US20080110185A1

US20080110185A1 - Vehicle HVAC system

Info

Publication number: US20080110185A1
Application number: US11/905,498
Authority: US
Inventors: Rajesh Veettil; Robert Banules; Terry Borths; Carl Dalkert; Fernando deCampos; Derek F. Klima
Original assignee: Behr America Inc
Current assignee: Mahle Behr USA Inc
Priority date: 2006-09-29
Filing date: 2007-10-01
Publication date: 2008-05-15

Abstract

An auxiliary climate control system may include a plurality of evaporators arranged in series. The auxiliary climate control system may comprise a first evaporator coupled to a first compressor and a first condenser, a second evaporator coupled to a second compressor and a second condenser, and a blower configured to move air past the first evaporator and the second evaporator. The first compressor may be configured to operate when a vehicle engine is running and the second compressor is configured to operate on power from a source independent of the running engine such that the second compressor may operate when the engine is not running.

Description

The present application claims benefit of priority to U.S. Provisional Application Ser. No. 60/827,620, filed Sep. 29, 2006, the entire contents of which is incorporated herein by reference.
This application relates generally to climate control (heating, ventilating and air-conditioning, or HVAC) systems. More particularly, this application relates to HVAC systems used for motor vehicles.

BACKGROUND

Primary HVAC systems are often included for climate control of motor vehicles. These systems heat and/or cool air circulated in the occupant cabin of the vehicle. Some of these systems require energy from the vehicle engine such that the vehicle engine must be running (i.e. idling) for the HVAC system to be fully functional when the vehicle is parked. This is particularly an issue with vehicles that are commonly occupied while parked, such as recreational vehicles (RVs), busses, commercial trucks with sleeper cabs, and other such vehicles. However, idling a vehicle engine for a period of time to operate the HVAC system consumes relatively large quantities of fuel and generates exhaust.
To avoid unnecessary fuel consumption and limit the generation of exhaust while still providing a comfortable cabin temperature, auxiliary HVAC units that are independent of the vehicle engine have been used. These systems are generally free standing from the primary HVAC system of the vehicle. Such systems may require distribution ducting that is independent of the primary HVAC system. These systems may also require separate control interfaces from those for the primary HVAC system. These systems may also require multiple blower motors for use with the primary and auxiliary HVAC systems.
Accordingly, there is a need for an integrated auxiliary HVAC system that incorporates the primary and auxiliary HVAC systems. There is also a need for an integrated HVAC system that may be controlled by a single user interface.

SUMMARY

One embodiment relates to an auxiliary climate control system including a plurality of evaporators arranged in series. In some of these embodiments, an auxiliary climate control system for a vehicle comprises a first evaporator coupled to a first compressor and a first condenser, a second evaporator coupled to a second compressor and a second condenser, and a blower configured to move air past the first evaporator and the second evaporator. The first compressor may be configured to operate when a vehicle engine is running and the second compressor is configured to operate on power from a source independent of the running engine such that the second compressor may operate when the engine is not running.
Other embodiments relate to an auxiliary climate control system for a vehicle comprising a first evaporator in fluid communication with a first compressor and a first condenser; a second evaporator in fluid communication with a second compressor and a second condenser; and a blower configured to move air past both the first evaporator and the second evaporator. In these embodiments, the first evaporator is not in fluid communication with the second evaporator.
In yet other embodiments, an auxiliary climate control system for a vehicle may comprise a first evaporator in fluid communication with a first compressor and a first condenser; a second evaporator in fluid communication with a second compressor and a second condenser; a blower configured to move air past both the first evaporator and the second evaporator; and a heater core in fluid communication with a coolant heater. In these embodiments, an actuator may be configured to direct some portion or all of the air flow past the heater core.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an integrated HVAC system.

FIG. 2 is a fragmentary cross-sectional view of a portion the HVAC system of FIG. 1.

FIG. 3 is a fragmentary cross-sectional view of a portion the HVAC system of FIG. 1.

FIG. 4, is a side elevation view of a portion of the HVAC system of FIG. 1.

FIG. 5 is a front elevation view of a portion of the HVAC system of FIG. 1.

FIG. 6 is a schematic view of a coolant loop.

FIG. 7 is a schematic view of a vehicle HVAC system.

DETAILED DESCRIPTION

FIG. 1 illustrates an integrated HVAC system for use in a vehicle. The integrated HVAC unit includes an auxiliary HVAC unit and a compressor/condenser unit. The auxiliary HVAC unit may be contained within the cab and generally includes an air inlet, a blower with a linear power module, such as, for example, a brushless direct current (BLDC) blower motor, a starter module 5 a and air outlets 9.
In the preferred embodiment of FIG. 1, the compressor/condenser unit 1 is configured to be mounted on the exterior of the vehicle. Condensed refrigerant is circulated from the condenser to the 2^nd evaporator 2 of the auxiliary HVAC unit (shown in FIG. 2). Condensed refrigerant is evaporated to cool air entering the air inlet 3 of the auxiliary HVAC unit. The evaporated refrigerant is then recirculated to the compressor/condenser unit 1 as in a conventional refrigeration cycle.
In this preferred embodiment, a coolant heater 4 is coupled to the compressor/condenser unit 1. In a preferred exemplary embodiment, the coolant heater 4 may be a fuel fired heater (FFH) that bums fuel from the vehicle fuel supply to heat the cabin. One suitable FFH is a diesel fueled heater commercially available from ESPAR of Mississauga, Ontario. In the case of a FFH, the coolant heater may be coupled to the compressor/condenser unit 1 on the exterior of the vehicle to allow for safe venting of exhaust gasses. Alternatively, the coolant heater 4 may be mounted closer to or on the auxiliary HVAC unit if, for example, the coolant heater 4 is an electric heater or other device that does not require venting of exhaust gasses.
In some embodiments, the coolant heater 4 may be coupled to the engine cooling system such that engine coolant may be circulated through the coolant heater and the heater core in the auxiliary HVAC unit. Alternatively, the coolant heater 4 and heater core may be isolated from the engine cooling system (i.e. on a separate closed coolant loop).
The integrated HVAC systems may be powered by a variety of power sources that are independent of the engine. For example, the auxiliary HVAC system may be powered by an auxiliary power unit (APU), vehicle batteries, batteries dedicated to the auxiliary HVAC system, or shore power (i.e. AC power). In one preferred embodiment, the compressor motor is designed as a 110 volt AC motor.
FIGS. 2 and 3 illustrate the auxiliary HVAC unit of FIG. 1 and the general flow of air therethrough. The auxiliary HVAC unit generally includes an air inlet 3, a 2^nd evaporator 2, a blower motor 5 such as, for example, a BLDC blower motor, a main evaporator 6, an actuator (shown as a temperature door (temp. door)) 7, a heater core 8, and an air outlet 9. An air inlet filter 10 may be positioned in the air inlet 3 to remove particulates that may damage the auxiliary HVAC unit or that are not desired in the outlet air stream. An air inlet sensor 11 may also be used to monitor the temperature of the air entering the unit and a freeze protection sensor 12 may be used to detect ice forming on or near the 2^nd evaporator 2.
As illustrated in FIG. 3, in some embodiments, air may be drawn into the air inlet by the blower motor. The inlet air may be recirculated from the cabin, or the air may be fresh air drawn from outside the vehicle. The temperature of the inlet air is measured by the air inlet sensor. This temperature measurement may be used by a controller logic that controls the coolant heater, refrigerant system, temperature door, and/or blower motor. The air passes through the 2^ndevaporator where the air may be cooled. The 2^ndevaporator is coupled to the compressor/condenser unit (shown in FIG. 1) which is operated when the vehicle is parked and not idling.
The air is then drawn into the blower motor where it is accelerated. Upon exiting the blower motor, the air stream passes through the main evaporator where it may be cooled. The main evaporator may be coupled to the vehicles primary air cooling system (i.e. the primary compressor and condenser). The air then passes the temperature door.
The temperature door may be controlled to regulate the flow of air through the heating core. When the temperature door is moved to a position for maximum cooling, the temperature door blocks airflow to the heating core such that the cool air that has been cooled at one or more of the evaporators bypasses the heating core. When the system is used for maximum heating, the temperature door directs substantially all of the air flow through the passage where the heating core is located. Heat is supplied to the heater core by hot circulated coolant (e.g., an ethylene glycol and water mixture) that has been heated in the coolant heater (e.g. the FFH coupled to the compressor/condenser unit).
The heated or cooled air then passes a discharge sensor 13 that measures the temperature of the air exiting the auxiliary HVAC unit. The temperature measurement may be used by a controller logic that controls the coolant heater, refrigerant system, temperature door, and/or blower motor.
The air then exits the auxiliary HVAC unit at the air outlet. The air outlet may be coupled to an auxiliary duct system, or the vehicles primary air distribution system.
When the vehicle engine is running, the 2^ndevaporator may be used in conjunction with the main evaporator to cool the cabin air (i.e. to provide additional cooling capacity when required). In alternative embodiments, the 2^ndevaporator and the main evaporator may both be upstream of the blower motor (i.e. between the inlet and the blower motor). In yet other embodiments, both the 2^ndevaporator and the main evaporator may both be down steam of the blower motor. In even yet other embodiments, the 2^ndevaporator may be downstream of the blower motor while the main evaporator is upstream of the evaporator.
The auxiliary HVAC unit may be positioned in a cabin zone. For example, in a commercial truck, the auxiliary unit may be placed in a sleeper cab. In such embodiments, the main evaporator may be coupled to the vehicle's primary HVAC system to cool the sleeper cab while the vehicle is operating. If needed, the auxiliary HVAC unit may be used to provide additional cooling capacity. When the vehicle is parked and not idling (i.e. for a driver break) the main evaporator is not used but the 2^ndevaporator is used to cool the sleeper cab. The external compressor/condenser unit is used to supply condensed refrigerant to the condenser and may be powered by an APU, vehicle batteries, batteries dedicated to the auxiliary HVAC system, and/or shore power such as a 110 volt AC power supply.
FIGS. 4 and 5 illustrate the compressor/condenser unit shown in FIG. 1. Expanded refrigerant is circulated to the compressor where the refrigerant is pressurized. The compressed refrigerant is liquefied in the condenser. The pressurized liquid refrigerant passes through coolant lines 14 and is then evaporated in the 2^ndevaporator to absorb heat from the inlet air. Because the compressor, condenser, and evaporator comprise a closed loop, these components may be pre-charged with refrigerant prior to installation in a vehicle.
The auxiliary HVAC unit may include a control interface for a user to select the temperature and/or blower speed. In some embodiments, the same controller interface may be used to regulate both the main evaporator when the vehicle is operating and the 2^ndevaporator when the vehicle is parked and not idling. In a preferred embodiment, the vehicle operator is provide with a single control panel to control the cabin comfort irrespective of whether either or both of the first and second refrigeration systems (i.e., main and 2^ndevaporators) is/are operating. For example, the single control panel may have only two control settings, one for temperature and another for fan speed.
The heater core of the auxiliary HVAC unit receives circulated, heated coolant from the coolant heater via a coolant line 15. In some embodiments the coolant heater is a FFH. The FFH may be operated using the vehicles fuel (i.e. gasoline or diesel). An exhaust port 16 vents the FFH exhaust to the exterior of the cabin.
FIG. 6 illustrates a coolant loop layout that may be employed with the auxiliary HVAC system. In some embodiments, a main HVAC heater core receives hot coolant from the vehicle engine when the vehicle is running. The engine coolant is also circulated to the coolant heater (shown as a fuel fired heater) which is in series with the heater core of the auxiliary HVAC unit. The heater core and coolant heater are in parallel with the main HVAC heater core. When the vehicle is parked and not idling, coolant may be heated in the coolant heater and circulated to the heater core to warm the air in a cabin zone (e.g. the sleeper cab). The coolant is also circulated to the main HVAC heater core such that other areas of the cabin may be heated. Valve B is closed to prevent circulation of the coolant to the engine where heat would be lost.
When the engine is running, valve B and valve A may be opened to utilize heat generated by the engine for heating the cabin. Valve A may also be closed such that hot coolant is circulated to the engine to warm the engine up prior to or just after starting.
FIG. 7 illustrates a schematic view of a vehicle HVAC system. The HVAC system includes three separate loops: cooling loop A, cooling loop B, and heating loop C. Cooling loop A comprises an auxiliary compressor 20, an auxiliary condenser 21 and a 2^nd evaporator 22. In some embodiments, the auxiliary compressor 20 is powered by a power source independent of the running vehicle engine. Included in such power sources are the vehicle batteries or other batteries that may be recharged when the engine is running. Alternatively, the auxiliary compressor may run on shore power.
Cooling loop B comprises a main compressor 23, a main condenser 24, a main evaporator 25 and a 2^nd main evaporator 26. The main evaporator 25 and 2^nd main evaporator 26 are shown in parallel, however, the main evaporator 25 and second main evaporator 26 could be arranged in series. Alternatively, the main evaporator 25 and 2^nd main evaporator 26 could be on separate cooling loops. The main evaporator 25 and second main evaporator 26 may be used to cool zones of a vehicle cabin. For example, the main evaporator 25 may be located in the sleeper cab of a commercial truck, while the 2^nd main evaporator 26 may be located near the driver's area of the cab to allow cooling of multiple zones from cooling loop B. The main compressor may, in some embodiments, be powered by mechanical energy generated by the vehicles engine.
Heating loop C is configured as the loop shown in FIG. 6. Heating loop C comprises a coolant heater (shown as a fuel fired heater) 27, a heater core 28, a main heater core 29, and the vehicle engine 30. Valves A31 and B32 regulate the flow of coolant as described above.
The auxiliary condenser 21, auxiliary compressor 20, and coolant heater 27 may be located in the compressor/condenser unit 32 mounted on the exterior of the vehicle (see FIG. 1). The main evaporator 25, 2^nd evaporator 26, and the heater core may be located in the auxiliary HVAC unit, as shown in FIG. 2. Alternatively, the auxiliary condenser 21, auxiliary compressor 20, and coolant heater 27 may be integrated into the auxiliary HVAC unit 33, to produce a single compact unit that is designed to be mounted inside of the vehicle cab, preferably adjacent an outside wall. In such an embodiment, a single casing would encompass both of the portions that are shown in FIG. 7 as being encompassed by separate casings.
Placing the 2^nd evaporator 22 and the main evaporator 25 in the auxiliary HVAC unit 33, preferably in the same air flow pathway, facilitates the use of a single control interface for operation of the auxiliary HVAC unit 33 to both cool a cabin zone when the vehicle is running and when the vehicle is parked and not idling. The control interface may be mounted to the auxiliary HVAC unit 33 and may comprise two controls such as dials or switches. The two controls may be used to regulate temperature and fan speed. This single control interface therefore operates both the main HVAC system and the auxiliary HVAC system 33, improving both the convenience and the compactness/cost effectiveness of the system according to the invention. The latter advantages are further enhanced due to the fact that the main HVAC and auxiliary HVAC systems also share a single fan and ducting structure in the auxiliary unit.
Although the foregoing has been described with reference to examplary embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope thereof. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. The present subject matter described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.

Claims

1. An auxiliary climate control system for a vehicle comprising:

a first evaporator coupled to a first compressor and a first condenser;

a second evaporator coupled to a second compressor and a second condenser;

a blower configured to move air past the first evaporator and the second evaporator;

wherein the first compressor is configured to operate when a vehicle engine is running; and

the second compressor is configured to operate on power from a source such that the second compressor may operate when the engine is not running.

2. The auxiliary climate control system of claim 1, wherein the second compressor is configured to operate on power supplied by shore power.

3. The auxiliary climate control system of claim 1, wherein the one of the first evaporator and the second evaporator is upstream of the blower and the other of the first evaporator and the second evaporator is downstream of the blower.

4. The auxiliary climate control system of claim 1, further comprising a heater core coupled to a coolant heater.

5. The auxiliary climate control system of claim 4, wherein the coolant heater is coupled to the engine coolant system.

6. An auxiliary climate control system for a vehicle comprising:

a first evaporator in fluid communication with a first compressor and a first condenser;

a second evaporator in fluid communication with a second compressor and a second condenser;

a blower configured to move air past both the first evaporator and the second evaporator; and

wherein the first evaporator is not in fluid communication with the second evaporator.

7. An auxiliary climate control system for a vehicle comprising:

a blower configured to move air past both the first evaporator and the second evaporator;

a heater core in fluid communication with a coolant heater;

an actuator configured to direct air flow past one or more of the first evaporator, the second evaporator, and the heater core.

8. A method for controlling the temperature of a vehicle cabin comprising:

passing inlet air past a first evaporator, the first evaporator coupled to a first compressor;

passing the inlet air past a second evaporator, the second evaporator coupled to a second compressor;

the second compressor is configured to operate on power from a source independent such that the second compressor may operate when the engine is not running.

9. A method for controlling the temperature of a vehicle cabin comprising:

passing air through an HVAC unit comprising a first evaporator and a second evaporator;

controlling the temperature of the air exiting the HVAC unit both when the vehicle engine is running and when the engine is off using a single controller interface;

wherein the first evaporator is coupled to a first compressor configured to operate when a vehicle engine is running; and

the second evaporator is coupled to a second compressor configured to operate on power from a source such that the second compressor may operate when the engine is not running.