Safety system of a refrigerant circuit of a motor vehicle

Abstract

The invention relates to a safety system of a refrigerant circuit (10) of a motor vehicle, in particular a motor vehicle air conditioning system, comprising at least one shut-off member (11) for cutting-off the refrigerant circuit (10) in a gas-tight manner, wherein the shut-off member (11) is configured to cut-off the refrigerant circuit (10) in a gas-tight manner in the event of an impact of the motor vehicle. The invention also relates to a method for controlling such a safety system.

Description

[0001] Safety system of a refrigerant circuit in a motor vehicle

[0002] The invention relates to a safety system of a refrigerant circuit of a vehicle and a control system for such a safety system.

[0003] The increasing electrification of vehicles presents new challenges for the air conditioning of passenger compartments. Air conditioning systems typically consist of a compressor, an expansion valve, an evaporator, and a condenser. These components are connected via fluid lines, in which a refrigerant circulates. Air conditioning systems using tetrafluoroethane or R134a as refrigerants have proven particularly efficient. However, such refrigerants are no longer desirable in vehicle air conditioning systems because accidents, in particular, pose an increased risk of these climate-damaging refrigerants escaping into the environment.

[0004] Natural refrigerants such as propane or R290 are therefore often used in stationary air conditioning systems. These refrigerants are functionally well-suited because they exhibit high dynamic properties, meaning that the desired comfort temperature within an air-conditioned room can be reached quickly. However, suitable natural refrigerants are flammable, which is why their use in mobile applications is considered critical. Regulatory requirements therefore stipulate that only a limited volume of flammable refrigerant may be used in a vehicle air conditioning system.

[0005] Current vehicle air conditioning systems are often fully direct or semi-direct. A fully direct air conditioning system uses a single refrigerant for the entire air conditioning circuit. In other words, the refrigerant compressed by the compressor is fed directly to an evaporator, which is thermally coupled to the supply air flowing into the passenger compartment. The supply air is thus cooled directly via the evaporator, with the flammable refrigerant absorbing heat.

[0006] 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH and evaporates. The refrigerant is then fed directly to a condenser, for example, a cooler, in which the heated refrigerant is cooled again. In a semi-direct air conditioning system, at least one sub-circuit, in particular the sub-circuit that includes the evaporator, is operated with a single refrigerant. A different refrigerant can be used for another sub-circuit, for example, the condenser. The two sub-circuits are coupled to each other via heat exchangers.

[0007] While so-called compact air conditioning systems are also known, in which the compressor circuit is separate and connected via heat exchangers to an air conditioning circuit facing the passenger compartment and a radiator circuit facing the radiator, different refrigerants can circulate in the various sub-circuits. For example, a flammable refrigerant can be used in the compressor circuit, as the quantity of flammable refrigerant is small due to the small size of the compressor circuit. The other two sub-circuits, particularly the radiator circuit and the air conditioning circuit, can be equipped with a non-flammable refrigerant.

[0008] However, it has been shown that fully direct or semi-direct air conditioning systems exhibit higher efficiency and improved dynamics. A disadvantage, however, is the relatively large amount of refrigerant used. This poses particular risks when, for climate protection reasons, naturally occurring, flammable refrigerants are used. It is critical if such flammable refrigerants enter the passenger compartment or vehicle interior. Such a refrigerant leak can be caused by an accident, which, due to the nature of the accident, further endangers the vehicle occupants.

[0009] Therefore, the object of the present invention is to provide a safety system for a refrigerant circuit of a motor vehicle, in particular a motor vehicle air conditioning system, which reduces the risk to vehicle occupants from flammable refrigerant. Furthermore, it is an object of the invention to provide a control method for such a safety system.

[0010] 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH According to the invention, this task is accomplished with regard to the security system by the

[0011] Features of claim 1 and with regard to the control method are solved by the features of claim 11.

[0012] In particular, the problem is solved by a safety system for a refrigerant circuit of a motor vehicle, especially a motor vehicle air conditioning system, with at least one shut-off device for gas-tight isolation of the refrigerant circuit. The shut-off device is configured to gas-tightly isolate the refrigerant circuit in the event of a collision with the motor vehicle.

[0013] The basic idea of ​​the invention is therefore to ensure, by means of a shut-off device, that the refrigerant does not escape completely into the passenger compartment in the event of an accident or impact of the vehicle. For this purpose, the refrigerant circuit is gas-tightly separated by the shut-off device in the event of an impact, so that at most only a fraction of the refrigerant can enter the passenger compartment. The position of the shut-off device within the refrigerant circuit is preferably selected such that the amount of refrigerant that may enter the vehicle interior is so small that it poses no risk of deflagration or fire.

[0014] As an additional safety device, at least one refrigerant sensor can be provided to continuously measure the refrigerant concentration in the passenger compartment of the vehicle. This allows the refrigerant circuit to be shut off even if the vehicle does not experience an impact. The refrigerant sensor detects the refrigerant concentration in the passenger compartment and triggers the shut-off device as soon as a predetermined threshold is exceeded. This threshold is preferably selected such that the shut-off device is triggered when the refrigerant concentration in the passenger compartment is still at a non-critical level, i.e., so low that a deflagration and / or fire is unlikely or preferably impossible. However, the trigger threshold is preferably selected such that

[0015] 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH the risk of a deflagration or fire exists if the refrigerant concentration continues to increase.

[0016] The shut-off device can be mechanically self-actuated. In particular, the shut-off device can be designed so that it is mechanically triggered upon impact of the vehicle and gas-tightly isolates the refrigerant circuit.

[0017] Alternatively, the shut-off device can have an electric drive for actively isolating the refrigerant circuit. The electric drive can be triggered by a control unit connected to a corresponding crash sensor in the vehicle. Various crash sensors can be used. It is particularly preferred if the shut-off device is coupled via the control unit to crash sensors of a vehicle occupant safety system, which are also used to trigger seat belt tensioners and airbags.

[0018] Furthermore, the shut-off device may be designed to contain an explosive charge and be arranged and configured so that the refrigerant circuit is ruptured upon impact of the vehicle. In this respect, the shut-off device can function similarly to the gas generator of an airbag, with the internal explosive charge causing the refrigerant circuit to be disrupted in such a way that it closes at the desired point. The explosive charge can act directly on the refrigerant circuit or on the refrigerant circuit's pipes or hoses.

[0019] It is also possible that shut-off devices are provided, which are triggered by the explosive charge. Such shut-off devices could be, for example, corresponding gate valves or valves. It is also conceivable that a hose in the refrigerant circuit is melted at a predetermined point by means of an explosive charge, with the melting occurring in such a way that the hose is sealed off. Triggering the shut-off device with an explosive ensures a particularly rapid disconnection of the refrigerant circuit.

[0020] 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH In a preferred embodiment of the safety system according to the invention, at least one impact sensor is provided for detecting an impact of the motor vehicle. The safety system may have independent impact sensors. It is also possible that the safety system is coupled with a vehicle occupant safety system that includes airbags and / or seat belt tensioners, so that the impact sensors of the vehicle occupant safety system are also used in the safety system described here to trigger the shut-off device.

[0021] In particular, the impact sensor and the shut-off device, preferably the electrical actuator of the shut-off device, can be coupled to a control unit such that the shut-off device can be actively actuated in the event of a vehicle impact to disconnect the refrigerant circuit. The control unit can therefore receive the signal from an impact sensor and generate a corresponding control signal to the shut-off device when the impact sensor provides values ​​indicating a vehicle impact. The control signal can be transmitted to the shut-off device to cause it to close or disconnect the refrigerant circuit. The control unit can be integrated into a control unit of an occupant safety system, in particular an airbag control unit or a seatbelt pretensioner control unit.

[0022] The shut-off device may also include an overpressure safety device. Such a device allows refrigerant to be released in a controlled manner if there is overpressure in the refrigerant circuit. This prevents hazards emanating from the refrigerant circuit itself. In the event of a vehicle collision, there is a risk of fire or other overheating, which can lead to a pressure increase in the refrigerant circuit. The overpressure safety device is useful for reducing this resulting overpressure and thus mitigating additional hazards emanating from the refrigerant circuit, especially from a disconnected refrigerant circuit. However, this does not preclude the overpressure safety device from being active even when the refrigerant circuit is in operation. Therefore, the overpressure safety device is not limited to activation only in the event of or after a collision.

[0023] 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH to relieve overpressure in motor vehicles, but can release any overpressure that may arise during the operational use of the refrigerant circuit.

[0024] Generally, the refrigerant circuit can be designed to include a compressor, a refrigerant reservoir, a condenser, and an evaporator, with the shut-off device located directly before or immediately after the compressor in the refrigerant circuit. These positions of the shut-off device are advantageous for minimizing the amount of refrigerant that might escape towards a passenger compartment.

[0025] It is particularly preferred if several shut-off devices are provided, wherein at least one first shut-off device is arranged between the condenser and the compressor, at least one second shut-off device between the compressor and the evaporator, and / or at least one third shut-off device is arranged between the evaporator and the condenser. This does not preclude the inclusion of further shut-off devices. For example, a third shut-off device may be provided between the compressor and the evaporator. The second shut-off device may be arranged upstream of a refrigerant reservoir and the third shut-off device downstream of a refrigerant reservoir. It is also possible for two shut-off devices to be arranged between the evaporator and the condenser, for example, the third shut-off device near the evaporator and a fourth shut-off device near the condenser.The shut-off devices can be triggered simultaneously if a vehicle impact is detected or if the refrigerant concentration in a passenger compartment exceeds a threshold. However, it is also possible to trigger the shut-off devices individually, depending on the sensor data. For example, if the refrigerant concentration in the passenger compartment increases, it may be ensured that only the shut-off devices closest to the evaporator, in particular the third and fourth shut-off devices, are activated.

[0026] A secondary aspect of the invention relates to a method for controlling a safety system of a refrigerant circuit of a motor vehicle, in particular a

[0027] 102337-WO - MSP Keller Schneider, August 8, 2025, Patentanwalts GmbH, regarding the security system described above. The procedure preferably comprises the following steps:

[0028] Detection of a vehicle impact using at least one impact sensor and / or detection of a refrigerant concentration in a passenger compartment exceeding a predetermined threshold using at least one refrigerant sensor and / or detection of a pressure drop in the refrigerant circuit using a pressure sensor;

[0029] Generation of a disconnect signal in a control unit connected to the at least one impact sensor and / or the at least one refrigerant sensor and / or the pressure sensor;

[0030] Transmitting the disconnect signal to a shut-off device, in particular a drive or explosive device of a shut-off device, for actuating the shut-off device; and

[0031] - Separation of the refrigerant circuit by actuating the shut-off device and switching off a compressor of the refrigerant circuit.

[0032] The procedure described here further enhances the safety of a motor vehicle. Particularly when using flammable refrigerants, it prevents the build-up of a refrigerant concentration within the passenger compartment that could lead to a deflagration or combustion. In the event of a collision or upon receiving relevant sensor data, the refrigerant circuit is instead gas-tightly disconnected at predetermined points by actuating the shut-off device. Furthermore, the compressor of the refrigerant circuit is switched off to prevent any further pressure build-up in the disconnected circuit.

[0033] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying schematic drawing. The single figure in the drawing shows a circuit diagram of a safety system according to the invention, based on a preferred embodiment.

[0034] 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH The safety system shown in the figure is part of a refrigerant circuit 10 of a motor vehicle. Such a refrigerant circuit 10 serves for air conditioning, in particular for cooling the air supplied to the passenger compartment in order to set a suitable comfort temperature in the passenger compartment.

[0035] The refrigerant circuit 10 comprises a compressor 12, which can, for example, be a scroll compressor. The compressor 12 is coupled via a fluid line to a refrigerant reservoir 13, which is located downstream of the compressor 12 in the direction of refrigerant flow. Downstream of the refrigerant reservoir 13, in the direction of refrigerant flow, is an evaporator 15, which exchanges heat with an airflow supplied to the passenger compartment. In the evaporator 15, the refrigerant absorbs heat from the air flowing into the passenger compartment, thereby cooling the air flowing into the passenger compartment and simultaneously evaporating the refrigerant in the evaporator 15. The evaporated refrigerant then enters an expansion valve 16, where it expands and is supplied via another fluid line to a condenser 14. The condenser 14 can, for example, be a radiator of the vehicle.In the condenser 14, the refrigerant is cooled down and returns to the compressor 12 via another fluid line, where the refrigerant is compressed again and fed to the refrigerant tank 13.

[0036] In the illustrated embodiment, the safety system of the refrigerant circuit 10 comprises several shut-off devices 11. Each shut-off device is coupled to vehicle sensors via a control unit. In particular, there is a signal connection to impact sensors that detect a vehicle impact. For the purposes of this application, an impact is also understood to mean a rollover or other accident involving the vehicle that results in damage to the vehicle and poses a potential risk of refrigerant leakage. The shut-off devices 11 can also be signal-coupled to a refrigerant sensor in the passenger compartment.

[0037] 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH In principle, a single shut-off device 11 is sufficient to form the safety system according to the invention. The shut-off devices 11 shown in the figure essentially represent the preferred separation points at which, in the event of an impact or other triggering situation of the safety system, the refrigerant circuit 10 is disconnected. A first shut-off device 11a is provided directly in the return line from the condenser 14 to the compressor 12. The first shut-off device 11a is preferably located in a front area of ​​a vehicle, in particular in the front area of ​​an engine compartment near the radiator grille or the headlights. A further, second shut-off device 11b can additionally or alternatively be arranged between the compressor 12 and the refrigerant tank 13.

[0038] It is also preferred if, additionally or alternatively, the evaporator 15 can be completely separated from the refrigerant circuit 10. For this purpose, at least one shut-off device 11, in particular a fourth shut-off device 11d, can be provided, located between the refrigerant reservoir 13 and the evaporator 15. However, it is preferred if two shut-off devices 11 are provided, which separate the evaporator 15 from the refrigerant circuit 10. A third shut-off device 11c can be located between the expansion valve 16 and the condenser 14, whereas the fourth shut-off valve 11d is arranged between the refrigerant reservoir 13 and the evaporator 15. In this way, the evaporator 15 and the expansion valve 16 can be completely separated from the refrigerant circuit 10 by the third shut-off device 11c and the fourth shut-off device 11d.

[0039] Similarly, the condenser 14 should preferably be completely separable from the refrigerant circuit 10. If desired, a fifth shut-off device 11e can be provided, as shown in the figure, located directly in the inflow to the condenser 14. The condenser 14 can then be completely separable from the refrigerant circuit 10 via the first shut-off device 11a and the fifth shut-off device 11e.

[0040] 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH The invention generally provides that the shut-off devices 11 are arranged such that the maximum amount of refrigerant that can escape in the event of damage to the refrigerant circuit 10 is reduced to a maximum of 100 g. A flammable refrigerant, in particular propane or R290, is preferably used as the refrigerant in the refrigerant circuit 10 described here. Such a refrigerant has particularly high efficiency and offers good dynamics for achieving rapid air conditioning of a passenger compartment.

[0041] 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH Reference List

[0042] 10 Refrigerant circuit

[0043] 11 Shut-off device

[0044] 11a first shut-off device 11b second shut-off device

[0045] 11 c third shut-off device

[0046] 11d fourth shut-off device

[0047] 11 e fifth shut-off device

[0048] 12 Compressor 13 Refrigerant tank

[0049] 14 Capacitor

[0050] 15 evaporators

[0051] 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

Claims

Patent claims 1. Safety system of a refrigerant circuit (10) of a motor vehicle, in particular of a motor vehicle air conditioning system, comprising at least one shut-off device (11) for gas-tight separation of the refrigerant circuit (10), wherein the shut-off device (11) is configured to gas-tightly separate the refrigerant circuit (10) in the event of an impact of the motor vehicle.

2. Safety system according to claim 1 characterized in that at least one refrigerant sensor is arranged for the continuous measurement of a refrigerant concentration in a passenger compartment of the motor vehicle.

3. Safety system according to claim 1 or 2 characterized in that the shut-off device (11) is mechanically self-actuating.

4. Safety system according to claim 1 or 2 characterized in that the shut-off device (11) has an electric drive for actively disconnecting the refrigerant circuit.

5. Safety system according to claim 1 or 2 characterized in that the shut-off device (11) has an explosive and is arranged and configured such that the refrigerant circuit (10) is closed by explosives upon impact of the motor vehicle.

6. Safety system according to one of the preceding claims characterized in that at least one impact sensor is provided for detecting an impact of the motor vehicle. 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH 7. Safety system according to claim 6 characterized in that the impact sensor and the shut-off device (11), in particular the electric drive of the shut-off device (11), are coupled to a control unit in such a way that the shut-off device (11) can be actively actuated in the event of an impact of the motor vehicle in order to disconnect the refrigerant circuit (10).

8. Safety system according to one of the preceding claims characterized in that the shut-off device (11) has an overpressure protection device.

9. Safety system according to one of the preceding claims characterized in that the refrigerant circuit (10) comprises a compressor (12), a refrigerant reservoir (13), a condenser (14) and an evaporator (15), wherein the shut-off device (11) is arranged directly before or directly after the compressor (12) in the refrigerant circuit (10).

10. Safety system according to claim 9 characterized in that several shut-off devices (11) are provided, wherein at least one first shut-off device (11a) is arranged between the condenser (14) and the compressor (12), at least one second shut-off device (11b) is arranged between the compressor (12) and the evaporator (15) and / or at least one third shut-off device (11c) is arranged between the evaporator (15) and the condenser (14).

11. Method for controlling a safety system of a refrigerant circuit (10) of a motor vehicle, in particular a safety system according to one of the preceding claims, wherein the method comprises the following steps: Detecting a vehicle impact using at least one impact sensor and / or detecting a refrigerant concentration in a passenger compartment exceeding a predetermined threshold using 102337-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH at least one refrigerant sensor and / or detection of a pressure drop in the refrigerant circuit (10) by means of a pressure sensor; Generation of a disconnect signal in a control unit connected to the at least one impact sensor and / or the at least one refrigerant sensor and / or the pressure sensor; Transmitting the disconnect signal to a shut-off device (11), in particular a drive or explosive device of a shut-off device (11), for actuating the shut-off device (11); and - Separation of the refrigerant circuit (10) by actuating the shut-off device (11) and - Switching off a compressor (12) of the refrigerant circuit (10). 102337-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

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