Work machine

Abstract

Provided is a work machine in which a substrate that comprises a plurality of relays for switching between a delta connection and a star connection is disposed at a suitable location. A stator substrate 27 comprises: relays RY1–RY3 that turn on if a stator coil connection is a delta connection; and relays RY4, RY5 that turn on if the stator coil connection is a star connection. The stator substrate 27 is disposed at one end section of the stator in a motor shaft direction. A U-phase power source line connection section 67U, a V-phase power source line connection section 67V, and a W-phase power source line connection section 67W are disposed with mutual separation in a motor circumferential direction. The relay RY1 is located between the U-phase power source line connection section 67U and the V-phase power source line connection section 67V; the relays RY2, RY4 are located between the V-phase power source line connection section 67V and the W-phase power source line connection section 67W; and the relays RY3, RY5 are located between the W-phase power source line connection section 67W and the U-phase power source line connection section 67U.

Description

Work equipment

[0001] The present invention relates to a work machine.

[0002] Patent Document 1 discloses a power tool as a work machine in which the motor winding connection method can be switched between series connection and parallel connection depending on the type of power source (power source voltage) connected. Patent Document 1 also discloses that a circuit board equipped with a relay for switching the connection method is attached to the end of the motor (end of the stator).

[0003] Japanese Patent Application Laid-Open No. 2017-121158

[0004] The present inventors recognized that there are the following problems to be solved when introducing connection switching technology that enables the winding connection method to be switched between delta connection and star connection into a work machine. - Problem 1: To provide a work machine in which a circuit board on which multiple relays that switch between delta connection and star connection are mounted is located in an appropriate position. - Problem 2: To provide a work machine that can be easily assembled even when a circuit board on which multiple relays that switch between delta connection and star connection are mounted is mounted at the end of the stator. - Problem 3: To provide a work machine that is configured to withstand large currents while having multiple relays that switch between delta connection and star connection mounted on the circuit board. - Problem 4: To provide a work machine that is not too large.

[0005] The present invention aims to solve at least one of the above problems 1 to 4.

[0006] One aspect of the present invention is a work machine including a motor having a stator including a plurality of windings, a plurality of relays capable of switching the connection method of the plurality of windings between a delta connection and a star connection, and a first circuit board carrying the plurality of relays, the first circuit board being disposed at one end of the stator in the axial direction of the motor.

[0007] Another aspect of the present invention is a work machine including a motor having a stator including a plurality of windings, a plurality of relays capable of switching a connection method of the plurality of windings between a delta connection and a star connection, and a first board carrying the plurality of relays, wherein the plurality of relays include three first relays that are turned on when the connection method is a delta connection and two second relays that are turned on when the connection method is a star connection, the coils of the three first relays are connected in series to each other, the coils of the two second relays are connected in series to each other, a first step-down circuit that steps down an externally supplied power supply voltage and supplies the voltage to each coil of the plurality of first relays, and a second step-down circuit that steps down the power supply voltage and supplies the voltage to each coil of the plurality of second relays, the second step-down circuit having a step-down rate higher than that of the first step-down circuit.

[0008] The present invention may be expressed as an "electric working machine," "electric tool," "electrical equipment," etc., and such expressions are also valid as aspects of the present invention.

[0009] According to the present invention, at least one of the above problems 1 to 4 can be solved.

[0010] 7A and 7B are left side views of a part of the work machine 1 according to the first embodiment of the present invention. (A) is a cross-sectional view taken along line A-A in FIG. 1 . (B) is an enlarged view of part B in FIG. 2A . A perspective view of the motor 30 and its peripheral components in the work machine 1. A top view of the motor 30 and its peripheral components. A top cross-sectional view of the motor 30 and its peripheral components. A view of the stator board 27 of the work machine 1 as seen from the left. A circuit block diagram of the work machine 1. (A) is a circuit diagram of the motor connection circuit 46 in FIG. 7 . (B) is a circuit diagram showing the motor connection circuit 46 in FIG. 7 divided into the stator 45 side and the stator board 27 side. An explanatory diagram of the winding process of the stator 45. A circuit diagram showing the current supply circuits to the coils of the relays RY1 to RY5 shown in FIG. 8 and the connection relationships between the first conductive pattern 91 to the sixth conductive pattern 96 on the stator board 27. A component layout diagram on the left side of the stator board 27. 10 is a simplified circuit block diagram of the work machine 1 when the 36V step-down circuit 82 and the 24V step-down circuit 83 shown in FIG. 10 are provided on the inverter board 23 in the first embodiment. 11 is a simplified circuit block diagram of the work machine 1 when the 36V step-down circuit 82 and the 24V step-down circuit 83 shown in FIG. 10 are provided on the stator board 27 in the second embodiment. 12 is a simplified circuit block diagram of the work machine 1 when the 36V step-down circuit 82 and the 24V step-down circuit 83 shown in FIG. 10 are provided on the stator board 27 in the second embodiment. 13 is a circuit diagram showing the current supply circuits to the coils of the relays RY1 to RY5 and the connection relationships by the first conductive pattern 101 to the sixth conductive pattern 106 on the stator board 127 in the third embodiment. 14 is a component layout diagram of the left side of the stator board 127. A component layout diagram of the right surface of the stator board 127, seen from the left through the stator board 27. An explanatory diagram of the wiring pattern of the first layer of the stator board 127. An explanatory diagram of the wiring pattern of the second layer of the stator board 127. An explanatory diagram of the wiring pattern of the third layer of the stator board 127. An explanatory diagram of the wiring pattern of the fourth layer of the stator board 127. A circuit diagram showing a current supply circuit to each coil of relays RY1 to RY5 in embodiment 4. A circuit diagram showing a current supply circuit to each coil of relays RY1 to RY5 in embodiment 5. A circuit diagram of a motor wiring circuit in embodiment 6. (A) is an explanatory diagram of the arrangement of stator coils in embodiment 7.10(B) is an explanatory diagram of the wiring pattern of the stator board 427 in embodiment 7. FIG. 10(A) is a circuit diagram showing the current-carrying circuits to the coils of the relays RY1 to RY5 in embodiment 8, and the connection relationship of the first conductive pattern 201 to the sixth conductive pattern 206 on the stator board 527. FIG. 10(A) is an explanatory diagram of the arrangement of the stator coils in embodiment 8. FIG. 10(B) is an explanatory diagram of the wiring pattern of the stator board 527 in embodiment 8.

[0011] 1 to 17 relate to a work machine 1 according to a first embodiment of the present invention. Figures 1 and 2(A) define the mutually orthogonal front-to-rear, up-down, and left-to-right directions of the work machine 1. The work machine 1 is a bench cutting machine (a bench circular saw).

[0012] The work machine 1 has a base 2, a turntable 3, and a fence 4. The base 2 and the turntable 3 form a base section. The base 2 is placed on a workbench or the like. The turntable 3 is embedded in the center of the base 2 and is rotatable relative to the base 2 by a rotation axis parallel to the vertical direction. The upper surface of the turntable 3 serves as a loading surface (base surface) on which a workpiece such as wood is placed. The upper surfaces of the base 2 and the turntable 3 are substantially flush with each other. The fence 4 is provided on the upper surface of the base 2. Stable cutting operations are possible by abutting the workpiece against the fence 4.

[0013] The work machine 1 has a holder 5. The holder 5 is connected to the rear end of the turntable 3 via a tilting shaft 6 and rises upward from the rear end of the turntable 3. The tilting shaft 6 is a shaft that is substantially parallel to the top surface of the turntable 3 and the side of the cutting blade 20. The axis of the tilting shaft 6 and the top surface of the turntable 3 are at substantially the same position in the up-down direction. The holder 5 can be tilted at a predetermined angle, for example, within a range of 45 degrees, to at least one side of the turntable 3 around the tilting shaft 6. The tilted position of the holder 5 can be fixed or released using a clamp lever (not shown).

[0014] The work machine 1 has a cutting unit 10. The cutting unit 10 is connected to the upper part of the holder 5 via a swing shaft 9 and extends in an upward and forward direction. The swing shaft 9 is a shaft that is approximately parallel to the rotation axis of the cutting blade 20. The cutting unit 10 can swing up and down around the swing shaft 9. A spring (not shown) is provided around the swing shaft 9 to urge the cutting unit 10 upward relative to the holder 5. Figure 1 shows the cutting unit 10 in a state where it is in the upper swing limit position. The cutting unit 10 is connected to the holder 5 via a slide rail (not shown) and can slide in the forward and backward directions relative to the holder 5 with the support of the slide rail.

[0015] The cutting unit 10 has a gear case (saw cover) 11 and a housing 12. The gear case 11 is made of metal such as aluminum. The gear case 11 covers the upper outer periphery of the cutting blade 20. The housing 12 is made of, for example, a resin molded body, and is connected to the gear case 11 and located to the left of the gear case 11. The housing 12 has a handle housing 13 and a motor accommodating portion 17.

[0016] A trigger switch 14 (drive operation unit) that allows the operator to start and stop the motor 30 is provided on the grip portion of the handle housing 13. The rear portion of the motor housing portion 17 is a battery pack attachment portion 16, to which a battery pack 15 can be detachably attached. The work machine 1 operates using power from the battery pack 15. As shown in Figure 2(A), the motor housing portion 17 is formed by combining a motor housing 21 and a cover 22 with screws or the like.

[0017] The motor housing 21 is an undivided cylinder whose central axis is parallel to the left-right direction. A cover 22 covers an opening on the left side of the motor housing 21. The motor housing 21 houses the motor 30 and a stator board 27. An air intake 18 (air window) is provided on the left side of the cover 22 to take in cooling air generated by a fan 50 (described below).

[0018] The cutting unit 10 includes a motor 30. In this example, the motor 30 is a 4-pole, 6-slot brushless motor. The motor 30 includes a motor shaft 31, a rotor core 32, a rotor magnet 33, a stator core 34, a left insulator 35, a right insulator 36, and a stator coil 37 (winding).

[0019] The motor shaft 31 extends perpendicular to the side surface of the cutting blade 20. The left portion of the motor shaft 31 is supported by the left bearing 26. The left bearing 26 is held by the bearing holder 25 of the motor housing 21. The right portion of the motor shaft 31 is supported by the right bearing 51.

[0020] The rotor core 32 has a substantially cylindrical shape and is disposed around the motor shaft 31, rotating integrally with the motor shaft 31. The rotor magnet 33 is inserted and held in the rotor core 32. Four rotor magnets 33 are disposed, for example, at 90-degree intervals around the circumferential direction of the rotor core 32. As shown in FIG. 5 , a sensor magnet 42 is disposed on the left end surface of the rotor core 32. There are four sensor magnets 42, and each is disposed at the same circumferential position as the rotor magnet 33. The magnetic pole faces of the sensor magnet 42 are on the rotor core 32 side and on the opposite side. The magnetic field generated by the sensor magnet 42 is detected by a Hall IC 29, which will be described later. The rotor core 32, rotor magnet 33, and sensor magnet 42 constitute the rotor of the motor 30.

[0021] The stator core 34 is held in the motor housing 21. As shown in FIG. 9 , the stator core 34 has a yoke portion 62 and teeth portions 63. The yoke portion 62 is a tubular portion (cylindrical portion) that coaxially surrounds the rotor core 32. The teeth portions 63 protrude radially inward from the yoke portion 62. Six teeth portions 63 are provided around the stator core 34, for example, at 60-degree intervals. A stator coil 37 is wound around each tooth portion 63. There are two stator coils 37 for each of the U-phase, V-phase, and W-phase. In FIGS. 8A and 8B and 9 , the stator coils 37 are identified as U-phase stator coils U1 and U2, V-phase stator coils V1 and V2, and W-phase stator coils W1 and W2.

[0022] The left insulator 35 is, for example, a resin-molded body, and is provided to the left of the stator core 34 and interposed between the stator coil 37 and the stator core 34. As shown in FIG. 4 , the left insulator 35 serves as a guide for a crossover wire 40 that connects the stator coils 37 of the same phase to the left of the stator core 34 in the circumferential direction of the motor shaft 31. The left insulator 35 holds a connect plate 41, which will be described later. The right insulator 36 is, for example, a resin-molded body, and is provided to the right of the stator core 34 and interposed between the stator coil 37 and the stator core 34. The stator core 34, the left insulator 35, the right insulator 36, the stator coil 37, and the connect plate 41 constitute a stator (stator) of the motor 30.

[0023] The rotation of the motor 30 , i.e., the rotation of the motor shaft 31 , is transmitted forward by the winding transmission mechanism 52 , and is further reduced in speed by the reduction mechanism 53 before being transmitted to the cutting blade 20 .

[0024] The cutting unit 10 has a stator board 27 (sensor board) as a second board. As shown in Fig. 3, the stator board 27 is fixed to the left end of the left insulator 35 by, for example, three screws 38 in an orientation perpendicular to the motor shaft 31. That is, the stator board 27 is disposed at one end of the stator in the axial direction of the motor 30. The stator board 27 has a generally circular disk shape with a smaller diameter than the stator of the motor 30.

[0025] Five relays 28 are provided on the left surface of the stator board 27. In Figures 8A and 8B, the five relays are identified as relays RY1 to RY5. As shown in Figure 5, the relays 28 are configured to be turned on by passing a current through a relay coil 56 wound around an iron core 55, which serves as a magnetic core, causing a movable contact 59 to contact a fixed contact 60. When the current to the relay coil 56 is stopped, the elastic force of the leaf spring 58 causes the movable contact 59 to move away from the fixed contact 60, turning the relays 28 off. Here, the relays 28 are of a through-hole mounting type. That is, the terminals of the relays 28 pass through through holes in the stator board 27 and are electrically connected to the stator board 27 by soldering or the like.

[0026] 5 and 6, a Hall IC 29 serving as a magnetic sensor is provided on the right surface of the stator board 27, i.e., the surface of the stator board 27 opposite the surface on which the relay 28 is mounted. The Hall IC 29 is located inward of the relay 28 in the radial direction of the motor shaft 31. Note that while FIG. 6 shows the left surface of the stator board 27, the Hall IC 29 provided on the right surface of the stator board 27 is indicated by a dashed line. Three Hall ICs 29 are provided at 60-degree intervals around the circumference of the motor shaft 31.

[0027] The stator board 27 and the stator coil 37 are electrically connected by metal connect plates 41 shown in FIGS. 3, 4, and 6. The connect plates 41 are, for example, fuse terminals. The connect plates 41 are held by, for example, integral molding on the left insulator 35. Six connect plates 41 are provided, for example, at 60-degree intervals around the circumferential direction of the motor shaft 31. Note that in FIG. 3, each connect plate 41 is shown in an open state before the stator coil 37 is wound or hooked and clamped. As shown in FIG. 4, a crossover wire 40 connecting the stator coils 37 of the same phase and the end of the stator coil 37 are wound or hooked around each connect plate 41. Each connect plate 41 is electrically connected to the stator board 27 in a closed state as shown in FIG. 4. 6 and 9, the six connect plates 41 are matched to the phases of the corresponding stator coils 37 and are identified as connect plates 41U1, 41U2, 41V1, 41V2, 41W1, and 41W2.

[0028] The cutting unit 10 includes an inverter board 23 (main board) as a first board and a board case 24 that houses and supports it. The board case 24 is located to the left of the bearing holder 25. The inverter board 23 is held within the board case 24 to the left of the bearing holder 25, perpendicular to the motor shaft 31. The inverter board 23 and board case 24 are located to the left of the motor housing 21 and are larger than the left opening of the motor housing 21 when viewed in the axial direction of the motor shaft 31. As shown in FIGS. 2A and 2B, a switching element 49 for energizing the stator coil 37 is provided on the left surface of the inverter board 23. The switching element 49 corresponds to switching elements Q1 to Q6, such as FETs, that constitute the inverter circuit 47 shown in FIG. 7. Note that the switching element 49 is not shown in FIG. 3. The inverter board 23 also includes circuit components, such as a microcontroller, that constitute the calculation unit 80 shown in FIG. 7, but these circuit components are not shown in FIG. 3.

[0029] The inverter board 23 and the stator board 27 are electrically connected by a U-phase power line 43U, a V-phase power line 43V, and a W-phase power line 43W shown in Fig. 6. The U-phase power line 43U extends from the interconnection portion of the switching elements Q1 and Q4 shown in Fig. 7 on the inverter board 23 and is electrically connected to the stator board 27. The V-phase power line 43V extends from the interconnection portion of the switching elements Q2 and Q5 shown in Fig. 7 on the inverter board 23 and is electrically connected to the stator board 27. The W-phase power line 43W extends from the interconnection portion of the switching elements Q3 and Q6 shown in Fig. 7 on the inverter board 23 and is electrically connected to the stator board 27.

[0030] The cutting section 10 includes a fan 50. The fan 50 is a centrifugal fan mounted on the motor shaft 31 to the right of the stator core 34 and rotates integrally with the motor shaft 31. The flow of cooling air generated by the fan 50 is indicated by arrows in FIG. 2A . The cooling air enters the cover 22 through the air intake 18, cools the inverter board 23 and the switching elements 49, then flows around to the right of the inverter board 23 to cool the stator board 27 and the relay 28, and then cools the motor 30 before being drawn into the fan 50. In other words, the relay 28 is located downstream of the cooling air relative to the switching elements 49. The gap between the inner edge of the through-hole 44 in the center of the stator board 27 and the outer circumferential surface of the motor shaft 31 (see FIG. 2B ), and the gap between the notch 39 at the left end of the left insulator 35 and the stator board 27 (see FIG. 3 ) form air paths through which the cooling air flows toward the motor 30 after cooling the stator board 27 and the relay 28. The cooling air drawn into the fan 50 flows in a centrifugal direction, is guided by the inner wall of the housing 12, flows to the right, and is exhausted to the outside of the housing 12 through an exhaust port (not shown).

[0031] FIG. 7 is a circuit block diagram of the work machine 1. FIGS. 8A and 8B show a specific configuration of the motor connection circuit 46 shown in FIG. 7 . The motor connection circuit 46 includes U-phase stator coils U1 and U2, V-phase stator coils V1 and V2, W-phase stator coils W1 and W2, and relays RY1 to RY5. Relays RY1 to RY5 are connection switching units that switch the connections of the U-phase stator coils U1 and U2, V-phase stator coils V1 and V2, and W-phase stator coils W1 and W2 (hereinafter referred to as "stator coil connections") between a delta connection and a star connection (Y connection), and are examples of second switch units. The nominal heat resistance temperatures of relays RY1 to RY5 (hereinafter referred to as "relay heat resistance temperatures") are higher than the nominal heat resistance temperatures of switching elements Q1 to Q6 of the inverter circuit 47 (hereinafter referred to as "FET heat resistance temperatures").

[0032] When the stator coils are connected in a delta connection as the first connection, relays RY1 to RY3 are on (conducting state), and relays RY4 and RY5 are off (disconnecting state). When the stator coils are connected in a star connection as the second connection, relays RY1 to RY3 are off (disconnecting state), and relays RY4 and RY5 are on (conducting state). Relays RY1 to RY3 are relays for a delta connection and are examples of the first connection part. Relays RY4 and RY5 are relays for a star connection and are examples of the second connection part.

[0033] The inverter circuit 47 is a drive unit that converts the direct current output from the battery pack 15 into alternating current and supplies it to the motor connection circuit 46 to drive the motor 30. The inverter circuit 47 includes switching elements Q1 to Q6, such as FETs and IGBTs, connected in a three-phase bridge. The switching elements Q1 to Q6 are examples of a first switch unit. A resistor 48 is provided in the path of the current (hereinafter referred to as "motor current") flowing through the motor connection circuit 46. A current detection circuit 71 detects the motor current by the voltage drop across the resistor 48 and transmits it to the calculation unit 80. A voltage detection circuit 72 detects the output voltage of the battery pack 15 (hereinafter referred to as "battery voltage") and transmits it to the calculation unit 80. A manipulation amount detection circuit 73 detects the on / off status and manipulation amount of the trigger switch 14 and transmits it to the calculation unit 80.

[0034] Thermistor 75, which serves as a temperature detection element, is provided on inverter board 23 and positioned near one of switching elements Q1 to Q6, and outputs a signal corresponding to the temperature of that switching element (hereinafter referred to as "FET temperature"). Temperature detection circuit 74 detects the temperature of that switching element from the signal from thermistor 75 and sends the detected temperature to calculation unit 80. Note that switching elements Q1 to Q6 are identical elements, have common on-resistances, heat resistance temperatures, etc., and exhibit substantially the same temperature changes. For this reason, it is sufficient to monitor the temperature change of one of switching elements Q1 to Q6.

[0035] The rotor position detection circuit 76 detects the rotor rotation position of the motor 30 based on the output signal of the Hall IC 29 and transmits the detected signal to the calculation unit 80. The rotation speed detection circuit 77 detects the rotation speed of the motor 30 (hereinafter referred to as "motor rotation speed") based on the output signal of the rotor position detection circuit 76 and transmits the detected signal to the calculation unit 80. The relay drive circuit 78 controls the on / off of the relays 28 (relays RY1 to RY5) under the control of the calculation unit 80. The control signal output circuit 79 controls the on / off of the switching elements Q1 to Q6 of the inverter circuit 47 under the control of the calculation unit 80.

[0036] The calculation unit 80 is a control unit that controls the overall operation of the work machine 1. The calculation unit 80 monitors the motor current, battery voltage, the on / off and operation amount of the trigger switch 14, the FET temperature, the rotor rotation position, and the motor rotation speed, and controls the drive of the inverter circuit 47 (PWM control) via the control signal output circuit 79 in accordance with the operation of the trigger switch 14, thereby controlling the drive of the motor 30.

[0037] The calculation unit 80 has an overload protection function (overcurrent protection function) that turns off all of the switching elements Q1 to Q6 and stops the supply of power to the motor 30 when the motor current satisfies an overload protection activation condition (overcurrent protection activation condition), even if the trigger switch 14 is on. The overload protection activation condition is, for example, when the motor current exceeds an overload protection threshold (overcurrent protection threshold).

[0038] The calculation unit 80 has a high temperature protection activation function that, when the FET temperature satisfies a high temperature protection activation condition, turns off all of the switching elements Q1 to Q6 even if the trigger switch 14 is on, and stops the supply of power to the motor 30. The high temperature protection activation condition is, for example, when the FET temperature reaches or exceeds a predetermined temperature (high temperature protection threshold).

[0039] In the overload protection function and the high temperature protection activation function, turning off all of the switching elements Q1 to Q6 to stop the supply of power to the motor 30 is an example of control so that no current flows through the relays RY1 to RY5 (power supply to the relays RY1 to RY5 is cut off). Instead of or in addition to turning off all of the switching elements Q1 to Q6, the calculation unit 80 may turn off all of the relays RY1 to RY5.

[0040] When the motor 30 is driven, the FET temperature and the temperatures of the relays RY1 to RY5 (hereinafter referred to as "relay temperature") rise. For this reason, it is conceivable to perform both control by monitoring the FET temperature to prevent the FET temperature from exceeding the FET heat resistance temperature, and control by monitoring the relay temperature to prevent the relay temperature from exceeding the relay heat resistance temperature. However, providing a thermistor 75 for monitoring the FET temperature and a thermistor for monitoring the relay temperature separately could increase costs, increase the size of the stator board 27 for mounting the thermistors, and ultimately increase the size of the work machine 1.

[0041] Therefore, the work machine 1 is configured so that the FET temperature satisfies the high-temperature protection activation condition before the relay temperature reaches the relay heat-resistant temperature. That is, when the FET temperature exceeds a predetermined temperature (high-temperature protection threshold), the relay temperature becomes lower than the relay heat-resistant temperature. With this configuration, the work machine 1 does not have a dedicated thermistor for monitoring the relay temperature, and the calculation unit 80 indirectly controls the relay temperature to prevent it from exceeding the relay heat-resistant temperature by controlling the FET temperature to prevent it from exceeding the FET heat-resistant temperature.

[0042] As shown in Figures 8A and 8B, the U-phase stator coils U1 and U2 are connected in parallel, the V-phase stator coils V1 and V2 are connected in parallel, and the W-phase stator coils W1 and W2 are connected in parallel. Figure 8B shows that the parallel connection (parallel wiring) of the stator coils of each phase is completed on the stator 45 side, that is, is established without relying on the conductive pattern (wiring pattern) of the stator board 27. This allows for only six connect plates 41 and prevents the conductive pattern of the stator board 27 from becoming too complicated.

[0043] 9 is an explanatory diagram of the winding process of the stator 45. In the example shown in this figure, the beginning of the winding of the wire that will become the stator coil is wound around the connect plate 41U2, the stator coil U2 is wound, and the wire is routed 180 degrees clockwise in FIG. 9 and hooked onto the connect plate 41U1, the stator coil U1 is wound, and the wire is routed 180 degrees clockwise in FIG. 9 and hooked onto the connect plate 41U2. As a result, the U-phase stator coils U1 and U2 are connected in parallel with each other.

[0044] Next, the wire hooked onto connect plate 41U2 is routed 60 degrees clockwise in Fig. 9, hooked onto connect plate 41W1, wound with stator coil W1, routed 180 degrees clockwise in Fig. 9, hooked onto connect plate 41W2, wound with stator coil W2, routed 180 degrees clockwise in Fig. 9, and hooked onto connect plate 41W1. As a result, the W-phase stator coils W1 and W2 are connected in parallel to each other.

[0045] Next, the wire hooked onto connect plate 41W1 is routed 60 degrees clockwise in Fig. 9, hooked onto connect plate 41V2, wound with stator coil V2, routed 180 degrees clockwise in Fig. 9, hooked onto connect plate 41V1, wound with stator coil V1, routed 180 degrees counterclockwise in Fig. 9, and the end of the winding is entangled with connect plate 41V2. As a result, the V-phase stator coils V1 and V2 are connected in parallel.

[0046] The above winding process can be performed using an automatic winding machine (not shown). Next, unnecessary portions of the wire (portions indicated by two-dot chain lines in FIG. 9), i.e., the portion spanning between connect plates 41U2 and 41W1 and the portion spanning between connect plates 41W1 and 41V2, are cut and removed. This completes the connection shown within the dashed lines in stator 45 in FIG. 8(B). The crossover wires 40 and each connect plate 41 connecting stator coils of the same phase are examples of common connections. In the above winding process, there is no particular restriction on which stator coil to start winding.

[0047] FIG. 10 is a circuit diagram showing the current supply circuits to the coils of the relays RY1 to RY5 shown in FIG. 8 and the connection relationships between the first conductive pattern 91 to the sixth conductive pattern 96 on the stator substrate 27.

[0048] The inverter board 23 is provided with a control circuit power supply 81, a 36V step-down circuit 82 as a first step-down circuit, and a 24V step-down circuit 83 as a second step-down circuit. The control circuit power supply 81 generates 5V DC from the battery voltage and supplies it as a power supply voltage to the calculation unit 80 shown in FIG. 7 and the like, as well as to the stator board 27. The battery voltage is set to 40V as an example here. The battery voltage is an example of a power supply voltage supplied from an external source.

[0049] The 36V step-down circuit 82 steps down the battery voltage to 36V DC and supplies it to each coil of relays RY1 to RY3. The coils of relays RY1 to RY3 and a delta-side relay switching circuit 85 are connected in series between the output terminal of the 36V step-down circuit 82 and ground. The on / off of the delta-side relay switching circuit 85 is controlled by a relay operation signal from the calculation unit 80 shown in FIG. 7. When the delta-side relay switching circuit 85 is on (conductive), a voltage of 12V is applied to the coils of relays RY1 to RY3, and relays RY1 to RY3 are each on (conductive). In this example, the rated coil voltage of relays RY1 to RY3 (the optimal value of the voltage applied to the coil to turn on the relay) is assumed to be 12V. The delta-side relay switching circuit 85 is provided on the stator board 27 and constitutes part of the relay drive circuit 78 shown in FIG. 7.

[0050] The 24V step-down circuit 83 steps down the battery voltage to 24V DC and supplies it to each coil of relays RY4 to RY5. The step-down rate of the 24V step-down circuit 83 (40V → 24V) is higher than the step-down rate of the 36V step-down circuit 82 (40V → 36V). The coils of relays RY4 to RY5 and a star-side relay switching circuit 86 (Y-side relay switching circuit) are connected in series between the output terminal of the 24V step-down circuit 83 and ground. The on / off of the star-side relay switching circuit 86 is controlled by a relay operation signal from the calculation unit 80 shown in FIG. 7. When the star-side relay switching circuit 86 is on (conductive state), a voltage of 12V is applied to the coils of relays RY4 to RY5, and relays RY4 to RY5 are each on (conductive state). In this example, the rated coil voltage of relays RY4 to RY5 is 12V. The star-side relay switching circuit 86 is provided on the stator board 27 and constitutes a part of the relay drive circuit 78 shown in FIG.

[0051] The Hall IC signal detection circuit 84 is a circuit that outputs signals from the three Hall ICs 29 shown in FIG.

[0052] 10 and 13 to 16, a ground pattern 87 and first to sixth conductive patterns 91 to 96, which are patterns through which a large current flows, are provided on the stator substrate 27. In FIGS. 13 to 16, the ground pattern 87 and the first to sixth conductive patterns 91 to 96 are indicated by hatching. The ground pattern 87 and the first to sixth conductive patterns 91 to 96 are conductive patterns for large current.

[0053] The first conductive pattern 91 electrically connects the U-phase power supply line connection portion 67U to which the U-phase power supply line 43U is connected, one end of the relay RY1, and the connect plate 41U1 to one another.

[0054] The second conductive pattern 92 electrically connects a V-phase power supply line connection portion 67V to which the V-phase power supply line 43V is connected, one end of the relay RY2, and the connect plate 41V1 ​​to one another.

[0055] The third conductive pattern 93 electrically connects the W-phase power supply line connection portion 67W to which the W-phase power supply line 43W is connected, one end of the relay RY3, and the connect plate 41W1 to one another.

[0056] The fourth conductive pattern 94 electrically connects the other end of the relay RY1, the connect plate 41W2, and one end of the relay RY5 to one another.

[0057] The fifth conductive pattern 95 electrically connects the other end of the relay RY2, the connect plate 41U2, and one end of the relay RY4 to one another.

[0058] The sixth conductive pattern 96 electrically connects the other end of each of the relays RY3 to RY5 to the connect plate 41V2.

[0059] 13 to 16, the ground pattern 87 and the first conductive pattern 91 to the sixth conductive pattern 96 are provided across the first layer (left surface), second layer, third layer, and fourth layer (right surface), which are conductive layers of the stator substrate 27, overlapping each other with insulating layers interposed therebetween and electrically connected to each other via through holes. The pattern shapes (shapes viewed from a direction perpendicular to the stator substrate 27) of the ground pattern 87 and the first conductive pattern 91 to the sixth conductive pattern 96 are identical on the first to third layers and overlap each other. Due to the provision of conductive patterns for signals on the fourth layer, some of the conductive patterns are reduced compared to the first to third layers.

[0060] FIG. 11 is a diagram showing the arrangement of components on the left surface of the stator board 27.

[0061] The U-phase power supply line connection portion 67U, the V-phase power supply line connection portion 67V, and the W-phase power supply line connection portion 67W are arranged spaced apart from one another in the circumferential direction of the motor 30.

[0062] In the circumferential direction of motor 30, relay RY1 is located between U-phase power line connection portion 67U and V-phase power line connection portion 67V, relays RY2 and RY4 are located between V-phase power line connection portion 67V and W-phase power line connection portion 67W, and relays RY3 and RY5 are located between W-phase power line connection portion 67W and U-phase power line connection portion 67U. In other words, in the circumferential direction of motor 30, at least one of relays RY1 to RY5 is located between U-phase power line connection portion 67U, V-phase power line connection portion 67V, and W-phase power line connection portion 67W, respectively.

[0063] Relay RY2, relay RY4, relay RY3, relay RY5, and relay RY1 are arranged in this order in the circumferential direction of the motor 30. In other words, relays RY1 to RY3, which are delta-connection relays, and relays RY4 to RY5, which are star-connection relays, are arranged alternately in the circumferential direction of the motor 30.

[0064] The longitudinal direction of relays RY1 and RY3 is approximately parallel to the radial direction of the motor 30. The longitudinal direction of relays RY2, RY4 to RY5 is approximately parallel to the circumferential direction of the motor 30. In the circumferential direction of the motor 30, relay RY1 and relay RY5 are adjacent to each other, relays RY3 and RY4 are adjacent to each other, and relays RY3 and RY5 are adjacent to each other. In other words, a relay whose longitudinal direction is approximately parallel to the radial direction of the motor 30 and a relay whose longitudinal direction is approximately parallel to the circumferential direction of the motor 30 are adjacent to each other in the circumferential direction of the motor 30.

[0065] 12 is a component layout diagram of the right surface of the stator board 27, seen from the left through the stator board 27. Three Hall ICs 29 are lined up in the circumferential direction of the motor 30. Two Hall ICs 29 are located within the ranges of relays RY2 and RY4 in the circumferential direction of the motor 30, and are located inside relays RY2 and RY4 in the radial direction of the motor 30.

[0066] 10 is provided on the inverter board 23. When the 36V step-down circuit 82 and the 24V step-down circuit 83 are provided on the inverter board 23, no space is required on the stator board 27 for providing the 36V step-down circuit 82 and the 24V step-down circuit 83, so the areas of the ground pattern 87 and the first to sixth conductive patterns 91 to 96 can be increased (pattern widths can be increased), and the allowable current value can be increased.

[0067] This embodiment has the following advantages.

[0068] (1) Relays RY1 to RY5 that switch the stator coil connection between a delta connection as a first connection and a star connection are provided on the stator board 27, and the stator board 27 is disposed at one end of the stator in the axial direction of the motor 30. Therefore, it is possible to provide a work machine 1 in which the stator board 27, on which the relays RY1 to RY5 that switch between the delta connection and the star connection are provided, is disposed in an appropriate location.

[0069] (2) The U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W are spaced apart from one another in the circumferential direction of the motor 30, with relay RY1 located between the U-phase power line connection portion 67U and the V-phase power line connection portion 67V, relays RY2 and RY4 located between the V-phase power line connection portion 67V and the W-phase power line connection portion 67W, and relays RY3 and RY5 located between the W-phase power line connection portion 67W and the U-phase power line connection portion 67U. This positions each of the U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W close to the relay to which it is connected, among relays RY1 to RY5. Therefore, the ground pattern 87 and the first to sixth conductive patterns 91 to 96 can be stacked and electrically connected to one another with the same shape across the first to third layers of the stator board 27. Therefore, even though the outer diameter of the stator board 27 is limited by the inner diameter of the motor housing 21, it is possible to increase the effective pattern width (the product of the pattern width of each layer and the number of layers) of the ground pattern 87 and the first conductive pattern 91 to the sixth conductive pattern 96, through which a large current flows, while mounting the relays RY1 to RY5. This makes it possible to reduce power loss in the stator board 27 and increase the allowable current value of the stator board 27. It is also easy to ensure the inter-pattern distance (distance between different potentials) between the ground pattern 87 and the first conductive pattern 91 to the sixth conductive pattern 96, through which a large current flows.

[0070] (3) The coils of relays RY1 to RY3 are connected in series to each other and receive power from a 36V step-down circuit 82. The coils of relays RY4 to RY5 are connected in series to each other and receive power from a 24V step-down circuit 83. Therefore, the step-down range of the 36V step-down circuit 82 and the 24V step-down circuit 83 is smaller than that of a step-down circuit that steps down the battery voltage to 12V, which is the rated coil voltage of one relay. This reduces power consumption and heat generation due to the step-down, and allows the 36V step-down circuit 82 and the 24V step-down circuit 83 to be made smaller in size.

[0071] (4) Relays RY1 to RY5 are arranged such that relays whose longitudinal direction is approximately parallel to the radial direction of motor 30 and relays whose longitudinal direction is approximately parallel to the circumferential direction of motor 30 are adjacent to each other in the circumferential direction of motor 30. This simplifies the layout of the conductive patterns, through holes for screw fastening, and the like on stator board 27 compared to when the longitudinal directions of all relays are parallel to the circumferential direction of motor 30, parallel to the radial direction of motor 30, or parallel to each other.

[0072] (5) The 36V step-down circuit 82 and the 24V step-down circuit 83 are provided on the inverter board 23. Therefore, no space is required on the stator board 27 for providing the 36V step-down circuit 82 and the 24V step-down circuit 83. This allows the areas of the ground pattern 87 and the first to sixth conductive patterns 91 to 96 provided on the stator board 27 to be increased (the pattern widths can be increased), making it possible to reduce power loss and increase the allowable current value.

[0073] (6) As shown in Figures 8(B) and 9, the parallel connection of U-phase stator coils U1 and U2 (hereinafter referred to as the "U-phase parallel connection"), the parallel connection of V-phase stator coils V1 and V2 (hereinafter referred to as the "V-phase parallel connection"), and the parallel connection of W-phase stator coils W1 and W2 (hereinafter referred to as the "W-phase parallel connection") are each completed on the stator 45 side without relying on the conductive patterns of the stator board 27. Therefore, compared to when the connections between the stator coils in each parallel connection are configured using the conductive patterns of the stator board 27, the number of connect plates 41 can be reduced, the conductive patterns of the stator board 27 can be made less complex, and the conductive patterns through which large currents flow can be reduced. This reduces the size of the stator board 27, thereby preventing increases in cost and size of the product. On the other hand, the interconnection configuration between the U-phase parallel connection, the V-phase parallel connection, and the W-phase parallel connection, i.e., the stator coil wiring, is not fixed on the stator 45 side, so the stator coil wiring can be dynamically switched by the relays RY1 to RY5 provided on the stator board 27.

[0074] (7) As shown in Figure 9, the stator winding process is efficient, as it involves winding all slots at once and then cutting off the unnecessary parts. In addition, the connect plate 41 allows for electrical connection to the stator board 27 while connecting stator coils of the same phase, which helps prevent an increase in the number of parts and simplifies the structure.

[0075] (8) As shown in Figure 2A, the switching element 49 is positioned upstream of the cooling air from the relay 28. Therefore, the cooling air that cools the relay 28 can cool the switching element 49, which generates a large amount of heat, before its temperature rises, and the rise in the FET temperature can be effectively suppressed.

[0076] (9) The motor housing 21 that holds the stator core 34 is a single (undivided) member. Therefore, compared to a case where the motor housing 21 has a two-piece structure, the coaxial accuracy of the bearing holder 25 of the motor housing 21 and the stator core 34 is improved, and the coaxial accuracy of the motor shaft 31 and the stator core 34 is also improved.

[0077] (Embodiment 2) Fig. 18 is a simplified circuit block diagram of embodiment 2 in which the 36V step-down circuit 82 and the 24V step-down circuit 83 shown in Fig. 10 are provided on the stator board 27. When the 36V step-down circuit 82 and the 24V step-down circuit 83 are provided on the stator board 27, the circuits constituting the winding switching function are integrated on the stator board 27, making it easier to deploy the stator board 27 as a board that integrates the winding switching function for multiple models (enhancing the versatility of the stator board 27). In addition, the amount of wiring between the stator board 27 and the inverter board 23 can be reduced. Other aspects of this embodiment are the same as those of embodiment 1, and the same effects as those of embodiment 1 are achieved.

[0078] 19 to 25 relate to a third embodiment of the present invention. The following description will focus on the differences from the first embodiment.

[0079] FIG. 19 is a circuit diagram showing the current-carrying circuits to the coils of the relays RY1 to RY5 and the connection relationships of the first conductive pattern 101 to the sixth conductive pattern 106 on the stator substrate 127 in the third embodiment.

[0080] 19 and 22 to 25, the stator substrate 127 is provided with the first to sixth conductive patterns 101 to 106, which are patterns through which a large current flows, and the ground pattern 107. In FIGS. 22 to 25, the first to sixth conductive patterns 101 to 106 and the ground pattern 107 are indicated by hatching.

[0081] The first conductive pattern 101 electrically connects the U-phase power supply line connection portion 67U to which the U-phase power supply line 43U is connected, one end of the relay RY1, and the connect plate 41U1 to one another.

[0082] The second conductive pattern 102 electrically connects a V-phase power supply line connection portion 67V to which the V-phase power supply line 43V is connected, one end of the relay RY2, and the connect plate 41V1 ​​to one another.

[0083] The third conductive pattern 103 electrically connects the W-phase power supply line connection portion 67W to which the W-phase power supply line 43W is connected, one end of the relay RY3, and the connect plate 41W1 to one another.

[0084] The fourth conductive pattern 104 electrically connects the other ends of the relays RY1, RY4, and RY5 to the connect plate 41W2.

[0085] The fifth conductive pattern 105 electrically connects the other end of the relay RY2, the connect plate 41U2, and one end of the relay RY4 to one another.

[0086] The sixth conductive pattern 106 electrically connects the other end of the relay RY3, the connect plate 41V2, and one end of the relay RY5 to one another.

[0087] 22 , the first conductive pattern 101 and the third conductive pattern 103 are provided on the first layer (left surface) of the stator substrate 127. As shown in FIG. 23 , the second conductive pattern 102, the fourth conductive pattern 104, the fifth conductive pattern 105, and the sixth conductive pattern 106 are provided on the second layer of the stator substrate 127.

[0088] 22 and 23 , the first conductive pattern 101 of the first layer and the fourth conductive pattern 104 of the second layer partially overlap with each other with an insulating layer sandwiched therebetween, and the third conductive pattern 103 of the first layer and the second conductive pattern 102, the fourth conductive pattern 104, and the sixth conductive pattern 106 of the second layer partially overlap with each other with an insulating layer sandwiched therebetween.

[0089] As shown in Figures 22 to 25, ground patterns 107 are provided across the first to fourth layers of stator substrate 127, and are electrically connected to each other by through holes where they overlap with an insulating layer sandwiched between them. As shown in Figure 24, the third layer is entirely made up of ground pattern 107, except for areas that require insulation from ground pattern 107. As shown in Figure 25, in addition to ground pattern 107, a conductive pattern for signals is provided on the fourth layer.

[0090] FIG. 20 is a component layout diagram on the left side of the stator board 127.

[0091] The U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W are arranged close to one another in the circumferential direction of the motor 30. Relay RY2, relay RY4, relay RY5, relay RY3, and relay RY1 are arranged in this order in the circumferential direction of the motor 30, and the U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W are located between relays RY1 and RY2. Relays RY1 to RY3 are arranged in positions close to the U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W in the circumferential direction of the motor 30, and relays RY4 and RY5 are arranged in positions away from the U-phase power line connection portion 67U, the V-phase power line connection portion 67V, and the W-phase power line connection portion 67W. The relative positions of relays RY1 to RY3 and relays RY4 and RY5 with respect to U-phase power line connection portion 67U, V-phase power line connection portion 67V, and W-phase power line connection portion 67W may be reversed.

[0092] The longitudinal direction of relays RY1 to RY3, and RY5 is approximately parallel to the circumferential direction of the motor 30. The longitudinal direction of relay RY4 is approximately parallel to the radial direction of the motor 30. Relays RY2 and RY4 are adjacent to each other, and relays RY4 and RY5 are adjacent to each other in the circumferential direction of the motor 30. In other words, a relay whose longitudinal direction is approximately parallel to the radial direction of the motor 30 and a relay whose longitudinal direction is approximately parallel to the circumferential direction of the motor 30 are adjacent to each other in the circumferential direction of the motor 30.

[0093] 21 is a component layout diagram of the right surface of the stator board 127, seen from the left through the stator board 127. Three Hall ICs 29 are lined up in the circumferential direction of the motor 30. Two Hall ICs 29 are located within the ranges of relays RY1 and RY2 in the circumferential direction of the motor 30, and are located inside relays RY1 and RY2 in the radial direction of the motor 30.

[0094] In this embodiment, the effective pattern widths of the first conductive pattern 101 to the sixth conductive pattern 106 are smaller than the effective pattern widths of the first conductive pattern 91 to the sixth conductive pattern 96 in the first embodiment. Meanwhile, the U-phase power supply line connection portion 67U, the V-phase power supply line connection portion 67V, and the W-phase power supply line connection portion 67W are disposed close to one another in the circumferential direction of the motor 30, resulting in a layout in which the U-phase power supply line 43U, the V-phase power supply line 43V, and the W-phase power supply line 43W are consolidated. Therefore, even when the relays RY1 to RY5 are mounted on the stator board 127, it is possible to prevent difficulties in connecting the U-phase power supply line 43U, the V-phase power supply line 43V, and the W-phase power supply line 43W to the inverter board 23, thereby preventing deterioration in assembly. Other aspects of this embodiment are similar to those of the first embodiment, and similar effects are achieved.

[0095] 26 is a circuit diagram showing a current supply circuit to each coil of relays RY1 to RY5 in embodiment 4. The following description will focus on the differences from embodiment 1.

[0096] The inverter board 123 is configured such that the 36V step-down circuit 82 in the inverter board 23 of Fig. 10 is replaced with a 12V step-down circuit 90. The 12V step-down circuit 90 steps down the battery voltage to 12V DC and supplies it to the coil of the relay RY1. In this embodiment, the 24V step-down circuit 83 corresponds to the first step-down circuit, and the 12V step-down circuit 90 corresponds to the second step-down circuit.

[0097] The stator board 227 has a different connection relationship for the coils of relays RY1 to RY5 than the stator board 27 of Fig. 10. The coil of relay RY1 and the delta-side relay switching circuit 85 are connected in series between the output terminal of the 12V step-down circuit 90 and ground. The coils of relays RY2 to RY3 and the delta-side relay switching circuit 85 are connected in series between the output terminal of the 24V step-down circuit 83 and ground, and the coils of relays RY4 to RY5 and the star-side relay switching circuit 86 (Y-side relay switching circuit) are connected in series in parallel with relays RY2, etc. Because relays RY2 to RY3 and relays RY4 to RY5 are not turned on at the same time, relays RY2 to RY3 and relays RY4 to RY5 share the 24V step-down circuit 83 as the power source for the coils.

[0098] According to this embodiment, the 36V step-down circuit 82 of embodiment 1 has been replaced with a 12V step-down circuit 90, which allows for a larger step-down range, but also allows for a suitable response to a drop in battery voltage. That is, although the battery voltage fluctuates between 30 and 40V depending on the remaining charge of the battery pack 15, the 12V step-down circuit 90 can output 12V even when the battery voltage drops below 36V, allowing for a suitable response to a drop in battery voltage. Furthermore, because the coils of relays RY2 and RY3 and the coils of relays RY4 and RY5 receive power from the common 24V step-down circuit 83, an increase in the number of step-down circuits can be suppressed. Other aspects of this embodiment are similar to those of embodiment 1, and similar effects are achieved.

[0099] 27 is a circuit diagram showing a current supply circuit to each coil of relays RY1 to RY5 in embodiment 5. The following description will focus on the differences from embodiment 4.

[0100] 26 , the 24V step-down circuit 83 is replaced with 12V step-down circuits 98, 99. The 12V step-down circuits 98, 99 step down the battery voltage to 12V DC and supply it to the coils of relays RY2 to RY5. In this embodiment, the 12V step-down circuits 98, 99 correspond to the first and second step-down circuits, and the 12V step-down circuit 90 corresponds to the third step-down circuit.

[0101] The stator board 327 is different from the stator board 227 of FIG. 26 in that the connection relationship of the coils of the relays RY1 to RY5 is changed.

[0102] Between the output terminal of the 12V step-down circuit 98 and the ground, the coil of relay RY2 and the delta side relay switching circuit 85 are connected in series, and the coil of relay RY4 and the star side relay switching circuit 86 (Y side relay switching circuit) are connected in series in parallel with relays RY2, etc. Since relays RY2 and RY4 are not turned on at the same time, relays RY2 and RY4 share the 12V step-down circuit 98 as the power supply source for their coils.

[0103] Between the output terminal of the 12V step-down circuit 99 and the ground, the coil of relay RY3 and the delta side relay switching circuit 85 are connected in series, and the coil of relay RY5 and the star side relay switching circuit 86 (Y side relay switching circuit) are connected in series in parallel with relays RY3, etc. Since relays RY3 and RY5 are not turned on at the same time, relays RY3 and RY5 share the 12V step-down circuit 99 as the power supply source for their coils.

[0104] According to this embodiment, the 24V step-down circuit 83 of the fourth embodiment is replaced with 12V step-down circuits 98, 99, so that the step-down range is increased and the number of step-down circuits is also increased, but this embodiment can be suitably adapted to cases where a battery pack with a low rated voltage as a power source, for example, a battery pack with a rated voltage of 18 V, is desired to be used. In other respects, this embodiment is similar to the fourth embodiment, and provides similar functions and effects.

[0105] (Embodiment 6) Figures 28(A) and (B) are circuit diagrams of a motor connection circuit in embodiment 6. Figure 28(A) shows the delta connection state, and Figure 28(B) shows the star connection state (Y connection). The following describes differences from embodiment 1, focusing on the differences. Relay RY6 is a C-contact relay and also functions as relays RY2 and RY4 in Figure 8(A), which are A-contact relays. Relay RY7 is a C-contact relay and also functions as relays RY1 and RY5 in Figure 8(A), which are A-contact relays. According to this embodiment, the total number of relays can be reduced by using C-contact relays. Furthermore, because only three relays are required, only one 36V step-down circuit is required to supply power to the relay coil, thereby reducing the number of step-down circuits. Other aspects of this embodiment are similar to those of embodiment 1, and similar effects are achieved.

[0106] (Embodiment 7) Figure 29(A) is an explanatory diagram of the arrangement of U-phase stator coils U1 and U2, V-phase stator coils V1 and V2, and W-phase stator coils W1 and W2 in embodiment 7. Figure 29(B) is an explanatory diagram of the wiring pattern of a stator board 427 in embodiment 7. The following description will focus on differences from embodiment 1.

[0107] The arrangement shown in Figure 29(A) is obtained by interchanging the positions of the V-phase stator coils V1 and V2 in the arrangement of embodiment 1 shown in Figure 9. In the arrangement of the stator coils shown in Figure 29(A), even if the U-phase power supply line connection portion 67U, the V-phase power supply line connection portion 67V, and the W-phase power supply line connection portion 67W are arranged close to each other in the circumferential direction of the motor 30 as shown in Figure 29(B), the first conductive pattern 91 to the sixth conductive pattern 96 can be arranged together on one layer as in embodiment 1. Therefore, as in embodiment 1, the first conductive pattern 91 to the sixth conductive pattern 96 can be stacked and electrically connected to each other with the same shape across the first to third layers of the stator substrate 427, thereby reducing power loss in the stator substrate 427 and increasing the allowable current value of the stator substrate 427. 29(B), the position of the connect plate 41W1 is separated from the end of the stator substrate 427, thereby passing the second conductive pattern 92 between the connect plate 41W1 and the end of the stator substrate 427 and ensuring an area for the second conductive pattern 92. Other points of this embodiment are the same as those of embodiment 1, and similar effects are achieved.

[0108] (Embodiment 8) Figure 30 is a circuit diagram showing the current-carrying circuits to the coils of relays RY1 to RY5 in embodiment 8, and the connection relationships of the first to sixth conductive patterns 201 to 206 on a stator board 527. Figure 31(A) is an explanatory diagram of the arrangement of U-phase stator coils U1 to U3, V-phase stator coils V1 to V3, and W-phase stator coils W1 to W3 in embodiment 8. Figure 31(B) is an explanatory diagram of the wiring pattern of the stator board 527 in embodiment 8. The following will mainly explain the differences from embodiment 1. Embodiment 8 corresponds to a motor 30 of embodiment 1 with nine slots.

[0109] The first conductive pattern 201 electrically connects the U-phase power supply line connection portion 67U to which the U-phase power supply line 43U is connected, one end of the relay RY1, and the connect plate 41U1 to one another.

[0110] The second conductive pattern 202 electrically connects a V-phase power supply line connection portion 67V to which the V-phase power supply line 43V is connected, one end of the relay RY2, and the connect plate 41V1 ​​to one another.

[0111] The third conductive pattern 203 electrically connects the W-phase power supply line connection portion 67W to which the W-phase power supply line 43W is connected, one end of the relay RY3, and the connect plate 41W1 to one another.

[0112] The fourth conductive pattern 204 electrically connects the other end of the relay RY1, one end of the relay RY5, and the connect plate 41W3 to one another.

[0113] The fifth conductive pattern 205 electrically connects the other ends of the relays RY2, RY4, and RY5 to the connect plate 41U3.

[0114] The sixth conductive pattern 206 electrically connects the other end of the relay RY3, the connect plate 41V3, and one end of the relay RY4 to one another.

[0115] 31(B), the first conductive pattern 201 to the sixth conductive pattern 206 can be arranged together on one layer, as in embodiment 1. Therefore, as in embodiment 1, the first conductive pattern 201 to the sixth conductive pattern 206 can be stacked in the same shape across the first to third layers of the stator substrate 527 and electrically connected to each other, which makes it possible to reduce power loss in the stator substrate 527 and increase the allowable current value of the stator substrate 527. Other aspects of this embodiment are the same as those of embodiment 1, and similar effects are achieved.

[0116] Although the present invention has been described above using the embodiments as examples, the present invention is not limited to the embodiments. Various modifications can be made to the details specifically described in the embodiments within the scope of the claims.

[0117] The number of rotor poles, the number of stator slots, the battery voltage, the output voltage of the step-down circuit, and other specific values ​​exemplified in the embodiments do not limit the scope of the invention and can be changed as desired to meet required specifications. The motor 30 may be sensorless driven. That is, the Hall IC 29 may be omitted. The relays RY1 to RY5, which are A-contact relays, may be B-contact relays. The work machine of the present invention is not limited to a bench cutter, and may be another type of cutter, such as a portable circular saw, or another type of work machine, such as a grinder.

[0118] DESCRIPTION OF SYMBOLS 1...Working machine, 2...Base, 3...Turntable, 4...Fence, 5...Holder, 6...Tilt axis, 9...Oscillating axis (shaft), 10...Cutting section (head section), 11...Gear case (saw cover), 12...Housing, 13...Handle housing, 14...Trigger switch (drive operation section), 15...Battery pack, 16...Battery pack mounting section, 17...Motor accommodating section, 18...Air intake, 20...Cutting blade (saw blade), 21...Motor housing, 22...Cover, 23...Inverter base Plate (first board), 24... board case, 25... bearing holder, 26... left bearing, 27... stator board (second board), 28... relay, 29... Hall IC (magnetic sensor), 30... motor, 31... motor shaft, 32... rotor core, 33... rotor magnet, 34... stator core, 35... left insulator, 36... right insulator, 37... stator coil, 38... screw, 39... notch, 40... jumper wire, 41, 41U1, 41U2, 41V1, 41V2, 41W1,41W2...connect plate, 42...sensor magnet, 43U...U-phase power line, 43V...V-phase power line, 43W...W-phase power line, 44...through hole, 45...stator, 46...motor connection circuit, 47...inverter circuit, 48...resistor, 49...switching element, 50...fan, 51...right bearing, 52...winding transmission mechanism, 53...reduction mechanism, 55...iron core (magnetic core), 56...relay coil, 58...leaf spring, 59...movable contact, 60...fixed contact, 62...yoke portion, 63...teeth portion, 67U...U-phase power line connection portion, 67V...V-phase power line connection connection portion, 67W...W-phase power line connection portion, 71...current detection circuit, 72...voltage detection circuit, 73...operation amount detection circuit, 74...temperature detection circuit, 75...thermistor (temperature detection element), 76...rotor position detection circuit, 77...rotation speed detection circuit, 78...relay drive circuit, 79...control signal output circuit, 80...arithmetic unit (control unit), 81...control circuit power supply, 82...36V step-down circuit (first step-down circuit), 83...24V step-down circuit (first step-down circuit or second step-down circuit), 84...Hall IC signal detection circuit, 85...delta side relay switching circuit, 86...Y side relay switching Circuit, 87...ground pattern, 88...panel board, 89...battery terminal board, 90...12V step-down circuit (second step-down circuit), 91...first conductive pattern, 92...second conductive pattern, 93...third conductive pattern, 94...fourth conductive pattern, 95...fifth conductive pattern, 96...sixth conductive pattern, 98...12V step-down circuit, 99...12V step-down circuit, 101...first conductive pattern, 102...second conductive pattern, 103...third conductive pattern, 104...fourth conductive pattern, 105...fifth conductive pattern, 106...sixth conductive pattern, 107...ground pattern, 123...inverter board, 127...stator board, 201...first conductive pattern, 202...second conductive pattern, 203...third conductive pattern, 204...fourth conductive pattern, 205...fifth conductive pattern, 206...sixth conductive pattern, 223...inverter board, 227...stator board, 327...stator board, 427...stator board, 527...stator board, RY1 to RY7...relay, U1 to U3...U-phase stator coil, V1 to V3...V-phase stator coil, W1 to W3...W-phase stator coil.

Claims

1. a motor having a stator including a plurality of windings; a drive unit that drives the motor; a plurality of relays capable of switching the connection method of the plurality of windings between a delta connection and a star connection; a second substrate on which the plurality of relays are mounted; a plurality of power supply lines that electrically connect the second substrate and the drive unit and serve as power supply paths from the drive unit to the plurality of windings; A work machine having the second substrate is disposed at one end of the stator in the axial direction of the motor, and has a plurality of power supply connection portions to which the plurality of power supply lines are respectively connected; the plurality of power supply line connection portions are spaced apart from one another in a circumferential direction of the motor, At least one relay among the plurality of relays is located between the plurality of power supply line connection portions in the circumferential direction. A work machine characterized by:

2. The work machine according to claim 1, The plurality of relays include: a first relay that is turned on when the wiring method is a delta connection; a second relay that is turned on when the wiring method is a star connection, the first relays and the second relays are arranged alternately in the circumferential direction; A work machine characterized by:

3. The work machine according to claim 1, a first substrate on which the drive unit is mounted; a step-down circuit that steps down an externally supplied power supply voltage and supplies the stepped-down voltage to each coil of the plurality of relays; the step-down circuit is disposed on the first substrate; A work machine characterized by:

4. The work machine according to claim 1, The plurality of relays include: a plurality of first relays that are turned on when the wiring method is a delta connection; a plurality of second relays that are turned on when the wiring method is a star connection; the coils of the plurality of first relays are connected in series with one another; the coils of the plurality of second relays are connected in series with each other; A work machine characterized by:

5. The work machine according to claim 4, the number of the plurality of first relays is three, the number of the plurality of second relays is two, a first step-down circuit that steps down an externally supplied power supply voltage and supplies the stepped-down voltage to each coil of the plurality of first relays; a second step-down circuit that steps down the power supply voltage and supplies the step-down voltage to each coil of the plurality of second relays, the second step-down circuit having a step-down rate higher than that of the first step-down circuit; A work machine characterized by:

6. The work machine according to claim 1, the second substrate includes a number of conductive layers and has a plurality of conductive patterns that electrically connect the plurality of power supply line connection portions and the plurality of relays; Conductive patterns electrically connecting any one of the power supply line connection portions and any one of the relays are provided across two or more layers of the second substrate, overlapping and electrically connected to each other. A work machine characterized by:

7. The work machine according to claim 6, a plurality of connect plates electrically connecting the plurality of windings and the second substrate; the second substrate has a plurality of conductive patterns that electrically connect the plurality of connect plates and the plurality of relays; Conductive patterns electrically connecting any one of the connect plates and any one of the relays are provided across two or more layers of the second substrate, overlapping and electrically connected to each other. A work machine characterized by:

8. The work machine according to claim 7, the plurality of conductive patterns electrically connecting the plurality of connect plates and the plurality of relays include a conductive pattern connected to two of the plurality of relays and a conductive pattern connected to three of the plurality of relays; A work machine characterized by:

9. The work machine according to claim 1, the second substrate has a plurality of power supply line connection portions to which the plurality of power supply lines are respectively connected; the second substrate is composed of a number of conductive layers including a first layer provided with a large current conductive pattern that electrically connects the plurality of power supply line connection portions and the plurality of relays, and a second layer provided with a signal conductive pattern different from the large current conductive pattern. A work machine characterized by:

10. The work machine according to claim 9, the large current conductive patterns are provided across two or more layers including the first layer of the second substrate, overlapping and electrically connected to each other; A work machine characterized by:

11. The work machine according to claim 1, two relays among the plurality of relays are a relay whose longitudinal direction is substantially parallel to a radial direction of the motor, and a relay whose longitudinal direction is substantially parallel to a circumferential direction of the motor, and are adjacent to each other in the circumferential direction; A work machine characterized by:

12. A work machine as described in claim 1, a step-down circuit that steps down an externally supplied power supply voltage and supplies the step-down voltage to each coil of the plurality of relays; the step-down circuit is disposed on the second substrate; A work machine characterized by:

13. A work machine as described in claim 1, a step-down circuit for stepping down a power supply voltage supplied from an external device; The plurality of relays include: a plurality of first relays that are turned on when the wiring method is a delta connection; a plurality of second relays that are turned on when the wiring method is a star connection; At least one coil of the plurality of first relays and at least one coil of the plurality of second relays receive power from the common step-down circuit. A work machine characterized by:

14. A work machine as described in claim 1, The plurality of relays include: three first relays that are turned on when the wiring method is a delta connection; two second relays that are turned on when the wiring method is a star connection; coils of two of the three first relays are connected in series with each other; a coil of the remaining one of the three first relays is connected in parallel to the coils of the two first relays of the three first relays; The coils of the two second relays are connected in series with each other. A work machine characterized by:

15. A work machine as described in claim 1, The plurality of relays include: three first relays that are turned on when the wiring method is a delta connection; two second relays that are turned on when the wiring method is a star connection; The coils of the three first relays are connected in parallel with each other, The coils of the two second relays are connected in parallel with each other. A work machine characterized by: