JP2002070696A - Seal structure for fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal structure between a fuel injection valve retainer for retaining a fuel injection valve such as cylinder head or the like and the fuel injection valve in an internal combustion engine having the fuel injection valve. SOLUTION: In the internal combustion engine comprising the fuel injection valve 4 attachably and detachably mounted on the fuel injection valve retainer 1 for retaining the fuel injection valve of the internal combustion engine, an annular groove 6 is circumferentially formed on the outside surface of the tip part 5 of the fuel injection valve 4 slidably inserted to the fitting hole 2 of the fuel injection valve retainer 1, and an endless resin seal ring 8 having a heat resisting seal oil applied thereto is mounted on the annular groove 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure between a fuel injection valve and a fuel injection valve holder such as a cylinder head for holding the fuel injection valve in an internal combustion engine having the fuel injection valve. .

[0002]

2. Description of the Related Art Conventionally, as a spark ignition type internal combustion engine which is effective in improving exhaust emissions and fuel efficiency by lean combustion, an in-cylinder in which fuel is directly injected into a combustion chamber from a fuel injection valve provided in a cylinder head. Injection type internal combustion engines are known.

In this cylinder injection type internal combustion engine, an annular groove is formed along the circumferential direction on the outer peripheral surface of the tip end of the fuel injection valve inserted into the mounting hole of the fuel injection valve provided in the cylinder head. In some cases, a metal ring member for heat radiation was mounted in the groove (see Japanese Patent Application Laid-Open No. 9-126089).

In the direct injection type internal combustion engine described in Japanese Patent Application Laid-Open No. 9-126098, the heat dissipating metal ring member is formed between the annular groove of the fuel injection valve and the inner peripheral surface of the mounting hole of the fuel injection valve of the cylinder head. In order to make contact, combustion heat applied to the tip of the fuel injection valve is transmitted to the cylinder head via the heat-dissipating metal ring member having excellent thermal conductivity,
The tip of the fuel injection valve is actively cooled, the overheating of the fuel injection valve by the combustion gas is prevented beforehand, the layout of the combustion injection valve can be freely set, the durability is improved, and the cost is reduced. It becomes possible.

[0005]

However, in the above-described in-cylinder injection type internal combustion engine, the gap between the inner peripheral surface of the mounting hole of the fuel injection valve of the cylinder head and the outer peripheral surface of the front end portion of the fuel injection valve is large.
Although closed by a metal ring member, the metal ring member has an abutment (slit) for fitting into an annular groove on the outer peripheral surface of the tip end portion of the fuel injection valve. The impermeability has been imperfect, and it has been difficult to reliably prevent leakage of high-pressure combustion gas.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an improvement in the seal structure of a fuel injection valve which overcomes such difficulties, and the invention as defined in claim 1 holds the fuel injection valve of an internal combustion engine. In an internal combustion engine provided with a fuel injection valve detachably mounted on a fuel injection valve holder, an outer peripheral surface of a distal end portion of the fuel injection valve which is removably inserted into a fitting hole of the fuel injection valve holder. An annular groove is formed in the direction, and a seal ring made of an endless resin coated with heat-resistant seal oil is mounted in the annular groove.

According to the first aspect of the present invention, since the endless seal ring is mounted in the annular groove formed on the outer peripheral surface of the front end portion of the fuel injection valve, the fitting hole of the fuel injection valve holder for holding the fuel injection valve is provided. And the gap between the fuel injection valve and the outer peripheral surface at the tip end is sealed by the endless seal ring.

Since the endless seal ring is made of a resin material and heat-resistant seal oil is applied to the endless seal ring, the inner peripheral surface of the fitting hole of the fuel injection valve holder and the fuel injection valve are not sealed. Sealing with the outer peripheral surface of the tip is further ensured, and leakage of high-pressure combustion gas in the combustion chamber and intrusion of carbon into the gap are prevented beforehand.

In addition, since the heat-resistant seal oil is applied to the outer peripheral surface of the endless seal ring, the endless seal ring is protected by the heat-resistant seal oil, and the endless seal ring comes into contact with a high-pressure and high-temperature combustion gas. Is avoided, and the durability of the endless seal ring is greatly improved.

According to the second aspect of the present invention, the heat-resistant seal oil leaking from the resin endless seal ring coated with the heat-resistant seal oil is stored in the oil storage groove. High sealing effect.

In addition, when the high-pressure and high-temperature combustion gas enters the gap between the inner peripheral surface of the fitting hole of the fuel injection valve holder and the outer peripheral surface of the front end of the fuel injection valve from the combustion chamber, the oil reservoir groove is formed. The high-pressure and high-temperature combustion gas flows into the inside, and the pressure damping function works, thereby preventing the intrusion into the gap and improving the sealing performance.

Further, according to the present invention, the heat-resistant seal oil applied to the endless resin seal ring is sufficiently retained in the circumferential oil reservoir groove of the endless seal ring. Therefore, the sealing effect is further enhanced.

Then, high-pressure and high-temperature combustion gas from the combustion chamber flows into the oil reservoir groove of the endless seal ring, and a pressure attenuating function of the space of the oil reservoir groove causes the inner periphery of the insertion hole of the injection valve holder to be inserted. Intrusion of high-pressure and high-temperature combustion gas into the gap between the surface and the outer peripheral surface of the tip of the fuel injection valve is suppressed,
Sealability is further improved.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; In a spark-ignition direct injection type internal combustion engine, a cylinder head 1 is integrally connected to a cylinder block (not shown) below the cylinder head 1, and a fitting hole of a fuel injection valve body (not shown) is formed in an upper portion of the cylinder head 1. The main body (not shown) of the fuel injection valve 4 is detachably fitted in the fitting hole.

The cylinder head 1 is formed with a fitting hole 2 which is located on an extension of the fitting hole and opens substantially at the center of the combustion chamber 3. It is formed in a cylindrical shape, and has a fitting hole 2 of a cylinder head 1.
The tip 5 of the fuel injection valve 4 is inserted so as to be able to be freely inserted and removed.

Further, an annular seal ring fitting groove 6 having a short cross section directed in the circumferential direction is formed on the outer peripheral surface of the distal end portion 5 of the fuel injection valve 4. An annular oil sump groove 7 is formed on the outer peripheral surface of the fuel injection valve 4 from the groove 6 near the tip end thereof, in parallel with the annular seal ring fitting groove 6, and has an annular width substantially equal to the width of the annular seal ring fitting groove 6. An endless seal ring 8 having a short cross section slightly thicker than the depth of the seal ring fitting groove 6 is fitted in the annular seal ring fitting groove 6.

The endless seal ring 8 is made of an elastic material such as fluororesin such as PTFE.

The heat-resistant seal oil is a silicone-based seal oil having high heat resistance and high viscosity. As shown in FIG. 2, as the oil viscosity indicated by the horizontal axis increases (rightward). Correspondingly, the seal toughness (seal limit pressure) indicated by the vertical axis has a characteristic of increasing (upward) from the proportional relationship.

In the embodiment shown in FIG. 1, the high-viscosity seal oil is applied to the entire outer surface, the inner peripheral surface, or the inner peripheral surface and the upper and lower end surfaces of the endless seal ring 8 because it is configured as described above. When the coating is applied and the endless seal ring 8 is fitted into the annular seal ring fitting groove 6 of the fuel injection valve 4, the elasticity of the annular seal ring fitting groove 6 and the frictional force reducing action of the lubricating oil reduce the fuel injection valve 4. The annular seal ring fitting groove 6 is smoothly and easily fitted into the annular seal ring fitting groove 6.

When the endless sealing 8 is relatively rich in self-lubricating properties, the high-viscosity sealing oil is not applied to the endless sealing ring 8 but is applied to the annular sealing ring fitting groove 6. It may be fitted.

When the seal oil is not applied to the entire outer surface or the outer peripheral surface of the endless seal ring 8, the seal oil is applied to the outer peripheral surface of the endless seal ring 8, and When the seal oil is applied to the outer surface or the outer peripheral surface, the main body (not shown) of the fuel injection valve 4 is fitted into a fitting hole (not shown) of the cylinder head 1 as it is, and the fuel injection valve is When the tip 5 of the cylinder 4 is inserted into the fitting hole 2 of the cylinder head 1 and the fuel injection valve 4 is fixed to the cylinder head 1, the fuel injection valve 4 is integrally mounted on the cylinder head 1.

In the mounting operation of the fuel injection valve 4, since the seal oil exists on the outer peripheral surface of the endless seal ring 8,
Even when the outer diameter of the endless seal ring 8 is slightly larger than the inner diameter of the insertion hole 2, the endless seal ring 8 is smoothly inserted into the insertion hole 2.

Further, when the fuel injection valve 4 is mounted on the cylinder head 1, even if the outer peripheral surface of the endless seal ring 8 is in close contact with the inner peripheral surface of the fitting hole 2 and airtightness is high, the thickness of the endless seal ring 8 is high. The endless seal ring 8 is creeped due to the compressive load in the direction and the thermal load caused by the operation of the internal combustion engine, and a gap is likely to be formed between the outer peripheral surface of the endless seal ring 8 and the inner peripheral surface of the fitting hole 2. Has an endless seal ring 8
The airtightness is maintained for a long period of time due to the presence of the seal oil on the outer peripheral surface of the seal.

Further, the fuel injection valve 4 is provided on the cylinder head 1.
Is attached, even if there is a gap between the outer peripheral surface of the endless seal ring 8 and the inner peripheral surface of the fitting hole 2, as described above,
The sealing oil attached to the outer peripheral surface of the endless seal ring 8 also maintains airtightness for a long period of time.

Furthermore, since the seal oil is rich in heat resistance, the viscosity is maintained at a high level and the confidentiality is maintained.

Further, the annular oil reservoir groove 7 is provided below the endless seal ring 8 fitted in the annular seal ring fitting groove 6.
Is formed, even if the seal oil falls from the annular seal ring fitting groove 6 or the endless seal ring 8, it flows into the annular oil reservoir groove 7, and the seal oil exists in the annular oil reservoir groove 7. Therefore, airtightness is reliably maintained by this seal oil.

The annular oil reservoir groove 7 allows the high-pressure and high-temperature combustion gas from the combustion chamber to flow through the fitting hole 2 of the cylinder head 1.
When the combustion gas enters between the inner peripheral surface of the fuel injection valve and the outer peripheral surface of the end portion of the distal end portion 5 of the fuel injection valve 4, the combustion gas flows into the annular oil reservoir groove 7 and swirls in the annular oil reservoir groove 7. A pressure attenuating function is generated due to movement or turbulence of the flow, so that the infiltration of the combustion gas into the gap between the inner peripheral surface of the fitting hole 2 and the outer peripheral surface of the distal end portion 5 is suppressed, and the sealing performance is improved.

In the embodiment shown in FIG. 1, the annular oil reservoir groove 7 is formed on the outer peripheral surface of the fuel injection valve 4 from the annular seal ring fitting groove 6 to the front end. As one embodiment of the described invention, as shown in FIG. 3, the annular oil reservoir groove 7 is not formed in the tip end portion 5 of the fuel injection valve 4, but is provided near the tip of the outer peripheral surface of the endless seal ring 9. An annular oil sump groove 10 oriented in the direction may be formed. In this embodiment, even if the function of damping the combustion gas pressure in the annular oil sump groove 10 is lower than that of the embodiment of FIG. , The function of holding the seal oil is increased.

In the above-described embodiment, the present invention is applied to a spark ignition type direct injection internal combustion engine. However, fuel is supplied to an intake port formed in a cylinder head or an intake manifold separate from the cylinder head. The present invention is also applicable to a spark ignition type internal combustion engine equipped with an injection valve.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an embodiment of the present application.

FIG. 2 is a characteristic diagram of a seal oil applied to the present invention.

FIG. 3 is a longitudinal sectional view of a main part of another embodiment of the present application.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder head, 2 ... Fitting hole, 3 ... Combustion chamber, 4 ... Fuel injection valve, 5 ... Tip part, 6 ... Annular seal ring fitting groove,
7 ... annular oil sump groove, 8 ... endless seal ring, 9 ... endless seal ring, 10 ... annular oil sump groove.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuo Takeuchi 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3G024 AA04 BA21 DA01 DA03 EA01 FA03 FA08 FA14 GA18 GA29 GA31 HA15 3G066 AA02 AB02 BA36 CC03 CD04 CD17

Claims (3)

[Claims] 1. An internal combustion engine having a fuel injection valve removably mounted on a fuel injection valve holder for holding the fuel injection valve of the internal combustion engine, wherein the fuel injection valve holder is removably fitted into the insertion hole. A fuel injection valve, wherein an annular groove is formed in a circumferential direction of an outer peripheral surface of a front end portion of the fuel injection valve, and a seal ring made of an endless resin coated with heat-resistant seal oil is mounted in the annular groove. Valve seal structure. 2. The fuel injection valve seal structure according to claim 1, wherein an oil sump groove is formed in a circumferential direction of an outer peripheral surface of a tip portion of the fuel injection valve between the annular groove and a tip of the fuel injection valve. A seal structure for a fuel injection valve, wherein a seal is formed. 3. The seal structure for a fuel injection valve according to claim 1, wherein an oil reservoir groove is formed in a circumferential direction of an outer peripheral surface of said endless seal ring.