BACKGROUND OF INVENTION
[0001] This invention relates to controlling residential forced air HVAC systems, specifically an improved zone climate control system for installation in an existing HVAC system that is less expensive , easier to install, and provides more utility than the prior art, such that a plurality of rooms in the residence each have independent temperature regulation according to predetermined temperature schedules and locally entered temperature commands, and such that the air in each said room is heated or cooled according to the occupancy and the activity in said room, whereby improving the comfort of the occupants and reducing the energy used to heat or cool the residence.
[0002] The majority of single-family houses in the United States have forced air central heating systems. Many of these also have air conditioners that use the same air distribution system. These heating, ventilation, and air conditioning (HVAC) systems are typically controlled by a single, centrally located thermostat. The thermostat controls the HVAC equipment to maintain a constant temperature at the thermometer.
[0003] The temperatures in other rooms of the house are not actively controlled, so the temperatures in different rooms can differ by many degrees from the temperature at the thermostat.
[0004] Manually adjusting the airflow to each room is the primary method available to control the temperature away from the thermostat. However, the temperatures away from the thermostat depend on many dynamic factors such as the season (heating or cooling), the outside temperature, radiation heating and cooling through windows, and the activities of people and equipment in the rooms. The desired temperature also depends on the activity of the occupant, for example lower temperatures for sleeping and higher temperatures for relaxing. Maintaining comfortable temperatures requires constant adjustment, or may not be possible.
[0005] These temperature control problems are well known to HVAC suppliers, installers, and house occupants. Zone control systems have been developed to improve temperature control. Typically, a small number of thermostats are located in different areas of the house, and a small number of mechanized airflow dampers are placed in the air distribution ducts. A control unit dynamically controls the HVAC equipment and the airflow to simultaneously control the temperatures at each thermostat. These conventional systems are difficult to retro fit and provide limited function and benefit.
[0006] They are provided by several companies such as Honeywell, 1071 Columbia Road, Morristown, N.J. 07962, Carrier One Carrier Place, Farmington, Conn. 06034; Jackson Systems, LLC100 E. Thompson Rd., Indianapolis, Ind. 46227; Arzel Zoning Technology, lnc.4801 Commerce Parkway, Cleveland, Ohio 44128; Duro Dyne, 81 Spence Street, Bay Shore, N.Y. 11706; and EWC Controls, Inc. 385 Highway 33, Englishtown, N.J. 07726.
[0007] With only a few zones, there can still be significant temperature variations from room-to-room within a zone. A few systems have proposed thermostats for each room and airflow control devices for each air vent, but no practical solution for easy retrofit has been disclosed. As the number of independent zones increases it becomes more complex to specify appropriate setting for each zone while providing convenient centralized and remote control. Typical residential HVAC systems are designed to produce one fixed rate of heating and cooling, so adapting the existing systems to provide heating or cooling for only one or two rooms is difficult. These systems do provided methods to measure energy usage or provide information to help reduce energy use. They have been widely adopted because they are expensive, difficult and intrusive to install in most existing houses, and provide limited utility and benefit compared to their cost and inconvenience.
[0008] U.S. Pat. No. 5,348,078 issued Sep. 30, 1994 and U.S. Pat. No. 5,449,319 issued, Sep. 12, 1995 to Dushane et. al describes a retrofit room-by-room zone control system for residential forced air HVAC systems that uses complex electrically activated airflow control devices at each air vent. The devices are mechanically complex, each with a radio receiver, servo motor, and multiple mechanical louvers. The devices are powered by batteries that are recharged by a generator powered by airflow through the air vent. Another embodiment is described that uses wires connected to a central control unit to control the airflow control devices, adding complexity to the installation process. The airflow control devices replace the existing air grills, so the installation is visible and multiple sizes and shapes of airflow control devices are needed to accommodate the variety of air vent found in houses. The devices are expensive and have no shared mechanisms for control or activation to reduce the cost of the multiple devices required. The preferred embodiment uses household power wiring for communications between the thermostats and the central control, requiring visible wires from a power outlet to the thermostat. A cited advantage of the system is it does not have sensors inside the ducts, so the system cannot make control decisions based on plenum pressure or plenum pressure, therefore excessive noise and temperatures may occur for some settings of the airflow control devices. The thermostats and common controller have complex interfaces with limited functionality making the system difficult to use.
[0009] U.S. Pat. No. 5,704,545 issued Jan. 6, 1998 to Sweitzer describes another zone system where the airflow control devices are louvers actuated by a local electromechanical mechanism. This invention requires modification to the air ducts and connecting wires from the airflow control devices to the common controlling device. This system is expensive and difficult to retrofit.
[0010] U.S. Pat. No. 4,545,524 issued Oct. 8, 1985, U.S. Pat. No. 4,600,144 issued Jul. 15, 1986, U.S. Pat. No. 4,742,956 issued May 10, 1988, and U.S. Pat. No. 5,170,986 issued Dec. 15, 1992 to Zelczer, et al. describe a variety of inflatable bladders used as airflow control devices in air ducts. All of these are adapted for mounting in a way that requires access to the air ducts for cutting holes and inserting devices into the duct, and for the controlling air tube to pass from the inside of the air duct to the outside of the duct for passage to the device that provides the air for the bladders. These airflow control devices do not provide a way for non-intrusive installation.
[0011] U.S. Pat. No. 4,522,116 issued Jun. 11, 1985, U.S. Pat. No. 4,662,269 issued May 5, 1987, U.S. Pat. No. 4,783,045 issued Nov. 8, 1988, and U.S. Pat. No. 5,016,856 issued May 21, 1991 to Tartaglino describes a series of inflatable bladders of different shapes and control methods. The disclosed control methods relate to the air pressure and vacuum used to inflated and deflate the bladders. The bladder shapes are novel but different from those used in the present invention.
[0012] U.S. Pat. No. 5,234,374 issued Aug. 10, 1993 to Hyzyk, et al. describes an inflatable bladder used as an airflow control device installed inside an air duct at an air vent. The bladder is inflated by a small blower also mounted in the air vent and powered by a battery. It receives control signals from a separate thermostat located in the room. This devices uses substantial power and battery life is limited. Since the blower for inflating the bladder is located at the air vent, noise from the blow is a problem which the inventor provides a muffler to help control. Each bladder is an independent unit and there is no sharing of components for controlling or powering, so there are no savings when many airflow devices are used in a zone control system. The device does provide a practical solution for an providing centrally controllable airflow devices for each air vent in a house.
[0013] U.S. Pat. No. 5,772,501 issued Jun. 30, 1998 to Merry, et al. describes a system for selectively circulating unconditioned air for a predetermined time to provide fresh air. The system uses conventional airflow control devices installed in the air ducts and the system does not use temperature difference to control circulation. This system is difficult to retrofit and does not exploit selective circulation to equalize temperatures.
[0014] U.S. Pat. No. 5,024,265 issued Jun. 18, 1991 to Buchholz, et al. describes a zone control system with conventional thermostats located in each zone. This system teaches one method for distributing conditioned air to zones based dependent on the zone that has the greatest need for conditioning. However, the thermostats make on-off request for conditioning based on local set points, so the system must deduce need based on the duty cycle of on-off requests. The control system does not have access to the actual temperature of in the zone nor any other characteristic of the zone such as thermal resistance or thermal capacity. This system is not practically adaptable to a residential system.
[0015] U.S. Pat. No. 5,341,988 issued Aug. 30, 1994 to Rein, et al. describes a hierarchical wireless control system for zone control. This system is designed for large commercial building and is no practically adaptable for retrofit to a house.
[0016] U.S. Pat. No. 6,116,512 issued Sep. 12, 2000 to Dushane, et al. describes a wireless thermostat system where each wireless device has a number of programming functions for setting temperature and time schedules. Each thermostat function must be programmed at each device and there is no method to share programming effort or information between devices. The cost and complexity of a full functioning thermostat is duplicated for each device. The number of input buttons and the display capabilities at each devices is limited so programming is complex and functionality is limited.
[0017] U.S. Pat. No. 6,213,404 issued Apr. 10, 2001 to Dushane, et al. describes another wireless thermostat device comprising battery wireless thermometers reporting to a wireless thermostat. This device provides no method for entering commands at the wireless thermometer and uses a fixed slow rate of reporting the temperature stored at the wireless thermometer. The system is not adapted for use with a zone control system.
[0018] U.S. Pat. No. 5,224,648 issued Jul. 6, 1993 to Simon, et al. describes a wireless HVAC system using spread spectrum radio transmission technology. The control architecture requires reliable two way communication and is not practical for battery powered operation. The describes system cannot operate with infrequent and unreliable transmissions from the wireless thermometers and is not adaptable for low cost installation into existing residential HVAC systems.
[0019] U.S. Pat. No. 5,711,480 issued Jan. 27, 1998 to Zepke, et al. describes and claims using wireless SAW transmitters and receivers in an HVAC system. The patent teaches only the replacement of other wireless technology such as described in previously cited U.S. Pat. No. 5,224,648 with SAW based wireless technology and does not add to the art of retrofit zone climate control.
[0020] U.S. Pat. No. 5,782,296 issued Jul. 21, 1998 to Mehta describes a thermostat that has several 24-hour temperature schedules that are specified by entering a complex sequence of commands using a small number of buttons. The display can only display a small portion of the data of each temperature schedule at one time. Using this type of interface to program multiple temperature schedules for multiple zones would take great effort and is complex. This device is not practically adaptable for use in a room-by-room zone control system for a house.
[0021] U.S. Pat. No. 4,819,714 issued Apr. 11, 1989 to Otsuka, et al. describes a device for specifying multiple temperature schedule for multiple thermostats. It uses a display and as set of button designed specifically for this purpose. The system is designed for use with programmable thermostats that can be set locally or the device can program the thermostats with data entered at the central control. This device provides only a way of programming each thermostat wit a common device is not adapted to controlling rooms within a house, a group of room, or the entire house with a single temperature schedule. It provides no means for saving temperature schedules or grouping temperature schedules into temperature programs for the entire house. The device is not practical for adapting to a residential house.
[0022] U.S. Pat. No. 5,949,232 issued Sep. 7, 1999 to Parlante describes a method for measuring the relative energy used by each unit of many units served by a single furnace base on the accumulated time each unit draws energy. The method prorate the total based on time and does not account for different rates of energy use by each unit. The method requires individual timers for each unit and a method for communicating times to a central location. The method does not provide accurate results when each unit draws energy at different rates from the common source, and is not adaptable to a residential zone controlled forced air HVAC system.
[0023] U.S. Pat. No. 6,349,883 issued Feb. 26, 2002 to Simmons, et al. describes a control system for a set of zones that draw energy form a common supply. The system claims to save energy using occupant sensors and parameters entered locally in each zone to request conditioning only when the zone is occupied. The system does not a centralized way to specify and control the zones as groups or as entire house, and the system is practical for residential retrofit or use.
[0024] U.S. Pat. No. 5,884,384 issued Mar. 23, 1999 to Griffioen describes a method for installing a tube inside another tube using a fluid under pressure. This method is not adaptable to air ducts because air duct are variable size, have irregular bends and corners, and are designed to withstand very small pressure differences.
[0025] The prior art individually or in combination does not provide a practical means for providing a zone control system or retrofit to existing HVAC residential buildings and homes. Individual components needed for each room have replicated components that could be shared to reduce cost. Installation of the components requires access and or modification to existing air ducts and changing or modifying object visible to the occupant of the rooms. The control systems are complex and difficult to control so the occupants are not able to get full benefit from zone control. The control systems provide no information about the energy used to condition each room or predictions that help the occupants make informed decisions about comfort versus energy savings. Prior systems provide no means for diagnosing energy use to identify HVAC equipment of building problems that can be cost effectively repaired.
DETAILED DESCRIPTION
[0061] FIG. 1 is a block diagram of a typical forced air system. The existing central HVAC unit 10 is typically comprised of a return air plenum 11 , a blower 12 , a furnace 13 , an optional heat exchanger for air conditioning 14 , and a conditioned air plenum 15 . The configuration shown is called “down flow” because the air flows down. Other possible configurations include “up flow” and “horizontal flow”. A network of air duct trunks 16 and air duct branches 17 connect from the conditioned air plenum 15 to each air vent 18 in room A, room B, and room C. Each air vent is covered by an air grill 31 . Although only three rooms are represented in FIG. 1 , the invention is designed for larger houses with many rooms and at least one air vent in each room. The conditioned air forced into each room is typically returned to the central HVAC unit 10 through one or more common return air vents 19 located in central areas. Air flows through the air return duct 20 into the return plenum 11 .
[0062] The existing thermostat 21 is connected by a multi-conductor cable 73 to the existing HVAC controller 22 that switches power to the blower, furnace and air conditioner. The existing thermostat 21 commands the blower and furnace or blower and air conditioner to provide conditioned air to cause the temperature at thermostat to move toward the temperature set at the existing thermostat 21 .
[0063] FIG. 1 is only representative of many possible configurations of forced air HVAC systems found in existing houses. For example, the air conditioner can be replaced by a heat pump that can provide both heating and cooling, eliminating the furnace. In some climates, a heat pump is used in combination with a furnace. The present invention can accommodate the different configurations found in most existing houses.
Overview of the System
[0064] FIG. 2 is a block diagram of the present invention installed in an existing forced air HVAC system as shown in FIG. 1 . The airflow through each vent is controlled by an airtight bladder 30 mounted behind the air grill 31 covering the air vent 18 . The bladder is either fully inflated or deflated while the blower 12 is forcing air through the air duct 17 . A small air tube 32 (˜0.25″ OD) is pulled through the existing air ducts to connect each bladder to one air valve of a plurality of servo controlled air valves 40 mounted on the side of the conditioned air plenum 15 . There is one air valve for each bladder. A small air pump in air pump enclosure 50 provides a source of low-pressure (˜1 psi) compressed air and vacuum at a rate of ˜1.5 cubic feet per minute. The pressure air tube 51 connects the pressurized air to the air valves 40 . The vacuum air tube 52 connects the vacuum to the air valves 40 . The air pump enclosure 50 also contains a 5V power supply and control circuit for the air pump. The AC power cord 54 connects the system to 110V AC power. The power and control cable 55 connect the 5V power supply to the control processor and servo controlled air valves and connects the control processor 60 to the circuit that controls the air pump. The control processor 60 controls the servos in 40 to set each air valve to one of two positions. The first position connects the compressed air to the air tube so that the bladder inflates. The second position connects the vacuum to the air tube so that the bladder deflates.
[0065] A wireless thermometer 70 is placed in each room in the house. All thermometers transmit on a shared radio frequency of 433 Mhz packets of digital information that encode 32-bit digital messages. A digital message includes a unique thermometer identification number, the temperature, and command data. Two or more thermometers can transmit at the same time, causing errors in the data. To detect errors, the 32-bit digital message is encoded twice in the packet. The radio receiver 71 decodes the messages from all the thermometers 70 , discards packets that have errors, and generates messages that are communicated by serial data link 72 to the control processor 60 . The radio receiver 71 can be located away from the shielding effects of the HVAC equipment if necessary to ensure reception from all thermometers.
[0066] The control processor 60 is connected to the existing HVAC controller 22 by the existing HVAC controller connection 74 . The control processor 60 interface circuit uses the same signals as the existing thermostat 21 to control the HVAC equipment. The existing thermostat connection 73 is also connected to the control processor 60 interface circuit that includes a manual two position switch. In the first switch position, the HVAC controller 22 is connected to the control processor 60 . In the second switch position, the HVAC controller is connected to the existing thermostat 21 . The existing thermostat 21 is retained as a backup temperature control system.
[0067] The control processor 60 controls the HVAC equipment and the airflow to each room according to the temperature reported for each room and according to an independent temperature schedule for each room. The temperature schedules specify a heat-when-below-temperature and a cool-when-above-temperature for each minute of a 24-hour day. A different temperature schedule can be specified for each day for each room. These temperature schedules are specified by the occupants using a interface program operating on a standard PDA (personal data assistant) 80 . PDAs are available from several manufacturers such as Palm. The interface program provides graphical screens and popup menus that simplify the specification of the temperature schedules and the assignment of schedules to rooms for the days of the week and for other special dates. The PDA 80 includes a standard infrared communications interface called IrDA that is used to communicate with the control processor 60 . The IrDA link 81 is mounted in the most convenient air vent 18 behind its air grill 31 . The IrDA link 81 has an infrared transmitter and receiver mounted so that it can communicate with the PDA 80 using infrared signals though the air grill. The IrDA link 81 is connected to the control processor 60 by the link connection 82 that is pulled through the air duct with the air tube to that air vent. After changes are made to the temperature schedules, the PDA 80 is pointed toward the IrDA link 81 and the standard IrDA protocol is used to exchange information between the PDA 80 and the control processor 60 .
[0068] The IrDA link 81 also has an audio alarm and light that is controlled by the control processor 60 . The control processor can sound the alarm and flash the light to get the attention of the house occupants if the zone control system needs maintenance. The PDA 80 is used to communicate with the control processor 60 to determine specific maintenance needs.
[0069] The present invention can set the bladders so that all of the airflow goes to a single air vent, thereby conditioning the air in a single room. This could cause excessive air velocity and noise at the air vent and possibly damage the HVAC equipment. This is solved by connecting a bypass air duct 90 between the conditioned air plenum 15 and the return air plenum 11 . A bladder 91 is installed in the bypass 90 and its air tube is connected to an air valve 40 so that the control processor can enable or disable the bypass. The bypass provides a path for the excess airflow and storage for conditioned air. The control processor 60 is interfaced to a temperature sensor 61 located inside the conditioned air plenum 15 . The control processor monitors the conditioned air temperature to ensure that the temperature in the plenum 115 does not go above a preset temperature when heating or below a preset temperature when cooling, and ensures that the blower continues to run until all of the heating or cooling has been transferred to the rooms. This is important when bypass is used and only a portion of the heating or cooling capacity is needed, so the furnace or air conditioner is turned only for a short time. Some existing HVAC equipment has two or more heating or cooling speeds or capacities. When present, the control processor 60 controls the speed control and selects the speed based on the number of air vents open. This capability can eliminate the need for the bypass 90 .
[0070] A pressure sensor 62 is mounted inside the conditioned air plenum 15 and interfaced to the control processor 60 . The plenum pressure as a function of different bladder settings is used to deduce the airflow capacity of each air vent in the system and to predict the plenum pressure for any combination of air valve settings. The airflow to each room and the time spent heating or cooling each room is use to provide a relative measure of the energy used to condition each room. This information is reported to the house occupants via the PDA 80 .
[0071] This brief description of the components of the present invention installed in and existing residential HVAC system provides an understanding of how independent temperature schedules are applied to each room in the house, and the improvements provided by the present invention. The following discloses the details of each of the components and how the components work together to proved the claimed features.
Inflatable Bladders Used for Airflow Control Devices
[0072] FIG. 3 is a diagram showing the construction of the bladders 30 used airflow control devices. The bladders are constructed of flexible thin plastic or fabric coated with an airtight flexible sealer. The material is approved by UL or other listing agency for use in plenums. The bladders for controlling airflow in round air ducts are cylinders made by seaming together two circular shapes 301 and a rectangular shape 302 . Depending on the material, the airtight seams are heat sealed or glued. The material is only slightly elastic so the inflated size is determined by the dimensions of these shapes. An air tube connector 310 is sealed to the rectangular shape 302 . The air tube connector is molded from flexible plastic approved for use in plenums. FIG. 3A shows more detail of the air tube connector 310 , which has an air tube socket 312 sized so that it tightly grips the outside of the air tube 32 . The air tube connector provides the air path from the air tube to the inside of the bladder. The air tube connector is contoured to match the curvature of the round air duct and has a notch 311 to fit a mounting strap. This shape prevents conditioned air from leaking around the bladder when it is inflated. The inflated bladder 303 is about 110% the diameter of the air duct and its height is about 75% of the diameter. When inflated in the duct, the cylinder wall is pressed firmly against the inside of the air duct, effectively blocking all airflow. The deflated bladder 304 presents a small cross-section to airflow and restricts airflow by less than 10%. The standard round duct sizes connecting to air vents in residential installations are 4″, 6″, and 8″. Bypass 90 can be 6″, 8″, or 10″ in diameter. A total of only 4 different round duct bladder sizes are needed for residential installations.
[0073] The bladders for controlling airflow in rectangular ducts are also cylinders made by seaming together two circular shapes 321 and a rectangular shape 322 . The cylinder is oriented so that the axis of the cylinder is parallel to the widest dimension of the duct. The height of the cylinder is about 110% of the wider dimension of the duct. The cylinder diameter is at least 110% of the narrower dimension of the duct, but can be as much as 200%. When inflated, the bladder accepts only enough air to fill the air duct. FIG. 3B shows more detail of the air tube connector 330 , which is contoured for the flat surface of the rectangular duct and it has a notch 331 to fit a mounting strap and air tube socket 332 sized to fit the outside of the air tube 32 .
[0074] FIG. 4 shows several views of the method for mounting the bladder 30 in an air duct 17 at and air vent 18 covered by air grill 31 . Referring to FIG. 4E , the air tube 32 is inserted into the air tube socket 312 in the air tube connector 310 sealed to the bladder 30 shown with the top portion cut away. Mounting clamp 402 compresses the air tube socket around the air tube.
[0075] FIG. 4C is a plain view of the mounting strap, which is made form thin metal ( 18 gage) and is approximately 1″ by 12″. Hole 407 is used to secure the air tube to the mounting strap. One pair of holes 406 are used to secure the mounting clamp 402 to the mounting strap. Two of the holes 408 are used to secure the mounting strap to the inside of the air vent or air duct at the air vent.
[0076] FIG. 4D is a perspective drawing showing the mounting clamp 402 connecting to the mounting strap 401 . The mounting clamp straddles the air tube socket 312 (shown in FIG. 4E ) and two bladder clamp screws 405 pass through holes 406 in the mounting strap and screw into the mounting clamp. Several pairs of holes 406 (shown in FIG. 4C ) are provided so the bladder can be positioned for the most effective seal of the air duct. The screws 405 are self-tapping with flat heads that match counter-sinks pressed into the holes 406 in the mounting strap. Tightening the bladder clamp screws 405 cause the bladder clamp 402 to compress the air tube socket 312 firmly around the air tube 32 , securing the bladder to the mounting strap and ensuring an air tight seal between the air tube and the bladder. When tightened, the screw heads are flat with the bottom surface of the mounting strap, and the mounting strap fits in the notch 311 of the air tube connector 310 so the mounting strap is flat with the air tube connector.
[0077] FIG. 4F is a cross section view of the assembled bladder installed in an air duct 17 connecting to air vent 18 covered by air grill 31 . The air tube 32 is secured to the mounting strap 401 by the air tube clamp 403 (also shown in FIG. 4D ) using a screw 409 and nut through hole 407 (shown in FIG. 4C ). The air tube clamp transfers any tension on the air tube to the mounting strap and prevents strain on the connection between the air tube and the bladder. The mounting clamp 402 is connected to the mounting strap by two screws 405 and compresses the air tube socket 312 and secures the bladder 30 to the mounting strap. The mounting strap is secured to the inside of the air duct or air vent by two screws 404 through holes 408 (shown in FIG. 4C ). Some air vents are constructed with in integrated section of air duct several inched long, which fits inside the connecting air duct 17 . The inflated bladder can make contact with this extension of the air vent or it can make contact in the air duct when the extension is not part of the air vent.
[0078] FIG. 4A is an exploded perspective view of the assembled bladder 30 and mounting strap 401 fitting into the air duct 17 connected to air vent 18 . The inside of the air duct or air vent 410 where the bladder makes contact must be a smooth surface. If sharp sheet metal edges or screws are present, they are cut or smoothed and covered with duct mastic or duct tape to form a smooth surface and contour.
[0079] FIG. 4B is an exploded perspective view of an assembled bladder and air tube secured to amounting strap 401 for mounting inside a rectangular air duct 411 .
[0080] All installation and assembly work is done in the room where the air vent is located. The air grill is removed and an air tube 32 is pulled from the air vent to the plenum 15 . The air tube is secured to the mounting strap 401 and the proper size and shape bladder 30 is secured to the mounting strap. The inside surface 410 of the air vent or air duct is prepared by smoothing, cutting, or covering sharp edges and screws. In many cases, no preparation is required. This surface is chosen so it is close enough to the front of the air vent to provide convenient access for any surface preparation work. The mounting strap is inserted into the air vent and the mounting strap is bent and position so the inflated bladder meets the surface 410 . The mounting strap is then secured to the inside of the air vent by one or two sheet metal screws. The air grill is then reinstalled. After installation, the bladder is hidden by the air grill, and there are no visible signs of installation. The installation requires no other modification to the air duct, air vent, or air grill, and no other access to the air duct is required.
Servo Controlled Air Valves
[0081] FIG. 5 shows several views of one air valve of a plurality of servo controlled air valves 40 . The preferred embodiment has two valve blocks made of plastic using injection molding. Each valve block is approximately 1″×2″×7″ and contains valve cylinders for 12 valves.
[0082] FIG. 5A is a cross section view of one valve block 501 sectioned through one of the valve cylinders 502 . Each valve cylinder is 0.375″ in diameter and approximately 1.875″ deep. Each valve cylinder has three holes (˜0.188″) that connect the cylinder to the pressure cavity 503 , the valve header 504 (shown in cross section), and the vacuum cavity 505 . The valve header 504 connects the air tube 32 (shown in full view) to the valve cylinder and provides one side of the pressure and vacuum cavities in the valve block. The valve header is made of plastic using injection molding and is glued to the valve block to form airtight seals. The air tube 32 is press fit into the air tube hole 506 in the valve header. The inside of the air tube hole has a one-way compression edge 507 making it difficult to pull the air tube from the header after it has been inserted. The valve block is mounted on a side of the conditioned air plenum 15 so that the portion of valve header 504 connecting to the air tube is inside the plenum and the portion of the valve header sealing the pressure and vacuum cavities and the valve block 501 are outside the plenum.
[0083] FIG. 5C is a perspective view of the valve slide 510 and FIG. 5D is a top view of the same valve slide. The valve slide has groves for O-ring 511 and O-ring 512 . The valve slide has a valve lever 514 that protrudes above the valve plate 515 . The valve lever is used to move the valve slide inside the valve cylinder.
[0084] FIG. 5A and FIG. 5B represent the same air valve in two different positions. The valve slide 510 (shown in full view) fits snugly inside the valve cylinder 502 so that the O-rings seal the cavities formed by the cylinder wall and the valve slide. The slide valve has two resting positions, the pressure position 520 shown in FIG. 5B and the vacuum position 521 shown in FIG. 5A . The air pump 50 is turned on only when the valves are in one of these two positions. The air pump is off while the valves are moved. Referring to FIG. 5B , when the slide valve is in the pressure position 520 , O-ring 511 seals the vacuum cavity and the valve cylinder from the air tube. The cavity formed between O-ring 511 and O-ring 512 connects the pressure cavity to the air tube so pressurized air will flow through the air tube to inflate the bladder. O-ring 512 seals the valve cylinder from the outside air. Referring to FIG 5 A, when the slide valve is in the vacuum position 521 , the vacuum cavity is connected to the air tube and O-ring 511 seals the vacuum cavity from the pressure cavity. The bladder is deflated as air flows through the air tube towards the vacuum created by the air pump. O-ring 511 and O-ring 512 seals the pressure cavity from the air tube and outside air. The valve slide is moved to either the pressure position 520 or the vacuum position 521 by a servo that engages the valve lever 514 .
[0085] FIG. 5E shows an end view of a valve slide as positioned when in a valve cylinder. The valve lever 514 and valve plate 515 are constrained from rotating about the valve cylinder axis by a slot 516 in the valve constraint 513 . The valve constraint has a slot 516 for each valve slide. FIG. 5A also shows a side view of the valve plate 515 and the valve constraint 513 .
[0086] FIG. 6 shows several views of the two valve blocks 601 and 602 and air-feed tee 603 .
[0087] FIG. 6A is a cross-section view through the axis of the valve cylinders of valve block 601 and valve block 602 positioned so that the valve slides 510 (shown in full view) are interleaved. Interleaving minimizes the spacing between valve slides and aligns the valve levers 514 so the valve servo can move the valve slides in valve blocks 601 and 602 . Some of the valve slides are shown in the pressure position and the others are shown in the vacuum position. The valve constraint 513 has 24 slots 516 that engage the 24 valve slide plates to prevent rotation of the valve slide about the valve cylinder axis. The ends of the valve blocks 601 and 602 have passageways from the pressure and vacuum cavities to the air-feed tee 603 . O-rings 606 seal the connections between the air-feed tee and these passageways.
[0088] FIG. 6B is an end cross-section view through the section line shown in FIG. 6A of the passageways in the valve blocks 601 and 602 to the pressure cavities 503 and vacuum cavities 505 . The air-feed tee 603 is shown in full view. Four O-rings 606 seal the air-feed tee to the valve blocks. The air-feed tee has a vacuum connection 604 that connects to the vacuum air tube 52 and a pressure connection 605 that connects to the pressure air tube 51 . The valve levers 514 protrude beyond the surface of the valve blocks.
[0089] FIG. 6D is a top view of the air-feed tee 603 and O-rings 606 in isolation from the valve blocks. FIG. 6C is a cross-section view (through the section line shown in FIG. 6E ) of the-air-feed tee and the vacuum connection 604 . FIG. 6E is a front view of the air-feed tee in isolation. FIG. 6F is a cross-section view (through the section line shown in FIG. 6D ) of the air-feed tee through the center of the passageways connecting to the pressure and vacuum cavities.
[0090] FIG. 7 is a perspective drawing of the valve servo 700 . The servo carriage 701 is made of injection molded plastic. The servo carriage is supported by the position threaded rod 702 and the slide rod 703 . In the preferred embodiment, the position threaded rod is ⅜″ in diameter and has 16 threads per inch. The servo carriage has a position threaded bearing 704 that engages the position threaded rod. The position threaded bearing may be a threaded hole machined in the valve carriage plastic, or may be a threaded metal cylinder press fit into a hole in the servo carriage. The fit between the position threaded rod and the position threaded bearing is loose so there is minimum friction as the threaded rod rotates to move the servo carriage. The interface between the threaded rod and the threaded bearing provides support and constraint for the servo carriage for all directions except rotation about the axis of the threaded rod. Rotation constraint is provided by the smooth slide rod 703 that engages the carriage guide 705 . The fit between the slide rod and the carriage guide is loose so there is minimum friction as the carriage is moved by rotation of the position threaded rod.
[0091] The servo carriage has a bearing post 710 and a bearing plate 711 that support the two valve bearings 712 . The valve bearings are press fit into holes molded in the bearing post and bearing plate. The valve threaded rod 713 is a standard #8 sized screw with 32 threads per inch. The ends of the valve threaded rod are machined to fit the valve bearings so the rod can rotate with minimum friction and constrained so it can not move in any other way. The valve drive spur gear 714 is approximately 1 “in diameter and is fastened to the end of the valve threaded rod.
[0092] The valve motor 720 is mounted on the bearing plate 711 by two screws 721 (one screw 721 is hidden by spur gear 714 ) that pass through the bearing plate into the end of the motor. The valve motor spur gear 722 is approximately {fraction (3/16)}″ in diameter and is fastened to the shaft of the valve motor. The valve motor is positioned so that the valve motor spur gear engages the valve drive spur gear. The valve motor operates on 5 volts DC using approximately 0.3 A. It rotates CW or CCW depending on the direction of current flow. The control processor 60 has an interface circuit that enables it to drive the valve motor CW or CCW at full power. The control is binary on or off. The valve motor, valve motor spur gear, and valve drive spur gear are chosen so that the valve threaded rod rotates approximately 1000 RPM when the valve motor is driven.
[0093] The servo slider 730 has a slider threaded bearing 731 that engages the valve threaded rod 713 . The servo slider is supported by the valve threaded rod and is constrained by the threaded rod in all directions except rotation about the axis of the threaded rod. The servo slider passes through the slider slot 732 in the servo carriage. The slider slot constrains the servo slider so that as the valve threaded rod rotates, the servo slider can only move parallel to the axis of the slot and the axis of the valve threaded rod. The fit between the servo slider and the slider slot is loose to minimize friction as the slider moves.
[0094] The bearing post 710 and bearing plate 711 also support the valve PCB (printed circuit board) 740 . The valve PCB connects to a 6-conductor flat flexible cable 706 that connects to the interface circuit of the control processor 60 . Two wires from the valve motor connect to PCB 740 and to two conductors in the flexible cable. The valve PCB supports the A-photo-interrupter 741 and the B-photo-interrupter 742 . The photo-interrupters are positioned so that A-slider tab 743 and B-slider tab 744 on the servo slider 730 pass through the photo-interrupters as the servo slider is moved by the valve motor and valve threaded rod. The photo-interrupters generate binary digital signals that encode three positions of the of the servo slider. These digital signals are connected to the control processor through the flexible cable and are used by the control processor when driving the valve motor to position the servo slider.
[0095] FIG. 8 shows three views of the valve servo positioned over the valve blocks. FIG. 8A shows the valve blocks 601 and 602 in cross-section with the valve servo 700 positioned over one of the valve slides 510 in valve block 602 . The positions of the valve servo is established by the position threaded rod 702 , position threaded rod bearing 704 , slide rod 703 , and carriage guide 705 . The servo slider 730 is shown in the center position 800 . A-slider finger 810 and B-slider finger 811 have about {fraction (1/16)}″ clearance from any of the valve levers 514 in either the pressure position 520 or the vacuum position 521 . Both valve sliders are shown in the vacuum position. The A-photo-interrupter 741 and the B-photo-interrupter 742 are positioned so that neither the A-slider tab 743 nor the B-slider tab 744 interrupt the light path in the photo-interrupters when the servo slider is in the center position 800 . This is the only position where both photo-interrupters are uninterrupted.
[0096] FIG. 8B shows the servo slider in the B-position 801 corresponding to the pressure position 520 of the valve slide. In this position, the B-slider tab 744 interrupts the A-photo-interrupter 741 while the light path of the B-photo-interrupter is uninterrupted. When moving from the center position 800 to the B-position, both photo-interrupters are interrupted by the B-slider tab. To move the valve to the B-position, the control processor drives the valve motor until the light path of the B-photo-interrupter is uninterrupted. To return to the center position 800 , the valve motor direction is reversed and driven until both photo-interrupters are uninterrupted.
[0097] FIG. 8C shows the servo slider in the A-position 802 corresponding to the vacuum position 521 of the valve slide. In this position, the A-slider tab 743 interrupts the B-photo-interrupter 742 while the light path of the A-photo-interrupter 741 is uninterrupted. When moving from the center position 800 to the A-position, both photo-interrupters are interrupted by the A-slider tab. To move the valve to the A-position, the control processor drives the valve motor until the light path of the A-photo-interrupter is uninterrupted. To return to the center position 800 , the motor direction is reversed and driven until both photo-interrupters are uninterrupted.
[0098] When the control processor begins operation, the position of valve servo is unknown, and must be initialized. The valve servo is initialized first by testing the signals from the A- and B-photo-interrupters. If both are uninterrupted, then the valve servo is in the center position 800 and properly initialized. Any other combination of signals from the photo-interrupters represents one of two possible positions.
[0099] If both photo-interrupters are interrupted, then either the A-slider tab 743 or the B-slider tab 744 is interrupting the light paths. For this case, the servo slider is driven towards the B-position 801 until the B-photo-interrupter becomes uninterrupted. The servo slider either is in the B-position or is just right of the center position. After a pause for the valve motor to come to a stop, the servo slider is driven towards the B-position again. If the A-photo-interrupter becomes uninterrupted within a short time, the servo slider is in the center position, and the valve servo is initialized. If the A-photo-interrupter remains interrupted, then the servo slider is jammed in the B-position and must be driven towards the A-position until both photo-interrupters are uninterrupted.
[0100] If initially only the A-photo-interrupter is interrupted, then the servo slider either is in the B-position 801 or is slightly right of the center position. The servo slider is driven towards the B-position and if the A-photo-interrupter becomes uninterrupted within a short time, the servo slider is in the center position, and the valve servo is initialized. If the A-photo-interrupter remains interrupted, then the servo slider is jammed in the B-position and must be driven towards the A-position until both photo-interrupters are uninterrupted.
[0101] If initially only the B-photo-interrupter is interrupted, then the servo slider either is in the A-position 802 or is slightly left of the center position. The servo slider is driven towards the A-position and if the B-photo-interrupter becomes uninterrupted within a short time, the servo slider is in the center position, and the valve servo is initialized. If the B-photo-interrupter remains interrupted, then the servo slider is jammed in the A-position and must be driven towards the B-position until both photo-interrupters are uninterrupted.
[0102] FIG. 9 is a perspective drawing of the position servo 900 assembled with valve block 601 and valve block 602 . The position bearings 904 and 905 are press fit into holes in the motor bracket 902 and bearing bracket 903 . The position threaded rod 702 is machined to fit in the bearings and to constrain the threaded rod so that the only possible movement is rotation. The threaded rod is also machined so that the rotation cam 907 can be fastened to the end that protrudes beyond position bearing 905 and so that the position spur gear 906 can be fastened to the end that protrudes beyond position bearing 904 . The slide rod 703 is press fit into holes in the motor bracket and the bearing bracket. The bearing holes and the slide rod holes are positioned so that the position threaded rod and the slide rod are parallel to each other and to the valve blocks. The position threaded bearing 704 of the valve servo 700 engages the position threaded rod and the carriage guide 705 engages the slide rod 703 . The position motor 910 is attached with two screws 912 to the motor plate 911 , which is injection molded as part of the motor bracket 902 . The position motor is positioned so that the position worm gear 913 engages the position spur gear 906 .
[0103] Motor bracket 902 is attached to the valve block using screws. The motor bracket has molded spacers in line with the screw holes so that when attached, the motor bracket is perpendicular to the valve blocks and spaced so that the servo slider can be positioned over the air valve closest to the motor bracket. Likewise bearing bracket 903 is attached to the valve blocks using screws 921 . The bearing bracket has molded spacers in line with the screw holes so that when attached, the bearing bracket is perpendicular to the valve blocks and spaced so that the servo slider can be positioned over the air valve closest to the bearing bracket. The bearing bracket has a cutout at the bottom center so that the pressure air tube 51 and the vacuum air tube 52 can be attached to the air-feed tee 603 . The combination of the motor bracket, bearing bracket, and valve bank 601 and 602 connected together with screws form a rigid structure that is mounted as a single unit.
[0104] The position motor operates on 5 volts DC using approximately 0.5A. It rotates CW or CCW depending on the direction of current flow. The control processor 60 has an interface circuit that enables it to drive the position motor CW or CCW at full power. The control is binary on or off. The EOT (end of travel) photo-interrupter 930 is mounted on the bearing bracket 903 so that the carriage guide 705 interrupts the light path when the valve servo is positioned over the valve slide 510 closest to the bearing bracket. The binary digital signal from the EOT photo-interrupter is interfaced to control processor 60 . The rotation photo-interrupter 931 is mounted on the bearing bracket 903 and is positioned so that the rotation cam 907 interrupts the light path about 50% of the time as the position threaded rod rotates. For ½ of a rotation, the light path is interrupted and is uninterrupted for the other part of a rotation. The binary digital signal from the rotation photo-interrupter is interfaced to control processor.
[0105] When the control processor begins operation, the position of the valve servo carriage is unknown and must be initialized. If the EOT photo-interrupter is uninterrupted, the position servo is driven to move the valve servo carriage towards the bearing bracket until the EOT photo-interrupter's light path is interrupted by the carriage guide. The EOT photo-interrupter is positioned so that when the position motor stops, the servo slider 730 is positioned over the valve slide closest to the bearing bracket. If the EOT photo-interrupter is initially interrupted, the exact position of the valve servo carriage is not known. Therefore, the position servo is driven to move the valve servo away from the bearing bracket until the EOT photo-interrupter is uninterrupted. Then the position servo is driven to move the valve servo towards the bearing bracket until the EOT photo-interrupter is interrupted, just as if the EOT photo-interrupter was initially uninterrupted.
[0106] After the valve and position servos are initially positioned, the control processor can set the air valves by controlling the position and valve motors. Beginning with the air valve closest to the bearing bracket, the control processor moves the servo slider to either the A-position or the B-position to set the valve slider to the pressure position or the vacuum position. Then the servo slider is returned to the center position. Then the position servo is driven to move the valve servo so it is positioned over the second air valve. The position threaded rod has 16 threads per inch and the valve slides are spaced ¼″ center to center. Therefore, four revolutions of the threaded rod move the valve servo a distance equal to the distance between adjacent valve slides. The control processor monitors the rotation photo-interrupter 931 while the position threaded rod rotates, counting the number of transitions from interrupted to uninterrupted. After four such transitions, the position motor is stopped. Then the valve servo is drive to set the next valve, and after returning to the center position, the position motor drives the position threaded rod for four more revolutions. This cycle is repeated until all 24 valves are set. The preferred embodiment of the servo controlled valves requires less then one minute to set the positions of all 24 air valves.
[0107] After twenty-four air valves are set, the valve servo is positioned over the air valve closest to the motor bracket. The next time the valves are set, the position servo moves the valve servo toward the bearing bracket. The valve servo position is reinitialized by using the EOT photo-interrupter to set the position for the air valve closest to the bearing bracket. This ensures any errors in counting rotations are corrected every other cycle of setting air valves.
Air Pump and Relief Valves
[0108] FIG. 10 is a perspective the air pump enclosure 50 and its mounting system. The air pump 1020 has a vibrating armature that oscillates at the 60 Hz power line frequency. The preferred embodiment use pump model 6025 from Thomas Pumps, Sheboygan, Wis. It produces noise that could be objectionable in some installations.
[0109] The air pump is attached to the enclosure base 50 A by four shock absorbing mounting posts 1010 . The enclosure base is further isolated by using shock absorbing wall mounts 1011 . The enclosure base and enclosure cover 50 B are made of sound absorbing plastic to further isolate the noise. The enclosure cover has multiple small ventilation slots 1012 .
[0110] The pump PCB (printed circuit board) 1001 and the 5V DC power supply 1002 are fastened to the enclosure base 50 A. The pump PCB has a standard optically isolated triac circuit that uses a 5V binary signal from the control processor 60 to control the 110V AC power to the air pump. The pump PCB also has terminals to connect the 100V AC power cord 54 , the AC supply to 5V power supply 1003 , the 5V power from the supply 1004 , and the controlled AC supply to the air pump 1005 . The 3-conductor power and control cable