JP2000091055A - Cover-spark plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure for strongly fixing a cover-spark plug with a spark plug. SOLUTION: A figure (b) shows a groove 25 and a straight part 31 in this case, and a cap main body having mass is vibrated, but a time lag is generated between a screw type terminal 16, and appeared as an amplitude V. As a result, the straight part 31 is relatively moved in the vertical direction in full width W of the groove 25. Since W=d+V, an anxiety that an upper side wall 27 is scraped by the hard straight part 31 is not generated. Figures (b), (c) are examples for reference. In a figure (d), relatively soft side walls 101, 102 are locally deformed into a tadpole shape. In this condition, a large force is necessary to draw a plug cap. On this point, in the figure (b), since the groove 25 is not deformed, the straight part 31 can be smoothly moved and malfunction is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plug cap for connecting to a spark plug of an internal combustion engine, and more particularly to a plug cap integrated with an ignition coil.

[0002]

2. Description of the Related Art Spark plugs are JIS B 8031.
As defined in (Spark plug for internal combustion engine), there are a "plug with screw type terminal" in which the terminal portion is a screw and an "plug with integral terminal" in which the terminal portion has a small head and neck. The types of these terminals are determined so that the plug caps at the tips of the power supply cables engage with each other.

[0003] Regarding a plug with a screw terminal, for example,
JP-A-5-205844, entitled "Coil spring locking structure of high voltage terminal in engine ignition device", and a plug with an integral terminal are disclosed in, for example, JP-A-7-10604.
No. 8 "Ignition cable connection fitting" is available.

In FIG. 14 of the above publication, a conductive coil spring 5 is brought into contact with the head terminal 4 of the spark plug 3 so that the spark plug 3 is connected to the high-voltage terminal 2 of the high-pressure tower 1.
(See paragraph [0002] of the same publication), and is an invention in which the method of attaching the coil spring 5 to the high voltage terminal 2 is improved.

In the above, as shown in FIG. 1 of the publication, the engaging members 14b, 14b protruding from the C-shaped spring 14a are engaged with the terminal fitting 3a. FIG. 7 shows an improved invention of a tip engaging portion of a conventional long plug cap 100 shown in FIG. Reference numeral 109 in FIG. 7 is a rain cap, which is a member for preventing dust and water from entering the spark plug mounting hole 2.

[0006]

In the above description, although the coil spring 5 is drawn large with respect to the head terminal 4 in FIG. 14, it is not clear, but if the coil spring 5 is locked to the head terminal 4, Then, since the coil spring 5 can expand and contract in the axial direction based on the high voltage terminal 2, it does not seem that the high voltage tower 1 can be fixed to the ignition plug 3 stably.

In the above, as shown in FIG. 7 of the publication, the plug cap 100 is sufficiently long so that the upper end swings greatly.
Therefore, it is considered that measures are taken by fixing to the engine head 1. If the seal cap 109 is a soft material, it must be stopped with another bracket.

Both of the above are insufficient in that the plug cap is firmly fixed to the spark plug. Therefore, an object of the present invention is to provide a structure capable of firmly fixing a plug cap with a spark plug.

[0009]

According to a first aspect of the present invention, there is provided a plug cap for connecting to a spark plug having a terminal portion which is a screw-type terminal, wherein the plug cap is a conductive cylinder which covers the terminal portion. Part, a groove cut into the cylindrical part from the outer peripheral surface toward the center at a certain depth, and a spring pin set in this groove, with a cap of a type that engages the spring pin with the screw type terminal. Yes,
In addition, the width W of the groove is set to the following value.

[0010]

(Equation 3)

A groove is cut into the cylindrical portion at a constant depth from the outer peripheral surface toward the center, a spring pin is set in the groove, and the spring pin is engaged with the screw type terminal. By force, the cap can be firmly fixed to the spark plug.

In addition, since the groove width is widened by a predetermined dimension and the spring pin can be moved to some extent in the axial direction of the spark plug, the plug cap can be freely vibrated based on the spark plug. If the groove width is almost the same as the diameter of the spring pin, when a vibration difference occurs between the spark plug and the plug cap due to engine vibration, the groove is cut with a hard spring pin and spreads locally, There is a possibility that the groove may be in a tadpole shape. In this regard,
Since the lateral groove is widened, the groove is not cut by the spring pin, and the shape of the groove does not change. When the groove is in the shape of a tadpole, the spring pin becomes difficult to move in a direction away from the bottom of the groove, and there is a possibility that the force for removing the plug cap becomes excessive. At this point, if the shape of the groove does not change, the spring pin moves smoothly away from the bottom of the groove, and the plug cap can be easily removed.

According to a second aspect of the present invention, the groove is a V-shaped cross-sectional groove having a width W as a bottom width. If the side wall is inclined as compared to a groove having a straight cross section, the spring pin is easily separated from the bottom of the groove. Therefore, with a small force,
The plug cap can be detached from the spark plug, and the inspection and replacement of the spark plug can be efficiently performed.

A third aspect of the present invention is to provide a cylindrical case with a primary coil,
In an ignition coil integrated plug cap for accommodating a secondary coil and connecting to a spark plug with a screw terminal, the plug cap has a conductive cylindrical portion to cover the screw terminal, and the cylindrical portion extends from the outer peripheral surface toward the center. And at least two grooves cut at a constant depth, and a spring pin set in each of the grooves, and a cap of a type in which these spring pins are engaged with the screw type terminals, and the width of the groove is It is characterized in that W is a value determined as follows.

[0015]

(Equation 4)

The ignition coil integrated plug cap has a built-in step-up transformer function in the plug cap, so that a conventional high tension cord can be switched to a low tension cord. Will be easier.
However, due to the built-in ignition coil,
The plug cap is large and heavy. However, since two spring pins are attached to the cylindrical portion, and these pins are made to bite into the screw terminals, the attachment becomes strong.
Since the mounting is strong, there is no need to use a bracket for fixing the plug cap to the cylinder head or the like, which has been conventionally used, and the work of attaching and detaching the plug cap is simplified because there is no conventional bracket.

According to the fourth aspect, the groove is a groove having a width in the form of a bottom having a width W as a bottom, and when the cylindrical portion is pulled out of the side wall of the groove from the terminal portion of the spark plug, the spring pin is formed. The contact side is inclined. Since the groove has a groove-shaped cross section, the spring pin can easily separate from the bottom of the groove when pulling out the plug cap from the spark plug. Therefore, the plug cap can be pulled out with a small force, and the operation of removing the plug cap is simplified.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing a relationship between a plug cap (first embodiment) and a spark plug according to the present invention. A spark plug 10 is a plug with a screw terminal, and includes a center electrode 11, an outer electrode 12, and a mounting screw portion. 13,
This is a standard internal combustion engine spark plug including a nut portion 14, an insulator 15, and a screw terminal 16 as a terminal portion. In the plug cap 20, reference numeral 21 denotes a high tension cord, reference numeral 22 denotes an insulating cap main body, and reference numeral 23 denotes a conductive cylindrical portion (hereinafter, simply referred to as a "cylindrical portion").

FIG. 2 shows a plug cap (first embodiment) according to the present invention.
FIG. 11 is a cross-sectional view of the mounting state of the embodiment). A spring pin 30 is set in a groove 25 cut at a constant depth from the outer peripheral surface 24 toward the center at the tip (lower end) of the cylindrical portion 23. The pin 30 is adapted to bite into the screw of the screw terminal 16.

FIGS. 3A and 3B are views showing how to attach a spring pin according to the present invention. In FIG.
So-called hairpin-shaped spring pins 3
Bring 0. Spring pin 30 is straight part 31
And a curved portion 32 turned back from one end of the straight portion 31. The spring is made of spring steel and is sufficiently harder than ordinary carbon steel or stainless steel. At (b), the straight portion 31 is bitten into the groove 25,
The curved portion 32 is wound around the cylindrical portion 23, and an excess portion shown by an imaginary line is cut off with a tool. Thus, the straight portion 31 can move to the left in the drawing along the groove 25, but if there is no external force, the bottom 26 of the groove 25 is pushed as shown in the figure.

FIG. 4 is an enlarged view of the groove according to the first embodiment of the present invention. The groove 25 according to the first embodiment is a straight groove having a bottom 26, an upper side wall 27, and a lower side wall 28. Yes,
The width of the groove 25 is W, the spring pin 30 (more precisely,
When the diameter of the straight portion 31) is d, and V is the amplitude of the plug cap based on the spark plug, which is generated due to engine vibration, W = d + V. More specifically, in the case of a 600 cc class water-cooled in-line four-cylinder internal combustion engine in which four 150 cc class cylinders are arranged in series, the amplitude V is 0.1 to 0.3 mm, and the pin diameter d is 0.1 mm.
9 mm. Therefore, the width W of the groove is 1.0 to 1.2 mm
Should be selected from the range.

The operation of the above-described plug cap (first embodiment) will now be described. FIGS. 5A to 5D are views for explaining the operation of the plug cap (first embodiment) of the present invention. (C) and (d) are comparative examples. (A)
The straight portion 31 bites into the screw terminal 16,
This indicates that the straight portion 31 vibrates as shown by the arrow together with the screw terminal 16 with the vibration of the engine. (B) shows the groove 25 and the straight portion 31 of the present embodiment, and the cap body also vibrates because it has a mass, but a time delay occurs with the screw type terminal 16 and the amplitude V Appears as. As a result, the straight portion 3
1 moves up and down relative to the full width W of the groove 25. However, since W = d + V, there is no strong contact with the side wall 27 above the groove 25. Thus, there is no fear that the upper side wall 27 is shaved by the hard straight portion 31. The same applies to the lower side wall 28.

(C) is a comparative example, and shows that the width of the groove 100 is almost the same as the diameter of the straight portion 105.
The straight portion 105 moves relatively up and down with the delay of the vibration, and strikes the upper side wall 101 and the lower side wall 102. As a result, the relatively soft side walls 101 and 102 are locally deformed as shown in FIG.
It has a so-called tadpole shape.

In the drawing, the movement of the straight portion 105 to the right in the drawing is the biting side, and the movement to the left is the slack side. When the tubular portion 106 is attached or detached, the movement to the left is indispensable. However, in the above (d), since the straight portion 105 is fitted in the concave portion 107, it is necessary to apply a considerably large force to move the straight portion 105 as shown by the arrow. Therefore, in the structure (c), an excessively large force must be applied when removing the cylindrical portion 106, that is, when removing the plug cap from the spark plug, and there is a possibility that a relatively thin screw terminal may be damaged. Is not preferred. In this regard, in the case of (b) above, since the groove 25 is not deformed, the straight portion 31 smoothly moves to the left in the figure, and the above-described inconvenience does not occur.

FIGS. 6A to 6C are views showing the shape of the groove of the plug cap (second embodiment) according to the present invention. In the second embodiment, as shown in (a), the width of the bottom of the groove 25 is W, but the lower side wall 28 is inclined at an angle θ (for example, 15 °) to form an overall R-shaped cross-sectional groove. It is characterized by the following. (B) shows a state in which the straight portion 31 is engaged with the screw terminal 16. At this time, the straight part 31
And the lower side wall 28 form a V-shape at an angle α. The angle of the thread 17 is generally 60 °, and the angle α may be 45 ° obtained by adding the angle θ (15 °) to half of 30 °.

Therefore, in (c), when the tubular portion 23 is to be pulled out in the direction of the white arrow, the straight portion 31 is bid out at a V-shape of the angle α, and the straight portion 31 is easily drawn as shown by the arrow. It moves toward the outer peripheral surface 24. Therefore, the plug cap can be more easily pulled out of the spark plug than in the first embodiment shown in FIG.

In order to exhibit this effect, θ is 10 to 45.
You can choose from the range of °. If the angle is less than 10 °, there is no difference from the straight groove, and the force for pushing the straight portion 31 out is reduced. If the angle exceeds 45 °, the straight portion 31
In addition to constantly applying a leftward force to the plug, the clearance between the straight portion 31 and the groove 25 in the plug cap insertion direction when the straight portion 31 and the groove 25 are extruded to the left (outside) in the figure becomes too large, and there is a concern that the straight portion 31 becomes unstable. Occurs. It should be noted that it is more desirable to limit θ to 20 ° and to select θ from the range of 10 to 20 ° from the viewpoint of ease of production because θ is easier to make as θ is smaller.

FIGS. 7A to 7C are views showing the shape of the groove of the plug cap (third embodiment) according to the present invention. In the third embodiment, as shown in (a), the width of the bottom 26 of the groove is W, but the upper and lower side walls 27 and 28 are inclined at angles β and β to form a V-shaped cross-sectional groove as a whole. It is characterized by. The angle β may be the same as the angle θ. In (b), when the cylindrical portion 23 is pushed down as indicated by the outline arrow, the straight portion 31 smoothly moves along the upper side wall 27 toward the outer peripheral surface 24 of the cylindrical portion 23, so that the plug cap can be easily sparked. Can be mounted on plugs. In (c), when the cylindrical portion 23 is pulled out as indicated by a white arrow, the straight portion 31 smoothly moves along the lower side wall 28 toward the outer peripheral surface 24 of the cylindrical portion 23. Can be easily pulled out.

FIG. 8 shows a plug cap according to the present invention (fourth plug cap).
FIG. 2 is a diagram showing a relationship between the embodiment) and a spark plug. A spark plug 10 is the same plug with a screw type terminal as described in FIG. On the other hand, the plug cap 40 includes the first coil 42 and the second coil 4
3. The first coil 42 and the second coil 4 which house the cylindrical portion 23
3 is a so-called plug plug integrated with an ignition coil, which constitutes a step-up transformer for ignition (spark ignition). Since the first coil 42 and the second coil 43 having a required length must be wound, the length is elongated.

FIG. 9 is a detailed view of part 9 of FIG.
The first groove 25A and the second groove 25B are cut in parallel at a predetermined distance L, and the first spring pin 30A,
This shows that the second spring pin 30B is attached. First
The groove 25A and the second groove 25B have the same shape as the groove 25, but the first, second, and A and B are added for distinction.
First spring pin 30A, second spring pin 30B
Is also the same pin as the spring pin 30, but the first, second and A and B are added for distinction. The first and second grooves 25A, 25B are both L-shaped grooves in which the lower side walls 28, 28 are inclined. Since the groove has a L-shaped cross section, a little force is required for mounting, but it is easy to pull out.

However, the first and second grooves 25A and 25B are
Both may be V-shaped cross-sectional grooves. With a V-shaped cross-section groove, both mounting and pulling-out can be performed with a small force. However, since the remaining portion 29 between the first groove 25A and the second groove 25B becomes small, it cannot be used when the distance L is relatively small.

The first and second grooves 25A and 25B may be the straight grooves described with reference to FIG. This is because the force to be applied to both the mounting and pulling is large, but the working is easy, and the remaining portion 29 between the first groove 25A and the second groove 25B can be sufficiently secured. 4th
In the embodiment, the first and second grooves 25A and 25B are both basically L-shaped cross-sectional grooves, but may be V-shaped cross-sectional grooves, straight grooves, or a mixture thereof.

FIG. 10 is an operation view of the plug cap (fourth embodiment) according to the present invention, and a large moment M1 is applied to the cylindrical portion 23. However, the cylindrical portion 23 is provided with the first spring pin 30A and the second spring pin 30
B and a so-called two-point support structure fixed at two points. The one-point support structure is weak against the moment M1, but the two-point support structure can withstand a sufficiently large moment M1.

FIG. 11 is a mounting view of a plug cap (fourth embodiment) according to the present invention. The spark plug 10 is mounted on the cylinder head 51, the plug cap 40 is mounted on the spark plug 10, and the plug cap 40 is mounted.
The plug 52 has a transformer function built into the plug cap 40, so that only a low-voltage current needs to flow through the cord 52.
Can use wires much thinner than high tension cords. If the electric wire is thin, it is easy to bend and the attaching / detaching work of the plug cap 40 becomes easy. And, although the plug cap 40 is elongated, it can be firmly fixed to the spark plug 10 with the two spring pins 30A and 30B, so that there is no need to support the plug cap 40 with another bracket.

If a bracket is required, the number of parts increases because the bracket must be prepared.
There are inconveniences such as an increase in the number of steps for attaching and detaching the bracket, and the need to attach and detach the bracket every time the spark plug is inspected and replaced, which makes the inspection and replacement work troublesome. In this regard, the structure shown in FIG. 11 eliminates such troublesomeness at all.

In the fourth embodiment, the number of the grooves is two.
If the distance L has a margin, it may be three or more.
Further, since the amplitude V changes depending on the type and type of the engine, the shape and the weight of the plug cap, its value is obtained by an experiment, and the value obtained by correcting the experimental value based on experience may be determined as the amplitude V.

[0037]

According to the present invention, the following effects are exhibited by the above configuration. According to the first aspect, a groove is cut into the cylindrical portion at a constant depth from the outer peripheral surface toward the center, a spring pin is set in the groove, and the spring pin is engaged with the screw type terminal. With this spring force, the cap can be strongly fixed to the spark plug.

In addition, since the groove width is widened by a predetermined dimension and the spring pin can be moved to some extent in the axial direction of the spark plug, the plug cap can be freely vibrated based on the spark plug. If the groove width is almost the same as the diameter of the spring pin, when a vibration difference occurs between the spark plug and the plug cap due to engine vibration, the groove is cut with a hard spring pin and spreads locally, There is a possibility that the groove may be in a tadpole shape. In this regard,
Since the lateral groove is widened, the groove is not cut by the spring pin, and the shape of the groove does not change. When the groove is in the shape of a tadpole, the spring pin becomes difficult to move in a direction away from the bottom of the groove, and there is a possibility that the force for removing the plug cap becomes excessive. In this regard, if the shape of the groove does not change, the spring pin moves smoothly away from the bottom of the groove, and the plug cap can be easily removed.

According to a second aspect of the present invention, the groove is a V-shaped groove having a width W as a bottom width. If the side wall is inclined as compared to a groove having a straight cross section, the spring pin is easily separated from the bottom of the groove. Therefore, with a small force,
The plug cap can be detached from the spark plug, and the inspection and replacement of the spark plug can be efficiently performed.

According to the third aspect of the present invention, since the ignition coil integrated plug cap is employed and the plug cap has a built-in step-up transformer function, the conventional high tension cord can be switched to the low tension cord. The adoption makes it easier to attach and detach the plug cap. However, the plug cap becomes large and heavy due to the built-in ignition coil. However, since two spring pins are attached to the cylindrical portion, and these pins are made to bite into the screw terminals, the attachment becomes strong. Since the mounting is strong, there is no need to use a bracket for fixing the plug cap to the cylinder head or the like, which has been conventionally used, and the work of attaching and detaching the plug cap is simplified because there is no conventional bracket.

According to the fourth aspect of the present invention, since the groove is formed into a groove having a rectangular cross section, the spring pin is easily separated from the bottom of the groove when the plug cap is pulled out from the spark plug. Therefore, the plug cap can be pulled out with a small force,
The work of removing the plug cap is simplified.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a plug cap (first embodiment) and a spark plug according to the present invention.

FIG. 2 is a cross-sectional view showing a mounting state of a plug cap (first embodiment) according to the present invention.

FIG. 3 is a view showing how to attach a spring pin according to the present invention.

FIG. 4 is an enlarged view of a groove according to the first embodiment of the present invention.

FIG. 5 is an operation explanatory view of the plug cap (first embodiment) of the present invention.

FIG. 6 is a view showing a shape of a groove of a plug cap (second embodiment) according to the present invention.

FIG. 7 is a view showing a shape of a groove of a plug cap (third embodiment) according to the present invention.

FIG. 8 is a view showing a relationship between a plug cap (fourth embodiment) and a spark plug according to the present invention.

FIG. 9 is a detailed view of part 9 of FIG.

FIG. 10 shows a plug cap according to the present invention (fourth embodiment).
Action diagram

FIG. 11 shows a plug cap according to the present invention (fourth embodiment).
Installation drawing

[Explanation of symbols]

10 spark plug, 16 screw terminal, 20, 40
... Plug cap, 23 ... conductive cylinder part, 24 ... outer peripheral surface of the cylinder part, 25, 25A, 25B ... groove, 26 ... groove bottom, 27
... side wall above groove, 28 ... side wall below groove, 30, 30A,
30B: spring pin, 31: straight part of pin,
W: groove width, d: diameter of spring pin, V: amplitude of this plug cap with reference to the spark plug.

Claims (4)

[Claims] 1. A plug cap having a terminal portion connected to a spark plug having a screw-type terminal, wherein the plug cap has a conductive tube portion to cover the terminal portion and is fixed to the tube portion from an outer peripheral surface toward the center. And a spring pin set in the groove, a cap of a type in which the spring pin is engaged with the screw-type terminal, and the width W of the groove is set to the following value. A plug cap characterized in that: (Equation 1) 2. The plug cap according to claim 1, wherein the groove is a V-shaped cross-sectional groove having the width W as a bottom width. 3. An ignition coil integrated plug cap for accommodating a primary coil and a secondary coil in a cylindrical case and connecting to a spark plug with a screw type terminal, wherein the plug cap is a conductive cylinder to cover the screw type terminal. Portion, at least two grooves cut into the cylindrical portion from the outer peripheral surface toward the center at a constant depth, and spring pins set in each of the grooves, and these spring pins are screw-type terminals. Wherein the width W of the groove is set to the following value. (Equation 2) 4. The groove is a groove having a V-shaped cross section having the width W as a bottom width, and a spring pin contacts with a side wall of the groove when pulling out a cylindrical portion from a terminal portion of a spark plug. The side is inclined, The claim 1 or 3 characterized by the above-mentioned.
The described plug cap.