CN109059355B - Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner - Google Patents

Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner Download PDF

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Publication number
CN109059355B
CN109059355B CN201810809255.0A CN201810809255A CN109059355B CN 109059355 B CN109059355 B CN 109059355B CN 201810809255 A CN201810809255 A CN 201810809255A CN 109059355 B CN109059355 B CN 109059355B
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heat exchanger
conducting strip
frosting
capacitor
air conditioner
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CN109059355A (en
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贺杰
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Midea Group Co Ltd
GD Midea Air Conditioning Equipment Co Ltd
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Midea Group Co Ltd
GD Midea Air Conditioning Equipment Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/89—Arrangement or mounting of control or safety devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/006—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass for preventing frost
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/006—Preventing deposits of ice

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Other Air-Conditioning Systems (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention discloses a heat exchanger frosting detection device, a heat exchanger, an air conditioner and a defrosting control method thereof, wherein the heat exchanger frosting detection device comprises: the capacitor assembly comprises a fixed base, a first conducting plate and a second conducting plate, wherein the first conducting plate and the second conducting plate are arranged on the fixed base at intervals and form a capacitor; the first conducting strip and the second conducting strip are provided with sleeves, so that the first conducting strip and the second conducting strip are sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube; the first conducting strip and the second conducting strip are respectively connected with the capacitance detection module, and the capacitance detection module is configured to output a frosted voltage detection signal of the heat exchanger when the capacitance value of the capacitor is sensed to change. The invention realizes the accurate detection of the frosting degree of the heat exchanger, solves the problem of the reduction of the heating capacity of the air conditioner caused by the overlarge frosting thickness, and improves the working efficiency of the air conditioner.

Description

Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a heat exchanger frosting detection device, a heat exchanger, an air conditioner and a defrosting control method thereof.
Background
In a heat exchanger of a refrigeration apparatus such as an air conditioner, water is often precipitated at a low temperature, and the precipitated water is likely to adhere to the surface of the heat exchanger to form a frost layer. In the case of an air conditioner, as a frost layer is formed, the cooling or heating capacity of the air conditioner is reduced, which tends to lower the operating efficiency of the air conditioner.
Disclosure of Invention
The invention mainly aims to provide a heat exchanger frosting detection device, a heat exchanger, an air conditioner and a defrosting control method thereof, aiming at accurately detecting the frosting degree of the heat exchanger, solving the problem that the heating capacity of the air conditioner is reduced due to overlarge frosting thickness and improving the working efficiency of the air conditioner.
In order to achieve the above object, the present invention provides a heat exchanger frosting detection device, which includes:
the capacitor assembly comprises a fixed base, a first conducting strip and a second conducting strip, wherein the first conducting strip and the second conducting strip are arranged on the fixed base at intervals and form a capacitor;
the first conducting strip and the second conducting strip are provided with through holes so that the first conducting strip and the second conducting strip can be sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube;
The first conducting strip and the second conducting strip are respectively connected with the capacitance detection module, and the capacitance detection module is configured to output a voltage detection signal of frosting of the heat exchanger when the capacitance value of the capacitor is sensed to be changed.
Optionally, the through holes of the first conductive plate and the second conductive plate are respectively provided with an insulating ring.
Optionally, an insulating sleeve is disposed in the through holes of the first conducting strip and the second conducting strip.
Optionally, the heat exchanger frosting detection device further includes a first shielded cable and a second shielded cable, and the first shielded cable is connected to the first conductive sheet; the second shielded cable is connected with the second conductive sheet.
Optionally, the number of the capacitor assemblies is multiple, and the first conductive sheets and the second conductive sheets of the multiple capacitor assemblies are respectively connected with the capacitance detection module.
Optionally, the capacitance detection module includes a capacitance detection chip and a resonance unit, and the resonance unit is electrically connected to the frost detection sensor assembly to form a resonance circuit;
and the capacitance detection chip is connected with the resonance unit and used for detecting the resonance frequency of the resonance circuit, acquiring the capacitance value generated by the frosting detection sensor group according to the resonance frequency of the resonance circuit and generating a frosting detection signal.
The invention also provides a heat exchanger, which comprises the heat exchanger frosting detection device; the heat exchanger frosting detection device includes: the capacitor assembly comprises a fixed base, a first conducting strip and a second conducting strip, wherein the first conducting strip and the second conducting strip are arranged on the fixed base at intervals and form a capacitor; the first conducting strip and the second conducting strip are respectively provided with through holes which are sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube; the first conducting strip and the second conducting strip are respectively connected with the capacitance detection module, and the capacitance detection module is configured to output a voltage detection signal of frosting of the heat exchanger when the capacitance value of the capacitor is sensed to be changed.
Optionally, the heat exchanger is provided with a plurality of heat exchange portions from an input port to an output port of the heat exchange tube, the heat exchanger frosting detection device includes a plurality of capacitor assemblies, and each capacitor assembly is arranged in one-to-one correspondence with each heat exchange portion.
The invention also provides an air conditioner which comprises the heat exchanger.
The invention also provides a defrosting control method of the air conditioner, which is applied to the air conditioner, and the frosting detection method comprises the following steps:
Acquiring a frosting detection signal generated by the frosting detection device of the heat exchanger according to the capacitance value;
determining the frosting time T of the heat exchanger and the frosting thickness H of the heat exchanger according to the frosting detection signal;
and when the frosting time of the heat exchanger meets a first defrosting starting condition and the frosting thickness of the heat exchanger meets a second defrosting starting condition, controlling the air conditioner to defrost.
The frosting detection device of the heat exchanger is provided with a first conducting strip, a second conducting strip and a fixed base, and through holes are formed in the first conducting strip and the second conducting strip so that the first conducting strip and the second conducting strip can be arranged on a heat exchange tube or a fin of the heat exchanger to form a capacitor with frosting degree of the heat exchange tube of the heat exchanger. According to the formula C ∞ epsilonrIn the dielectric constant according to the thickness of frost condensed on the outer peripheral wall of the heat exchange tubeOr when the frosting degree is changed, the capacitance values of the first conducting strip, the second conducting strip and the capacitor are changed. And a capacitance detection module is arranged to generate a corresponding frosting detection signal according to the change of the capacitance value when the capacitor senses frosting on the heat exchanger. The invention realizes the accurate detection of the frosting degree of the heat exchanger, solves the problem of the reduction of the heating capacity of the air conditioner caused by the overlarge frosting thickness, and improves the working efficiency of the air conditioner.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic cross-sectional view of a frosting detection device of a heat exchanger according to an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view of another embodiment of the frosting detection apparatus of the heat exchanger of the present invention;
FIG. 3 is a schematic structural diagram of an embodiment of the frosting detection apparatus of the present invention when the capacitor module is arranged in a plurality;
FIG. 4 is a schematic circuit diagram of an embodiment of a frost detection device for a heat exchanger according to the present invention;
FIG. 5 is a graph of capacitance versus time C-T for the frost detection apparatus of the heat exchanger of the present invention;
FIG. 6 is a flowchart illustrating an embodiment of a defrosting control method for an air conditioner according to the present invention;
FIG. 7 is a schematic structural diagram of an embodiment of a heat exchanger frosting detection apparatus to which the defrosting control method of the air conditioner of the present invention is applied;
FIG. 8 is a schematic cross-sectional view of the frosting detection apparatus of FIG. 7 according to an embodiment;
FIG. 9 is another cross-sectional view of the frosting detection device of FIG. 7 according to an embodiment.
The reference numbers illustrate:
Figure BDA0001738113900000031
Figure BDA0001738113900000041
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides a heat exchanger frosting detection device, which is suitable for an air conditioner indoor unit, an outdoor heat exchanger, a refrigerator or other refrigeration equipment, and for convenience, an air conditioner is taken as an example.
The air conditioner can generally cool and heat, for example, in winter in the north, the air conditioner can work in the heating mode, and in the embodiment of the present invention, the air conditioner works in the heating mode, that is, the outdoor heat exchanger is in the heat absorption state when working, but not limited thereto.
When the air conditioner works in a heating mode, the outdoor temperature is below ten degrees or lower, if the outdoor heat exchanger needs to absorb heat at the moment, the temperature of the heat exchanger body can be reduced to be below 0 degree, moisture around the heat exchanger can be quickly condensed into frost, the heating effect of the air conditioner is certainly influenced, and similarly, when the indoor heat exchanger is in an indoor machine cooling mode, the indoor heat exchanger needs to absorb heat, the frosting phenomenon can occur on the indoor heat exchanger, and the cooling effect is influenced.
In order to solve the above problem, referring to fig. 1 to 5, in an embodiment of the present invention, the frost formation detecting apparatus for a heat exchanger includes:
the capacitor assembly 10 comprises a fixed base 11, a first conducting strip 12 and a second conducting strip 13, wherein the first conducting strip 12 and the second conducting strip 13 are arranged on the fixed base 11 at intervals and form a capacitor;
the first conducting strip 12 and the second conducting strip 13 are provided with through holes, so that the first conducting strip 12 and the second conducting strip 13 are sleeved on the heat exchange tube 100 and are in clearance fit with the heat exchange tube 100;
the capacitance detection module 20 is connected to the first conductive sheet 12 and the second conductive sheet 13, respectively, and the capacitance detection module 20 is configured to output a voltage detection signal indicating frosting of the heat exchanger when a capacitance value of the capacitor is sensed to be changed.
In this embodiment, the fixing base 11 can be implemented by selecting the fixing base 11 made of insulating materials such as plastic and ceramic. The fixing base 11 is provided with an insertion slot for the first conducting strip 12 and the second conducting strip 13 to be inserted, so that the fixing base 11 is integrally installed on the heat exchanger, and the assembly and disassembly efficiency of the fixing base 11 is improved. The fixed base 11 can be fixed on the heat exchanger by one or more combination of screw, bolt, riveting, clamping and inserting mode, and can be detachably connected with the heat exchanger. The fixed base 11 may also be fixedly mounted on the casing of the outdoor unit of the air conditioner, or fixedly mounted on other components in the outdoor unit, without limitation.
The first conductive sheet 12 and the second conductive sheet 13 are respectively provided with through holes through which the first conductive sheet 12 and the second conductive sheet 13 are disposed on the heat exchange pipe 100. The first conductive sheet 12 and the second conductive sheet 13 serve as two conductive electrodes to form two electrodes of a capacitor, frost attached to the outer peripheral wall of the heat exchange tube 100 of the heat exchanger, or air (when not frosted) can serve as a dielectric between the capacitors, that is, the first electrode, the heat exchange tube 100 and the frost or air (when not frosted) form a capacitor, and when water on the outer peripheral wall of the heat exchange tube 100 is condensed into frost, the dielectric can change along with the degree of frosting or the thickness of frosting. From electrostatics, the parallel plate capacitor has the following relationship:
Figure BDA0001738113900000061
Wherein epsilonrThe dielectric constant of an intermediate substance sandwiched between the first electrode and the second electrode, epsilon0In terms of vacuum absolute dielectric constant, A is the facing surface area of the first electrode and the second electrode, and d is the distance between the first electrode and the second electrode. As can be seen from equation (1), the capacitance of a capacitor is proportional to the dielectric constant of the dielectric, proportional to the area of the two plates, and inversely proportional to the distance between the two plates. Thus, after the first and second electrodes have been arranged, epsilon0A and d remain unchanged according to the aboveHas a linear formula C ∞ epsilonrAs the dielectric changes, the dielectric constant also changes according to the thickness of the frost layer 300 condensed on the outer peripheral wall of the heat exchange tube 100 or the degree of frost formation, so that the capacitance of the capacitor formed by the first conductive sheet 12 and the second conductive sheet 13 changes according to the change of the dielectric above the heat exchange tube 100, that is, according to the degree of frost formation of the outdoor heat exchanger.
It should be noted that, in order to improve the heat exchange efficiency of the heat exchanger, the heat exchange tubes 100 and the fins of the heat exchanger are generally made of a metal material, such as copper or a copper alloy, that is, the heat exchange tubes 100 are mostly conductive. In order to avoid the first conducting strip 12 and the second conducting strip 13 from being sleeved on the heat exchange tube 100, the first conducting strip 12 and the second conducting strip 13 are in contact with the heat exchange tube 100, and thus the first conducting strip 12 and the second conducting strip 13 are in short circuit, so that the first conducting strip 12 and the second conducting strip 13 cannot form two poles of a capacitor, and the problem of frosting change on the heat exchanger cannot be sensed, the first conducting strip 12 and the second conducting strip 13 are arranged in a gap with the heat exchange tube 100.
The capacitance detection module 20 generates a corresponding frosting detection signal according to the change of the capacitance value, so that the frosting degree of the outdoor heat exchanger of the outdoor unit can be accurately detected, the frosting detection signal can also be output to a main control board of the air conditioner, and when the frosting degree reaches a preset threshold value, defrosting protection is performed, so that the reduction of the heating capacity of the air conditioner caused by the overlarge frosting thickness is prevented, and the working efficiency of the heat exchanger of the air conditioner in the heating mode is improved.
The frosting detection device of the heat exchanger is provided with a first conducting strip 12, a second conducting strip 13 and a fixed base 11, and through holes are arranged on the first conducting strip 12 and the second conducting strip 13 so as to install the first conducting strip 12 and the second conducting strip 13 on a heat exchange tube 100 or fins of the heat exchanger, thereby forming a capacitor with frosting degree of the heat exchange tube 100 of the heat exchanger. According to the formula C ∞ epsilonrWhen the dielectric constant is changed according to the thickness of frost condensed on the outer peripheral wall of the heat exchange tube 100 or the degree of frost formation, the first conductive sheet 12 and the second conductive sheet are made to have a proportional relationshipThe capacitance of the capacitor, and of the capacitor plate 13, varies. And a capacitance detection module 20 is provided to generate a corresponding frosting detection signal according to the change of the capacitance value when the capacitor senses frosting on the heat exchanger. The invention realizes the accurate detection of the frosting degree of the heat exchanger, solves the problem of the reduction of the heating capacity of the air conditioner caused by the overlarge frosting thickness, and improves the working efficiency of the air conditioner.
Referring to fig. 1 to 5, in an alternative embodiment, the through holes of the first conductive sheet 12 and the second conductive sheet 13 are respectively provided with an insulating ring.
In this embodiment, the insulating rings are arranged in the through holes of the first conducting strip 12 and the second conducting strip 13, so as to further avoid the problem that the first conducting strip 12 and the second conducting strip 13 are sleeved on the heat exchange tube 100, and the first conducting strip 12 and the second conducting strip 13 are in contact with the heat exchange tube 100, so that the first conducting strip 12 and the second conducting strip 13 are short-circuited, and the first conducting strip 12 and the second conducting strip 13 cannot form two poles of a capacitor, and thus the frosting change on the heat exchanger cannot be induced; the design of the insulating ring also increases the structural strength of the first conducting strip 12 and the second conducting strip 13, so that the service life of the heat exchanger frosting detection device provided by the embodiment of the invention is longer. The insulating ring may be fitted with the heat exchange tube 100 of the heat exchanger to fixedly mount the first conductive sheet 12 and the second conductive sheet 13 on the tube, thereby improving the stability of the first conductive sheet 12 and the second conductive sheet 13. Or the insulating ring is arranged with a gap from the heat exchange tube 100 so that the air near the heat exchange tube can normally circulate and frost normally. And the first conductive sheet 12 and the second conductive sheet 13 are isolated from each other to form a frosting space, which is beneficial to improving the insulation between the first conductive sheet 12 and the second conductive sheet 13.
Referring to fig. 1 to 5, in an alternative embodiment, an insulating sleeve 14 is disposed in the through hole of the first conductive sheet 12 and the second conductive sheet 13.
In this embodiment, the insulating sleeve 14 is sleeved on the heat exchange tube 100, and then the first conducting strip 12 and the second conducting strip 13 are sleeved on the insulating sleeve 14, so that the first conducting strip 12 and the second conducting strip 13 are isolated from each other to form a frosting space, which is beneficial to improving the insulation between the first conducting strip 12 and the second conducting strip 13, so as to further avoid the problem that the first conducting strip 12 and the second conducting strip 13 cannot form two poles of a capacitor when the first conducting strip 12 and the second conducting strip 13 are sleeved on the heat exchange tube 100, the first conducting strip 12 and the second conducting strip 13 are in contact with the heat exchange tube 100, and thus the first conducting strip 12 and the second conducting strip 13 are short-circuited, so that the first conducting strip 12 and the second conducting strip 13 cannot form two poles of the capacitor. The insulating sleeve 14 may be adapted to the heat exchange tube 100 of the heat exchanger to fixedly mount the first conductive plate 12 and the second conductive plate 13 on the tube, so as to improve the stability of the first conductive plate 12 and the second conductive plate 13. Or the insulating sleeve 14 is disposed with a gap from the heat exchange pipe 100. In addition, a plurality of through holes can be further formed in the insulating sleeve to increase the contact area of the heat exchange tube and air, so that the air near the heat exchange tube can normally circulate and normally frosts.
Referring to fig. 1 to 5, in an alternative embodiment, the frost detection apparatus of the heat exchanger further includes a first shielded cable 30 and a second shielded cable 40, the first shielded cable 30 and the first conductive sheet 12, and the second shielded cable 40 is connected to the second conductive sheet 13 in a one-to-one manner.
In this embodiment, the parasitic capacitance between the capacitance detection module 20 and the ground can be eliminated by the shielding cable, and the influence of the external electromagnetic interference on the detection result is effectively reduced.
Referring to fig. 1 to 5, in an alternative embodiment, the number of the capacitor assemblies 10 is multiple, and the first conductive plates 12 and the second conductive plates 13 of multiple capacitor assemblies 10 are respectively connected to the capacitance detection module 20.
In this embodiment, the number of the capacitor assemblies 10 may be set to be plural, and the capacitor assemblies are correspondingly arranged on each heat exchanging portion of the heat exchanger from the input port to the output port of the coil. For example, under the low-temperature heating condition of the air conditioner, the liquid refrigerant 200 enters the input port of the heat exchange tube 100 to start heat exchange, evaporates and gasifies to absorb heat, and then circularly exchanges heat downwards along the copper tube, so that the temperature of the coil and the fins of the heat exchanger is probably lower than 0 ℃ from the input tube port to the output tube port. Therefore, the temperature of the input port is lower than the temperature of the rest of the heat exchanger, and the moisture on the periphery of the input pipe mouth of the heat exchange pipe 100 is condensed, so that the frost begins to form on the pipe at the input port of the heat exchange pipe 100. The temperature of the refrigerant 200 at the output port of the heat exchange tube 100 is higher after the heat exchange is completed, so that the water vapor at the periphery of the input port of the heat exchange tube 100 is not easy to condense, and the pipeline at the output port of the heat exchange tube 100 is not easy to frost. According to this feature, a capacitor assembly 10 may be disposed on the input pipe of the heat exchanger refrigerant 200 and forms a capacitor with the input pipe, so as to obtain the capacitance C1 when the outdoor heat exchanger starts frosting, and a capacitor assembly 10 may be disposed on the output pipe of the heat exchanger refrigerant 200 and forms a capacitor with the output pipe, so as to obtain the reference capacitance C0. Two capacitor assemblies 10 are fixed on the coil of the heat exchanger and form a capacitor with the coil, so that the variable capacitance values C2 and C3 in the frosting process of the heat exchanger can be respectively detected.
Referring to fig. 1 to 5, in an alternative embodiment, the capacitance detection module 20 includes a capacitance detection chip 21 and a resonant unit 22, and the resonant unit 22 is electrically connected to the capacitor assembly 10 to form a resonant tank;
the capacitance detection chip 21 is connected with the resonance unit 22, and the capacitance detection chip 21 is used for detecting the resonance frequency of the resonance circuit, acquiring the capacitance value generated by the capacitor assembly 10 according to the resonance frequency of the resonance circuit, and generating a frosting detection signal.
In this embodiment, the resonant unit 22 may be implemented by using an LC resonant circuit, and the capacitance detection chip 21 may be implemented by using an FDC2214 type capacitance detection IC. After the heat exchange tubes 100 of the first conductive sheet 12 and the second conductive sheet 13 form a capacitor, the capacitor and the resonant unit 22 together form a resonant circuit. When the capacitance value in the capacitor changes, the resonance frequency of the resonance circuit corresponding to the capacitor changes, and the capacitance detection chip 21 obtains the resonance frequency by driving the LC resonance tank, and detects the deviation of the resonance frequency of the LC resonance tank as the change of the capacitance value. Therefore, the resonance frequency of the resonance loop can be detected to obtain the capacitance value of the frosting capacitor so as to generate a frosting detection signal, and the change condition of the capacitance value is converted into a digital signal from an analog signal. The resonant frequency fsensor can be specifically calculated according to the following formula:
Figure BDA0001738113900000091
Where CH is a resonant frequency selection bit value in the capacitance detection chip 21, which may be set to 2 in the present embodiment. f. ofREFIs the reference frequency of the channel, fREFNot more than 35MHz, Count is the digital value converted by the capacitance-digital module in the capacitance detecting chip 21.
Further, the resonant unit 22 may specifically include a resonant capacitor C1 and a resonant inductor L1 connected in parallel, and two ends of the resonant capacitor C1 and the resonant inductor L1 connected in parallel are respectively connected to the two first signal input ends of the capacitance detection chip 21. The capacitor formed by the first electrode and the heat exchange pipe 100 may be disposed in series in the resonant unit 22, or may be disposed in parallel in the resonant unit 22. At this time, the first electrode may be grounded, and the heat exchange tube 100 is connected to one end of the resonant capacitor C1 and one end of the resonant inductor L1 which are connected in parallel; alternatively, the first electrode is connected to one end of the resonant capacitor C1 and the resonant inductor L1 connected in parallel, and the heat exchange tube 100 is grounded.
According to a capacitance calculation formula of the capacitance and the resonant frequency, the capacitance value Csense of the capacitor can be calculated as follows:
Figure BDA0001738113900000092
where Cx is the sum of the resonant capacitance C1 and the parasitic capacitance CPARASITI in the resonant tank.
The capacitance detection chip 21 can convert the detected Csensor of the capacitor into a 28-bit high-resolution digital result Count, so that a small change of the capacitance can be sensed to improve the detection accuracy of the capacitance.
It is understood that in the above embodiments, the smaller the value of Cx, the larger the capacitance value of the capacitor, and the higher the accuracy, in some embodiments, the capacitance value of the parallel capacitor C1 may be increased to increase the static baseline capacitance, so as to reduce the ratio CPARASITIC/C of the parasitic capacitance CPARASITIC to the baseline capacitance C1, so as to make the system more robust to noise interference, the resonant capacitance C1 may be implemented by selecting a ceramic NP0/COG patch capacitance, whose nominal capacitance value may be set to 39PF, and in a specific application process, the baseline capacitance, that is, the resonant capacitance, may be as close to the inductor coil as possible, so as to reduce the parasitic inductance of the circuit PCB trace. The capacitance detection chip 21 may specifically detect a voltage signal or a current signal at two ends of the resonant capacitor C1 or the resonant inductor L1, and obtain the resonant frequency of the resonant tank according to the frequency of the voltage signal or the current signal.
Referring to fig. 1 to 5, in an alternative embodiment, when the capacitor assembly 10 is provided in plurality, the number of the resonance units 22 corresponds to the number of the capacitor assembly 10, and each resonance unit 22 is connected to the capacitor formed by the corresponding first conductive plate 12 and the second conductive plate 13 to form a resonance circuit. In this embodiment, the number of the first conductive sheets 12 and the second conductive sheets 13 can be four, and the four first conductive sheets 12 and the four second conductive sheets 13 are respectively disposed at the input pipe orifice of the heat exchange pipe 100 and form a first capacitor with the heat exchange pipe 100 at the input pipe orifice, so as to sense the frosting change at the output of the input pipe orifice; or the coil pipe close to the input pipe orifice is provided with a second capacitor to detect the frosting change of the coil pipe in the heat exchange process; or the third capacitor is arranged at the output pipe orifice of the heat exchange pipe 100 to sense the frosting change of the output pipe orifice, or the fourth capacitor is formed on the coil pipe close to the output pipe orifice to sense the frosting change in the heat exchange process.
Each resonant unit 22 includes a resonant capacitor and a resonant inductor, and the circuit structure, the function, and the effects thereof can refer to the above embodiments, which are not described herein again.
In some embodiments, an RC filter circuit 23 is further disposed in series between the resonant tank and the capacitance detection chip 21, and the RC filter circuit 23 is used for filtering out noise in the resonant signal. The number of the RC filter circuits 23 may be one or multiple, and may be set correspondingly according to the number of the resonant circuits. In this embodiment, the number of the RC filter circuits 23 may be four, each RC filter circuit 23 includes a resistor and two capacitors, wherein the resistor is serially connected between the resonant circuit and the capacitance detection chip 21, one capacitor is serially connected between the capacitance detection chip 21 and the ground, and the other capacitor is serially connected between the parallel resonant circuit and the ground.
The invention also provides a heat exchanger, which comprises a heat exchange tube and the heat exchanger frosting self-checking device, wherein the first conducting strip and the second conducting strip are provided with through holes, so that the first conducting strip and the second conducting strip are sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube. . The detailed structure of the heat exchanger frosting detection device can refer to the above embodiment, and is not described again here; it can be understood that, because the heat exchanger frosting detection device is used in the heat exchanger of the present invention, the embodiment of the heat exchanger of the present invention includes all technical solutions of all embodiments of the heat exchanger frosting detection device, and the achieved technical effects are also completely the same, and are not described herein again.
Further, in the above embodiment, the heat exchanger is provided with a plurality of heat exchanging portions from an input port to an output port of the heat exchanging pipe, the frost detection device of the heat exchanger includes a plurality of capacitor assemblies, and each capacitor assembly and each heat exchanging portion are arranged in one-to-one correspondence.
In this embodiment, the heat exchange portion may be an input port of the heat exchange tube, or an output port of the heat exchange tube, or may be a coil formed by S-shaped bending. The capacitor assemblies can be arranged in a plurality, the number and the positions of the capacitor assemblies are arranged corresponding to those of the heat exchange part, for example, in one embodiment, when the heat exchange part is arranged as an input pipe orifice and an output port, the number of the capacitor assemblies is two, specifically, one capacitor assembly is arranged at the input port of the heat exchange pipe so as to sense the frosting change of the input pipe orifice; the other capacitor component is arranged at the output port of the heat exchange tube to sense the frosting change of the output port.
The invention also provides an air conditioner which comprises the heat exchanger, and the detailed structure and the effect of the heat exchanger can refer to the embodiment and are not repeated herein.
The invention also provides a defrosting control method of an air conditioner, which is applied to the air conditioner, and referring to fig. 6, the frosting detection method of the air conditioner comprises the following steps:
S10, acquiring a frosting detection signal generated by the frosting detection device of the heat exchanger according to the capacitance value;
in this embodiment, the frost formation detection apparatus includes: the capacitor assembly is provided with a fixed base, a first conducting strip, a second conducting strip and a frosting detection module, and is provided with a resonance unit and a capacitance detection chip, the first conducting strip and the second conducting strip form a capacitor to sense frosting change on the heat exchange tube, the capacitor and the resonance unit form a resonance loop, and the resonance frequency of the resonance loop is detected through the capacitance detection chip; the capacitance value of the capacitor is acquired according to the resonance frequency of the resonance circuit to generate a frosting detection signal. In some embodiments, the frost detecting apparatus further includes a first electrode, and the first electrode may form a capacitor with the heat exchange tube of the heat exchanger to sense a change in frost on the heat exchange tube.
S20, determining the frosting time T of the heat exchanger and the frosting thickness H of the heat exchanger according to the frosting detection signal;
it can be understood that under the low-temperature heating working condition of the air conditioner, the liquid refrigerant enters the input port of the heat exchange tube to start heat exchange, evaporates and gasifies to absorb heat, and then circularly exchanges heat downwards along the copper tube, so that the temperature of the coil and the fins of the heat exchanger is possibly lower than 0 ℃ from the input tube port to the output tube port. Therefore, the temperature of the input port is lower than the temperature of the other places of the heat exchanger, and the moisture on the periphery of the input pipe orifice of the heat exchange pipe is condensed, so that the frost begins to form on the pipe at the input port of the heat exchange pipe. The temperature of the refrigerant at the output port of the heat exchange tube is higher after the heat exchange is finished, so that the vapor at the periphery of the output port of the heat exchange tube is not easy to condense, and the pipeline at the input port of the heat exchange tube is not easy to frost. Referring to fig. 7 to 8, according to this characteristic, as shown in fig. 7, in this embodiment, a first conductive sheet and a second conductive sheet may be disposed on the refrigerant input nozzle of the heat exchanger, and form a capacitor (i.e., the first capacitor C10) with the input tube, so as to obtain a capacitance value C1 when the outdoor heat exchanger starts to frost, and a first conductive sheet and a second conductive sheet may be disposed on the refrigerant output nozzle of the heat exchanger, and form a capacitor (i.e., the second capacitor C20) with the output tube, so as to obtain a reference capacitance value C0. As shown in fig. 7 or fig. 8, fig. 7 and fig. 8 are two cross-sectional views of the first electrodes fixed on the heat exchanger coil, and the two first electrodes are fixed on the heat exchanger coil and form two capacitors (i.e. a third capacitor C30 and a fourth capacitor C40) with the coil, so that the variable capacitance values C2 and C3 in the frosting process of the heat exchanger can be detected.
Calculating a difference value delta C between a capacitance value C1 and a reference capacitance value C0 when the heat exchanger starts frosting according to the acquired capacitance value, namely delta C1 is equal to C1-C0, and obtaining time corresponding to the capacitance difference value through a capacitance change-time curve C-T graph, wherein the time is the frosting starting time T0 of the heat exchanger; calculating a capacitor detection formed by a first electrode of a heat exchanger coil close to an input pipe end of the heat exchanger and a third capacitor C30 formed by the coil in the frosting process of the heat exchanger to obtain a capacitance change value C2 in the frosting process of the heat exchanger, and a fourth capacitor C40 formed by the first electrode of the heat exchanger coil close to an output pipe end of the heat exchanger and the coil to obtain a difference value delta C2 of the capacitance change value C3 in the frosting process of the heat exchanger, namely delta C2 is C2-C3, and obtaining time corresponding to the capacitance difference value through a capacitance change-time curve C-T diagram, wherein the time is the continuous frosting time T1 of the heat exchanger; according to the frosting starting time T0 and the frosting lasting time T1, the frosting time T of the heat exchanger can be obtained, namely T is T1-T0.
The frosting thickness H can be calculated according to the following formula:
H＝ΔC2/K
the formula is a capacitance-frosting thickness empirical formula, H is the current frosting thickness of the outdoor heat exchanger, and K is a constant obtained through experiments. That is, the frost formation thickness H of the outdoor heat exchanger in the air conditioner is related to the difference Δ C2, i.e., H ∞ Δ C2.
And S30, when the frosting time of the heat exchanger meets a first frosting starting condition and the frosting thickness of the heat exchanger meets a second frosting starting condition, controlling the air conditioner to defrost.
The first defrosting starting condition can be set as that the frosting time of the heat exchanger is greater than a preset time threshold; the second frost start condition may be set such that a frost formation thickness H of the heat exchanger is greater than a first preset thickness H1.
Specifically, in the operation process of the air conditioner, the frosting thickness H of the outdoor heat exchanger can be obtained, and the frosting starting time T0 and the frosting continuing time T1 are obtained to obtain the frosting time T of the heat exchanger, that is, T is T1-T0, then it is determined whether the frosting thickness H of the outdoor heat exchanger is greater than a first preset thickness H1, and the frosting time T of the heat exchanger is greater than a preset time, and when the frosting thickness H of the outdoor heat exchanger is greater than the first preset thickness H1, and the frosting time T is greater than the preset time, the air conditioner is controlled to defrost. So set up, confirm the defrosting through combining outdoor heat exchanger frosting time and outdoor heat exchanger's frosting thickness together, can avoid frequently changing the energy consumption waste that the frost caused, improved the efficiency of changing the frost. Meanwhile, the problem that the heat exchange efficiency of the heat exchanger is low due to the fact that defrosting is carried out under the condition that the frosting of the heat exchanger is insufficient or the frosting is serious and the heat exchanger is not defrosted can be solved.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (8)

1. A heat exchanger frost detection device, characterized in that, heat exchanger frost detection device includes:
the capacitor assembly comprises a fixed base, a first conducting strip and a second conducting strip, wherein the first conducting strip and the second conducting strip are arranged on the fixed base at intervals and form a capacitor;
the first conducting strip and the second conducting strip are provided with through holes so that the first conducting strip and the second conducting strip can be sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube;
the first conducting strip and the second conducting strip are respectively connected with the capacitance detection module, and the capacitance detection module is configured to output a voltage detection signal of frosting of the heat exchanger when sensing the capacitance value change of the capacitor;
the through holes of the first conducting strip and the second conducting strip are respectively provided with an insulating ring, or insulating sleeves are arranged in the through holes of the first conducting strip and the second conducting strip;
The fixed base is plate-shaped and is used for being fixedly installed on a shell of the air conditioner outdoor unit or other parts, which are not heat exchange tubes, in the air conditioner outdoor unit.
2. The heat exchanger frost detection apparatus of claim 1, further comprising a first shielded cable and a second shielded cable, the first shielded cable being connected to the first conductive sheet; the second shielded cable is connected with the second conductive sheet.
3. The frost detection apparatus for a heat exchanger according to claim 1, wherein the number of the capacitor assemblies is plural, and the first conductive sheet and the second conductive sheet of the plural capacitor assemblies are respectively connected to the capacitance detection module.
4. The frost detection apparatus of any of claims 1 to 3, wherein the capacitance detection module comprises a capacitance detection chip and a resonance unit, and the resonance unit is electrically connected to the frost detection sensor assembly to form a resonance loop;
and the capacitance detection chip is connected with the resonance unit and used for detecting the resonance frequency of the resonance circuit, acquiring the capacitance value generated by the frosting detection sensor group according to the resonance frequency of the resonance circuit and generating a frosting detection signal.
5. A heat exchanger, characterized by comprising the heat exchanger frost detection device of any of claims 1-4, the heat exchanger comprises a heat exchange tube, the first conducting strip and the second conducting strip are provided with through holes, and the first conducting strip and the second conducting strip are sleeved on the heat exchange tube and are in clearance fit with the heat exchange tube.
6. The heat exchanger as claimed in claim 5, wherein the heat exchanger is provided with a plurality of heat exchanging portions from an input port to an output port of the heat exchanging pipe, and the frost detecting device for a heat exchanger comprises a plurality of capacitor elements, each of which is provided in one-to-one correspondence with each of the heat exchanging portions.
7. An air conditioner characterized by comprising the heat exchanger according to claim 5.
8. A frost formation detecting method of an air conditioner, applied to the air conditioner according to claim 7, wherein the frost formation detecting method comprises the steps of:
acquiring a frosting detection signal generated by the frosting detection device of the heat exchanger according to the capacitance value;
determining the frosting time T1 of the heat exchanger and the frosting thickness H of the heat exchanger according to the frosting detection signal;
and when the frosting time of the heat exchanger meets a first defrosting starting condition and the frosting thickness of the heat exchanger meets a second defrosting starting condition, controlling the air conditioner to defrost.
CN201810809255.0A 2018-07-20 2018-07-20 Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner Active CN109059355B (en)

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CN113324467B (en) * 2021-05-27 2023-03-31 贵州电网有限责任公司 Device and method for monitoring equivalent icing thickness of lead based on ice dielectric capacitance effect
CN114234538B (en) * 2021-12-20 2023-03-10 苏州热立方新能源有限公司 Frost layer recognition device, using method and probe automatic defrosting system

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