Vehicle cooling system comprising a variable displacement compressor

Abstract

Vehicle cooling system (100) comprising: a variable displacement compressor (104); and a controller (130) configured to generate a current signal in response to a determination that the compressor (104) is operating within a gurgling zone defined by a predefined range of compressor speeds and flows, which defines a displacement for the compressor (104) based on a speed of the compressor (104) and an ambient temperature in order to control the displacement to reduce coolant flow noise, wherein the controller (130) is further configured to generate the current signal based on the speed and the ambient temperature only if the ambient temperature is within a predefined temperature range.

Description

TECHNICAL FIELD

[0001] Disclosed herein is a vehicle cooling system comprising a variable displacement compressor. BACKGROUND

[0002] Vehicles often include air cooling systems to cool the ambient air within the vehicle's cabin. Such systems occasionally include variable-displacement compressors to meet varying cooling demands.

[0003] DE 10 2009 026 419 A1 discloses a method for controlling a compressor of an air conditioning device for a motor vehicle. SUMMARY

[0004] A vehicle cooling system may include a variable displacement compressor and a controller configured to, in response to a determination that the compressor is operating within a gurgling zone defined by a predefined range of compressor speeds and currents, generate a current signal defining a displacement for the compressor based on a speed of the compressor and an ambient temperature to control the displacement to reduce refrigerant flow noise.

[0005] A vehicle may include a variable displacement compressor associated with a climate control system; and a controller configured to receive vehicle data indicative of an ambient temperature and an engine speed, and, in response to a determination that the ambient temperature and engine speed fall within respective predefined ranges indicative of a gurgling zone of a compressor, generate a current signal for the compressor based on the ambient temperature and the engine speed to define a displacement for the compressor.

[0006] A method for a vehicle cooling system may include receiving vehicle data indicative of an ambient temperature and an engine speed; and in response to a determination that a compressor of the vehicle cooling system is operating within a gurgling zone based on the vehicle data, generating a current signal based on the vehicle data to control displacement of a compressor to reduce coolant flow noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The embodiments of the present disclosure are particularly pointed out in the appended claims. However, other features of the various embodiments will be more apparent and best understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 illustrates an exemplary vehicle cooling system; Fig. Figure 2 illustrates an example diagram for a gurgling zone based on compressor current and engine speed; Fig. 3 illustrates an exemplary block diagram for the cooling system; and Fig. 4 illustrates an example process for the cooling system. DETAILED DESCRIPTION

[0008] Detailed embodiments of the present invention are disclosed herein as appropriate; however, it should be understood that the disclosed embodiments are merely examples of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or reduced to show details of particular components. Accordingly, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0009] Vehicles often include air-cooling systems that utilize a variable-displacement compressor. At low compressor speeds and mild temperatures, vehicle cooling systems with variable-displacement compressors can generate refrigerant flow noise. This flow noise is associated with the thermodynamic condition where the refrigerant between the TXV and the condenser is a two-phase mixture of liquid and gas. This situation can occur when the variable displacement compressor is low to maintain the evaporator temperature, when the system heat load is low, and the compressor speed is low (e.g., when the vehicle is idling).

[0010] Disclosed herein is a controller configured to optimize compressor displacement to reduce refrigerant flow noise based on compressor speed and ambient temperatures. The controller can then "adjust" compressor displacement to eliminate refrigerant flow noise by generating a current signal that defines the compressor displacement and a relative setpoint for the suction pressure. The signal can "cap" the minimum control current that can be sent to the compressor.

[0011] Fig. 1 illustrates an example vehicle cooling system 100. The vehicle cooling system 100 may be configured to condition a vehicle cabin for passenger comfort by supplying air at a predetermined temperature. The vehicle cooling system 100 may be configured to process air according to an HVAC control strategy. The vehicle cooling system 100 may include an evaporator 102 and a compressor 104. The vehicle cooling system 100 may also include a condenser 108, an intake fan 110, and an ambient temperature sensor 114. The condenser 108 may expel heat to the ambient air via a fan.

[0012] Compressor 104 may be a variable displacement compressor configured to automatically adjust its refrigerant output based on a desired cabin temperature. Compressor 104 may include an intake passage 124 configured to receive refrigerant from evaporator 102. The speed of compressor 104 may be proportional to the degree of suction at intake passage 124. The speed of compressor 104 may be adjusted by adjusting the flow thereto.

[0013] The evaporator 102 may pass refrigerant to the compressor 104. The compressor 104 may then compress the refrigerant into high-pressure, high-temperature superheated vapor. The superheated refrigerant condenses into a liquid in the condenser 108. The refrigerant flows to a dryer 118, which then passes to a thermal expansion valve (TXV) 120. The TXV 120 is configured to control the amount of refrigerant entering the evaporator 102. When the temperature of the refrigerant leaving the evaporator 102 is above a threshold, the TXV 120 allows more refrigerant to flow into the evaporator 102. When the temperature of the refrigerant leaving the evaporator 102 is below a threshold, the TXV 120 decreases the amount of refrigerant flowing into the evaporator 102. The TXV 120 limits the flow of coolant, resulting in a pressure drop in the coolant.

[0014] A fan (not shown) may blow air through the evaporator 102, transferring heat from the air to the refrigerant. The cooled air is blown into the vehicle cabin 116. The refrigerant leaving the evaporator 102 is superheated vapor at low pressure and low temperature, which then flows to the compressor 104, and the cycle continues. A cabin temperature sensor 122 may be located in or near the vehicle cabin 116 to detect the vehicle cabin temperature.

[0015] The vehicle cooling system 100 may include a controller 130 configured to receive data from the components of the vehicle cooling system 100. The controller 130 may also be configured to control the operation of the vehicle cooling system 100 based on the received data, among other data, preferences, profiles, etc. The controller 130 may be configured to receive inputs from a vehicle occupant via a user interface (not shown) in the vehicle cabin 116, such as a graphical user interface, a head-up display, a mobile device, etc. The inputs may reflect a desired cabin temperature. The user interface may also include a vehicle instrument panel configured to allow a vehicle occupant to manually control the conditions within the vehicle cabin.

[0016] The controller 130 may communicate with other vehicle components and systems. In one example, and as shown in Fig. As shown in Figure 1, the controller 130 may communicate with an engine control unit (ECU) 132. The engine control unit 132 may be configured to control various vehicle components, including the engine. The ECU 132 may also be configured to receive engine data, among other vehicle data. The engine data may include a current engine speed (i.e., engine RPM) and an engine state, such as idle, park, drive, etc. In some examples, the engine state or the vehicle state may be determined by the engine speed.

[0017] The vehicle state may include one of a variety of predetermined vehicle states. These predetermined vehicle states may correspond to a vehicle state in which the vehicle is not moving but is still conditioning the vehicle cabin via the vehicle cooling system 100. In one example, the predetermined vehicle state may be an idle state, a park state, a recirculation state, a fresh state, a low fan state, etc. The idle state and the park state may be based on the current drive gear of the vehicle. The recirculation state may occur when air is being conditioned and is not flowing into or out of the cabin interior. The fresh state may occur when outside air is being conditioned, flowing into the cabin interior, and continuing to flow out to the outside air.The low fan condition may occur when the fan is not blowing or is blowing at a reduced speed. Controller 130 may then use this information to control vehicle cooling system 100.

[0018] Controller 130 may also receive inputs from the various sensors in the vehicle and vehicle cooling system 100. For example, controller 130 may receive an ambient temperature from ambient temperature sensor 114. Controller 130 may receive a cabin temperature from cabin temperature sensor 122.

[0019] Controller 130 may control compressor current based on various received user and sensor inputs. Various heuristics may be executed by controller 130 to provide optimal passenger comfort. Controller 130 may also consider vehicle condition and other vehicle systems and components when determining compressor current. For example, controller 130 may adjust compressor current based on ambient temperature, vehicle condition, and engine speed. This is described in more detail below.

[0020] Fig. 2 illustrates an example gurgling zone diagram 200 based on compressor current and engine speed. In driving situations where the ambient temperature is within a predefined temperature range (e.g., approximately 45 degrees to 85 degrees Fahrenheit (approximately 7.2°C to 29.4°C)) and the compressor speed is low (e.g., 1000-1100 rpm), the compressor may generate coolant flow noise that passengers in the vehicle cabin may hear. This often occurs in response to the coolant between the TXV 120 and the condenser being a mixture of liquid and gas. In this thermodynamic state, the flow noise is audible, especially when the vehicle is idling. In other words, when the heat load in the vehicle cooling system 100 is low and the compressor speed is low, the vehicle cooling system 100 may generate a "gurgling" noise.Such noise, vibration, and harshness (NVH) can reduce driver satisfaction.

[0021] For example, at an ambient temperature of 72 degrees Fahrenheit (approximately 22.2°C), coolant flow noise may be more noticeable in four-cylinder engines at idle, where the compressor idle rpm is approximately 1000-1100 rpm. In another example, coolant flow noise may be much worse in six-cylinder engines, where the compressor idle rpm is approximately 850-950 rpm.

[0022] A low heat load can occur when the ambient temperature is relatively mild (e.g., approximately 72 degrees Fahrenheit (approximately 22.2 °C)) and the cabin temperature is also approximately the same. In this situation, the compressor speed may be low and the evaporator temperature may be low.

[0023] In relation to Fig. 2, a gurgling zone can be introduced based on specific engine speeds and compressor currents. In the example shown in Fig. 2, the gurgling zone may be implemented when the engine speed is within a predefined speed range (e.g., between 600 and 900 rpm) and when the compressor current is within a predefined current range (between 350 and 500 mA). In the gurgling zone, the controller 130 may be configured to adjust the compressor current in an effort to eliminate or reduce the NVH generated by the vehicle cooling system 100. That is, the controller 130 may determine a minimum amount of compressor current required to meet the demands of the vehicle cooling system 100. By reducing the current, the mass flow of coolant may be reduced, thereby preventing gurgling and reducing the NVH.

[0024] Fig. 3 illustrates an example block diagram for the vehicle cooling system 100. The controller 130 may include or communicate with a database 140. The database 140 may include various lookup tables for the vehicle cooling system 100 so that the vehicle cooling system 100 can "tune" or adjust the compressor current to mitigate or reduce the NVH generated by the coolant flow. The lookup tables may include vehicle-specific minimum currents at which the compressor 104 may operate based on a specific set of circumstances. For example, the compressor current may be capped at a certain value within a certain ambient temperature range and at a certain compressor speed. Once the controller 130 determines the updated current, the updated current may be communicated to the compressor 104 via a current signal.By adjusting the compressor current, the displacement of the compressor 104 can be optimized by “capping” the minimum control current that can be sent to the compressor 104 (e.g., 0.6 mA-0.8 mA).

[0025] Fig. 4 illustrates an example process 400 for the vehicle cooling system 100. The process 400 may begin at block 405. At block 405, the controller 130 may receive vehicle data indicative of various vehicle conditions, states, etc. The vehicle data may also include air cooling data indicative of sensor data from the vehicle cooling system 100, as well as other parameters such as compressor speed and compressor current, etc.

[0026] At block 410, the controller 130 may determine whether the ambient temperature is within a predefined temperature range. For example, the predefined temperature range may be between 70 and 80 degrees Fahrenheit (approximately 21.1°C and 26.6°C), although the ranges may vary. In one example, an ambient temperature of 72 degrees Fahrenheit (approximately 22.2°C) may be considered to be within the predefined temperature range. If the ambient temperature is within the predefined temperature range, the process 400 continues to block 415. If not, the process 400 ends.

[0027] At block 415, the controller 130 may determine whether the vehicle is in a predetermined stationary state. As previously discussed, the predetermined vehicle state may correspond to a state where the vehicle is not moving but is still conditioning the vehicle cabin via the vehicle cooling system 100. In these states, other vehicle NVH may be minimal, making condenser gurgling more noticeable. In one example, the predetermined vehicle state may be an idle state, a park state, a recirculation state, a cool state, a low blower state, etc. If the vehicle is in a stationary state, the process 400 proceeds to block 420.

[0028] At block 420, controller 130 may determine whether the compressor current is within a predefined current range. As previously explained, the predefined current range may be between 350 and 500 mA. If the compressor current is within the current range, process 400 proceeds to block 425. If not, process 400 ends.

[0029] At block 425, the controller 130 may determine whether the engine speed is within a predefined speed range. The predefined speed range may correspond to the engine speed at which gurgling is most likely to occur. For example, the range may be between 600 and 900 rpm. If the engine speed is within the speed range, the process 400 continues to block 430. If not, the process 400 ends.

[0030] At block 430, controller 130 may determine the ideal compressor displacement and associated compressor current based on the vehicle data. As previously explained, the set compressor current may be determined using a vehicle-specific lookup table in database 140. The compressor speed and ambient temperature may be used to determine the set compressor current.

[0031] The controller 130 may transmit a current signal including the set compressor current to the compressor 104. The process 400 may then end.

[0032] Accordingly, a variable-displacement compressor flow can be adjusted based on the compressor speed and ambient temperature. By adjusting the compressor flow, the suction at the compressor intake port can be adjusted to reduce the gurgling noise generated in light-load situations. By managing the compressor flow, the need for isolators to prevent undesirable NVH and other noise can be eliminated. An overall better user experience can be achieved while maintaining the efficiency of the vehicle's cooling system.

[0033] Computing devices, such as the controllers, etc., generally include computer-executable instructions, where the instructions may be executed by one or more computing devices, such as those listed above. Computer-executable instructions may be compiled or interpreted by computer programs created using a variety of programming languages ​​and / or technologies, including, but not limited to, either alone or in combination, Java™, C, C++, Visual Basic, Java Script, Perl, etc. In general, a processor (e.g., a microprocessor) receives instructions, e.g., from memory, a computer-readable medium, etc., and executes those instructions, thereby performing one or more processes, including one or more of the processes described herein.Such instructions and other data may be stored and transmitted using a variety of computer-readable media.

[0034] Databases, data repositories, or other data stores described herein may include various types of mechanisms for storing, accessing, and retrieving various types of data, including a hierarchical database, a series of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store is generally encapsulated in a computing device employing a computer operating system, such as one of those listed above, and is accessed in one or more possible ways over a network. A file system may be accessed by a computer operating system, and the files may be stored in various formats.An RDBMS generally uses the Structured Query Language (SQL) in addition to a language for creating, storing, manipulating, and executing stored procedures, such as the PL / SQL language listed above.

[0035] In some examples, system elements may be implemented as computer-readable instructions (e.g., software) on one or more computing devices (e.g., servers, personal computers, etc.) stored on computer-readable media (e.g., disks, memory, etc.) associated therewith. A computer program product may include such instructions stored on computer-readable media for performing the functions described herein.

[0036] While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the invention. The terms used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. In addition, the features of various implementing embodiments may be combined to form further embodiments of the invention.

Claims

[1] Vehicle cooling system (100) comprising: a variable displacement compressor (104); and a controller (130) configured, in response to a determination that the compressor (104) is operating within a gurgling zone defined by a predefined range of compressor speeds and currents, to generate a current signal defining a displacement for the compressor (104) based on a speed of the compressor (104) and an ambient temperature to control the displacement to reduce refrigerant flow noise, wherein the controller (130) is further configured to generate the current signal based on the speed and the ambient temperature only when the ambient temperature is within a predefined temperature range. [2] The vehicle cooling system (100) of claim 1, wherein generating the current signal based on the speed and the ambient temperature includes checking a vehicle-specific lookup table. [3] The vehicle cooling system (100) of claim 1, wherein the gurgling zone is further defined by a vehicle condition that is an idle condition, a park condition, a recirculation condition, a fresh condition, or a low fan condition. [4] Vehicle comprising: a variable displacement compressor (104) linked to an air conditioning system; and a controller (130) configured to: to receive vehicle data indicating ambient temperature and engine speed, and in response to a determination that the ambient temperature and engine speed fall within respective predefined ranges indicative of a gurgling zone of the compressor (104), generate a current signal for the compressor (104) based on the ambient temperature and the engine speed to define a displacement for the compressor (104). [5] The vehicle of claim 4, wherein generating the current signal based on the ambient temperature and the engine speed includes checking a vehicle-specific lookup table. [6] The vehicle of claim 4, wherein the controller (130) is further configured to generate the current signal based on the ambient temperature and the engine speed only when the compressor current is within a predefined current range. [7] The vehicle of claim 4, wherein the controller (130) is further configured to generate the current signal based on the ambient temperature and the engine speed only when the vehicle is in an idle state, a park state, a return state, a fresh state, or a low fan state. [8] A method for a vehicle cooling system (100), comprising: Receiving vehicle data indicating an ambient temperature and an engine speed; and in response to a determination that the ambient temperature and engine speed fall within respective predefined ranges indicative of a gurgling zone of a compressor (104), generating a current signal based on the vehicle data to control the displacement of the compressor (104) to reduce coolant flow noise, wherein the generation is performed only when a compressor current is within a predefined current range. [9] The method of claim 8, wherein generating includes checking a vehicle-specific lookup table.

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