Electric motors and air conditioners

Abstract

This electric motor has an integrated circuit board (11) containing an inverter circuit, and the integrated circuit board (11) is integrally moulded using resin. The electric motor has a metal plate (3) that is reflow-soldered to a solid pattern of the integrated circuit board (11). The pattern to which the metal plate (3) is soldered is a high-voltage part.

Description

[Technical Field]

[0001] The present disclosure relates to an electric motor and an air conditioner. [Background technology]

[0002] In recent years, there has been a demand for higher output fan motors (electric motors for fans) in air conditioners to save energy and improve heating capacity. There is also a demand for smaller fan motors to ensure proper airflow. This has led to an issue of temperature rise on the built-in inverter board.

[0003] In Patent Document 1, heat dissipation is improved by using a heat dissipation pattern on the board.

[0004] 1 is a cross-sectional view of a conventional electric motor. The conventional electric motor includes an internal substrate 11 on which a heat dissipation substrate pattern 2A is formed, molded resin 12, a stator core 21, windings 22, a rotating shaft 31, a rotor magnet 40, and a power IC (Integrated Circuit) 80. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 077246 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology disclosed in Patent Document 1 is insufficient to meet the above requirements.

[0007] The present disclosure has been made in view of the above, and has an object to provide an electric motor that can improve heat dissipation performance. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the electric motor according to the present disclosure is a base including an inverter circuit. A board and A metal plate is soldered to the solid pattern of the board by reflow soldering, The substrate and metal plate are molded together from resin to form a molded stator. Soldering metal plates Betta The pattern is the high voltage part. The metal plate is divided into multiple parts. Solid pattern are placed. [Effects of the Invention]

[0009] The electric motor according to the present disclosure has the effect of improving heat dissipation performance. [Brief explanation of the drawings]

[0010] [Figure 1] Cross section of a conventional electric motor [Figure 2] 1 is a cross-sectional view of an electric motor according to a first embodiment; [Figure 3] 1 is a cross-sectional view of an electric motor according to a first embodiment; [Figure 4] 1 is a cross-sectional view of an electric motor according to a first embodiment; [Figure 5] 1 is a cross-sectional view of an electric motor according to a first embodiment; [Figure 6] Built-in board circuit diagram of the electric motor according to the first embodiment [Figure 7] Cross-sectional view of a built-in board of an electric motor according to the first embodiment [Figure 8] Cross-sectional view of a built-in board of an electric motor according to the first embodiment [Figure 9] Cross-sectional view of a built-in board of an electric motor according to the first embodiment [Figure 10] Cross-sectional view of a built-in board of an electric motor according to the first embodiment [Figure 11] Schematic diagram of a built-in board of an electric motor according to the first embodiment [Figure 12] 1 is a cross-sectional view of an electric motor according to a first embodiment; [Figure 13] Schematic diagram of an air conditioner according to embodiment 2 [Figure 14] FIG. 1 is a diagram showing a processor in the case where a control unit included in an electric motor according to a first embodiment is realized by the processor; [Figure 15] FIG. 1 is a diagram showing a processing circuit in the case where a control unit included in an electric motor according to a first embodiment is realized by the processing circuit; DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an electric motor and an air conditioner according to an embodiment will be described in detail with reference to the drawings.

[0012] Embodiment 1 (composition) A description will be given of an electric motor according to embodiment 1. Fig. 12 is a cross-sectional view of an electric motor 1 according to embodiment 1. This electric motor 1 is a brushless DC (Direct Current) motor. The electric motor 1 has an insulator 23 integrally molded with the stator core 21 to insulate the windings 22 from the stator core 21, which is made by laminating electromagnetic steel sheets. The windings 22 are wound around each slot of the stator core 21, which is integrally molded with the insulator 23, to form the stator 20. The windings 22 are made of copper, aluminum, or the like. The built-in substrate 11, which is equipped with a circuit including a power IC, a microcomputer, and a magnetic sensor (such as a Hall IC) that detects the position of the rotor 30, is disposed perpendicular to the axial direction of the rotating shaft 31 between the output-side bearing 33 and the stator 20, and is fixed to the insulator 23. The power IC on the built-in substrate 11 and the windings 22 are connected via winding terminals. The built-in substrate 11 is provided with a lead outlet 14 having lead wires 13 that connect to a higher-level system (for example, a board on the unit side of an air conditioner). On the built-in substrate 11, passive components such as an operational amplifier, a comparator, a regulator, a diode, a resistor, a capacitor, an inductor, and a fuse are arranged.

[0013] A power IC consists of six power transistors, a gate drive circuit, a protection circuit, etc. (It is also called an IPM: Intelligent Power Module). In some cases, the six power transistors are configured individually. In this case, the gate drive circuit may consist of a single IC, or it may consist of three ICs for each of the three phases.

[0014] The gate drive circuit and control unit may be configured in a single IC, or the control unit may be configured in a single dedicated IC (control IC) or a microcomputer.

[0015] In some cases, six power transistors, a gate drive circuit, a protection circuit, and a control unit are configured in a single IC.

[0016] Power transistors include superjunction MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), planar MOSFETs, and IGBTs (Insulated Gate Bipolar Transistors).

[0017] Since a large current flows through a power transistor, it generates a lot of heat and heat dissipation can become a problem.

[0018] In the above example, the rotor magnetic flux position is detected by a magnetic pole sensor, but in some cases the rotor magnetic pole position is estimated and controlled (sensorless control) from the current flowing through the windings 22 and the voltages applied to and generated in the windings 22. To detect the current, a shunt resistor and the signal from the current sensor may be amplified by an operational amplifier or the like. Also, a comparator may be used to generate a signal from this current signal to the control unit for overcurrent protection.

[0019] There are cases where the voltage (e.g., 15V) that drives the gate of a power transistor is different from the microcomputer power supply voltage (e.g., 5V), so in such cases a regulator is used to generate another power supply from one power supply supplied externally. For example, a 15V power supply is supplied externally, and a 5V power supply is generated by a regulator. This regulator may be built into the gate drive circuit or power IC.

[0020] There are two types of magnetic sensors 50: those with digital output signals (hereinafter referred to as Hall ICs) and those with analog signals (Hall elements). Hall ICs are further classified into the following types. The sensor and amplifier sections are composed of separate semiconductor chips, with the sensor section made of a semiconductor other than silicon and the amplifier section made of silicon (hereafter referred to as a non-silicon Hall IC). The sensor and amplifier are composed of a single silicon semiconductor chip. Non-silicon Hall ICs have two built-in chips, so the center of the sensor is positioned at a different location from the center of the IC body. The sensor part of a non-silicon Hall IC uses semiconductors such as indium antimonide (InSb). Compared to silicon semiconductors, these non-silicon semiconductors have advantages such as improved sensitivity and smaller offset due to stress distortion.

[0021] There is also a case of sensorless control where there is no magnetic sensor 50. In this case, the magnetic pole position is estimated from the current value detected by a current detection resistor or a current detection transformer, and control is performed. If necessary, the signal detected by the current detection resistor or current detection transformer may be amplified using an operational amplifier, etc.

[0022] The overcurrent detection unit monitors the voltage of the overcurrent detection resistor and achieves overcurrent protection by turning off the power transistor when the voltage exceeds a certain level. The overcurrent detection unit may be built into the control unit or into the gate drive circuit.

[0023] Brushless DC motors generate rotational power by switching the six power transistors (in the case of three phases) in the power IC at the appropriate timing according to the magnetic pole position of the rotor magnet. This switching signal is generated by the control unit. The operating principle is shown below. The magnetic pole position of the rotor 30 is estimated from the magnetic sensor 50 or the current value. The power transistors are switched on and off in response to the magnetic pole position of the rotor 30 and a speed command signal output from the system (for example, the board on the unit side).

[0024] The overcurrent detection unit (control unit or inside the power IC) achieves overcurrent protection by forcibly turning off the power transistor when the voltage across the overcurrent detection resistor exceeds a certain voltage. It also achieves overheat protection by forcibly turning off the power transistor upon receiving a signal from the temperature sensor.

[0025] There are three types of energization methods: 120° energization, 150° energization, and sine wave energization.

[0026] The molded stator 10 is formed by integrally molding the stator 20 and the built-in substrate 11, and is provided with a recess formed therein that can accommodate the rotor 30. Alternatively, the stator 20 and the built-in substrate 11 may be molded separately as an integral unit.

[0027] A metal plate is attached by solder to the heat dissipation pattern (solid pattern) that is connected to the heat dissipation tab of a power transistor, IPM, or power IC (hereafter referred to as power transistor, etc.). Metal plates can be mounted automatically by reflow soldering like other surface-mounted components, so they can be attached at low processing costs. The metal plate may be made of a non-solderable metal such as aluminum. To make it solderable, it may be coated with plating or other materials. If the metal plate is aluminum, it is plated with nickel (Ni) and tin (Sn). Furthermore, if the metal plate is made of a non-solderable metal, the soldering parts of the metal plate may be plated or coated to make them solderable.

[0028] By placing a metal plate, the metal plate acts as a heat sink, widely diffusing heat and improving heat dissipation. The larger the volume of the metal plate, the better the heat dissipation.

[0029] Heat dissipation is improved if the metal plate is placed on the side of the board opposite the stator, but there are cases where power transistors and other components must be placed on the stator side due to constraints such as board area. In such cases, the pattern connected to the heat dissipation tab is connected via a through hole to the heat dissipation pattern to which the metal plate is soldered.

[0030] Some power transistors do not have a heat dissipation tab. In that case, a heat dissipation pattern is provided on the bottom of the package, which becomes hot, and a metal plate is soldered to the heat dissipation pattern connected to it.

[0031] The metal plate may be divided into multiple pieces and placed. Dividing the metal plate into pieces may result in better molding than placing a large metal plate, as it creates paths for the resin to pass through during integral molding. Furthermore, dividing the metal plate creates areas with thick and thin resin on the upper part of the built-in substrate 11, minimizing the deterioration of heat dissipation performance and improving the fluidity during resin molding, thereby improving productivity.

[0032] The metal plate may be shaped so that the cross-sectional area of ​​the part away from the board is larger than the cross-sectional area of ​​the soldered part. In this case, the metal plate and the different voltage pattern are close to each other, but because the board is integrally molded with resin, the metal plate and the different voltage pattern are insulated by the resin. With this shape, a metal plate with a larger volume can be placed within the board area and height restrictions, further improving heat dissipation.

[0033] A heat sink may be mounted on the opposite side of the board from the stator. The heat sink is integrally molded from resin. In this case, resin is placed between the metal plate and the heat sink to maintain insulation between the heat sink (metal, for example, aluminum) and the metal plate.

[0034] The heat sink may not be integrally molded, but may be attached to the molded stator 10 via a heat dissipation sheet or heat dissipation silicone.

[0035] The rotor 30 has a magnet consisting of a permanent magnet that is placed inside the molded stator 10 and on the outer periphery of the rotating shaft 31, facing the stator core 21. The magnet is made by injection molding a bonded magnet made by mixing a ferrite magnet or a rare earth magnet (samarium iron nitrogen, neodymium, etc.) with a thermoplastic resin material. The magnet is incorporated into the injection molding die, and molding is performed while applying orientation.

[0036] The outer diameter of the magnet on the magnetic sensor 50 side of the built-in substrate 11 (sensor magnet portion) is smaller than the outer diameter of the other portion (main magnet portion), making it easier for magnetic flux to flow into the magnetic sensor 50 mounted on the built-in substrate 11. In order to minimize the influence of the magnetic flux generated from the windings 22 of the stator 20, the magnetic sensor 50 is placed at a position far from the windings 22, that is, at a position close to the rotating shaft 31.

[0037] In the drawing, the main magnet portion and the sensor magnet portion are configured as one magnet, but they may be configured as separate magnets.

[0038] An output side bearing 33 that rotatably supports one end of the rotary shaft 31 is provided, and a non-output side bearing 34 that rotatably supports the other end of the rotary shaft 31 is provided.

[0039] The conductive bracket is fitted into the inner periphery of the molded stator 10 so as to close the opening of the recess in the molded stator 10, and the outer ring of the non-output side bearing 34 is fitted inside.

[0040] FIG. 12 also shows the mold resin 12, the rotor insulating portion 32, the rotor magnet 40, the bracket 60, and the press-fit portion 61.

[0041] Fig. 2 is a cross-sectional view of the electric motor according to embodiment 1. The electric motor shown in Fig. 2 has an internal substrate 11 on which a heat dissipation substrate pattern 2A is formed, molded resin 12, a stator core 21, windings 22, a rotating shaft 31, a rotor magnet 40, a power IC 80, and a metal plate 3.

[0042] Fig. 3 is a cross-sectional view of the electric motor according to embodiment 1. The electric motor shown in Fig. 3 has an internal substrate 11 on which a heat dissipation substrate pattern 2A is formed, molded resin 12, a stator core 21, windings 22, a rotating shaft 31, a rotor magnet 40, a power IC 80, and a metal plate 3. Fig. 3 also shows the path of the resin.

[0043] Figure 4 is a cross-sectional view of the electric motor according to embodiment 1. The electric motor shown in Figure 4 has an internal substrate 11 on which a heat dissipation substrate pattern 2A is formed, molded resin 12, a stator core 21, windings 22, a rotating shaft 31, a rotor magnet 40, a power IC 80, a metal plate (variation 1) 3A, and a substrate pattern 2. Figure 4 also shows the phrase "It is close to other patterns of different voltages, but it is OK because there is resin."

[0044] Figure 5 is a cross-sectional view of the electric motor according to embodiment 1. The electric motor shown in Figure 5 has an internal substrate 11 on which a heat dissipation substrate pattern 2A is formed, molded resin 12, a stator core 21, windings 22, a rotating shaft 31, a rotor magnet 40, a power IC 80, a metal plate 3, and a heat sink 6. Figure 5 also shows the phrase "resin is provided between the heat sink (metal) and the metal plate for insulation."

[0045] FIG. 6 is a circuit diagram of an internal circuit board of the electric motor according to the first embodiment. Shown in FIG. 6 are a control unit 70 connected to ground 79, a power IC 80 connected to the control unit 70, a winding 22 connected to the power IC 80, a magnetic sensor 50, an overcurrent detection resistor 75 connected to the control unit 70 and the power IC 80 at one end and to ground 79 at the other end, a high-voltage power supply 77, and a low-voltage power supply 78. The control unit 70 receives a speed command signal (from the system to the motor) and transmits a rotation speed signal (from the motor to the system). The control unit 70 is connected to the low-voltage power supply 78. The power IC 80 has a power transistor 81, a gate drive circuit 82, and a protection circuit 83. The gate drive circuit 82 is connected to the control unit 70, the high-voltage power supply 77, the low-voltage power supply 78, ground 79, and the power transistor 81. One end of the protection circuit 83 is connected to the gate drive circuit 82, another end of the protection circuit 83 is connected to ground 79, and yet another end of the protection circuit 83 is connected to a wiring connecting the control unit 70 and the overcurrent detection resistor 75. An overcurrent detection signal flows through the wiring connecting the control unit 70 and the overcurrent detection resistor 75. The power transistors 81 include a U-phase upper-arm power transistor 81A, a V-phase upper-arm power transistor 81B, a W-phase upper-arm power transistor 81C, a U-phase lower-arm power transistor 81D, a V-phase lower-arm power transistor 81E, and a W-phase lower-arm power transistor 81F. FIG. 6 also shows "U" representing the U phase, "V" representing the V phase, and "W" representing the W phase. The winding 22 includes a U-phase winding 22U, a V-phase winding 22V, and a W-phase winding 22W.

[0046] FIG. 7 is a cross-sectional view of a built-in substrate of the electric motor according to the first embodiment. Regarding the built-in substrate 11 shown in FIG. 7, a heat dissipation substrate pattern 2A is formed on each of two flat surfaces of the built-in substrate 11. A plurality of through holes 4 are formed inside the built-in substrate 11. A metal plate 3 is disposed on one flat surface of the built-in substrate 11. A power transistor 81 and a heat dissipation tab terminal 81T are disposed on the other flat surface of the built-in substrate 11. The heat dissipation tab terminal 81T is in contact with the heat dissipation substrate pattern 2A on the other flat surface of the built-in substrate 11. A portion of the power transistor 81 is located on the flat surface of the heat dissipation tab terminal 81T that is not on the built-in substrate 11 side. Another portion of the power transistor 81 is in contact with the other flat surface of the built-in substrate 11 and the heat dissipation substrate pattern 2A on the other flat surface of the built-in substrate 11.

[0047] Fig. 8 is a cross-sectional view of a built-in substrate of the electric motor according to embodiment 1. With respect to the built-in substrate 11 shown in Fig. 8, a heat dissipation substrate pattern 2A is formed on each of two flat surfaces of the built-in substrate 11. A plurality of through holes 4 are formed inside the built-in substrate 11. A metal plate 3 is disposed on one flat surface of the built-in substrate 11. A power IC (without a heat dissipation tab) 80A is disposed on the other flat surface of the built-in substrate 11.

[0048] Fig. 9 is a cross-sectional view of a built-in substrate of the electric motor according to the first embodiment. With respect to the built-in substrate 11 shown in Fig. 9, a heat dissipation substrate pattern 2A is formed on one of the two flat surfaces of the built-in substrate 11. A metal plate 3, a power transistor 81, and a heat dissipation tab terminal 81T are arranged on the heat dissipation substrate pattern 2A. A part of the power transistor 81 is located on one of the two flat surfaces of the heat dissipation tab terminal 81T that is not on the side of the heat dissipation substrate pattern 2A. Another part of the power transistor 81 is in contact with one of the two flat surfaces of the built-in substrate 11 and the heat dissipation substrate pattern 2A.

[0049] Fig. 10 is a cross-sectional view of a built-in substrate of the electric motor according to embodiment 1. With respect to built-in substrate 11 shown in Fig. 10, a heat dissipation substrate pattern 2A is formed on one of the two flat surfaces of built-in substrate 11. A metal plate 3 and a power IC (without a heat dissipation tab) 80A are arranged on heat dissipation substrate pattern 2A.

[0050] 11 is a schematic diagram of a built-in substrate of an electric motor according to embodiment 1. In the built-in substrate 11 shown in FIG. 11, a rotary shaft through-hole 35 is formed in the center of the disk-shaped built-in substrate 11. A metal plate soldering portion 5 to which a metal plate (variation 1) 3A is attached is located on one of the two flat surfaces of the built-in substrate 11. The metal plate (variation 1) 3A is attached to the metal plate soldering portion 5.

[0051] The electric motor according to the first embodiment will be further described below. The electric motor according to the first embodiment has a built-in substrate including an inverter circuit, and the substrate is integrally molded from resin. The electric motor according to the first embodiment has a metal plate soldered to a solid pattern on the substrate by reflow soldering. The pattern to which the metal plate is soldered is a high-voltage section. The electric motor according to the first embodiment can improve heat dissipation performance. The metal plate can be soldered by reflow soldering in the same way as other surface-mounted components, so the processing costs for the electric motor according to the first embodiment are low. Although the metal plate is treated as a high-voltage plate, there is no problem with insulation distance because it is molded with resin.

[0052] Embodiment 2 (composition) An air conditioner according to a second embodiment will be described. The air conditioner comprises an indoor unit and an outdoor unit connected to the indoor unit. The indoor unit is equipped with an indoor unit blower, and the outdoor unit is equipped with an outdoor unit blower. The outdoor unit blower and the indoor unit blower each incorporate the electric motor described in embodiment 1 as a drive source. In other words, the air conditioner according to embodiment 2 is equipped with the electric motor described in embodiment 1.

[0053] In particular, commercial air conditioners are required to have higher output and therefore high heat dissipation performance, so the air conditioner according to the second embodiment is highly effective.

[0054] 13 is a schematic diagram of an air conditioner 200 according to embodiment 2. The air conditioner 200 has an indoor unit 210 equipped with an electric motor 1 and an indoor unit board 211, and an outdoor unit 220 equipped with an outdoor unit blower 223.

[0055] In addition to air conditioners, the electric motor can also be mounted and used in, for example, ventilation fans, home appliances, machine tools, etc.

[0056] Fig. 14 is a diagram showing a processor 91 when the control unit 70 of the electric motor according to the first embodiment is realized by the processor 91. That is, the functions of the control unit 70 may be realized by the processor 91 that executes a program stored in a memory 92. The processor 91 is a CPU (Central Processing Unit), a processing device, an arithmetic unit, a microprocessor, or a DSP (Digital Signal Processor). The memory 92 is also shown in Fig. 14.

[0057] When the functions of the control unit 70 are realized by the processor 91, the functions are realized by the processor 91 together with software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 92. The processor 91 realizes the functions of the control unit 70 by reading and executing the program stored in the memory 92.

[0058] When the functions of the control unit 70 are realized by the processor 91, the electric motor has a memory 92 for storing a program that results in the execution of steps performed by the control unit 70. It can also be said that the program stored in the memory 92 causes the computer to execute the control unit 70.

[0059] The memory 92 may be, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), 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 Disk).

[0060] 15 is a diagram illustrating a processing circuit 93 in a case where the control unit 70 included in the electric motor according to the first embodiment is realized by the processing circuit 93. In other words, the control unit 70 may be realized by the processing circuit 93.

[0061] The processing circuit 93 is dedicated hardware. The processing circuit 93 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. A part of the control unit 70 may be realized by dedicated hardware separate from the rest.

[0062] Some of the functions of the control unit 70 may be implemented by software or firmware, and the remaining functions may be implemented by dedicated hardware. In this way, the functions of the control unit 70 can be implemented by hardware, software, firmware, or a combination thereof.

[0063] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other, or part of the configuration may be omitted or modified within the scope of the gist of the invention. [Explanation of symbols]

[0064] 1 electric motor (motor), 2 board pattern, 2A heat dissipation board pattern, 3 metal plate, 3A metal plate (variant 1), 4 through hole, 5 metal plate soldering portion, 6 heat sink, 10 molded stator, 11 built-in board, 12 molded resin, 13 lead wire, 14 lead outlet portion, 20 stator, 21 stator core, 22 winding, 22U U-phase winding, 22V V-phase winding, 22W W-phase winding, 23 insulator, 30 rotor, 31 rotating shaft, 32 rotor insulation portion, 33 output side bearing, 34 anti-output side bearing, 35 rotating shaft through hole, 40 rotor magnet, 50 magnetic sensor, 60 bracket, 61 press-fit portion, 70 control portion, 75 overcurrent detection resistor, 77 high-voltage power supply, 78 low-voltage power supply, 79 ground, 80 Power IC, 80A power IC (without heat dissipation tab), 81 power transistor, 81A U-phase upper arm power transistor, 81B V-phase upper arm power transistor, 81C W-phase upper arm power transistor, 81D U-phase lower arm power transistor, 81E V-phase lower arm power transistor, 81F W-phase lower arm power transistor, 81T heat dissipation tab terminal, 82 gate drive circuit, 83 protection circuit, etc., 91 processor, 92 memory, 93 processing circuit, 200 air conditioner (air conditioner), 210 indoor unit, 211 indoor unit board, 220 outdoor unit, 223 outdoor unit blower.

Claims

1. a substrate including an inverter circuit; a metal plate soldered to the solid pattern of the substrate by reflow soldering; The substrate and the metal plate are integrally molded from resin to form a molded stator, the solid pattern to which the metal plate is soldered is a high voltage portion, The metal plate is divided into a plurality of pieces and arranged in the solid pattern. Electric motor.

2. The cross-sectional area of ​​the metal plate at a portion away from the substrate is larger than the cross-sectional area of ​​the soldered portion.

2. The electric motor according to claim 1.

3. The metal plate is made of a non-solderable metal, and the soldering portion of the metal plate is plated and coated so as to be solderable.

3. The electric motor according to claim 1 or 2.

4. An air conditioner equipped with the electric motor according to any one of claims 1 to 3.

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