How to control a ventilation fan

Abstract

To obtain a control method of a ventilation blower which can suppress stress to be applied to a rotary shaft and a gear of a stepping motor in comparison with a conventional manner.SOLUTION: There is provided a control method of a ventilation blower comprising: a damper which switches a circulation air channel connecting an air inlet with an air outlet and a ventilation air channel connecting the air inlet with an exhaust port by rotation around a rotary shaft inside a housing having the air inlet, the air outlet and the exhaust port; a stepping motor which is connected with the rotary shaft to drive the damper; and a blower which is provided inside the housing. The control method includes an abutting process, a rotary shaft opening process, and a holding process. The abutting process drives the stepping motor to become a full-open state in which the damper blocks the ventilation air channel or a full-closed state in which the damper blocks the circulation air channel to abut the damper to the inside of the housing. The rotary shaft opening process stops energization to the stepping motor to open a state of holding the rotary shaft. The holding process energizes the stepping motor to be excited and makes the rotary shaft to be in the state of being held.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a ventilation fan that switches between a plurality of air paths through which air flows inside a housing using a damper, and a control method for the ventilation fan. [Background technology]

[0002] Conventionally, many proposals have been made regarding ventilation fans having an air passage switching structure. In addition, several proposals have been made regarding the operation of the damper and the control of the stepping motor that drives the damper. For example, Patent Document 1 discloses an air conditioning system for vehicles in which a rotating member is driven by an actuator and abutted against a non-rotating member to detect a reference position, and the driving speed is changed to perform the abutting operation multiple times to improve the positional accuracy of the reference position. Stepping motors, which are one type of actuator, are often used when it is necessary to hold the stopped position after the rotor has rotated a certain angle and stopped. When rotating, the position of the rotor rotates in a step-like manner by switching the current of the stator winding, and when the position is held, the poles excited by the current are aligned with the teeth of the rotor by magnetic force to hold the position. Therefore, it is common to use stepping motors with constant current. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-314119 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the vehicle air conditioning system described in Patent Document 1, the stepping motor is excited immediately after being driven a specified distance. This causes the rotor position, i.e., the rotating shaft of the stepping motor, to be held in a state in which the damper and gears in the stepping motor are subjected to high stress. If the rotating shaft is held in a state in which stress is applied, a load is placed on the stepping motor, resulting in a problem of shortening its lifespan.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a control method for a ventilation blower that can reduce stress on the rotating shaft and gears of a stepping motor compared to conventional methods. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides a control method for a ventilation fan including a damper that switches between a circulation air passage connecting the suction port and the outlet and a ventilation air passage connecting the suction port and the outlet by rotating around a rotation shaft inside a housing having an inlet port that draws in indoor air, an outlet port that blows air into the room, and an outlet port that exhausts the air drawn in from the inlet port to the outside, a stepping motor connected to the rotation shaft that drives the damper, and a fan provided inside the housing, the control method including a butting step, a rotating shaft releasing step, and a holding step. The butting step drives the stepping motor to butt the damper against the inside of the housing so that the damper is in a fully open state where the damper blocks the ventilation air passage or in a fully closed state where the damper blocks the circulation air passage. The rotating shaft releasing step cuts off the power supply to the stepping motor to release the state in which the rotating shaft is held. The holding step energizes the stepping motor to excite it so that the rotating shaft is held. When the damper is butted against the inside of the housing, an butting step, a rotating shaft releasing step, and a holding step are carried out successively. Effect of the Invention

[0007] According to the present disclosure, it is possible to reduce the stress applied to the rotating shaft and gears of the stepping motor compared to the conventional art. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of an example of the structure of a ventilation fan according to a first embodiment; [Diagram 2] FIG. 1 is a schematic diagram showing an example of the configuration of a damper drive mechanism in a bathroom dryer; [Diagram 3] A diagram showing an example of the rotation principle of a stepping motor [Figure 4] FIG. 4 is a diagram showing an example of a current supply sequence for coils in the stepping motor of FIG. 3; [Diagram 5] A diagram showing an example of the state of the air duct when a bathroom dryer is in ventilation operation. [Figure 6] A diagram showing an example of the state of the air duct when a bathroom dryer is in heating operation. [Figure 7] A diagram showing an example of the state of the air duct during drying operation of a bathroom dryer. [Figure 8] 1 is a flowchart showing an example of a procedure of a control method for a ventilation fan according to a first embodiment. [Figure 9] FIG. 13 is a diagram showing an example of a sequence of energizing coils of a stepping motor in the control method for a ventilation fan according to the first embodiment; [Figure 10] FIG. 1 is a schematic diagram showing an example of stresses acting on a rotating shaft and gears in each step of a method for controlling a ventilation fan according to embodiment 1; [Figure 11] 11 is a flowchart showing an example of a procedure of a control method for a ventilation fan according to a second embodiment. [Figure 12] FIG. 11 is a diagram showing an example of a power supply sequence for coils of a stepping motor in a control method for a ventilation fan according to a second embodiment. [Figure 13] FIG. 11 is a diagram showing an example of a state of stress applied to a rotating shaft and a gear in each step of a control method for a ventilation fan according to a second embodiment; [Figure 14] A flowchart showing an example of a procedure of a control method for a ventilation fan according to a fourth embodiment. [Figure 15] FIG. 1 is a block diagram showing an example of a hardware configuration of a control unit provided in a ventilation fan according to the first to fourth embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ventilation fan and a control method for the ventilation fan according to embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0010] Embodiment 1 First, the overall configuration of the ventilation fan will be described. Fig. 1 is a diagram showing a schematic diagram of an example of the structure of a ventilation fan according to a first embodiment. Here, the explanation will be given taking as an example a case where the ventilation fan is a bathroom dryer 1. Bathroom dryer 1 is installed through an opening formed in ceiling 51 of bathroom 50, which is an example of a room, passing from bathroom 50 to space above the ceiling 52.

[0011] Bathroom dryer 1 comprises housing 10 and ventilation duct connection 13. Housing 10 has housing main body 11 with an air passage formed inside and an open surface facing bathroom 50, and orifice 12, which is a bottom plate provided at the opening of housing main body 11 and is provided to cover the opening of housing main body 11. Housing 10 is, in one example, a hollow rectangular parallelepiped. Orifice 12 has suction port 121 that draws in air from inside bathroom 50, and circulation outlet 122 that blows air into bathroom 50. Housing 10 has ventilation connection 111 in a position corresponding to circulation outlet 122 on the surface opposite orifice 12. Circulation outlet 122 corresponds to the outlet, and ventilation connection 111 corresponds to an exhaust port that exhausts air drawn from suction port 121 to the outside.

[0012] The ventilation duct connection part 13 is provided so as to cover the ventilation connection port 111 of the housing main body part 11 from the outside. The ventilation duct connection part 13 is connected to a ventilation duct (not shown) that exhausts the air inside the bathroom 50 to the outside. The ventilation duct connection part 13 has a ventilation exhaust port 131 at the part connected to the ventilation duct.

[0013] Bathroom dryer 1 is provided inside housing 10 with damper 14 for switching air paths, and a stepping motor (not shown) that drives damper 14. Damper 14 is provided at a position inside housing 10 where ventilation air path 101 and circulation air path 102 branch off. Ventilation air path 101 is an air path that allows air taken into housing 10 to flow to ventilation duct connection part 13, and is an air path that connects intake port 121 and ventilation connection port 111. Circulation air path 102 is an air path that allows air taken into housing 10 to flow to bathroom 50, and is an air path that connects intake port 121 and circulation outlet 122.

[0014] In the example shown in Fig. 1, damper 14 is placed below ventilation connection port 111 inside housing 10, and is formed like a plate with flat tip and base ends and a curved middle portion. Damper 14 rotates around damper rotation shaft 141 provided at the base end. Bathroom dryer 1 is equipped with a damper drive mechanism that includes a stepping motor that rotates damper 14 around damper rotation shaft 141. The damper drive mechanism is an example of a drive-related part.

[0015] 2 is a diagram showing a schematic diagram of one example of the configuration of a damper drive mechanism in a bathroom dryer. Damper drive mechanism 30 has sector gear 31, small gear 32, and stepping motor 33. Sector gear 31 and small gear 32 are combined to form a reducer, or gear, that drives damper 14.

[0016] The sector gear 31 is fixed to the damper rotating shaft 141 at its sector-shaped pivot portion. The sector gear 31 is also fixed to the base end of the damper 14 at its sector surface. The pinion gear 32 is disposed so as to mesh with the teeth of the sector gear 31. The stepping motor 33 is a driving means for rotating the pinion gear 32 about the center of the pinion gear 32 as an axis. In other words, the pinion gear 32 is connected to a rotating shaft which is the output shaft of the stepping motor 33, and can be rotated by the stepping motor 33.

[0017] By driving the stepping motor 33, the small gear 32 fixed to the rotation shaft of the stepping motor 33 rotates, and the sector gear 31 rotates around the damper rotation shaft 141 in response to the rotation of the small gear 32. Since the damper 14 is fixed to the sector gear 31 and the damper rotation shaft 141, the damper 14 rotates around the damper rotation shaft 141 in response to the rotation of the sector gear 31. In other words, the rotation is transmitted from the small gear 32 attached to the rotation shaft of the stepping motor 33 to the sector gear 31 attached to the damper rotation shaft 141, and the damper 14 is driven.

[0018] Then, the rotation of damper 14 adjusts the opening degree of ventilation air passage 101 and the opening degree of circulation air passage 102. In the first embodiment, as described later, in order to position stepping motor 33, i.e., to determine the reference position, damper 14 is rotated and abutted against the inside of housing 10. After this, power supply to stepping motor 33 is temporarily stopped and the stress on the parts related to stepping motor 33 and damper 14 is released, followed by excitation.

[0019] Returning to FIG. 1, bathroom dryer 1 has blower 15, motor 16, heater 17, filter 18, design panel 19, and control unit 20. Blower 15 is provided inside housing 10. Blower 15 takes in air from bathroom 50 through suction port 121 into housing 10, generating an air flow inside housing 10. In one example, blower 15 is a single-suction sirocco fan. In the example of FIG. 1, blower 15 is arranged upstream of ventilation air duct 101 and circulation air duct 102 so as to face suction port 121. Motor 16 drives blower 15. In the example of FIG. 1, motor 16 is arranged outside housing 10.

[0020] The heater 17 is a heating unit that heats the air taken into the housing 10. The heater 17 is disposed near the circulation outlet 122. The heater 17 may be capable of switching the heating intensity. In one example, the heater 17 is an electric heater 17.

[0021] The filter 18 is positioned upstream of the intake port 121. The filter 18 removes dust and other particles from the air. The design panel 19 covers the surface of the housing 10 facing the bathroom 50. In other words, the design panel 19 covers the part of the housing 10 exposed to the bathroom 50. The design panel 19 is formed flat and is attached with a gap between the ceiling surface and the outer upward side wall of the design panel 19, and air from the bathroom 50 is sucked in through the gap around the entire circumference of the design panel 19. An opening, the blowing section 191, is provided at a position corresponding to the circulation blowing port 122 of the design panel 19. Air that has passed through the circulation air duct 102 is blown out from the blowing section 191 into the bathroom 50.

[0022] Control unit 20 controls bathroom dryer 1. Specifically, control unit 20 has a memory element in which a predetermined control program is stored, and in response to operation commands input from a remote controller (not shown), controls blower 15, heater 17 and damper 14 individually, causing bathroom dryer 1 to perform heating operation, ventilation operation, drying operation, etc.

[0023] Bathroom dryer 1 drives blower 15 to take air from bathroom 50 into casing 10. In heating operation, bathroom dryer 1 blows out air that has passed through circulation air duct 102 and has been heated by heater 17 into bathroom 50. In ventilation operation, bathroom dryer 1 sends out air from ventilation air duct 101 to ventilation duct connection 13. In drying operation, bathroom dryer 1 sends out air that has been taken into casing 10 from ventilation air duct 101 to ventilation duct connection 13, and blows out air that has passed through circulation air duct 102 and has been heated by heater 17 into bathroom 50. In drying operation, bathroom dryer 1 may blow out cool air instead of warm air into bathroom 50. Switching between heating operation, ventilation operation, and drying operation is done according to the position at which damper 14 is arranged.

[0024] The control unit 20 switches between the heating operation, the ventilation operation, and the drying operation by controlling the blower 15, the damper 14, and the heater 17. In the first embodiment, when the circulation air passage 102 or the ventilation air passage 101 is blocked, the control unit 20 rotates the damper 14 to abut the damper 14 against the inside of the housing 10, and after the abutment occurs, the power supply to the stepping motor 33 is cut off to release the holding of the rotating shaft of the stepping motor 33, and then the power is supplied to the stepping motor 33 again to hold the rotating shaft so that it does not rotate due to an external force.

[0025] Fig. 3 is a diagram showing an example of the rotation principle of a stepping motor. Fig. 3 shows a wiring diagram of coils 332 arranged around a rotor 331 of a stepping motor 33. The stepping motor 33 has a rotor 331 and coils 332 wound around a stator (not shown). A base pin 333 is connected to each coil 332. A pin number that identifies the base pin 333 is assigned to the base pin 333.

[0026] FIG. 4 is a diagram showing an example of the energization sequence of the coils in the stepping motor of FIG. 3. Here, the energization sequence, i.e., the excitation sequence, when the stepping motor 33 is rotated counterclockwise as viewed from the direction of the rotation axis with 1-2 phase excitation is shown. In this diagram, "+" indicates that a positive voltage is applied to the base pin 333, and "-" indicates that a negative voltage is applied to the base pin 333. By applying a voltage to the base pin 333 in order from step "1" to "8", the rotor 331 rotates counterclockwise. In this way, the coil 332 to be energized is changed for each step to rotate the rotation axis. In other words, the coil 332 to be excited can be switched to rotate one step at a time. If you want to stop the rotation and hold it at that position, you can continue excitation without proceeding to the next step.

[0027] Conventionally, when the stepping motor 33 is driven in this manner and the damper 14 hits the rotor shaft as the rotor shaft rotates, the coil 332 is kept energized to maintain the hit state. This causes stress to be applied to the damper 14, the sector gear 31 and the pinion 32, which are gears, and the rotor shaft of the stepping motor 33.

[0028] However, in the first embodiment, when abutment occurs, the control unit 20 temporarily stops the supply of electricity to the stepping motor 33. This releases the rotating shaft of the stepping motor 33, and the rotating shaft is not held. In this state, the rotating shaft rotates in the reverse direction due to the elastic deformation stress of the damper 14, and the stress on the rotating shaft and the gears is reduced. Thereafter, the stepping motor 33 is energized to excite it, and the rotating shaft is held. This makes it possible to reduce the stress on each part compared to when abutment occurs.

[0029] Next, ventilation, heating, and drying operations of bathroom dryer 1 of the first embodiment will be described. FIG. 5 is a diagram showing an example of the state of the air passage during ventilation operation of the bathroom dryer. The white arrows in FIG. 5 indicate the flow of air. The same applies to the following figures. In ventilation operation, damper 14 is arranged to prevent air from bathroom 50 from flowing toward blow-out section 191 via heater 17 and to flow toward ventilation connection port 111, forming ventilation air passage 101. That is, damper 14 fully closes circulation air passage 102 and is in a state where it abuts against a member inside housing 10. In this example, the tip of damper 14 abuts against orifice 12. As a result, ventilation air passage 101 is formed inside housing 10. In addition, the reference position is detected by abutting damper 14 against orifice 12. When blower 15 starts operating, air in bathroom 50 flows through ventilation air passage 101 from intake port 121. That is, the air in bathroom 50 is guided by damper 14 to ventilation connection port 111 and exhausted to the outdoors via ventilation duct connection part 13.

[0030] In bathroom dryer 1, damper 14 performs the abutting operation as described above when switching from heating operation to ventilation operation, from drying operation to ventilation operation, and from stopped to ventilation operation. To close circulation outlet 122, damper 14 performs the abutting operation with its tip in contact with orifice 12. Then, electricity to stepping motor 33 is temporarily stopped to release the stress, and electricity is then passed again to excite it. This makes it possible to close circulation outlet 122 in a state where the stress on the rotating shaft and gears of stepping motor 33 is weaker than the stress applied during the abutting operation.

[0031] FIG. 6 is a diagram showing an example of the state of the air passage during heating operation of the bathroom dryer. In heating operation, ventilation connection port 111 is closed, and damper 14 is arranged so that air from bathroom 50 flows toward blowout section 191 via heater 17, forming circulation air passage 102. That is, damper 14 is in a fully open state that closes ventilation air passage 101, and is in a state where it hits a member inside housing 10. In this example, the tip of damper 14 is in a state where it hits the upper surface of housing 10. As a result, circulation air passage 102 is formed inside housing 10. Also, by hitting damper 14 against the upper surface of housing 10, the reference position is detected. Then, heating operation is possible in which air taken in from bathroom 50 is heated by heater 17 and returned to bathroom 50. In heating operation, air from bathroom 50 is taken into housing 10 by driving blower 15. The air taken into the inside of the housing 10 by the blower 15 passes through the circulation air passage 102, is heated by the heater 17, and then is blown out from the outlet part 191 via the circulation outlet 122 into the bathroom 50.

[0032] In bathroom dryer 1, damper 14 performs the abutting operation as described above when switching from ventilation operation to heating operation, from drying operation to heating operation, and from stopped to heating operation. To close ventilation connection port 111, damper 14 performs the abutting operation with its tip in contact with the top surface of housing 10. Then, electricity to stepping motor 33 is temporarily stopped to release the stress, and electricity is then passed again to excite it. This makes it possible to close circulation outlet 122 in a state where the stress on the rotating shaft and gears of stepping motor 33 is weaker than the stress applied during the abutting operation.

[0033] FIG. 7 is a diagram showing an example of the state of the air passage during drying operation of the bathroom dryer. In drying operation, damper 14 is arranged to form circulation air passage 102, through which part of the air taken in from bathroom 50 is heated by heater 17 and returned to bathroom 50 from blowing section 191, and ventilation air passage 101, through which the remaining air is exhausted to the outdoors from ventilation connection port 111. That is, damper 14 is held in a position between orifice 12 and the upper surface of housing 10. This splits the air flow into two, and circulation air passage 102 heading toward heater 17 and ventilation air passage 101 heading toward ventilation connection port 111 are secured inside housing 10. In drying operation, ventilation is performed while hot air is blown out into bathroom 50, and bathroom 50 or clothes can be dried, and bathroom dryer 1 can function as a hot air dryer.

[0034] During the drying operation, the damper 14 does not come into contact with either the orifice 12 or the upper surface of the housing 10. In other words, the damper 14 does not perform abutting operation, so that the damper 14 can be excited immediately after being driven by the stepping motor 33.

[0035] Next, the method for controlling the ventilation fan according to the first embodiment will be described in detail. FIG. 8 is a flow chart showing an example of the procedure of the method for controlling the ventilation fan according to the first embodiment. FIG. 9 is a diagram showing an example of the order of energizing the coils of the stepping motor in the method for controlling the ventilation fan according to the first embodiment. Here, an example is taken of switching from a fully closed state in which the circulating air passage 102 to the inside of bathroom 50 in FIG. 5 is closed to a fully open state in which the circulating air passage 102 to the inside of bathroom 50 in FIG. 6 is opened, that is, from ventilation operation to heating operation. It is assumed that blower 15 remains in operation when the method for controlling the ventilation fan shown in FIG. 8 is being executed.

[0036] First, the control unit 20 of the ventilation blower drives the stepping motor 33 to perform the butting step (step S1). In the determined energization sequence shown in FIG. 9, a voltage is applied to the base pin 333 to excite the coil 332, causing the rotor 331 to rotate, and a forward rotation step is performed in which the damper 14 is rotated clockwise as viewed from the output shaft direction via a gear connected to the rotation shaft of the rotor 331, i.e., the rotation shaft of the stepping motor 33. In one example, the clockwise forward rotation step shown in steps "1" to "8" is executed several tens of times. This causes the rotation shaft of the stepping motor 33 to rotate, and the damper 14 connected to the rotation shaft via a gear rotates clockwise from the state of FIG. 5 to the state of FIG. 6. From the fully closed state of the circulation air passage 102 in FIG. 5 to the fully open state of the circulation air passage 102 in FIG. 6, the opening / closing angle of the damper 14 is rotated, for example, by 30°.

[0037] In the abutting process of step S1, a voltage is applied to each base pin 333 in a forward rotation step so that damper 14 rotates forward by about 10 to 20 percent more than the opening / closing angle, and damper 14 abuts against the upper surface of housing 10. When damper 14 abuts against the upper surface of housing 10, damper 14 deforms slightly and comes into close contact with the upper surface of housing 10, thereby blocking ventilation connection port 111 of upper ventilation air passage 101. At this time, stress corresponding to the elastic deformation of damper 14 is generated in the rotating shaft and gear.

[0038] Next, the control unit 20 performs a rotating shaft releasing step of cutting off the voltage application to the base pins 333 to release the rotating shaft of the stepping motor 33 (step S2). At this time, the rotating shaft rotates in the reverse direction due to the stress corresponding to the elastic deformation of the damper 14, and the stress applied to the rotating shaft and the gears is reduced. As shown in Fig. 9, no voltage is applied to any of the base pins 333.

[0039] Thereafter, the control unit 20 performs a holding step of applying a voltage to the determined position of the base pin 333 (step S3). In one example, as shown in Fig. 9, the coil 332 corresponding to the state of "1" of the forward rotation step is excited, and the rotating shaft is held at the position of "1" of the forward rotation step. This ends the method of controlling the ventilation fan.

[0040] Fig. 10 is a diagram showing an example of the state of stress on the rotating shaft and the gears in each step of the control method for the ventilation fan according to embodiment 1. In this diagram, the horizontal axis indicates time, and the vertical axis indicates stress on the rotating shaft and the gears. Here, for ease of understanding, the horizontal axis also indicates the steps in Figs. 8 and 9.

[0041] Time T1-1 corresponds to the rotational position of damper 14 when circulating air passage 102 in Fig. 5 is in a fully closed state. In the abutting process of step S1, the rotating shaft of damper 14 is rotated in the forward direction, i.e., clockwise from the state in Fig. 5 to the state in Fig. 6. As a result, damper 14 is in a slightly floating state at time T1-2. In this state, rotational stress due to the damper 14's own weight acts on the rotating shaft and gear. Until time T1-3, rotational stress due to the damper 14's own weight acts on the rotating shaft and gear.

[0042] When the rotary shaft of damper 14 is further rotated in the forward direction, air circulation path 102 is fully opened as shown in Fig. 6. That is, at time T1-3, damper 14 abuts against the upper surface of housing 10, closing ventilation connection port 111 and bringing air circulation path 102 into the fully open state.

[0043] When the rotation shaft of damper 14 is further rotated in the forward direction from the state where damper 14 is abutted against the upper surface of housing 10, damper 14 undergoes elastic deformation while rotating damper rotation shaft 141. At this time, a stress that is the sum of a rotational stress due to the weight of damper 14 and a stress due to the elastic deformation of damper 14 acts on the rotation shaft of stepping motor 33.

[0044] When the damper rotating shaft 141 is further rotated in the forward direction and the stress applied to the rotating shaft increases, slippage occurs between the stator and rotor 331 of the stepping motor 33. Therefore, no greater stress acts on the rotating shaft. The state in which the rotational stress of the rotating shaft is balanced with the slip torque of the stepping motor 33 is time T1-4, and the stress at this time is St-14. If a rotation command is issued to the stepping motor 33 any further, slippage will occur and the stress will not increase. In other words, the stress remains constant until time T2-1, which is the end of the abutment process in step S1.

[0045] Next, in the rotating shaft releasing process of step S2, at time T2-1, the voltage application to the base pin 333 is cut off to release the rotating shaft. At this time, the rotating shaft rotates in the reverse direction due to the elastic deformation stress of the damper 14, and the stress applied to the rotating shaft and the gear is reduced. That is, in response to the reverse rotation of the rotating shaft, the stress is reduced from St-14 to St-22 between time T2-1 and time T2-2.

[0046] The gear of the rotating shaft has a frictional force against rotation, and even when the rotating shaft is in a released state, the stress does not become completely zero, and the rotating shaft is maintained in a constant stress state. This state continues from time T2-2 to time T3-1 when the holding step of step S3 is started.

[0047] After that, in the holding process of step S3, at time T3-1, a voltage is applied to the base pin 333 corresponding to the state of forward rotation step "1" in FIG. 9. This holds the rotating shaft at the position of forward rotation step "1". At this time, the rotating shaft and the gear are held in the stress state at time T3-1, that is, in the state in which stress St-22 is applied. In other words, when the damper 14 is in the fully open state blocking the ventilation air passage 101 or in the fully closed state blocking the circulation air passage 102, the rotating shaft of the stepping motor 33 is in a state in which a stress equal to the frictional force of the rotating shaft is applied. This ends the process.

[0048] In this manner, in the first embodiment, the voltage applied to the coil 332 is cut off after the impact, and the rotating shaft is released. As a result, the elastic deformation stress of the damper 14 rotates the rotating shaft in the opposite direction to the rotation direction at the time of the impact. In other words, since the rotating shaft is not held and can rotate, the elastic deformation stress of the damper 14 is released by the rotation of the rotating shaft in the opposite direction. As a result, as shown in FIG. 10, the stress applied to the rotating shaft can be reduced from St-14 to St-22. In other words, it can be reduced to the same stress as the friction force against the rotation of the gear of the rotating shaft. Thereafter, a voltage is applied to the coil 332 to excite it, and the rotating shaft is held at a determined position. As a result, the stress due to the impact operation at the time of determining the reference position is alleviated, and the stress applied to the rotating shaft and the gear can be reduced compared to the conventional ventilation blower in which the rotating shaft is held in the state of the stepping motor 33 in which the impact occurs in the damper 14. This reduces the deterioration of the driving parts of the stepping motor 33 and the damper 14, and the life of the ventilation blower can be extended.

[0049] Embodiment 2 The configuration of the ventilation fan according to the second embodiment is similar to that described in the first embodiment. However, the process performed by the control unit 20 after the damper 14 hits the wall is different. The differences from the first embodiment will be described below.

[0050] After the butting operation, the control unit 20 of the ventilation blower according to the second embodiment cuts off the voltage application to the base pin 333 to release the rotating shaft, and further rotates the stepping motor 33 in the reverse direction by several pulses. In other words, the stress on the stepping motor 33 and the drive-related components of the damper 14 is actively reduced. Thereafter, the control unit 20 applies a voltage to the base pin 333 at a position that will result in a determined state, thereby exciting it. The reverse rotation is performed in the direction opposite to the rotation direction in which the butting operation is performed, by several rotations.

[0051] Next, a method for controlling a ventilation fan according to the second embodiment will be described in detail. FIG. 11 is a flow chart showing an example of the procedure of the method for controlling a ventilation fan according to the second embodiment. FIG. 12 is a diagram showing an example of the order of energizing the coils of a stepping motor in the method for controlling a ventilation fan according to the second embodiment. Here, an example is taken of an operation from a fully closed state in which circulating air passage 102 to the inside of bathroom 50 in FIG. 5 is closed to a fully open state in which circulating air passage 102 to the inside of bathroom 50 in FIG. 6 is opened, that is, a case of switching from ventilation operation to heating operation. Note that, in the following, the same steps as those in FIG. 8 of the first embodiment are denoted by the same step numbers, and different parts will be described. Also, when the method for controlling a ventilation fan shown in FIG. 11 is being executed, blower 15 remains in operation.

[0052] As in Fig. 8 of the first embodiment, the control unit 20 of the ventilation blower performs a butting process in step S1 and a rotating shaft opening process in step S2. As in the first embodiment, in the determined energization sequence shown in Fig. 12, a voltage is applied to the base pin 333 to excite the coil 332, causing the rotor 331 to rotate, and a forward rotation step is performed several dozen times to rotate the damper 14 in the clockwise direction as viewed from the rotating shaft direction of the rotor 331. After that, as shown in Fig. 12, all the base pins 333 are in an open state with no voltage applied thereto.

[0053] Next, the control unit 20 executes a reverse rotation step of rotating the rotating shaft in the reverse direction (step S11). At this time, by rotating the rotating shaft further back than the holding state with the same stress as the frictional force against the rotation of the gear of the rotating shaft, the stress applied to the rotating shaft and the gear is reduced compared to the rotating shaft release step of step S2. In the predetermined excitation order shown in the reverse rotation step of FIG. 12, a voltage is applied to the base pin 333 to excite the coil 332, causing the rotor 331 to rotate, and a reverse rotation step is performed in which the damper 14 is rotated counterclockwise when viewed from the output shaft direction by the rotating shaft of the rotor 331. In one example, the counterclockwise reverse rotation step shown in steps "8" to "1" is executed several times. This causes the stepping motor 33 to rotate in the reverse direction.

[0054] For example, when the rotation shaft of the damper 14 is horizontal and a collision occurs below in the vertical direction, even if the rotation shaft releasing step is performed, the damper 14 cannot rotate in a direction against gravity, so the stress applied to the rotation shaft and gears may not be reduced much. Also, when the rotation shaft of the damper 14 is vertical, it is difficult to release the stress for the same reason. In such a case, it is possible to reduce the stress applied to the rotation shaft and gears by rotating the rotation shaft in the opposite direction.

[0055] After that, the holding step of step S3 is executed. In one example, as shown in Fig. 12, the coil 332 is excited and the rotating shaft is held at the position of the forward rotation step "1". This is the end of the control method for the ventilation blower.

[0056] Fig. 13 is a diagram showing an example of the state of stress on the rotating shaft and the gears in each step of the control method for the ventilation fan according to the second embodiment. In this diagram, the horizontal axis indicates time, and the vertical axis indicates stress on the rotating shaft and the gears. Here, for ease of understanding, the horizontal axis also indicates the steps in Fig. 11 and Fig. 12. Note that a description of the same parts as in Fig. 10 of the first embodiment will be omitted, and only different parts will be described.

[0057] In the second embodiment, in the reverse rotation step of step S11 after the rotating shaft releasing step of step S2, the rotating shaft is rotated in the reverse direction at time T11-1. At this time, by rotating the rotating shaft back further than the state in which the same stress as the frictional force against the rotation of the gear of the rotating shaft is maintained, the stress applied to the rotating shaft and the gear is reduced compared to the rotating shaft releasing step of step S2. That is, in response to the reverse rotation of the rotating shaft, the stress is reduced from St-22 to St-112 between time T11-1 and time T3-1.

[0058] After that, in the holding process of step S3 at time T3-1, the control unit 20 applies a voltage to the base pin 333 corresponding to the state of the forward rotation step "1" in FIG. 12. As a result, the rotating shaft is held at the position of the forward rotation step "1". At this time, the rotating shaft and the gear are held in the state of time T3-1, that is, in the state in which the stress St-112 is applied. In other words, when the damper 14 is in the fully open state blocking the ventilation air passage 101 or in the fully closed state blocking the circulation air passage 102, the rotating shaft of the stepping motor 33 is in a state in which a stress smaller than the frictional force of the rotating shaft is applied. This ends the process.

[0059] In this way, in the second embodiment, after the impact, the voltage applied to the coil 332 is turned off, the rotating shaft is released, and the rotating shaft is rotated in the reverse direction. This makes it possible to reduce the stress applied to the rotating shaft from St-14 to St-112 as shown in FIG. 13. In other words, it is possible to reduce the stress applied to the rotating shaft and the gear to a stress smaller than the frictional force of the rotating shaft against the rotation of the gear. The second embodiment is particularly effective in an environment in which the impact occurs in a direction in which the stress is difficult to release, such as when the rotating shaft of the damper 14 is horizontal and the impact occurs below in the vertical direction, or when the rotating shaft of the damper 14 is vertical.

[0060] Embodiment 3 In the third embodiment, a ventilation fan that combines the first and second embodiments will be described. The configuration of the ventilation fan according to the third embodiment is similar to that described in the first and second embodiments. However, the process performed by the control unit 20 after the damper 14 hits the wall is different. The following describes the differences from the first and second embodiments.

[0061] A case will be taken as an example in which the drive shaft of the damper 14 is horizontal and abutting operations are performed on the upper and lower sides in the vertical direction. In the case of rotation of the damper 14 involving abutting operations on the upper side in the vertical direction, the control unit 20 of the ventilation blower performs control according to the procedure shown in FIG. 8 of the first embodiment. That is, the control unit 20 performs a butting process of performing an upper butting operation, a rotating shaft releasing process of temporarily stopping the supply of electricity to the stepping motor 33, and a holding process of performing excitation and holding the rotating shaft, in succession. On the other hand, in the case of rotation of the damper 14 involving abutting operations on the lower side in the vertical direction, the control unit 20 performs control according to the procedure shown in FIG. 11 of the second embodiment. That is, the control unit 20 performs a butting process of performing a lower butting operation, a rotating shaft releasing process of temporarily stopping the supply of electricity to the stepping motor 33, a reverse rotation process of rotating the motor in the reverse direction by several pulses, and a holding process of performing excitation and holding the rotating shaft, in succession. In one example, the reverse rotation is performed several times, with one rotation being from step "8" to step "1" in the reverse rotation steps in Fig. 12. When striking from above, the weight of the damper 14 is utilized, and when striking from below, the stepping motor 33 is rotated in the reverse direction, thereby reducing the stress on the rotating shaft and gears.

[0062] When the upper side is butted, the rotation direction at the time of butting and the rotation direction due to the weight of the damper 14 are opposite to each other, so the stress is relieved by the rotating shaft releasing process. On the other hand, when the lower side is butted, the rotation direction at the time of butting and the rotation direction due to the weight of the damper 14 are the same, so the stress is added. In other words, even if the rotating shaft releasing process is performed, the stress is less likely to be relieved than when the upper side is butted. For this reason, it is desirable to relieve the stress by rotating the stepping motor 33 in the reverse direction.

[0063] When installing the ventilation blower, the installer can grasp whether the rotation axis of damper 14 is horizontal or not, and if the rotation axis is horizontal, whether the position where damper 14 hits is on the upper or lower side in the vertical direction. The installer sets control unit 20 to make stepping motor 33 perform the process described in embodiment 1 when the rotation axis of damper 14 is horizontal and the position where damper 14 hits is on the upper side in the vertical direction, and to make stepping motor 33 perform the process described in embodiment 2 when the position where damper 14 hits is on the lower side in the vertical direction.

[0064] The third embodiment can also provide the same effects as the first and second embodiments.

[0065] Embodiment 4 The configuration of the ventilation fan according to the fourth embodiment is similar to that described in the first to third embodiments. The following describes the differences from the first to third embodiments. In the ventilation fan according to the fourth embodiment, when controlling the abutting operation of the damper 14, the control unit 20 stops the operation of the blower 15 when the damper 14 is driven. That is, the control unit 20 stops the driving of the blower 15 before driving the damper 14, causes the damper 14 to rotate, and then drives the blower 15.

[0066] Next, a method for controlling a ventilation fan according to the fourth embodiment will be described in detail. Fig. 14 is a flow chart showing an example of the procedure of the method for controlling a ventilation fan according to the fourth embodiment. Note that, as in the second embodiment, a case in which a reverse rotation process is performed after a rotating shaft opening process will be taken as an example. In the following, the same processes as those in Fig. 8 of the first embodiment and Fig. 11 of the second embodiment will be given the same step numbers, and differences will be described.

[0067] First, the control unit 20 of the ventilation blower executes a blower stopping step for stopping the blowing of the blower 15 (step S21). If the damper 14 is operated while the blower 15 is in operation, the pressure due to the blowing of the air also acts on the rotating shaft. In addition, the blowing pressure changes due to pressure loss and the like, and becomes unstable. Therefore, in the fourth embodiment, the blower 15 is stopped before the damper 14 is rotated. As a result, the abutting operation is performed with the blowing of the blower 15 stopped, and therefore stable stress relaxation can be performed regardless of the blowing of the blower 15.

[0068] Next, the control unit 20 performs the steps from the butting step of step S1 to the holding step of step S3 described in the first and second embodiments. After the holding step of step S3, the control unit 20 performs a blower operation step of operating the blower 15 (step S22). This ends the process.

[0069] In the fourth embodiment, before the rotation operation of damper 14 accompanied by the abutting operation, the rotation operation of damper 14 accompanied by the abutting operation described in the first to third embodiments is performed with blower 15 stopped, and then blower 15 is operated. This makes it possible to suppress the pressure due to the air blowing from acting on the rotating shaft via damper 14 during the abutting operation. It is also possible to suppress the influence of the unstable air blowing pressure, which changes due to pressure loss or the like, on the rotating shaft. As a result, it is possible to achieve the effect of stable stress relaxation, regardless of the air blown by blower 15.

[0070] The control unit 20 described in the first to fourth embodiments is realized as a processing circuit. The processing circuit may be dedicated hardware, an integrated circuit, or a circuit having a processor. FIG. 15 is a block diagram showing an example of a hardware configuration of a control unit provided in the ventilation blower according to the first to fourth embodiments. The control unit 20 includes a processor 501 and a memory 502. The processor 501 is a CPU (also called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor)), a system LSI (Large Scale Integration), or the like. The memory 502 is a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc), or the like. The processor 501 and the memory 502 are connected via a bus line 503 .

[0071] The functions of the control unit 20 are realized by reading from the memory 502 a program describing the procedure of the method for controlling the ventilation fan, including the process of controlling the switching of the damper 14, and executing the program by the processor 501. The above functions may also be realized by a combination of multiple processors and multiple memories. Some of the functions of the control unit 20 may be implemented as an electronic circuit, which is dedicated hardware, and the other functions may be realized by the processor 501 and the memory 502. In one example, the control unit 20 controls the operation of the blower 15 and the damper drive unit by electric signals.

[0072] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0073] 1 bathroom dryer, 10 housing, 11 housing main body, 12 orifice, 13 ventilation duct connection, 14 damper, 15 blower, 16 motor, 17 heater, 18 filter, 19 design panel, 20 control section, 30 damper drive mechanism, 31 sector gear, 32 pinion, 33 stepping motor, 50 bathroom, 51 ceiling, 52 attic, 101 ventilation air duct, 102 circulation air duct, 111 ventilation connection port, 121 intake port, 122 circulation air outlet, 131 ventilation exhaust port, 141 damper rotating shaft, 191 outlet section, 331 rotor, 332 coil, 333 base pin.

Claims

1. A control method for a ventilation fan including a housing having an intake port for sucking in indoor air, an exhaust port for blowing air into the room, and an exhaust port for exhausting the air sucked from the intake port to the outside, a damper that switches between a circulation air passage connecting the intake port and the exhaust port and a ventilation air passage connecting the intake port and the exhaust port by rotating about a rotation shaft, a stepping motor connected to the rotation shaft for driving the damper, and a fan provided inside the housing, comprising: abutting step of driving the stepping motor to abut the damper against an inside of the housing so that the damper is in a fully open state in which the damper blocks the ventilation air passage or in a fully closed state in which the damper blocks the circulation air passage; a rotating shaft releasing step of cutting off the power supply to the stepping motor to release the state in which the rotating shaft is held; a holding step of energizing the stepping motor to excite it and hold the rotating shaft; Including, a control method for a ventilation fan, comprising the steps of: successively carrying out the abutting step, the rotating shaft releasing step, and the holding step when the damper is abutted against an inside of the housing.

2. The method further includes a reverse rotation step of rotating the rotating shaft in a direction opposite to the direction of rotation in the abutting step after the rotating shaft releasing step and before the holding step, 2. The method for controlling a ventilation fan according to claim 1, wherein the abutting step, the rotating shaft releasing step, the reverse rotation step, and the holding step are carried out consecutively when the damper is abutted against the inside of the housing.

3. When the rotating shaft is disposed in a horizontal direction and strikes against the inside of the housing at an upper side in a vertical direction in either the fully open state or the fully closed state, the striking step, the rotating shaft releasing step, and the holding step are carried out successively; 3. The control method for a ventilation fan according to claim 2, wherein when the rotating shaft strikes the inside of the housing at a vertically lower side in the other of the fully open state and the fully closed state, the striking step, the rotating shaft releasing step, the reverse rotation step, and the holding step are carried out successively.

4. 3. The method of claim 2, wherein the reverse rotation step is performed when the rotation shaft is disposed in a vertical direction.

5. 5. The method for controlling a ventilation fan according to claim 1, further comprising a blower stopping step of stopping the blowing of air by the blower before the abutting step.

Images