MODEL BASED AUTOMATIC CLIMATE CONTROL SYSTEM FOR AN IMPROVED THERMAL COMFORT

Abstract

A method of providing automatic climate control. A set point temperature input setting may be read. A cabin equivalent homogeneous temperature, computed real-time, may be compared to the set point temperature. A control value may be determined to equalize the cabin equivalent homogeneous temperature with the set point temperature.

Description

TECHNICAL FIELD

The field to which the disclosure generally relates includes climate control systems, and more particularly, includes automatic climate control in heating, ventilation and air conditioning systems.

BACKGROUND

Heated, ventilated and/or air conditioned spaces exist in a variety of environments and may be occupied by people, or used to contain other things. These spaces may be in mobile applications such as land, air and water vehicles, or in stationary applications such as buildings and containers. In certain applications the spaces may include a compartment or “cabin,” within which a person may be housed or transported. In other applications, “cabin” may refer generically to a contained space. A cabin may be provided with a ventilation system that supplies outside air to the cabin, a heating system which delivers air at an elevated temperature to the cabin, and an air conditioning system which delivers air at a reduced temperature to the cabin. The objective of these systems is to provide thermal comfort to the occupants of the cabin.

It is a challenge to determine how much heating, ventilating or cooling is required in order to provide an optimum thermal environment or comfort for all contained items such as occupants. Thermal sources may include the structure or its components, the occupants or contained items, outside air temperature and solar load, each of which may be variable. Within this environment, air stratification, heat storage in items such as the instrument panel of a vehicle, and discharge from nearby HVAC vents, may degrade the accuracy of the temperature measurement from an in-cabin temperature sensor upon which control may rely.

SUMMARY OF ILLUSTRATIVE VARIATIONS

A number of variations may involve a method of providing automatic climate control. A set point temperature input may be read. A cabin equivalent homogeneous temperature may be compared to the set point temperature. A control value may be determined to equalize the cabin equivalent homogeneous temperature with the set point temperature.

A number of additional variations may involve method of providing automatic climate control of a heating, ventilating and air conditioning system. A set point temperature input may be read. A cabin equivalent homogeneous temperature may be calculated. The cabin equivalent homogeneous temperature may be compared to the set point temperature. A control value may be generated to equalize the cabin equivalent homogeneous temperature with the set point temperature.

A number of other variations may involve a method of controlling an HVAC system. A set point temperature input may be read. A cabin equivalent homogeneous temperature may be obtained. The cabin equivalent homogeneous temperature may be compared to the set point temperature. A control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature may be generated. A control value may be determined based on the control error. The HVAC system may be adjusted based on the control value.

Other illustrative variations within the scope of the invention will become apparent from the detailed description provided herein. It should be understood that the detailed description and specific examples, while disclosing variations within the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Select examples of variations within the scope of the invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 illustrates a schematic diagram of automatic climate control system according to a number of variations.

FIG. 2 illustrates a method of automatic climate control according to a number of variations.

FIG. 3 illustrates a comfort curve graphed as comfort rating versus EHT according to a number of variations.

FIG. 4 illustrates a calibration curve graphed as EHT versus ambient temperature according to a number of variations.

DETAILED DESCRIPTION OF ILLUSTRATIVE VARIATIONS

The following description of the variations is merely illustrative in nature and is in no way intended to limit the scope of the invention, its application, or uses.

In a number of variations as illustrated in FIG. 1, a heating, ventilation, and air conditioning (HVAC), system 10 may be associated with a mobile or stationary application such as an air, land or water vehicle, a building or container, or another application, and may be an automatic climate control system. The system 10 may include an ambient air temperature sensor 12 for measuring the temperature of external ambient air (T_a). A cabin air temperature sensor 14 may be provided for measuring air temperature inside the cabin (T_c). A control device 16 may be provided, such as in the instrument panel of the vehicle, or at another location appropriate for the application, to provide a temperature setting desired by occupants such as the driver and front passenger of a vehicle, which may be the set point temperature (T_sp). The inputs T_a, T_c and T_sp may be provided to a controller 20.

Methods, algorithms, or parts thereof may be implemented in a computer program product of the controller 20 including instructions or calculations carried on a computer readable medium for use by one or more processors to implement one or more of the method steps or instructions. The computer program product may include one or more software programs comprised of program instructions in source code, object code, executable code or other formats; one or more firmware programs; or hardware description language (HDL) files; and any program related data. The data may include data structures, look-up tables, or data in any other suitable format. The program instructions may include program modules, routines, programs, objects, components, and/or the like. The computer program may be executed on one processor or on multiple processors in communication with one another.

In a number of variations, the program(s) may be embodied on computer readable media, which can include one or more storage devices, articles of manufacture, or the like. Illustrative computer readable media may include computer system memory, e.g. RAM (random access memory), ROM (read only memory); semiconductor memory, e.g. EPROM (erasable, programmable ROM), EEPROM (electrically erasable, programmable ROM), flash memory; magnetic or optical disks or tapes; and/or the like. The computer readable medium also may include computer to computer connections, for example, when data may be transferred or provided over a network or another communications connection (either wired, wireless, or a combination thereof). Any combination(s) of the above examples is also included within the scope of the computer-readable media. It is therefore to be understood that methods may be at least partially performed by any electronic articles and/or devices capable of executing instructions corresponding to one or more steps of the disclosed methods.

In a number of variations the controller 20 may produce signals that may be delivered to an HVAC blower 22 and may set the operational state and/or speed thereof. The controller 20 may produce signals to set the target discharge air temperature 24 such as at the discharge of the blower 22 and closed loop feedback may be provided to the controller 20. The controller 20 may produce signals that may be delivered to set the operational mode 26 of the HVAC system such as heating through a heater system, or cooling through an air conditioning system, or ventilating to provide outside air to the cabin.

In a number of variations as illustrated in FIG. 2, a method 30 may provide automatic climate control based on a cabin equivalent homogeneous temperature (EHT). The method 30 may provide for simplified calibration and shorten the time needed to perform calibration and may commence at step 32. It has been found that factors such as air stratification, heat storage in components such as the instrument panel, and vent discharge may impact the accuracy of the measured in-cabin temperature as compared to breath air temperature (i.e. air temperature adjacent to an occupant's face). Because of this, calibration of an automatic climate control system may be relatively challenging and time consuming.

In an enclosed space such as a vehicle cabin, occupant thermal comfort may be affected by environmental parameters that influence body heat loss such as surrounding air temperature, mean radiant temperature, air velocity, direct solar load, and humidity. One such parameter is breath air temperature which may be defined as the dry bulb temperature of the air near an occupant's face. Another parameter, mean radiant temperature can be defined as the uniform surface temperature of an imaginary enclosure in which an occupant would exchange the same amount of radiant heat as in the actual non-uniform space. The factors that affect thermal comfort are those that affect the body heat loss. The EHT is a recognized measure of the total heat loss from the human body that can be used to characterize highly non-uniform thermal environments. It is particularly useful in relation to a confined space such as a vehicle passenger compartment due to the complex interaction of radiation and convection heat fluxes. The advantage of EHT is that it expresses the effects of combined thermal influences in a single variable that is easy to interpret and explain in relation to occupant thermal comfort. EHT may be determined according to known methods and may be used as an input at step 32. One such method is described in published U.S. patent application Ser. No. 12/179,608 titled Automatic Climate Control for a Vehicle, and filed Jul. 25, 2008, which is assigned to the assignee of this application, and which is specifically incorporated herein by reference. For calibration, EHT may simply be selected from within a comfort range such as illustrated in FIG. 3 which depicts comfort rating on a 1-9 scale on the vertical axis 35 versus EHT in degrees Celsius on the horizontal axis 37. On an exemplary comfort scale, 1 may be classified as cold, 2 may be classified as very cool, 3 may be classified as cool, 4 may be classified as slightly cool, 5 may be classified as comfortable, 6 may be classified as slightly warm, 7 may be classified as warm, 8 may be classified as too warm, and 9 may be classified as hot. A first curve 39 represents cabin warming during cool ambient conditions, while a second curve 45 represents cabin cooling during warm ambient conditions. The discontinuity at the comfort rating of 5 is due to passengers wearing more clothing when ambient temperatures are cool and are therefore comfortable at a slightly cooler temperature. On the curves 39, 45 this may place “comfortable” in the area of 20-24 degrees Celsius depending on season and clothing level. As such, EHT may provide a single representative value to characterize a non-uniform thermal environment as a uniform thermal environment that relates to occupant thermal sensation.

The EHT may be calculated, or for purposes of calibration in the method 30, an EHT may be selected at step 34. EHT for neutral thermal sensation depends on the occupant metabolic rates and clothing level. In a number of variations a lookup table may be provided for the EHT set point based on these, and alternatively other, input parameters for an occupant thermal comfort. The EHT may be determined or selected for purposes of an example, as a value of 25 degrees Celsius, which may correspond to a comfort rating of approximately 6, being slightly warm. The method 30 may then proceed to step 36. Step 36 may receive an input from step 38 representative of the cabin temperature set point. With reference to FIG. 4, a calibration curve 44 for EHT set point is illustrated as EHT in degrees Celsius on the vertical axis 46 versus ambient temperature in degrees Celsius on the horizontal axis 48. Ambient temperature T_a may be described as the measured temperature in the external environment supplied by the temperature sensor 12 at step 40. The calibration curve may be a constant value of 22 degrees Celsius, regardless of ambient temperature. The value of 22 degrees may be provided from step 38 to step 36. Step 36 may subtract the set point of 22 degrees provided from step 38 from the EHT of 25 degrees provided from step 34 and may provide a control error or ΔEHT. In the example, the control error of 25−22=3 is provided from step 36 to step 42 and indicates that the HVAC system must adjust the cabin temperature down three degrees. The control error of 3 may be provided as a signal at 41. At step 42 the cabin EHT control may determine a control value Y_n=10·T_a+Y_pi(ΔT_c) that may be a combination of steady state (10·T_a), and transient (Y_pi(ΔT_c)), temperature based components. T_a may be measured ambient temperature, ΔT_c may be measured change in cabin temperature, and Y_pi may be a proportional-plus-integral control value. The control value Y_pi may be determined by K(T_sp−T_c)+K/T_i∫(T_sp−T_c)dτ, where K is a proportional gain constant and K/T_i is integral gain. In a number of variations the control value may be read from a lookup table by the controller 20 where a list of control values are listed by control error value. The determined control value Y_n may be provided from step 42 to step 43 where signals may be sent to the HVAC system to set a discharge air temperature 24, HVAC blower speed 22, and HVAC mode 26. Feedback provided by the sensors may be used to adjust the control value as the cabin temperature approaches the set point temperature.

The following description of variants is only illustrative of components, elements, acts, products and methods considered to be within the scope of the invention and are not in any way intended to limit such scope by what is specifically disclosed or not expressly set forth. The components, elements, acts, products and methods as described herein may be combined and rearranged other than as expressly described herein and still are considered to be within the scope of the invention.

Variation 1 may involve a method of providing automatic climate control. A set point temperature input setting may be read. A cabin equivalent homogeneous temperature may be compared to the set point temperature. A control value may be determined to equalize the cabin equivalent homogeneous temperature with the set point temperature.

Variation 2 may include the method according to variation 1 and may include calibration using a fixed set point temperature regardless of the ambient temperature.

Variation 3 may include the method according to variation 2 and may include selecting the fixed set point temperature based on a comfort rating.

Variation 4 may include the method according to variation 1 and may include providing a blower and a mode controller, and controlling the blower and the mode controller using the control value.

Variation 5 may include the method according to variation 1 and may include determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component.

Variation 6 may include the method according to variation 1 and may include sensing an ambient temperature, sensing a cabin temperature and using the ambient temperature and the cabin temperature to generate the control value.

Variation 7 may include the method according to variation 1 and may include setting a blower speed, setting a discharge temperature, and setting an HVAC mode, all based on the cabin equivalent homogeneous temperature and the set point temperature.

Variation 8 may include the method according to variation 1 and may include determining a control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature.

Variation 9 may involve method of providing automatic climate control of a heating, ventilating and air conditioning system. A set point temperature input may be read. A cabin equivalent homogeneous temperature may be calculated. The cabin equivalent homogeneous temperature may be compared to the set point temperature. A control value may be generated to equalize the cabin equivalent homogeneous temperature with the set point temperature.

Variation 10 may include the method according to variation 9 and may include calibrating using a fixed set point temperature regardless of the ambient temperature.

Variation 11 may include the method according to variation 10 wherein the fixed set point temperature may be 22 degrees Celsius.

Variation 12 may include the method according to variation 9 and may include providing a blower and a mode controller, and controlling the blower and the mode controller using the control value.

Variation 13 may include the method according to variation 9 and may include determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component.

Variation 14 may include the method according to variation 9 and may include sensing an ambient temperature, sensing a cabin temperature and using the ambient temperature and the cabin temperature to generate the control value.

Variation 15 may include the method according to variation 9 and may include setting a blower speed, setting a discharge temperature, and setting an HVAC mode all based on the cabin equivalent homogeneous temperature and the set point temperature.

Variation 16 may include the method according to variation 9 and may include determining a control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature.

Variation 17 may involve a method of controlling an HVAC system. A set point temperature input may be read. A cabin equivalent homogeneous temperature may be obtained. The cabin equivalent homogeneous temperature may be compared to the set point temperature. A control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature may be generated. A control value may be determined based on the control error. The HVAC system may be adjusted based on the control value.

Variation 18 may include the method according to variation 17 and may include determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component to obtain the control value.

Variation 19 may include the method according to variation 17 and may include sensing an ambient temperature, sensing a cabin temperature and using the ambient temperature and the cabin temperature to determine both the steady state control value component and the transient control value component.

Variation 20 may include the method according to variation 17 and may include setting a blower speed, setting a discharge temperature, and setting an HVAC mode all based on the cabin equivalent homogeneous temperature and the set point temperature.

The above description of select variations within the scope of the invention is merely illustrative in nature and, thus, variations or variants thereof are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A method of providing automatic climate control comprising reading a set point temperature input, comparing a cabin equivalent homogeneous temperature to the set point temperature, and generating a control value to equalize the cabin equivalent homogeneous temperature with the set point temperature.

2. The method according to claim 1 further comprising calibrating using a fixed set point temperature regardless of the ambient temperature.

3. The method according to claim 2 further comprising selecting the fixed set point temperature based on a comfort rating.

4. The method according to claim 1 further comprising providing a blower and a mode controller, and controlling the blower and the mode controller using the control value.

5. The method according to claim 1 further comprising determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component.

6. The method according to claim 1 further comprising sensing an ambient temperature, sensing a cabin temperature and using the ambient temperature and the cabin temperature to generate the control value.

7. The method according to claim 1 further comprising setting a blower speed, setting a discharge temperature, and setting an HVAC mode all based on the cabin equivalent homogeneous temperature and the set point temperature.

8. The method according to claim 1 further comprising determining a control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature.

9. A method of providing automatic climate control of a heating, ventilating and air conditioning system comprising reading a set point temperature input, calculating a cabin equivalent homogeneous temperature, comparing the cabin equivalent homogeneous temperature to the set point temperature, and generating a control value to equalize the cabin equivalent homogeneous temperature with the set point temperature.

10. The method according to claim 9 further comprising calibrating using a fixed set point temperature regardless of the ambient temperature.

11. The method according to claim 10 wherein the fixed set point temperature is 22 degrees Celsius.

12. The method according to claim 9 further comprising providing a blower and a mode controller, and controlling the blower and the mode controller using the control value.

13. The method according to claim 9 further comprising determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component.

14. The method according to claim 9 further comprising sensing an ambient temperature, sensing a cabin temperature, and using the ambient temperature and the cabin temperature to generate the control value.

15. The method according to claim 9 further comprising setting a blower speed, setting a discharge temperature, and setting an HVAC mode all based on the cabin equivalent homogeneous temperature and the set point temperature.

16. The method according to claim 9 further comprising determining a control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature.

17. A method of controlling an HVAC system comprising reading a set point temperature input, obtaining a cabin equivalent homogeneous temperature, comparing the cabin equivalent homogeneous temperature to the set point temperature, generating a control error based on a difference between the cabin equivalent homogeneous temperature and the set point temperature, determining a control value based on the control error, and adjusting the HVAC system based on the control value.

18. The method according to claim 17 further comprising determining a steady state control value component, determining a transient control value component and combining the steady state control value component and the transient control value component to obtain the control value.

19. The method according to claim 9 further comprising sensing an ambient temperature, sensing a cabin temperature and using the ambient temperature and the cabin temperature to determine both the steady state control value component and the transient control value component.

20. The method according to claim 17 further comprising setting a blower speed, setting a discharge temperature, and setting an HVAC mode all based on the cabin equivalent homogeneous temperature and the set point temperature.