Patent Application
20070259614
The present invention relates to the field of air handling systems. More specifically, the present invention relates to an actuation system for controlling movement of doors in an air handling system for a vehicle.
Vehicles, such as automobiles, vans, trucks, and the like, are typically provided with an air handling system, commonly referred to as a heating, ventilation, and air conditioning (HVAC) system. HVAC systems provide temperature control via selection between heating, ventilation, and cooling modes, as well as selection of various distribution paths within the vehicle, such as toward the front seat occupants, toward the floor, toward the windshield, and the like.
In a conventional vehicle air handling system, a heater core is mounted in an air duct downstream of an evaporator core. Engine coolant is circulated through the heater core to heat the air. For air conditioning, refrigerant is circulated through the evaporator core. Control of the air temperature is obtained by controlling the flow of air from the evaporator core to the heater core. For maximum cooling, all of the air flow from the evaporator core bypasses the heater core and travels directly to the passenger compartment. Similarly, for maximum heating, all of the air flow from an inactive evaporator core passes through the heater core, where the air is heated before traveling to the passenger compartment. Intermediate these two extremes, bypass flow and flow through the heater core mix to provide air flow to the passenger compartment at an intermediate temperature.
To increase passenger comfort, recent trends have led to multiple, independently selectable temperature zones, referred to as multi-zone temperature control. Individualized temperature control is accomplished by dividing the occupant compartment into zones, the temperature of each zone being controlled by a separate user manipulatable lever or actuator to affect movement of individual blend doors. For example, a dual zone system may be divided into a front driver-side zone and a front passenger-side zone each having independent ducting and temperature control. Similarly, a tri-zone system includes independent ducting and temperature control of three zones, such as front driver-side, front passenger-side, and the rear passenger portion of the vehicle. A quad-zone system includes independent ducting and temperature control of four zones, such as front driver-side, front passenger-side, rear right-side, and a rear left-side of the vehicle.
Many components of the HVAC system, such as the heater core, the evaporator core, ducting, actuators, and the like are located in or near the vehicle instrument panel. Physical space in the vehicle instrument panel has historically been limited, and has become even more limited as new electronic devices and convenience features have been added to the instrument panel.
Typical multi-zone HVAC systems employ a common HVAC assembly that includes a cold or bypass air supply duct that branches to a cold air inlet for each independent zone duct, and a hot air supply duct that branches to a hot air inlet for each independent zone duct. The zone duct is separated from the cold and hot inlets by a blend door that is moveable by an actuator to provide cold, hot, or a blend of hot and cold air into the corresponding zone duct. These additional components such as independent ducting, multiple blend doors, and so forth that are needed to achieve multi-zone temperature control further burdens the already limited physical space in the vehicle.
In a multi-zone HVAC system, each blend door for each zone has a separate actuator. These multiple actuators can be costly and can cause problems in terms of space and access for installation and repair. In one prior art system for a dual-zone configuration, the two actuators are mounted beside one another, with one actuator mounted in line with its corresponding shaft and the other actuator mounted offset from its corresponding shaft. A link mechanism is used to connect this offset actuator with its corresponding shaft. Unfortunately, this link mechanism adds cost and complexity to the system and results in hysteresis, or delayed response of door movement, and inaccuracies of the door position. Inaccurate door movement or delayed door movement directly affects temperature dispersion and air distribution of the HVAC system, thus deteriorating its performance.
Accordingly, what is needed is an actuation system for a door assembly in a multi-zone air handling system that utilizes minimal physical space, and functions with precision to achieve the desired mixing of cooled air, heated air, or a blend of heated and cooled air.
Accordingly, it is an advantage of the present invention that a system is provided for controlling the movement of doors in an air handling system to distribute separate temperature airstreams to multiple zones within a vehicle.
It is another advantage of the present invention that a system for controlling movement is provided that functions accurately to achieve a desired mixing of cooled air, heated air, or a blend of heated and cooled air in each of the zones.
Another advantage of the present invention is that a system is provided for controlling door movement that efficiently utilizes the limited physical space in the vehicle.
Yet another advantage of the present invention is that a system is provided that has a simplified design that is cost effectively manufactured and installed within a vehicle.
The above and other advantages of the present invention are carried out in one form by a system for controlling a first door and a second door. The system includes a first actuator having a first interior passage and a second actuator arranged in line with the first actuator. A first shaft extends from the first actuator and has a second interior passage, the first shaft being configured for communication with the first door, and the first actuator driving the first shaft to cause movement of the first door. A second shaft extends from the second actuator and is directed through the first and second interior passages to exit from an end of the first shaft. The second shaft is configured for communication with the second door, and the second actuator drives the second shaft to cause movement of the second door.
The above and other advantages of the present invention are carried out in another form by a door assembly for use in a heating, ventilation, and air conditioning (HVAC) system of a vehicle. The door assembly includes a first door for controlling airflow through a first opening of the HVAC system depending on a position of the first door, and a second door for controlling airflow through a second opening of the HVAC system depending on a position of the second door. The door assembly further includes an actuation system for controlling movement of the first and second doors. The actuation system includes a first actuator having a first interior passage and a second actuator arranged in line with the first actuator. A first shaft extends from the first actuator and is in communication with the first door. The first shaft has a second interior passage, and the first actuator drives the first shaft to move the first door to control the airflow through the first opening. A second shaft extends from the second actuator and is directed through the first and second interior passages to exit from an end of the first shaft. The second shaft rotates independent from the first shaft within the first and second interior passages, and is in communication with the second door. The second actuator drives the second shaft to move the second door to control the airflow through the second opening.
A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar items throughout the Figures, and:
The present invention entails an actuation system for controlling movement of at least two doors, commonly referred to as blend doors, in an air handling system of a vehicle. The actuation system and a door assembly incorporating the actuation system are particularly suitable for distributing separate temperature airstreams to multiple zones within the vehicle. However, the present invention need not be limited to such an application. Alternatively, the present invention may be incorporated within various systems in which the movement of aligned doors are separately controlled and physical space for such actuation systems is limited.
HVAC system 22 can take a great variety of configurations and operational capabilities well known in the art and not critical to understanding the present invention. Hence, details of HVAC system 22 are not discussed herein for brevity. Rather, the present invention entails the control of a first door 38 that allows passage of first airflow 30 at a selected temperature setting into first zone 26. The present invention further entails the control of a second door 40, positioned beside first door 38, that allows passage of second airflow 34 at an independently selected temperature setting into front second zone 28.
Door assembly 42 includes first door 38 and second door 40 each configured as arcuate members. Door assembly 42 further includes an actuation system 44 for controlling movement of first door 38 within a first frame 46 and second door 40 within a second frame 48 of HVAC system 22.
Each of first and second frames 46 and 48, respectively, includes side members 50, a top span 52, and a bottom span 56. A first opening 58 into first zone duct 32 (
Side members 50 can include grooves 64 for slidably receiving corresponding spindles 66 on each of first and second doors 38 and 40, respectively. A first gear rack 68 is positioned on a concave surface of first door 38 and a second gear rack 70 is positioned on a concave surface of second door 40. Actuation assembly 44 moves first and second doors 38 and 40 via engagement with first and second gear racks 68 and 70 within grooves 64 of respective first and second frames 46 and 48 to control airflow through first opening 58 and second opening 60, respectively.
Referring to
A first shaft 82 extends from a second side 84 of first actuator 72, second side 84 opposing first side 78. First shaft 82 includes a second interior passage 86. A second shaft 88 extends from second actuator 76. Second shaft 88 is directed through first and second interior passages 74 and 86 and exits from an end 90 of first shaft 82 and is rotatable within first and second interior passages 74 and 86.
A first gear 92 is coupled to free end 90 of first shaft 82. First gear 92 has gear teeth 96 configured for meshed engagement with first gear rack 68 of first door 38. Similarly, a second gear 98 is coupled to a second free end 100 of second shaft 88 extending from free end 90 of first shaft 76. Second gear 98 has gear teeth 102 configured for meshed engagement with second gear rack 70 of second door 40.
First actuator 72 drives, i.e., rotates, first shaft 82 to cause movement of first door 38 via the meshed engagement of gear teeth 96 of first gear 92 with first gear rack 68. Similarly, second actuator 76 drives, i.e., rotates, second shaft 88 to cause movement of second door 40 via the meshed engagement of gear teeth 102 of second gear 98 with second gear rack 70. Moreover, second shaft 88 rotates independent from first shaft 82 within first and second interior passages 74 and 86, respectively. Thus, movement of second door 40 is independent of the movement of first door 38.
In a preferred embodiment, communication between first shaft 82 and first door 38 to produce door movement is accomplished through the meshed engagement of first gear 92 with first gear rack 68. Likewise, communication between second shaft 88 and second door 40 to produce door movement is accomplished through the meshed engagement of second gear 98 with second gear rack 70. Those skilled in the art will recognize, however, that alternative components may be utilized in place of the meshed gear and gear rack systems described. above.
The alignment of first and second actuators 72 and 76, respectively, with first and second shafts 82 and 88, respectively, yields a compact actuation system that can more readily fit within the limited space of a vehicle instrumentation panel. Moreover, the in line connection between actuator, shaft, gear, and gear rack enables accurate movement of first and second doors 38 and 40, respectively, without the hysteresis found in prior art actuation systems that use offset actuators and link mechanisms.
Evaporator 104 produces cooled air when engaged and ambient air when disengaged. The air output from evaporator 104 is transferred from evaporator 104 via a cold air supply duct 108. The air in cold air supply duct 108 will be referred to herein as a cool airflow 110 to distinguish it from a hot airflow 112 transferred from heater core 106 via a hot air supply duct 114. Cold air supply duct 108 branches to a cold air inlet 115 for each of first and second doors 38 and 40, respectively, of each door assembly 42. Hot air supply duct 114 also branches to a hot air inlet 117 for each of first and second doors 38 and 40, respectively, of each door assembly 42.
Each of first and second doors 38 and 40 move to block cool airflow 110 transferred from evaporator 104 or hot airflow 112 transferred from heater core 106 into their associated first and second zone ducts 32 and 36, respectively. Each of first and second doors 38 and 40, in certain positions, may additionally allow both cool airflow 110 and hot airflow 112 into their associated first and second zone ducts 32 and 36. Thus, appropriate adjustment of first and second doors 38 and 40 produces only cool airflow 110, only hot airflow 112, or a blended airflow in accordance with a desired temperature setting.
By way of example, first door 38 is adjusted to a position in both which cold and hot air inlets 115 and 117, respectively, are partially open. Consequently, both cool airflow 110 and hot airflow 112 enter first zone duct 32 through first opening 58 to produce airflow 30 at an intermediate temperature. However, second door 40 is adjusted to a position in which hot air inlet 117 is fully blocked. Thus, only cool airflow 110 is allowed to enter second zone duct 36 through second opening 60 to produce second airflow 32 at a maximally cool temperature.
The above discussion concentrates on the use of actuation system 44 with door assembly 42 in a dual-zone climate control system. However, the present invention may be readily adapted for use in a tri-zone or a quad-zone vehicular climate control configuration, discussed below, while achieving the benefits of simplicity of design, accurate door movement, and compact size.
Second actuation subsystem 128 includes a third actuator 130 arranged in line with and longitudinally displaced from first and second actuators 72 and 76 of first actuation subsystem 126. A third shaft 132 extends from third actuator 130. A third gear 134 is coupled to an end of third shaft 132 and is configured for meshed engagement with a third gear rack 136 on a concave surface of third door 122. Third actuator 130 drives, i.e., rotates, third shaft 132 to control movement of third door 122.
In summary, the present invention teaches of an actuation system for controlling the movement of two or more doors in an air handling system to distribute separate temperature airstreams to multiple zones within a vehicle. The alignment of dual actuators and shafts yields a simple and compact design that efficiently utilizes the limited physical space in the vehicle. Moreover, the alignment of dual actuators and shafts eliminates the need for more complex linkage actuation that leads to inaccuracies and hysteresis in door movement. Thus, the actuation system produces accurate and timely movement of at least two doors in a multi-zone climate control system to achieve the desired cooled air, heated air, or a blend of heated and cooled air in each of the zones. In addition, the straightforward design of the actuation system can be readily and cost effectively replicated in other multi-zone applications, such as tri-zone and quad-zone.
Although the preferred embodiments of the invention have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
