An electromagnetic coil apparatus

Abstract: An electromagnetic coil apparatus which has an electromagnetic coil for genarating an elecrto-magnetic flux. The electromagnetic coil includes a coil bobbin and a coil wire, and a coil wire is wound on the coil bobbin. A coil wire end is picked up from the electromagnetic coil. An elastic terminal cap is connected to the coil bobbin. The coil wire end is arranged between the terminal cap and the coil bobbin. The terminal cap discharges a stress from the coil wire end.

Description: BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates generally to an electromagnetic coil apparatus. More particularly, the present invention is concerned with an improved structure of the apparatus which is not affected by terminal change therearound. 2. Description of the related art An electromagnetic coil apparatus is often used in, for example, a hydraulic control circuit for controlling a hydraulic flow. A conventional electromagnetic coil apparatus is diclosed in Figs. 4 and 5. Referring now to Fig. 4, an electromagnetic coil apparatus 50 basically includes a coil bobbin 51, an electric coil 52, an electric terminal 53 and an outer housing 54. The coil bobbin 51 forms a center hole 51a and the electric coil 52 is wound on the coil bobbin 51. The electric coil 52 is comprised of an electric wire 52a, and an electric wire end 52b is molded into the outer housing 54. The outer housing 54 forms a cylindrical connecting portion 54a. A valve assembly (not shown) is, for example, arranged in the center hole 51a. The electric terminal 53 is molded into the coil bobbin 51 and the outer housing 54. The outer housing 54 is formed on the the coil housing and the coil bobbin 51, and the electric wire end 52b is molded into the outer housing as described above. A specific construction of the electric wire end portion 52b is shown in Fig. 5. That is to say, the electric wire end 52b is entirely molded into the outer housing 54. In operation, the electromagnetic coil apparatus 50 is generally arranged under high vibrated and/or high temperature condition. As a result, an expansion or contraction of the electric wire end 52b and the electric terminal 53 will be released. However, there are problems with the above-described design. For example, if these operating conditions are maintained, the electric wire end 52b and/or the outer housing 54 have possibilities to be broken. Once the electromagnetic coil apparatus 50 is broken, the normal operation will be obstructed. SUMMARY OF THE INVENTION Accordingly, it is one of the primary objects of the present invention to provide an electromagnetic coil apparatus which discharges a stress from the end of the electric wire. It is another object of the present invention to provide a long-lifed applicable electromagnetic coil apparatus. It is still a further object of this invention to produce an electromagnetic coil apparatus to solve the above-described drawbacks of the conventional electromagnetic coil apparatus. Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in connection with the accompanying drawings. To achieve the above objects, and in accordance with the principles of the invention as embodied and broadly described herein, an electromagnetic coil apparatus of the aforementioned conventional type is characterized in that a terminal cap composed of an elastic element is connected to the projecting portion and that a coil wire end picked up from the electromagnetic coil is arranged between the terminal cap and the projecting portion and is fitted to the side wall of the projecting portion by the elastic force of the terminal cap. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 represents a cross sectional view of an electromagnetic coil apparatus of the first embodiment. Fig. 2 represents an enlarged view of the encircled portion I of the Fig. 1 of the first embodiment. Fig. 3 represents a cross sectional view of an electromagnetic coil apparatus of the second embodiment. Fig. 4 represents a cross sectional view of an electromagnetic coil apparatus of the prior art. Fig. 5 represents an enlarged view of the encircled portion II of the Fig. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the preferred embodiment, an electromagnetic coil apparatus 10 may be used, for example, in an hydraulic control circuit of an automobile. Fig. 1 shows a cross sectional view of a first embodiment of the electromagnetic coil apparatus 10, Fig. 2 shows a partially enlarged view of an encircled portion I in Fig. 1 and Fig. 3 shows a cross sectional view of a second embodiment of the electromagnetic coil apparatus 10 of the present invention. Figs. 1 and 2 show the first embodiment of the present invention. Referring to Fig. 1, the electromagnetic coil apparatus 10 basically includes a coil bobbin 11, an electromagnetic coil 12, a coil housing 13, an electric terminal 14, a terminal cap 15 and an outer housing 16. The coil bobbin 11 forms a center hole 11a and a valve assembly (not shown) is arranged therein. The electromagnetic coil 12 is composed of a coil wire 12a, and the coil wire 12a is wound up on the coil bobbin 11. A coil wire end 12b of the coil wire 12a is picked up from the electromagnetic coil 12. The coil bobbin 11 has a projecting portion 11b, and the electric terminal 14 is molded in the coil bobbin 11 as one body. The electric terminal 14 is of an L-shaped configuration. The terminal cap 15 is connected with the projecting portion 11b of the coil bobbin 11. The terminal cap 15 is made of an elastic element, for example rubber or other similar material. The terminal cap 15 has a concave portion 15a, and the concave portion 15a is connected with the projecting portion 11b. The picked up coil wire end 12b is fitted to the side wall 11c of the projecting portion 11b by an elastic force of the terminal cap 15. The outer housing 16 is molded on the outer portion of the terminal cap 15 and the coil housing 13. The outer housing 16 and a partial surface of the terminal cap 15 define a cylindrical connecting portion 17. Referring to Fig. 2, the coil wire end 12b is arranged between the coil bobbin 11 and the terminal cap 15. The coil wire end 12b is fitted to the side wall 11c of the projecting portion 11b by an elastic force of the terminal cap 15. To reduce a frictinal force, a coating material can be provided on the surface of the coil wire end 12b. A second embodiment of the present invention will be described with reference to Fig. 3. Since the basic construction of the second embodiment is similar to that of the first embodiment of the present invention, only differences therebetween will be described in the following description. As shown in Fig. 3, the L-shaped electric terminal 14 is molded within the coil bobbin 11. The terminal cap 15 is connected with the projecting portion 11b of the coil bobbin 11. The electric terminal 14 is fully molded in the terminal cap 15, and the coil wire end 12b is arranged between the terminal cap 15 and the projecting portion 11b. A side surface of the terminal cap 15 forms a cylindrical connecting portion 17. The terminal cap 15 is made of an elastic element, for example rubber or another similar material. A coating material can be provided on the surface of the coil wire end 12b for reducing stress, if necessary. The basic operation of this embodiment is similar to that of the conventional electromagnetic coil apparatus described earlier, that is, electrical energy causes an electromagnetic valve (not shown) to operate in opening and closing manner. As is evident from the above description, when a hydraulic path is controlled within the electromagnetic valve, a vibration and/or a heat are given to the electromagnetic coil apparatus 10. In operation, if high vibration and/or high temperature are given to the electromagnetic coil apparatus 10, the terminal cap 15 absorbes the thermal expansion of the coil wire end 12b. That is to say, the serious problem in the prior art can be solved since the arrangement of the coil wire end acts to prevent the cutting. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood theat within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Claims: An electromagnetic coil apparatus (10) comprising : a coil bobbin (11) ; a coil wire (12a) wound on said coil bobbin (11) and constituting an electromagnetic coil (12) ; a projecting portion (11b) formed at an end portion of said coil bobbin (11), characterized in that a terminal cap (15) composed of an elastic element is connected to said projecting portion (11b) and that a coil wire end (12b) picked up from said electromagnetic coil (12) is arranged between said terminal cap (15) and said projecting portion (11b) and is fitted to the side wall (11c) of the projecting portion (11b) by the elastic force of said terminal cap (15). An electromagnetic coil apparatus (10) according to claim 1 characterized in that an outer housing (16) is arranged at an outer surface of said coil bobbin (11) and said terminal cap (15). An electromagnetic coil apparatus (10) according to claim 2 characterized in that an electric terminal (14) is molded in said terminal cap (15) and said outer housing (16). An electromagnetic coil apparatus (10) according to claim 2 characterized in that an electric terminal (14) is molded in said terminal cap (15).

Inventors: MORIOKA HIROAKI, SUZUKI SHIGEMITSU, MORIOKA, HIROAKI, SUZUKI, SHIGEMITSU
Applicants: AISIN SEIKI, AISIN SEIKI KABUSHIKI KAISHA
Application year: 1990
Main classification: H01F5
IPC codes: H01F5