Electrical conductor bending method and apparatus

A control device moves a split claw (11) holding a projecting portion (4d) of an eighth-layer coil segment (4) in a counterclockwise direction D1. At this time, the control device moves first to third extended blades (13a) to (13c) in an outward direction D3 so that the projecting portion (4d) of the eighth-layer coil segment (4) is bent in the outward direction D3. Then, the control device moves the first to third extended blades (13a) to (13c) in an inward direction D4. Through the above steps, the projecting portion (4d) of the eighth-layer coil segment (4) is bent in the counterclockwise direction D1 while being bent in the outward direction D3. As a result, a return force tending to return in the inward direction D4 is generated by an elastic deformation force.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an electrical conductor bending method and apparatus.

Description of the Related Art

The rotary electric machine such as an electric motor and a generator comprises a stator formed in a cylindrical shape and a rotor rotatably disposed inside the stator.

A coil is formed in such a way that a leg portion of a U-shaped coil segment is inserted into a slot provided in a stator core of the stator, and then a projecting portion thereof is bent in a circumferential direction, and then the distal end portions of the mutually adjacent projecting portions are welded (for example, see Japanese Patent No. 3786059).

In the coil, since the distal end portions of the projecting portions of a pair of coil segments are welded, the projecting portions are preferably close to each other so as to facilitate welding. However, the coil disclosed in Patent Literature 1 has a difficulty in welding because the projecting portions are bent only in the circumferential direction, which increases the distance between the projecting portions of the pair of coil segments.

SUMMARY OF THE INVENTION

An object of the present invention, which has been made in view of the above circumstances, is to provide an electrical conductor bending method and apparatus for bending an electrical conductor so as to facilitate welding.

An electrical conductor bending method of the present invention is an electrical conductor bending method, in which a leg portion of each of a pair of electrical conductors formed in a U-shape and arranged in a radial direction of an annular shaped stator core is inserted into each of a plurality of slots provided on a circumference of the stator core, a projecting portion of the leg portion projecting from the slot is held by a holding member, the holding member holding the projecting portion is moved in a circumferential direction of the stator core, and thereby the projecting portion is bent in the circumferential direction, wherein

the method comprises a bending step of, while applying a stress in an outward direction of the radial direction by pressing a pressure member against one of projecting portions disposed outside the radial direction of the pair of electrical conductors, moving the holding member holding the one of the projecting portions in the circumferential direction to thereby bend the one of the projecting portions in the circumferential direction.

According to the present invention, while applying a stress in an outward direction of the radial direction to the projecting portion of one leg portion disposed outside the radial direction, the projecting portion of the one leg portion is bent in the circumferential direction, and thus a return force (spring back) tending to return in an inward direction is generated by an elastic deformation force in the projecting portion of the one leg portion after bending process. Therefore, the return force facilitates clamping for welding since the projecting portion of the one leg portion (outside) is close to the projecting portion of the other leg portion (inside) in comparison with the method without a return force.

Further, it is preferable that in the bending step, the pressure member applies the stress in the outward direction of the radial direction to a root portion of the one of the projecting portions.

According to this configuration, when a stress in the outward direction of the radial direction is applied to the projecting portion of the leg portion by moving the pressure member in the radial direction, the projecting portion can be greatly bent in the outward direction of the radial direction by a small moving distance.

Further, it is preferable that a plurality of electrical conductor units each having at least one of the pair of electrical conductors are inserted into the same slot so as to require a clearance at a boundary therebetween in the radial direction, and in the bending step, the projecting portion of the electrical conductor disposed at the outermost position in the radial direction of the electrical conductor units other than the electrical conductor units located at the outermost position in the radial direction of the plurality of electrical conductor units is bent.

According to this configuration, a return force tending to return in an inward direction is generated in the projecting portion of the electrical conductor disposed at the outermost position in the radial direction of the electrical conductor units other than the electrical conductor units located at the outermost position in the radial direction of the plurality of electrical conductor units, and thus the projecting portion does not contact the electrical conductor unit located outside in the radial direction. This can insulate the adjacent units from each other.

An electrical conductor bending apparatus of the present invention is an electrical conductor bending apparatus, in which a leg portion of each of a pair of electrical conductors formed in a U-shape and arranged in a radial direction of an annular shaped stator core is inserted into each of a plurality of slots provided on a circumference of the stator core, and a projecting portion of the leg portion projecting from the slot is bent in a circumferential direction of the stator core,

the electrical conductor bending apparatus comprising: a holding member configured to hold the projecting portion of the pair of electrical conductors, a first moving mechanism configured to move the holding member in the circumferential direction of the stator core; a pressure member configured to press one of the projecting portions disposed outside in the radial direction of the pair of electrical conductors and thereby applying a stress in an outward direction of the radial direction, a second moving mechanism configured to move the pressure member in the radial direction; and a control device configured to control driving of the first moving mechanism and the second moving mechanism, wherein

the control device performs a pressure control such that the second moving mechanism is driven to move the pressure member outward in the radial direction to press against the one of the projecting portions, and thereby a stress is applied in an outward direction of the radial direction, and at the same time, performs a bending control such that the first moving mechanism is driven to move the holding member holding the one of the projecting portions in the circumferential direction, and thereby the one of the projecting portions is bent in the circumferential direction.

According to this configuration, a return force tending to return in an inward direction is generated by an elastic deformation force in the projecting portion of the one leg portion after bending process. Therefore, the return force facilitates clamping for welding since the projecting portion of the one leg portion (outside) is close to the projecting portion of the other leg portion (inside) in comparison with a configuration without a return force.

Further, in the pressure member, an edge portion contacting the one of the projecting portions is preferably chamfered in an arc shape.

This configuration can prevent the projecting portion from being damaged by the pressing member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The description will start with an example of a structure of a rotary electric machine.

As illustrated inFIGS. 1 and 2, the rotary electric machine such as an electric motor and a generator comprises a stator1formed in a cylindrical shape and a rotor (unillustrated) rotatably disposed inside the stator1.

The stator1comprises a stator core2and a coil3. The stator core2has a cylindrical shape, and a plurality of slots2apassing therethrough in a rotation axis direction are provided spaced apart from each other in a circumferential direction. Each slot2ais formed such that a radial sectional shape of the stator core2radially extends from a center side of the stator core2in a radial direction, and communicates with an inner peripheral surface of the stator core2through a slit2bformed in the stator core2. Note that the slit2bmay be omitted.

The coil3is formed such that a coil segment4illustrated inFIG. 3is inserted into the slot2afrom one side and a projecting portion4dprojecting from the other side of the slot2ais bent in the circumferential direction and welded.

The coil segment4is formed such that a plurality of (four in the present embodiment) conductors (rectangular wire conductors) having a rectangular cross section are arranged in a row so as to face the wider surfaces to each other to form a single bundle in a U-shape. The coil segment4includes a pair of leg portions4aand4aand a head portion4bconnecting one end (upper end in the Figure) of the two leg portions4aand4a.

Note that the coil segment4may be any bundle formed by aligning a plurality of rectangular wires in the width direction. For example, the coil segment4may be formed such that a plurality of rectangular wires are aligned in a row such that the narrow sides face to each other.

The center of the head portion4bincludes an S-shaped portion4ccurved in an S shape in an alignment direction of the rectangular wire. The head portion4bis inclined downward from the center (center of the S-shaped portion4c) toward the two leg portions4aand4a. The leg portion4aof the coil segment4is inserted into a corresponding slot2afrom one side thereof. The leg portion4aof the coil segment4is projected from the other side of the slot2a.

As illustrated inFIG. 4A, the projecting portion4dof the leg portion4aprojecting from the other side of the slot2ais bent in a counterclockwise direction D1and a clockwise direction D2, which are the circumferential direction of the stator core2, by a bending apparatus10to be detailed later, and the distal end portions of the corresponding projecting portions4dare welded by a welding device (unillustrated). In this manner, the stator1is completed such that eight layers of (eight) coil segments4are stacked in the radial direction. Here, the coil segments4are aligned in the order of the first layer, the second layer, . . . , and the eighth layer from inside to outside in the radial direction.

In the present embodiment, the first-layer to eighth-layer coil segments4include a pair of the first layer and the second layer, a pair of the third layer and the fourth layer, a pair of the fifth layer and the sixth layer, and a pair of the seventh layer and the eighth layer. Further, the first-layer to fourth-layer coil segments are grouped into a unit (first unit), and the fifth-layer to eighth-layer coil segments are grouped in a unit (second unit).

The projecting portion4dof each of the first-layer to fourth-layer coil segments4as the first unit and the projecting portion4dof each of the fifth-layer to eighth-layer coil segments4as the second unit are inserted into the slot2aof the stator core2so as to be spaced apart from each other in the radial direction (an outward direction D3and an inward direction D4) at a boundary therebetween (a boundary between the projecting portion4dof the fourth-layer coil segment4and the projecting portion4dof the fifth-layer coil segment4).

Note that the coil3of the present embodiment is a three-phase coil including a U phase, a V phase, and a W phase. The leg portion4aof the coil segment4inserted into each slot2ahas a U phase, a U phase, a V phase, a V phase, a W phase, and a W phase arranged in that order in the circumferential direction.FIG. 4Billustrates only one-phase coil (for example, a U-phase coil) of the three-phase coil.

The description will now focus on the bending apparatus10which bends the projecting portion4dof the leg portion4ain the counterclockwise direction D1and the clockwise direction D2, which are the circumferential direction, as illustrated inFIGS. 5 to 8.

The bending apparatus10comprises a split claw11(holding member) holding the distal end portion of the projecting portion4d, and a split claw moving mechanism12(first moving mechanism) (seeFIG. 9) which comprises, for example, a motor and gears and moves the split claw11in the counterclockwise direction D1and the clockwise direction D2, and in the outward direction D3and the inward direction D4which are the radial direction, and in the axial direction. Note that the holding member holding the distal end portion of the projecting portion4dis not limited to the split claw11, but may be appropriately changed.

Further, the bending apparatus10comprises first to third extended blades13ato13c(pressure member) and a blade moving mechanism14(second moving mechanism) (seeFIG. 9) which comprises, for example, a motor and gears, and moves the first to third extended blades13ato13cin the outward direction D3and the inward direction D4which are the radial direction.

The bending apparatus10comprises a control device15(seeFIG. 9) which comprises, for example, a CPU or the like, and integrally controls the bending apparatus10. The control device15controls driving of the split claw moving mechanism12and the blade moving mechanism14. Note that the structure of the split claw moving mechanism12and the blade moving mechanism14may be appropriately changed. For example, the structure may include a mechanism having a movable lever and a cylinder or may include a robot having a movable arm.

As illustrated inFIGS. 5A to 5D and 6A to 6D, the split claw11is opened in the outward direction D3and the inward direction D4and holds the distal end portion of the projecting portion4d. In a state of holding the distal end portion of the projecting portion4d, the split claw11is moved in the counterclockwise direction D1by the split claw moving mechanism12and bends the projecting portion4din the counterclockwise direction D1while maintaining the distal end portion of the held projecting portion4din a state of being parallel to an upward direction.

When the projecting portions4dof even-number-th layers (second layer, fourth layer, sixth layer, and eighth layer) of coil segments4are bent in the counterclockwise direction D1, the first extended blade13acontacts the root portion of the bent projecting portion4d, the second extended blade13bcontacts the central portion of the bent projecting portion4d, and the third extended blade13ccontacts the distal end portion of the bent projecting portion4d. The first to third extended blades13ato13care such that the edge portions contacting the projecting portions4dare chamfered in an arc shape (for example, a circular arc shape). Note that the positions of the first to third extended blades13ato13cmay be appropriately changed and the edge portions may not be chamfered.

Note also that the pressure member pressing the projecting portion4dand thereby applying a stress is not limited to the first to third extended blades13ato13c, but may be appropriately changed. For example, the pressure member may be a mechanism having a movable lever and a cylinder or may be a robot having a movable arm.

As illustrated inFIGS. 7A, 7B, 8A, and 8B, in a state of holding the distal end portion of the projecting portion4dof odd number-th layers (first layer, third layer, fifth layer, and seventh layer) of coil segments4, the split claw11is moved in the clockwise direction D2by the split claw moving mechanism12. Thus, while maintaining the distal end portion of the held projecting portion4din a state of being parallel to an upward direction, the split claw11bends the projecting portion4din the clockwise direction D2. Note that the configuration of a pair of coil segments4is not limited to the present embodiment as long as the pair of coil segments4may be bent in opposite directions.

When the projecting portion4dis bent in the clockwise direction D2, the first extended blade13acontacts the distal end portion of the bent projecting portion4d, the second extended blade13bcontacts the central portion of the bent projecting portion4d, and the third extended blade13ccontacts the root portion of the bent projecting portion4d.

When the projecting portions4dof the coil segments4are bent using the bending apparatus10, as illustrated inFIGS. 5A and 6A, first, the control device15drives the split claw moving mechanism12to move the split claw11, thereby to cause the split claw11to hold the projecting portion4dof the eighth-layer coil segment4located at the outermost position.

Then, the control device15drives the split claw moving mechanism12to cause the split claw11holding the projecting portion4dof the eighth-layer coil segment4to move in the counterclockwise direction D1up to the position illustrated inFIGS. 5B and 6B(bending control).

When the split claw moving mechanism12is driven to move the split claw11in the counterclockwise direction D1up to the position illustrated inFIGS. 5B and 6B, the control device15drives the blade moving mechanism14(bending step). At this time, the control device15drives the blade moving mechanism14to move the first to third extended blades13ato13cin the outward direction D3so that the projecting portion4dof the eighth-layer coil segment4is bent in the outward direction D3(pressure control). According to this movement, the control device15drives the split claw moving mechanism12to move the split claw11holding the projecting portion4din the outward direction D3.

The control device15moves the split claw11in the counterclockwise direction D1from the position illustrated inFIGS. 5B and 6Bup to the position illustrated inFIGS. 5C and 6C(bending control). At this time, the control device15maintains the position in which the first to third extended blades13ato13care moved in the outward direction D3.

Then, the control device15moves the split claw11in the counterclockwise direction D1from the position illustrated inFIGS. 5C and 6Cup to the position illustrated inFIGS. 5D and 6D(bending control). At this time, the control device15drives the blade moving mechanism14to move the first to third extended blades13ato13cin the inward direction D4. According to this movement, the control device15drives the split claw moving mechanism12to move the split claw11holding the projecting portion4din the inward direction D4. Through the above steps, the projecting portion4dof the eighth-layer coil segment4is bent in the counterclockwise direction D1while being bent in the outward direction D3.

When the projecting portion4dof the seventh-layer coil segment4is bent, as illustrated inFIGS. 7A and 7B, the control device15drives the split claw moving mechanism12to move the split claw11, thereby to cause the split claw11to hold the projecting portion4dof the seventh-layer coil segment4.

Then, the control device15drives the split claw moving mechanism12to cause the split claw11holding the projecting portion4dof the seventh-layer coil segment4to move in the clockwise direction D2up to the position illustrated inFIGS. 7B and 8B. At this time, the control device15brings the first to third extended blades13ato13cat the position in which the projecting portion4dof the seventh-layer coil segment4is supported without being bent in the outward direction D3. Through the above steps, the projecting portion4dof the seventh-layer coil segment4is bent in the clockwise direction D2. As a result, as illustrated inFIG. 10, the distal end portion of the projecting portion4dof the eighth-layer coil segment4faces the distal end portion of the projecting portion4dof the seventh-layer coil segment4.

As described above, the projecting portion4dof the eighth-layer coil segment4is bent in the counterclockwise direction D1while being bent in the outward direction D3, and thus, a return force (spring back) tending to return in the inward direction D4is generated by an elastic deformation force. Therefore, the return force facilitates clamping for welding since the projecting portion4dof the eighth-layer coil segment4is close to the projecting portion4dof the seventh-layer coil segment4in comparison with the method without a return force.

When the split claw11holding the projecting portion4dof the seventh-layer coil segment4is moved in the clockwise direction D2, the movement trajectory also includes the movement in the inward direction D4. Therefore, when the projecting portion4dof the seventh-layer coil segment4is bent in the clockwise direction D2, the projecting portion4dof the seventh-layer coil segment4is also bent in the inward direction D4. As a result, a return force tending to return in the outward direction D3is generated by an elastic deformation force. This causes the projecting portion4dof the seventh-layer coil segment4to be close to the projecting portion4dof the eighth-layer coil segment4, which further facilitates clamping for welding.

Further, the first to third extended blades13ato13care such that the edge portion contacting the projecting portion4dis chamfered in an arc shape, which can prevent the projecting portion4dfrom being damaged by the first to third extended blades13ato13c.

The projecting portions of the sixth-layer, fourth-layer, and second-layer coil segments4are bent in the same manner as the projecting portion4dof the eighth-layer coil segment4, and the projecting portions4dof the fifth-layer, third-layer, and first-layer coil segments4are bent in the same manner as the projecting portion4dof the seventh-layer coil segment4. Thus, the projecting portion4dof the sixth-layer coil segment4is close to the projecting portion4dof the fifth-layer coil segment4, the projecting portion4dof the fourth-layer coil segment4is close to the projecting portion4dof the third-layer coil segment4, and the projecting portion4dof the second-layer coil segment4is close to the projecting portion4dof the first-layer coil segment4.

Note that at least one of the projecting portions4dof the even-number-th layer coil segments4may be bent in the outward direction D3while being bent in the counterclockwise direction D1, and the projecting portions4dof the odd number-th layer coil segments4may not be bent in the inward direction D4.

In the stator1, the first unit includes the first-layer to fourth-layer coil segments4and the second unit includes the fifth-layer to eighth-layer coil segments4. In the present embodiment, in order to insulate between the first unit and the second unit, the projecting portion4dof the fourth-layer coil segment4needs to be insulated from the projecting portion4dof the fifth-layer coil segment4.

In the present embodiment, a return force tending to return in the inward direction D4is generated by an elastic deformation force in the projecting portion4dof the fourth-layer coil segment4, which can reliably form a clearance between the projecting portion4dof the fourth-layer coil segment4and the projecting portion4dof the fifth-layer coil segment4and can reliably insulate therebetween. In the present invention, preferably at least the projecting portion4dof the fourth-layer coil segment4is bent in the counterclockwise direction D1while being bent in the outward direction D3.

When there are three or more units having a plurality of coil segments4, the projecting portion4dof the coil segment4disposed at the outermost circumference of each unit other than the unit located at the outermost circumference is preferably bent in the counterclockwise direction D1while being bent in the outward direction D3.

Note that in the above embodiment, the projecting portions4dof the even-number-th layer coil segments4are bent in the outward direction D3while being bent in the counterclockwise direction D1, but a return force tending to return in the inward direction D4may be generated in the projecting portions4dor a stress may be applied in the outward direction D3without bending the projecting portions4din the outward direction D3.

Alternatively, without providing the first to third extended blades13ato13c, a holding member which is not opened in the outward direction D3or the inward direction D4may be used to hold the projecting portions4d, and by moving the holding member in the outward direction D3, the projecting portions4dheld by the holding member may be bent in the outward direction D3.