JPH06163288A - Ignition transformer - Google Patents

Abstract

PURPOSE:To prevent dielectric breakdown due to crack generation caused by the difference of coefficient of linear expansion between a shield member and insulating resin, by installing a bag type part engaging with the end surface of the shield member, on the inner end surface of a cylindrical case made of insulator. CONSTITUTION:In a cylindrical case 2 made of insulator, the following are arranged; a primary winding 5, a secondary winding 4, a core 3 which magnetically couples the winding 5 to the winding 4, a shield member 6 made of metal covering the outer peripheries of the windings 4, 5 along the inner surface of the cylindrical case 2 made of insulator, in the state that a part is dropped out along the length direction of both windings 4, 5. The case 2 made of insulator is filled with insulating resin 8, and a high voltage is led out from the secondary winding, thereby constituting an ignition transformer 1. In this case, a protruding wall 2c forming a bag type part 14 composed of soft insulating resin is interposed between the shield member 6 in the outer peripheral region of the primary winding 5 or the secondary winding 4 and the insulating resin 8. Thereby crack generation of the insulating resin is prevented, and original function can be exhibited for a long term.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition transformer, and more particularly to an ignition transformer suitable for supplying a high voltage to an ignition plug of an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in an ignition transformer having a large transformation ratio and generating a high voltage, a primary winding, a secondary winding, and both windings are magnetically coupled in a cylindrical insulator case. A core is arranged, a metallic shield member is arranged around the both windings, and an insulating case such as a hard epoxy resin is filled in the insulating case to form a metallic case, a primary winding, The dielectric strength between secondary windings etc. is improved.

However, in such an ignition transformer, the coefficient of linear expansion of the shield member is 1 ×.
About 10 ^-5 / K, the linear expansion coefficient of epoxy resin is 4 to 1
Since there is a considerable difference of about 0 × 10 ⁻⁵ / K, there is a problem that cracks occur particularly on the inner end face side of this insulating resin when temperature stress is applied.

If the insulating resin is cracked, it is
This causes dielectric breakdown between the secondary winding that generates a high voltage of about 0 KV and the shield member, and the original function of the ignition transformer cannot be maintained.

[0005]

As described above, there has been a problem in the prior art that no countermeasure against dielectric breakdown due to the difference in linear expansion coefficient between the shield member and the insulating resin is taken into consideration.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ignition transformer which has an improved structure and can eliminate the dielectric breakdown due to the occurrence of cracks due to the difference in linear expansion coefficient between the shield member and the insulating resin. is there.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a primary winding, a secondary winding, a core for magnetically coupling these windings, and a tubular insulator are provided in a tubular insulator case. A metal shield member that covers the outer circumference of both windings is arranged in a state where a part of it is missing along the length direction of both windings along the inner surface of the case. In the ignition transformer that is filled with the above and takes out a high voltage from the secondary winding, a bag-like portion that engages with the end surface of the shield member is provided on the inner end surface of the cylindrical insulating case.

[0008]

According to the ignition transformer having the above structure,
Since a part of the insulator case is interposed between the filled insulating resin and the shield member, it is possible to buffer the difference in expansion and contraction amount between the two due to the difference in linear expansion coefficient. This prevents the occurrence of cracks and maintains the function of this ignition transformer for a long period of time.

Further, since the shield member is partially missing along the length direction of both windings, it is possible to suppress eddy current and reduce power loss.

[0010]

EXAMPLES Examples of the present invention will be described below.

The ignition transformer 1 shown in FIG.
It is configured such that a high voltage is supplied to an ignition plug (not shown), and it has a substantially rectangular tube shape and is provided with a connection cord attachment portion 2a for an ignition plug at one end and an opening at the other end. Body case 2 and a rod-shaped core 3 housed in a core case 3a arranged at the center of the insulator case 2.
A secondary winding 4 wound around a bobbin 4a arranged on the outer periphery of the core 3, and a bobbin 5 arranged on the outer periphery of the secondary winding 4.
a primary winding 5 wound around a and a metal that can be mounted outside the primary winding 5 and inside the insulator case 2 that is placed in close contact with the inner wall 2b of the insulator case 2. And a plate-shaped shield member 6, a piece 7a connected to the secondary winding 4, and a piece 7a of the secondary connecting conductor 7 having another piece 7b arranged at a right angle facing the piece of connecting cord 2a. The core 3, the secondary winding 4, the primary winding 5, which is filled in the metal case 2,
The insulating member 8 is made of an epoxy resin that insulates each of the shield member 6 and the insulator case 2.

In FIG. 1, reference numeral 9 denotes a substantially cylindrical secondary bobbin for winding the secondary winding 4 and mounting the secondary connecting conductor 7, and 10 denotes a substantially cylindrical shape for winding the primary winding 5. It is a primary bobbin.

As shown in FIGS. 2 and 3, a secondary winding 4 and a primary winding 5 are formed on a part of the inner wall 2b of the insulator case 2.
The central portion is connected to the inner wall 2b along the length direction of the guide plate 11, and a guide plate 11 having a certain width in the vertical direction and spaced a minute distance from the inner wall 2b is arranged.
And the inner wall 2b form a pair of upper and lower guide grooves 12a and 12b along the length direction of the secondary winding 4 and the primary winding 5.

Further, as shown in FIGS. 2 and 3, a projecting wall 2c is provided along the inner peripheral direction of the inner wall 2b at the deepest portion of the guide grooves 12a, 12b in the insulator case 2. There is. As a result, the bag-shaped portion 1 for inserting the end portion of the shield member
4 is forming.

As shown in FIG. 3, the shield member 6 is formed in a cylindrical shape that can be inserted along the inner wall 2b of the insulator case 2, and the guide groove 12a is formed in the center of the upper side thereof. , 12b are provided with cut-off portions 6a cut along the length direction. The tip edge 6b of the shield member 6 is inserted into the bag-shaped portion 14 provided on the inner end surface of the case 2.

On the end side of the primary bobbin 10,
A step portion 10a is provided which engages with the end portion of the shield member 6 when the primary bobbin 10 is mounted in the insulator case 2.

The insulating resin forming the case body 2 is made of a relatively soft material (for example, the linear expansion coefficient is 2 to 3 × ^-5 /
However, the filling resin is made of a hard material (for example, the linear expansion coefficient is 1 × 1) in order to secure the pressure resistance.
Needless to say, the one selected is about 0 ⁻⁵ / k).

Next, the above-mentioned ignition transformer 1
The action of will be explained.

According to this ignition transformer 1,
Since the projecting wall 2c of the case body 2 made of soft insulating resin is interposed between the shield member 6 and the hard insulating resin 8 in the outer peripheral region of the primary winding 5 or the secondary winding 4, the insulating resin 8 and the shield are provided. It is possible to buffer the difference in the amount of expansion and contraction between the member 6 and the member 6 due to the difference in the linear expansion coefficient as described above, and as a result, the occurrence of cracks in the insulating resin 8 can be prevented and the function of the ignition transformer 1 can be maintained for a long time. Can be maintained across.

Further, since the shield member 6 has the cutout portion 6a along the lengthwise direction of both the windings 4 and 5, the eddy current due to the magnetic coupling between the primary winding 5 and the secondary winding 4 is suppressed and the power is reduced. You can reduce the loss.

Further, considering the assemblability of the ignition transformer 1, the notch 6a of the shield member 6 is aligned with the guide grooves 12a, 12b of the insulator case 2 at the time of assembly, as shown in FIG. Meanwhile, the shield member 6 can be positioned at a predetermined position by inserting the shield member 6 into the insulator case 2 and further inserting the insertion tip of the shield member 6 into the bag-shaped portion 14. . Next, the primary bobbin 1 is inserted by inserting the primary bobbin 10 into the insulator case 2 and engaging the step portion 10a of the primary bobbin 10 with the end portion of the shield member 6.
0, and therefore the positioning of the primary winding 4 can also be easily performed.

The present invention can be modified in various ways within the scope of the invention in addition to the above-mentioned embodiment. For example, in the above-described embodiment, the insulator case and the shield member have a rectangular tube shape, but they may have a cylindrical shape.

[0023]

According to the present invention described in detail above, since it is configured as described above, it is possible to buffer the difference in expansion and contraction amount between the insulating resin and the shield member, prevent cracking of the insulating resin, and prevent long-term occurrence. It is possible to provide an ignition transformer capable of maintaining the original function over the entire range.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of an ignition transformer of the present invention.

FIG. 2 is a sectional view of an insulator case of the ignition transformer of the present embodiment.

FIG. 3 is an exploded perspective view of an insulator case and a shield member of the ignition transformer of this embodiment.

[Explanation of symbols]

 1 Ignition transformer 2 Insulator case 3 Core 4 Secondary winding 5 Primary winding 6 Shield member 8 Insulating resin 14 Bag-shaped part

Claims (1)

[Claims] 1. A primary winding in a tubular case made of an insulator,
The secondary winding and the core that magnetically couples these windings, and both windings in a state in which a portion along the inner surface of the cylindrical insulator case is missing along the length direction of both windings In the ignition transformer for arranging a metal shield member that covers the outer periphery of the insulating case and filling the inside of the insulating case with an insulating resin to extract a high voltage from the secondary winding, the cylindrical insulating case is used. An ignition transformer, wherein a bag-shaped portion that engages an end surface of the shield member is provided on an inner end surface of the ignition transformer.