CN111446627B

CN111446627B - Spark plug and manufacturing method thereof

Info

Publication number: CN111446627B
Application number: CN202010160156.1A
Authority: CN
Inventors: 杨辉睦; 李耀
Original assignee: Weichai Torch Technology Co ltd
Current assignee: Weichai Torch Technology Co ltd
Priority date: 2020-03-10
Filing date: 2020-03-10
Publication date: 2021-08-03
Anticipated expiration: 2040-03-10
Also published as: CN111446627A

Abstract

A spark plug and its preparation method, including insulator, terminal screw, central electrode, side electrode and body; wherein the insulator has a stepped hole in an axial direction; a center electrode at least partially inserted into a front end side of the stepped hole; the connecting screw rod is provided with a terminal part and a rod-shaped part, and the rod-shaped part is inserted into the stepped hole of the insulator; the length of the rod-shaped part of the wiring screw rod extending into the insulator along the axial direction is less than 35mm, a rod-shaped connecting piece is arranged between the front end of the rod-shaped part and the central electrode, the length of the rod-shaped part of the wiring screw rod is reduced by increasing the rod-shaped connecting piece, and the connection between the wiring screw rod and the central electrode is ensured. The invention limits the rod-shaped part of the screw to be less than 35mm, and extends the length of the rod-shaped part of the wiring screw through the rod-shaped connecting piece, thereby effectively shortening the length of the rod-shaped part of the wiring screw, and solving the process difficulty of the production of the wiring screw caused by the forced increase of the rod-shaped part due to the prolonged distance between the terminal part and the shell.

Description

Spark plug and manufacturing method thereof

Technical Field

The invention relates to a spark plug and a manufacturing method thereof, in particular to a spark plug and a manufacturing method thereof; the spark plug and the manufacturing method thereof can solve the process difficulty of the production of the wiring screw rod caused by the forced increase of the rod-shaped part due to the fact that the distance between the terminal part and the shell is prolonged, and the processing qualified rate is low; and the strength of the spark plug is reduced due to the bending in the production process of the insulator component; belongs to the technical field of spark plug manufacture.

Background

Conventionally, a spark plug is used to ignite a mixture in an internal combustion engine. For example, a spark plug generally includes: the insulator member is generally composed of an insulator having a shaft hole extending in an axial direction, a center electrode provided on a front end side of the shaft hole, a resistor provided in a middle portion of the shaft hole for sealing, and a wire screw provided on a rear end side of the hole. The terminal portion of the terminal screw is fitted into the rear end of the insulator, and the rod-shaped portion is inserted into the axial hole of the insulator. A metal shell is fixed to the outer periphery of the insulator, and a side electrode is welded to the front end of the shell. A gap is formed between the side electrode and the center electrode, and when a predetermined voltage is applied to the terminal screw, spark discharge is generated between the center electrode and the side electrode.

In recent years, the size and weight of an engine have been reduced, and a spark plug has been slimmed. Meanwhile, in order to obtain higher power and meet more severe emission regulations, the engine generally adopts technologies such as turbocharging and in-cylinder direct injection, so that the pressure in a combustion chamber of the engine is rapidly increased, and therefore higher voltage is required to break down the mixed gas. However, in order to solve the problem that a higher spark-over voltage more easily causes current leakage from the terminal portion of the terminal screw to the housing, thereby possibly causing ignition failure of the engine, it is known to lengthen the distance between the terminal portion of the terminal screw and the housing of the insulator, and to prevent current leakage by lengthening the distance.

In this case, the rod-like portion of the terminal screw inserted into the insulator tends to be thin and long in size. When the rod-shaped part of the wiring screw rod is too thin and too long, the processing technology of the wiring screw rod is difficult; meanwhile, the bending deformation of the wiring screw rod is easily caused in the production process, and the qualification rate is reduced.

In the manufacturing process of the insulator component, the terminal screw is usually combined with the insulator through press-fitting in a high-temperature state, and the terminal screw with the lengthened rod part is easy to cause overlarge bending amount of the rod part in the press-fitting process in the high-temperature state (about 850 ℃), so that the rod part generates radial extrusion force on the insulator, the extrusion force can generate irreversible damage on the insulator, and finally the reliability of the spark plug is reduced. Further, the possibility of damaging the insulator is further increased by the reduction in diameter of the spark plug, and therefore, it is necessary to improve this.

Through search, no relevant patent technical literature reports are found, and the most similar patent literatures comprise the following:

1. the patent number is CN201620688305.0, and the name is 'a spark plug with a cup-shaped wiring terminal', the patent discloses a spark plug with a cup-shaped wiring terminal, which comprises a wiring terminal and a ceramic rod, wherein the wiring terminal is embedded in the ceramic rod, the end top of the wiring terminal extends out of the ceramic rod, the ceramic rod is an elongated polished rod, and the wiring terminal is a T-shaped wiring terminal; the end rod of the T-shaped wiring terminal is inserted into the ceramic rod, the head of the T-shaped wiring terminal is an end top, an inward concave wiring terminal groove is formed in the center of the end top, and the wiring terminal groove is a regular frustum blind hole. Although this patent proposes to lengthen the ceramic rod and also proposes to improve the terminal, it does not improve the terminal rod length direction of the terminal, and thus the above-mentioned problems still remain.

2. Patent No. CN200780101663.0, entitled "spark plug", discloses a spark plug for igniting an air-fuel mixture in an internal combustion engine. The spark plug includes an electrode terminal extension pin, an ignition electrode, a ground electrode, a sleeve insulator, and upper and lower insulators. The firing electrode and the extension pin are axially aligned and connected. The ground electrode is adjacent the firing electrode to define a spark gap between the firing electrode and the first end of the ground electrode. A sleeve insulator surrounds the extension pin. An upper insulator surrounds the upper portion of the extension pin and is in contact with the sleeve insulator. A lower insulator surrounds the lower portion of the extension pin and is in contact with the sleeve insulator. This patent proposes an extension needle shaft, but it also proposes how to solve the aforementioned problems with extension needle shafts, and therefore the aforementioned problems still remain.

3. Patent No. CN201480071112.4 entitled "spark plug", which discloses a spark plug. Wherein the connecting part connecting the center electrode and the terminal metal fitting in the through hole of the insulator comprises: a resistor body; and a magnetic structure disposed at a position away from the resistor on the front end side or the rear end side of the resistor, the magnetic structure including a magnetic body and a conductor. The first member is a member of the resistor and the magnetic body structure disposed on the front end side, and the second member is a member of the resistor and the magnetic body structure disposed on the rear end side. The connecting portion further includes a first conductive sealing portion, a second conductive sealing portion, and a third conductive sealing portion. The first conductive seal portion is disposed on the distal end side of the first member and is in contact with the first member. The second conductive seal portion is disposed between and in contact with the first member and the second member. The third conductive seal portion is disposed on the rear end side of the second member and is in contact with the second member. The magnetic structure includes a conductive material as a conductor, an iron-containing oxide as a magnetic material, and a ceramic containing at least one of silicon, boron, and phosphorus. This patent does not propose to extend the terminal screw, but proposes to add a magnetic structure between the center electrode and the terminal metal fitting in addition to the resistor, but this magnetic structure is not intended to solve the above-mentioned problems of the present invention, but to appropriately suppress radio wave noise by both the resistor and the magnetic structure.

From the description of the above patent, it can be seen that no one has proposed how to solve the process difficulty of the production of the terminal screw due to the forced increase of the rod-shaped portion caused by the extended distance between the terminal portion and the housing, and the processing yield is low; and the strength of the spark plug is reduced due to the bending in the production process of the insulator component; it is therefore necessary to investigate this problem.

Disclosure of Invention

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a spark plug in which a distance between a terminal portion of a terminal screw and a housing is increased and a rod-shaped portion of the terminal screw is not increased, and a method for manufacturing the same; the spark plug and the manufacturing method thereof can solve the process difficulty of the production of the wiring screw rod caused by the forced increase of the rod-shaped part due to the fact that the distance between the terminal part and the shell is prolonged, and the processing qualified rate is low; and the strength of the spark plug is reduced due to the bending of the insulator component during the production process.

In order to achieve the purpose, the invention provides a spark plug, which comprises an insulator, a wiring screw rod, a central electrode, a side electrode and a shell; wherein the insulator has a stepped hole in an axial direction; a center electrode at least partially inserted into a front end side of the stepped hole; the connecting screw rod is provided with a terminal part and a rod-shaped part, the rod-shaped part is inserted into the stepped hole of the insulator, and the terminal part is leaked out of the rear end of the insulator; the method is characterized in that: the length of the rod-shaped part of the wiring screw rod extending into the insulator along the axial direction is less than 35mm, a rod-shaped connecting piece is arranged between the front end of the rod-shaped part and the central electrode, the length of the rod-shaped part of the wiring screw rod is reduced by increasing the rod-shaped connecting piece, and the connection between the wiring screw rod and the central electrode is ensured.

Further, the rod-shaped connecting piece is one or more than one section, but the total length of the rod-shaped connecting piece is between 5mm and 30 mm.

Furthermore, the wiring screw has oxidation resistance and bending deformation resistance, and can bear the temperature of at least 850 ℃ without melting or losing the conductive function; the rod-shaped connecting piece is made of metal materials which can bear the temperature of at least 850 ℃ without melting or losing the conductive function.

Furthermore, the material adopted by the rod-shaped connecting piece comprises carbon steel, nonferrous metals and alloy materials; and the rod-shaped connecting piece and the wiring screw rod are made of the same material or made of different materials.

Furthermore, a sealing body for fixing and sealing is arranged at the joint of the rod-shaped connecting piece and the rod-shaped part of the connecting screw rod, and the rod-shaped part of the connecting screw rod is connected and sealed with the rod-shaped connecting piece through the sealing body.

Furthermore, the outer surface of the rod-shaped connecting piece is provided with a reticulate pattern or a thread, the rod-shaped connecting piece is arranged in the insulator, and the rod-shaped connecting piece is fixed between the rod-shaped part of the wiring screw rod and the central electrode.

Furthermore, the surface of the rod-shaped connecting piece is of a cylindrical polished rod structure.

Further, the seal includes a conductive seal or a resistive seal.

Furthermore, the terminal part of the wiring screw rod is of a cup-shaped structure, and the surface layer of the wiring screw rod is subjected to surface anticorrosion treatment; the surface anticorrosion treatment comprises nickel plating and chrome plating, or composite plating of nickel plating and chrome plating.

A method for manufacturing a spark plug comprises the steps of respectively manufacturing each part or part of the spark plug, and then assembling each part into a spark plug whole; the method is characterized in that: the insulator part is formed by respectively manufacturing an insulator, a central electrode, a rod-shaped connecting piece and a wiring screw rod, then pressing the rod-shaped connecting piece, the central electrode, the wiring screw rod and a sealing body into the insulator together, and sintering at high temperature.

Furthermore, when the wiring screw rod is manufactured, the length of the rod-shaped part of the wiring screw rod is controlled to be less than 35mm, and the deformation amount Delta L of the rod-shaped part of the wiring screw rod in the normal direction of AL1 in the press-fitting process is controlled to be 0.06-0.09 mm.

Furthermore, when the rod-shaped connecting piece is manufactured, the length is controlled to be between 5mm and 30mm, and the total length of the combined rod-shaped part of the wiring screw and the rod-shaped connecting piece is controlled to be the length required by the connection between the rod-shaped part of the wiring screw and the central electrode; an extended length is required to maintain the connection of the rod-shaped portion of the terminal screw to the center electrode by adding a rod-shaped connector.

The invention has the advantages that:

the invention limits the rod-shaped part of the screw to be less than 35mm, and extends the length of the rod-shaped part of the wiring screw through the rod-shaped connecting piece, thereby effectively shortening the length of the rod-shaped part of the wiring screw, solving the process difficulty of the wiring screw in production caused by the forced increase of the rod-shaped part due to the prolonged distance between the terminal part and the shell, and being remarkably helpful for improving the strength of the spark plug.

Drawings

FIG. 1 is a schematic structural diagram of one embodiment of the present invention;

FIG. 2 is a schematic view of the amount of deformation Δ L of the stick in the normal direction AL1 during press fitting of the terminal screw;

FIG. 3 is a schematic view of a spark plug impact resistance testing apparatus;

FIG. 4 is a schematic structural diagram of another embodiment of the present invention;

FIG. 5 is a schematic structural diagram of another embodiment of the present invention;

fig. 6 is a schematic structural diagram of another embodiment of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and specific examples.

Example one

The present inventors have found that, due to the strictness of the engine size and emission regulations, the technologies such as turbocharging and in-cylinder direct injection are applied to the engine, the required ignition voltage of the spark plug is increased from 20kv or less to 40kv or less, and as the required ignition voltage is increased, the current leaks from the terminal portion of the terminal screw of the spark plug to the housing, and thus, in recent years, a spark plug with a longer distance from the terminal portion of the terminal screw of the spark plug to the housing has appeared.

Therefore, the invention provides a spark plug with a cup-type wiring terminal, which comprises an insulator 2, a wiring screw rod 1, a central electrode 3, a side electrode 5 and a shell 4; wherein the insulator 2 has a stepped hole in the axial direction; a center electrode 3 at least partially inserted into a front end side of the stepped hole of the insulator 2; the connecting screw rod 1 is provided with a terminal part 1A and a rod-shaped part 1B, the rod-shaped part 1B is inserted into a stepped hole of the insulator 2, the terminal part 1A leaks out of the rear end of the insulator 2, and the terminal part 1A has a cup-shaped characteristic; in order to increase the creepage distance, the rear half of the extended insulator is adopted, namely the distance from the terminal part 1A of the wiring screw rod 1 to the shell 4 is increased; however, in order to ensure the strength of the spark plug and reduce the difficulty in processing and manufacturing the terminal screw 1, the length of the rod-shaped part 1B of the terminal screw 1 extending into the insulator along the axial direction is 35mm or less, and the deformation amount DeltaL of the rod-shaped part 1B of the terminal screw 1 in the normal direction of AL1 during press fitting is controlled to be 0.06-0.09 mm; meanwhile, an elongated insulator structure is adopted, namely, under the condition that the distance from the terminal part 1A of the wiring screw rod 1 to the shell is increased; in order to ensure that the terminal part 1A of the wiring screw 1 can be connected with the central electrode under the condition of increasing the distance from the shell, a rod-shaped connecting piece 6 is arranged between the front end of the rod-shaped part 1B of the wiring screw 1 and the central electrode, the length of the rod-shaped part 1B of the wiring screw 1 is reduced by increasing the rod-shaped connecting piece 6, and the connection between the wiring screw 1 and the central electrode 3 is ensured.

The wiring screw 1 is provided with a terminal part 1A leaking out of the rear end of the insulator 2 and a rod-shaped part 1B inserted into the stepped hole of the insulator; the terminal part 1A of the wiring screw rod 1 is of a cup-shaped structure, the terminal part 1A of the wiring screw rod is provided with a concave part which extends along the front end of the insulator 2 in the depth direction, and the surface layer of the wiring screw rod is treated by zinc plating or cadmium plating; the rod-shaped part 1B of the connecting screw rod 1 is fixed in the insulator 1, and the length of the rod-shaped part 1B extending into the insulator 1 along the axial direction is less than or equal to 35 mm; can be 35mm, 33mm, 31 mm, 29mm, 27 mm and 26 mm, and is determined according to the length of the rear half of the extended insulator part of the insulator 2, and the optimal scheme is controlled to be 29-33 mm.

Table 1 shows the amount of deformation Δ L (fig. 2) of the rod-shaped part 1B in the normal direction AL1 during press-fitting of the terminal screw 1 of different diameters and lengths, which Δ L increases as the diameter D1 of the rod-shaped part 1B of the terminal screw 1 decreases and the length L1 increases.

TABLE 1 distribution of Δ L

Unit: mm is

Table 2 shows the impact resistance of the spark plugs with different Δ L, fig. 3 shows a schematic diagram of the testing equipment for the impact resistance of the spark plugs, the spark plugs are placed on a test bench surface 21 by a special device, a weight 19 (about 160 g) falls freely along a guide rail 20 with scales to impact the rear end of an insulator of the spark plugs, the initial height of the weight 19 is from low to high, namely 10cm, 15cm, 20cm, 25cm, 30cm … … and 100cm respectively, until the rear end of the insulator of the spark plugs cracks, and the initial height of the weight when the weight falls is recorded, and the specific test data are shown in table 2:

TABLE 2 spark plug shock resistance with different DeltaL

Unit: mm is

From the data shown in table 2, it is possible to make the smaller Δ L, the stronger the impact resistance of the insulator of the spark plug, and to significantly contribute to the improvement of the strength of the spark plug by reducing the length of the rod-shaped portion 1B of the terminal screw by increasing the rod-shaped object.

The rod-shaped connecting piece 6 is a section, the length of the rod-shaped connecting piece 6 is between 5mm and 30mm, the rod-shaped connecting piece is selected and matched according to the length of the rod-shaped part 1B of the wiring screw 1, and the total length of the combined rod-shaped part 1B of the wiring screw 1 and the rod-shaped connecting piece 6 is controlled to be the length required by the connection between the rod-shaped part 1B of the wiring screw 1 and the central electrode; an extended length is required to maintain the connection of the rod-shaped portion 1B of the terminal screw to the center electrode by adding a rod-shaped connector. That is, if the length of the rod-shaped connector is set to L, the length of the rod-shaped portion 1B of the terminal screw is set to C, and the thickness of the seal body at the joint of the rod-shaped connector and the rod-shaped portion 1B of the terminal screw is set to D, L plus C plus D is equal to the distance (H) from the port of the insulator to the upper end surface of the resistor.

The wiring screw rod 1 is made of high-quality carbon steel which can bear the temperature of at least 850 ℃ without melting or losing the conductive function, and the wiring screw rod 1 is subjected to anticorrosion treatment so as to have the oxidation resistance and the bending deformation resistance; the rod-shaped connecting piece 6 is made of high-quality low-carbon steel which can bear the temperature of at least 850 ℃ without melting or losing the conductive function, and the surface of the rod-shaped connecting piece 6 is also subjected to anti-corrosion treatment, wherein the anti-corrosion treatment comprises nickel plating or chromium plating treatment, or nickel plating can be carried out firstly, and then chromium plating is carried out on the nickel plating layer; the material of the rod-shaped connecting piece 6 can be the same as that of the wiring screw rod 1 or different from that of the wiring screw rod, but the material of the rod-shaped connecting piece 6 is required not to change the electromagnetic environment when the spark plug works obviously.

An upper sealing body 7 for fixing and sealing is arranged at two end heads of the rod-shaped connecting piece 6, namely at the joint of the rod-shaped connecting piece 6 and the rod-shaped part 1B of the wiring screw rod, and the connection and the sealing of the rod-shaped part of the wiring screw rod and the rod-shaped connecting piece are ensured through the sealing body; a lower sealing body 9 for fixing and sealing is also arranged between the rod-shaped connecting piece 6 and the central electrode 3; an intermediate sealing body 8 for fixing the rod-shaped connecting element 6 can also be arranged between the sealing body 9 and the rod-shaped connecting element 6. When the spark plug is of a resistance type, the upper sealing body 7 is a conductive sealing body, the lower sealing body 9 is a resistor body, the resistor body is of a single layer or three layers, and the structure of the resistor body of the three layers is a structure of conductive glass, resistance glass and conductive glass; if the spark plug is a non-resistance spark plug, the upper sealing body 7 is a conductive sealing body, and the lower sealing body 9 is conductive glass; the intermediate seal 8 may be a conductive seal or a resistive seal.

The rod-shaped connecting piece 6 is cylindrical, and the outer surface of the rod-shaped connecting piece can be a polished rod; it may also be provided with a cross-hatching, a thread, to facilitate its press-fitting into the insulator 2; the rod-shaped connector 6 is press-fitted between the rod-shaped portion 1B of the terminal screw 1 and the center electrode, and is fixed by the upper seal body 7 and the intermediate seal body 8.

The terminal part 1A of the wiring screw 1 is of a cup-shaped structure, and for corrosion prevention, the surface layer of the wiring screw is subjected to nickel plating or chromium plating treatment, or nickel plating is firstly carried out, then chromium plating is carried out on the nickel plating layer, and composite electroplating treatment is carried out.

The manufacturing method of the spark plug insulator component comprises the following steps:

a method for manufacturing a spark plug comprises the steps of respectively manufacturing each part or part of the spark plug, and then assembling each part into a spark plug whole; the insulator component is manufactured by respectively manufacturing an insulator 2, a central electrode 3, a resistor 9, a rod-shaped connecting piece 6, sealing

bodies

7 and 8 and a wiring screw 1; then, the central electrode 3, the resistor body 9, the rod-shaped connecting piece 6, the sealing

bodies

7 and 8 and the wiring screw 1 are sequentially pressed into the insulator 2 according to the central electrode 3, the resistor body 9, the sealing body 8, the rod-shaped connecting piece 6, the sealing body 7 and the wiring screw 1 to form an integral insulator component; the insulator components are then assembled with the housing 4 to form the completed spark plug.

When the wiring screw rod 1 is manufactured, the length of the rod-shaped part of the wiring screw rod is controlled to be less than 35mm, and the deformation delta L of the rod-shaped part of the wiring screw rod in the normal direction of AL1 in the press fitting process is controlled to be 0.06-0.09 mm.

When the rod-shaped connecting piece 6 is manufactured, the length is controlled to be between 5mm and 30mm, and the total length of the combined rod-shaped part of the wiring screw and the rod-shaped connecting piece is controlled to be the length required by the connection of the rod-shaped part of the wiring screw and the central electrode; an extended length is required to maintain the connection of the rod-shaped portion of the terminal screw to the center electrode by adding a rod-shaped connector.

The manufacturing method of the spark plug insulator part comprises the following specific manufacturing steps:

1) firstly, respectively manufacturing each component or part of the spark plug, wherein the insulator, the central electrode, the rod-shaped connecting piece, the sealing body and the wiring screw rod are manufactured on the insulator component; wherein, the length of the rod-shaped part 1B of the terminal screw of the terminal component is controlled below 35mm, and the rod-shaped part 1B of the terminal screw is kept connected with the central electrode by adding a rod-shaped connecting piece; the length of the rod-shaped connecting piece is between 5mm and 30mm, and the total length of the combined rod-shaped part 1B of the wiring screw and the rod-shaped connecting piece is controlled to be the length required by the connection of the rod-shaped part 1B of the wiring screw and the central electrode;

2) pressing the manufactured central electrode, the manufactured rod-shaped connecting piece, the manufactured sealing body and the manufactured wiring screw rod into the insulator in sequence according to the central electrode, the manufactured sealing body, the manufactured rod-shaped connecting piece, the manufactured sealing body and the manufactured wiring screw rod to form an insulator part;

3) heating and sintering the pressed insulator part, so that the rod-shaped connecting piece is fixed between the rod-shaped part 1B of the wiring screw rod and the central electrode by the two sections of sealing bodies;

4) and assembling the sintered insulator component with the shell to form the complete spark plug.

The following table shows the vibration resistance, the wire screw pull-out resistance and the resistance life of the spark plug according to the present invention compared to the conventional spark plug:

TABLE 3 vibration resistance, wire screw pull-out and resistance life conditions

	Vibration resistance	Drawing force of wiring screw	Durability of electrical resistance
				The invention relates to a spark plug	Qualified heat sealing test and voltage resistance test	＞980N	Rate of change of resistance < (R) >30%
Conventional spark plug	Qualified heat sealing test and voltage resistance test	＞980N	The resistance change rate is less than 30 percent

The test methods of the tests listed in the above table are all carried out with reference to the methods specified in the GB/T7825-2017 standard.

The spark plug of the invention can achieve the performance of the traditional spark plug in other performance aspects, and can improve the strength of the rear end part of the insulator of the spark plug.

Example two

The basic principle of the second embodiment is the same as that of the first embodiment, except that the adopted materials and structures are different, as shown in fig. 4, the spark plug is a cup-type wiring terminal spark plug, and comprises an insulator 202, a wiring screw 201, a central electrode 203, a side electrode 205 and a shell 204; wherein the insulator 202 has a stepped hole in the axial direction; the center electrode 203 is at least partially inserted into the front end side of the stepped hole; the connection screw 210 has a terminal part 201A and a rod-shaped part 201B, the rod-shaped part 201B is inserted into the stepped hole of the insulator, the terminal part 201B is leaked out of the rear end of the insulator, and the terminal part 201B has a cup-shaped characteristic; in order to increase the creepage distance, a structure of an extended insulator is adopted, that is, the distance from the terminal part 201B of the wiring screw 201 to the shell 204 is increased; however, in order to ensure the strength of the spark plug and reduce the difficulty in processing and manufacturing the terminal screw, the length of the rod-shaped portion 201B of the terminal screw, which extends into the insulator 202 along the axial direction, is 25-29mm, and the deformation amount DeltaL of the rod-shaped portion 201 in the normal direction of AL1 during press-fitting is controlled to be 0.04-0.06 mm; meanwhile, when the distance from the terminal part of the connection screw 201 to the housing 204 is increased; in order to ensure that the terminal portion 201B of the terminal screw 201 can be connected to the center electrode 203 when the distance from the housing 204 increases, a rod-shaped connecting member 206 is provided between the tip of the rod-shaped portion 201B of the terminal screw 201 and the center electrode 203, and the length of the rod-shaped portion 201B of the terminal screw is reduced by increasing the rod-shaped connecting member 206, thereby ensuring the connection between the terminal screw 201 and the center electrode 203.

The insulator 202 is provided with a center electrode 203, a lower sealing body 209, a rod-shaped connector 206, an upper sealing body 207, and a terminal screw 201 arranged in this order.

The total length of the two rod-shaped connecting pieces is controlled to be between 10mm and 30mm, and the total length of the sealing body is controlled to be the length required by the connection between the rod-shaped part of the wiring screw and the central electrode after the rod-shaped part of the wiring screw and the two rod-shaped connecting pieces are combined.

The wiring screw 201 is made of carbon steel materials which can bear the temperature of at least 850 ℃ without melting or losing functions, and the surface of the wiring screw is plated with nickel or chrome; the rod-shaped connecting member 206 is also made of carbon steel material which can bear at least 850 ℃ without melting or losing functions, and the surface is also subjected to anticorrosion treatment, such as nickel plating or chromium plating.

A sealing body 207 for fixing and sealing is arranged at the joint of the rod-shaped connecting piece 206 and the rod-shaped part of the connecting screw rod; the sealing body at the joint of the rod-shaped connecting piece and the rod-shaped part of the wiring screw rod is a conductive sealing body 207; the lower sealing member 209 at the joint between the rod-shaped connector and the center electrode resistor is a resistor sealing member, but the lower sealing member 209 may be a conductive sealing member if it is a non-resistor type spark plug.

The others are the same as the embodiments.

EXAMPLE III

The basic principle of the third embodiment is the same as that of the first embodiment, except that the adopted materials and structures are different, as shown in fig. 5, the third embodiment is a common terminal spark plug, which comprises an insulator 302, a terminal screw 301, a central electrode 303, a side electrode 305 and a shell 304; wherein the insulator 302 has a stepped hole in the axial direction; the center electrode 303 is at least partially inserted into the tip side of the stepped hole; the terminal screw 301 has a terminal portion 301A and a rod portion 301B, the rod portion 301B is inserted into the stepped hole of the insulator 302, the terminal portion 301A is exposed at the rear end of the insulator 302, the terminal portion 301A is a general cylindrical terminal, and the height of the terminal portion 301A is within 5 mm; in order to increase the creepage distance, an elongated insulator structure is adopted, namely the distance from the terminal part 301A of the wiring screw 301 to the shell 304 is increased; however, in order to ensure the strength of the spark plug and reduce the difficulty in processing and manufacturing the terminal screw, the length of the rod-shaped part 301B of the terminal screw 301 extending into the insulator along the axial direction is 29-33mm, and the deformation amount DeltaL of the rod-shaped part of the terminal screw 301 in the normal direction of AL1 in the press-fitting process is controlled to be 0.06-0.09 mm; meanwhile, when the distance from the terminal portion 301B of the terminal screw to the housing 304 increases; in order to ensure that the terminal portion 301B of the terminal screw can be connected to the center electrode 303 while being increased from the housing 304, a rod-shaped connecting member 306 is provided between the tip of the rod-shaped portion 301B of the terminal screw and the center electrode 303, and the rod-shaped connecting member 306 is increased to reduce the length of the rod-shaped portion 301B of the terminal screw, thereby ensuring the connection between the terminal screw 301 and the center electrode 303.

A center electrode 303, a lower sealing body 309, a rod-shaped connector 306, an upper sealing body 307, and a terminal screw 301 are arranged in this order in the insulator 302.

The wiring screw 301 is provided with a terminal part which is leaked out of the rear end of the insulator and a rod-shaped part which is inserted into the stepped hole of the insulator; the terminal part 301A of the wiring screw is of a platform structure, and the platform height of the terminal part of the wiring screw is within 5 mm; a rod-shaped part 301B of the terminal screw is fixed inside the insulator 302, and the length of the rod-shaped part 302 extending into the insulator 302 along the axial direction is 35mm or less; and may be 35mm, 33mm, 31 mm, 29mm, 27 mm, 26 mm, determined by the length of the rear half of the insulator 302 from which the insulator member is extended.

The rod-shaped connecting piece 306 is a section, the length of the rod-shaped connecting piece is 10mm-30mm, and the sum of the length of the rod-shaped part of the wiring screw and the length of the rod-shaped connecting piece is ensured to be the length required by the connection between the rod-shaped part of the wiring screw and the central electrode. That is, if the length of the rod-shaped connector is set to L, the length of the rod-shaped portion of the terminal screw is set to C, and the thickness of the sealing body is set to D, L plus C plus D is equal to the distance (H) from the end of the insulator to the upper end face of the lower sealing body.

The wiring screw 301 is made of carbon steel which can bear the temperature of at least 850 ℃ without melting or losing functions, the surface is subjected to antiseptic treatment, nickel is plated firstly, and then chromium is plated on the nickel plating layer; the rod-shaped connecting piece 306 is made of copper alloy material, and the surface is not subjected to anti-corrosion treatment.

An upper sealing body 307 for fixing and sealing is arranged at the joint of the rod-shaped connecting piece 306 and the rod-shaped part 301B of the connecting screw rod, and a lower sealing body 309 is arranged in the middle of the connection of the rod-shaped connecting piece 306 and the central electrode 303; the upper sealing body 307 at the joint of the rod-shaped connecting piece and the rod-shaped part of the wiring screw rod is a conductive sealing body; the lower seal 309 between the rod-shaped connecting member and the center electrode 303 is a conductive seal when the spark plug is a non-resistance type spark plug, and the seal 309 may be any of various conductive glass seals.

The rod-shaped connecting piece 306 is cylindrical, the surface of the rod-shaped connecting piece is a polished rod, a reticulate pattern or a thread structure can be rolled, the rod-shaped connecting piece is pressed into the insulator and then wrapped by the insulator to form a fixed structure, and the rod-shaped connecting piece 306 is fixed between the rod-shaped part 301B of the wiring screw rod and the central electrode 303 through two sections of sealing bodies in a press-fitting mode.

The others are the same as the embodiments.

Example four

The basic principle of the fourth embodiment is the same as that of the first embodiment, except that the adopted materials and structures are different, as shown in fig. 6, the fourth embodiment is a common terminal spark plug, which comprises an insulator 402, a terminal screw 401, a central electrode 403, side electrodes 405 and a shell 404; wherein the insulator 402 has a stepped hole in the axial direction; the center electrode 403 is inserted at least partially into the tip side of the stepped hole; the connecting screw 401 is provided with a terminal part 401A and a rod-shaped part 401B, the rod-shaped part 401B is inserted into a stepped hole of the insulator 402, the terminal part 401A leaks out of the rear end of the insulator 402, the terminal part 401A is a common cylindrical terminal, and the height of the terminal part is limited to be less than 5 mm; in order to increase the creepage distance, an elongated insulator structure is adopted, namely the distance from a terminal part 401A of the wiring screw 401 to the shell 404 is increased; however, in order to ensure the strength of the spark plug and reduce the difficulty in processing and manufacturing the terminal screw, the length of the rod-shaped part 401B of the terminal screw 401 extending into the insulator along the axial direction is 25-29mm, and the deformation amount DeltaL of the rod-shaped part 401B of the terminal screw 401 in the normal direction of AL1 during press fitting is controlled to be 0.04-0.06 mm; meanwhile, when the distance from the terminal portion 401B of the connection screw to the housing 404 is increased; in order to ensure that the terminal portion 401B of the terminal screw can be connected to the center electrode 403 while being increased from the case 404, a rod-shaped connecting member 406 is provided between the tip of the rod-shaped portion 401B of the terminal screw and the center electrode 403, and the rod-shaped connecting member 406 is increased to reduce the length of the rod-shaped portion of the terminal screw, thereby ensuring the connection between the terminal screw 401 and the center electrode 403.

The wiring screw 401 is provided with a terminal part leaking out of the rear end of the insulator and a rod-shaped part inserted into the stepped hole of the insulator; the terminal part of the wiring screw 401 is of a platform structure, and the platform height of the terminal part 401A of the wiring screw 401 is within 5 mm; a rod-shaped part 401B of the terminal screw is fixed inside the insulator, and the length of the rod-shaped part 401B extending into the insulator 402 along the axial direction is 35mm or less; and may be 35mm, 33mm, 31 mm, 29mm, 27 mm, 26 mm, as determined by the length of the rear half of the insulator from which the insulator member extends.

The rod-shaped connecting piece 406 is only two sections, namely an upper rod-shaped connecting piece 406A and a lower rod-shaped connecting piece 406B, the total length of the two sections of rod-shaped connecting pieces is controlled to be between 10mm and 30mm, and the sum of the length of the rod-shaped part 401B of the wiring screw and the total length of the rod-shaped connecting piece 406 is ensured to be the length required by the connection between the rod-shaped part 401B of the wiring screw and the central electrode 403. That is, when the length of the rod-shaped connector 406 is set to L, the length of the rod-shaped portion 401B of the terminal screw is set to C, and the thickness of the sealing body 407 is set to D, L plus C plus D is equal to the distance (H) from the insulator port to the upper end face of the lower sealing body.

The wiring screw 401 is made of carbon steel material which can bear the temperature of at least 850 ℃ without melting or losing functions, and the surface is directly subjected to chromium plating treatment; the rod-shaped connecting member 406 is made of a non-ferrous alloy material, and the surface of the rod-shaped connecting member does not need to be subjected to anti-corrosion treatment.

Sealing bodies 407 and 408 for fixing and sealing are arranged at two ends of the rod-shaped connecting piece 406, namely, at the connecting part of the rod-shaped connecting piece 406 and the rod-shaped part 401B of the connecting screw rod, and at the connecting part of the rod-shaped connecting piece 406 and the upper sealing body 409 and the lower sealing body 409 of the central electrode 403; the sealing body at the joint of the rod-shaped connecting piece and the rod-shaped part of the connecting screw rod is a conductive sealing body 407; the seal at the junction of the rod-like connector and the center electrode lower seal is the lower seal 408.

The surface of the rod-shaped connecting piece 406 is provided with a structure with a mesh or thread similar function, the rod-shaped connecting piece 406 is pressed into the insulator 402 by the aid of the structure with the mesh or thread similar function, and the rod-shaped connecting piece is fixed between the rod-shaped part of the wiring screw rod and the central electrode through two sections of sealing bodies in a press fit mode.

The rest is the same as the third embodiment.

The above listed embodiments are only for clear and complete description of the technical solution of the present invention with reference to the accompanying drawings; it should be understood that the embodiments described are only a part of the embodiments of the present invention, and not all embodiments, and the terms such as "upper", "lower", "front", "back", "middle", etc. used in this specification are for clarity of description only, and are not intended to limit the scope of the invention, which can be implemented, and the changes or modifications of the relative relationship thereof are also regarded as the scope of the invention without substantial technical changes. Meanwhile, the structures, the proportions, the sizes, and the like shown in the drawings are only used for matching with the contents disclosed in the specification, so as to be understood and read by those skilled in the art, and are not used for limiting the conditions under which the present invention can be implemented, so that the present invention has no technical essence, and any structural modification, changes in proportion relation, or adjustments of the sizes, can still fall within the range covered by the technical contents disclosed in the present invention without affecting the effects and the achievable purposes of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention has the advantages that:

the invention limits the rod-shaped part of the screw in the determined length range, and extends the length of the rod-shaped part of the wiring screw through the rod-shaped connecting piece to connect the rod-shaped part with the lower sealing body, thereby effectively shortening the length of the rod-shaped part of the wiring screw and solving the process difficulty of the production of the wiring screw caused by the forced increase of the rod-shaped part due to the prolonged distance between the terminal part and the shell. This has some advantages as follows:

1. by the method of reducing the length of the rod-shaped part of the wiring screw rod by adding the rod-shaped connecting piece, the rod-shaped part of the wiring screw rod can be set below 35mm, so that the phenomenon that the wiring screw rod is bent when an insulator component is produced and manufactured can be avoided, the deformation delta L is reduced, the difficulty of the manufacturing and processing process of the wiring screw rod is reduced, and the qualified rate of the manufacturing and processing of the wiring screw rod is improved.

2. By adding the rod-shaped connecting piece with the length of 3-30mm, the strength of the spark plug can be effectively improved, and the improvement of the compression strength of the spark plug is obviously facilitated.

3. The insulating property and the sealing property of the wiring screw rod part can be effectively improved by additionally arranging a layer of sealing body between the wiring screw rod and the rod-shaped connecting piece.

4. The spark plug of the invention can achieve the performance of the traditional spark plug in other performance aspects, and can improve the strength of the rear end part of the insulator of the spark plug.

The drawings illustrate:

1-Wiring screw

1A-terminal part of wiring screw

1B-Bar-shaped part of a terminal screw

2-insulator

3-center electrode

4-shell

5-side electrode

6-rod-shaped connecting piece

7-upper sealing body

8-intermediate seal

9-lower seal

19-heavy object

20-guide rail

21-bench top.

Claims

1. A spark plug comprises an insulator, a wiring screw rod, a central electrode, a side electrode and a shell; wherein the insulator has a stepped hole in an axial direction; a center electrode at least partially inserted into a front end side of the stepped hole; the connecting screw rod is provided with a terminal part and a rod-shaped part, the rod-shaped part is inserted into the stepped hole of the insulator, and the terminal part is exposed at the rear end of the insulator; the method is characterized in that: the length of the rod-shaped part of the wiring screw rod extending into the insulator along the axial direction is less than 35mm, a rod-shaped connecting piece is arranged between the front end of the rod-shaped part and the central electrode, the length of the rod-shaped part of the wiring screw rod is reduced by increasing the rod-shaped connecting piece, and the connection between the wiring screw rod and the central electrode is ensured; the wiring screw is made of a metal material which has oxidation resistance and bending deformation resistance and can bear the temperature of at least 850 ℃ without melting or losing the conductive function; the rod-shaped connecting piece is made of metal materials which can bear the temperature of at least 850 ℃ without melting or losing the conductive function.

2. The spark plug insulator component of claim 1, wherein: the rod-shaped connecting piece is one or more than one section, but the total length of the rod-shaped connecting piece is between 5mm and 30 mm.

3. The spark plug insulator component of claim 1, wherein: the rod-shaped connecting piece is made of carbon steel, nonferrous metal and alloy material; and the rod-shaped connecting piece and the wiring screw rod are made of the same material or made of different materials.

4. The spark plug insulator component of claim 2, wherein: the connection part of the rod-shaped connecting piece and the rod-shaped part of the wiring screw rod is provided with a sealing body for fixing and sealing, and the connection and the sealing of the rod-shaped part of the wiring screw rod and the rod-shaped connecting piece are ensured through the sealing body.

5. The spark plug insulator component of claim 1, wherein: the outer surface of the rod-shaped connecting piece is provided with a reticulate pattern or a thread, the rod-shaped connecting piece is arranged in the insulator, and the rod-shaped connecting piece is fixed between the rod-shaped part of the wiring screw rod and the central electrode.

6. The spark plug insulator component of claim 1, wherein: the surface of the rod-shaped connecting piece is of a cylindrical polished rod structure.

7. The spark plug insulator component of claim 4, wherein: the seal comprises a conductive seal or a resistive seal.

8. The spark plug insulator component of claim 1, wherein: the terminal part of the wiring screw rod is of a cup-shaped structure, and the surface layer of the wiring screw rod is subjected to surface anticorrosion treatment; the surface anticorrosion treatment comprises nickel plating, chromium plating or composite plating of nickel plating and chromium plating.

9. A method of manufacturing a spark plug as claimed in claim 1, wherein each component or part of the spark plug is separately manufactured and then the parts are assembled into a spark plug body; the method is characterized in that: the insulator part is formed by respectively manufacturing an insulator, a central electrode, a rod-shaped connecting piece and a wiring screw rod, then pressing the rod-shaped connecting piece, the central electrode, the wiring screw rod and a sealing body into the insulator together, and sintering at high temperature.

10. The method of making a spark plug insulator component as claimed in claim 9, wherein: when the wiring screw rod is manufactured, the length of the rod-shaped part of the wiring screw rod is controlled to be less than 35mm, and the deformation delta L of the rod-shaped part of the wiring screw rod in the normal direction of AL1 in the press fitting process is controlled to be 0.06-0.09 mm.

11. The method of making a spark plug insulator component as claimed in claim 9, wherein: when the rod-shaped connecting piece is manufactured, the length is controlled to be between 5mm and 30mm, and the total length of the combined rod-shaped part of the wiring screw and the rod-shaped connecting piece is controlled to be the length required by the connection of the rod-shaped part of the wiring screw and the central electrode; an extended length is required to maintain the connection of the rod-shaped portion of the terminal screw to the center electrode by adding a rod-shaped connector.