Title of the Invention

ELECTROMAGNET DEVICE FOR STARTER

Background of the Invention

1. FIELD OF THE INVENTION

The present invention relates to an electromagnet device for a starter which starts up an engine mounted in, for example, vehicles.

2. DESCRIPTION OF THE RELATED ART

Hitherto, particularly a lot of starters for starting engines have been used in vehicles. However, in recent years, the number of vehicles equipped with an idling stop function as a method of improving vehicle fuel consumption has increased. In the case of adopting a configuration in which a starter is used for restarting after an idling stop as in normal engine starting, the number of the use of the starter is increased; and therefore, improvement in durability of the starter is required.

On the other hand, an engine room of a vehicle is arranged with numerous constituent components such as devices necessary for driving an engine and transmissions necessary for transmitting power obtained from the engine to tires, in addition to its engine body and starter; and therefore, other constituent components are densely provided in a surrounding area where the starter is located. Recently, in order to improve engine performance, the number of constituent components has increased and the constituent components have increased in size; and therefore, the importance of downsizing of the starter is increased. In order to further improve merchantability, the importance for silence performance is also increased.

As a conventional starter, for example, a mechanism disclosed in Japanese Patent Application No. 2009-246506 is known. The mechanism includes an electromagnetic force unit which makes a pinion engage with a ring gear and an electromagnetic relay coaxially provided in series with the electromagnetic force unit.

Since the starter disclosed in the above described conventional patent document 1 includes a technique which prevents engaging defects by enabling an electromagnet device serving as the electromagnetic force unit and the electromagnetic relay to operate individually, there is a beneficial effect for mounting to a vehicle equipped with an idling stop function.

Further, the electromagnet device serving as the electromagnetic force unit and the electromagnetic relay are coaxially provided in series; and therefore, there is also a beneficial effect for downsizing the starter as a whole.

However, in the starter disclosed in the patent document 1, there arises a problem in that, when the electromagnet device serving as the electromagnetic force unit and the electromagnetic relay are operated at the same time, collision sound of a movable core and a fixed core of the electromagnet device, the collision sound being under screen of sound generated from a motor and an engine or a power transmission portion thereof, is recognized as foreign sound when the only electromagnet device is operated.

SUMMARY OF THE INVENTION

The present invention has been made to solve the foregoing problem, and an object of the present invention is to provide an electromagnet device for a starter capable of reducing collision sound of a movable core and a fixed core by arranging a shock absorbing member between the movable core and the fixed core.

According to the present invention, there is provided an electromagnet device for a starter including: a yoke which forms an outer circumferential portion; an excitation coil which is arranged on an inner circumferential side of the yoke; a movable core which is arranged on an inner circumferential side of the excitation coil; and a fixed core which is fitted to the yoke and is arranged in face-to-face relation with the movable core. In the electromagnet device for the starter, a convex shaped portion is formed on either one side of facing surfaces of the movable core and the fixed core, and a concave shaped portion is formed on the other side thereof, the concave shaped portion being a substantially similar shape to the convex shaped portion and having a through hole in the center thereof, and the concave shaped portion being attached with a shock absorbing member. The shock absorbing member is composed of a shock absorbing portion located on the concave shaped portion and a retained portion passed through the through hole and provided on an opposite side to the shock absorbing portion.

In an electromagnet device for a starter according to the present invention, a shock absorbing member that is larger in repulsive force than in magnetic attractive force of a movable core and a fixed core is arranged between the movable core and the fixed core, whereby it is possible to obtain the electromagnet device for the starter capable of reducing collision sound of the movable core and the fixed core.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a sectional view showing an electromagnet device for a starter according to Embodiment 1 of the present invention;

Fig. 2 is a sectional view showing a shock absorbing member in the electromagnet device for the starter according to Embodiment 1 of the present invention;

Fig. 3 is a front view in which the shock absorbing member in the electromagnet device for the starter according to Embodiment 1 of the present invention is seen from the left direction of Fig.2; and

Fig. 4 is a characteristic view showing distance and magnetic attractive force between facing surfaces of a movable core and a fixed core and repulsive force of the shock absorbing member of the electromagnet device for the starter according to Embodiment 1 of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1.

Hereinafter, Embodiment 1 of the present invention will be described on the basis of Fig. 1 to Fig. 4. However, in each of the following drawings, identical or equivalent members and portions will be described with the same reference numerals. Fig. 1 is a sectional view showing an electromagnet device for a starter according to Embodiment 1 of the present invention. Fig. 2 is a sectional view showing a shock absorbing member in the electromagnet device for the starter according to Embodiment 1 of the present invention. Fig. 3 is a front view in which the shock absorbing member in the electromagnet device for the starter according to Embodiment 1 of the present invention is seen from the left direction of Fig. 2. Fig. 4 is a characteristic view showing distance and magnetic attractive force between facing surfaces of a movable core and a fixed core and repulsive force of the shock absorbing member of the electromagnet device for the starter according to Embodiment 1 of the present invention.

In the respective figures, reference numeral 1 denotes a yoke made of a magnetic material, which forms an outer circumferential portion and constitutes a magnetic circuit; 2 denotes an excitation coil made of a conductive material, which is arranged on the inner circumferential side of the yoke 1 and is wound around a winding frame 3 made of an insulating material; 4 denotes a movable core made of a magnetic material, which is arranged on the inner circumferential side of the excitation coil 2; and 5 denotes a fixed core made of a magnetic material, which is fitted to the yoke 1 and is arranged in face-to-face relation with the movable core 4. The movable core 4 includes an engaging member 6 and a biasing spring 7. The biasing spring 7 biases an axial shift lever (not shown in the drawing) to a direction of the fixed core 5 when the amount of movement of the movable core 4 to the direction of the fixed core 5 is larger than the amount of movement of the engaging member 6 to the direction of the fixed core 5. Reference numeral 8 denotes a return spring located between the fixed core 5 and the movable core 4 and biases the movable core 4 to the axial shift lever side (not shown in the drawing).

Furthermore, as one example, the drawing shows the case where an electromagnetic relay in which the yoke 1 is shared is coaxially provided in series on the inner circumferential side of the yoke 1. The electromagnetic relay includes a plunger 9 made of a magnetic

material, which constitutes a magnetic circuit; a coil 10 made of a conductive material, which is wound around a bobbin 11 made of an insulating material; a first core 12 made of a magnetic material, which constitutes a magnetic circuit; a second core 13 made of a magnetic material, which constitutes a magnetic circuit; a rod 14 coupled to the plunger 9; a return spring 15 which biases the rod 14 and the plunger 9 to the right direction; a terminal block 16 to which a battery terminal 17 and a motor terminal 18 are attached; a movable contact 19 coupled to the rod 14; and a contact spring 20 which biases the movable contact 19.

By the way, a convex shaped portion 21 is formed on either one side of facing surfaces of the movable core 4 and the fixed core 5; and a concave shaped portion 22 is formed on the other side thereof, the concave shaped portion 22 being a substantially similar shape to the convex shaped portion 21 and having a through hole 23 in the center thereof. As an example, the drawing shows the case where the convex shaped portion 21 is formed on the movable core 4 on the surface side facing the fixed core 5, and the concave shaped portion 22 is formed on the fixed core 5 on the surface side facing the movable core 4.

Furthermore, the convex shaped portion 21 and the concave shaped portion 22 are formed in a circular truncated cone shape with a substantially similar shape, and the convex shaped portion 21 is configured in a shape which is slightly smaller than the concave shaped portion 22 so that the convex shaped portion 21 does not come in contact with the concave shaped portion 22 when the movable core 4 moves to the direction of the fixed core 5.

Reference numeral 24 is a shock absorbing member to be attached to the concave shaped portion 22. The shock absorbing member 24 has a shock absorbing portion 24a which is located on the concave shaped portion 22; a shaft portion 24b; a retained portion 24c which is passed through the through hole 23, is provided on an opposite side to the shock absorbing portion 24a, and protrudes in an outer circumferential direction from the through hole 23; and a hollow portion 24d.

The shock absorbing portion 24a of the shock absorbing member 24 has an outer diameter which is larger than an inner diameter of the through hole 23 formed in the fixed core 5 and smaller than an inner diameter of the concave shaped portion 22, and is formed in a shape having a substantially the same thickness as a depth of the concave shaped portion 22. The shaft portion 24b of the shock absorbing member 24 connects the shock absorbing portion 24a and the retained portion 24c. The retained portion 24c of the shock absorbing member 24 is composed of a plurality of protrusion portions protruded from the shaft portion 24b in the outer circumferential direction from the through hole 23.

The shock absorbing member 24 is formed in a shape that an outer diameter on the tip end side 24cl of the retained portion 24c is smaller than an inner diameter of the through hole 23 and an outer diameter on the back end side 24c2 of the retained portion 24c is larger than the inner diameter of the through hole 23. The retained portion 24c of the shock absorbing member 24 is composed of three protrusion portions as shown in Fig. 3; however, any number of the protrusion portions may be permissible; and the retained portion 24c is not formed in a protrusion shape, but the entire circumferential shape may be formed in an umbrella shape having the same outer diameter. Furthermore, there is shown the case where the hollow portion 24d is opened on the shock absorbing portion 24a side and is closed on the retained portion 24c side, but the hollow portion 24d may be formed vice versa or may be formed by a through hole.

The shock absorbing member 24 is attached to the concave shaped portion 22 formed on the fixed core 5 before the fixed core 5 is fixed to the yoke 1 or before the movable core 4 is inserted to the inner circumferential side of the excitation coil 2. The retained portion 24c is inserted to the through hole 23 from a direction of the concave shaped portion 22 and is pressed until the retained portion 24c is passed through the through hole 23; and accordingly, attachment of the shock absorbing member 24 is performed.

Next, the distance and the magnetic attractive force between the facing surfaces of the movable core 4 and the fixed core 5 and the repulsive force of the shock absorbing member 24 will be described on the basis of Fig. 1 and Fig. 4. In Fig. 4, reference letter A denotes the size of the magnetic attractive force and the repulsive force; B denotes movement distance of the movable core 4. The distance between the movable core 4 and the shock absorbing member 24 is X, and the distance between the movable core 4 and the fixed core 5 is Y. When voltage is applied to the excitation coil 2, current flows through the excitation coil 2 and the movable core 4 moves to the direction of the fixed core 5; however, the position of the movable core 4 in Fig. 1 is a static state where voltage is not applied to the excitation coil 2.

X and Y in Fig. 4 are the same values as those in Fig. 1, X denotes the distance between the movable core 4 and the shock absorbing member 24; and Y denotes the distance between the movable core 4 and the fixed core 5. Magnetic attractive force P is the magnetic attractive force between the movable core 4 and the fixed core 5. Repulsive force Q is one in which the repulsive force of the shock absorbing member 24 generated in the case where the movable core 4 moves while compressing and deforming the shock absorbing member 24 and repulsive force of the return spring 8 are added together.

Right after the voltage is applied to the excitation coil 2, the amount of movement of the movable core 4 is 0 and is shown in a state at the left end in the characteristic view of Fig. 4. The movable core 4 moves to the direction of the fixed core 5 by the magnetic attractive force P between the movable core 4 and the fixed core 5, the magnetic attractive force P being generated by the voltage applied to the excitation coil 2. During the amount of movement of the movable core 4 is smaller than X, only the repulsive force of the return spring 8 is applied; and when the amount of movement of the movable core 4 is larger than X, the repulsive force of the shock absorbing member 24 is applied. The shock absorbing portion 24a of the shock absorbing member 24 is incorporated in the concave shaped portion 22 to regulate the amount of deformation; and therefore, as shown in the characteristic view of Fig. 4, the repulsive force Q rapidly rises with respect to the amount of movement of the movable core 4. Z denotes movement distance until the movable core 4 comes to rest, and a position where the repulsive force Q and the magnetic attractive force P are in balance.

In the thus configured electromagnet device for the starter, the shock absorbing member 24 is configured to be provided between the facing surfaces of the movable core 4 and the fixed core 5; and accordingly, collision sound of the movable core 4 and the fixed core 5 can be reduced.

Further, the shock absorbing member 24 is configured to be arranged in the concave shaped portion 22 and the through hole 23 of the fixed core 5, and the retained portion 24c is formed on the shock absorbing member 24; accordingly, the shock absorbing member 24 is regulated in movement in both radial and axial directions and can be reliably fixed, and the amount of deformation to a radially outer circumference of the shock absorbing member 24 is regulated and the repulsive force increases; and therefore, variation of the amount of movement of the movable core 4 can be suppressed even when the size of magnetic attractive force P is varied.

Additionally, since the convex shaped portion 21 and the concave shaped portion 22 are formed in a substantially truncated cone shape with a similar shape, a radial gap between the convex shaped portion 21 and the concave shaped portion 22 increases when the convex shaped portion 21 moves in a direction apart from the concave shaped portion 22. Therefore, radial frictional force of the shock absorbing member 24 reduces and thus movement resistance in the case where the movable core 4 returns to a stationary position can be reduced.

Besides, the repulsive force Q of the shock absorbing member 24 is larger than the magnetic attractive force P between the movable core 4 and the fixed core 5; therefore, the movable core 4 does not directly come in contact with the fixed core 5, and thus the collision sound of the movable core 4 and the fixed core 5 can be reduced as compared to the case where the movable core 4 directly comes in contact with the fixed core 5.

Furthermore, the hollow portion 24d is formed in the shock absorbing member 24, and the retained portion 24c is composed of the plurality of protrusion portions; and accordingly, insertion resistance in the case of inserting the retained portion 24c to the through hole 23 can be reduced without reducing fixing force of the shock absorbing member 24.

Incidentally, the above described Embodiment 1 has described the case of the electromagnet device for the starter in which the electromagnetic relay is configured coaxially in series. However, an electromagnet device for a starter in which an electromagnetic relay is configured separately may be permissible; or an electromagnet device for a starter in which an electromagnetic relay is configured separately from a starter may be permissible. In addition, the description has been made on the case where the convex shaped portion is formed on the movable core side and the concave shaped portion is formed on the fixed core side. However, a configuration in which a concave shaped portion is formed on a movable core side, a convex shaped portion is formed on a fixed core side, and a shock absorbing member is provided on the concave shaped portion may be permissible; and the same effects can be exhibited as in Embodiment 1.

While the presently preferred embodiments of the present invention have been shown and described. It is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.

WHAT IS CLAIMED IS:

[1] An electromagnet device for a starter, comprising: a yoke which forms an outer circumferential portion;

an excitation coil which is arranged on an inner circumferential side of said yoke;

a movable core which is arranged on an inner circumferential side of said excitation coil; and

a fixed core which is fitted to said yoke and is arranged in face-to-face relation with said movable core,

wherein either one side of facing surfaces of said movable core and said fixed core is formed with a convex shaped portion, and

the other side thereof is formed with a concave shaped portion which is a substantially similar shape to the convex shaped portion and has a through hole in the center thereof,

the concave shaped portion being attached with a shock absorbing member,

said shock absorbing member being composed of a shock absorbing portion located on the concave shaped portion and a retained portion passed through the through hole and provided on an opposite side to the shock absorbing portion.

[2] The electromagnet device for the starter according to claim 1,

wherein the convex shaped portion and the concave shaped portion are formed in a substantially circular truncated cone shape.

[3] The electromagnet device for the starter according to claim 1 or 2,

wherein repulsive force of said shock absorbing member is larger than magnetic attractive force of said movable core and said fixed core.

[4] The electromagnet device for the starter according to claim 1 or 2,

wherein the retained portion of said shock absorbing member is composed of a plurality of protrusion portions which protrude in an outer circumferential direction from the through hole.