Patent Application
20080024253
The present invention will be understood more fully from the detailed description given hereinafter and from the accompanying drawings of the preferred embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments but are for the purpose of explanation and understanding only.
In the accompanying drawings:
The preferred embodiments of the present invention will be described hereinafter with reference to
It should be noted that, for the sake of clarity and understanding, identical components having identical functions in different embodiments of the invention have been marked, where possible, with the same reference numerals in each of the figures.
As shown in
The motor 2 includes a cylindrical yoke 5 for forming a magnetic circuit, permanent magnets 6 arranged on the inner periphery of the yoke 5 to create a magnetic field, an armature 7 disposed on the inner periphery of the permanent magnets 6, brushes 8 for supplying electric power from a battery (not shown) to the armature 7, and an end frame 9 that covers the rear open end of the yoke 5.
The electromagnetic switch 3 includes a solenoid 10 and a contacts cover 11 for receiving therein main contacts of the motor circuit. The electromagnetic switch 3 works to selectively connect and disconnect the main contacts; it also works to shift the pinion gear 4 forward via a shift level (not shown) to mesh with the ring gear of the engine.
Referring to
The solenoid 10 includes a cylindrical electromagnetic coil 13, a fixed iron core 14 to be magnetized upon energizing the electromagnetic coil 13, a plunger 15 to move within the electromagnetic coil 13, and a case 17 receiving therein all the other parts of the solenoid 10.
The contacts cover 11 is made of a resin and has the shape of a cylindrical cup with an end wall 11a and a side wall 11b. The contacts cover 11 is fixed to the rear end of the case 17 by crimping, with a packing 16 interposed between the front end of contacts cover 11 and the rear end of the fixed iron core 14.
The electromagnetic switch 3 further includes a pair of fixed contacts 19 and 20, which serve as the main contacts of the motor circuit, and a movable contact 21 working to selectively connect and disconnect the fixed contacts 19 and 20. The fixed contact 19 is electrically connected, as a B fixed contact, to the battery via a terminal bolt 18. On the contrary, the fixed contact 20 is electrically connected, as an M fixed contact, directly to the motor 2 without a terminal bolt intervening therebetween. The movable contact 21 works to selectively connect and disconnect the fixed contacts 19 and 20, thereby selectively closing and opening the motor circuit.
The terminal bolt 18 is insert-molded in the contacts cover 11 so that it extends in the axial direction of the motor 2 through a central portion of the end wall 11a of the circuits cover 11 with a rear end portion 18b thereof protruding from the end wall 11a. To the rear end portion 18b of the terminal bolt 18, a battery cable (not shown) drawn from the battery is connected and fixed by fastening a nut (not shown) onto the rear end portion 18b.
The B fixed contact 19 is sandwiched, within the contacts cover 11, between the a head portion 18a of the terminal bolt 18 and the end wall 11a of the contacts cover 11, so that it is electrically connected to the terminal bolt 18.
The M fixed contact 20 is made up of a conductive metal plate 22 (e.g., a copper plate). More specifically, the metal plate 22 is retained by a rubber grommet 23 that is sandwiched between the rear end of the yoke 5 and the front end of the end frame 9. The metal plate 22 has a first end portion 20 that protrudes from the grommet 23 and is inserted in the contacts cover 11 through the side wall 11b to form the M fixed contact 20. The metal plate 22 also has a second end portion 22b that protrudes from the grommet 23 and is inserted in the motor 2. To the second end portion 22b, there is electrically connected a pigtail 8a of a positive brush 8 that is arranged on the positive side (i.e., the non-ground side) of the armature 7.
The grommet 23 hermetically seals between the metal plate 22 and the yoke 5 and the end frame 9 of the motor 2. The grommet 23 also hermetically seals between the metal plate 22 and the contacts cover 11 of the electromagnetic switch 3. More specifically, referring to
On the other hand, as shown in
Referring back to
The movable contact 21 is, as shown in
After having described the overall structure of the starter 1, the operation thereof will now be described.
When the electromagnetic coil 13 is energized upon turning on a starter switch (not shown), the fixed iron core 14 is magnetized to attract the plunger 15 to move backward against the spring force of a return spring (not shown). With the backward movement of the plunger 15, the shaft 24 fixed to the plunger 15 is also moved backward, thereby bringing the movable contact 21 into contacts with the fixed contacts 19 and 20. After that, the plunger 15 is further moved backward against both the spring forces of the return spring and the contact-pressure spring 26. Thus, the movable contact 21 is pressed against the fixed contacts 19 and 20 by the compressive load of the contact-pressure spring 26, thereby bridging or electrically connecting the fixed contacts 19 and 20. Consequently, the motor circuit is closed so that the motor is supplied with electric power from the battery to start the engine.
As soon as the engine has started, the electromagnetic coil 13 is deenergized upon turning off the starter switch, thus causing the magnetic attraction for the plunger 15 to disappear. Then, the plunger 15 is moved forward by the spring force of the return spring to return to the initial rest position thereof. With the forward movement of the plunger 15, the shaft 24 is also moved backward, thereby detaching the movable contact 21 from the fixed contacts 19 and 20. Consequently, the fixed contacts 19 and 20 are electrically disconnected, and thus the motor circuit is opened. As a result, the electric power supply from the battery to the motor 2 is interrupted.
The above-described starter 1 according to the present embodiment has the following advantages.
In the starter 1, the electromagnetic switch 3 is disposed close to and radially outward of the motor 2. The electromagnetic switch 3 includes the terminal bolt 18, which extends in the axial direction of the motor 2 and has the rear end portion 18b protruding from the rear end wall 11a of the contacts cover 11, and the B fixed contact 19 connected to the terminal bolt 18. The electromagnetic switch 3 also includes the conductive metal plate 22 that has the first end portion 20, which is inserted in the contacts cover 11 through the side wall 11b thereof to make up the M fixed contact 20, and the second end portion 22b inserted in the motor 2 so as to be directly connected to the pigtail 8a of the positive brush 8.
With the above configuration, the contacts cover 11 has only the single terminal bolt 18 for connecting the B fixed contact 19 to the battery, without another one for connecting the M fixed contact 20 to the motor 2 as in the above-mentioned conventional starter.
Further, since the terminal bolt 18 extends through the rear end wall 11a of the contacts cover 11 whereas the metal plate 22 extends through the side wall 11b of the same, a sufficient insulation distance between the terminal bolt 18 and the metal plate 22 can be definitely secured.
Consequently, the diameter of the contacts cover 11 and thus the dimension of the whole electromagnetic switch 3 in the radial direction of the motor 2 can be minimized.
Further, in the starter 1, the terminal bolt 18 is configured to extend through the central portion of the end wall 11a of the contacts cover 11.
With this configuration, a sufficient working space is secured around the terminal bolt 18. Consequently, it is easy to fasten the nut onto the terminal bolt 18 for connecting the battery cable to the terminal bolt 18.
Moreover, in fastening the nut onto the terminal bolt 18, the fastening force can be evenly transmitted from the circumference of the terminal bolt 18 to the contacts cover 11, thus avoiding any local concentration of stress in the contacts cover 11.
Furthermore, with the above configuration, an even surface distance is secured between the circumferences of the terminal bolt 18 and the rear end wall 11a of the contacts cover 11, thereby making it possible to further minimize the diameter of the contacts cover 11.
This embodiment illustrates a starter 1A which has a structure almost identical to that of the starter 1 according to the first embodiment. Accordingly, only the differences between the starters 1 and 1A will be described hereinafter.
As shown in
More specifically, in the starter 1A, the first end portion of the metal plate 22 is inserted in the contacts cover 11 to form the M fixed contact 20. The second end portion 22b of the metal plate 22 is bent to extend in the axial direction of the motor 2, and thus is not inserted in the motor 2. In addition, a sealing member 29 is employed, instead of the grommet 23, to hermetically seal between the metal plate 22 and the contacts cover 11.
The connecting plate 28 is made of a conducive metal, such as copper, and is retained by the grommet 23. The connecting plate 28 has a first end portion 28a, which protrudes from the grommet 23 into the motor 2 and is directly connected to the pigtail 8a of the positive brush 8, and a second end portion 28b that protrudes from the grommet 23 out the motor 2 and is directly connected to the second end portion 22b of the metal plate 22.
When the axial distance from the mount face A of the motor 2 to the metal plate 22 inserted in the contacts cover 11 is different from the axial distance from the mount face A to the grommet 23 inserted in the motor 2, it is difficult to directly connect the metal plate 22 to the pigtail 8a of the positive brush 8 through the grommet 23.
In such cases, however, it is still possible to reliably connect the metal plate 22 to the pigtail 8a of the positive brush 8 through the connecting plate 28 as described above.
In addition, the metal plate 22 and the connecting plate 28 may be connected to each other by, for example, welding, soldering, or crimping.
The above-described starter 1A according to present embodiment has the same advantages as the starter 1 according to the first embodiment.
This embodiment illustrates a starter 1B which has a structure almost identical to that of the starter 1 according to the first embodiment. Accordingly, only the differences between the starters 1 and 1B will be described hereinafter.
As shown in
Each of the field coils 60 has a first end 60a and a second end 60b. All the first ends 60a of the field coils 60 are connected to a connection bar 30 provided in the motor 2; all the second ends 60b of the field coils 60 are connected to the pigtail 8a of the positive brush 8.
Further, in the present embodiment, the second end portion 22b of the metal plate 22 is inserted in the motor 2 so as to be directly connected to the connection bar 30.
With the above configuration, the field coils 60 are electrically connected in series with the armature 7 of the motor 2.
The above-described starter 1B according to present embodiment has the same advantages as the starter 1 according to the first embodiment.
While the above particular embodiments of the invention have been shown and described, it will be understood by those who practice the invention and those skilled in the art that various modifications, changes, and improvements may be made to the invention without departing from the spirit of the disclosed concept.
For example, it is possible to provide a starter IC which has a structure that is a combination of the structures of the starters 1B and 1C according to the second and third embodiments of the invention.
More specifically, though not graphically shown, the starter 1C may include a plurality of field coils 60 for creating the magnetic field. The first ends 60a of the field coils 60 may be connected to a connection bar 30 provided in the motor 2; the second ends 60 of the same may be connected to the pigtail 8a of the positive brush 8. Further, the second end portion 22b of the metal plate 22 may be located outside the motor 2. The starter 1C may further include a conductive connecting member 28. The first end portion 28a of the connecting member 28 may be inserted in the motor 2 so as to be directly connected to the connection bar 30; the second end portion 28b of the same may be located outside the motor 2 and connected to the second end portion 22b of the metal plate 22. The starter 1C having such a structure will have the same advantages as the starters 1-1B according to the previous embodiments.
Such modifications, changes, and improvements within the skill of the art are intended to be covered by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-203057 | Jul 2006 | JP | national |
