Sedan air conditioner evaporator defrost device
Technical field
What the present invention relates to is a kind of sedan air conditioner evaporator defrost device, and particularly a kind of employing electric expansion valve is controlled the evaporator surface temperature as throttle mechanism by the aperture of control electric expansion valve, and the realization evaporator is not shut down the defroster device of defrost.Belong to the sedan air conditioner technical field.
Technical background
The sedan air conditioner system mainly contains parts such as compressor, condenser, evaporator, reservoir and throttle mechanism and forms.Common throttle part is heating power expansion valve and restriction sleeve, but heating power expansion valve and restriction sleeve all have common limitation.Be that in a single day structure fixs, its controlled target parameter and control law are determined, can't be changed.No matter be what object property treated, they are all worked in the same way, and this obviously is unfavorable for the adjusting of refrigerant flow and evaporating temperature.The sedan air conditioner system is in operation, because the amplitude that ambient temperature, solar radiation temperature, the speed of a motor vehicle etc. change is bigger, cause evaporating temperature to change greatly, the temperature of evaporator surface also changes thereupon, if the evaporator surface temperature is lower than the temperature of the dew point of surrounding air, will be in the evaporator surface frosting, when evaporating temperature does not change, then evaporator surface will further freeze, so that stop up evaporator, influence the heat exchange of evaporator, reduce the refrigerating capacity of evaporator, so just need be to evaporator defrost.
In the prior art, the sedan air conditioner Defrost method is at evaporator surface a temperature sensor to be housed, and the sedan air conditioner controller is according to the height of evaporator surface temperature, sends control signal and gives magnetic clutch, control compressor operating or stop.When the evaporator surface temperature was lower than 0 ℃, magnetic clutch and compressor disconnected, and began defrosting.After the compressor shutdown, the evaporator surface temperature rises, and frost melts gradually; When the evaporator surface temperature is higher than certain temperature value (being generally 4 ℃), magnetic clutch is connected compressor, begin refrigeration, Fraquent start compressor like this causes bigger impact to motorcar engine on the one hand, on the other hand to all having bigger influence in service life of traveling comfort, energy saving and the compressor of sedan air conditioner, especially less in the thermal load of car chamber, under the bigger operating mode of the refrigerating capacity of evaporator, the number of times of compressor start is more frequent, and the harm that is brought is just bigger.
Summary of the invention
For deficiency and the defective that overcomes prior art, avoid the harm that starts compressor continually and brought because of evaporator surface defrosting, the invention provides a kind of new defroster device, mainly comprise compressor, condenser, reservoir, electric expansion valve, evaporator fan, evaporator, the evaporator outlet temperature sensor, evaporator temperature sensor, evaporator surface temperature sensor, A/D converter, program store, the driving circuit of electric expansion valve, microprocessor.Throttle mechanism adopts electric expansion valve; when the evaporator surface temperature is lower than design temperature; microprocessor sends instruction, increases the pulse count of electric expansion valve, promptly increases the aperture of electric expansion valve; after the aperture of electric expansion valve increases; evaporating pressure rises, and evaporator surface temperature raises, when evaporator surface temperature is higher than design temperature; the frost of evaporator surface has then melted, and the realization evaporator is not shut down defrost.
Sedan air conditioner is in operation, adopt the regulating mechanism of electric expansion valve as the evaporator refrigerant flow, on the one hand normally in service, microprocessor is according to the size of evaporator superheat, suitably adjust the aperture of electric expansion valve, keep the degree of superheating of evaporator to equal setting value.When detecting the evaporator surface temperature, microprocessor is lower than when setting the frosting temperature, microprocessor sends instruction, increase the aperture of electric expansion valve, evaporator surface temperature is risen, when the evaporator surface temperature greater than a certain temperature value (as 4 ℃), defrosting finishes, and microprocessor control electric expansion valve enters normal operation scheme.This defroster device has been avoided the frequent starting of compressor, reduces energy consumption, has increased the stability of system, is easy to realize the Based Intelligent Control of sedan air conditioner.
Description of drawings
Fig. 1 is a sedan air conditioner evaporator defrost device scheme drawing
1 is compressor among the figure, and 2 is condenser, and 3 is reservoir, 4 is electric expansion valve, 5 is evaporator fan, and 6 is evaporator, and 7 is the evaporator outlet temperature sensor, 8 is the evaporator temperature sensor, 9 is the evaporator surface temperature sensor, and 10 is A/D converter, and 11 is memory device, 12 is the driving circuit of electric expansion valve, and 13 is microprocessor.
The specific embodiment
Below in conjunction with accompanying drawing concrete enforcement of the present invention is further described.
As shown in Figure 1, the present invention mainly comprises compressor 1, condenser 2, reservoir 3, electric expansion valve 4, evaporator fan 5, evaporator 6, evaporator outlet temperature sensor 7, evaporator temperature sensor 8, evaporator surface temperature sensor 9, A/D converter 10, program store 11, the driving circuit 12 of electric expansion valve, microprocessor 13.The outlet of compressor 1 links to each other with condenser 2 imports, the outlet of condenser 2 links to each other with the import of reservoir 3, the outlet of reservoir 3 links to each other with the import of electric expansion valve 4, and the outlet of electric expansion valve 4 connects the import of evaporator 6, and the outlet of evaporator 6 connects the import of compressor 1.Temperature sensor 8 is close on the tube wall of evaporator 6 imports, and the mouth of temperature sensor 8 is electrically connected with the input end of A/D converter 10; Temperature sensor 7 is close on the tube wall of evaporator 6 outlets, and the mouth of temperature sensor 7 is electrically connected with the input end of A/D converter 10; Temperature sensor 9 is close on the wall of evaporator 6, and the mouth of temperature sensor 9 is electrically connected with the input end of A/D converter 10.The mouth of A/D converter 10 links to each other with RAM in the microprocessor 13, program store 11 is electrically connected with microprocessor 13, the input end of the driving circuit 12 of electric expansion valve is electrically connected with microprocessor 13 mouths, and the mouth of electronic expansion valve-driving circuit 12 is electrically connected with electric expansion valve 4.
High temperature, the higher pressure refrigerant gas of coming out from compressor 1, after condenser 2 condensations, enter reservoir 3, by the throttling action of electric expansion valve 4, refrigerant pressure is reduced to evaporating pressure then, enter evaporator 6, evaporation absorbs heat in evaporator 6, become gas, refrigerant gas is got back to compressor 1, finishes a refrigerating cycle.In degree of superheating control, temperature sensor 8,7 detect advancing of evaporator respectively, temperature out, both heal differentials are as the degree of superheating of evaporator, when temperature sensor 7,8 analog signal is converted into digital signal through AD converter 10, send microprocessor 13, microprocessor 13 according to the temperature signal of sending here and and be stored in the control algorithm (as PID control or fuzzy control) of memory device 11 in advance, draw the needed pulse count of certain aperture of corresponding electric expansion valve 4, send into driving circuit 12, the aperture of control electric expansion valve 4, thereby the degree of superheating of control evaporator 6.
Rotating speed less when the load of car chamber or compressor 1 becomes big suddenly, and the evaporating pressure in the evaporator 6 descends, and the surface temperature of evaporator 6 reduces.Evaporator 6 surface temperature sensors 9 send A/D converter 10 with the signal that detects, A/D converter 10 is converted into digital signal with analog signal, the digital signal that microprocessor 13 detects according to temperature sensor 9, judge whether evaporator 6 surface temperatures are lower than the frosting temperature of setting (as 0 ℃), if evaporator 6 surface temperatures are lower than design temperature, then microprocessor 13 sends the driving circuit 12 that electric expansion valve is given in instruction, increase the aperture of electric expansion valve 4, improve evaporating pressure, the surface temperature of evaporator 6 is raise, and defrost begins.When the surface temperature of evaporator 6 was raised to a certain setting value (as 4 ℃), defrost finished.Microprocessor 13 sends control command, and the control of electric expansion valve 4 enters normal control program, promptly according to the heal differential of evaporator 6 inlet temperature sensors 8 and outlet temperature sensor 7 measurements, controls the degree of superheating of evaporator 6.The harm that frequent starting compressor 1 is brought when so just having avoided evaporator 6 defrostings.