CN116928106B - Temperature control method and system for oil-free screw compressor - Google Patents

Temperature control method and system for oil-free screw compressor Download PDF

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Publication number
CN116928106B
CN116928106B CN202311194633.6A CN202311194633A CN116928106B CN 116928106 B CN116928106 B CN 116928106B CN 202311194633 A CN202311194633 A CN 202311194633A CN 116928106 B CN116928106 B CN 116928106B
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temperature
function
detection period
fan
data
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CN116928106A (en
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张博
程建勇
朱汪
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Denair Energy Equipment Co ltd
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Denair Energy Equipment Co ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
    • F04C29/04—Heating; Cooling; Heat insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D27/00—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids
    • F04D27/004—Control, e.g. regulation, of pumps, pumping installations or pumping systems specially adapted for elastic fluids by varying driving speed

Abstract

The invention provides a temperature control method and a temperature control system for an oil-free screw compressor, and relates to the field of temperature control. The method comprises the following steps: detecting a first temperature number of a vent window of a case of the oil-free screw compressor and second temperature data above the oil-free screw compressor; determining first rotational speed data of the oil-free screw compressor and second rotational speed data of the fan; obtaining a predicted temperature according to the first temperature data and the second temperature data; determining whether the radius of the belt pulley needs to be adjusted according to the predicted temperature; if the radius of the belt pulley needs to be adjusted, predicting third rotation speed data of the fan according to the second temperature data, the predicted temperature and the second rotation speed data; and determining the radius of the target belt pulley and the target belt pulley according to the third rotating speed data and the first rotating speed data, and switching to the target belt pulley. According to the invention, the heat dissipation efficiency can be improved, and the temperature of the interior of the case in the next detection period can be controlled within a reasonable range.

Description

Temperature control method and system for oil-free screw compressor
Technical Field
The invention relates to the technical field of temperature control, in particular to a temperature control method and system of an oil-free screw compressor.
Background
The oil-free screw compressor can generate a large amount of heat during operation, so that a fan is required to be installed in a case of the oil-free screw compressor, heat in the case can be discharged out of the case, air with lower temperature is introduced, the temperature in the case is kept at a proper level, heat accumulation is reduced, the temperature is overhigh, and further the efficiency of the oil-free screw compressor is reduced or even fails. In the related art, the fan may be driven by the motor, and this driving method requires additional installation of the motor and additional power consumption, resulting in increased cost, more complex internal structure of the cabinet, and reduced reliability.
The information disclosed in the background section of the application is only for enhancement of understanding of the general background of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The application provides a temperature control method and a temperature control system for an oil-free screw compressor, which can control the temperature in a case of the oil-free screw compressor, keep the temperature in a reasonable range and solve the problems of rising cost and lowering reliability.
According to a first aspect of the present invention, there is provided a temperature control method of an oil-free screw compressor, comprising:
detecting a plurality of first temperature data by a first temperature sensor disposed at a discharge window of a casing of the oil-free screw compressor and a plurality of second temperature data by a second temperature sensor disposed above the oil-free screw compressor in the casing at a plurality of times of an i-th detection period;
determining first rotation speed data of the oil-free screw compressor in an ith detection period and second rotation speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
if the radius of the belt pulley needs to be adjusted, predicting third rotating speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotating speed data;
Determining a target pulley radius according to the third rotation speed data and the first rotation speed data;
and determining a target belt pulley according to the radius of the target belt pulley, and controlling the belt to be switched to the target belt pulley.
According to one embodiment of the present invention, predicting a predicted temperature above the oil-free screw compressor in the casing at the end of the (i+1) th detection cycle based on the first temperature data and the second temperature data comprises:
fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments;
fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments;
performing difference on the first temperature function and the second temperature function to obtain a first difference function;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function;
and if the heat rejection capability of the fan is saturated, predicting the predicted temperature above the oil-free screw compressor in the case at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function.
According to one embodiment of the invention, determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function, and the first difference function comprises:
acquiring a first derivative function of the first temperature function;
obtaining a second derivative function of the second temperature function;
obtaining a third derivative function of the first difference function;
if the first, second and third guide functions satisfy the first, second and third conditions C1, C2 and C3 simultaneously, determining that the heat rejection capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈>For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function.
According to one embodiment of the invention, predicting a predicted temperature above the oil-free screw compressor in the housing at the end of the i+1th detection cycle based on said first temperature function, said second temperature function and said first difference function if the heat rejection capacity of the fan is saturated comprises:
Determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time;
and if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function.
According to one embodiment of the invention, if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time comprises:
according to the formula
，
Determining a predicted temperatureWherein, the method comprises the steps of, wherein,t 1,A for the first target moment of time in question,f 2 as a second temperature function, +.>A second derivative function that is a second temperature function,t i ,m+1 the mth time of the (i+1) th detection period is the mth time of the (i+1) th detection period, and the mth time is the end time of the (i+1) th detection period.
According to one embodiment of the present invention, if the radius of the pulley needs to be adjusted, predicting the third rotation speed data of the fan of the (i+1) th detection cycle according to the second temperature data, the predicted temperature and the second rotation speed data, includes:
Determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan;
determining a volume multiple according to the air volume and the volume of the case;
and predicting third rotating speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotating speed data.
According to an embodiment of the present invention, predicting third rotation speed data of the fan of the (i+1) th detection cycle according to the volume multiple, the second temperature data, the predicted temperature, and the second rotation speed data includes:
according to the formula
，
Determining the third rotational speed datan 3 Wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
According to a second aspect of the present invention there is provided an oil free screw compressor temperature control system, the system comprising:
the detection module is used for detecting a plurality of first temperature data through a first temperature sensor arranged at an exhaust window of a case of the oil-free screw compressor at a plurality of moments of an ith detection period and detecting a plurality of second temperature data through a second temperature sensor arranged above the oil-free screw compressor in the case;
The rotating speed module is used for determining first rotating speed data of the oil-free screw compressor in an ith detection period and second rotating speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
the predicted temperature module is used for predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
the judging module is used for determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
the predicted rotating speed module is used for predicting the third rotating speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotating speed data if the radius of the belt pulley needs to be adjusted;
the radius module is used for determining the radius of the target belt pulley according to the third rotating speed data and the first rotating speed data;
and the switching module is used for determining a target belt pulley according to the radius of the target belt pulley and controlling the belt to be switched to the target belt pulley.
According to one embodiment of the invention, the predicted temperature module is further configured to:
fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments;
fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments;
performing difference on the first temperature function and the second temperature function to obtain a first difference function;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function;
and if the heat rejection capability of the fan is saturated, predicting the predicted temperature above the oil-free screw compressor in the case at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
acquiring a first derivative function of the first temperature function;
obtaining a second derivative function of the second temperature function;
Obtaining a third derivative function of the first difference function;
if the first, second and third guide functions satisfy the first, second and third conditions C1, C2 and C3 simultaneously, determining that the heat rejection capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈>For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time;
and if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
According to the formula
，
Determining a predicted temperatureWherein, the method comprises the steps of, wherein,t 1,A for the first target moment of time in question,f 2 as a second temperature function, +.>A second derivative function that is a second temperature function,t i ,m+1 the mth time of the (i+1) th detection period is the mth time of the (i+1) th detection period, and the mth time is the end time of the (i+1) th detection period.
According to one embodiment of the invention, the predicted rotational speed module is further configured to:
determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan;
determining a volume multiple according to the air volume and the volume of the case;
and predicting third rotating speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotating speed data.
According to one embodiment of the invention, the predicted rotational speed module is further configured to:
according to the formula
，
Determining the third rotational speed datan 3 Wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
According to a third aspect of the present invention, there is provided an oil-free screw compressor temperature control apparatus comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored by the memory to perform the oil-free screw compressor temperature control method.
According to a fourth aspect of the present invention there is provided a computer readable storage medium having stored thereon computer program instructions which when executed by a processor implement the oil free screw compressor temperature control method.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the fan can be directly driven by the engine of the oil-free screw compressor, an additional driving motor is not required to be installed, the electric quantity is not additionally consumed, the heat dissipation cost is reduced, the internal structure of the case is simple, and the reliability of the oil-free screw compressor is improved. And the temperature of the next detection period can be predicted, if the temperature exceeds a reasonable range, the third rotating speed data of the fan of the next detection period can be predicted, and the belt connecting the fan transmission shaft and the engine main shaft is switched to the target belt pulley, so that the air quantity of the fan is changed, the heat radiation efficiency is improved, and the temperature of the inside of the case in the next detection period can be controlled in the reasonable range. When the predicted temperature in the case at the end of the (i+1) th detection period is predicted, the relation between the first target time and the end time of the (i+1) th detection period can be determined, the predicted temperature above the oil-free screw compressor in the case can be predicted according to the relation and the temperature change rule in the case, and the accuracy of the predicted temperature is improved. When the third rotation speed data is determined, the volume multiple can be determined in an equivalent mode, and then the third rotation speed data is determined through the proportional relation between the temperature rise amplitude and the rotation speed and the volume multiple, so that the accuracy of the third rotation speed data is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. Other features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments of the invention or the solutions of the prior art, the drawings which are necessary for the description of the embodiments or the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other embodiments may be obtained from these drawings without inventive effort to a person skilled in the art,
fig. 1 exemplarily shows a flow diagram of a temperature control method of an oil-free screw compressor according to an embodiment of the present invention;
fig. 2 schematically shows a block diagram of an oil-free screw compressor temperature control system according to an embodiment of the invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
Fig. 1 exemplarily shows a flow diagram of a temperature control method of an oil-free screw compressor according to an embodiment of the present invention, the method including:
step S101, detecting a plurality of first temperature data through a first temperature sensor arranged at an exhaust window of a case of the oil-free screw compressor at a plurality of moments of an ith detection period, and detecting a plurality of second temperature data through a second temperature sensor arranged above the oil-free screw compressor in the case;
step S102, determining first rotation speed data of the oil-free screw compressor in an ith detection period and second rotation speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
step S103, predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
Step S104, determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
step S105, if the radius of the belt pulley needs to be adjusted, predicting third rotation speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotation speed data;
step S106, determining the radius of the target belt pulley according to the third rotating speed data and the first rotating speed data;
and step S107, determining a target belt pulley according to the radius of the target belt pulley, and controlling the belt to be switched to the target belt pulley.
According to the temperature control method of the oil-free screw compressor, disclosed by the embodiment of the invention, the fan can be directly driven by the engine of the oil-free screw compressor, an additional driving motor is not required to be installed, the electric quantity is not additionally consumed, the heat dissipation cost is reduced, the internal structure of the case is simple, and the reliability of the oil-free screw compressor is improved. And the temperature of the next detection period can be predicted, if the temperature exceeds a reasonable range, the third rotating speed data of the fan of the next detection period can be predicted, and the belt connecting the fan transmission shaft and the engine main shaft is switched to the target belt pulley, so that the air quantity of the fan is changed, the heat radiation efficiency is improved, and the temperature of the inside of the case in the next detection period can be controlled in the reasonable range.
According to one embodiment of the invention, the oil-free screw compressor can be arranged in the case, the case can be provided with the air inlet window and the air outlet window, the fan can be arranged at the air outlet window, when the fan rotates, the air heated by the oil-free screw compressor in the case can be discharged out of the case, and meanwhile, the external cold air can enter the case through the air inlet window, so that the purposes of ventilation and heat dissipation of the inside of the case are achieved.
According to one embodiment of the invention, the engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on the transmission shaft of the fan through a belt, and when the engine of the oil-free screw compressor rotates, the fan can be driven to rotate in a belt transmission mode, so that the fan ventilates the case. After the belt is connected with the main shaft of the engine and the belt pulley on the fan transmission shaft, the ratio of the rotating speed of the engine to the rotating speed of the fan is fixed, so that the rotating speed of the fan can be adjusted only by changing the rotating speed of the engine or switching the belt pulley, and the heat generated by the engine can be changed at the same time by changing the rotating speed of the engine, so that the temperature control mode in the case is more complex, and therefore, if the heat generated by the oil-free screw compressor is excessive, the current rotating speed of the fan is difficult to keep the temperature in the case in a reasonable range, the belt pulley can be switched, so that the rotating speed of the fan is changed, the air quantity is increased, the temperature in the case can be controlled in a reasonable range, the oil-free screw compressor can normally run, and the failure rate is reduced. The pulley is switched to change the rotation speed of the fan, and the power requirement of the fan is increased, so that the power output of the engine of the oil-free screw compressor is increased, but the heat generated by the oil-free screw compressor is not greatly influenced due to the light weight of the fan and the low power requirement, so that the complexity of temperature control is reduced.
According to an embodiment of the present invention, in step S101, each detection period may be set to 1 minute, 3 minutes, etc., and the present invention does not limit the duration of the detection period. Each detection period can comprise a plurality of moments, each moment can be separated by 1 second, 3 seconds and the like, and the time interval between the moments is not limited by the invention. The first temperature sensor may be disposed at the discharge window, may detect first temperature data of hot air discharged from the fan, and heat of the hot air may be generated by the oil-free screw compressor and directly sucked by the fan and discharged out of the cabinet, and thus, the temperature of the hot air may be higher than that of the inside of the cabinet. A second temperature sensor disposed within the chassis above the oil-free screw compressor may detect second temperature data within the chassis that may remain at a relatively constant level if the heat dissipation efficiency of the fan is sufficient, and that is generally lower than the first temperature data. However, if the heat dissipation efficiency of the fan is insufficient, that is, all heat generated by the oil-free screw compressor cannot be discharged, heat in the case may be accumulated, so that the temperature in the case rises, the second temperature data may gradually approach the first temperature data, and finally the first temperature data and the second temperature data are equal, that is, the temperature of air in the case and the temperature of air discharged from the case are equal, so that the inside of the case cannot be kept in a reasonable temperature range, and the possibility of failure of the oil-free screw compressor is increased.
According to an embodiment of the present invention, in step S102, the first rotational speed data of the oil-free screw compressor and the second rotational speed data of the fan in the ith detection period may be determined, and since the engine main shaft of the oil-free screw compressor is directly connected to the pulley provided on the transmission shaft of the fan through the belt, the ratio between the first rotational speed data and the second rotational speed data is fixed.
According to an embodiment of the present invention, in step S103, the predicted temperature above the oil-free screw compressor in the casing at the end of the (i+1) th detection period may be predicted based on the first temperature data and the second temperature data, so that it may be determined whether the temperature in the casing in the (i+1) th detection period may be maintained within a reasonable range based on the predicted temperature, and if the temperature can be maintained within a reasonable range, the operation and detection of the (i+1) th detection period may be directly started without any adjustment, and if the temperature cannot be maintained within a reasonable range, the fan rotation speed may be adjusted to improve the heat dissipation efficiency, i.e., a pulley connected to a belt may be switched, thereby adjusting the fan rotation speed.
According to one embodiment of the present invention, step S103 may include: fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments; fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments; performing difference on the first temperature function and the second temperature function to obtain a first difference function; determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function; and if the heat rejection capability of the fan is saturated, predicting the predicted temperature above the oil-free screw compressor in the case at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function.
According to one embodiment of the present invention, the first temperature data and the second temperature data may not change linearly, for example, the first temperature data and the second temperature data increase faster and faster due to the accumulation effect of heat, so that a quadratic polynomial fitting, or other form of nonlinear function may be used to perform the fitting during the fitting process to obtain the first temperature function and the second temperature function, respectively, and the present invention is not limited to the specific manner of fitting.
According to one embodiment of the present invention, after the first temperature function and the second temperature function are obtained, the first temperature function and the second temperature function may be subjected to a difference to obtain a first difference function, so that it is determined whether the heat discharging capability of the fan is saturated, that is, whether the heat generated by the oil-free screw compressor can be discharged without accumulating in the casing, that is, whether the temperature in the casing can be kept within a reasonable range in a future detection period, if the heat discharging capability of the fan is saturated, the temperature in the casing cannot be kept within a reasonable range in a future detection period, otherwise, if the heat discharging capability of the fan is not saturated, the temperature in the casing can be kept within a reasonable range in a future detection period.
According to one embodiment of the invention, determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function, and the first difference function comprises: acquiring a first derivative function of the first temperature function; obtaining a second derivative function of the second temperature function; obtaining a third derivative function of the first difference function; determining that the heat extraction capacity of the fan is saturated if the first, second and third guide functions simultaneously satisfy a first condition C1, a second condition C2 and a third condition C3, wherein the first, second and third guide functions simultaneously satisfy the first, second and third conditions C1, C2 and C3, and the heat extraction capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is +.>，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈>For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function.
According to one embodiment of the present invention, the first temperature function, the second temperature function and the first difference function may be respectively derived, and a first derivative function, a second derivative function and a third derivative function may be respectively obtained. Wherein the first derivative function may be used to represent a rate of change of the function value of the first temperature function, i.e. a rate of change of the first temperature data, and the second derivative function may be used to represent a rate of change of the function value of the second temperature function, i.e. a rate of change of the second temperature data, and the first difference function may be used to represent a rate of change of the function value of the first difference function, i.e. a rate of change of a difference between the first temperature data and the second temperature data.
According to an embodiment of the present invention, it may be determined whether the first, second and third functions can satisfy the first, second and third conditions at the same time. The first condition is that the function value of the first derivative function at the ending time of the ith detection period is greater than 0, which indicates that the first temperature data presents an ascending trend at the ending time of the ith detection period. The second condition is that the function value of the second derivative function at the end time of the ith detection period is greater than 0, which indicates that the second temperature data presents a rising trend at the end time of the ith detection period. The third condition is that the function value of the third derivative function at the end time of the ith detection period is smaller than 0, which indicates that the difference between the first temperature data and the second temperature data shows a tendency of shrinking. If the first condition C1, the second condition C2 and the third condition C3 are satisfied at the same time, it means that the temperatures in the casing and at the casing exhaust window are both rising, and the temperature rise is faster due to the insufficient heat dissipation efficiency of the fan, the temperature at the casing exhaust window is the temperature of the surrounding air heated by the heat released from the oil-free screw compressor (sucked to the exhaust window by the fan), and therefore, the heat around the oil-free screw compressor is not accumulated, and the temperature rise speed at the exhaust window is slower than the temperature rise speed in the casing, so that the difference between the first temperature data and the second temperature data presents a trend of shrinking.
According to one embodiment of the present invention, if the heat discharging capability of the fan is not saturated, the temperature in the (i+1) th detection period can be maintained within a reasonable range, so that temperature prediction is not required, and the rotation speed of the fan is not required to be changed. If the heat removal capacity of the fan is saturated, the predicted temperature in the chassis at the end of the (i+1) th detection period can be predicted, so that whether the predicted temperature is within a reasonable range or not can be determined, if the predicted temperature is beyond the reasonable range, the fan rotating speed can be changed to improve the heat removal efficiency, if the predicted temperature is still within the reasonable range, the fan rotating speed can be not required to be changed immediately, and if the predicted temperature exceeds the reasonable range at the end of a certain detection period in the future, the fan rotating speed can be changed.
According to one embodiment of the invention, predicting a predicted temperature above the oil-free screw compressor in the housing at the end of the i+1th detection cycle based on said first temperature function, said second temperature function and said first difference function if the heat rejection capacity of the fan is saturated comprises: determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function; if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time; and if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function.
According to one embodiment of the present invention, when the function value of the first difference function is 0, the temperatures in the case and at the exhaust window are equal, in which case it is difficult for the fan to discharge all the heat generated by the oil-free screw compressor, so that the heat accumulated in the case is excessive, resulting in temperature equalization at various positions (for example, at the exhaust window and above the oil-free screw compressor) in the case, the temperature at various positions in the case is the same as the temperature of the air around the oil-free screw compressor, in which case the temperature of the hot air discharged by the fan is the temperature of the air at various positions in the case, and thus the temperature at the exhaust window and above the oil-free screw compressor are equal. And, because the fan can't discharge all heat for the temperature in the quick-witted incasement can rise continuously, after the moment that the function value of first difference function is 0, the temperature that the exhaust window department will keep unanimous with oil-free screw compressor top, and the rising speed of temperature will also tend to unanimous.
According to one embodiment of the invention, if the first target instant is earlier than or equal to the end instant of the i+1th detection cycle, the temperatures at the discharge louver and above the oil-free screw compressor will always be equal after the first target instant and before the end instant of the i+1th detection cycle, together with the temperature rise.
According to one embodiment of the invention, if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time comprises: determining the predicted temperature according to equation (1)，
（1）
Wherein,t 1,A for the first target moment of time in question,f 2 as a function of a second temperature，A second derivative function that is a second temperature function,t i ,m+1 the mth time of the (i+1) th detection period is the mth time of the (i+1) th detection period, and the mth time is the end time of the (i+1) th detection period.
According to one embodiment of the invention, the first target time can be substituted into the second temperature function, so that the temperature in the case at the first target time can be determined, further, after the first target time, the temperature at the exhaust window and above the oil-free screw compressor are always equal, and the temperature rise is common, therefore, after the first target time, the temperature rise speed of each part in the case is kept consistent, the change rate of the second temperature function with a larger change rate (namely, the function value of the second derivative function at the first target time) can be approximately used as the change rate of the temperature in the case after the first target time, the temperature change amplitude in the time period between the first target time and the ending time of the i+1st detection period is the product of the change rate and the time period, and the predicted temperature above the oil-free screw compressor in the case at the ending of the i+1st detection period can be obtained by summing the product and the function value of the second temperature function at the first target time.
According to one embodiment of the present invention, if the first target time is later than the end time of the i+1th detection period, the function value of the second temperature function is still lower than the function value of the first temperature function at the end time of the i+1th detection period, and the two function values are not equal, so that the end time of the i+1th detection period can be substituted into the second temperature function, and the predicted temperature above the oil-free screw compressor in the casing at the end of the i+1th detection period can be determined.
By the method, the relation between the first target time and the ending time of the (i+1) th detection period can be determined, the predicted temperature above the oil-free screw compressor in the case can be predicted according to the relation and the temperature change rule in the case, and the accuracy of the predicted temperature is improved.
According to an embodiment of the present invention, in step S104, it may be determined whether the predicted temperature is within a reasonable range, if the predicted temperature is too high, it may be determined that the rotation speed of the fan needs to be adjusted, and since the fan is directly connected to the engine of the oil-free screw compressor through the belt, the radius of the pulley may be changed, i.e., switched to an appropriate pulley, while the rotation speed of the engine of the oil-free screw compressor is maintained, thereby increasing the rotation speed of the fan and improving the heat dissipation efficiency. Conversely, if the predicted temperature is within a reasonable range, then there may be no need to adjust the fan speed, nor to switch pulleys.
According to one embodiment of the present invention, in step S105, a fan speed that maintains the temperature of the (i+1) th detection cycle in the cabinet within a reasonable range may be first determined, and then an appropriate pulley may be selected based on the fan speed.
According to one embodiment of the present invention, step S105 may include: determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan; determining a volume multiple according to the air volume and the volume of the case; and predicting third rotating speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotating speed data.
According to one embodiment of the present invention, during a detection period, the volume of air flowing through the cross section of the fan is positively correlated with the cross section radius and the rotational speed of the fan, the cross section radius of the fan can be obtained according to the design parameters of the fan, and the volume of air flowing through the cross section of the fan during a detection period can be determined based on the current second rotational speed data of the fan, and in an example, the volume of air flowing through the cross section of the fan during a detection period can be determined according to formula (2):
（2）
Wherein,V f for the volume of air flowing through the fan section during a test cycle,ris the radius of the cross section of the fan,n 2 for the second rotational speed data, t is the duration of one detection cycle.
According to one embodiment of the invention, the volume factor may be determined by the ratio of the volume of air flowing through the fan section to the volume of the chassis over a detection period, and in an example, the volume factor may be determined according to equation (3):
（3）
wherein B is the volume multiple, and V is the volume of the case.
According to one embodiment of the present invention, after the above volume multiple is determined, third rotation speed data of the fan of the (i+1) th detection period may be determined based on the volume multiple, the second temperature data, the predicted temperature, and the second rotation speed data, where the third rotation speed data is a rotation speed at which the temperature in the cabinet is maintained within a reasonable range in the (i+1) th detection period.
According to one embodiment of the invention, the rotational speed of the fan is inversely related to the temperature rising speed in the case, i.e. the faster the rotational speed of the fan, the higher the heat dissipation efficiency, and the slower the temperature rising speed in the case. Target fan rotation speed capable of keeping temperature in the case unchanged can be presetn 0 The larger the difference between the actual rotation speed of the fan and the target rotation speed of the fan, the faster the temperature rise speed in the case, and therefore, the fan rotation speed is n 2 At the moment, the difference from the target fan rotating speed isn 0 -n 2 And the temperature change amplitude in the case in the (i+1) th detection period isWherein->In order to provide the predicted temperature for the temperature,T i,2,m is the second temperature data at the end time of the ith detection period. At the fan speed, the volume of air flowing through the section of the fan isV f Also isBVAt the (i+1) thThe temperature of the air with the volume V in the cabinet at the end of the detection period is +.>The temperature change range is->And the temperature of the air with the volume V in the case at the beginning time of the (i+1) th detection period isT i,2,m The temperature variation range is 0, so that the average temperature variation range of all the air flowing through the fan section in the detection period is +.>。
On the other hand, it is considered that when the fan rotation speed is 0, the volume of air flowing through the fan cross section is 0, and therefore, the heat generated by the oil-free screw compressor in one detection cycle heats only the air having the volume V in the casing, and the same heat heats the air having the volume V as described aboveBVWhen the air of (2) is heated, the average temperature change amplitude of the air isTherefore, when heating the air with the volume V, the average temperature change amplitude of the air with the volume V is +. >. In this case, the difference between the fan speed and the target fan speed is equal ton 0 . Therefore, based on the correspondence between the average variation amplitude of the temperature and the rotational speed difference between the fan rotational speed and the target table fan rotational speed, the following formula (4) can be obtained: />
（4）
The reduction can be obtained by the formula (5):
（5）
finishing the available formula (6):
（6）
according to one embodiment of the present invention, in order to control the temperature in the casing within a reasonable range in the (i+1) th detection period, a temperature threshold may be set, and at the end of the (i+1) th detection period, the temperature in the casing is made to be lower than or equal to the temperature threshold, and based on the above relationship between the rotational speed and the temperature increase amplitude, it may be assumed that the rotational speed of the fan is the third rotational speed datan 3 At the end of the (i+1) th detection period, the temperature in the case is the temperature thresholdT T The temperature change amplitude of the air in the case isT T -T i,2,m The average temperature change amplitude of the air flowing through the fan section is. Correspondingly, when the fan rotating speed is the second rotating speed data, the temperature in the case at the end time of the (i+1) th detection period is +.>The temperature change amplitude of the air in the case is +.>The average temperature variation amplitude of the air flowing through the fan section is +.>。
According to an embodiment of the present invention, based on the correspondence between the above average temperature variation amplitude of the air and the rotational speed difference between the fan rotational speed and the target fan rotational speed, the following formula (7) may be given:
（7）
That is, the ratio of the temperature difference between the temperature threshold and the second temperature data at the end time of the i-th detection period to the temperature difference between the predicted temperature and the second temperature data at the end time of the i-th detection period is equal to the ratio of the rotation speed difference between the target rotation speed and the third rotation speed data to the rotation speed difference between the target rotation speed and the second rotation speed data.
The formula (8) is obtained by sorting the formula (6) and the formula (7):
（8）
wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
Accordingly, predicting third rotational speed data of the fan for the (i+1) -th detection cycle based on the volume multiple, the second temperature data, the predicted temperature, and the second rotational speed data, includes: determining the third rotational speed data according to the above equation (8)n 3 。
In this way, the volume multiple can be determined in an equivalent way, and then the third rotation speed data can be determined through the proportional relation between the temperature rise amplitude and the rotation speed and the volume multiple, so that the accuracy of the third rotation speed data is improved.
According to one embodiment of the present invention, in step S106, the radius of the target pulley may be determined according to a ratio of the third rotational speed data and the first rotational speed data, which is inversely proportional to a ratio of the radius of the target pulley to the radius of the engine main shaft, and the radius of the target pulley may be determined based on the proportional relationship.
According to an embodiment of the present invention, in step S107, a plurality of pulleys may be mounted on the driving shaft of the fan, and a pulley having a radius smaller than the radius of the target pulley and closest to the radius of the target pulley may be selected as the target pulley, so that the belt may be switched to the target pulley such that the rotational speed of the fan reaches the third rotational speed data in the i+1th detection period.
According to the temperature control method of the oil-free screw compressor, disclosed by the embodiment of the invention, the fan can be directly driven by the engine of the oil-free screw compressor, an additional driving motor is not required to be installed, the electric quantity is not additionally consumed, the heat dissipation cost is reduced, the internal structure of the case is simple, and the reliability of the oil-free screw compressor is improved. And the temperature of the next detection period can be predicted, if the temperature exceeds a reasonable range, the third rotating speed data of the fan of the next detection period can be predicted, and the belt connecting the fan transmission shaft and the engine main shaft is switched to the target belt pulley, so that the air quantity of the fan is changed, the heat radiation efficiency is improved, and the temperature of the inside of the case in the next detection period can be controlled in the reasonable range. When the predicted temperature in the case at the end of the (i+1) th detection period is predicted, the relation between the first target time and the end time of the (i+1) th detection period can be determined, the predicted temperature above the oil-free screw compressor in the case can be predicted according to the relation and the temperature change rule in the case, and the accuracy of the predicted temperature is improved. When the third rotation speed data is determined, the volume multiple can be determined in an equivalent mode, and then the third rotation speed data is determined through the proportional relation between the temperature rise amplitude and the rotation speed and the volume multiple, so that the accuracy of the third rotation speed data is improved.
Fig. 2 schematically illustrates a block diagram of an oil-free screw compressor temperature control system according to an embodiment of the invention, the system comprising:
the detection module is used for detecting a plurality of first temperature data through a first temperature sensor arranged at an exhaust window of a case of the oil-free screw compressor at a plurality of moments of an ith detection period and detecting a plurality of second temperature data through a second temperature sensor arranged above the oil-free screw compressor in the case;
the rotating speed module is used for determining first rotating speed data of the oil-free screw compressor in an ith detection period and second rotating speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
the predicted temperature module is used for predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
the judging module is used for determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
the predicted rotating speed module is used for predicting the third rotating speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotating speed data if the radius of the belt pulley needs to be adjusted;
The radius module is used for determining the radius of the target belt pulley according to the third rotating speed data and the first rotating speed data;
and the switching module is used for determining a target belt pulley according to the radius of the target belt pulley and controlling the belt to be switched to the target belt pulley.
According to one embodiment of the invention, the predicted temperature module is further configured to:
fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments;
fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments;
performing difference on the first temperature function and the second temperature function to obtain a first difference function;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function;
and if the heat rejection capability of the fan is saturated, predicting the predicted temperature above the oil-free screw compressor in the case at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
acquiring a first derivative function of the first temperature function;
obtaining a second derivative function of the second temperature function;
obtaining a third derivative function of the first difference function;
if the first, second and third guide functions satisfy the first, second and third conditions C1, C2 and C3 simultaneously, determining that the heat rejection capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈>For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time;
And if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function.
According to one embodiment of the invention, the predicted temperature module is further configured to:
according to the formula
Determining a predicted temperatureWherein, the method comprises the steps of, wherein,t 1,A for the first target moment of time in question,f 2 as a second temperature function, +.>A second derivative function that is a second temperature function,t i ,m+1 the mth time of the (i+1) th detection period is the mth time of the (i+1) th detection period, and the mth time is the end time of the (i+1) th detection period.
According to one embodiment of the invention, the predicted rotational speed module is further configured to:
determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan;
determining a volume multiple according to the air volume and the volume of the case;
and predicting third rotating speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotating speed data.
According to one embodiment of the invention, the predicted rotational speed module is further configured to:
according to the formula
/>
Determining the third rotational speed data n 3 Wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
According to an embodiment of the present invention, there is provided an oil-free screw compressor temperature control apparatus including: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored by the memory to perform the oil-free screw compressor temperature control method.
According to one embodiment of the present invention, a computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the oil free screw compressor temperature control method is provided.
The present invention may be a method, apparatus, system, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for performing various aspects of the present invention.
It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are by way of example only and are not limiting. The objects of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been shown and described in the examples and embodiments of the invention may be modified or practiced without departing from the principles described.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (4)

1. An oil-free screw compressor temperature control method, comprising:
detecting a plurality of first temperature data by a first temperature sensor disposed at a discharge window of a casing of the oil-free screw compressor and a plurality of second temperature data by a second temperature sensor disposed above the oil-free screw compressor in the casing at a plurality of times of an i-th detection period;
determining first rotation speed data of the oil-free screw compressor in an ith detection period and second rotation speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
Predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
if the radius of the belt pulley needs to be adjusted, predicting third rotating speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotating speed data;
determining a target pulley radius according to the third rotation speed data and the first rotation speed data;
determining a target belt pulley according to the radius of the target belt pulley, and controlling the belt to be switched to the target belt pulley;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection period according to the first temperature data and the second temperature data, including:
fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments;
fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments;
Performing difference on the first temperature function and the second temperature function to obtain a first difference function;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function if the heat rejection capability of the fan is saturated;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function, comprising:
acquiring a first derivative function of the first temperature function;
obtaining a second derivative function of the second temperature function;
obtaining a third derivative function of the first difference function;
if the first, second and third guide functions satisfy the first, second and third conditions C1, C2 and C3 simultaneously, determining that the heat rejection capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈ >For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection cycle based on the first temperature function, the second temperature function, and the first difference function if the heat rejection capability of the fan is saturated, comprising:
determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time;
if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time includes:
according to the formula
，
Determining a predicted temperatureWherein, the method comprises the steps of, wherein,t 1,A for the first target moment of time in question,f 2 as a second temperature function, +.>A second derivative function that is a second temperature function,t i ,m+1 the mth moment of the (i+1) th detection period is the mth moment, and the mth moment is the ending moment of the (i+1) th detection period;
If the radius of the belt pulley needs to be adjusted, predicting third rotation speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotation speed data, wherein the third rotation speed data comprises:
determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan;
determining a volume multiple according to the air volume and the volume of the case;
predicting third rotation speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotation speed data;
predicting third rotation speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotation speed data, wherein the third rotation speed data comprises:
according to the formula
，
Determining the third rotational speed datan 3 Wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
2. An oil-free screw compressor temperature control system, comprising:
The detection module is used for detecting a plurality of first temperature data through a first temperature sensor arranged at an exhaust window of a case of the oil-free screw compressor at a plurality of moments of an ith detection period and detecting a plurality of second temperature data through a second temperature sensor arranged above the oil-free screw compressor in the case;
the rotating speed module is used for determining first rotating speed data of the oil-free screw compressor in an ith detection period and second rotating speed data of a fan arranged at the exhaust window, wherein an engine main shaft of the oil-free screw compressor is connected with a belt pulley arranged on a transmission shaft of the fan through a belt;
the predicted temperature module is used for predicting the predicted temperature above the oil-free screw compressor in the case when the (i+1) th detection period is finished according to the first temperature data and the second temperature data;
the judging module is used for determining whether the radius of a belt pulley on a transmission shaft of the fan needs to be adjusted according to the predicted temperature;
the predicted rotating speed module is used for predicting the third rotating speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotating speed data if the radius of the belt pulley needs to be adjusted;
The radius module is used for determining the radius of the target belt pulley according to the third rotating speed data and the first rotating speed data;
the switching module is used for determining a target belt pulley according to the radius of the target belt pulley and controlling the belt to be switched to the target belt pulley;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection period according to the first temperature data and the second temperature data, including:
fitting the first temperature data detected in the ith detection period with the plurality of moments to obtain a first temperature function between the first temperature data and the plurality of moments;
fitting the second temperature data detected in the ith detection period with the plurality of moments to obtain a second temperature function between the second temperature data and the plurality of moments;
performing difference on the first temperature function and the second temperature function to obtain a first difference function;
determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection period according to the first temperature function, the second temperature function and the first difference function if the heat rejection capability of the fan is saturated;
Determining whether the heat rejection capability of the fan is saturated according to the first temperature function, the second temperature function and the first difference function, comprising:
acquiring a first derivative function of the first temperature function;
obtaining a second derivative function of the second temperature function;
obtaining a third derivative function of the first difference function;
if the first, second and third guide functions satisfy the first, second and third conditions C1, C2 and C3 simultaneously, determining that the heat rejection capacity of the fan is saturated, wherein the first condition C1 isThe second condition C2 is +.>The third condition C3 is，t i,m The mth moment of the ith detection period and the mth moment is the ending moment of the ith detection period, wherein ∈>For the first derivative function, +.>For the second derivative function, +.>Is a third derivative function;
predicting a predicted temperature above the oil-free screw compressor in the chassis at the end of the (i+1) th detection cycle based on the first temperature function, the second temperature function, and the first difference function if the heat rejection capability of the fan is saturated, comprising:
determining a first target moment for enabling the function value of the first difference function to be 0 according to the first difference function;
If the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time;
if the first target time is later than the ending time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function;
if the first target time is earlier than or equal to the end time of the (i+1) th detection period, determining the predicted temperature according to the second temperature function and the first target time includes:
according to the formula
，
Determining a predicted temperatureWherein, the method comprises the steps of, wherein,t 1,A for the first target moment of time in question,f 2 as a second temperature function, +.>A second derivative function that is a second temperature function,t i ,m+1 the mth moment of the (i+1) th detection period is the mth moment, and the mth moment is the ending moment of the (i+1) th detection period;
if the radius of the belt pulley needs to be adjusted, predicting third rotation speed data of the fan in the (i+1) th detection period according to the second temperature data, the predicted temperature and the second rotation speed data, wherein the third rotation speed data comprises:
determining the volume of air flowing through the cross section of the fan in each detection period according to the design parameters of the fan and the second rotating speed data of the fan;
Determining a volume multiple according to the air volume and the volume of the case;
predicting third rotation speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotation speed data;
predicting third rotation speed data of the fan in the (i+1) th detection period according to the volume multiple, the second temperature data, the predicted temperature and the second rotation speed data, wherein the third rotation speed data comprises:
according to the formula
，
Determining the third rotational speed datan 3 Wherein B is the volume multiple,n 2 For the second rotational speed data,T T For a preset temperature threshold above the oil-free screw compressor in the cabinet,for the predicted temperature, T i,2,m Is the second temperature data at the end time of the ith detection period.
3. An oil-free screw compressor temperature control apparatus, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the memory-stored instructions to perform the method of claim 1.
4. A computer readable storage medium, having stored thereon computer program instructions which, when executed by a processor, implement the method of claim 1.
CN202311194633.6A 2023-09-15 2023-09-15 Temperature control method and system for oil-free screw compressor Active CN116928106B (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6082971A (en) * 1998-10-30 2000-07-04 Ingersoll-Rand Company Compressor control system and method
JP2005248864A (en) * 2004-03-04 2005-09-15 Hokuetsu Kogyo Co Ltd Cooling mechanism of engine driving type oil-free compressor
WO2016121385A1 (en) * 2015-01-30 2016-08-04 株式会社デンソー Air conditioning device
CN110475973A (en) * 2017-03-31 2019-11-19 株式会社日立产机系统 Gas compressor
CN114341495A (en) * 2019-10-31 2022-04-12 株式会社日立产机系统 Compressor, monitoring system and monitoring method of compressor
CN115597203A (en) * 2022-07-28 2023-01-13 珠海格力节能环保制冷技术研究中心有限公司（Cn） Control method and control device of air conditioner, processor and air conditioning system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6082971A (en) * 1998-10-30 2000-07-04 Ingersoll-Rand Company Compressor control system and method
JP2005248864A (en) * 2004-03-04 2005-09-15 Hokuetsu Kogyo Co Ltd Cooling mechanism of engine driving type oil-free compressor
WO2016121385A1 (en) * 2015-01-30 2016-08-04 株式会社デンソー Air conditioning device
CN110475973A (en) * 2017-03-31 2019-11-19 株式会社日立产机系统 Gas compressor
CN114341495A (en) * 2019-10-31 2022-04-12 株式会社日立产机系统 Compressor, monitoring system and monitoring method of compressor
CN115597203A (en) * 2022-07-28 2023-01-13 珠海格力节能环保制冷技术研究中心有限公司（Cn） Control method and control device of air conditioner, processor and air conditioning system

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