JP7843914B2 - Indoor unit and air conditioner - Google Patents

Description

This disclosure relates to indoor units and air conditioners in which noise may be introduced both through the power supply and through areas touched by the user.

Air conditioners can be affected by noise such as lightning strikes transmitted through the power supply. Furthermore, if an air conditioner has a device that a user can touch, touching this device can introduce static electricity and other noise. These noises can cause the control circuits of the air conditioner to malfunction, so it is desirable to properly dissipate them to ground.

The television described in Patent Document 1 comprises a radio wave receiving side wiring board and a power supply side wiring board having a power supply circuit section. The first connection point of the ground wire wired from the power supply circuit section is connected to the ground side of the tuner section and the electronic circuit section of the receiving side wiring board. As a result, the television of Patent Document 1 makes it difficult for noise such as abnormal currents due to static electricity and electromagnetic waves emitted from the tuner section and electronic circuit section to be sent to the electronic circuit section.

Japanese Patent Application Publication No. 10-322081

However, the technology described in Patent Document 1 had a problem in that if noise such as static electricity or lightning were introduced, the noise would flow through the ground pattern on the substrate, potentially causing the control circuit to malfunction depending on the pattern arrangement.

This disclosure is made in view of the above, and aims to provide an indoor unit that can prevent the control circuit from malfunctioning even when noise may be introduced from both the power supply and the user's touch.

To solve the aforementioned problems and achieve the objective, the indoor unit of this disclosure comprises a device that can be touched by the user, a first noise suppression capacitor that dissipates a first noise introduced from the AC power supply to the ground, and a second noise suppression capacitor that dissipates a second noise introduced from the device to the ground. The path through which the first noise passes through the first noise suppression capacitor and the path through which the second noise passes through the second noise suppression capacitor are different paths.

The indoor unit described herein has the effect of preventing the control circuit from malfunctioning, even when noise may be introduced from both the power supply and the user's touch.

This figure shows the external configuration of the indoor unit of the air conditioner according to Embodiment 1. Figure 1 shows the internal structure of the indoor unit when the decorative panel is opened. This diagram shows the circuit configuration of the indoor unit of the air conditioner according to Embodiment 1. Diagram showing the configuration of an air conditioner according to Embodiment 1. Diagram showing the circuit configuration of the indoor unit of the comparative example air conditioner. This diagram shows the circuit configuration of the indoor unit of the air conditioner according to Embodiment 2.

The indoor unit and air conditioner according to the embodiments of this disclosure will be described in detail below with reference to the drawings.

Embodiment 1.
Figure 1 shows the external configuration of the indoor unit of the air conditioner according to Embodiment 1. Figure 2 shows the internal structure of the indoor unit when the design panel shown in Figure 1 is opened. The air conditioner comprises an indoor unit 100 and an outdoor unit (not shown).

The indoor unit 100 is equipped with a decorative panel (top panel) 101. The decorative panel 101 is attached to the main body of the indoor unit 100 so as to be openable and closable. Inside the indoor unit 100, there are devices that can be touched by the user. Hereinafter, the devices that can be touched by the user will be referred to as tactile devices 11.

The tactile device 11 is configured to be detachable by the user, for example. The tactile device 11 is composed of, for example, two wires (or a metal plate, metal-plated resin, etc.), and suppresses viruses in the air and collects dust by applying a high voltage between the two wires. When the tactile device 11 is touched by the user, static electricity may be introduced into the indoor unit 100.

Note that in Figures 1 and 2, the components that make up the refrigeration cycle of the air conditioner, such as the outdoor unit, heat exchanger, fan, and refrigerant piping, are generic and therefore their explanation is omitted.

Figure 3 shows the circuit configuration of the indoor unit of the air conditioner according to Embodiment 1. The indoor unit 100 is connected to the AC power supply 1. The indoor unit 100 includes a filter protection circuit 2, a diode bridge 3, a smoothing electrolytic capacitor 4, a transformer circuit 5, a voltage generating diode 6, a smoothing capacitor 7, a control circuit 8, a power feedback circuit 9, and a high-voltage power supply circuit 10. The indoor unit 100 also includes a tactile device 11, a coupling capacitor (bypass capacitor) 12, noise suppression capacitors 13 and 14, and an earth terminal E1. The noise suppression capacitor 13 is the first noise suppression capacitor, and the noise suppression capacitor 14 is the second noise suppression capacitor.

In the indoor unit 100, components other than the tactile device 11 are arranged on a circuit board (hereinafter referred to as the circuit board). Specifically, the circuit board of the indoor unit 100 includes a filter protection circuit 2, a diode bridge 3, a smoothing electrolytic capacitor 4, a transformer circuit 5, a voltage generating diode 6, a smoothing capacitor 7, a control circuit 8, a power feedback circuit 9, a high-voltage power supply circuit 10, a coupling capacitor 12, noise suppression capacitors 13 and 14, and an earth terminal E1. Note that the components of the indoor unit 100 other than the tactile device 11 may be distributed across multiple circuit boards. The earth terminal E1 is an earth connection that connects the circuit board to earth (such as a block of metal). The earth terminal E1 and earth are connected by a cable or the like. The earth terminal E1 is a terminal that releases noise sent via the noise suppression capacitors 13 and 14 to earth. The earth may be located inside the indoor unit 100 or on the outdoor unit.

The filter protection circuit 2 is connected to the AC power supply 1 by two connecting wires and to the diode bridge 3 by two connecting wires. The diode bridge 3 is connected to the transformer circuit 5 by two connecting wires and to the filter protection circuit 2 by two connecting wires.

One of the connecting wires between the diode bridge 3 and the transformer circuit 5 has a connection point P1, while the other connecting wire has an upstream connection point P2 and a downstream connection point P4. The smoothing electrolytic capacitor 4 is connected to connection points P1 and P2. In addition, connection point P2 is connected to ground (GND) and connection point P4.

The transformer circuit 5 is connected to connection point P3 via a voltage generating diode 6. The transformer circuit 5 is also connected to connection points P1 and P4. Connection point P4 is connected to connection point P5 via a coupling capacitor 12. Connection point P4 is connected to connection point P2 and the coupling capacitor 12. The smoothing capacitor 7 is connected to connection points P3 and P5.

Connection point P3 is connected to connection point P6, and connection point P5 is connected to connection point P7. The power feedback circuit 9 is connected to connection points P6 and P7. Connection point P7 is connected to connection point P8. The control circuit 8 is connected to connection points P6 and P8 and the high-voltage power supply circuit 10.

The high-voltage power supply circuit 10 is connected to the tactile device 11. The high-voltage power supply circuit 10 is also connected to connection point P9. Connection point P9 is connected to connection point P8 and the noise suppression capacitor 14. The noise suppression capacitor 14 is connected to connection point P10 via connection line L1.

The noise suppression capacitor 13 is connected to connection points P5, P10 and the ground terminal E1. The ground terminal E1 is earthed.

The filter protection circuit 2 filters out unwanted current from the AC power supply 1 and protects the subsequent circuit. The filter protection circuit 2 is composed of a choke coil, an inrush current prevention resistor, and an NTC (Negative Temperature Coefficient) thermistor. A choke coil is an inductor that allows DC current or current (power, signal) at a frequency lower than the target frequency to pass through, while blocking current higher than the target frequency. An inrush current prevention resistor is a resistor that prevents inrush current when the power is turned on. An NTC thermistor is a thermistor with negative temperature characteristics (temperature compensation). The filter protection circuit 2 sends the current from the AC power supply 1 to the diode bridge 3.

The diode bridge 3 sends the current from the filter protection circuit 2 to the smoothing electrolytic capacitor 4. The diode bridge 3 and the smoothing electrolytic capacitor 4 perform full-wave rectification.

The transformer circuit 5 transforms the primary voltage on the input side, which is the voltage from the diode bridge 3, into the secondary voltage on the output side. The transformer circuit 5 is composed of an isolation transformer, a snubber, a power supply IC (Integrated Circuit), etc. The transformer circuit 5 obtains the voltage fluctuation status from the secondary side power supply feedback circuit 9 and controls the transformer operation based on the voltage fluctuation status to obtain a stable DC voltage. Note that the diagram of the connection lines between the transformer circuit 5 and the power supply feedback circuit 9 is omitted.

The voltage-generating diode 6 and the smoothing capacitor 7 generate a desired DC voltage (e.g., 12V) from the voltage transformed by the transformer circuit 5. The coupling capacitor 12 allows only the signal current to pass through and blocks the DC current. That is, the coupling capacitor 12 utilizes the characteristic of a capacitor to block the DC component, extracting only the AC component from the DC and AC components and allowing it to pass through. The coupling capacitor 12 removes switching noise generated on the primary side.

The power feedback circuit 9 detects the voltage on the secondary side of the transformer circuit 5 and outputs a feedback signal to the transformer circuit 5 to control the input on the primary side of the transformer circuit 5. The control circuit 8 operates using the voltage transformed by the transformer circuit 5.

The control circuit 8 is composed of a DC (Direct Current) DC converter, a microcontroller, a thermistor, a stepping motor, and the like. The control circuit 8 generates a low voltage (e.g., 5V) required in subsequent stages, controls a fan motor (not shown), a refrigerant circuit (not shown), detects temperature using a thermistor (not shown), controls airflow direction using a stepping motor (not shown), and controls the high-voltage power supply circuit 10. The high-voltage power supply circuit 10 generates a high voltage of approximately 6000V from a low voltage of approximately 10V. The high-voltage power supply circuit 10 drives the tactile device 11 with the high voltage it generates.

The noise reduction capacitors 13 and 14 discharge noise components generated on the indoor unit 100 circuit and passing through the circuit, as well as noise components introduced from the outside and passing through the circuit, to the ground via the ground terminal E1.

For example, the noise suppression capacitor 13 discharges noise (noise components) 150 that is sent via the AC power supply 1, filter protection circuit 2, diode bridge 3, connection point P1, transformer circuit 5, connection point P4, coupling capacitor 12, and connection point P5 to ground via connection point P10 and ground terminal E1.

Furthermore, the noise suppression capacitor 14 discharges the noise (noise component) 160 sent via the tactile device 11, the high-voltage power supply circuit 10, and the connection point P9 to the ground via the connection line L1, the connection point P10, and the ground terminal E1. In this way, the ground terminal E1 in Embodiment 1 is a common ground terminal for the noise suppression capacitors 13 and 14.

In the indoor unit 100, after the AC power supply 1 is turned on, the current from the AC power supply 1 is sent to the diode bridge 3 via the filter protection circuit 2. This current is full-wave rectified by the diode bridge 3 and the smoothing electrolytic capacitor 4.

The current from the AC power supply 1 is full-wave rectified, then the voltage is converted in the transformer circuit 5, and the voltage is converted to a desired DC voltage by the voltage generating diode 6 and the smoothing capacitor 7, and sent to the high-voltage power supply circuit 10. The high-voltage power supply circuit 10 generates a high voltage from the low voltage converted by the voltage generating diode 6 and the smoothing capacitor 7, and drives the tactile device 11 with the generated high voltage.

The indoor unit 100 dissipates both noise 150, which enters from the AC power supply 1 such as lightning, and noise 160, which enters from parts touched by the user (touchable devices 11) such as static electricity, to the ground via a separate path so as not to affect the control circuit 8. As a result, the indoor unit 100 is a robust air conditioner against external disturbances such as noise 150 and 160. Noise 150, which enters from the AC power supply 1 such as lightning, is the first type of noise, and noise 160, which enters from touchable devices 11 that the user touches, is the second type of noise.

Figure 4 shows the configuration of an air conditioner according to Embodiment 1. The air conditioner 500 comprises an indoor unit 100 and an outdoor unit 400. In the air conditioner 500, the indoor unit 100 and the outdoor unit 400 are connected via signal lines or the like. If the outdoor unit 400 has a ground connection, the indoor unit 100 and the outdoor unit 400 are connected via a ground cable or the like.

Here, the circuit configuration of the comparative example air conditioner will be described. Figure 5 shows the circuit configuration of the indoor unit of the comparative example air conditioner. Compared to the indoor unit 100, the indoor unit 300 of the comparative example air conditioner does not have connection points P9 and P10, and a noise suppression capacitor 14. Furthermore, the indoor unit 300 does not have a connecting wire connecting connection point P9 and the noise suppression capacitor 14, nor does it have a connecting wire L1 connecting connection point P10 and the noise suppression capacitor 14.

The operation of the indoor unit 300 in the comparative example when noise 150 and 161 are introduced into the indoor unit 300 from outside will be explained. Noise 150 introduced into the AC power supply 1 from lightning, other equipment, etc. flows towards the ground. In other words, in the indoor unit 300 of the air conditioner, similar to the indoor unit 100, the noise 150 sent via the AC power supply 1, filter protection circuit 2, diode bridge 3, connection point P1, transformer circuit 5, connection point P4, coupling capacitor 12, and connection point P5 is discharged to the ground by the noise removal capacitor 13 via connection point P10 and ground terminal E1.

Meanwhile, in the indoor unit 300, noise 161 such as static electricity introduced from the tactile device 11 is also discharged to ground via the noise-reducing capacitor 13. Specifically, in the indoor unit 300, the noise-reducing capacitor 13 discharges the noise 161 sent via the high-voltage power supply circuit 10, connection point P8, connection point P7, and connection point P5 to ground via connection point P10 and ground terminal E1.

For example, if the noise suppression capacitor 13 is located at the position shown in Figure 5, the noise 161 introduced from the tactile device 11 will pass near the control circuit 8 before flowing to ground. Therefore, in the indoor unit 300, low-voltage devices such as the microcomputer (not shown) in the control circuit 8 may malfunction or, in some cases, fail due to the influence of the noise 161.

Furthermore, if the noise suppression capacitor 13 in the indoor unit 300 is moved closer to the high-voltage power supply circuit 10, noise 150 introduced from lightning strikes in the AC power supply 1, or from other equipment, will affect the control circuit 8. In this case, low-voltage devices such as the microcomputer in the control circuit 8 of the indoor unit 300 may malfunction or, in some cases, fail due to the effects of the noise 150.

Furthermore, while the frequency components of noise 150 introduced from lightning, other equipment, etc., are low-frequency, ranging from several hundred Hz to about 1 MHz, the static electricity introduced from the tactile device 11 via the human body is high-frequency, at several hundred MHz. Therefore, if the indoor unit 300 has only one noise suppression capacitor 13, it is difficult to select a noise suppression capacitor 13 with a capacitance sufficient to adequately remove noise 150 and 161 introduced from both the power supply and the user's touch, regardless of where the noise suppression capacitor 13 is placed, making it impossible to avoid malfunctions and failures.

In the indoor unit 100, as described above, if noise 150 is introduced from lightning or other equipment, the introduced noise 150 flows from the AC power supply 1 through the noise suppression capacitor 13 towards the ground. Also, in the indoor unit 100, noise 160 such as static electricity introduced from the tangible device 11 flows through the noise suppression capacitor 14 towards the ground. Here, by making the capacitance of the noise suppression capacitor 13 larger than the capacitance of the noise suppression capacitor 14, low-frequency noise components such as lightning do not flow through the noise suppression capacitor 13 to the subsequent stage. Also, high-frequency noise components such as static electricity pass through the noise suppression capacitor 14 and do not affect the control circuit 8, etc.

As described above, the indoor unit 100 of Embodiment 1 is equipped with noise-reducing capacitors 13 and 14, so that both noise 150 such as lightning introduced from the AC power supply 1 and noise 160 such as static electricity introduced from the tactile device 11 can be discharged to ground without adversely affecting the control circuit 8. As a result, the indoor unit 100 can operate stably without the control circuit 8 malfunctioning or failing even in the face of disturbances such as noise 150 and 160.

In other words, in the indoor unit 100, the path through which noise 150 entering from the AC power supply 1 passes through the noise suppression capacitor 13 is different from the path through which noise 160 entering from the tactile device 11 passes through the noise suppression capacitor 14. Therefore, even if there is a possibility of noise 150 and 160 entering from both the AC power supply 1 and the user-touched area (tactile device 11), the control circuit 8 can be prevented from malfunctioning.

Embodiment 2.
Next, Embodiment 2 will be described using Figure 6. In Embodiment 2, the noise suppression capacitor 13 and the noise suppression capacitor 14 are connected to separate grounds.

Figure 6 shows the circuit configuration of the indoor unit of the air conditioner according to Embodiment 2. Components in Figure 6 that achieve the same function as those in the indoor unit 100 of Embodiment 1 shown in Figure 3 are denoted by the same reference numerals, and redundant explanations are omitted.

The indoor unit 200 of Embodiment 2 does not have a connection line L1 and a connection point P10, compared to the indoor unit 100 of Embodiment 1. Furthermore, in the indoor unit 200, the noise suppression capacitor 14 is connected to the ground via a different ground terminal E2 than the ground terminal E1 to which the noise suppression capacitor 13 is connected. That is, in the indoor unit 200, the noise suppression capacitor 13 is connected to the first ground terminal (first ground connection point), which is ground terminal E1, and the noise suppression capacitor 14 is connected to the second ground terminal (second ground connection point), which is ground terminal E2. Ground terminal E2 is a terminal that releases noise 170, such as static electricity, introduced from the tactile device 11 to the ground. Ground terminal E1 in Embodiment 2 is a terminal that releases noise 150, such as lightning, introduced from the AC power supply 1 to the ground.

The noise suppression capacitor 13 and the noise suppression capacitor 14 are connected to different grounds via different ground terminals. Alternatively, the noise suppression capacitors 13 and 14 may be connected to the same ground via different ground terminals. The ground (ground metal part) is a metal plate, a metal block, etc. Specifically, the ground is a housing (sheet metal case) surrounding the power supply board, which is constructed using a metal plate, or a heat exchanger, which is constructed using a metal block. When the noise suppression capacitors 13 and 14 are connected to ground via different ground terminals, one of the noise suppression capacitors 13 and 14 is connected to the housing surrounding the power supply board, and the other is connected to the heat exchanger of the indoor unit.

Thus, in Embodiment 2, the noise suppression capacitors 13 and 14 are connected to different grounds via different ground terminals. In other words, the indoor unit 200 may be configured to be grounded to separate points on the ground using separate cables, etc., rather than on the circuit.

For example, as shown in Figure 6, on the circuit board where the indoor unit 200's circuit is located, the ground terminal E1 connected to the noise suppression capacitor 13 and the ground terminal E2 connected to the noise suppression capacitor 14 are each located in different positions. Then, the ground terminals E1 and E2 are each separately connected to the ground metal part (such as the heat exchanger in the case of an air conditioner) that is connected to the ground terminal of the AC power supply 1. In other words, the wiring for dissipating the noise 150 and 170 from the noise suppression capacitors 13 and 14 is not done on the circuit board of the indoor unit 200, but by connecting each to the ground metal part with separate wiring.

Thus, in the indoor unit 200 of Embodiment 2, the ground terminal E1 connected to the noise suppression capacitor 13 and the ground terminal E2 connected to the noise suppression capacitor 14 are located in separate positions and connected to the ground metal part by separate wiring. Therefore, noise interference from the ground metal part can be prevented more effectively than in the indoor unit 100 of Embodiment 1.

The configurations shown in the above embodiments are merely examples, and can be combined with other known technologies, or the embodiments themselves can be combined. Furthermore, parts of the configuration can be omitted or modified without departing from the spirit of the invention.

1 AC power supply, 2 Filter protection circuit, 3 Diode bridge, 4 Smoothing electrolytic capacitor, 5 Transformer circuit, 6 Voltage generating diode, 7 Smoothing capacitor, 8 Control circuit, 9 Power feedback circuit, 10 High voltage power supply circuit, 11 Accessible device, 12 Coupling capacitor, 13, 14 Noise suppression capacitor, 100, 200, 300 Indoor unit, 101 Design panel, 150, 160, 161, 170 Noise, 400 Outdoor unit, 500 Air conditioner, E1, E2 Ground terminal, L1 Connection wire, P1 to P10 Connection points.

Claims (6)

Devices that users can touch,
A first noise reduction capacitor that discharges the first noise introduced from the AC power supply to ground,
A second noise suppression capacitor that discharges the second noise introduced from the aforementioned device to the ground,
Equipped with,
The path through which the first noise passes via the first noise suppression capacitor and the path through which the second noise passes via the second noise suppression capacitor are different paths.
Indoor unit. The first noise suppression capacitor and the second noise suppression capacitor are connected to a common ground terminal.
The indoor unit according to claim 1. The first noise suppression capacitor is connected to the first ground terminal, and the second noise suppression capacitor is connected to the second ground terminal.
The indoor unit according to claim 1. The capacitance of the first noise suppression capacitor is greater than the capacitance of the second noise suppression capacitor.
The indoor unit according to claim 1 . The first ground terminal and the second ground terminal are connected by separate wiring to a ground metal part located at a different position on the circuit board from where the first ground terminal and the second ground terminal are located.
The indoor unit according to claim 3. An indoor unit according to any one of claims 1 to 5,
Outdoor unit and
It had,
Air conditioner.