Noise reduction system for mechanical switch

Abstract

A noise reduction system for mechanical switch, wherein it consists of alternating current (AC) power, a voltage level detector circuit, a memory, a microcontroller, a relay driver circuit, a relay and an electric valve. The AC power is connected with the voltage level detector circuit, which lowers the voltage prior to signalling to the microcontroller. The microcontroller analyses to locate zero cross signal of the AC power. The operation starts from the AC power in the form of electrical signal wave in a condition where voltage levels are in the form of sine wave, and then the voltage is lowered prior to signalling to be processes together with contact relay's time delay (td). The memory functions in storing the contact relay's time delay (td). Afterwards, the relay driver circuit receives an instruction to turn on signal from the microcontroller and then increase voltage levels for stable operation of the relay. The contact relay's time delay (td) makes connection at a low-voltage point of the AC power and then connects-disconnects electric current from the AC power to the electric valve, causing a voltage drop at coil of the electric valve and output voltage from device. The electric valve functions in controlling the direction of flow of a coolant inside an air conditioner. Therefore, the noise reduction for mechanical switch by controlling the operational rhythms of the contact relay that connects the circuit in a condition where the sine wave is at low voltage levels results in minimised noises and helps prolong the contact relay's useful life.

Description

[0001] NOISE REDUCTION SYSTEM FOR MECHANICAL SWITCH

[0002] Field of the Invention

[0003] Engineering relating to noise reduction systems for mechanical switches.

[0004] Background of the Invention

[0005] In general, an air conditioner contains integrated circuits functioning to control the operation of various devices, such as an electric valve controlling a coolant’s direction of flow.

[0006] The operational principle of an electric valve controlling a coolant’s direction of flow is based on the principle of a solenoid valve. Power supply to a solenoid valve’s electromagnetic coil induces a magnetic field inside the coil that will attract the magnet inside the valve to move in order to close or open a passage of the valve, resulting in a coolant’s direction of flow being controlled as desired.

[0007] The operation of an electric valve controlling a coolant’s direction of flow is, in turn, controlled by an electronic device, such as a relay, transistor or microcontroller. These devices function to receive signals from a cooling system controller prior to signalling in order to activate the operation of a solenoid valve.

[0008] Electric valves controlling coolants’ direction of flow are used in cooling and air- conditioning systems, such as air conditioners, etc. This type of valves is important for cooling systems’ operation because they optimise coolant’ direction of flow according to conditions of use.

[0009] A relay is an electronic device functioning as a disconnecting switch, using electromagnetic wave. A relay is operational upon relay of voltage to an electromagnetic coil, generating a magnetic field inside the coil, attracting the magnet inside the relay to move in order to close or open relay’s contacts and resulting in an electrical circuit being connected or disconnected in a desired direction.

[0010] As the operational principle of a relay, power supply to an electromagnetic coil will induce a magnetic field inside the coil that attract magnet inside the relay to move in order to close or open relay’s contacts, resulting in an electrical circuit being connected or disconnected in a desired direction.

[0011] A relay’s electric conductor contacts are the relay’s components functioning as an electric conductor for use in electrical circuit connection or disconnection. Such contacts are usually made from conductive materials, such as silver or copper, and can be divided into 2 main types, namely normally open relays with open contacts when relays are inactive and normally closed relays with closed contacts when relays are inactive.

[0012] Connecting and disconnecting method of alternating current (AC) power to an electric valve’s coil is enabled by use of a device called a power relay. However, as voltage levels of AC power are dependent on sine wave, the connection of an electrical circuit using a relay, which relies on electric conductor contacts of the relay in the connection, is likely to occur in a condition of low voltage levels or of high voltage levels of since wave. Should electric conductor contacts connect a circuit at high voltage levels of sine wave, noise will be large. Noises result in electrical circuit malfunction, shortening the useful life of a relay’s electric conductor contacts. Electric conductor contacts are, therefore, opted to connect a circuit at low voltage levels of sine wave instead, and noises are minimised.

[0013] A zero cross signal is a signal at the point of intersection at zero of constant amplitude axis. The said signal is used for directional purpose of alternating current (AC) signals or is the point where sine wave signal equals zero, occurring when the sine wave signal switches from positive electrode to negative one or vice versa. The zero cross signal is alternatively called zero crossing.

[0014] In an electrical circuit, sine wave signal is usually used as signal that controls the operation of various devices, such as a motor or other electrical appliances. Zero cross signal is the optimal point in alternating these devices because the signal immediately switches between electrodes, resulting in fast and accurate operation of devices.

[0015] After performing Thai and International patent database searches, sone prior inventions relating to noise reduction systems for mechanical switches were found. For example:

[0016] A Japanese patent, publication number JP1991055455A, with the invention title ‘Noise filter for air conditioner’ has mentioned a process that occurs upon piloting signal being transmitted from a control circuit; that is, the first contact is closed. Following a short duration, the second contact is closed. This leads to sufficient electric correct through a four-way valve coil that operates with direct current. Afterwards, upon contacts being open following the elapsed time, the said coil gains energy through resistance so that the used electric current is limited. Part of noises induced by an inverter circuit is, therefore, adsorbed by capacity (EC) of variable DC / DC power supply and four-way valve coil that operates with direct current. Remaining noises and noises induced by a rectifier are reduced by an alternating current noise filter. In addition, alternating and direct currents do not co-exist around the control circuit, resulting in lower tolerance to overall noises. Also, a European patent, publication number EP31404512A1, with the invention tile ‘Power conversion device and air conditioning device’ has mentioned a power conversion device for use in an air conditioner’s outdoor unit. The device consists of 1. an alternating-to-direct current converter, functioning to convert the alternating voltage from AC power to direct current; 2. a voltage generator used wit a compressor-driving part operating with a compressor; 3. a direct voltage regulator that regulates direct voltage output from the said converter; 4. a first noise reducer with inductive reactance, an end connected with the AC power and the other end connected with the said converter; 5. a second noise reducer with capacitive and removed reactance between the first noise reducer and the said converter; 6. an influx-blocking circuit connected in parallel with the second noise reducer and the said converter to block the influx through the said regulator; 7. a first AC power relay, which opens and closes an AC power path to the said blocking circuit; and 8. a second AC power relay, which opens and closes an AC power path to the second noise reducer.

[0017] It can be seen that the prior inventions have claimed noise reduction methods in air conditioners. Both patents use similar basic electronic devices, such as relays, resister and capacitor, wherein the purpose are similar to this invention.

[0018] The noise reduction system for mechanical switch, however, controls operational rhythms of electronic conductor contacts of a relay that connects a circuit in a condition where sine wave is at low voltage levels. This requires a microcontroller that is aware of the condition of AC power, and contains a part that detects and lowers the power supply’s voltage levels prior to proceeding to send it to the microcontroller. Afterwards, the microcontroller analyses for zero cross signal from the AC power. The operation starts from the AC power in the form of electrical signal wave in a condition where voltage levels are in the form of sine wave, and then the voltage is lowered prior to signalling for processing together with a contact relay’s time delay (td) prior to sending an instruction for the relay to operate. Voltage levels of signals transmitted from the microcontroller are insufficient for direct transmission to the relay’s coil, hence a relay driver circuit. The operation starts from the microcontroller by sending an instruction to turn on signal for the relay driver circuit. Afterwards, the contact relay's time delay (td) makes the connection at a low-voltage point of the AC power and then delivers to an electric valve, causing a voltage drop at the coil of the electric valve and output voltage from device. The electric valve functions in controlling a coolant’s direction of flow inside an air conditioner. Summary of the Invention

[0019] This invention relates to the noise reduction system for mechanical switch. The AC power is connected with a voltage level detector circuit for lowering the voltage prior to signaling to the microcontroller in order that the microcontroller analyses to locate the zero cross signal of the AC power The operation starts from the AC power in the form of the electrical signal wave in the condition where voltage levels are in the form of sine wave, and then the voltage is lowered prior to signalling and processing together with the contact relay’s time delay (td). A memory functions in storing the contact relay’s time delay (td). Afterwards, the relay driver circuit receives an instruction to turn on signal from the microcontroller and then increase voltage levels so that the relay’s operation is stable. The contact relay’s time delay (td) makes the connection at low- voltage point of the AC power. Only then does the connection and disconnection from the AC power to the electric valve begin, causing a voltage drop at the coil of the electric valve and output voltage from the device. The electric valve functions in controlling the direction of flow of the coolant inside the air conditioner.

[0020] This invention purposely controls operational rhythms of the relay’s electric conductor contacts for the electrical circuit connection a low voltage levels of sine wave, resulting in minimised noises compared with uncontrolled operation.

[0021] Brief Description of the Drawings

[0022] Figure 1 displays an embodiment of the noise reduction system for mechanical switch

[0023] Figure 2 displays an embodiment of a diagram relating to the noise reduction system for mechanical switch.

[0024] Figure 3 displays an embodiment of the operation inside the microcontroller relating to the noise reduction system for mechanical switch.

[0025] Detailed Description of the Invention

[0026] Figure 1 displays an embodiment of the noise reduction system for mechanical switch, wherein it consists of the AC power, voltage level detector circuit, memory, microcontroller, relay driver circuit, relay and elective valve. Figure 2 displays an embodiment of a diagram relating to the noise reduction for mechanical switch, and figure 3 displays an embodiment of the operation inside the microcontroller relating to the noise reduction system for mechanical switch. The AC power 1 is connected with the voltage level detector circuit 2 for detecting the power’ s voltage levels. Following the power’s voltage level detection, the voltage is lowered prior to signalling to the microcontroller 4.

[0027] Afterwards, the microcontroller 4 proceeds to analyse and locate the zero cross signal of the AC power 9. The operation starts from the AC power in the form of the electrical signal wave 8 in the condition where voltage levels are in the form of sine wave. Afterwards, the voltage is lowered prior to signalling to be processed together with the contact relay’s time delay (td) 1 Iprior to proceeding to send an instruction for the relay 6 to operate. The memory 3 function in storing a data set and an instruction set for the operation of the microcontroller 4. The stored data and instruction sets are the contact relay’s time delay (td) 11.

[0028] Voltage levels of signal transmitted from the microcontroller 4 are insufficient for direct transmission to the coil of the relay 6, hence the relay driver circuit 5, which functions to receive signals from the microcontroller 4 and then increases voltage levels for stable operation of the relay 6. The operation starts from the microcontroller (4) by sending an instruction to turn on signal 10 for the relay driver circuit 5. Afterwards, the contact relay’s time delay (td) 11 makes the connection at low-voltage point of the AC power 1 and then proceeds to connect-disconnect electric current from the AC power 1 to the electric valve 7, causing a voltage drop at the coil of the electric valve 7 and output voltage from the device 12. The electric valve 7 controls the direction of flow of the coolant inside the air conditioner.

[0029] The contact relay’s time delay (td) 11 connects circuit at low voltage levels, resulting in minimised noise. In the event that the contact relay’s time delay (td) 11 connects circuit at high voltage levels, noise are increased because of discontinues electric current flow or high electric current spark for a moment.

[0030] The sine wave signal for analysing and locating the zero crossing of the AC power 9 starts the operation from the AC power in the form of electrical signal wave 8 in the condition where voltage levels are in the form of sine wave. Afterwards, the voltage is lowered prior to signalling to the microcontroller 4 in order to analyse and locate the zero cross signal of the AC power 9.

[0031] Therein, the zero cross signal of the AC power 9 equals zero, where timing of the zero cross signal of the AC power 9 at a first position = tO, and timing of the zero cross signal of the AC power 9 at a second position = tl, respectively. With the complete two positions of the zero cross signal of the AC power 9 (tO and tl), the microcontroller 4 calculates and determines timing (t). Timing (t) = timing of the zero cross signal of the AC power 9 at the second position (tl) - timing of the zero cross signal of the AC power 9 at the first position (tO). Then, a calculated timing (tx) is determined. Calculated timing (tx) = timing (t) - the contact relay’s time delay (td); or calculated timing (tx) = timing of the zero cross signal of the AC power 9 at the second position (tl) - timing of the zero cross signal of the AC power 9 at the first position (tO) - the contact relay’s time delay (td) 11.

[0032] Upon the complete calculated timing (tx), the microcontroller 4 is allowed to use the zero cross signal of the AC power 9 at the second position (tl) as a reference zero cross signal and count time until the calculated timing (tx) is up. Afterwards, the microcontroller 4 proceeds to send an instruction to turn on signal 10 for the relay driver circuit 5. However, because of the contact relay’s time delay (td) 11, the contact relay’s time delay (td) 11 cannot immediately make the connection. Rather, the contact relay’s time delay (td) 11 will make the connection in the zero cross signal of the AC power 9 at a third position (t2).

[0033] The contact relay’s time delay (td) 11 makes the connection at low voltage, which makes the AC power 1 connect with the electric valve 7, causing a voltage drop at the coil of the electric valve 7 and output voltage from the device 12. It can be seen that the contact relay’s time delay (td) 11 relates to the connection as regards the zero cross signal of the AC power 9 at the third position (t2), which is the point where the AC power in the form of the electrical signal wave 8 has nearly zero voltage level.

[0034] Any modifications according to this invention may be clearly understood and doable by those skilled in the art. These may fall under the scope and intention of this invention as presented in the appended claims.

[0035] Best Mode of the Invention

[0036] Same as that mentioned under the Detailed Description of the Invention section.

Claims

Claims1. A noise reduction system for mechanical switch, controlling operational rhythms of a contact relay that connects a circuit in a condition with low-voltage level sine wave, wherein it consists of alternating current (AC) power (1), a voltage level detector circuit (2), a memory (3), a microcontroller (4), a relay driver circuit (5), a relay (6) and an electric valve (7), wherein it is characterized in that the AC power (1) is connected with the voltage level detector circuit (2) to detect the power’s voltage levels, following the power’s voltage level detection, the voltage is lowered prior to signalling to the microcontroller (4); afterwards, the microcontroller (4) proceeds to analyse and locate zero cross signal of the AC power (9), the operation starts from the AC power in the form of electrical signal wave (8) in a condition where voltage levels are in the form of sine wave, afterwards, the voltage is lowered prior to signalling to be processed together with contact relay’s time delay (td) (11) prior to sending an instruction for the relay (6) to operate, the memory (3) functions in storing a data set and an instruction set used for the operation of the microcontroller (4), the stored data and instruction sets are the contact relay’s time delay (td) (11); voltage levels of signals transmitted from the microcontroller (4) are insufficient for direct transmission to coil of the relay (6), hence the relay driver circuit (5), which functions in receiving signals from the microcontroller (4) and then increasing the voltage levels for stable operation of the relay (5), the operation starts from the microcontroller (4) by sending an instruction to turn on signal (10) for the relay driver circuit (5), afterwards, the contact relay’s time delay (td) (11) makes connection at a low-voltage level point of the AC power (1) and then connects-disconnects electric current from the AC power (1) to the electric valve (7), causing a voltage drop at the coil of the electric valve (7) and output voltage from device (12), the electric valve (7) controls the direction of flow of a coolant inside an air conditioner.

2. The noise reduction system for mechanical switch according to claim 1, wherein the contact relay’s time delay (td) (11) connects circuit at low voltage levels, resulting in minimized noise, in the event that the contact relay’s time delay (td) 11 connects circuit at high voltage levels, noise are increased because of discontinues electric current flow or high electric current spark for a moment.

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