JP2012206261A - Rotary type fluid transport machine system and method of controlling rotary type fluid transport machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary type fluid transport machine system capable of stably stabilizing a control of a motor of the rotary type transport machine even when the difference between the temperature of a fluid flowing in a part to be supplied and the temperature of the fluid flowing out from the part to be supplied is large and the temperature is remarkably changed in a relatively short time.SOLUTION: The rotary fluid transport machine system 1 is provided with the rotary type fluid transport machine 3 using a motor 4 as a driving source to send the fluid to the part 2 to be supplied and a motor control part 11. In the rotary type fluid transport machine system 1, the difference (fluid temperature difference) of the temperature of the fluid flowing in to the part 2 to be supplied and the temperature of the fluid flowing out from the part 2 to be supplied is periodically changed. The motor control part 11 is provided with a feed back value forming part 13 for forming a feed back value using the maximum value of sampling values extracted from the fluid temperature difference with a fixed interval in one cycle of the cycle of fluctuation of the fluid temperature difference and a feed back control part 15 for controlling the motor 4 on the basis of the target value of the liquid temperature difference and the feed back value.

Description

  The present invention relates to a rotary fluid transport machine system having a rotary fluid transport machine such as a pump. The present invention also relates to a method for controlling a rotary fluid transport machine such as a pump.

  Conventionally, as a resin molding apparatus for manufacturing a resin product, a mold, a supply pipe through which cooling water supplied to the mold passes, a discharge pipe through which cooling water discharged from the mold passes, and a supply pipe There is known a resin molding apparatus provided with a pump for sending cooling water to a mold through a metal plate (for example, see Patent Document 1). The resin molding apparatus described in Patent Literature 1 includes a first temperature sensor that detects the temperature of cooling water that passes through a supply pipe, and a second temperature sensor that detects the temperature of cooling water that passes through a discharge pipe. . In this resin molding apparatus, the discharge flow rate of the pump is controlled based on the difference between the temperature of the cooling water detected by the first temperature sensor and the temperature of the cooling water detected by the second temperature sensor.

  In the molding cycle of a resin product in a resin molding apparatus, generally, an injection process for filling a mold with a resin, a cooling process for cooling the resin filled in the mold, and a mold is opened to take out a molded product. An extraction process is included, and the injection process, the cooling process, and the extraction process are performed in this order. The mold temperature during the molding cycle rises during the injection process, gradually decreases during the cooling process, and further decreases during the removal process. The molding cycle is, for example, about several tens of seconds, but it may be about 2 minutes if it becomes longer.

  Conventionally, a system called a large temperature difference system is known as a system for realizing energy saving. In this large temperature difference system, for example, by increasing the difference between the temperature of the air supplied from the air conditioner to the room and the temperature of the air returning from the room to the air conditioner, the air conditioning is maintained while maintaining the cooling capacity of the room. Energy saving is realized by reducing the power of the blower constituting the apparatus. In other words, the indoor cooling capacity is the difference between the flow rate of air circulating between the air conditioner and the room, and the temperature difference between the temperature of air supplied from the air conditioner to the room and the temperature of air returning from the room to the air conditioner. Because it is expressed as a product (that is, (cooling capacity) = (air flow rate) × (temperature difference)), if the temperature difference is increased, the air flow rate is reduced while maintaining the indoor cooling capacity. be able to. Therefore, in the large temperature difference system, by taking a large temperature difference, for example, the power of the blower is reduced while maintaining the indoor cooling capacity, thereby realizing energy saving. An air conditioning system using a large temperature difference system is disclosed in Patent Document 2, for example.

JP-A-4-122613 JP 2007-322024 A

  If a large temperature difference system is used for the resin molding apparatus described in Patent Document 1, it is possible to realize energy saving of the resin molding apparatus. That is, if the difference between the temperature of the cooling water supplied to the mold and the temperature of the cooling water discharged from the mold is increased, the power of the pump is reduced while maintaining the temperature adjustment capability of the mold, Energy saving can be realized.

  Here, in the case of an air conditioning system, in general, the temperature of the room to which air from the air conditioner is supplied does not fluctuate greatly in a short time, so the temperature of the air supplied to the room and the air returning from the room to the air conditioner The temperature difference from the temperature does not vary greatly in a short time. Therefore, in the case of an air conditioning system, even if feedback control using the temperature difference as a feedback value is performed so that the temperature difference between the temperature of the air supplied to the room and the temperature of the air returning to the air conditioner becomes a predetermined target value. The feedback value does not fluctuate greatly in a short time.

  On the other hand, in the case of the resin molding apparatus described in Patent Document 1, the temperature of the mold to which the cooling water is supplied fluctuates periodically in about several tens of seconds, for example, depending on the molding cycle. Therefore, the temperature difference between the temperature of the cooling water supplied to the mold (supply temperature) and the temperature of the cooling water discharged from the mold (discharge temperature) varies greatly in a short time. Therefore, in the case of the resin molding apparatus described in Patent Document 1, if feedback control is performed using the temperature difference as a feedback value so that the temperature difference between the supply temperature and the discharge temperature becomes a predetermined target value, the feedback value is short. It varies greatly with time.

When the motor that drives the pump is, for example, an AC (alternating current) motor, the rotational speed of the motor is proportional to the frequency of the alternating current power supplied to the motor (motor frequency), and the pump discharge flow rate is also the motor frequency. Is proportional to Therefore, the following relationship is established between the heat exchange amount between the mold and the cooling water, the motor frequency, and the temperature difference between the cooling water supply temperature and the discharge temperature.
Heat exchange amount ∝ motor frequency x temperature difference, ie, temperature difference ∝ heat exchange amount / motor frequency Therefore, when the heat exchange amount is constant, the temperature difference and the motor frequency are inversely proportional, and the motor frequency is high Then, although the fluctuation amount of the temperature difference with respect to the fluctuation amount of the motor frequency is small, the fluctuation amount of the temperature difference with respect to the fluctuation amount of the motor frequency becomes large in the region where the motor frequency is low.

Moreover, in the resin molding apparatus described in Patent Document 1, a pump and a mold are connected by a supply pipe, a discharge pipe, and the like, and there is a distance from the pump to the mold. Therefore, there is a time delay (delay time) until the cooling water discharged from the pump is actually supplied to the mold when the temperature is detected by the first temperature sensor and the second temperature sensor. This delay time is determined by the following equation based on the unit flow rate of the cooling water, the reciprocating distance between the pump and the mold, and the inner diameter of the flow path between the pump and the mold.
Delay time = (inner diameter / 2) ² × π × reciprocating distance / unit flow rate = total flow channel volume / unit flow rate Since the total flow channel volume is constant, the delay time is inversely proportional to the unit flow rate of cooling water. Further, since the unit flow rate of the cooling water is proportional to the motor frequency, the delay time is inversely proportional to the motor frequency. Accordingly, in the region where the motor frequency is high, the variation amount of the delay time with respect to the variation amount of the motor frequency is small, but in the region where the motor frequency is low, the variation amount of the delay time with respect to the variation amount of the motor frequency is large.

  In the large temperature difference system, the motor frequency is lowered to increase the temperature difference between the supply temperature and the discharge temperature. When the motor frequency is lowered, the fluctuation amount of the temperature difference with respect to the fluctuation amount of the motor frequency becomes large. Therefore, when feedback control using the temperature difference between the supply temperature and the discharge temperature as a feedback value is performed, the fluctuation amount of the feedback value increases. . Also, as the motor frequency decreases, the amount of fluctuation in the delay time with respect to the amount of fluctuation in the motor frequency increases, so when feedback control is performed using the temperature difference between the supply temperature and the discharge temperature as a feedback value, the amount of fluctuation in the feedback value is reduced. It gets bigger. That is, when the motor frequency is lowered, the influence of the temperature difference is multiplied by the influence of the delay time, and the fluctuation amount of the feedback value is amplified.

  As described above, if a large temperature difference system is used in the resin molding apparatus described in Patent Document 1, it is possible to realize energy saving of the resin molding apparatus. However, when the large temperature difference system is used in the resin molding apparatus described in Patent Document 1, if the temperature difference between the supply temperature and the discharge temperature is used as a feedback value, the feedback value varies greatly in a short time. In the large temperature difference system, since the motor frequency is low, if the temperature difference between the supply temperature and the discharge temperature is used as a feedback value, the amount of fluctuation in the feedback value increases.

  As described above, when the temperature difference between the supply temperature and the discharge temperature is large and the temperature difference between the supply temperature and the discharge temperature fluctuates greatly in a short time, if the temperature difference is used as a feedback value, the feedback value is short. It fluctuates greatly with time, and the fluctuation amount of the feedback value also increases. For this reason, when the temperature difference between the supply temperature and the discharge temperature is large and changes greatly in a short time, if the temperature difference is set to a feedback value, the motor speed will cause overshoot or hunting, resulting in poor motor control. May become stable. In order to solve this problem, it is generally only necessary to adjust the parameters of the feedback control. However, the optimum parameters differ depending on the mold characteristics and the flow rate of the cooling water. Therefore, the adjustment is performed whenever the conditions change. It is difficult.

  Therefore, the problem of the present invention is that the temperature difference between the inflow temperature of the fluid to the supplied part to which the fluid is supplied and the outflow temperature of the fluid from the supplied part is large and fluctuates greatly in a relatively short time Even so, an object of the present invention is to provide a rotary fluid transport machine system capable of stabilizing control of a motor that is a drive source of the rotary fluid transport machine. Further, the problem of the present invention is that even when the temperature difference between the inflow temperature of the fluid to the supplied part and the outflow temperature of the fluid from the supplied part is large and fluctuates greatly in a relatively short time, It is an object of the present invention to provide a control method for a rotary fluid transport machine that can stabilize the control of a motor that is a drive source of the rotary fluid transport machine.

  In order to solve the above-described problems, a rotary fluid transport machine system according to the present invention uses a motor as a drive source and sends a fluid toward a supplied part to which a fluid is supplied, and to the supplied part. A first temperature sensor that detects the temperature of the fluid that flows in; a second temperature sensor that detects the temperature of the fluid that flows out of the supplied part; and a motor control unit that controls the motor, and is detected by the first temperature sensor. The fluid temperature difference, which is the difference between the fluid temperature detected by the second temperature sensor and the fluid temperature detected by the second temperature sensor, periodically fluctuates at a predetermined cycle, and the motor control unit performs sampling by extracting the fluid temperature difference at regular intervals. A feedback value generation unit that generates a feedback value by using the maximum value within one cycle of the fluctuation cycle of the fluid temperature difference, and controls the number of revolutions of the motor based on the target value and the feedback value of the fluid temperature difference Do Characterized in that it comprises a fed back control unit.

  In the rotary fluid transport machine system of the present invention, the maximum value within one cycle of the fluctuation cycle of the fluid temperature difference is used as the sampling value obtained by extracting the fluid temperature difference that periodically fluctuates in a predetermined cycle at regular intervals. Thus, a feedback value for controlling the rotation speed of the motor is generated. Therefore, even if the fluid temperature difference between the inflow temperature of the fluid to the supplied part and the outflow temperature of the fluid from the supplied part greatly fluctuates in a relatively short time, it is compared with the case where the sampling value is directly used as the feedback value. Thus, it is possible to prevent the feedback value from fluctuating greatly in a short time. Therefore, even if the fluid temperature difference is large, the motor speed is low, and the fluctuation amount of the feedback value is large, overshoot or hunting of the motor speed is suppressed and the motor control is stabilized. It becomes possible. As a result, in the present invention, even when the fluid temperature difference is large and fluctuates greatly in a relatively short time, the motor control can be stabilized.

  In the present invention, the feedback value generation unit stores, for example, a maximum temperature difference maximum value that is a maximum value of sampling values within a predetermined time, and a maximum value update processing unit that updates the maximum temperature difference timely, and a predetermined time A minimum value update processing unit that stores a temperature difference minimum value that is the minimum value of the sampling values and updates the temperature difference minimum value in a timely manner, and an update end determination unit that determines whether the temperature difference maximum value or the temperature difference minimum value has been updated A feedback value update processing unit that stores the feedback value and updates the feedback value in a timely manner.

  In the present invention, the maximum value update processing unit updates the temperature difference maximum value using the sampling value as the temperature difference maximum value when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit. The updated temperature difference maximum value is stored together with the minimum value update processing unit when the sampling value exceeds the maximum temperature difference stored in the maximum value update processing unit and when the sampling value is the minimum value update processing unit. When the temperature difference is less than the stored temperature difference minimum value, the temperature difference minimum value is updated with the sampling value as the temperature difference minimum value, and the updated temperature difference minimum value is stored. The update end determination timer is started at the time of conversion, the sampling value exceeds the maximum temperature difference stored in the maximum value update processing unit, and the sampling value is stored in the minimum value update processing unit When the temperature difference is below the minimum value, the update end determination timer is reset, and when the update end determination timer counts up, it is determined that the update of the temperature difference minimum value has ended, and the update end determination timer is reset. The feedback value update processing unit stores the maximum value in the maximum value update processing unit when the maximum temperature difference exceeds the feedback value stored in the feedback value update processing unit and when the update end determination timer counts up. When the update value is updated and the updated feedback value is stored and the update end determination timer is counted up, the maximum value update processing unit The maximum temperature difference value stored in the initial value is reset to the initial value, and the minimum value update processing unit stores the maximum temperature difference stored in the minimum value update processing unit. It is preferable to reset the value to the initial value. With this configuration, when the update end determination timer is counted up regardless of the conditions of the supplied part, the maximum value and the minimum value of the sampling value in one cycle of the fluid temperature difference fluctuation cycle are specified. In addition, the maximum value of the sampling value in one cycle of the fluid temperature difference fluctuation period is acquired as the temperature difference maximum value, and the feedback value can be updated based on the temperature difference maximum value.

  In the present invention, the feedback value generation unit includes an update determination unit that determines whether or not the feedback value stored in the feedback value update processing unit has been updated within a predetermined time, and the update determination unit performs update determination at the time of initialization. When the timer starts, when the sampling value exceeds the maximum temperature difference stored in the maximum value update processing unit, when the update end determination timer counts up, and when the sampling value exceeds the target value When the update determination timer is reset and the update determination timer counts up, it is determined that the feedback value stored in the feedback value update processing unit has not been updated for a predetermined time, and the update determination timer is reset, The feedback value update processing unit calculates the sampling value when the update determination timer counts up. When the feedback value is updated as the feedback value and the updated feedback value is stored and the update determination timer is counted up, the maximum value update processing unit stores the maximum temperature difference stored in the maximum value update processing unit. Preferably, the minimum value update processing unit resets the minimum temperature difference value stored in the minimum value update processing unit to the initial value, and the update end determination unit resets the update end determination timer. . With this configuration, for example, before the update end determination timer counts up, the sampling value falls below the minimum temperature difference stored in the minimum value update processing unit, and the sampling value gradually decreases periodically. It is possible to update the feedback value even if it goes.

  In the present invention, the maximum value update processing unit, when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, and when the sampling value is stored in the minimum value update processing unit The temperature difference maximum value is updated so that the sampling value becomes the maximum temperature difference value when the value is below the maximum value, and the updated temperature difference maximum value is stored. When the temperature difference is less than the stored temperature difference minimum value, the temperature difference minimum value is updated with the sampling value as the temperature difference minimum value, and the updated temperature difference minimum value is stored. When the sampling value exceeds the maximum temperature difference stored in the maximum value update processing unit and the sampling value is stored in the minimum value update processing unit. When the temperature difference is below the minimum temperature difference, the update end determination timer is reset, and when the update end determination timer counts up, it is determined that the update of the temperature difference maximum value has ended, and the update end determination timer is reset. The feedback value update processing unit stores the maximum value in the maximum value update processing unit when the maximum temperature difference exceeds the feedback value stored in the feedback value update processing unit and when the update end determination timer counts up. When the update value is updated and the updated feedback value is stored and the update end determination timer is counted up, the maximum value update processing unit The temperature difference maximum value stored in the initial value is reset to the initial value, and the minimum value update processing unit stores the temperature difference stored in the minimum value update processing unit. A small value may be reset to the initial value. If comprised in this way, regardless of the conditions of a to-be-supplied part, etc., the maximum value of the sampling value in 1 period of the fluctuation period of fluid temperature difference will be specified, and the maximum value of the sampling value in 1 period of the fluctuation period of fluid temperature difference Can be acquired as the maximum temperature difference value, and the feedback value can be updated based on the maximum temperature difference value.

  In the present invention, the supplied part is, for example, a mold of a resin molding apparatus. In the case of a mold for a resin molding apparatus, the temperature difference between the inflow temperature of the fluid into the mold and the outflow temperature of the fluid from the mold changes greatly in a relatively short time. Even if a large temperature difference system is used for the rotary fluid transport machine system which is a mold of the molding apparatus, the motor control can be stabilized.

  In order to solve the above problems, a control method for a rotary fluid transport machine according to the present invention controls a rotary fluid transport machine that uses a motor as a drive source and sends a fluid toward a supplied portion to which the fluid is supplied. In the method, a sampling value obtained by extracting a fluid temperature difference periodically changing at a predetermined cycle, which is a difference between a temperature of the fluid flowing into the supplied portion and a temperature of the fluid flowing out of the supplied portion at regular intervals The feedback value is generated using the maximum value in one cycle of the fluctuation cycle of the fluid temperature difference, and the rotational speed of the motor is feedback controlled based on the feedback value.

  In the control method of the rotary fluid transport machine according to the present invention, the maximum value within one cycle of the fluctuation cycle of the fluid temperature difference of the sampling value obtained by extracting the fluid temperature difference that periodically fluctuates in a predetermined cycle at regular intervals. Utilizing this, a feedback value is generated. Therefore, even if the fluid temperature difference between the inflow temperature of the fluid to the supplied part and the outflow temperature of the fluid from the supplied part greatly fluctuates in a relatively short time, it is compared with the case where the sampling value is directly used as the feedback value. Thus, it is possible to prevent the feedback value from fluctuating greatly in a short time. Therefore, even if the fluid temperature difference is large, the motor speed is low, and the fluctuation amount of the feedback value is large, overshoot or hunting of the motor speed is suppressed and the motor control is stabilized. Thus, even when the fluid temperature difference is large and fluctuates greatly in a relatively short time, the motor control can be stabilized.

  As described above, according to the present invention, even when the temperature difference between the inflow temperature of the fluid to the supplied part and the outflow temperature of the fluid from the supplied part is large and fluctuates greatly in a relatively short time. It becomes possible to stabilize the control of the motor that is the drive source of the rotary fluid transport machine.

1 is a block diagram showing a schematic configuration of a rotary fluid transport machine system according to an embodiment of the present invention. It is a graph which shows an example of the fluctuation | variation of the sampling value of a fluid temperature difference, a temperature difference maximum value, and a feedback value when a motor is controlled by the control method concerning embodiment of this invention. It is a graph which shows the other example of the fluctuation | variation of the sampling value of a fluid temperature difference, a temperature difference maximum value, and a feedback value when a motor is controlled by the control method concerning embodiment of this invention. It is a graph which shows an example of the fluctuation | variation of the sampling value of the fluid temperature difference when a motor is controlled by the control method concerning a prior art. It is a graph which shows an example of the fluctuation | variation of the sampling value of a motor frequency and a fluid temperature difference when controlling a motor with the control method concerning embodiment of this invention. It is a graph which shows an example of the fluctuation | variation of the sampling value of a motor frequency and fluid temperature difference when controlling a motor with the control method concerning a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of rotary fluid transport machine system)
FIG. 1 is a block diagram showing a schematic configuration of a rotary fluid transportation machine system 1 according to an embodiment of the present invention.

  A rotary fluid transport machine system 1 of this embodiment is a system (mold temperature control system) for adjusting the temperature of a mold 2 of a resin molding apparatus, and includes a pump 3 as a rotary fluid transport machine. . The pump 3 functions to send a temperature adjusting (heating or cooling) fluid (medium) such as cooling water circulating between the mold 2 and the pump 3 toward the mold 2. The pump 3 includes a motor 4 as a drive source. The mold 2 according to this embodiment is a supplied part to which a fluid is supplied.

  The mold 2 and the pump 3 are connected by a feed pipe 5 through which a fluid sent from the pump 3 to the mold 2 passes and a return pipe 6 through which a fluid returning from the mold 2 to the pump 3 passes. The feed pipe 5 is provided with a temperature sensor 7 as a first temperature sensor for detecting the temperature of the fluid flowing into the mold 2, and the return pipe 6 is provided with a first temperature sensor for detecting the temperature of the fluid flowing out of the mold 2. A temperature sensor 8 is installed as a two-temperature sensor. Between the pump 3 and the temperature sensor 8, a cooling device 9 for heating or cooling the fluid returning from the mold 2 to the pump 3 is installed.

  In the resin molding apparatus, molding includes an injection process for filling the mold 2 with a resin, a cooling process for cooling the resin filled in the mold 2, and a removal process for opening the mold 2 and taking out a molded product. The cycle is executed repeatedly. Further, the injection process, the cooling process, and the extraction process are performed in this order, and the temperature of the mold 2 rises in the injection process, gradually decreases in the cooling process, and further decreases in the extraction process. Therefore, the temperature of the mold 2 periodically rises and falls and fluctuates periodically at a constant cycle. Accordingly, the fluid temperature difference between the temperature of the fluid flowing into the mold 2 and the temperature of the fluid flowing out of the mold 2 also periodically rises and falls and fluctuates periodically at a constant cycle. Note that a large temperature difference system is used in the rotary fluid transport machine system 1 of this embodiment, and the fluid temperature difference is large.

  The rotary fluid transport machine system 1 includes a motor control unit 11 that controls the motor 4. The motor control unit 11 is a control circuit for performing feedback control of the motor 4, and includes arithmetic means such as an MPU, storage means such as ROM, RAM, and nonvolatile memory, input / output means such as an I / O port, and the like. It is constituted by. In addition, the motor control unit 11 functionally includes a subtraction unit 12, a feedback value generation unit 13, a subtraction unit 14, and a feedback control unit 15.

  The subtracting unit 12 calculates and outputs a fluid temperature difference that is a difference between the fluid temperature (inflow temperature) detected by the temperature sensor 7 and the fluid temperature (outflow temperature) detected by the temperature sensor 8.

  The feedback value generation unit 13 generates and outputs a feedback value for feedback control of the motor 4 based on the sampling value obtained by extracting the fluid temperature difference output from the subtraction unit 12 at regular intervals. Specifically, the feedback value is generated and output using the maximum value of the sampling value within one cycle of the fluctuation cycle of the fluid temperature difference. The feedback value generation unit 13 includes a maximum value update processing unit 17, a minimum value update processing unit 18, a feedback value update processing unit 19, an update end determination unit 20, and an update determination unit 21.

  The maximum value update processing unit 17 stores the maximum temperature difference value that is the maximum value of the sampling values within a predetermined time and updates the maximum temperature difference value in a timely manner. The minimum value update processing unit 18 stores a temperature difference minimum value that is a minimum value of sampling values within a predetermined time and updates the temperature difference minimum value in a timely manner. The feedback value update processing unit 19 stores the feedback value and updates the feedback value in a timely manner. The update end determination unit 20 determines the end of update of the temperature difference minimum value using the update end determination timer. The update determination unit 21 uses the update determination timer to determine whether or not the feedback value stored in the feedback value update processing unit 19 has been updated within a predetermined time. Detailed functions of each component of the feedback value generation unit 13 will be described in a control method of the motor 4 described later.

  The subtraction unit 14 calculates and outputs a deviation that is a difference between a target value of a temperature difference from a control command unit (not shown) and a feedback value from the feedback value generation unit 13.

  The feedback control unit 15 controls the rotation speed of the motor 4 based on the deviation output from the subtraction unit 14. The motor 4 of this embodiment is an AC motor, and the feedback control unit 15 controls the rotational speed of the motor 4 by adjusting the frequency (motor frequency) of the AC power supplied to the motor 4. Further, the feedback control unit 15 controls the discharge flow rate of the pump 3 (that is, the amount of fluid fed to the mold 2) by controlling the rotation speed of the motor 4. The feedback control unit 15 of this embodiment controls the rotation speed of the motor 4 by PID control that combines proportional control, integral control, and differential control. That is, the feedback control unit 15 calculates a deviation based on the proportional, integral, and differential parameters, converts the deviation into an adjustment amount of the motor frequency, and increases or decreases the motor frequency.

(Motor control method)
FIG. 2 is a graph showing an example of fluctuations in the sampling value ΔT, the temperature difference maximum value ΔTL, and the feedback value Pv when the motor 4 is controlled by the control method according to the embodiment of the present invention. FIG. 3 is a graph showing another example of fluctuations in the sampling value ΔT, the temperature difference maximum value ΔTL, and the feedback value Pv when the motor 4 is controlled by the control method according to the embodiment of the present invention.

The motor 4 of this embodiment is controlled according to the following algorithm.
(1) At initialization, the following initial values are set as the feedback value Pv, the temperature difference maximum value ΔTL, and the temperature difference minimum value ΔTs. At the time of initialization, the update end determination timer Td and the update determination timer Tc set to arbitrary lengths are started.
Feedback value Pv ... "0"
Maximum temperature difference ΔTL ・ ・ ・ “0”
Temperature difference minimum value ΔTs: “Maximum system value”
The feedback value Pv is stored in the feedback value update processing unit 19, the maximum temperature difference value ΔTL is stored in the maximum value update processing unit 17, and the minimum temperature difference value ΔTs is stored in the minimum value update processing unit 18. The The update determination timer Tc is set longer than the update end determination timer Td.

(2) The frequency of the motor 4 is adjusted by PID control so that the feedback value Pv matches the target value Sv of the temperature difference input to the subtracting unit 14.

(3) The feedback value generation unit 13 acquires a sampling value ΔT of the fluid temperature difference. Note that the sampling value ΔT is a sampling value of the absolute value of the fluid temperature difference output from the subtraction unit 12. By using the sampling value ΔT as the sampling value of the absolute value of the fluid temperature difference, it is possible to cope with this algorithm regardless of whether the outflow temperature is higher or lower than the inflow temperature.

(4) When the sampling value ΔT exceeds the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 (that is, when “ΔT> ΔTL”), the maximum value update processing unit 17 sets the sampling value ΔT. Is updated, and the updated temperature difference maximum value ΔTL is stored, and the minimum value update processing unit 18 sets the sampling value ΔT as the temperature difference minimum value ΔTs. The temperature difference minimum value ΔTs is updated and the updated temperature difference minimum value ΔTs is stored. Moreover, the update end determination unit 20 resets the update end determination timer Td, and the update determination unit 21 resets the update determination timer Tc.

(5) When the sampling value ΔT falls below the temperature difference minimum value ΔTs stored in the minimum value update processing unit 18 (that is, when “ΔT <ΔTs”), the minimum value update processing unit 18 The temperature difference minimum value ΔTs is updated with the temperature difference minimum value ΔTs as well as the updated temperature difference minimum value ΔTs is stored, and the update end determination unit 20 resets the update end determination timer Td. When ΔT <ΔTs, the maximum temperature difference value ΔTL is not updated.

(6) When the temperature difference maximum value ΔTL exceeds the feedback value Pv stored in the feedback value update processing unit 19 (that is, when “Pv <ΔTL”), the feedback value update processing unit 19 performs the maximum value update processing. The feedback value Pv is updated with the temperature difference maximum value ΔTL stored in the unit 17 as the feedback value Pv, and the updated feedback value Pv is stored.

(7) When the update end determination timer Td counts up, the feedback value update processing unit 19 updates the feedback value Pv with the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 as the feedback value Pv. The updated feedback value Pv is stored. When the feedback value Pv is updated, the maximum value update processing unit 17 resets the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 to the initial value, and the minimum value update processing unit 18 The temperature difference minimum value ΔTs stored in the value update processing unit 18 is reset to the initial value. Moreover, the update end determination unit 20 resets the update end determination timer Td, and the update determination unit 21 resets the update determination timer Tc.

(8) When the sampling value ΔT is equal to or greater than the target value Sv (that is, when “Sv ≦ ΔT”), the update determination unit 21 resets the update determination timer Tc.

(9) When the update determination timer Tc counts up, the feedback value update processing unit 19 updates the feedback value Pv with the sampling value ΔT at this time as the feedback value Pv and stores the updated feedback value Pv. When the feedback value Pv is updated, the maximum value update processing unit 17 resets the temperature difference maximum value ΔTL to the initial value, and the minimum value update processing unit 18 resets the temperature difference minimum value ΔTs to the initial value. . Moreover, the update end determination unit 20 resets the update end determination timer Td, and the update determination unit 21 resets the update determination timer Tc.

  When the motor 4 is controlled according to the above algorithms (1) to (9), the sampling value ΔT, the temperature difference maximum value ΔTL, and the feedback value Pv are, for example, shown in FIG. It fluctuates as 2. The sampling value ΔT fluctuates as shown by the alternate long and short dash line in FIG. As described above, the fluid temperature difference periodically rises and falls, and periodically fluctuates at a constant period. Therefore, the sampling value ΔT also periodically rises and falls and is constant. It fluctuates periodically at period t.

  As shown in FIG. 2, assuming that each range of elapsed time delimited by a broken line is A1 to A5, B1 to B8, and C1 to C7, the range A1 to A5 has a maximum temperature difference according to the algorithm (4) described above. The value ΔTL is updated. Further, according to the algorithm (6), the feedback value Pv is updated from the beginning in the ranges A1 and A3, and the feedback value Pv is updated from the middle in the range A2. In the ranges A1 to A5, the temperature difference minimum value ΔTs is updated according to the algorithm (4), and the update end determination timer Td and the update determination timer Tc are reset.

  In the range B1 to B8, the temperature difference minimum value ΔTs is updated according to the algorithm (5), and the update end determination timer Td is reset. In the initial stage of ranges B2, B4, and B6, there is a range where ΔT ≧ ΔTs. In this range, temperature difference minimum value ΔTs is not updated, and update end determination timer Td is not reset.

  In the ranges C1 to C7, the maximum temperature difference value ΔTL and the minimum temperature difference value ΔTs are not updated, and the update end determination timer Td continues to be counted. In the ranges C2, C4, C6, and C7, the update end determination timer Td is counted up. Therefore, at the count-up time CP1, the feedback value Pv is updated according to the algorithm (7). Specifically, the feedback value Pv is updated to the maximum value of the sampling value ΔT in the period t before the count-up time point CP1. At the count-up time CP1, the temperature difference maximum value ΔTL and the temperature difference minimum value ΔTs are reset to initial values, and the update end determination timer Td and the update determination timer Tc are reset. Note that, at the count-up time point CP1, the temperature difference maximum value ΔTL instantaneously becomes the initial value “0”, but in FIG. 2, the fluctuation of the temperature difference maximum value ΔTL at the count-up time point CP1 is omitted.

  When the motor 4 is controlled according to the algorithms (1) to (9), the sampling value ΔT, the temperature difference maximum value ΔTL, and the feedback value Pv are, for example, shown in FIG. It may be fluctuated as 3. As shown in FIG. 3, if each range of elapsed time delimited by a broken line is A7 to A9, B10 to B16, and C9 to C14, the temperature difference in the range A7 to A9 is similar to the above-described range A1 to A5. The maximum value ΔTL and the temperature difference minimum value ΔTs are updated, the feedback value Pv is updated, and the update end determination timer Td and the update determination timer Tc are reset.

  In the range B10 to B16, the temperature difference minimum value ΔTs is updated and the update end determination timer Td is reset, as in the above-described ranges B1 to B8. In the ranges C9 to C14, as in the above ranges C1 to C7, the temperature difference maximum value ΔTL and the temperature difference minimum value ΔTs are not updated, and the count of the update end determination timer Td continues. In the initial stage of the range B11, there is a range where ΔT ≧ ΔTs. In this range, the temperature difference minimum value ΔTs is not updated, and the update end determination timer Td is not reset. Further, in the ranges B12 and B13, ΔT ≧ ΔTs except for the end thereof, and in the range excluding the end, the temperature difference minimum value ΔTs is not updated, and the update end determination timer Td is not reset.

  From the algorithms (4), (7), and (8), the update determination timer Tc is reset when “ΔT> ΔTL”, when the update end determination timer Td is counted up, and “Sv ≦ ΔT ”, when these conditions are not satisfied and the update determination timer Tc is counted up, the feedback value Pv is updated according to the algorithm (9) at the count-up time point CP2, The maximum temperature difference value ΔTL and the minimum temperature difference value ΔTs are reset to initial values, and the update end determination timer Td and the update determination timer Tc are reset. Note that, at the count-up time point CP2, the temperature difference maximum value ΔTL instantaneously becomes the initial value “0”, but in FIG. 3, the fluctuation of the temperature difference maximum value ΔTL at the count-up time point CP2 is omitted.

(Main effects of this form)
As described above, in this embodiment, when the update end determination timer Td counts up, the feedback value Pv is updated using the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 as the feedback value Pv. That is, in this embodiment, when the update end determination timer Td counts up, the feedback value Pv is updated using the maximum value of the sampling value ΔT within one cycle t as shown in FIG. In this embodiment, when Pv <ΔTL, the feedback value Pv is updated with the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 as the feedback value Pv.

  Therefore, even if the fluid temperature difference greatly fluctuates in a relatively short period t, it is possible to prevent the feedback value Pv from fluctuating greatly in a short time compared to the case where the sampling value ΔT is directly used as the feedback value Pv. It becomes possible. Therefore, by using the large temperature difference system, even if the fluid temperature difference increases, the rotational speed of the motor 4 decreases, and the fluctuation amount of the feedback value Pv increases, overshoot or hunting of the rotational speed of the motor 4 increases. It is possible to stabilize the control of the motor 4 by suppressing the occurrence of the above. As a result, in this embodiment, even when the fluid temperature difference is large and fluctuates greatly in a relatively short time, the control of the motor 4 can be stabilized.

  In this embodiment, when Pv <ΔTL, the feedback value Pv is updated with the temperature difference maximum value ΔTL stored in the maximum value update processing unit 17 as the feedback value Pv. For example, the target value Sv is changed. For example, the feedback value Pv can be quickly updated even when the maximum temperature difference ΔTL increases rapidly.

  In this embodiment, the motor 4 is controlled according to algorithms (4) to (7). Therefore, in this embodiment, the maximum value and the minimum value of the sampling value ΔT in the cycle t are specified when the update end determination timer Td is counted up regardless of the conditions of the mold 2 and the molding conditions. The maximum value of the sampling value ΔT in the period t can be acquired as the temperature difference maximum value ΔTL, and the feedback value Pv can be updated based on the temperature difference maximum value ΔTL.

  In this embodiment, the motor 4 is controlled according to algorithms (4) and (7) to (9). Therefore, as shown in FIG. 3, before the update end determination timer Td counts up, the sampling value ΔT falls below the temperature difference minimum value ΔTs stored in the minimum value update processing unit 18 (that is, the sampling value ΔT decreases). The feedback value Pv can be updated even when the sampling value ΔT gradually decreases periodically.

  Further, in this embodiment, as shown in the ranges C1, C3, and C5 in FIG. 2, when ΔT> ΔTs in a short time after ΔT> ΔTs, the update end determination timer Td is not counted up. Therefore, the minimum value of the sampling value ΔT in one cycle t (that is, the bottom of the sampling value ΔT in one cycle t) can be detected appropriately.

  When the sampling value ΔT is used as the feedback value Pv, the average value of the sampling values ΔT approaches the target value Sv. Further, when the sampling value ΔT is used as the feedback value Pv, if the target value Sv is increased in order to introduce the large temperature difference system, the fluctuation amount of the sampling value ΔT is expanded. Hereinafter, a specific example will be described with reference to FIG.

  FIG. 4 shows PID control of the motor 4 using the sampling value ΔT as the feedback value Pv under the initial condition set so that the average value of the sampling value ΔT when the frequency of the motor 4 is 60 Hz is 2 ° C. It is a graph which shows the simulation result at the time. In this simulation, the target value Sv is changed to 6 ° C. at the switching time TP1 while the motor 4 is being driven with the target value Sv being 3 ° C. In this simulation, the influence of the delay time is excluded.

  As shown in FIG. 4, when the motor 4 is subjected to PID control using the sampling value ΔT as the feedback value Pv, the average value of the sampling values ΔT approaches the target value Sv. Further, as shown in FIG. 4, the maximum value of the sampling value ΔT when the target value Sv is 3 ° C. is 4.5 ° C., and the deviation from the target value Sv is 1.5 ° C., but the target value The maximum value of the sampling value ΔT when Sv is 6 ° C. is 8.4 ° C., and the deviation from the target value Sv increases to 2.4 ° C. Thus, when the sampling value ΔT is set to the feedback value Pv, the average value of the sampling values ΔT approaches the target value Sv. Further, when the sampling value ΔT is set to the feedback value Pv and the target value Sv is increased, the amount of fluctuation of the sampling value ΔT is increased. Therefore, if the sampling value ΔT is set as the feedback value Pv and the target value Sv is increased, the maximum value of the sampling value ΔT may exceed the allowable range and affect the molding quality of the resin product.

  On the other hand, in the present embodiment, the temperature difference maximum value ΔTL is used as the feedback value Pv, and therefore the average value of the temperature difference maximum values ΔTL having a smaller fluctuation amount than the sampling value ΔT approaches the target value Sv. Therefore, in this embodiment, even if the target value Sv is increased, the maximum value of the sampling value ΔT can be kept within an allowable range, and the molding quality of the resin product can be ensured.

  Further, when the sampling value ΔT is set to the feedback value Pv, when the target value Sv is switched, as shown in FIG. 6, the fluctuation of the frequency of the motor 4 (motor frequency) increases. Since the maximum value ΔTL is used as the feedback value Pv, even if the target value Sv is switched, as shown in FIG. 5, the fluctuation of the motor frequency can be reduced. 5 and 6, the motor 4 is driven with the target value Sv set to 5 ° C. under the initial condition set so that the average value of the sampling values ΔT when the motor frequency is 60 Hz is 3 ° C. In the meantime, the simulation result when the target value Sv is changed to 7 ° C. at the switching time TP2 is shown, and FIG. 5 shows the simulation result when the temperature difference maximum value ΔTL is set to the feedback value Pv. FIG. 6 shows a simulation result when the sampling value ΔT is the feedback value Pv.

(Other embodiments)
In the embodiment described above, the minimum value of the sampling value ΔT in one cycle t is detected using the update end determination timer Td, but the maximum of the sampling value ΔT in one cycle t is detected using the update end determination timer Td. The value may be detected. In this case, the following algorithms (4 ′) and (5 ′) may be used instead of the above algorithms (4) and (5).
(4 ′) When ΔT> ΔTL, the temperature difference maximum value ΔTL is updated with the sampling value ΔT as the temperature difference maximum value ΔTL, and the updated temperature difference maximum value ΔTL is stored, and the update end determination timer Td and The update determination timer Tc is reset.
(5 ′) When ΔT <ΔTs, the temperature difference maximum value ΔTL is updated so that the sampling value ΔT becomes the temperature difference maximum value ΔTL, the updated temperature difference maximum value ΔTL is stored, and the sampling value ΔT is stored as the temperature difference. The temperature difference minimum value ΔTs is updated as the minimum value ΔTs, the updated temperature difference minimum value ΔTs is stored, and the update end determination timer Td is reset.

  In the embodiment described above, the feedback value Pv is updated when Pv <ΔTL. However, the feedback value Pv does not have to be updated when Pv <ΔTL. In the above-described form, the update determination timer Tc is started at initialization. However, the update determination timer Tc may be started when Sv> ΔT.

  In the embodiment described above, the feedback control unit 15 controls the rotation speed of the motor 4 by PID control that combines proportional control, integral control, and differential control. However, the feedback control unit 15 performs proportional control, integral control, The rotational speed of the motor 4 may be controlled by PI control combined with the above, or the rotational speed of the motor 4 may be controlled by PD control combined with proportional control and differential control. Further, the feedback control unit 15 may control the rotation speed of the motor 4 by other feedback control.

  In the embodiment described above, the rotary fluid transport machine system 1 includes the pump 3 as a rotary fluid transport machine. However, the rotary fluid transport machine system 1 includes a blower (fan) or a rotary fluid transport machine. A compressor (compressor) may be provided. In the embodiment described above, the rotary fluid transport machine system 1 is a mold temperature control system. However, the rotary fluid transport machine system 1 may be a system other than the mold temperature control system.

1 Rotating fluid transport machine system 2 Mold (supplied part)
3 Pump (rotary fluid transport machine)
4 Motor 7 Temperature sensor (first temperature sensor)
8 Temperature sensor (second temperature sensor)
DESCRIPTION OF SYMBOLS 11 Motor control part 13 Feedback value generation part 15 Feedback control part 17 Maximum value update process part 18 Minimum value update process part 19 Feedback value update process part 20 Update end determination part 21 Update determination part Pv Feedback value Tc Update determination timer Td Update end Judgment timer Sv Target value ΔT Sampling value ΔTL Maximum temperature difference ΔTs Minimum temperature difference t Period

Claims (7)

A rotary fluid transport machine that uses a motor as a drive source to send fluid toward a supplied part to which fluid is supplied, a first temperature sensor that detects the temperature of the fluid flowing into the supplied part, and the supplied part A second temperature sensor for detecting the temperature of the fluid flowing out of the motor, and a motor control unit for controlling the motor,
The fluid temperature difference, which is the difference between the fluid temperature detected by the first temperature sensor and the fluid temperature detected by the second temperature sensor, periodically fluctuates at a predetermined period,
The motor control unit generates a feedback value by using a maximum value within one cycle of a fluctuation cycle of the fluid temperature difference of sampling values obtained by extracting the fluid temperature difference at regular intervals; and A rotary fluid transport machine system comprising: a feedback control unit that controls the number of revolutions of the motor based on the target value of the fluid temperature difference and the feedback value.   The feedback value generation unit stores a maximum temperature difference value that is a maximum value of the sampling value within a predetermined time and a maximum value update processing unit that updates the temperature difference maximum value in a timely manner, and the sampling value within a predetermined time A minimum value update processing unit that stores a temperature difference minimum value that is a minimum value of the temperature difference and updates the temperature difference minimum value in a timely manner, and an update end determination unit that determines whether the temperature difference maximum value or the temperature difference minimum value has been updated. The rotary fluid transport machine system according to claim 1, further comprising: a feedback value update processing unit that stores the feedback value and updates the feedback value in a timely manner. The maximum value update processing unit, when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, the sampling value of the temperature difference maximum value as the temperature difference maximum value Update and store the updated temperature difference maximum value,
The minimum value update processing unit is configured such that when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, and the temperature at which the sampling value is stored in the minimum value update processing unit. When the temperature difference is below the minimum difference value, the temperature difference minimum value is updated with the sampling value as the temperature difference minimum value, and the updated temperature difference minimum value is stored,
The update end determination unit starts an update end determination timer at initialization, and when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, and the sampling value The update end determination timer is reset when the temperature difference minimum value stored in the minimum value update processing unit falls below, and the temperature difference minimum value is updated when the update end determination timer counts up. It is determined that it has ended, the update end determination timer is reset,
The feedback value update processing unit updates the maximum value when the maximum temperature difference value exceeds the feedback value stored in the feedback value update processing unit and when the update end determination timer counts up. Update the feedback value with the temperature difference maximum value stored in the processing unit as the feedback value and store the updated feedback value,
When the update end determination timer is counted up, the maximum value update processing unit resets the temperature difference maximum value stored in the maximum value update processing unit to an initial value, and the minimum value update processing unit The rotary fluid transport machine system according to claim 2, wherein the minimum temperature difference value stored in the minimum value update processing unit is reset to an initial value. The feedback value generation unit includes an update determination unit that determines whether or not the feedback value stored in the feedback value update processing unit is updated within a predetermined time,
The update determination unit starts an update determination timer at initialization, and when the sampling value exceeds the maximum temperature difference stored in the maximum value update processing unit, the update end determination timer counts up When the sampling value becomes equal to or greater than the target value, the update determination timer is reset, and when the update determination timer is counted up, the feedback value stored in the feedback value update processing unit Determining that the value has not been updated for a predetermined time, resetting the update determination timer,
The feedback value update processing unit updates the feedback value with the sampling value as the feedback value and stores the updated feedback value when the update determination timer counts up,
When the update determination timer is counted up, the maximum value update processing unit resets the temperature difference maximum value stored in the maximum value update processing unit to an initial value, and the minimum value update processing unit The rotary fluid transport according to claim 3, wherein the temperature difference minimum value stored in the minimum value update processing unit is reset to an initial value, and the update end determination unit resets the update end determination timer. Mechanical system. The maximum value update processing unit, when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, and the temperature at which the sampling value is stored in the minimum value update processing unit When the difference is less than the minimum value, the temperature difference maximum value is updated with the sampling value as the temperature difference maximum value, and the updated temperature difference maximum value is stored,
The minimum value update processing unit, when the sampling value falls below the temperature difference minimum value stored in the minimum value update processing unit, the temperature difference minimum value of the temperature difference minimum value as the sampling value minimum value Update and store the updated temperature difference minimum value,
The update end determination unit starts an update end determination timer at initialization, and when the sampling value exceeds the temperature difference maximum value stored in the maximum value update processing unit, and the sampling value The update end determination timer is reset when the temperature difference minimum value stored in the minimum value update processing unit falls below, and the temperature difference maximum value is updated when the update end determination timer counts up. It is determined that it has ended, the update end determination timer is reset,
The feedback value update processing unit updates the maximum value when the maximum temperature difference value exceeds the feedback value stored in the feedback value update processing unit and when the update end determination timer counts up. Update the feedback value with the temperature difference maximum value stored in the processing unit as the feedback value and store the updated feedback value,
When the update end determination timer is counted up, the maximum value update processing unit resets the temperature difference maximum value stored in the maximum value update processing unit to an initial value, and the minimum value update processing unit The rotary fluid transport machine system according to claim 2, wherein the minimum temperature difference value stored in the minimum value update processing unit is reset to an initial value.   The rotary fluid transportation machine system according to claim 1, wherein the supplied part is a mold of a resin molding apparatus. In a control method of a rotary fluid transport machine that uses a motor as a drive source and sends a fluid toward a supplied portion to which a fluid is supplied.
The difference between the temperature of the fluid flowing into the supplied portion and the temperature of the fluid flowing out of the supplied portion, which is a sampling value obtained by extracting a fluid temperature difference that periodically fluctuates at a predetermined cycle at regular intervals. A rotary fluid transport machine that generates a feedback value using a maximum value within one cycle of the fluctuation cycle of the fluid temperature difference and feedback-controls the rotational speed of the motor based on the feedback value. Control method.

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