Rotating rectifier, rotating electric machine, and rotating electric machine system for dump truck

Abstract

To provide a rotary rectifier, a rotary electric machine, and a rotary electric machine system for dump trucks that reduce the number of parts and cost and save space as a shaft voltage countermeasure for excitation type rotary electric machines when an AC exciter system is used.SOLUTION: There is provided a rotary rectifier comprising a shaft rotatably supported by a frame, an AC exciter that is fixed to the shaft and rotates, a slip ring that is fixed to the shaft and rotates, and is equipped with an element that rectifies the current output from the AC exciter, and a carbon brush that slides against the slip ring at the radial end of the slip ring. In the rotary rectifier, insulating layers are provided on both axial sides of the slip ring, the elements are circumferentially arranged on one axial side of the slip ring, and the insulating layers are provided and fastened between the element fastening parts and the slip ring.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a rotary rectifier, a rotating electric machine, and a rotating electric machine system for a dump truck. [Background technology]

[0002] In recent years, in order to reduce greenhouse gas emissions, electric drive systems have been adopted for railroad cars, construction vehicles, etc., instead of the conventional system that uses diesel engines as a power source. In the case of electric drive, the power source that supplies electricity is a diesel generator, which is more fuel efficient and improves system efficiency than when driven by a diesel engine itself.

[0003] Excitation type rotating electric machines are widely used in engine generators. In the case of excitation type, the rotor can be controlled by passing an excitation current directly through it, so it is possible to operate with a power factor of 1.0, and it is more efficient than an induction rotating electric machine. However, in the case of excitation type, a power supply device is required to excite the rotor. There are two types of power supply device: the brush type, which uses brushes and slip rings, and the AC exciter type, which can pass excitation current without contact by passing direct current to the stator side and providing a three-phase winding on the rotor.

[0004] The diesel generators used in the above-mentioned railroads and construction vehicles also have different configurations depending on the application. In particular, construction vehicles require specific operations when the vehicle is stopped. For example, in the case of a dump truck, the operation is to unload the soil loaded on the truck bed. At this time, the bed is operated by the power of a hydraulic pump to provide an incline to the bed.

[0005] This hydraulic pump mechanism is called PTO (Power Take Off), and is driven by the idling engine when the truck is stopped. In the case of trucks equipped with diesel generators, engine power during idling is supplied to the PTO via the generator. In other words, from the generator's perspective, the engine, which is the main power source, is directly connected to the generator at the end of the shaft, and the PTO is directly connected to the opposite end of the shaft. This is a configuration unique to construction vehicles.

[0006] With this configuration, the problem of shaft voltage occurs in the above-mentioned power supply method. In regard to this point, when the brush method is used, the slip ring and the shaft are electrically connected and an earth brush separate from the excitation is provided, so that the shaft voltage can be discharged to the ground and electrolytic corrosion of the generator and PTO bearings can be prevented.

[0007] On the other hand, when using the AC exciter method, it is necessary to consider measures against shaft voltage. Although it is possible to provide earth brushes with the AC exciter method, this requires that the AC exciter, slip ring, earth brushes, and a rectifier circuit for rectifying the current from the AC exciter be laid out on the rotating shaft in addition to the generator itself, which increases the number of parts and costs, and requires space for placement. Another method is to use ceramic bearings to prevent current from flowing, but this significantly increases costs.

[0008] For this reason, configurations using an AC exciter system have been considered. For example, Patent Document 1 illustrates a generator that uses the AC exciter system, in which an ignition signal to the rectifier circuit is received from a control device outside the generator via a slip ring to control the rotor field current. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2018-074885 A Summary of the Invention [Problem to be solved by the invention]

[0010] Although not shown in Patent Document 1, the ignition signal for controlling the rectifier circuit is received inside the rotor using slip rings and carbon brushes. If each part is arranged inside the generator in this configuration, the AC exciter, receiving device (slip rings, carbon brushes), and rectifier circuit will be arranged in a row on the rotating shaft. This increases the size of the generator, leading to an increase in the number of parts that make up each part and an increase in cost. In addition, no measures are taken against the shaft voltage, which was mentioned as an issue above. Since it is not shown in the drawings of Patent Document 1, it is thought that a ceramic bearing is applied as a measure against the shaft voltage. For the above reasons, problems with the number of parts, cost, and space become apparent.

[0011] In view of the above, an object of the present invention is to provide a rotating rectifier, a rotating electric machine, and a rotating electric machine system for dump trucks that reduce the number of parts and costs and achieve space savings as a countermeasure against shaft voltage in an excitation type rotating electric machine when an AC exciter method is used. [Means for solving the problem]

[0012] In view of the above, the present invention is described as "a rotary rectifier comprising a shaft rotatably supported on a frame, an AC exciter fixed to the shaft and rotating, a slip ring fixed to the shaft and rotating and equipped with an element that rectifies the current output from the AC exciter, and carbon brushes that slide against the slip ring at the radial end of the slip ring, with insulating layers provided on both axial sides of the slip ring, elements arranged circumferentially on one axial side of the slip ring, and fastened with an insulating layer provided between the fastening parts of the element and the slip ring."

[0013] In addition, the present invention is defined as "a rotating electric machine characterized by comprising a rotating rectifier, a rotor fixed to a shaft and rotating, and a stator arranged at a position on the frame side opposite the rotor."

[0014] In addition, the present invention is described as "a rotating electric machine system for a dump truck which includes a rotating electric machine, an engine, a converter, and a blower for cooling the rotating electric machine, and which generates electricity using the rotating electric machine when driven by the engine, and supplies the electricity via the converter." Effect of the Invention

[0015] According to the present invention, it is possible to discharge the shaft voltage that occurs when an AC exciter method is used, reduce the number of parts and costs, and realize space saving. [Brief description of the drawings]

[0016] [Figure 1] 1 is an axial cross-sectional view of a rotating electric machine including a rotary rectifier according to an embodiment of the present invention; [Diagram 2] 1 / 10, A-A' cross-sectional view of AC exciter 2 shown in Figure 1. [Diagram 3] 2 is a 1 / 10 cross-sectional view taken along the line B-B' of the excitation type rotating electric machine 3 shown in FIG. 1. [Figure 4] FIG. 2 is a diagram showing a configuration example of a rectifier circuit according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram showing a configuration example of a rectifier circuit according to an embodiment of the present invention. [Figure 6] FIG. 4 is a diagram showing the direction of current flowing through an element 41 and the direction in which centrifugal force is applied. [Figure 7] FIG. 4 is a diagram showing stress applied to a connection portion inside an element 41 due to centrifugal force. [Figure 8] FIG. 1 is a diagram showing factors that cause wear of a carbon brush. [Figure 9] FIG. 6 is a cross-sectional view of a slip ring 6 according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a diagram showing an example of an element attachment according to a second embodiment of the present invention. [Figure 11] FIG. 11 is an enlarged view of a rectifier circuit 39 according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a cross-sectional view of a rectifier circuit 39 according to a third embodiment of the present invention. [Figure 13] FIG. 11 is a diagram showing the positions at which ventilation holes 49 are provided according to the third embodiment of the present invention. [Figure 14] FIG. 11 is an enlarged view of a slip ring 6 and a carbon brush 7 according to a fourth embodiment of the present invention. [Figure 15] FIG. 11 is a diagram showing a rectifier circuit 39 according to a fifth embodiment of the present invention as viewed from the axial direction. [Figure 16] FIG. 13 is an enlarged view of a slip ring 6 and a carbon brush 7 according to a sixth embodiment of the present invention. [Figure 17] FIG. 13 is a diagram showing an example in which the present invention is applied to an excitation type rotating electric machine system for a dump truck according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same parts are given the same numbers. EXAMPLES

[0018] Fig. 1 is an axial cross-sectional view of a rotating electric machine equipped with a rotary rectifier according to an embodiment of the present invention. This rotating electric machine is equipped with a rotary rectifier that is mainly used in connection with an engine. The rotating electric machine has a rotation speed of several thousand min-1 and is used as a power source for large dump trucks.

[0019] 1 is configured by arranging an AC exciter 2 (AC exciter) and an excitation type rotating electric machine 3 on the same axis (shaft 12) within a frame 1. In addition to a rotor 13 and a stator 14, the AC exciter 2 has slip rings 6, carbon brushes 7, a brush holder 46, and a rod 47 arranged in the vicinity thereof.

[0020] The excitation type rotating electric machine 3 is composed of a rotor 4 and a stator 5, and rotor coil end 8 and stator coil end 9, 10 protrude from the axial ends of the rotor 4 and the stator 5. Bearings 11 are provided on the frame 1 to rotate the rotor 4 and rotor 13. In this figure, as mentioned above, the rotor is connected to the engine, so the side without bearing 11 is supported by a bearing on the engine side. Of course, there is no problem if bearings 11 are provided on both sides of the rotating electric machine 100. The rotor 13 and rotor 4 of the AC exciter 2 are fastened to the shaft 12.

[0021] Also, in the frame 1 in the figure, an inlet 15 through which a coolant flows in is arranged. As will be described later, coolant 16 entering the inlet 15 is sent by a blower 301 (described later using FIG. 17) arranged separately from the rotating electric machine 100. The coolant 16 flows from the inlet 15 to the right in FIG. 1 and flows out to the atmosphere (open).

[0022] Fig. 2 is a 1 / 10 (one of the 10 divided poles) A-A' cross-sectional view of the AC exciter 2 shown in Fig. 1. As shown in the figure, the rotor 13 and stator 14 of the AC exciter 2 are composed of a field core 17, an armature core 18, a field coil 19, an armature coil 20, and a gap 21 as main components.

[0023] The field coil 19 is wound in a concentrated manner in the field slots 22, and a direct current is supplied to the field coil 19 from a power source separate from the rotating electric machine 100. Meanwhile, the armature core 18 is fastened to the shaft 12 and rotates. The armature coil 20 is wound in a distributed manner in the armature slots 23, and three-phase alternating current is output. An axial duct 24 for flowing the refrigerant 16 in the axial direction is provided on the inner diameter side of the armature core 18. The field core 17 is fixed to the frame 1, and the fixed parts are fixed at predetermined intervals in the circumferential direction, and a back duct 25 for flowing the refrigerant 16 in the axial direction is provided between the fixed parts.

[0024] Fig. 3 is a 1 / 10 (one of the 10 divided poles) B-B' cross-sectional view of the excitation type rotating electric machine 3 shown in Fig. 1. As shown in the figure, the rotor 4 and stator 5 of the excitation type rotating electric machine 3 are composed of a rotor core 26, a stator core 27, a field coil 28, a main stator coil 29, an auxiliary stator coil 30, a gap 31, a damper bar 32, a rotor wedge 33, and a stator wedge 34 as main components.

[0025] The field coil 28 is wound in a concentrated manner in the rotor slots 35, and a direct current is supplied to the field coil 28 as an excitation current. Details of this excitation current will be described later. Meanwhile, the stator main coil 29 and the stator auxiliary coil 30 are wound in a distributed manner in the stator slots 36, and each outputs three-phase alternating current as generated power. The stator main coil 29 outputs power for the dump truck to run, and the stator auxiliary coil 30 outputs power for the dump truck's system power supply (lights, air conditioner, blower, etc.). For this reason, the specifications (generated power output, voltage, current) are different due to the different applications, and the stator main coil 29 and the stator auxiliary coil 30 have different coil cross-sectional areas and numbers of coil turns.

[0026] An axial duct 37 for flowing the refrigerant 16 in the axial direction is provided on the inner diameter side of the rotor core 26. The fixed parts of the stator 5 and the frame 1 are fixed at a predetermined interval in the circumferential direction, and a back duct 38 for flowing the refrigerant 16 in the axial direction is provided between the fixed parts. Therefore, the refrigerant 16 flows through the slip ring 6 and the ventilation path of the AC exciter 2 (gap 21, axial duct 24, back duct 25), passes through the ventilation path of the excitation type rotating electric machine 3 (gap 31, axial duct 37, back duct 38) and is released to the atmosphere.

[0027] As explained in the background art, the slip rings 6 and carbon brushes 7 are arranged to discharge the shaft voltage, but a direct current is required to be supplied to the field coil 28. For this purpose, a rectifier circuit is required.

[0028] In other words, the order of current supply to the field coil 28 is as follows: DC current is supplied from an external power source to the field coil 19 of the AC exciter 2, and as the armature coil 20 rotates, AC current is generated in the armature coil 20. This AC current is then converted to DC by the rectifier circuit and supplied to the field coil 28.

[0029] 4 and 5 show configuration examples of a rectifier circuit according to an embodiment of the present invention. Fig. 4 is an enlarged view of a slip ring 6, carbon brushes 7, and a rectifier circuit 39. As shown in Fig. 4, carbon brushes 7 are in contact with the outer periphery of the slip ring 6. Insulating layers 40 are arranged on both axial side surfaces of the slip ring 6, and a rectifying element 41 and a bracket 42 for fixing the element 41 are arranged on one side and fastened with bolts 43.

[0030] Fig. 5 is a front view in the axial direction of Fig. 4. It shows the configuration when the slip ring 6 is viewed from the left side of Fig. 4, which is the surface side on which the rectifying elements 41 are arranged. As described above, since the output current from the AC exciter 2 is a three-phase AC output, it becomes a three-phase full-wave rectifier circuit, and the elements 41 are arranged in six places.

[0031] In this case, the elements 41 are arranged, for example, at equal angles in the circumferential direction on the surface of the slip ring 6, and arranged so that the electrodes 41a of the elements 41 are on the axial side in the circumferential direction. For this reason, one surface 42a of a bracket 42 for fixing the L-shaped element 41 is fastened with a bolt 43a via an insulating layer 40 on the axial side surface of the slip ring 6, and the element 41 is fastened and fixed with a nut 45 at the axially distal end in the circumferential direction on the other surface 42b of the bracket 42.

[0032] The electrodes 41a of the element 41 are connected to three-phase AC from the AC exciter 2, and are connected as the positive and negative poles of the field coil 28. The reason why the insulating layers 40 are provided on both axial sides of the slip ring 6 is to insulate the slip ring 6 and the carbon brushes 7 as an electric circuit that discharges the axial voltage from the rectifier circuit 39. This eliminates the need to provide a separate component for configuring the rectifier circuit 39, thereby reducing the number of components and costs, saving space, and enabling the axial voltage to be discharged reliably.

[0033] 5, the circuit configuration can be simplified by arranging the positive and negative poles of element 41 in the upper and lower halves of the figure with the above-mentioned polarity. As shown in the figure, the output sides of element 41 (terminals connected to field coil 28: electrode 41a side) can be consolidated and connected to positive and negative terminal blocks 44, respectively. In this way, it is possible to reduce the number of lead wires to be connected to field coil 28, and further, since terminal block 44 is arranged on the rotor inner diameter side, the wiring work to be connected to field coil 28 can also be reduced. This is because the wiring to be connected to field coil 28 is routed inside shaft 12.

[0034] It is effective to arrange element 41 so that the direction of the current flowing through element 41 and the direction in which centrifugal force Fc is applied are aligned as shown in Fig. 6. Inside element 41, the semiconductor (element 41) and terminal (electrode 41a) are connected by soldering or the like in the direction in which the current flows. For this reason, if the element 41 is arranged so that the direction of the centrifugal force and the direction in which the current flows are perpendicular to each other, the connection part inside element 41 will be broken by the centrifugal force.

[0035] 6, element 41 is fixed to bracket 42 with nuts 45. In the figure, element 41 is fixed on the outer diameter side of element 41 with nuts 45. The reason for this is that, as shown in FIG. 7, the stress applied to the internal connection part of element 41 due to centrifugal force is compressive stress.

[0036] If the stress is compressive, fatigue failure due to the stress amplitude will not occur, so the arrangement shown in Fig. 7 is optimal for ensuring the reliability of element 41. If nut 45 of the fastening part were placed on the inner diameter side (element 41 in Fig. 6 rotated 180°), the internal stress would become tensile, resulting in fatigue failure.

[0037] Since element 41 is always in a powered state and generates heat, it is necessary to cool element 41. Regarding the cooling surface, as shown in Fig. 1, coolant 16 flows from the left end of Fig. 1. In other words, by arranging element 41 on the surface through which coolant 16 flows, element 41 can be effectively cooled.

[0038] Here, the characteristics of the carbon brush 7 will be explained. Normally, the carbon brush 7 is a consumable item that wears out and therefore requires periodic replacement. Figure 8 shows the causes of carbon brush wear. As shown in Figure 8, with the horizontal axis representing current density and the vertical axis representing brush wear amount, brush wear can be classified into electrical wear and mechanical wear, and generally, electrical wear is the dominant cause of carbon brush wear. This means that wear occurs due to the constant flow of current to excite the brush.

[0039] In this regard, in the application of the present invention, since the purpose is to discharge the shaft voltage, no steady current flows, and even if it does flow, it is extremely small, so it can be said that there is almost no electrical wear. Therefore, mechanical factors are the dominant cause of wear. Furthermore, after the carbon brush is manufactured, it is not installed in the product as it is, but is subjected to a break-in process to form a contact surface with the slip ring. This break-in process stage corresponds to the mechanical wear shown in Figure 8. In other words, after the break-in process and installation in the product, there is almost no wear of the carbon brush due to actual operation. Therefore, there is almost no need to replace the carbon brush, so it is possible to maintain the effect of reducing maintenance, which is an advantage of the AC exciter method.

[0040] In this embodiment, the AC exciter 2 has 10 poles, the stator 14 has 60 slots, and the excitation type rotating electric machine 3 has 10 poles and the stator 5 has 90 slots, but the effects of the present invention can be obtained with other numbers of poles and slots. Also, although the rotor shape of the excitation type rotating electric machine 3 is cylindrical, a salient pole rotor shape may be used without any problem. Furthermore, the excitation type rotating electric machine 3 has a coil configuration of the stator 5 so that it can output two systems of generated power, but it may also be a single system without any problem.

[0041] However, in the case of a dump truck or the like, where two power systems are required, one for driving and one for system power, two generators are required: a main generator (for driving) and an auxiliary generator (for system power). In this case, one more generator is added in the axial direction. For this reason, in the case of a power generation system having two power systems from the viewpoints of reducing the number of parts, costs, and space, applying the present invention to a generator with a double-winding stator as in this embodiment will result in a power generation system in which the effects of the present invention can be more effectively exhibited. EXAMPLES

[0042] Fig. 9 is a cross-sectional view of a slip ring 6 according to a second embodiment of the present invention. As shown in Fig. 9, recesses 48 are provided on both axial side surfaces of the slip ring 6. As shown in the first embodiment, an insulating layer 40 is provided on the axial side surface of the slip ring 6. When an insulating material such as Bakelite is disposed in this insulating layer 40, the provision of recesses 48 serves as a spigot portion, facilitating positioning and improving productivity.

[0043] In addition, when molding the insulating layer 40 by hardening a liquid material such as epoxy or varnish, the recess 48 serves as a tray, making it possible to mold the insulating layer accurately in the desired location, which also leads to improved productivity.

[0044] Fig. 10 is an example of an element attachment according to Example 2 of the present invention. From the viewpoint of improving productivity, it is also effective to arrange the bolts 43 of the bracket 42, which attaches the element 41, in the circumferential direction and on the inner diameter side of the element 41, as shown in Fig. 10. This makes it easier to work because the tool for fastening the bolts 43 is less likely to interfere with the element 41, thereby improving productivity. EXAMPLES

[0045] 11 and 12 are an enlarged view and a cross-sectional view of a rectifier circuit 39 according to a third embodiment of the present invention. As shown in Fig. 11, a plurality of ventilation holes 49 are provided in the circumferential direction on the axial side surface of the slip ring 6 and on the insulating layer 40. By providing the ventilation holes 49, the refrigerant 16 can easily flow in the axial direction as shown in Fig. 12, so that the refrigerant flow rate of the AC exciter 14 and the excited rotating electric machine 4, which are located downstream of the rectifier circuit 39 with respect to the inlet of the refrigerant 16, is increased, and the cooling performance is improved.

[0046] Fig. 13 is a diagram showing the position of providing ventilation holes 49 according to the third embodiment of the present invention. On the other hand, as shown in Fig. 13, ventilation holes 49 may be provided on bracket 42, which is located immediately adjacent to element 41, without any problem (element 41 is not shown). In this case, refrigerant 16 passes through element 41 and ventilation holes 49, which is effective for actively cooling element 41. EXAMPLES

[0047] Fig. 14 is an enlarged view of the slip ring 6 and the carbon brush 7 according to the fourth embodiment of the present invention. As shown in Fig. 14, the axial width of the slip ring 6 is made larger than the axial width of the carbon brush 7. By making the axial width of the slip ring 6 larger, it is possible to ensure contact between the slip ring 6 and the carbon brush 7 even in the event of misalignment due to axial vibration of the carbon brush 7 or uneven assembly. In addition, since the surface area of ​​the slip ring itself is increased, the heat transfer area of ​​the refrigerant 16 is also increased, thereby improving the cooling performance. EXAMPLES

[0048] 15 is a view of a rectifier circuit 39 according to a fifth embodiment of the present invention as viewed from the axial direction. In the first to fourth embodiments, the carbon brushes 7 and the brush holders 46 are disposed in the circumferential direction directly below the surface of the paper.

[0049] In FIG. 15, the carbon brush 7 and the brush holder 46 are arranged between 6 o'clock and 9 o'clock. For example, if they are arranged directly below 6 o'clock, it is difficult to visually check the carbon brush 7 when inspecting or replacing it, and the replacement work is also difficult. If they are arranged at positions shifted in the circumferential direction as shown in FIG. 14 and a window for inspection and brush replacement is provided in the frame 1 at the 6 o'clock to 9 o'clock positions in the same figure, it becomes easier to visually check the entire brush and brush holder during maintenance, and the workability of brush replacement is also improved. In this embodiment, the positions are between 6 o'clock and 9 o'clock, but the same effect can be obtained if they are located at any position other than directly below or directly above, such as between 12 o'clock and 6 o'clock or between 6 o'clock and 12 o'clock. EXAMPLES

[0050] Fig. 16 is an enlarged view of a slip ring 6 and a carbon brush 7 according to a sixth embodiment of the present invention. As shown in Fig. 16, a groove 50 is provided in a spiral shape on the outer circumferential surface of the slip ring 6. By providing the groove 50 in a spiral shape, it is possible to equalize the imbalance of current on the contact surface of the carbon brush 7. In addition, since the groove 50 is provided on the contact surface, the cooling performance of the contact portion is also improved. EXAMPLES

[0051] Fig. 17 shows an example in which the present invention is applied to an excitation type rotating electric machine system for a dump truck according to a seventh embodiment. As shown in Fig. 17, the excitation type rotating electric machine 100 according to the first to sixth embodiments is directly connected to an engine 200 via a coupling 60. When the engine 200 is driven, power is supplied from the excitation type rotating electric machine 100 to power converters 201a and 201b. The power converter 201a supplies power to a driving rotating electric machine 300 of the dump truck. On the other hand, the power converter 201b supplies power as power for auxiliary equipment such as a blower 301 that circulates a refrigerant 16 for cooling the rotating electric machine 100. [Explanation of symbols]

[0052] 1: frame, 2: AC exciter, 3: excitation type rotating motor, 4: rotor (excitation type rotating motor), 5: stator (excitation type rotating motor), 6: slip ring, 7: carbon brush, 8: rotor coil end, 9, 10: stator coil end, 11: bearing, 12: shaft, 13: rotor (AC exciter), 14: stator (AC exciter), 15: inlet, 16: refrigerant 17: field core, 18: armature core, 19, 28: field coil, 20: armature coil, 21, 31: gap, 22: field slot, 23: armature slot, 24, 37: axial duct, 25, 38: rear duct, 26: rotor core, 27: stator core, 29: main stator coil, 30: auxiliary stator coil, 32: damper bar, 33: rotor wedge, 34: stator wedge 35: rotor slot, 36: stator slot, 39: rectifier circuit, 40: insulating layer, 41: element, 42: bracket, 43: bolt, 44: terminal, 45: nut, 46: brush holder, 47: rod, 48: recess, 49: ventilation hole, 50: groove, 60: coupling, 100: rotating electric machine, 200: engine, 201a, 201b power converter, 202: reducer, 203a, 203b: power converter, 300: driving rotating electric machine, 301: blower

Claims

1. The motor comprises a shaft rotatably supported by a frame, an AC exciter fixed to the shaft and rotating, a slip ring fixed to the shaft and rotating, and having an element for rectifying a current output from the AC exciter, and a carbon brush sliding against the slip ring at a radial end of the slip ring, A rotary rectifier characterized in that an insulating layer is provided on both axial sides of the slip ring, the element is arranged circumferentially on one axial side of the slip ring, and an insulating layer is provided between the fastening parts of the element and the slip ring to fasten them together.

2. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that the element arranged circumferentially on one axial surface of the slip ring has its electrode side oriented in the axial direction and its non-electrode side fastened to the slip ring by the L-shaped fastening part.

3. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that, for an even number of elements arranged circumferentially on one axial face of the slip ring, the elements connected to the positive pole of a rectifier circuit are arranged in half the circumferential area of ​​the slip ring, and the elements connected to the negative pole are arranged in the remaining half of the circumferential area of ​​the slip ring.

4. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that the elements are arranged so that when the direction of current flowing through the elements is connected to the center of the slip ring, a straight line is formed.

5. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that the element is disposed on an axial side surface of the slip ring on an inlet surface of the refrigerant.

6. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that a recess is provided on a side surface of the slip ring in the axial direction.

7. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that ventilation holes are provided on the axial side surfaces of the slip rings.

8. 2. The rotary rectifier of claim 1, 13. A rotary rectifier comprising: a slip ring having a brush contact area having an axial width greater than an axial width of the brush;

9. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that the circumferential arrangement of brushes is inclined with respect to the ground.

10. 2. The rotary rectifier of claim 1, A rotary rectifier characterized in that a plurality of grooves are provided in the axial direction on the surface of the slip ring with which the brushes come into contact.

11. 11. A rotating electric machine comprising: the rotary rectifier according to claim 1; a rotor fixed to the shaft and rotating; and a stator disposed on a frame side opposite to the rotor.

12. 12. A rotating electric machine system for a dump truck, comprising the rotating electric machine according to claim 11, an engine, a converter, and a blower for cooling the rotating electric machine, the rotating electric machine generating electricity by being driven by the engine, and supplying the electricity via the converter.

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