CN109059356B - 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 PDFInfo
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- CN109059356B CN109059356B CN201810809313.XA CN201810809313A CN109059356B CN 109059356 B CN109059356 B CN 109059356B CN 201810809313 A CN201810809313 A CN 201810809313A CN 109059356 B CN109059356 B CN 109059356B
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- heat exchanger
- frosting
- heat exchange
- exchange tube
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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
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- 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
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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
- 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
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- 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
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 capacitance detection module is provided with a first signal end and a second signal end which is used for being connected with a heat exchange tube of the heat exchanger; the first electrode is connected with the first signal end and used for being arranged on a heat exchange tube or a fin of the heat exchanger so as to enable the first electrode and the heat exchange tube of the heat exchanger to form a capacitor; the capacitance detection module is configured to output a frosting detection signal of frosting 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 outdoor heat exchanger of the outdoor unit, 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
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 capacitance detection module is provided with a first signal end and a second signal end which is used for being connected with a heat exchange tube of the heat exchanger;
the first electrode is connected with the first signal end and used for being arranged on a heat exchange tube or a fin of a heat exchanger so as to enable the first electrode and the heat exchange tube of the heat exchanger to form a capacitor;
the capacitance detection module is configured to output a frosting detection signal of frosting of the heat exchanger when the capacitance value of the capacitor is sensed to be changed.
Optionally, the first electrode is an annular metal sleeve fitted with the heat exchange tube sleeve.
Optionally, the heat exchanger frosting detection device further includes a first fixed base, the annular metal sleeve is connected to the first fixed base, and the annular metal sleeve is mounted on the heat exchanger through the first fixed base.
Optionally, the first fixing base includes two oppositely disposed clamping arms, and a clamping groove adapted to the annular metal sleeve is formed between the two clamping arms.
Optionally, the first electrode is a metal plate.
Optionally, the heat exchanger frosting detection device further includes a second fixed base, the metal pole plate is connected to the second fixed base, and the metal pole plate is mounted on the fin of the heat exchanger through the second fixed base.
Optionally, the second fixing base includes a bottom plate and a connecting portion for connecting with a fin of the heat exchanger, the connecting portion is disposed on one side of the bottom plate, and the metal plate is embedded in the bottom plate.
Optionally, the capacitance detection module includes a capacitance detection chip and a resonance unit, the resonance unit is electrically connected to the first electrode, and a heat exchange tube of the heat exchanger is grounded to form a resonance circuit; two first signal input ends of the capacitance detection chip are connected with the resonance unit; wherein the content of the first and second substances,
the capacitance detection chip is used for detecting the resonant frequency of the resonant circuit and acquiring the capacitance value generated by the frosting detection sensor group according to the resonant frequency of the resonant circuit so as to generate a frosting detection signal.
The invention also provides a heat exchanger, which comprises a heat exchange tube, fins and the heat exchanger frosting detection device; the heat exchanger frosting detection device includes: the capacitance detection module is provided with a first signal end and a second signal end which is used for being connected with the heat exchange tube; the first electrode is connected with the first signal end and used for being mounted on the heat exchange tube or the fins so as to form a capacitor with the heat exchange tube; the capacitance detection module is configured to output a frosting detection signal of frosting of the heat exchanger when the capacitance value of the capacitor is sensed to be changed.
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 invention provides a frost detection device of a heat exchanger, which is provided with a first electrode, wherein the first electrode is arranged on a heat exchange tube or a fin of the heat exchanger to form a capacitor with the heat exchange tube of the heat exchanger, and the capacitor is in accordance with the formula C ^ epsilonrThe dielectric constant varies depending on the thickness of frost condensed on the outer peripheral wall of the heat exchange tube or the degree of frost formation, so that the capacitance value of the capacitor formed by the first electrode and the heat exchange tube of the heat exchanger varies. 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 accurate detection of frosting degree of the outdoor heat exchanger of the outdoor unit, and solves the problem of excessive frosting thicknessThe problem of the reduction of the heating capacity of the air conditioner 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 another embodiment of the frost detection apparatus for a heat exchanger according to the present invention;
FIG. 4 is a schematic cross-sectional view of another embodiment of the frosting detection apparatus of the heat exchanger of the present invention;
FIG. 5 is a schematic cross-sectional view of a frosting detection device of a heat exchanger according to another embodiment of the present invention;
FIG. 6 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. 7 is a schematic circuit diagram of a frosting detection device of the heat exchanger according to an embodiment of the present invention;
FIG. 8 is a graph of capacitance versus time C-T for the frost detection apparatus of the heat exchanger of the present invention;
fig. 9 is a flowchart illustrating an embodiment of a frost formation detection method for an air conditioner according to the present invention.
The reference numbers illustrate:
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 indoor or outdoor heat exchangers of air conditioners, refrigeration equipment such as refrigerators and the like, and the air conditioners are taken as examples for convenience in description below.
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 8, in an embodiment of the present invention, the frost formation detecting apparatus for a heat exchanger includes:
a capacitance detection module 10 having a first signal terminal and a second signal terminal for connecting with a heat exchange tube 100 of the heat exchanger;
the first electrode 20, the first electrode 20 is connected with the first signal end, and the first electrode 20 is used for being mounted on a heat exchange tube 100 or a fin 400 of a heat exchanger, so that the first electrode 20 and the heat exchange tube 100 of the heat exchanger form a capacitor;
the capacitance detection module 10 is configured to output a voltage detection signal of heat exchanger frosting when sensing a capacitance value change of the capacitor.
The first signal terminal may be a ground terminal and the second signal terminal is a signal input terminal, or the first signal terminal is a signal input terminal and the second signal terminal is a ground terminal. In this embodiment, the second signal terminal can be selected as a ground terminal, i.e., the heat exchange tube 100 is grounded, so as to improve the safety of the air conditioner.
In this embodiment, the heat exchanger is used as the second electrode, and forms two electrodes of the capacitor with the first electrode 20, and the frost or air (when not frosted) between the first electrode 20 and the heat exchange tube 100 can be used as a dielectric medium between the capacitors, that is, the first electrode 20, the heat exchange tube 100, and the frost or air (when not frosted) form a capacitor. When moisture on the outer peripheral wall of the heat exchange tube 100 condenses into frost, the dielectric substance varies depending on the degree of frost formation or the thickness of the frost formation. From electrostatics, the parallel plate capacitor has the following relationship:
wherein epsilonrIs the dielectric constant, epsilon, of an intermediate substance sandwiched between the first electrode 20 and the second electrode0In terms of the vacuum absolute dielectric constant, a is the facing surface area of the first electrode 20 and the second electrode, and d is the distance between the first electrode 20 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 electrode 20 and the second electrode have been arranged, ε0A and d remain unchanged, and are equal to epsilon according to the relational expression CrSince the dielectric constant also varies according to the thickness of frost condensed on the outer peripheral wall of the heat exchange tube 100 or the degree of frost formation as the dielectric varies, the capacitance of the capacitor formed by the first electrode 20 and the heat exchange tube 100 of the heat exchanger varies according to the dielectric variation of the heat exchange tube 100, that is, according to the degree of frost formation of the outdoor heat exchanger.
The capacitance detection module 10 generates a corresponding frosting detection signal according to the capacitance value change, 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 heating capacity of the air conditioner is prevented from being reduced due to the fact that the frosting thickness is too large, and the working efficiency of the heat exchanger of the air conditioner in the heating mode is improved.
The frost formation detecting apparatus for a heat exchanger according to the present invention is provided with a first electrode 20, and the first electrode 20 is mounted on a heat exchange tube 100 or a fin 400 of the heat exchanger so as to constitute a capacitor with the heat exchange tube 100 of the heat exchanger, and varies from C to εrIn the dielectric constant according to condensation on the outer peripheral wall of the heat exchange tube 100The thickness or degree of frost thereon is changed, so that the capacitance of the capacitor formed by the first electrode 20 and the heat exchange tube 100 of the heat exchanger is changed. And a capacitance detection module 10 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 outdoor heat exchanger of the outdoor unit, 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 8, in an alternative embodiment, the first electrode 20 is an annular metal sleeve fitted with the heat exchange tube 100.
In this embodiment, the annular metal sleeve is disposed on the heat exchange tube 100 in a spaced manner, so that the annular metal sleeve and the heat exchange tube 100 are isolated from each other to form a frosting space, and when the frost layer 300 is condensed on the heat exchange tube 100, the capacitor formed by the annular metal sleeve and the heat exchange tube 100 can sense the frost layer 300 on the heat exchange tube 100. The annular metal sheath may be implemented by a copper mesh to increase a contact area of the heat exchange pipe 100 with air and to allow the air near the heat exchange pipe to normally circulate, thereby normally frosting. The annular metal sleeve is arranged on the heat exchange tube 100 in a spaced manner and forms a capacitor with the heat exchange tube 100, so that the area of a polar plate of the capacitor is increased, the electric polarity of the capacitor can be effectively increased, and the detection sensitivity of the heat exchanger frosting detection device to a frost layer is improved. In this embodiment, the heat exchange tube 100 is used as an electrode of the capacitor, and the annular metal sleeve is arranged to be sleeved on the heat exchange tube 100 to form two electrodes of the capacitor, i.e., the capacitor is formed by using the structure of the heat exchanger itself, so that the structure is simple, the installation is convenient, and the installation space of the heat exchanger frosting detection device can be effectively saved. The heat exchanger frosting detection device is easy to realize, low in cost and widely applicable to frosting detection of heat exchangers in refrigeration equipment such as indoor or outdoor heat exchangers of air conditioners, refrigerators and the like.
Further, the heat exchanger frosting detection device further comprises a first fixed base 30, the annular metal sleeve is connected with the first fixed base 30, and the annular metal sleeve is installed on the heat exchanger through the first fixed base 30.
In this embodiment, the first fixing base 30 can be fixed on the heat exchanger by one or more combination of screws, bolts, riveting, clamping and plugging, and can be detachably connected with the heat exchanger. The first fixing base 30 can be made of plastic, ceramic, or other insulating materials. The first fixing base 30 may also be used to fix the annular metal sleeve to the outer casing of the outdoor unit of the air conditioner, or to fix the annular metal sleeve to other components of the outdoor unit, which is not limited herein.
Further, the first fixing base 30 includes two opposite clamping arms, and a clamping groove adapted to the annular metal sleeve is formed between the two clamping arms.
In this embodiment, two centre gripping arms are with annular metal covering centre gripping in the centre gripping inslot to make annular metal covering be fixed in on the heat exchanger, two centre gripping arms can also be fixed centre gripping arm and activity centre gripping arm respectively, can pass through clamping spring fixed connection between fixed centre gripping arm and the activity centre gripping arm.
Further, the first fixing base 30 may further include a fixing portion for detachably connecting to an object to be mounted, and the two holding arms are disposed on the fixing portion. The fixing part can be formed by extending a fixing clamping arm outwards, or the fixing part and the fixing clamping arm are detachably connected in a screw, bolt, riveting, clamping and inserting mode.
Referring to fig. 1 to 8, in an alternative embodiment, the first electrode 20 is a metal plate.
In this embodiment, the metal polar plate sets up on the fin 400 of heat exchanger, and mutual isolation forms the space of frosting between metal polar plate and the heat exchange tube 100, and it can be understood that, the coil pipe that the heat exchange tube 100 can form through the S-shaped bending, and the metal polar plate sets up with the coil pipe relatively to coil pipe and the just positive periphery wall of metal polar plate all can set up to the electrode of condenser, thereby increase the detection area of heat exchanger, improve the detectivity of heat exchanger frosting.
Further, the heat exchanger frosting detection device further comprises a second fixing base 40, the metal pole plate is connected with the second fixing base 40, and the metal pole plate is installed on the fin 400 of the heat exchanger through the second fixing base 40.
In this embodiment, the second fixing base 40 can be implemented by a fixing base made of an insulating material such as plastic, ceramic, etc. The metal plates are fixedly mounted on the fins 400 through an insulating fixing base, thereby forming a capacitor with the heat exchange pipe 100 to which the fins 400 are mounted. It is understood that the second fixing base 40 can also fix the annular metal sleeve on the outer casing of the outdoor unit of the air conditioner, or other components in the outdoor unit, which is not limited herein.
Further, the second fixing base 40 includes a bottom plate 41 and a connecting portion 42 for connecting with the fin 400 of the heat exchanger, the connecting portion 42 is disposed on one side of the bottom plate 41, and the metal plate is embedded in the bottom plate 41.
In this embodiment, the connection portion 42 is provided with a slot for inserting the fin 400 when the fixing base is fixed on the fin 400, so that the base plate 41 is fixedly mounted on the fin 400 of the heat exchanger. When the second fixing base 40 is manufactured, the metal plate may be placed in a mold, the insulating plastic package material is changed into a flowing state by heating and then injected into the mold, and after curing, the bottom plate 41 is formed and the metal plate is embedded in the bottom plate 41 and integrally disposed with the bottom plate 41. The bottom plate 41 can be hollowed out, so that the metal plate and the heat exchange tube 100 respectively form two electrodes of the capacitor, thereby increasing the area of the electrode plate of the metal plate, further improving the detection sensitivity of the heat exchanger frosting detection device to the frost layer, and enabling the air near the heat exchange tube to normally circulate and frost normally. Connecting portion 42 can set up through mould and bottom plate 41 integrated into one piece, also can bond to bottom plate 41 through modes such as glue, double faced adhesive tape on, set up with bottom plate 41 is integrative, be favorable to with the fixed baseplate monolithic erection to the fin 400 of heat exchanger on, improve fixed baseplate's dismouting efficiency.
Referring to fig. 1 to 8, in an alternative embodiment, the number of the first electrodes 20 is multiple, the number of the first signal terminals of the capacitance detection module 10 is multiple, and the multiple first electrodes 20 are connected to the multiple first signal terminals of the capacitance detection module 10 in a one-to-one manner.
In this embodiment, the number of the first electrodes 20 may be provided in plural, and the first electrodes are correspondingly provided 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 exchange heat, 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 400 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, the first electrode 20 is disposed on the inlet pipe of the heat exchanger coolant 200 and forms a capacitor with the inlet pipe, so as to obtain the capacitance C1 when the outdoor heat exchanger starts frosting, and the first electrode 20 is disposed on the outlet pipe of the heat exchanger coolant 200 and forms a capacitor with the outlet pipe, so as to obtain the reference capacitance C0. The first electrode 20 is fixed to the heat exchanger coil or fin 400 and forms a capacitor with the coil, so that the capacitance C2 that changes during the frosting process of the heat exchanger can be detected.
Referring to fig. 1 to 8, in an alternative embodiment, the capacitance detection module 10 includes a capacitance detection chip 11 and a resonant unit 12,
the capacitance detection module 10 comprises a capacitance detection chip 11 and a resonance unit 12, the resonance unit 12 is electrically connected with the first electrode 20, and a heat exchange tube 100 of the heat exchanger is grounded to form a resonance loop; two first signal input ends of the capacitance detection chip 11 are connected with the resonance unit 12; wherein the content of the first and second substances,
the capacitance detection chip 11 is configured to detect a resonant frequency of the resonant tank, and acquire a capacitance value generated by the frosting detection sensor group according to the resonant frequency of the resonant tank to generate a frosting detection signal.
In this embodiment, the resonant unit 12 may be implemented by an LC resonant circuit, and the capacitance detection chip 11 may be implemented by an FDC2214 type capacitance detection IC. After the first electrode 20 and the heat exchange tube 100 of the heat exchanger form a capacitor, the capacitor and the resonance unit 12 together form a resonance 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 11 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:
where CH is a resonant frequency selection bit value in the capacitance detection chip 11, which may be set to 2 in this embodiment. f. ofREFIs the reference frequency of the channel, fREFAnd the Count is not more than 35MHz, and is the digital value converted by the capacitor-digital module in the capacitor detection chip 11.
Further, the resonant unit 12 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 11. The capacitor formed by the first electrode 20 and the heat exchange pipe 100 may be disposed in series in the resonance unit 12, or may be disposed in parallel in the resonance unit 12. At this time, the first electrode 20 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 20 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:
where Cx is the sum of the resonant capacitance C1 and the parasitic capacitance CPARASITI in the resonant tank.
The capacitance detection chip 11 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 11 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 a resonant frequency of the resonant tank according to a frequency of the voltage signal or the current signal.
Referring to fig. 1 to 8, in an alternative embodiment, when the first electrode 20 is provided in plurality, the number of the resonant units 12 corresponds to the number of the first electrodes 20, and each resonant unit 12 is connected to a capacitor formed by the corresponding first electrode 20 and the heat exchange tube 100 at the corresponding position to form a resonant circuit. In this embodiment, the number of the first electrodes 20 may be three, and the three first electrodes 20 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 and the coil pipe form a second capacitor to detect the frosting change of the coil pipe and the output pipe orifice of the heat exchange pipe 100 in the heat exchange process, or the second capacitor is arranged on the heat exchange pipe 100 of the output pipe orifice to form a third capacitor to sense the frosting change of the output pipe orifice.
Each resonant unit 12 includes a resonant capacitor and a resonant inductor, and the circuit structure, the function, and the effects thereof can be found in the above embodiments, which are not described herein again.
In some embodiments, an RC filter circuit 13 is further disposed in series between the resonant tank and the capacitance detection chip 11, and the RC filter circuit 13 is used for filtering out noise in the resonant signal. The number of the RC filter circuits 13 may be one or multiple, and the RC filter circuits may be set correspondingly according to the number of the resonant circuits. In this embodiment, the number of the RC filter circuits 13 may be three, each RC filter circuit 13 includes a resistor and two capacitors, wherein the resistor is serially connected between the resonant circuit and the capacitance detection chip 11, one capacitor is serially connected between the capacitance detection chip 11 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 the heat exchange tube and the fin, wherein the heat exchanger frosting detection device is provided, a second signal end of the heat exchanger frosting detection device is connected with the heat exchange tube, and the first electrode is arranged on the heat exchange tube or the fin. 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.
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 present invention also provides a defrosting control method for an air conditioner, which is applied to the air conditioner as described above, and referring to fig. 9, the frosting detection method includes 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 detection device includes a first electrode, a resonance unit, and a capacitance detection chip, the first electrode and a heat exchange tube of the heat exchanger form a capacitor to sense a frost change on the heat exchange tube, the capacitor and the resonance unit form a resonance circuit, and a resonance frequency of the resonance circuit is detected by 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.
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 400 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 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. According to this feature, a first electrode is disposed on the refrigerant input pipe of the heat exchanger and forms a capacitor with the input pipe, so as to obtain a capacitance C1 when the outdoor heat exchanger starts to frost, and a first electrode is disposed on the refrigerant output pipe of the heat exchanger and forms a capacitor with the output pipe, so as to obtain a reference capacitance C0. The first electrode is affixed to the heat exchanger coil or fin 400 and forms a capacitor with the coil so that the value of the varying capacitance C2 can be detected during the frosting process of the heat exchanger.
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; the capacitance value of C2 detected by the frosting starting time T0 is recorded as C20, the difference value delta C2 between the variable capacitance value C2 and the reference capacitance value C20 in the frosting process of the heat exchanger is calculated, namely delta C2 is equal to C2-C20, the time corresponding to the capacitance difference value is obtained through a capacitance change-time curve C-T graph, and the time is the continuous frosting time T1 of the heat exchanger; the frosting time T of the heat exchanger can be obtained according to the frosting starting T0 and the frosting lasting time T1, namely T is T1-T0
The frosting thickness H can be calculated according to the following formula:
H＝ΔC2/K
the formula is an empirical formula of capacitance and frosting thickness, H is the current frosting thickness of the outdoor heat exchanger, delta C2 is the difference value between capacitance values C2 and C20 changed in the frosting process, 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.
Wherein the first defrosting start condition may be set that a frosting time of the outdoor heat exchanger is greater than a preset time threshold; the second frost start condition may be set such that the frosting thickness H of the outdoor heat exchanger is greater than the 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 outdoor heat exchanger is not frosted enough or the heat exchanger is not frosted due to serious frosting 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 (10)
1. A heat exchanger frost detection device, characterized in that, heat exchanger frost detection device includes:
the capacitance detection module is provided with a first signal end and a second signal end which is used for being connected with a heat exchange tube of the heat exchanger; the heat exchange tube comprises an input tube orifice, an output tube orifice and a coil;
the first electrode is connected with the first signal end and used for being arranged on a heat exchange tube or a fin of a heat exchanger so as to enable the first electrode and the heat exchange tube of the heat exchanger to form a capacitor, and when the first electrode is a metal polar plate, the metal polar plate is arranged on the fin of the heat exchanger and is opposite to the coil;
the capacitance detection module is configured to output a frosting detection signal of frosting of the heat exchanger when sensing the capacitance value change of the capacitor;
when the number of the first electrodes is multiple, the first electrodes are respectively arranged at the inlet pipe orifices of the heat exchange tubes, form first capacitors with the heat exchange tubes at the inlet pipe orifices, are fixed on coil pipes or fins of the heat exchanger, form second capacitors with the coil pipes, are arranged at the outlet pipe orifices of the heat exchange tubes, and form third capacitors with the heat exchange tubes at the outlet pipe orifices.
2. The heat exchanger frost detection apparatus of claim 1, wherein when the first electrode is an annular metal sleeve, the annular metal sleeve fits over the heat exchange tube sleeve.
3. The heat exchanger frost detection apparatus of claim 2, further comprising a first fixed base, wherein the annular metal sleeve is connected to the first fixed base, and wherein the annular metal sleeve is mounted on the heat exchanger via the first fixed base.
4. The frost detection apparatus of claim 3, wherein the first fixing base comprises two opposite clamping arms, and a clamping groove adapted to be clamped by the annular metal sleeve is formed between the two clamping arms.
5. The heat exchanger frost detection apparatus of claim 1, further comprising a second fixed base, wherein the metal plate is connected to the second fixed base, and the metal plate is mounted on a fin of the heat exchanger through the second fixed base.
6. The frost detection apparatus for a heat exchanger according to claim 5, wherein the second fixing base includes a bottom plate and a connecting portion for connecting to a fin of the heat exchanger, the connecting portion is provided on one side of the bottom plate, and the metal plate is embedded in the bottom plate.
7. The frost detection device of any of claims 1 to 6, wherein the capacitance detection module comprises a capacitance detection chip and a resonance unit, the resonance unit is electrically connected with the first electrode, and a heat exchange tube of the heat exchanger is grounded to form a resonance loop; two first signal input ends of the capacitance detection chip are connected with the resonance unit; wherein the content of the first and second substances,
the capacitance detection chip is used for detecting the resonant frequency of the resonant circuit and acquiring the capacitance value generated by the frosting detection sensor group according to the resonant frequency of the resonant circuit so as to generate a frosting detection signal.
8. A heat exchanger comprising a heat exchange tube, a fin, and the frost detection apparatus of the heat exchanger according to any of claims 1 to 7, wherein the second signal terminal of the frost detection apparatus of the heat exchanger is connected to the heat exchange tube, and the first electrode is mounted on the heat exchange tube or the fin.
9. An air conditioner characterized by comprising the heat exchanger according to claim 8.
10. A defrosting control method of an air conditioner applied to the air conditioner as claimed in claim 9, 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 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.
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| CN201810809313.XA CN109059356B (en) | 2018-07-20 | 2018-07-20 | Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner |
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| CN201810809313.XA CN109059356B (en) | 2018-07-20 | 2018-07-20 | Heat exchanger frosting detection device, heat exchanger, air conditioner and defrosting control method of air conditioner |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN87207535U (en) * | 1987-04-29 | 1987-12-31 | 王紫来 | Frost thickness capacitance sensor used in a refrigerating system |
| CN106989494A (en) * | 2017-05-10 | 2017-07-28 | 广东美的制冷设备有限公司 | Air conditioner and its frosting detection device and method |
| CN107388700A (en) * | 2017-01-20 | 2017-11-24 | 芯海科技（深圳）股份有限公司 | A kind of refrigerator coagulates white sensor |
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2018
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN87207535U (en) * | 1987-04-29 | 1987-12-31 | 王紫来 | Frost thickness capacitance sensor used in a refrigerating system |
| CN107388700A (en) * | 2017-01-20 | 2017-11-24 | 芯海科技（深圳）股份有限公司 | A kind of refrigerator coagulates white sensor |
| CN106989494A (en) * | 2017-05-10 | 2017-07-28 | 广东美的制冷设备有限公司 | Air conditioner and its frosting detection device and method |
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