Ventilation device and control method for ventilation device

Abstract

This ventilation device comprises: a supply air duct (31) having a plurality of individually openable and closable branch ducts (31-1, 31-2); an air supply blower (22) for supplying air to the supply air duct (31); a supply air pressure sensor (25) for detecting static pressure in the supply air duct (31); and a control device (24) for controlling the air volume of the air supply blower (22) so that the detected value of the air supply pressure sensor (25) becomes a target value. The control device (24): calculates an air volume change amount through multiplication of the difference between the target value and the detected value by a control gain; periodically changes an air volume command value for the air supply blower (22) by using the calculated air volume change amount; and updates the control gain by using the air volume change amount of the air supply blower (22) and the amount of change in the detected value obtained as a result of a change in air volume according to the air volume change amount of the air supply blower (22), and uses the updated control gain to calculate the air volume change amount of the air supply blower (22) for the next cycle.

Description

Ventilation device and method for controlling ventilation device

[0001] The present disclosure relates to a ventilation device and a method for controlling a ventilation device.

[0002] Conventionally, in air conditioners operated with a constant air volume air conditioning system, a method has been known in which a pressure sensor that detects static pressure is installed in the air supply duct, and an inverter device is used to frequency-control the fan rotation speed so that the detection signal from the pressure sensor remains constant (see, for example, Patent Document 1).

[0003] Patent No. 3370449

[0004] However, the constant air volume control of the blower disclosed in Patent Document 1 has the problem that it is not possible to achieve a stable and rapid response to changes in static pressure, as will be described later.

[0005] The present disclosure has been made in view of the above, and aims to provide a ventilation device that can respond stably and quickly to changes in static pressure.

[0006] To solve the above-mentioned problems and achieve the object, the present disclosure provides a ventilation device including an air supply duct having a plurality of branch ducts that can be opened and closed individually, an air supply fan that supplies air to the air supply duct, an air supply pressure sensor that detects the static pressure of the air supply duct, and a control device that controls the airflow of the air supply fan so that a first detection value of the air supply pressure sensor becomes a first target value. The control device calculates an airflow change amount by multiplying a difference between the first target value and the first detection value by a first control gain, periodically changes an airflow command value for the air supply fan using the calculated airflow change amount, and updates the first control gain using the airflow change amount of the air supply fan and a change in the first detection value obtained by the change in airflow due to the airflow change amount of the air supply fan, and uses the first control gain to calculate the airflow change amount of the air supply fan for the next cycle.

[0007] The ventilation device of the present disclosure has the advantage of being able to respond stably and quickly to changes in static pressure.

[0008] FIG. 1 is a diagram showing a first state of a ventilation device for explaining a comparative example; FIG. 2 is a diagram showing a second state of a ventilation device for explaining a comparative example; FIG. 3 is a diagram showing a third state of a ventilation device for explaining a comparative example; FIG. 4 is a control block diagram showing the control configuration of a control device for a ventilation device for explaining a comparative example; FIG. 5 is a diagram showing the relationship between static pressure and air volume when the ventilation device is in the first state, second state, and third state for explaining a comparative example; FIG. 1 is a diagram showing input / output specifications of a blower of a ventilation device. FIG. 2 is a diagram showing output specifications of an air supply pressure sensor of a ventilation device according to a first embodiment. FIG. 3 is a diagram for explaining a result of determining a first air volume step increase / decrease value performed by a control device of a ventilation device according to a first embodiment. FIG. 4 is a diagram for explaining a result of determining a second air volume step increase / decrease value performed by a control device of a ventilation device according to a first embodiment.

[0009] A ventilation device and a control method for the ventilation device according to an embodiment will be described in detail below with reference to the drawings.

[0010] Before describing the embodiment, the stability issue in a comparative example will be described. Fig. 1 is a diagram showing a first state of a ventilation device for explaining the comparative example. Fig. 2 is a diagram showing a second state of the ventilation device for explaining the comparative example. Fig. 3 is a diagram showing a third state of the ventilation device for explaining the comparative example. In Figs. 1 to 3, the ventilation device includes a ventilation device main body 1, an intake air blower 2, a control device 4, an intake air pressure sensor 5, a collecting duct 12, branch ducts 13-1, 13-2, and 13-3, and switches 14-1, 14-2, and 14-3.

[0011] A supply air blower 2 that supplies air into a room is disposed in the ventilation device main body 1. A collecting duct 12 is connected immediately after the supply air output of the ventilation device main body 1. Branch ducts 13-1, 13-2, and 13-3 branch off from the collecting duct 12 and supply air to each room. Switches 14-1, 14-2, and 14-3 are provided on the branch ducts 13-1, 13-2, and 13-3, respectively, and individually open and close the air passages of each branch duct 13-1, 13-2, and 13-3. A supply air pressure sensor 5 is installed in the duct immediately after the supply air output of the ventilation device main body 1 and detects the static pressure of the duct. A control device 4 adjusts the output of the supply air blower 2 based on the target air volume, target static pressure, and the value detected by the supply air pressure sensor 5.

[0012] 1, the switch 14-1 is closed and does not supply air, and the switches 14-2 and 14-3 are open and supply air. ３ / h, the output of the supply air blower 2 is controlled to 60% so that the static pressure in the collecting duct 12 becomes 100 Pa, which is the target static pressure P*. ３ / h, and the air volumes of the branch ducts 13-2 and 13-3 are 300 m ３ It is assumed that the engine is operating stably at 1000kJ / h.

[0013] In the second state shown in Figure 2, the switch 14-1 is open and switched to the air supply state. At this time, the air supply volume of the ventilation system is 750 m ３ / h, and the air volumes of the branch ducts 13-1, 13-2, and 13-3 are 250 m ３The static pressure in the collecting duct 12 also decreases, and is assumed to have decreased to 80 Pa in FIG.

[0014] In the third state shown in Figure 3, the output of the supply air blower 2 is increasing. The control device 4 detects a decrease in the static pressure of the collecting duct 12 using the supply air pressure sensor 5, and increases the output of the supply air blower 2 to 80% so that the target static pressure P* becomes 100 Pa. As a result, the supply air volume becomes 900 m ３ As a result, the static pressure of the collecting duct 12 becomes 100 Pa, and the air volumes of the branch ducts 13-1, 13-2, and 13-3 are each 300 m ３ / h, and the desired air volume can be obtained.

[0015] 4 is a diagram illustrating the relationship between static pressure and air volume when the ventilation device is in the first, second, and third states for explaining a comparative example. The horizontal axis represents air volume, and the vertical axis represents static pressure. Point d1 represents the first state shown in FIG. 1, point d2 represents the second state shown in FIG. 2, and point d3 represents the third state shown in FIG. 3.

[0016] FIG. 5 is a control block diagram showing the control configuration of the control device 4 of a ventilation device to explain a comparative example. In FIG. 5, a subtractor 15 calculates a difference ΔP between the target static pressure P* and the detected static pressure Px detected by the supply air pressure sensor 5. A multiplier 16 multiplies the difference ΔP by a gain G and converts the difference ΔP into an airflow command value Qcont. An upper / lower limiter 17 applies a limit if the airflow command value Qcont, which is the output of the multiplier 16, deviates from a certain range. The airflow command value Qcont is output from the upper / lower limiter 17. Through this series of operations, the airflow command value Qcont, which is the airflow output, is controlled so that the detected static pressure Px matches the target static pressure P*.

[0017] 6 is a diagram illustrating the relationship between static pressure and air volume when the ventilation device is in a first, second, third, fourth, and fifth states, for explaining a comparative example. The fourth state is indicated by point d4, and the fifth state is indicated by point d5. In the fourth and fifth states, one of the three switches 14-1, 14-2, and 14-3 is open and two are closed.

[0018] When the state changes from the first state (point d1) in which one switch is closed and two switches are open as shown in FIG. 1 to the third state (point d3) in which all three switches are open as shown in FIG. 3, the state passes through the second state (point d2) in which the static pressure shown in FIG. 2 decreases, as indicated by arrow A1.

[0019] On the other hand, when the state changes from the first state (point d1) where one switch is closed and two switches are open to the fifth state (point d5) where one switch is open and two switches are closed, the state passes through the fourth state (point d4) where the static pressure increases, as shown by arrow A2. The amount of decrease in static pressure from the first state (point d1) to the second state (point d2) is equal to the amount of increase in static pressure from the first state (point d1) to the fourth state (point d4).

[0020] However, when focusing on the change in air volume, the increase in air volume from the second state (point d2) to the third state (point d3) indicated by arrow B1 is greater than the decrease in air volume from the fourth state (point d4) to the fifth state (point d5) indicated by arrow B2. Thus, even if the change in static pressure due to the opening and closing of branch ducts 13-1, 13-2, and 13-3 is the same, a large increase in air volume is required when the static pressure decreases, whereas a small decrease in air volume is sufficient when the static pressure increases.

[0021] That is, if air volume control is performed with the same gain amount (same motor output amount) for the range of change in static pressure when increasing air volume and when decreasing air volume, stable control cannot be achieved.

[0022] 7 is a diagram showing the open / closed states of switches 14-1, 14-2, and 14-3 and the temporal change in static pressure in collecting duct 12 when static pressure drops in a comparative example. When switch 14-1 opens at time t1, the static pressure in collecting duct 12 drops, so control device 4 operates to increase the air volume output of supply air blower 2. However, if air volume control is always performed with the same gain amount (same motor output amount) relative to the range of change in static pressure, the control gain is small and the air volume is likely to be insufficient, and it takes a long time for the static pressure in collecting duct 12 to reach target static pressure P*.

[0023] 8 is a diagram showing the other open / close states of switches 14-1, 14-2, and 14-3 and the temporal change in static pressure in collecting duct 12 when static pressure drops in a comparative example. When switch 14-3 is closed at time t1, the static pressure in collecting duct 12 increases, and control device 4 operates to reduce the airflow output of supply air blower 2. However, if airflow control is always performed using the same gain amount (same motor output amount) relative to the range of change in static pressure, the control gain is large and the airflow is likely to be excessive. As a result, the static pressure in collecting duct 12 exceeds target static pressure P*, causing output to oscillate before reaching target static pressure P*, resulting in a longer time to reach a stable state.

[0024] As described above, in the comparative example, the air volume is always controlled with the same gain amount relative to the range of change in static pressure, which causes problems in terms of stability and speed of control.

[0025] 9 is a conceptual diagram showing the configuration of a ventilation device according to embodiment 1. The ventilation device includes a ventilation device main body 21, an intake air blower 22, an exhaust air blower 23, a control device 24, an intake air pressure sensor 25, an outside air duct 30, an intake air duct 31, an exhaust air duct 32, and a return air duct 33. The outside air duct 30 and the intake air duct 31 form an intake air passage 34, and the return air duct 33 and the exhaust air duct 32 form an exhaust air passage 35.

[0026] The intake air blower 22 is disposed inside the ventilation device main body 21 in the intake air duct 34. By operating the intake air blower 22, outdoor air is supplied into the room. The exhaust air blower 23 is disposed inside the ventilation device main body 21 in the exhaust air duct 35. By operating the exhaust air blower 23, indoor air is exhausted to the outside.

[0027] The supply air duct 31 has a collecting duct 38 and branch ducts 31-1 and 31-2. The supply air duct 31 branches into branch duct 31-1 and branch duct 31-2 via the collecting duct 38 and leads to an indoor air outlet (not shown). The supply air pressure sensor 25 is disposed inside the collecting duct 38. In the first embodiment, there are two branch ducts 31-1 and 31-2, but the number of branch ducts is not limited.

[0028] FIG. 10 is a block diagram showing the configuration of the control device 24 of the ventilation apparatus according to the first embodiment. The control device 24 includes a control program 40, a storage unit 41, a blower driver 42, and a sensor input unit 43. The control program 40 includes an air volume calculation unit 40A and a storage control unit 40B. The storage unit 41 is a nonvolatile memory and stores data that needs to be retained and managed when executing the control according to the first embodiment. Specifically, the storage unit 41 stores the target voltage V*, the step increase / decrease determination initial threshold K1, the step increase / decrease upper and lower limits ΔQsup and ΔQinf, and the air volume change period Ti. The supply air blower 22 and the exhaust air blower 23 are connected to the blower driver 42. The supply air pressure sensor 25 is connected to the sensor input unit 43.

[0029] Fig. 11 is a diagram showing input / output specifications of the blowers of the ventilation system according to the first embodiment. The input / output specifications shown in Fig. 11 correspond to the input / output specifications of the intake air blower 22 and the exhaust air blower 23. The blower output (Fout) of the blowers changes in response to an air volume step (Qstep), which is an air volume command value input from the blower driver 42 of the control device 24. In the first embodiment, the specifications of the blowers constituting the ventilation system are the same for both the intake air blower 22 and the exhaust air blower 23, and the output level relative to the rated air volume can be specified in a total of 20 stages from 5% to 100%, but this is not limited to this.

[0030] Fig. 12 is a diagram showing the output specifications of supply pressure sensor 25 of the ventilation system according to embodiment 1. As shown in Fig. 12, supply pressure sensor 25 is designed to output a voltage proportional to the detected static pressure value [Pa], and in embodiment 1, for example, a sensor that outputs 5 [V] when detecting 500 [Pa] is assumed. Note that supply pressure sensor 25 may employ other methods.

[0031] FIG. 13 is a diagram illustrating the results of the determination of the first airflow step increase / decrease value ΔQstep performed by the control device 24 of the ventilation apparatus according to the first embodiment. FIG. 14 is a diagram illustrating the results of the determination of the second airflow step increase / decrease value ΔQstep performed by the control device 24 of the ventilation apparatus according to the first embodiment. In FIGS. 13 and 14 , the horizontal axis represents the difference ΔV1 between the target voltage V* corresponding to the target static pressure and the detected voltage V. The vertical axis represents the airflow step increase / decrease value ΔQstep. The target voltage V* corresponds to the first target value, and the detected voltage V corresponds to the first detected value. The airflow step increase / decrease value ΔQstep corresponds to the airflow change amount. In FIGS. 13 and 14 , the solid background and various patterns distinguish the range of −3 to +3, which represents the increase / decrease value of the airflow step Qstep, which is the airflow command value.

[0032] In FIG. 13 , the thick solid line indicates the first determination result. In FIG. 14 , the thick solid line indicates the second determination result. FIG. 13 shows an initial step increase / decrease determination threshold K1, which is the first step increase / decrease determination threshold for the step increase / decrease determination threshold K. The initial step increase / decrease determination threshold K1 is stored in the memory unit 41. FIG. 14 shows a second step increase / decrease determination threshold K2 for the step increase / decrease determination threshold K. As will be described later, the step increase / decrease determination threshold K is updated in advance each time the air volume step increase / decrease value ΔQstep is calculated. In other words, the step increase / decrease determination threshold K is updated when the air volume step increase / decrease value ΔQstep is calculated, and the updated step increase / decrease determination threshold K is used when calculating the air volume step increase / decrease value ΔQstep for the next cycle. The air volume step increase / decrease value ΔQstep is calculated periodically at intervals that correspond to the air volume change cycle Ti stored in the memory unit 41. The air volume step increase / decrease value ΔQstep is determined using the step increase / decrease determination threshold K as a boundary.

[0033] FIG. 15 is a flowchart showing the operation of the control device 24 of the ventilation device according to the first embodiment. First, the control device 24 determines whether the control timer is equal to or greater than the airflow rate change period Ti (step S001). If the determination in step S001 is No, the process returns and the determination in step S001 is performed. If the determination in step S001 is Yes, the control device 24 clears the control timer (step S002). Here, the control timer is fixed to a count value of 0 while the ventilation device is stopped and counts up while the ventilation device is operating, but this is not limited thereto. For example, when a signal to start operation is input from a remote control (not shown) connected to the ventilation device, the process may proceed to the flowchart shown in FIG. 15 and the control timer may count up accordingly.

[0034] Next, the control device 24 updates the detected voltage V corresponding to the static pressure detected by the intake pressure sensor 25 (step S003). The detected voltage V indicates a voltage value detected by the sensor input unit 43 of the control device 24, and corresponds to the static pressure value of the collecting duct 38. For example, the detected voltage V is updated by acquiring 30 sets of data every two seconds (a total of one minute) and averaging the data, but other methods may also be used.

[0035] Next, the control device 24 calculates the difference between the target voltage V* corresponding to the target static pressure and the detected voltage V (step S004). Next, the control device 24 determines the number of airflow volume change determinations (step S005). If the number of airflow volume change determinations is the first (step S005: Yes), the control device 24 acquires the step increase / decrease determination initial threshold K1 from the storage unit 41 (step S006) and updates the airflow volume step increase / decrease value ΔQstep using the step increase / decrease determination initial threshold K1 (step S008). If the number of airflow volume change determinations is the second or subsequent (step S005: No), the control device 24 updates the step increase / decrease determination threshold K (step S007) and then updates the airflow volume step increase / decrease value ΔQstep using the updated step increase / decrease determination threshold K (step S008). The method for updating the step increase / decrease determination threshold K and the method for updating the airflow volume step increase / decrease value ΔQstep will be described later. Next, the control device 24 updates the air volume step Qstep using the updated air volume step increase / decrease value ΔQstep (step S009).

[0036] Fig. 16 is a control block diagram showing the operation of updating the air volume step Qstep of the control device 24 of the ventilation device according to embodiment 1. Fig. 17 is a control block diagram showing the operation of updating the step increase / decrease determination threshold K of the control device 24 of the ventilation device according to embodiment 1. The flowchart shown in Fig. 15 will be supplemented with an explanation using Figs. 16 and 17.

[0037] The air volume update switch 52 selects whether to output the air volume step Qstep as is or to output it to the adder 54 based on the count value of the control timer 53. When the air volume update switch 52 is connected to the adder 54, an update process for the air volume step Qstep is executed. The part including the air volume update switch 52 corresponds to step S001 in Fig. 15, and when the count value of the control timer 53 becomes equal to or greater than the air volume change period Ti, the process proceeds to the air volume update process.

[0038] Subtractor 55 calculates a difference ΔV1 between target voltage V* corresponding to the target static pressure and detected voltage V corresponding to the static pressure detected by supply pressure sensor 25. The part including subtractor 55 corresponds to steps S003 and S004 in FIG.

[0039] The multiplier 56 multiplies the difference ΔV1 by a gain G1 serving as a first control gain. The gain G1 can be expressed by the following equation (1): G1=1 / step increase / decrease determination threshold K (1)

[0040] However, as described above, when determining the first change in air volume, the step increase / decrease determination initial threshold value K1 stored in the storage unit 41 is used as the step increase / decrease determination threshold value K, and when determining the second or subsequent change in air volume, the step increase / decrease determination threshold value K is updated as shown in Fig. 17 (to be described later) before the calculation is performed by the multiplier 56. Therefore, the calculation by the multiplier 56 is performed using the step increase / decrease determination threshold value K updated by the update process for the step increase / decrease determination threshold value K shown in Fig. 17.

[0041] When the multiplication result of multiplier 56 exceeds step increase / decrease upper / lower limit value ΔQsup, step increase / decrease upper / lower limiter 57 limits the multiplication result by step increase / decrease upper / lower limit value ΔQsup, and when the multiplication result of multiplier 56 falls below step increase / decrease lower limit value ΔQinf, step increase / decrease upper / lower limiter 57 limits the multiplication result by step increase / decrease lower limit value ΔQinf. Step increase / decrease upper / lower limiter 57 outputs air volume step increase / decrease value ΔQstep. The part including multiplier 56 and step increase / decrease upper / lower limiter 57 corresponds to steps S005, S006, and S008 in FIG. 15 .

[0042] The adder 54 adds the air volume step Qstep and the air volume step increase / decrease value ΔQstep, and updates the air volume step Qstep by setting the addition result as the new air volume step Qstep. The part including the adder 54 corresponds to step S009 in FIG. 15.

[0043] In this way, subtractor 55, multiplier 56, and step increase / decrease upper / lower limiter 57 are configured to include multiplier 56 and adder 54, and calculate the air volume step increase / decrease value ΔQstep, which is the air volume change amount, by multiplying the difference between target voltage V* and detected voltage V by gain G1, and periodically changes the air volume step Qstep, which is the air volume command value for supply air blower 22, using the calculated air volume step increase / decrease value ΔQstep.

[0044] The reference voltage update switch 60 is turned ON immediately after processing by the multiplier 56. The reference voltage update switch 60 outputs the detected voltage V corresponding to the static pressure detected by the intake air pressure sensor 25 as the reference voltage V'. In other words, the reference voltage update switch 60 updates the reference voltage V' with the detected voltage V. The reference voltage V' is a value used to derive the amount of change in the detected voltage V obtained by changing the airflow rate according to the airflow step increase / decrease value ΔQstep for each airflow rate change period Ti. Note that the reference voltage update switch 60 only needs to be turned ON during the period from when processing by the multiplier 56 ends until the detected voltage V is updated to the next value.

[0045] Next, FIG. 17 will be described. The configuration in FIG. 17 corresponds to step S007 in FIG. 15. The step increase / decrease determination threshold K is calculated using the amount of change in the detected voltage V obtained by changing the air volume step Qstep by the air volume step increase / decrease value ΔQstep. A specific explanation will be given below. The subtractor 62 calculates the difference ΔV2 between the reference voltage V' and the detected voltage V. That is, the subtractor 62 obtains the difference between the detected voltage V in the previous air volume change period Ti and the detected voltage V in the current air volume change period Ti. The absolute value converter 63 calculates the absolute value |ΔV2| of the difference ΔV2. The multiplier 64 multiplies the absolute value |ΔV2| of the difference ΔV2 by a gain G2 as a second control gain. The gain G2 can be expressed by the following equation (2): G2=1 / (|ΔQstep|+1) (2)

[0046] The control block in FIG. 17 can be summarized as follows: K=|ΔV2| / (|ΔQstep|+1) (3)

[0047] In equations (2) and (3), the denominator "+1" takes into account the fact that the supply air blower 22 installed in the ventilation system is designed to output airflow in 5% increments of the rated airflow. That is, because the amount of change in static pressure when the airflow step Q is changed by one step varies depending on the airflow step Q, as in the calculation formula for K above, the airflow step Q is actually changed by "4" instead of "3," and the step increase / decrease threshold K is updated accordingly. This allows the voltage V detected by the supply air pressure sensor 25 to converge stably and quickly to the target voltage V*. The constant value "+1" to be added is not fixed but can be changed as needed, taking into account the specifications of the supply air blower 22 installed in the ventilation system.

[0048] In this way, by using the configuration for updating reference voltage V' based on detected voltage V and the configuration for updating step increase / decrease determination threshold K shown in Fig. 17, step increase / decrease determination threshold K for determining gain G1, which is the first control gain, is updated using air volume step increase / decrease value ΔQstep, which is the amount of change in air volume of supply air blower 22, and difference ΔV2, which is the amount of change in detected voltage V obtained by the change in air volume due to air volume step increase / decrease value ΔQstep. The updated step increase / decrease determination threshold K is used to calculate air volume step increase / decrease value ΔQstep of supply air blower 22 for the next cycle.

[0049] FIG. 18 is a diagram showing an example of airflow step adjustment of the ventilation device according to the first embodiment and the change in static pressure value over time. In FIG. 18, six airflow change determinations are performed for each airflow change period Ti from the start time Ts. In the upper diagram of FIG. 18, the airflow step Qstep determined for each airflow change period Ti is shown by a thick solid line. In the middle diagram of FIG. 18, the operating state of the ventilation device and the airflow step Qstep determined for each airflow change period Ti are shown. In the lower diagram of FIG. 18, the change in static pressure value over time for each airflow change period Ti is shown.

[0050] The ventilation device starts operation at a start time Ts, determines an initial air volume step Qstep, determines an air volume change every air volume change period Ti, and determines the air volume step increase / decrease value ΔQstep and the air volume step Qstep. At the start time Ts, the initial air volume step Qstep is set to a preset value of "5." At this start time Ts, a gain G1 is determined using an initial step increase / decrease threshold K1.

[0051] In the first determination after the air volume change period Ti has elapsed from the start time Ts, the air volume step increase / decrease value ΔQstep = +3 due to rounding processing by the step increase / decrease upper / lower limiter 57, and the air volume step Qstep is "8". In this case, the step increase / decrease upper / lower limiter 57 has a step increase / decrease upper limit value ΔQsup = +3 and a step increase / decrease lower limit value ΔQinf = -3, and +2 minutes has been rounded off. In this first determination after the air volume change period Ti has elapsed from the start time Ts, the gain G1 is determined using the step increase / decrease determination threshold value K2 described above.

[0052] In the second determination after 2Ti has elapsed from the start time Ts, the air volume step increase / decrease value ΔQstep is +3, and the air volume step Qstep is 11. In the second determination after 2Ti has elapsed from the start time Ts, the gain G1 is determined using the further updated step increase / decrease determination threshold K. Hereinafter, a description of the update of the step increase / decrease determination threshold K will be omitted.

[0053] In the third determination after 3Ti has elapsed since the start time Ts, the air volume step increase / decrease value ΔQstep is +2, and the air volume step Qstep is "13".

[0054] In the fourth determination after 4Ti has elapsed since the start time Ts, the air volume step increase / decrease value ΔQstep is +1, and the air volume step Qstep is "14".

[0055] In the fifth determination after 5Ti has elapsed since the start time Ts, the air volume step increase / decrease value ΔQstep is ±0, and the air volume step Qstep is "14".

[0056] In the sixth determination after 6Ti has elapsed since the start time Ts, the air volume step increase / decrease value ΔQstep is ±0, and the air volume step Qstep is "14".

[0057] By adjusting the air volume step Qstep for each air volume change period Ti in this way, the static pressure value can be quickly converged to the target static pressure P* (target voltage V*) without generating vibrations due to overshoot, as shown in the lower diagram of FIG. 18, and stable and quick response to changes in static pressure can be achieved.

[0058] According to the first embodiment, control device 24 calculates airflow step increment / decrement ΔQstep, which is the amount of airflow change, by multiplying gain G1 by difference ΔV1 between target voltage V* and detected voltage V, and periodically changes airflow step Qstep, which is the airflow command value for supply air blower 22, using the calculated airflow step increment / decrement ΔQstep. Then, control device 24 updates step increment / decrement threshold K for determining gain G1 using airflow step increment / decrement ΔQstep of supply air blower 22 and difference ΔV2, which is the amount of change in detected voltage V obtained by the change in airflow due to airflow step increment / decrement ΔQstep, and uses this updated threshold K to calculate airflow step increment / decrement ΔQstep for the next cycle. Therefore, the airflow is controlled to stably and quickly match the target static pressure whether the static pressure is rising or falling, so that the airflow in the branch duct can be kept constant stably and quickly under constant static pressure control.

[0059] 19 is a conceptual diagram showing the configuration of a ventilation device according to a second embodiment. The ventilation device includes a ventilation device main body 21, an intake air blower 22, an exhaust air blower 23, a control device 24, an intake air pressure sensor 25a, a return air pressure sensor 25b, an outside air duct 30, an intake air duct 31, a return air duct 33, and an exhaust duct 32. The outside air duct 30 and the intake air duct 31 form an intake air passage 34, and the return air duct 33 and the exhaust duct 32 form an exhaust air passage 35.

[0060] The intake air blower 22 is disposed inside the ventilation device main body 21 in the intake air duct 34. By operating the intake air blower 22, outdoor air is supplied into the room. The exhaust air blower 23 is disposed inside the ventilation device main body 21 in the exhaust air duct 35. By operating the exhaust air blower 23, indoor air is exhausted to the outside.

[0061] The supply air duct 31 has a collecting duct 38 and branch ducts 31-1 and 31-2. The supply air duct 31 branches into branch duct 31-1 and branch duct 31-2 via the collecting duct 38 and leads to an indoor air outlet (not shown). The return air duct 33 has a collecting duct 39 and branch ducts 33-1 and 33-2. The return air duct 33 branches into branch duct 33-1 and branch duct 33-2 via the collecting duct 39 and leads to an indoor air inlet (not shown). The supply air pressure sensor 25a is located inside the collecting duct 38. The return air pressure sensor 25b is located inside the collecting duct 39. In the second embodiment, the supply air duct 31 has two branch ducts 31-1 and 31-2, and the return air duct 33 has two branch ducts 33-1 and 33-2, but the number of branch ducts is not limited thereto.

[0062] FIG. 20 is a block diagram showing the configuration of a control device 24 of a ventilation system according to the second embodiment. The control device 24 includes a control program 40, a storage unit 41, a blower driver 42, and a sensor input unit 43. The control program 40 includes an air volume calculation unit 40A and a storage control unit 40B. The storage unit 41 is a nonvolatile memory and stores data that needs to be retained and managed when executing the control according to the second embodiment. Specifically, the storage unit 41 stores the target voltage V*, an initial threshold K1 for determining step increase / decrease, upper and lower step increase / decrease limits ΔQsup and ΔQinf, and an air volume change period Ti. The supply air blower 22 and the exhaust air blower 23 are connected to the blower driver 42. The supply air pressure sensor 25a and the return air pressure sensor 25b are connected to the sensor input unit 43.

[0063] Supply air blower 22 is driven and controlled based on the detection output of supply air pressure sensor 25a as described in embodiment 1. Exhaust air blower 23 is also driven and controlled based on the detection output of return air pressure sensor 25b in the same manner as supply air blower 22 described in embodiment 1. That is, control device 24 controls the air volume of exhaust air blower 23 so that the second detection value of return air pressure sensor 25b becomes the second target value. Furthermore, the control device 24 calculates the air volume step increase / decrease value ΔQstep, which is the air volume change amount, by multiplying the difference between the second target value and the second detection value by the third control gain, which is the gain G1 mentioned above, and periodically changes the air volume step Qstep, which is the air volume command value for the exhaust blower 23, using the calculated air volume step increase / decrease value ΔQstep.The control device 24 updates the third control gain using the air volume step increase / decrease value ΔQstep of the exhaust blower 23 and the change in static pressure of the return air duct 33 obtained by the change in air volume due to the air volume step increase / decrease value ΔQstep of the exhaust blower 23, and uses this third control gain to calculate the air volume step increase / decrease value ΔQstep of the exhaust blower 23 for the next cycle.

[0064] As described above, according to the second embodiment, the supply air blower 22 is driven and controlled based on the static pressure value detected by the supply air pressure sensor 25a, and the exhaust air blower 23 is driven and controlled based on the static pressure value detected by the return air pressure sensor 25b. Therefore, even if the environments of the supply air duct 31 and the return air duct 33 are different, stable and rapid air volume control toward the respective target static pressures can be performed. Therefore, a constant air volume can be ensured regardless of the installation environment of the ventilation device.

[0065] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, or embodiments may be combined with each other, and some of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0066] 1, 21 Ventilation device main body, 2, 22 Intake air blower, 4, 24 Control device, 5, 25, 25a Intake air pressure sensor, 12, 38, 39 Collecting duct, 13-1, 13-2, 13-3, 31-1, 31-2, 33-1, 33-2 Branch duct, 14-1, 14-2, 14-3 Switch, 15 Subtractor, 16 Multiplier, 17 Upper and lower limiter, 23 Exhaust air blower, 25b Return air pressure sensor, 30 Outside air duct, 31 Intake air duct, 32 Exhaust air duct, 33 Return air duct, 34 Intake air duct, 35 Exhaust air duct, 40 Control program, 40A Air volume calculation unit, 40B Memory control unit, 41 Memory unit, 42 Blower drive unit, 43 Sensor input unit, 52 Air volume update switch, 53 control timer, 54 adder, 55 subtractor, 56 multiplier, 57 step increase / decrease upper / lower limiter, 60 reference voltage update switch, 62 subtractor, 63 absolute value converter, 64 multiplier, K, K2 step increase / decrease judgment threshold, K1 step increase / decrease judgment initial threshold, Qstep air volume step, ΔQstep air volume step increase / decrease value, Ti air volume change period, ΔQinf step increase / decrease lower limit value, ΔQsup step increase / decrease upper limit value.

Claims

1. A ventilation system comprising: an air supply duct having a plurality of branch ducts that can be opened and closed individually; an air supply blower that supplies air to said air supply duct; an air supply pressure sensor that detects the static pressure of said air supply duct; and a control device that controls the air volume of said air supply blower so that a first detection value of said air supply pressure sensor becomes a first target value, wherein said control device calculates an air volume change amount by multiplying the difference between said first target value and said first detection value by a first control gain, and periodically changes an air volume command value for said air supply blower using the calculated air volume change amount, and updates said first control gain using said air volume change amount of said air supply blower and the change in the first detection value obtained by the change in air volume due to said air volume change amount of said air supply blower, and uses this first control gain to calculate the air volume change amount of said air supply blower for the next cycle.

2. The ventilation device according to claim 1, characterized in that the control device updates the first control gain by adding a constant value to the airflow change amount.

3. A ventilation device as described in claim 1, further comprising: a return air duct having a plurality of branch ducts that can be opened and closed individually; an exhaust fan that exhausts air from the return air duct; and a return air pressure sensor that detects the static pressure of the return air duct, wherein the control device controls the air volume of the exhaust fan so that a second detection value of the return air pressure sensor becomes a second target value; calculates an air volume change amount by multiplying the difference between the second target value and the second detection value by a third control gain; periodically changes the air volume command value of the exhaust fan using the calculated air volume change amount; and updates the third control gain using the air volume change amount of the exhaust fan and the change amount in the second detection value obtained by the change in air volume due to the air volume change amount of the exhaust fan, and uses the third control gain to calculate the air volume change amount of the exhaust fan in the next cycle.

4. A control method for a ventilation device comprising an air supply duct having a plurality of branch ducts that can be opened and closed individually, an air supply blower that supplies air to the air supply duct, and an air supply pressure sensor that detects the static pressure of the air supply duct, and which controls the air volume of the air supply blower so that a first detection value of the air supply pressure sensor becomes a first target value, the control method comprising: calculating an air volume change amount by multiplying the difference between the first target value and the first detection value by a first control gain; periodically changing the air volume command value of the air supply blower using the calculated air volume change amount; and updating the first control gain using the air volume change amount of the air supply blower and the change amount in the first detection value obtained by the change in air volume due to the air volume change amount of the air supply blower, and using this first control gain to calculate the air volume change amount of the air supply blower in the next cycle.

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