Patent Application
20080185059
1. Field of the Invention
The invention relates to a climate control system also commonly referred to as an HVAC system (heating, ventilation, and air conditioning) for a vehicle and more specifically to a valve assembly for controlling airflow through an outlet of the climate control system.
2. Description of the Prior Art
Conventional heating, ventilation and air conditioning (HVAC) systems for vehicles generally include a housing, an evaporator, a heater core having a housing, an evaporator assembly coupled to the housing, an evaporator, a heater core, an air inlet, a fan and various doors or mode valves for controlling the volume and direction of air flow and generating outlet air of a desired volume and temperature. Together these components receive, temper and direct the flow of forced air through several outlets or vents in the vehicle. The outlets through which the forced air ultimately exits are determined by the various doors which move between open and closed positions and cause air flow to be forced in one direction or another or a combination of both. Air may be directed to various areas of the car depending on the state of the mode valves. For example, air may be forced through outlets directed at the windshield in a defrost or defog mode, or through outlets directed at mid-height level in an air-conditioning mode, or to lower outlets directed to the floor in a heat mode, or various combinations thereof. Generally, designs have been utilized in which the housing has a plurality of outlets each having a periphery. More recently, the housing is defined by two oppositely facing outlets. A motor or mechanism is attached to a shaft that is rotatably supported by the housing outside the peripheries of the outlets. A rotary plate valve is disposed about the shaft and is movable to cover or block air from exiting the outlets in a closed position and uncover or unblock the outlets to permit air to exit the housing in an open position. The plate valve's periphery is connected to the shaft and the plate valve is covered with material which complies with the interior of the housing in order to form an air seal. This material generally is made from a compressible cellular foam or molded thermoset rubber that forms a wiper. As the shaft rotates, the plate valve rotates with the shaft so that the foam or rubber attached to the plate valve seals the outlets.
These rotary plate valves require the plate and its seal to be in sliding contact with the housing when alternating between the open and closed positions. Such a sliding valve requires relatively high contact pressure in order to compress the foam or deform the rubber wiper in order to achieve a desired seal.
Furthermore, these rotary plate valves rely on a torque limited motor to rotate the shaft end either directly or remotely via a cam, link and lever in order to move the valve plate to the open and closed positions. When the contact pressure is too high for the motor to overcome, the plate valve can become immobilized in an undesired position and may result in failure of the motor. HVAC systems having these rotary plate valves do not have a means to direct the cold air from the evaporator core and hot air from the heater towards the outlet in order to achieve a desired outlet temperature while in an open position. Additionally, these rotary plate valves do not have a means to meter a portion of these airstreams while in an intermittent position between open and closed. These intermittent positions are desired in order to achieve the proper air balance between the various outlets such as the lower outlets directed to the floor in a heat mode.
Examples of rotary valves in HVAC systems are included in U.S. Pat. No. 4,683,913 to Hoffman et al. and U.S. Pat. No. 5,009,392 to Ostrand.
Hoffman et al. teach a rotary valve for sealing outlets defined by a curved surface. The air valve has a radius of curvature measured from an axis which is offset from that of the radius of curvature for the surface defining the outlets being sealed. This valve's plate and sealing surface which cover or uncover an outlet are parallel with the axis of the shaft and as such is only able to seal an outlet that is located parallel with the axis of the shaft. The contact pressure is therefore high when the valve is in a closed position and diminishes to zero after the valve is rotated to an open position.
Although the prior art provides valves which move between open and closed positions, there remains a need for a valve that does not produce high frictional loads while simultaneously aiding in directing air flow through the outlet of the housing. Furthermore, there also remains a need for a valve that can direct the cold air from the evaporator core and hot air from the heater towards the outlet in order to achieve a desired outlet temperature and can meter a portion of these airstreams while in an intermittent position between open and closed. Additionally, there remains a need for a rotary valve whose plate and sealing surface is perpendicular to the shaft.
The invention provides such an assembly for controlling air flow in an HVAC system wherein the rotatable shaft has a threaded section. The interior surface of the plate valve is threaded and is in threaded engagement with the threaded section of the shaft for moving the plate valve axially away from the outlet in response to rotation of the shaft in a first direction and moving the first plate valve axially toward the outlet in response to rotation of the shaft in a second direction opposite to the first direction while the plate valve is kept from rotating due to its relative engagement with the outlet.
The invention provides a valve which uses linear valve motion in order to seal an outlet with a uniform seal about the periphery. Moreover, the linear motion eliminates the friction related to sliding described in the prior art and thereby reduces the risk of failure or fatigue. Additionally, the invention structurally baffles a hot or cold airstream towards the outlet to facilitate air mixing in order to achieve the desired outlet temperature.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
A plurality of different embodiments of the invention are shown in the Figures of the application. Similar features are shown in the various embodiments of the invention. Similar features are structured similarly, operate similarly, and/or have the same function unless otherwise indicated by the drawings or this specification. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment unless otherwise indicated by the drawings or this specification.
A climate control or HVAC system 20 can be disposed in a vehicle to control conditions associated with air inside a passenger compartment of a vehicle. The exemplary climate control system 20 includes a blower 22 for blowing air through the housing 24 and a plurality of heat exchangers 26 for heating and cooling the air in the housing 24, as shown in
Referring to
A shaft 40 is rotatably supported by the housing 24 outside the peripheries 30, 34 of the outlets 28, 32 and extends along an axis A. The shaft 40 extends between and perpendicular to the peripheries 30, 34 of the outlets 28, 32.
The assembly 20 includes a first plate valve 42 for covering the first outer periphery 30 of the first outlet 28 in a closed position and axially movable to an open position.
A second plate valve 50 is included for covering the second outer periphery 34 of the second outlet 32 in a closed position and movable to an open position. The second valve 50 includes a second bushing 52 defining a second interior surface 54 surrounding the shaft 40. The second valve 50 also includes a second plate extending radially from the second bushing 52 in a fan-like shape for sealing the second periphery 34 of the second outlet 32. A second reinforcing web 56 interconnects the second bushing 52 and the second plate for reinforcing the second plate on the second bushing 52.
The assembly 20 is distinguished by the shaft 40 having oppositely threaded first and second sections 58, 60 disposed at opposite ends of the shaft 40 as best shown in
The assembly 20 includes a guide 62, generally indicated, for limiting rotation of the valves 42, 50 relative to the axis A in response to rotation of the shaft 40. The first valve 42 may include a first guide plate 64 and the second valve 50 may include a second guide plate 66 to define the guide 62.
As best shown in
While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing form the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
