes its use in vehicle air conditioning systems because, in the event of an accident, there is an increased risk of the refrigerant leaking and creating a flammable gas mixture.In particular, risks arise if a large quantity of flammable refrigerant enters a vehicle interior.

[0005] The object of the invention is therefore to provide a safety system for a vehicle air conditioning system which prevents the inflow of flammable refrigerant into

[0006] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH The invention relates to a vehicle interior, specifically in such a way that no flammable refrigerant-air mixture forms in the vehicle interior. Furthermore, it is an object of the invention to provide a vehicle with a vehicle air conditioning system and such a safety system, as well as an operating method.

[0007] According to the invention, this problem is solved with regard to the safety system by the subject matter of claim 1, with regard to the vehicle by the subject matter of claim 9 and with regard to the operating method by the subject matter of claim 10.

[0008] Specifically, the invention is based on the concept of a safety system for a vehicle air conditioning system, wherein the vehicle air conditioning system comprises a compressor and an evaporator. The evaporator is arranged between an air supply duct and an air discharge duct, the air discharge duct being designed to deliver tempered air into a vehicle interior. A shut-off device is provided between the evaporator and the air discharge duct, which is connected to a control unit such that the shut-off device completely closes the air discharge duct as a result of a sensor signal received by the control unit from an impact sensor and / or a refrigerant sensor.

[0009] The safety system according to the invention reduces the risk of flammable refrigerant, particularly gaseous refrigerant, entering a vehicle interior. In particular, it prevents this in the event of damage to the refrigerant circuit due to an accident or impact. The safety system uses sensor signals, especially from an impact sensor and / or a refrigerant sensor. The impact sensor can, for example, detect an impact, accident, or even a vehicle rollover and proactively trigger the shut-off device. This closes the air delivery duct, preventing refrigerant from the refrigerant circuit from entering the vehicle interior. Therefore, it is preferably provided that the vehicle air conditioning system is located in an engine compartment that is, preferably hermetically, separated from the vehicle interior.In particular, the engine compartment can be divided by a partition, preferably a firewall.

[0010] 102339-WO - MSP Keller Schneider, August 8, 2025, Patentanwalts GmbH, is to be separated from the vehicle interior. The vehicle interior constitutes a passenger compartment. In other words, for the purposes of this application, the vehicle interior is defined as a space within a vehicle in which passengers or vehicle occupants are located during normal use.

[0011] It is also possible for the safety system to include a refrigerant sensor located in the vehicle interior that monitors the refrigerant concentration. If a predetermined refrigerant concentration threshold is reached, the sensor can trigger the control unit to activate the shut-off device, thus preventing further refrigerant from entering the vehicle interior. The threshold is preferably chosen to be below a critical concentration level that could lead to a deflagration or combustion within the vehicle interior.

[0012] Furthermore, the safety system may include a pressure sensor that detects the refrigerant pressure in the refrigerant circuit. This pressure sensor can be connected to the control unit in such a way that the control unit triggers the activation of the shut-off device when the pressure in the refrigerant circuit falls below a certain threshold. When the pressure drops below this threshold, it is assumed that refrigerant is escaping from the refrigerant circuit. To prevent the escaping refrigerant from entering the vehicle interior, the safety system activates and shuts off the air delivery duct.

[0013] In general, the vehicle air conditioning system equipped with the safety system according to the invention can comprise a compressor and an evaporator, wherein the compressor and the evaporator are arranged in the engine compartment. The main components, in particular the majority of the refrigerant circuit, are preferably arranged in the engine compartment, especially outside the vehicle interior. It is further preferred if the compressor and / or the evaporator are arranged as close as possible to a firewall. The critical components of the vehicle air conditioning system are thus located outside the crash zone of the vehicle.

[0014] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH vehicle ordered, thereby reducing the risk of damage to the refrigerant circuit in the event of an accident.

[0015] In a generally preferred embodiment, the compressor and evaporator are integrated into a refrigerant circuit in which a flammable refrigerant, in particular comprising propane, circulates. The use of R290 as the refrigerant is particularly preferred. Such a refrigerant exhibits high efficiency and high dynamics, which are advantageous in a vehicle air conditioning system.

[0016] Further efficiency gains are achieved by using a direct evaporator. However, direct evaporators pose a higher risk of refrigerant leakage from the vehicle's air conditioning system, particularly if it is damaged, for example, in an accident. Therefore, the safety system described here is especially relevant when the vehicle's air conditioning system uses a direct evaporator and a flammable refrigerant.

[0017] The shut-off device can be designed as a rotary valve. The rotary valve can be connected to an electric or electromechanical actuator, allowing it to be moved from an open to a closed position by means of a control signal. In the closed position, the shut-off device completely seals the air discharge duct. Alternatively, a type of gas bag can be used as the shut-off device. This type of shut-off device can incorporate an explosive or a gas generator, whereby, upon activation of the explosive or gas generator, the gas bag is filled with gas and expands within the air discharge duct, thus completely sealing it. Other shut-off devices are also possible. For example, a slide valve triggered by an explosive or an electric motor can be used to completely close the air discharge duct.

[0018] It is also preferably provided that the shut-off device, in its closed state, ensures complete fluid separation between the evaporator, in particular the refrigerant circuit, and the vehicle interior. This prevents...

[0019] 102339-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH The safety function of the safety system is particularly well suited for use. The shut-off device prevents any escaping refrigerant from entering the vehicle interior, thus preventing deflagration or combustion within the vehicle interior.

[0020] Furthermore, a heat exchanger may be installed in the air delivery duct. The heat exchanger can be integrated into the refrigerant circuit, allowing the refrigerant, which is cooled in the evaporator, to extract heat from the air supplied to the vehicle interior via the air delivery duct. In this way, the air flowing into the vehicle interior is cooled.

[0021] The air supply duct preferably has an outside air inlet and / or a recirculation duct. Fresh air or outside air can enter the air supply duct through the outside air inlet and be supplied to the vehicle interior. A fan can also be provided to draw in the air through the outside air inlet and transport it into the air supply duct. The recirculation duct, on the other hand, serves to return air from the vehicle interior to the evaporator, so that the air in the vehicle interior can be cooled again and recirculated. This creates a closed airflow system, preventing, for example, pollutants from the outside air from entering the vehicle interior. The recirculation of the vehicle interior air also makes it possible to reach the desired temperature in the vehicle interior particularly quickly.

[0022] In a preferred embodiment, a switching flap is provided in the air supply duct for switching between an outside air supply and a recirculated air supply. The switching flap thus allows the selection of whether outside air or vehicle interior air is supplied to the air supply duct. In a first position, the switching flap can close the outside air supply, thus preventing an outside air supply and allowing only a recirculated air supply. Conversely, in another position, the switching flap can close the recirculated air supply, so that only outside air enters the air supply duct.

[0023] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH also possible that the switching flap assumes intermediate positions in which a mixture of outside air and recirculated air is released into the vehicle interior.

[0024] As an alternative to a switching flap, the outside air inlet can be equipped with an outside air flap to control the outside air supply, and the recirculation duct with a recirculation flap to control the recirculation supply. Thus, instead of a single switching flap, two separate flaps can be provided to influence the supply of air to the vehicle interior.

[0025] A secondary aspect of the invention relates to a vehicle, in particular a multi-track motor vehicle, with a vehicle air conditioning system and a previously described safety system. In the vehicle according to the invention, it is preferably provided that the evaporator is arranged in an engine compartment and / or in an underbody of the vehicle. In particular, the evaporator is preferably arranged outside the vehicle interior. This reduces the risk of refrigerant flowing into the vehicle interior.

[0026] A further subordinate aspect of the invention relates to a method for operating a previously described security system. The method according to the invention preferably comprises the following steps:

[0027] - Receiving a sensor signal from an impact sensor and / or a refrigerant sensor via the control unit;

[0028] - Generating a control signal by means of the control unit and transmitting the sensor signal to the shut-off device, in particular to an actuator of the shut-off device;

[0029] - Closing of the shut-off device as a result of the control signal; and

[0030] - Closing a recirculation duct, in particular by means of a diverter flap or a recirculation flap.

[0031] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH When the recirculation duct closes, it may also be provided that an outside air vent is opened simultaneously or at least immediately afterward. This can be done, for example, via the diverter flap or the outside air flap. Opening the outside air vent has the advantage that any refrigerant that leaks, for example, in the area of ​​the evaporator, can escape into the environment or the outside air. This reduces the risk of deflagration or combustion inside the vehicle, especially within the vehicle's air conditioning system.

[0032] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying schematic figure. The single figure in this figure shows a safety system according to the invention for a vehicle air conditioning system in a vehicle, wherein the safety system is configured according to a preferred embodiment.

[0033] Specifically, the figure schematically shows a vehicle 1 comprising a passenger compartment 20 and an engine compartment 30. The passenger compartment 20 is separated from the engine compartment 30 by a firewall 31. A compressor 11 of a vehicle air conditioning system 10 is located in the engine compartment 30. The compressor 11 is fluidly connected via a refrigerant circuit 16 to a heat exchanger 17 on one side and an evaporator 12 on the other. The refrigerant circuit 16 is preferably designed as a closed circuit. A refrigerant circulates within the refrigerant circuit 16. The refrigerant is a fluid, and in the context of this application, both liquid and gaseous media are referred to as fluids.

[0034] In particular, it is planned that a propane mixture, especially R290, will be used as the refrigerant. Such a refrigerant is flammable, which is why the vehicle air conditioning system 10 includes a safety system.

[0035] The evaporator 12 is also located in the engine compartment 30. The evaporator 12 is situated in an air delivery duct 14. The heat exchanger 17 is also located in the air delivery duct 14. In the direction of airflow, which is delivered into the vehicle interior 20 via the air delivery duct 14, the

[0036] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH A blower 18 is arranged upstream of the evaporator 12. The blower 18 can draw in air via an outside air opening 13a or a recirculation duct 13b and transport it through the evaporator 12. Heat exchange takes place in the evaporator 12 between the refrigerant in the refrigerant circuit 16 and the airflow passing through the evaporator 12.

[0037] As can be seen in the figure, a shut-off device 15 is arranged in the air delivery duct 14. In the embodiment shown here, the shut-off device 15 is designed as a rotary flap. By rotating the shut-off device 15, the air delivery duct 14 can be completely closed or opened.

[0038] The recirculation duct 13b has an air inlet that opens into the vehicle interior 20. Air from the vehicle interior 20 is drawn in through the air inlet and can thus be supplied to the evaporator 12 again.

[0039] For the perspective used in the present application, the air duct connecting the evaporator 12 to the vehicle interior 20 is divided into two sections. A section of the air duct facing the vehicle interior 20, extending from the vehicle interior 20 to the shut-off device 15, is referred to as the air discharge duct. The air duct extending from the vehicle interior 20 via the evaporator 12 to the shut-off device 15, or from the outside air opening 13a to the shut-off device 15, is referred to as the air supply duct 13. The air supply duct 13 thus comprises the outside air opening 13a and the recirculation duct 13b.

[0040] A switching flap 13c can also be arranged in the air supply duct 13. The switching flap 13c can alternately close both the outside air opening 13a and the recirculation duct 13b completely. If fresh air is to enter the vehicle interior 20, the outside air opening 13a is preferably open. In this case, the switching flap 13c can be opened far enough to simultaneously close the recirculation duct 13b and thus prevent recirculation. Conversely, recirculation can be allowed while simultaneously supplying fresh air.

[0041] 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH or the supply of outside air is prevented by closing the outside air opening 13a.

[0042] In the event of an accident or impact, various sensors within the vehicle 1 are triggered. In particular, sensors used for a vehicle occupant safety system, for example to trigger seatbelt pretensioners, can also be used to activate the safety system described here. Upon receiving a sensor signal in a control unit, various control commands can be transmitted to the vehicle's air conditioning system 10. Specifically, it can be provided that if a critical sensor signal is exceeded, the shut-off device 15 is fully rotated to completely close the air outlet duct. This hermetically separates the vehicle interior 20 from the evaporator 12. The ingress of refrigerant into the vehicle interior 20 is thus effectively prevented.

[0043] The shut-off device 15 can also be fully opened, thus enabling air conditioning of the vehicle interior 20. Generally, it can be provided that a quantity of refrigerant with a mass of no more than 500 g circulates in the refrigerant circuit 16. In particular, it is preferred if the mass of the refrigerant in the refrigerant circuit 16 is no more than 350 g, more particularly no more than 250 g, and more particularly no more than 150 g. This significantly increases the safety of the vehicle air conditioning system 10.

[0044] The compressor 11 is preferably designed as a scroll compressor. Such a scroll compressor typically comprises a stationary displacement spiral and an orbiting displacement spiral that engages with the stationary displacement spiral, and is characterized in particular by high durability and maintenance-free operation.

[0045] 102339-WO - MSP Keller Schneider

[0046] August 8, 2025 Patent Attorneys GmbH Reference List

[0047] I vehicle

[0048] 10 Vehicle air conditioning

[0049] II Compressor 12 Evaporator

[0050] 13 Air supply duct

[0051] 13a Outside air opening

[0052] 13b Recirculation duct

[0053] 13c Diverter valve 14 Air discharge duct

[0054] 15 Shut-off device

[0055] 16 Refrigerant circuit

[0056] 17 heat exchangers

[0057] 20 Vehicle interior 30 Engine compartment

[0058] 31 Splash guard

[0059] 102339-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

Claims

Patent claims 1. Safety system of a vehicle air conditioning system (10) comprising a compressor (11) and an evaporator (12) which is a direct evaporator, wherein the evaporator (12) is arranged between an air supply duct (13) and an air discharge duct (14) which is designed to discharge tempered air into a vehicle interior (20), wherein a shut-off device (15) is provided between the evaporator (12) and the air discharge duct (14) which is connected to a control unit such that the shut-off device (15) completely closes the air discharge duct (14) as a result of a sensor signal received by the control unit from an impact sensor and / or a refrigerant sensor.

2. Safety system according to claim 1 characterized in that the compressor (11) and the evaporator (12) are integrated into a refrigerant circuit (16) in which a flammable refrigerant, in particular comprising propane, circulates.

3. Safety system according to one of the preceding claims characterized in that the shut-off device (15) is designed as a rotary flap.

4. Safety system according to one of the preceding claims characterized in that the shut-off device (15) in the closed state causes a complete fluid separation between the evaporator (12), in particular the refrigerant circuit (16), and the vehicle interior (20).

5. Safety system according to one of the preceding claims characterized in that a heat exchanger (17) is arranged in the air delivery duct (14). 102339-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH 6. Safety system according to one of the preceding claims characterized in that the air supply duct (13) has an outside air opening (13a) and / or a recirculation duct (13b).

7. Safety system according to claim 6 characterized in that a switching flap (13c) for switching between an outside air supply and a recirculated air supply is arranged in the air supply duct (13).

8. Safety system according to claim 6 characterized in that the outside air opening (13a) has an outside air flap for controlling the outside air supply and the recirculation duct (13b) has a recirculation flap for controlling a recirculation supply.

9. Vehicle (1), in particular a multi-track motor vehicle, with a vehicle air conditioning system (10) and a safety system according to one of the preceding claims, wherein the evaporator (12) is arranged in an engine compartment (30) or in an underbody of the vehicle (1).

10. Method for operating a security system according to any of the preceding claims, comprising the following steps: - Receiving a sensor signal from an impact sensor and / or a refrigerant sensor via the control unit; - Generating a control signal by means of the control unit and transmitting the sensor signal to the shut-off device (15), in particular to an actuator of the shut-off device (15); Closing of the shut-off device (15) as a result of the control signal; and 102339-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH - Closing a recirculation duct (13b), in particular by means of a diverter flap (13c) or a recirculation flap. 102339-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

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