JP4075750B2 - Starter - Google Patents

Description

  The present invention relates to a starter for starting an internal combustion engine, and more particularly to preventing overheating of the starter.

Generally, when starting an automobile engine, the starter operation is manually controlled by the user's key switch operation.For example, if an abnormality such as a return failure of the key switch occurs, the starter motor is switched from the power source to the starter motor via the electromagnetic switch. Since a large current of several hundred amperes is continuously supplied for a long time, an excessive thermal load may be applied to the starter.
In addition, when a problem occurs in the electromagnetic switch for some reason, the starter motor may be continuously energized with no load.

In this way, it is conceivable that the starter motor is electrically disconnected from the power source by some means at the time of an abnormality in which an excessive thermal load is generated. For example, the starter described in Patent Document 1 shows a structure in which a thermal fuse is provided in a motor circuit, and the motor circuit is cut off when the temperature fuse reaches a predetermined temperature.
Also, in the starters described in Patent Documents 2 and 3, a recess having a locally reduced cross-sectional area is provided in a motor lead wire, a brush lead wire (pigtail), etc., and this recess reaches a predetermined temperature due to heat generated by an energizing current. Then, a structure that melts and shuts off the motor circuit is shown.
International Publication No. WO00 / 19091 Pamphlet Japanese Patent Laid-Open No. 10-66311 French Patent Application Publication No. 2785086

  In the known technology disclosed in Patent Document 1 above, since the thermal fuse is installed outside the starter, interference between components around the starter (for example, engine accessories and electrical wiring) and the thermal fuse is prevented. It may be necessary to deteriorate the mountability on the vehicle. In addition, the number of parts increases due to the addition of the thermal fuse, which causes an increase in cost.

  In the known techniques disclosed in Patent Documents 2 and 3, since a recess is originally provided in a motor lead wire or brush lead wire having high thermal conductivity, high heat generated in the recess easily conducts through the lead wire itself and escapes easily. It has become. For this reason, in order to surely blow off at the recess, the cross-sectional area of the recess needs to be considerably reduced, and there is a risk of disconnection due to vibration or the like during traveling of the vehicle, which is problematic in terms of reliability. Above all, locally reducing the cross-sectional area of the lead wire or the like used in the motor circuit has a big problem that the starter output decreases because the circuit resistance increases.

  The present invention has been made based on the above circumstances, and its purpose is to use an additional thermal load or the like when an excessive thermal load is applied to the current path of the starter than during normal use. An object of the present invention is to provide a starter that has a highly reliable power cut-off function capable of reliably cutting off a current path and that can suppress a decrease in output due to the provision of the power cut-off function.

(Invention of Claim 1)
In the starter of the present invention, when an excessive thermal load is applied to the current path through which the starting current flows during normal use, the field coil is blown out of a plurality of parts constituting the current path, thereby causing the current path to has a cut-off current can be supplied shielding function, the current blocking function is, over a half or more of a range of the total length of the field coil, is provided by reducing the cross-sectional area of the field coil.

In the present invention, by reducing the cross-sectional area of the field coil , it is possible to provide a portion having a high current density in the current path. As a result, when an excessive thermal load is applied to the current path of the starter than during normal use, the field coil has a high current density due to Joule heat generated in the entire area where the sectional area of the field coil is reduced. The starter current path can be interrupted by fusing at the site. According to this configuration, unlike the known technique (Patent Document 1) described in the background art, it is not necessary to add a component such as a thermal fuse or a bimetal, so that an increase in cost associated with an increase in the number of components can be suppressed.

Further, the energization cut-off function of the present invention does not locally reduce the cross-sectional area of the lead wire as in the known techniques (Patent Documents 2 and 3) described in the background art, but 1 of the total length of the field coil. / 2 or more by reducing the cross-sectional area over a wide range. In this case, compared with the known technology, the area where the cross-sectional area is reduced is wide, so the temperature drop due to heat conduction is suppressed, and the entire area where the cross-sectional area is reduced is used for fusing. Can do. That is, it is difficult for the heat generated at the portion where the cross-sectional area is reduced to escape. As a result, even if the cross-sectional area of the lead wire is not locally reduced as in the prior art, the heat generated in the entire area where the cross-sectional area is reduced can be used for efficient and short fusing. Is possible.

Furthermore, in the energization cut-off function of the present invention, the heat generation of the entire part with the reduced cross-sectional area can be used when the cross-sectional area is reduced over a wider range than when the cross-sectional area is locally reduced. Therefore, an equivalent energization cut-off time can be set even with a relatively large cross-sectional area. That is, the change in the cross-sectional area can be reduced between the part where the cross-sectional area is not reduced and the part where the cross-sectional area is reduced, and the stress concentration in the part where the cross-sectional area changes can be suppressed. As a result, it is possible to suppress a decrease in the mechanical strength of the field coil due to the reduction in the cross-sectional area, so that there is a low possibility of disconnection with respect to vibrations during vehicle running and the like, and it is possible to provide a highly reliable energization cutoff function. .

Further, by providing a portion having a reduced cross-sectional area over a wide range of 1/2 or more of the total length with respect to the field coil , it is excessive even if the cross-sectional area is not extremely reduced as in the known technique. When a thermal load occurs, it can be surely melted at a portion having a high current density, so that an increase in circuit resistance due to a reduction in cross-sectional area can be reduced, and a decrease in output of the starter associated therewith can be suppressed.

(Invention of Claim 2)
In the starter according to claim 1, the field coil having a current-carrying-off function is disposed inside the motor.
In this case, when the portion where the cross-sectional area is reduced generates heat and the field coil is melted, the melted field coil causes a thermal effect on the vehicle-side components and wire harnesses arranged outside the motor. Therefore, when an excessive thermal load is generated in the current path of the starter, the current path can be safely interrupted.

(Invention of Claim 3 )
In the starter according to claim 1 or 2 , the energization cutoff function is provided by reducing the cross-sectional area of the field coil over the entire length.
In this case, since the site | part which reduces a cross-sectional area can be set longer, the thermal energy required for fusing can be obtained efficiently. In addition, when forming a portion having a large cross-sectional area and a portion having a small cross-sectional area in the field coil, it is difficult to manufacture, whereas when reducing the cross-sectional area of the field coil over the entire length, Since a thin field coil may be used, it is advantageous in terms of cost.

(Invention of Claim 4 )
The starter according to any one of claims 1 to 3 , further comprising a high-temperature repellent component arranged in contact with or close to a combustible member, other than the field coil , among the plurality of components constituting the current path. The cross-sectional area of the high-temperature repellent component is increased over the entire length so that the current density of the high-temperature repellent component is the smallest among the plurality of components.
According to this configuration, since the current density of the high-temperature repellent component is the smallest, that is, the cross-sectional area is large, Joule heat generated by the current flowing through the high-temperature repellent component can be suppressed. As a result, when an excessive thermal load is applied to the current path of the starter, it is possible to suppress the thermal influence on the combustible member before the field coil having the energization cutoff function is melted.

(Invention of Claim 5 )
In the starter according to claim 4 , the current density of the high-temperature repellent component is approximately ½ of the current density of the portion where the cross-sectional area of the field coil is reduced.
As a result, when an excessive thermal load is applied to the current path of the starter, the temperature of the high-temperature repellent component can be reduced to approximately half of the temperature at which the field coil is melted. As a result, it is possible to suppress the thermal influence on the combustible member that is in contact with or close to the high temperature repellent component.

(Invention of Claim 6 )
The starter according to claim 4 or 5, hot repellent component is held by the rubber grommet which is flammable member, one end of which is connected to the motor terminal is taken out outside the frame of the motor, the other end A motor lead wire whose side is drawn inside the frame.
Accordingly, when an excessive thermal load is applied to the current path of the starter, the thermal load received by the rubber grommet from the motor lead wire can be suppressed, and thermal damage to the grommet can be prevented.

(Invention of Claim 7 )
The starter according to claim 4 or 5, hot repellent component is held by the rubber grommet which is flammable member, one end of which is connected to the motor terminal is taken out outside the frame of the motor, the other end It is a connection bar that is held by a resin lead, which is a flammable member, and a motor lead wire that is pulled into the inside of the frame and electrically connects the motor lead wire and the field coil.
Accordingly, when an excessive thermal load is applied to the current path of the starter, the thermal load received by the rubber grommet from the motor lead wire can be suppressed, and thermal damage to the grommet can be prevented. Similarly, the thermal load that the resin insulator receives from the connection bar can be suppressed, and thermal damage to the insulator can be prevented.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is a half sectional view of the starter 1.
As shown in FIG. 1, the starter 1 of this embodiment includes a motor 2 that generates a rotational force, an output shaft 3 that is driven by the motor 2 to rotate, and a pinion moving body that is disposed on the output shaft 3. (Described later) and a contact means A provided in the motor circuit (described later) shown in FIG. 4 as well as functioning to push the pinion moving body counterclockwise (leftward in FIG. 1) via the shift lever 4 It is comprised from the electromagnetic switch 5 etc. which open / close.

The motor 2 is a well-known DC motor including a field magnet 6 (see FIG. 2) that generates magnetic flux, an armature 8 having a commutator 7, a brush 9 disposed on the commutator 7, and the like.
As shown in FIG. 2, the field magnet 6 forms a magnetic circuit and also has a cylindrical yoke 6a that also serves as a machine frame of the motor 2, a plurality of field poles 6b fixed to the inner periphery of the yoke 6a, and The field coil 6c is composed of a plurality of field coils 6c wound around each field magnetic pole 6b, and the field coil 6c is provided with a current-carrying means (described later) of the present invention. The starter 1 of this embodiment uses a four-pole motor 2 as shown in FIG. 4, and four field poles 6b and four field coils 6c are provided.

The armature 8 includes a rotating shaft 8a, an armature core 8b fixed to the rotating shaft 8a, and an armature coil 8c wound around the armature core 8b. The inner end of the output shaft 3 is inserted into the cylindrical portion provided on the motor side end (the right end in FIG. 1) and supported by the output shaft 3 so as to be relatively rotatable. However, the end frame 10 covering the rear part of the motor 2 is rotatably supported.
The commutator 7 is configured by arranging a plurality of segments insulated and held on the outer periphery of the rear end of the rotating shaft 8a in a cylindrical shape, and each segment is electrically and mechanically coupled to the armature coil 8c. .

As shown in FIG. 4, the brush 9 includes two plus-side brushes 9 a connected to the field coil 6 c via the brush pigtail 11 and two minus-side brushes connected to the ground via the brush pigtail 12. 9b, each accommodated in a brush holder 13 (see FIG. 1), disposed on the outer periphery of the commutator 7, and pressed against the outer peripheral surface of the commutator 7 by a brush spring (not shown).
The output shaft 3 is arranged coaxially with the rotating shaft 8a of the armature 8 via a speed reducer, one end on the side opposite to the motor is rotatably supported by the front housing 14, and the other end is The center case 15 is rotatably supported.

The speed reduction device is configured by a known planetary gear mechanism, and converts the rotational speed of the armature 8 into the revolving motion of the planetary gear 16 to reduce the speed. The revolving motion of the reduced planetary gear 16 is transmitted to the output shaft 3 via the gear shaft 17 that supports the planetary gear 16.
The center case 15 is disposed between the front housing 14 and the yoke 6a so as to cover the outer periphery of the reduction gear. In addition, a sliding plate type shock absorber 18 is incorporated between the center case 15 and the speed reducer to absorb the excessive torque when the torque is applied to the speed reducer.

The pinion moving body includes a one-way clutch described below and a pinion gear 19 for transmitting the rotational force of the motor 2 to an engine ring gear (not shown).
The one-way clutch transmits the rotation of the output shaft 3 to the pinion gear 19. The spline tube 20 that is helically splined to the output shaft 3, the outer 21 provided integrally with the spline tube 20, It is comprised from the inner 22 arrange | positioned inside, the roller 23 etc. which are arrange | positioned in the wedge-shaped space formed between the outer 21 and the inner 22. As shown in FIG.
The pinion gear 19 is provided integrally with the inner 22 of the one-way clutch, is disposed on the inner side of the inner 22 opposite to the motor in the axial direction (left side in FIG. 1), and is supported by the output shaft 3 via a bearing 24.

As shown in FIG. 3, the electromagnetic switch 5 includes an exciting coil 26 that generates a magnetic force when energized from a battery 25 (see FIG. 4) by closing a start switch (not shown), and an inner side of the exciting coil 26. 3 and the plunger 27 that is attracted to the right in FIG. 3 by receiving the magnetic force generated in the exciting coil 26, and the return for pushing back the plunger 27 when the energization to the exciting coil 26 is stopped and the magnetic force disappears. It is composed of a spring 28 and the like.
The shift lever 4 connects the plunger 27 of the electromagnetic switch 5 and the spline tube 20 of the one-way clutch, is provided so as to be able to swing around the fulcrum part 4a, and transmits the movement of the plunger 27 to the pinion moving body.

  As shown in FIG. 3, the contact means A includes a set of fixed contacts 31 (31 a and 31 b) connected to a motor circuit (see FIG. 4) via two external terminals 29 and 30, and a plunger 27. The movable contact 32 is configured to move in conjunction with the movement (or integrally with the plunger 27). The movable contact 32 abuts against a set of fixed contacts 31, and the fixed contacts 31 are electrically connected to each other to close. When the movable contact 32 is separated from the set of fixed contacts 31, the state is opened.

The two external terminals 29 and 30 are a battery terminal 29 electrically and mechanically coupled to one fixed contact 31a, and a motor terminal 30 electrically and mechanically coupled to the other fixed contact 31b. Both are fixed to the contact cover 5 a of the electromagnetic switch 5.
A battery cable 33 (see FIG. 4) is connected to the battery terminal 29 at a bolt portion taken out of the contact cover 5a, and a motor terminal 30 is connected to a motor at the bolt portion taken out of the contact cover 5a. A lead wire 34 is connected.

  The motor lead wire 34 is held by a rubber grommet 35 attached to the end frame 10, and one end side is taken out of the end frame 10, and a ring-shaped terminal portion 34 a (see FIG. 2) is fitted to the motor terminal 30 and is fastened and fixed by a nut 36 (see FIG. 1). The other end side of the motor lead wire 34 is inserted into the end frame 10 through the grommet 35, and the end thereof is connected to a copper connection bar 37 (see FIG. 4).

  The connection bar 37 is a component that constitutes a part of the motor circuit shown in FIG. 4, and the anti-brush side ends of the four field coils 6c are connected to each other, and the motor lead wire 34 and each field coil 6c are connected. Electrically connected. As shown in FIG. 2, the connection bar 37 is insulated and held by a resin insulator 38 incorporated inside the opening on the end frame 10 side of the yoke 6a.

  The motor circuit forms a current path through which the starting current flows in the starter, and includes a plurality of components shown in FIG. 4, that is, a battery terminal 29, contact means A (fixed contact 31 and movable contact 32), motor terminal 30, Motor lead wire 34, connection bar 37, field coil 6c, plus-side brush pigtail 11, plus-side brush 9, armature 8 (armature coil 8c and commutator 7), minus-side brush 9, and minus-side brush When the contact means A is constituted by the pigtail 12 and the contact means A is closed, a starting current flows through the plurality of parts in order as shown by solid line arrows in FIGS. In addition, the numbers with circles shown in the figure indicate the order in which the starting current flows.

Next, the energization cutoff function of the present invention will be described.
The energization cutoff function is a function that shuts off the motor circuit by blowing out certain parts among the multiple parts that make up the motor circuit when an excessive thermal load is applied to the motor circuit than during normal use. It is provided by reducing the cross-sectional area of the specific part over a range of 1/2 or more of the total length of the specific part. In the first embodiment, the specific component is the field coil 6c, and the cross-sectional area of the copper wire used for the field coil 6c is reduced over the entire length. That is, a copper wire having a smaller diameter than that of the conventional field coil 6c is used. Specifically, a copper wire having a cross-sectional area of about 90% of a conventional product is used.

  In general, the cross-sectional area of each component is set so that the current density of each of the components constituting the motor circuit is substantially the same. For example, when the cross-sectional area of the motor lead 34 connected in series to the motor terminal 30 is used as a reference, the cross-sectional area of each component is set according to the number of parallel circuits with respect to the motor lead 34 as shown in FIG. . Accordingly, since the number of parallel circuits of the field coil 6c used in the four-pole motor 2 is “4”, the sectional area of the field coil 6c is approximately ¼ of the sectional area of the motor lead wire 34. Become. On the other hand, when the field coil 6c having a cross-sectional area of approximately ¼ of the cross-sectional area of the motor lead wire 34 is used as a conventional product, the field coil 6c having a current-canceling function of the present invention is the conventional product. Further, the cross-sectional area is reduced by about 10%, so that the current density is larger than that of other components.

Next, the operation of the starter 1 will be described.
When the excitation coil 26 of the electromagnetic switch 5 is energized and the plunger 27 is attracted by closing the start switch, the pinion moving body is pushed out on the output shaft 3 in the anti-motor direction via the shift lever 4, and the pinion gear 19. Stops in contact with the ring gear of the engine.
On the other hand, when the contact means A is closed by the movement of the plunger 27, the armature 8 is energized and rotated, and the rotation of the armature 8 is decelerated by the reduction device and transmitted to the output shaft 3.

When the output shaft 3 rotates, the rotation of the output shaft 3 is transmitted to the pinion gear 19 via the one-way clutch. Is transmitted to crank the engine.
When the start switch is opened after the engine is started, the energization to the exciting coil 26 is stopped and the magnetic force disappears, so that the plunger 27 is pushed back by the reaction force of the return spring 28. By this movement of the plunger 27, the contact means A is opened and the energization to the motor 2 is stopped, and the pinion moving body moves backward on the output shaft 3 in the counter ring gear direction via the shift lever 4, so that FIG. Stop at the indicated rest position.

  In the above operation, for example, when a return failure of the start switch occurs, or when the motor 2 is continuously energized with no load for some reason, insulation breakdown occurs in the armature coil 8c and the coils are short-circuited. Then, since a large current of several hundred amperes is continuously supplied from the battery 25 to the motor 2, an excessive thermal load is applied to the motor circuit as compared with the normal use. On the other hand, in the field coil 6c having a reduced cross-sectional area compared to the conventional product, the current density is larger than that of the other parts because the cross-sectional area is reduced, so the Joule heat generated by the flow of a large current also increases. .

As a result of the above, the entire field coil 6c generates heat and melts at a particularly high current density portion, so that the motor circuit is cut off and continuous energization to the motor 2 is avoided.
Since the field coil 6c is usually wound a plurality of times (for example, four times) around one field magnetic pole 6b, the coating of the field coil 6c is damaged by heat generation, and adjacent coils are short-circuited. When (rare), the current density of the portion decreases, so that the portion wound around the field pole 6b is hardly melted. Actually, as shown by the broken line portion in FIG. 6, the field pole 6b There is a high possibility of fusing at the end portion 6d (winding start portion or winding end portion) of the field coil drawn out from.

(Effect of Example 1)
In the starter 1 of the present embodiment, the field coil 6c is provided with a function of interrupting energization by reducing the cross-sectional area of the field coil 6c over the entire length. According to this configuration, for example, compared with the known techniques (Patent Documents 2 and 3) in which the cross-sectional area of the motor lead wire 34 is locally reduced to have a fuse function, the portion where the cross-sectional area is reduced is wide. Therefore, the temperature drop due to heat conduction is suppressed. That is, since the Joule heat generated in the field coil 6c is difficult to escape, the heat generation of the entire field coil 6c can be used for efficient and short fusing.
According to this configuration, the field coil 6c, which is a part of the motor circuit, is provided with a current cut-off function. Therefore, it is necessary to add a component such as a thermal fuse or a bimetal as in the known technique (Patent Document 1). Therefore, it is possible to suppress an increase in cost associated with an increase in the number of parts.

  Further, since the heat generation of the entire field coil 6c can be efficiently utilized for fusing, there is no need to extremely reduce the cross-sectional area of the field coil 6c, and as described above, at most 10% of the conventional product. Only by reducing the cross-sectional area to the extent, it is possible to sufficiently perform the current-cutoff function. As a result, the increase in circuit resistance due to the reduction in the cross-sectional area can be reduced as much as possible, so that a decrease in the output of the starter 1 due to the increase in circuit resistance can be suppressed.

  Further, as in the known technique (Patent Documents 2 and 3), when the cross-sectional area of the lead wire is locally reduced, stress concentration occurs at that portion, so that the mechanical strength of the lead wire is reduced. Since the field coil 6c has a reduced cross-sectional area over its entire length, stress concentration can be eliminated. As a result, the mechanical strength of the field coil 6c due to the reduction in the cross-sectional area is not greatly reduced, and the possibility of disconnection due to vibration during traveling of the vehicle is reduced, providing a highly reliable power-off function. it can.

  Further, in the configuration disclosed in the known techniques (Patent Documents 2 and 3), processing for locally reducing the cross-sectional area of the lead wire is required. In this embodiment, the cross-sectional area of the field coil 6c is required. Is reduced over the entire length. That is, only the field coil 6c having a smaller wire diameter than the conventional product is used, and no special processing is required for the field coil 6c, which is advantageous in terms of cost.

  In the present embodiment, by providing the field coil 6c with an energization cutoff function, for example, a distance from the grommet 35 (made of rubber) formed of a combustible member can be secured. As a result, the influence of the high heat of the field coil 6c on the grommet 35 before the field coil 6c is melted can be reduced, and thermal damage to the grommet 35 can be prevented. Further, since the field coil 6c having an energization cutoff function is disposed inside the motor 2, when the field coil 6c is melted, vehicle-side components, wire harnesses, and the like disposed outside the motor 2 are used. The motor circuit can be safely shut off with little thermal influence on the motor.

  In the first embodiment, the example in which the cross-sectional area of the field coil 6c is reduced over the entire length has been described. However, the cross-sectional area is reduced over at least a range of 1/2, in other words, a range of 1/2 or more. Therefore, it may have an energization cutoff function. In this case, since the range in which the cross-sectional area is reduced is shortened, it is desirable to increase the cross-sectional area reduction rate accordingly, that is, to make the wire diameter thinner. For example, when the cross-sectional area of the field coil 6c is reduced over a range of ½ of the total length, the cross-sectional area may be reduced by about 30% from the conventional product described in the first embodiment.

  Moreover, the site | part which reduces a cross-sectional area does not necessarily need to be continuous, For example, it is also possible to provide separately in the winding start side and winding end side of the field coil 6c. Of the field coil 6c, the portion of the field coil 6b that is wound around the field pole 6b escapes heat to the field pole 6b or the yoke 6a even if it generates heat. The winding start portion and the winding end portion that extend along the axial direction are likely to become high temperature, and fusing is likely to occur. Therefore, since the portion that is wired without being continuously held in contact with the yoke 6a or the like among these winding start portion and winding end portion is likely to become hot, such a portion is assumed as a fusing occurrence location. It is desirable to design.

  Further, by applying a tensile force in advance to the winding start side and the winding end side of the field coil 6c, when the field coil 6c is melted at the winding start portion or the winding end portion, an elastic body or the like is used. Without using special parts, the melted portion is pulled away by a previously applied tensile force, so that the motor circuit can be shut off quickly and reliably.

In the present embodiment, the field coil 6c is provided with a current interruption function, and the motor lead wire 34 held by the flammable grommet 35 and the connection bar 37 held by the resin insulator 38 also having flammability are provided. This is an example in which the cross-sectional area is larger than that of the conventional product.
The starter 1 uses combustible members such as a rubber grommet 35 that holds the motor lead wire 34 and a resin insulator 38 that holds the connection bar 37. For this reason, when an excessive thermal load is applied to the motor circuit, the grommet 35 and the insulator 38 may be affected by high heat.

  Therefore, the current density is reduced by increasing the cross-sectional area of the motor lead wire 34 held by the grommet 35 and the connection bar 37 held by the insulator 38 as compared with the conventional product. Specifically, as shown in FIG. 7, the cross-sectional area of the motor lead 34 is about 1.5 times that of the conventional product, the current density is reduced to 1 / 1.5, and the cross-sectional area of the connection bar 37 is reduced to the conventional product. Current density is reduced to ½. The other components constituting the motor circuit (field coil 6c, plus-side brush pigtail 11, minus-side brush pigtail 12, armature coil 8c) are the same as those in the first embodiment.

According to the configuration of the present embodiment, when an excessive thermal load is applied to the motor circuit, similarly to the first embodiment, the motor circuit is blown at the winding start portion or winding end portion of the field coil 6c. Since the heat generation of the motor lead wire 34 and the connection bar 37 that can be cut off and has a lower current density than the conventional product can be suppressed, the grommet 35 and the insulator 38 can be protected from high heat .

[Reference Example 1]
FIG. 8 is a plan view of the motor lead 34.
This reference example, the current blocking function is intended showing an example in which the motor leads 3 4 illustrates an example of the cross-sectional area of the motor lead 34 is reduced over the entire length in FIG. 8 (b), FIG. FIG. 8 (c) shows an example in which the cross-sectional area of the motor lead wire 34 is reduced over ½ of the total length.

When reducing the cross-sectional area of the motor lead 34 over the entire length, that is, when using the motor lead 34 having a smaller wire diameter than the conventional product shown in FIG. 8A, for example, about 60% of the conventional product. The cross-sectional area of This is because the total length of the motor lead wire 34 is shorter than that of the field coil 6c, and in order to obtain the thermal energy necessary for fusing, it is better to increase the reduction ratio of the cross-sectional area as the total length becomes shorter. Because.
When the cross-sectional area of the motor lead 34 is reduced over ½ or more of the total length, that is, when a portion having the same cross-sectional area as that of the conventional product shown in FIG. The cross-sectional area of the part is about 40% of the conventional product .

[Reference Example 2]
FIG. 9 is a perspective view of the brush 9.
This reference example, the current blocking function is intended showing an example in which the brush pigtail 1 1 shows an example in which the cross-sectional area of the brush pigtail 11 is reduced over the entire length in FIG. 9 (b), 9 ( The example which reduced the cross-sectional area of the brush pigtail 11 over 1/2 or more of full length is shown to c).

When reducing the cross-sectional area of the brush pigtail 11 over its entire length, that is, when using the brush pigtail 11 having a thinner wire diameter than the conventional product shown in FIG. The area. This is the same reason as in the case of the motor lead 34 described in Reference Example 1 .
When the cross-sectional area of the brush pigtail 11 is reduced over ½ or more of the total length, that is, when the part having the same cross-sectional area as that of the conventional product shown in FIG. The cross-sectional area is about 40% of the conventional product .

[Reference Example 3]
This reference example is intended showing an example in which a current blocking function to the connection bars 3 7, when decreasing over the cross-sectional area of the connection bars 37 to the full-length, i.e., a thin connection bar 37 in diameter than conventional When used, for example, the cross-sectional area is about 70% of the conventional product. This is because the total length of the connection bar 37 is shorter than that of the field coil 6 c and longer than the motor lead wire 34 and the brush pigtail 11, so that the reduction rate of the cross-sectional area is set smaller than that of the motor lead wire 34 and the brush pigtail 11. is doing.
In addition, when the cross-sectional area of the connection bar 37 is reduced over ½ of the total length, that is, when a portion having the same cross-sectional area as that of the conventional product is left, the cross-sectional area of the portion having a small diameter is changed to the conventional product. About 50%.

1 is a half sectional view of a starter according to Embodiment 1. FIG. It is sectional drawing (a) and an axial front view (b) of the field concerning Example 1. FIG. 1 is a cross-sectional view of an electromagnetic switch according to Embodiment 1. FIG. 1 is a motor circuit diagram according to Embodiment 1. FIG. 2 is a drawing comparing cross-sectional areas and current densities of components constituting the motor circuit according to the first embodiment. It is a motor circuit diagram which shows the fusing part of the field coil concerning Example 1. FIG. 6 is a diagram comparing cross-sectional areas, current densities, and heat generation amounts of components constituting a motor circuit according to a second embodiment. 6 is a plan view of a motor lead wire according to Reference Example 1. FIG. 10 is a perspective view of a brush according to Reference Example 2. FIG.

Explanation of symbols

1 starter 2 motor 5 the electromagnetic switch 6 field 6a yoke 6b field pole 6c end of the field coil 6d field coil (winding start portion or winding end portion)
7 Commutator 8 Armature 9 Brush 10 End frame (frame)
11 Brush Pigtail 25 Battery 29 Battery Terminal 30 Motor Terminal 34 Motor Lead Wire (High Temperature Repellent Parts)
35 Grommet (flammable material)
37 Connection bar (high temperature repellent parts)
38 Insulator (flammable material)

Claims (7)

In addition to a field and an armature, the field includes a yoke that forms a magnetic circuit, a field pole fixed to the inner periphery of the yoke, and a field coil wound around the field pole. A brush is disposed on a commutator provided in the armature, and a starting current is supplied to the armature from a battery via the brush, thereby generating a rotational force in the armature;
A starter having a battery terminal connected to the battery and a motor terminal connected to the motor, and comprising an electromagnetic switch that electrically connects and disconnects between the battery terminal and the motor terminal,
When an excessive thermal load is applied to the current path through which the starting current flows in the starter than during normal use, among the parts constituting the current path, the field coil is blown to blow the current. It has a power cut off function that can cut off the path,
The current blocking function is over 1/2 or more ranges of the total length of the field coil is provided by decreasing the cross-sectional area of the field coil and, the field coil is previously A starter to which a tensile force is applied . The starter according to claim 1,
The starter according to claim 1, wherein the field coil having the energization cutoff function is disposed inside the motor. The starter according to claim 1 or 2,
The starter characterized in that the energization cutoff function is provided by reducing the cross-sectional area of the field coil over its entire length . The starter according to any one of claims 1 to 3 ,
Among the plurality of parts constituting the current path, in addition to the field coil, a high temperature repellent part disposed in contact with or close to the combustible member is provided, and the current density of the high temperature repellent part is the plurality of the plurality of parts. The starter characterized in that the cross-sectional area of the high-temperature repellent component is increased so as to be the smallest among the components . The starter according to claim 4 ,
The starter characterized in that the current density of the high-temperature repellent component is approximately ½ of the current density of the portion where the cross-sectional area of the field coil is reduced . In starter according to claim 4 or 5,
The high temperature repellent component is held by a rubber grommet which is a combustible member, one end side is taken out from the frame of the motor and connected to the motor terminal, and the other end side is drawn into the frame. Starter characterized by being a motor lead wire . The starter according to claim 4 or 5 ,
The high temperature repellent component is held by a rubber grommet which is a combustible member, one end side is taken out from the frame of the motor and connected to the motor terminal, and the other end side is drawn into the frame. A starter that is a connection bar that is held by a resin insulator, which is a combustible member, and electrically connects the motor lead wire and the field coil .

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