Patent Application
20130037252
1. Field of the Invention
The present invention relates to heating, ventilation, and cooling (HVAC) systems, and more particularly, to a smart HVAC system having the capability to detect the presence of an occupant, and modify operation in accordance therewith.
2. Discussion of Prior Art
HVAC systems have long been used to condition an enclosed space fluidly coupled thereto, by pulling air from the space and/or a fresh air supply, treating (heating, cooling, humidifying, dehumidifying, etc.) the air as it flows through one or more components of the system, and then discharging the treated air through one or more air vents or registers back into the space. The air vents typically present covers that function to throw the air as desired. Triggered by a temperature-based sensor, conventional HVAC systems typically produce a set flow rate and operate irrespective of whether an occupant is within the space. By failing to consider occupancy of the space, conventional HVAC systems present inefficiencies, an unnecessarily large carbon footprint, excess wear on component parts, and increased costs associated therewith.
The present invention concerns a smart HVAC system operable to adjustably treat a space based upon occupancy. By selectively closing one or more air vents and/or modifying output when a designated portion of the space is unoccupied, the inventive system is useful for reducing carbon footprint and energy consumption. As such, in an automotive setting, the system is further useful for increasing fuel economy, and/or improving the comfort rating for those portions of the interior cabin having an occupant. Where active materials are incorporated, the invention is also useful for improving packaging options, reduces functionally equivalent mass, noise (both acoustically and with respect to EMF), and complexity/number of moving parts, in comparison to traditional electro-mechanical systems.
In general, the invention comprises an HVAC system fluidly coupled to the space, and including a plurality of vents, a controller, and a plurality of occupant detection sensors. Each vent is fluidly coupled to a generally separate portion of the space. The controller is communicatively coupled to the HVAC system and operable to control fluid flow between the space and vents, on an individual basis. The occupant detection sensors are operable to detect a presence of an occupant within each portion of the space, and communicatively coupled to the controller, so as to inform the controller of any presence. Thus, the HVAC system, controller, and sensors are cooperatively configured to deliver treated fluid to at least one of the portions only when an occupant is detected therein.
Other aspects and advantages of the present invention, including preferred configurations and methods utilizing shape memory wire actuators, and a multi-louver cover, latching and overload protection mechanisms, and more will be apparent from the following detailed description of the preferred embodiment(s) and the accompanying drawing figures.
A preferred embodiment(s) of the invention is described in detail below with reference to the attached drawing figures:
a is a plan view of a vehicle defining an interior cabin demarking driver, front, and rear zones, and including an HVAC system presenting a plurality of vents serving the zones, occupant detection sensors disposed in each zone and communicatively coupled to the HVAC system, wherein occupants are present throughout and the HVAC system fully serves each zone, in accordance with a preferred embodiment of the invention; and
b is a plan view of the vehicle shown in
The present invention concerns a smart HVAC system 10 operable to detect the presence of an occupant 12 within a space 14 to be treated, and autonomously modify its output and/or configuration accordingly. 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 from the scope of the invention. The system 10 is described and illustrated (
The inventive system 10 includes an HVAC system 16, a controller 18 communicatively coupled to the HVAC system 16 and having stored thereupon for processing an actuation module, and at least one sensor 20 operable to detect the presence of an occupant 12 and communicatively coupled to the controller 18 (
In
More particularly, an autonomously adjustable cover 26 is connected and preferably sealed to each vent 22 at the outlet. For example, to save space, the cover 26 may present a multi-louver configuration, wherein a plurality of louvers 26a are inter-linked, and conjunctively actuated, so as to be caused to move congruently and in unison (
In the preferred embodiment, the controller 18 is also communicatively coupled to a blower 24 having a variable drive. The blower 24 as such, is operable to deliver variable output flow rates. In an automotive embodiment, for example, the HVAC system 16 may include first and second blowers 24 (
In a preferred embodiment, active material actuation is used, among other ways, to shift the cover 26 to the opened and/or closed conditions, or sense the occupant 12 more efficiently than conventional actuators and sensors, as previously presented. An active material actuator 28 or sensor 20 may either individually or in combination with traditional means of actuation provide a separate function or assist on the same function (such as to boost the force level beyond that which could be provided by the traditional actuator when required).
As used herein the term “active material” shall be afforded its ordinary meaning as understood by those of ordinary skill in the art, and includes any material or composite that exhibits a reversible change in a fundamental (e.g., chemical or intrinsic physical) property, when exposed to an external signal source. Thus, active materials shall include those compositions that can exhibit a change in stiffness properties, shape and/or dimensions in response to the activation signal, which can take the type for different active materials, of electrical, magnetic, thermal and like fields. Suitable active materials for use with the present invention include those that can be used as actuators and/or to sense the presence of an occupant, including but not limited to shape memory alloys (SMA), electroactive polymers (EAP), ferromagnetic SMA's, and piezoelectric composites, as further described below, as well as, shape memory polymers (SMP), shape memory ceramics, electrorheological (ER) compositions, magnetorheological (MR) compositions, dielectric elastomers, and other recognized active materials.
SMA in wire form, for example, may be used to drive the cover 26 to one of the opened and closed conditions by taking advantage of its shape memory characteristics, wherein the term “wire” shall be construed broadly to include other equivalent tensile configurations, such as strips, braids, cables, chains, etc. More particularly, an SMA wire 28 may be coupled to the louvers 26a (
In
Where a two-way shape memory is provided, the wire 28 functions to return the cover 26 to the previous condition, when deactivated; otherwise, a biasing mechanism 30 is added to the system 10 and functions to return the louvers 26a to the normal (e.g., opened for driver portion, and closed for front-passenger, and rear portions) condition, when the wire 28 is deactivated. For example, the links between louvers 26a may present elastic members that work to pull the cover 26 shut (
A latching mechanism 32 is preferably used to hold the cover 26 in the achieved condition, when the active material element 28 is deactivated. For example, a pawl pivotally coupled to adjacent fixed structure may be configured to engage a prong fixedly attached to the cover 26, only when the cover 26 achieves the opened condition (
Finally, the SMA wire actuator 28, in
With respect to the sensor 20, active material actuation may be used to sense and/or inform the controller 18 of the presence. For example, a piezoelectric load cell may be disposed within a floor or seat, so as to receive the weight of an occupant 12, when entering the space 14. More particularly, the piezoelectric element may be used to convert a change in pressure to electricity, and cause a signal to be sent to the controller 18 or HVAC system 16 directly (e.g., to activate the actuator 28 of the cover 26), when compressed by the occupant 12. A detailed discussion of piezoelectric composites and their function is provided below.
In another example, an SMA wire may be positioned and oriented to receive the weight of the occupant 12, so as to undergo a change in stress, when the occupant 12 enters the space 14; here, it is appreciated that the electrical resistance of an SMA element is directly proportional to the stress load it sustains. To that end, and as shown in
Shape memory alloys (SMA's) generally refer to a group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to an appropriate thermal stimulus. Shape memory alloys are capable of undergoing phase transitions in which their yield strength, stiffness, dimension and/or shape are altered as a function of temperature. The term “yield strength” refers to the stress at which a material exhibits a specified deviation from proportionality of stress and strain. Generally, in the low temperature, or martensite phase, shape memory alloys can be plastically deformed and upon exposure to some higher temperature will transform to an austenite phase, or parent phase, returning to their shape prior to the deformation.
Shape memory alloys exist in several different temperature-dependent phases. The most commonly utilized of these phases are the so-called martensite and austenite phases discussed above. In the following discussion, the martensite phase generally refers to the more deformable, lower temperature phase whereas the austenite phase generally refers to the more rigid, higher temperature phase. When the shape memory alloy is in the martensite phase and is heated, it begins to change into the austenite phase. The temperature at which this phenomenon starts is often referred to as austenite start temperature (As). The temperature at which this phenomenon is complete is called the austenite finish temperature (Af). Activation may be effected by temperature change caused by electric current signalization (e.g, through electric leads (not shown) connected to the vehicle charging system and battery), or other physical or chemical conversion.
When the shape memory alloy is in the austenite phase and is cooled, it begins to change into the martensite phase, and the temperature at which this phenomenon starts is referred to as the martensite start temperature (Ms). The temperature at which austenite finishes transforming to martensite is called the martensite finish temperature (Mf). Generally, the shape memory alloys are softer and more easily deformable in their martensitic phase and are harder, stiffer, and/or more rigid in the austenitic phase. In view of the foregoing, a suitable activation signal for use with shape memory alloys is a thermal activation signal having a magnitude to cause transformations between the martensite and austenite phases.
Shape memory alloys can exhibit a one-way shape memory effect, an intrinsic two-way effect, or an extrinsic two-way shape memory effect depending on the alloy composition and processing history. Annealed shape memory alloys typically only exhibit the one-way shape memory effect. Sufficient heating subsequent to low-temperature deformation of the shape memory material will induce the martensite to austenite type transition, and the material will recover the original, annealed shape. Hence, one-way shape memory effects are only observed upon heating. Active materials comprising shape memory alloy compositions that exhibit one-way memory effects do not automatically reform, and will likely require an external mechanical force to reform the shape.
Intrinsic and extrinsic two-way shape memory materials are characterized by a shape transition both upon heating from the martensite phase to the austenite phase, as well as an additional shape transition upon cooling from the austenite phase back to the martensite phase. Active materials that exhibit an intrinsic shape memory effect are fabricated from a shape memory alloy composition that will cause the active materials to automatically reform themselves as a result of the above noted phase transformations. Intrinsic two-way shape memory behavior must be induced in the shape memory material through processing. Such procedures include extreme deformation of the material while in the martensite phase, heating-cooling under constraint or load, or surface modification such as laser annealing, polishing, or shot-peening. Once the material has been trained to exhibit the two-way shape memory effect, the shape change between the low and high temperature states is generally reversible and persists through a high number of thermal cycles. In contrast, active materials that exhibit the extrinsic two-way shape memory effects are composite or multi-component materials that combine a shape memory alloy composition that exhibits a one-way effect with another element that provides a restoring force to reform the original shape.
The temperature at which the shape memory alloy remembers its high temperature form when heated can be adjusted by slight changes in the composition of the alloy and through heat treatment. In nickel-titanium shape memory alloys, for instance, it can be changed from above about 100° C. to below about −100° C. The shape recovery process occurs over a range of just a few degrees and the start or finish of the transformation can be controlled to within a degree or two depending on the desired application and alloy composition. The mechanical properties of the shape memory alloy vary greatly over the temperature range spanning their transformation, typically providing the system with shape memory effects, super-elastic effects, and high damping capacity.
Suitable shape memory alloy materials include, without limitation, nickel-titanium based alloys, indium-titanium based alloys, nickel-aluminum based alloys, nickel-gallium based alloys, copper based alloys (e.g., copper-zinc alloys, copper-aluminum alloys, copper-gold, and copper-tin alloys), gold-cadmium based alloys, silver-cadmium based alloys, indium-cadmium based alloys, manganese-copper based alloys, iron-platinum based alloys, iron-platinum based alloys, iron-palladium based alloys, and the like. The alloys can be binary, ternary, or any higher order so long as the alloy composition exhibits a shape memory effect, e.g., change in shape orientation, damping capacity, and the like.
It is appreciated that SMA's exhibit a modulus increase of 2.5 times and a dimensional change of up to 8% (depending on the amount of pre-strain) when heated above their Martensite to Austenite phase transition temperature. It is appreciated that thermally induced SMA phase changes are one-way so that a biasing force return mechanism (such as a spring) would be required to return the SMA to its starting configuration once the applied field is removed. Joule heating can be used to make the entire system electronically controllable. Stress induced phase changes in SMA are, however, two way by nature. Application of sufficient stress when an SMA is in its Austenitic phase will cause it to change to its lower modulus Martensitic phase in which it can exhibit up to 8% of “superelastic” deformation. Removal of the applied stress will cause the SMA to switch back to its Austenitic phase in so doing recovering its starting shape and higher modulus.
Ferromagnetic SMA's (FSMA's), which are a sub-class of SMAs, may also be used in the present invention. These materials behave like conportional SMA materials that have a stress or thermally induced phase transformation between martensite and austenite. Additionally FSMA's are ferromagnetic and have strong magnetocrystalline anisotropy, which permit an external magnetic field to influence the orientation/fraction of field aligned martensitic variants. When the magnetic field is removed, the material may exhibit complete two-way, partial two-way or one-way shape memory. For partial or one-way shape memory, an external stimulus, temperature, magnetic field or stress may permit the material to return to its starting state. Perfect two-way shape memory may be used for proportional control with continuous power supplied. External magnetic fields may be produced by soft-magnetic core electromagnets in automotive applications, though a pair of Helmholtz coils may also be used for fast response.
Suitable piezoelectric materials include, but are not intended to be limited to, inorganic compounds, organic compounds, and metals. With regard to organic materials, all of the polymeric materials with non-centrosymmetric structure and large dipole moment group(s) on the main chain or on the side-chain, or on both chains within the molecules, can be used as suitable candidates for the piezoelectric film. Exemplary polymers include, for example, but are not limited to, poly(sodium 4-styrenesulfonate), poly (poly(vinylamine)backbone azo chromophore), and their derivatives; polyfluorocarbons, including polyvinylidenefluoride, its co-polymer vinylidene fluoride (“VDF”), co-trifluoroethylene, and their derivatives; polychlorocarbons, including poly(vinyl chloride), polyvinylidene chloride, and their derivatives; polyacrylonitriles, and their derivatives; polycarboxylic acids, including poly(methacrylic acid), and their derivatives; polyureas, and their derivatives; polyurethanes, and their derivatives; bio-molecules such as poly-L-lactic acids and their derivatives, and cell membrane proteins, as well as phosphate bio-molecules such as phosphodilipids; polyanilines and their derivatives, and all of the derivatives of tetramines; polyamides including aromatic polyamides and polyimides, including Kapton and polyetherimide, and their derivatives; all of the membrane polymers; poly(N-vinyl pyrrolidone) (PVP) homopolymer, and its derivatives, and random PVP-co-vinyl acetate copolymers; and all of the aromatic polymers with dipole moment groups in the main-chain or side-chains, or in both the main-chain and the side-chains, and mixtures thereof.
Piezoelectric materials can also comprise metals selected from the group consisting of lead, antimony, manganese, tantalum, zirconium, niobium, lanthanum, platinum, palladium, nickel, tungsten, aluminum, strontium, titanium, barium, calcium, chromium, silver, iron, silicon, copper, alloys comprising at least one of the foregoing metals, and oxides comprising at least one of the foregoing metals. Suitable metal oxides include SiO2, Al2O3, ZrO2, TiO2, SrTiO3, PbTiO3, BaTiO3, FeO3, Fe3O4, ZnO, and mixtures thereof and Group VIA and IIB compounds, such as CdSe, CdS, GaAs, AgCaSe2, ZnSe, GaP, InP, ZnS, and mixtures thereof. Preferably, the piezoelectric material is selected from the group consisting of polyvinylidene fluoride, lead zirconate titanate, and barium titanate, and mixtures thereof.
Electroactive polymers include those polymeric materials that exhibit piezoelectric, pyroelectric, or electrostrictive properties in response to electrical or mechanical fields. An example of an electrostrictive-grafted elastomer with a piezoelectric poly(vinylidene fluoride-trifluoro-ethylene) copolymer. This combination has the ability to produce a varied amount of ferroelectric-electrostrictive, molecular composite systems. These may be operated as a piezoelectric sensor or even an electrostrictive actuator.
Materials suitable for use as an electroactive polymer may include any substantially insulating polymer or rubber (or combination thereof) that deforms in response to an electrostatic force or whose deformation results in a change in electric field. Exemplary materials suitable for use as a pre-strained polymer include silicone elastomers, acrylic elastomers, polyurethanes, thermoplastic elastomers, copolymers comprising PVDF, pressure-sensitive adhesives, fluoroelastomers, polymers comprising silicone and acrylic moieties, and the like. Polymers comprising silicone and acrylic moieties may include copolymers comprising silicone and acrylic moieties, polymer blends comprising a silicone elastomer and an acrylic elastomer, for example.
Materials used as an electroactive polymer may be selected based on one or more material properties such as a high electrical breakdown strength, a low modulus of elasticity (for large or small deformations), a high dielectric constant, and the like. In one embodiment, the polymer is selected such that is has an elastic modulus at most about 100 MPa. In another embodiment, the polymer is selected such that is has a maximum actuation pressure between about 0.05 MPa and about 10 MPa, and preferably between about 0.3 MPa and about 3 MPa. In another embodiment, the polymer is selected such that is has a dielectric constant between about 2 and about 20, and preferably between about 2.5 and about 12. The present disclosure is not intended to be limited to these ranges. Ideally, materials with a higher dielectric constant than the ranges given above would be desirable if the materials had both a high dielectric constant and a high dielectric strength. In many cases, electroactive polymers may be fabricated and implemented as thin films. Thicknesses suitable for these thin films may be below 50 micrometers.
Ranges disclosed herein are inclusive and combinable (e.g., ranges of “up to about 25 wt %, or, more specifically, about 5 wt % to about 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “about 5 wt % to about 25 wt %,” etc.). “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or imventance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The modifier “about” used in connection with a quantity is inclusive of the state value and has the meaning dictated by context, (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the colorant(s) includes one or more colorants). Reference throughout the specification to “one embodiment”, “another embodiment”, “an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.
Suitable algorithms, processing capability, and sensor inputs are well within the skill of those in the art in view of this disclosure. This invention has been described with reference to exemplary embodiments. 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 a 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.
