Patent Application
20050257545
The present invention relates generally to automotive heating, ventilation, and air conditioning (HVAC) systems and methods of operating such HVAC systems.
Hybrid vehicles, which utilize an internal combustion engine and a battery-powered electric motor for vehicle movement, are becoming more and more popular because of their increased fuel efficiency as compared to those vehicles having only an internal combustion engine. In a typical hybrid vehicle control, the engine is utilized in higher power requirement situations and the motor is utilized during starting, braking, and in lower power requirement situations.
Hybrid vehicles, in particular, have had concerns because of the need to provide cooling when the engine is not running in warmer ambient conditions. HVAC compressors are typically driven by the engine through a clutch or the like and, therefore, do not function when the vehicle engine is not running. With the engine and compressor off, the interior of the vehicle may heat up quickly, disadvantageously requiring the engine to be operated solely for the purpose of providing cooling to the occupants of the vehicle.
It is desirable, therefore, to provide a HVAC system that allows the engine in a hybrid vehicle to remain off while still keeping the occupants of the vehicle cool and comfortable. It is also desirable to provide a HVAC system that allows for greater flexibility and efficiency of operation, regardless of the type of vehicle.
The present invention concerns an automotive HVAC system for use in a vehicle having a vehicle body that includes an engine and a battery. The HVAC system has a predetermined design cooling capacity and includes a condenser and one of an orifice tube and an expansion valve in fluid communication with the condenser. A first compressor is adapted to be mechanically driven by the engine and is in fluid communication from the evaporator and in fluid communication to the condenser. A second compressor is electrically connected to and driven by the battery bank and is in fluid communication from the evaporator and in fluid communication to the condenser. Each of the compressors is selectively operable to compress refrigerant in the HVAC system during operation of the HVAC system.
The first and second compressors may be in fluid communication with the condenser in a parallel configuration wherein the first compressor and the second compressor each have a distinct suction line in fluid communication with the evaporator. In the parallel configuration, the first and second compressors discharge into a common discharge line that is in fluid communication with the condenser. Alternatively, the first and second compressors may be in fluid communication with the condenser in a series configuration wherein the first compressor discharges into the suction of the second compressor and the second compressor discharges to the condenser. Regardless of the series or parallel configuration, each of the compressors may be operated individually.
Each of the compressors has a pumping or cooling capacity equal to a predetermined value and the HVAC system has a design cooling capacity equal to a predetermined value. The respective values of the pumping or cooling capacity of the compressors may vary depending on the cooling capacity requirements of the HVAC system and the packaging requirements of the vehicle body.
The electric-drive compressor allows for extended hybrid engine off operation of the vehicle while maintaining A/C comfort and enables vehicle preconditioning, wherein the electric-drive compressor runs to cool the passenger compartment prior to occupant entry. The cooling capacities of the compressors may be advantageously sized so that the operation of the HVAC system is more efficient than using a single large electric-drive or mechanical-drive compressor because each of the compressors of the present invention may be sized smaller to operate during less demand and thus consume less energy.
The HVAC system in accordance with the present invention provides greater vehicle packaging flexibility because a smaller electric-drive compressor can be located on or off the vehicle engine. In contrast, a dual-drive compressor is a larger package that must be on the engine and a single larger electric-drive compressor is more difficult to locate in the vehicle engine compartment.
The HVAC system in accordance with the present invention is well suited for use in hybrid vehicles. The HVAC system, however, may also be advantageously utilized in standard or conventional vehicles having only internal combustion engines wherein the second electric compressor runs when the cooling demand is reduced or lowered, which eliminates the parasitic load of the engine-driven compressor and increases the overall fuel efficiency of the vehicle.
The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which:
Referring now to
A first compressor 36 has an inlet 38 in fluid communication with the compressor suction conduit 34 and an outlet 40 in fluid communication with a compressor discharge conduit 42. The compressor discharge conduit 42 is in fluid communication with the inlet 16 of the condenser 14. The first compressor 36 is adapted to be driven by an engine (not shown) of the vehicle, such as by a belt and pulley assembly driven by a crankshaft (not shown) or the like. The first compressor 36 may be a fixed or variable displacement compressor, as will be appreciated by those skilled in the art and may also be engaged and disengaged from the engine by a clutch 54, if desired. A second compressor 44 has an inlet 46 in fluid communication with the compressor suction conduit 34 and an outlet 48 in fluid communication with the compressor discharge conduit 42. The second compressor 44 includes a motor that is electrically connected to and driven by a battery bank (not shown) disposed in the vehicle. The second compressor 44 may be a fixed or variable displacement compressor, as will be appreciated by those skilled in the art.
Each of the compressors 36 and 44 has a pumping or cooling capacity equal to a predetermined value and the HVAC system 10 has a design cooling capacity equal to a predetermined value. The respective values of the pumping or cooling capacity of the compressors 36 and 44 may vary depending on the cooling capacity requirements of the HVAC system 10. For example, the first compressor 36 may have a maximum capacity equal to the design cooling capacity of the HVAC system 10 and the second compressor 44 may have a maximum capacity less than the design cooling capacity of the HVAC system 10. Similarly, the maximum capacity of the first compressor 36 and the maximum capacity of the second compressor 44 may each be a predetermined percentage of the design cooling capacity of the HVAC system 10 wherein, for example, the maximum capacity of the first compressor 36 and the maximum capacity of the second compressor 44 equal, in sum, the design cooling capacity of the HVAC system 10. Those skilled in the art will appreciate that the respective capacities of the first compressor 36 and the second compressor 44 may vary, depending on the specific design requirements and/or packaging restrictions of the vehicle body 12 and the HVAC system 10, while remaining within the scope of the present invention.
In
Referring now to
At least a first valve 66 is disposed adjacent the outlet 40 of the first compressor 36, and at least a second valve 68 is disposed adjacent the inlet 46 of the second compressor 44. The first valve 66 is preferably a three-way valve that selectively allows flow from the outlet 40 of the first compressor 36 to either the series conduit 50 or the compressor discharge conduit 42. The second valve 68 allows flow to the inlet 46 of the second compressor 44 from the compressor suction conduit 34 when open and from the series conduit 50 when closed. Other valves (not shown) such as stop valves, check valves, and the like may be disposed in appropriate locations such as adjacent the respective inlets 38 and 46 and outlets 40 and 48 of the compressors 36 and 44 as well as in the series conduit 50, the compressor suction conduit 34, and the compressor discharge conduit 42. These valves and the valves 66 and 68 allow the compressors 36 and 44 to be isolated from one another and from the other components of the HVAC system 10′ during dual or single compressor operation.
Referring now to
In operation, the HVAC system 10 or 10′ is engaged and compressors 36 or 44 are operated to compress refrigerant contained in the piping of the HVAC system 10 or 10′ to provide cooled air to the interior of the vehicle body 12. During operation of the HVAC system 10 or 10′, the controller 52 monitors the temperature in the interior of the vehicle body 12, and the output and condition of the compressors 36 or 44. Typically, the controller 52 will include stored values corresponding to the design cooling capacity of the HVAC system 10 or 10′, and the respective cooling capacities of the compressors 36 and 44. The controller 52 will also calculate the current cooling demand requirements of the HVAC system 10 or 10′ based on, for example, temperatures measured by the temperature measurement devices 60 and 62 or the like and the settings of the HVAC system 10 or 10′ by the vehicle occupants. Depending on the calculated cooling demand, and the respective cooling capacities of the compressors 36 and 44, the controller 52 engages the first compressor 36, the second compressor 44, or both the first compressor 36 and the second compressor 44 to provide cooled air to the interior of the vehicle body 12. In addition, if the compressors 36 or 44 are variable displacement compressors, the controller 52 may vary the displacement of the compressors 36 or 44, depending on the calculated cooling demand. Moreover, depending on the configuration of the HVAC system 10 or 10′, the controller 52 will also open or close the necessary valves 66 and/or 68 when engaging the compressors 36 and/or 44.
For example, the vehicle may be a hybrid vehicle that utilizes an internal combustion engine, such as the engine 56 of
The vehicle may also be a standard vehicle that utilizes an internal combustion engine, such as the engine 56 of
Depending on the type of vehicle and the current operating conditions, the controller 52 monitors temperatures, calculates cooling demand, and operates the compressors 36 and 44 in a manner that will meet the cooling demand calculated by the controller 52 in the most efficient manner.
In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.
