JP2002317730A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device capable of being easily processed to prevent the leakage of high-pressure fuel from a part between passage members with a simple constitution. SOLUTION: This fuel injection device is provided with a fuel injection pump 10, a common rail 70, an injector 71 and the fuel piping. A connection member 60 is connected to a cylinder head 12 by a screw, and connected to the common rail 70 by the fuel piping. The fuel pressurized by the fuel injection pump 10 is supplied to the common rail 70 from the connection member 60, and the high-pressure fuel of a constant pressure is supplied from the common rail 70. An annular projecting part is formed at an opposite face side facing to the connection member 60 of the cylinder head 12 in a state of surrounding a fuel discharge passage 102. As the hardness of the cylinder head 12 is higher than that of the connection member 60, the annular projecting part of the cylinder head 12 bites into the connection member 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a seal structure of a fuel injection device from a fuel injection pump to an injector.

[0002]

2. Description of the Related Art For example, in a high-pressure fuel pump used in a fuel injection device of a diesel engine, a seal member such as a gasket is used to form a high-pressure fuel passage and prevent fuel from leaking from between passage members facing each other. Have been.

[0003]

However, with the tightening of exhaust gas regulations for diesel engines, it has been required to reduce the amount of unburned components in exhaust gas by increasing the pressure of the fuel and atomizing the fuel for injection. I have. Since the fuel pressure is increased to 160 MPa or more due to the demand for increasing the fuel pressure, the gasket may be damaged by the fuel pressure. However, in order to seal the high-pressure fuel by contact between the metal surfaces of the passage members without using a seal member such as a gasket, it is necessary to grind the metal surfaces and make the seal surface smooth. In order to smooth the metal surface so that the high-pressure fuel does not leak, a long working time is required, and there is a problem that the manufacturing cost increases. SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device that can be easily processed to prevent high-pressure fuel from leaking from between passage members with a simple configuration.

[0004]

According to the first aspect of the present invention, the first passage member and the second passage member which form a high-pressure fuel passage and abut against each other to seal the high-pressure fuel. At least one has an annular projection projecting toward the other-side passage member and surrounding the high-pressure fuel passage.

When the passage member having the annular projection is pressed against the other passage member, the annular projection bites into the other passage member or the annular projection is elastically deformed, thereby causing high-pressure fuel. The periphery of the passage is tightly sealed. Since the annular protrusion bites into the other passage member or the annular protrusion elastically deforms, it is not necessary to grind the opposing surfaces of the passage members facing each other smoothly. Therefore, it is easy to process the opposing surfaces of the passage members including the annular protrusion.

According to the fuel injection device of the second aspect of the present invention, since the higher hardness of the pair of passage members has the annular protrusion, the annular protrusion bites into the lower hardness passage member. Cheap. Therefore, the high-pressure fuel can be reliably sealed by the annular projection and the partner passage member. According to the fuel injection device of the third aspect of the present invention, the annular projection is a cutting mark of the end mill formed by cutting the opposing surface of one of the passage members facing the other passage member. Since a plurality of annular projections are formed on concentric circles, the sealing locations of the annular projection and the counterpart passage member are multiplexed. Therefore, the fuel can be reliably sealed.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 1 shows a fuel injection device for a diesel engine according to a first embodiment of the present invention. The fuel injection device includes a fuel injection pump 10, a common rail 70, an injector 71, and a fuel pipe.

As shown in FIG. 1, the pump housing of the fuel injection pump 10 has a housing main body 11 and cylinder heads 12 and 13. The housing body 11 is made of aluminum. The cylinder heads 12, 13 are made of iron,
A plunger 20 as a movable member is supported to be reciprocally movable. A fuel pressurizing chamber 100 is formed by the inner peripheral surfaces of the cylinder heads 12 and 13, the end surface of the check valve 40, and the end surface of the plunger 20.

The drive shaft 14 is rotatably supported by the housing body 11 via a journal 15. The space between the housing body 11 and the drive shaft 14 is sealed by an oil seal 16. The cam 17 having a circular cross section is
And are integrally formed eccentrically. The plunger 20 is disposed 180 on the opposite side of the drive shaft 14.
The shoe 18 has a quadrangular outer shape, and a bush 19 is interposed between the shoe 18 and the cam 17 so as to be slidable with the shoe 18 and the cam 17. Plunger 20
The outer peripheral surface of the shoe 18 and the end surface of the plunger 20 facing each other are formed in a planar shape and are in contact with each other.

The plunger 20 is reciprocally driven by the cam 17 via the shoe 18 as the drive shaft 14 rotates.
From the fuel inflow passage 101 through the check valve 40, the fuel pressurizing chamber 1
At 00, pressurize the sucked fuel. The check valve 40 prevents fuel from flowing back from the fuel pressurizing chamber 100 to the fuel inflow passage 101. The spring 22 urges the plunger 20 toward the shoe 18. As the cam 17 rotates, the shoe 18 revolves without rotating while sliding on the cam 17. The inner gear type feed pump 30 pressurizes the fuel sucked from a fuel tank (not shown) and pressurizes the fuel inflow passage 10.
Send to 1.

As shown in FIG. 2, the check valve 40 has a valve member 41, a spring 42, and a valve body 45. The valve member 41 can be seated on a valve seat 46 formed on a valve body 45. The spring 42 urges the valve member 41 toward the valve seat 46. A fuel inflow passage 101 is formed in the valve body 45. When the valve member 41 is the valve seat 46
When seated, the fuel pressurizing chamber 100 and the fuel inflow passage 101
Communication with is interrupted. The sealing plug 47 seals the valve body 45 from the fuel pressurizing chamber side.

The check valve 50 has a ball 51, a spring 52, and a valve seat 53 on which the ball 51 can be seated. The valve seat 53 is formed on the cylinder head 12 as a passage member. The spring 52 has one end in contact with the spring seat 61 and the other end in contact with the ball 51. The spring 52 urges the ball 51 toward the valve seat 53. The check valve 50 is connected to a fuel pressurizing chamber 100 from a fuel chamber 103 located between a fuel discharge passage 102 formed in a connecting member 60 forming a pair of passage members with the cylinder head 12 and a valve seat 53. Prevent backflow of fuel.
The fuel passage 104 formed in the cylinder head 12 is connected to the fuel discharge passage 102 on the cylinder head 13 side by a fuel pipe (not shown). Cylinder head 1
The fuels pressurized in 2 and 13 respectively join in the fuel chamber 103.

The connecting member 60 is screwed to the cylinder head 12 and connected to the common rail 70 by a fuel pipe. A spring seat 61 is screw-connected to the fuel chamber 103 side of the connection member 60. The fuel pressurized by the fuel injection pump 10 is supplied from the connection member 60 to the common rail 70. The common rail 70 accumulates fuel having a pressure fluctuation supplied from the fuel injection pump 10 and maintains the fuel at a constant pressure. A high-pressure fuel of a constant pressure is supplied to the injector 71 from the common rail 70. The fuel pressurizing chamber 100, the fuel chamber 103, the fuel discharge passage 102 of the cylinder heads 12, 13,
The fuel passage in the fuel pipe connecting the connecting member 60 and the common rail 70, the pressure accumulating chamber in the common rail 70, the fuel passage in the fuel pipe connecting the common rail 70 and the injector 71, and the fuel passage in the injector 71 It constitutes a passage.

Next, the sealing structure between the cylinder head 12 and the connecting member 60 will be described. As shown in FIGS. 3 and 4, an annular projection 121 is formed on the side of the cylinder head 12 facing the connection member 60 so as to surround the fuel discharge passage 102. 3 and 4, the spring seat 61 is omitted. Since the hardness of the cylinder head 12 is higher than the hardness of the connecting member 60, the annular protrusion 12
1 is biting into the connecting member 60. Annular protrusion 121
Are formed by cutting, laser machining, electric discharge machining, electrolytic machining, or the like.

Next, the operation of the fuel injection device will be described. The cam 17 rotates with the rotation of the drive shaft 14, and the cam 1
With the rotation of 7, the shoe 18 revolves without rotating. As the shoe 18 revolves, the flat contact surfaces formed on the shoe 18 and the plunger 20 slide, whereby the plunger 20 reciprocates.

When the plunger 20 at the top dead center is lowered with the revolution of the shoe 18, the fuel discharged from the feed pump 30 flows into the fuel pressurizing chamber 100 from the fuel inflow passage 101 through the check valve 40. When the plunger 20 that has reached the bottom dead center rises again toward the top dead center, the check valve 40 closes, and the fuel pressure in the fuel pressurizing chamber 100 increases. When the fuel pressure in the fuel pressurizing chamber 100 becomes equal to or higher than a predetermined pressure, the ball 51 is separated from the valve seat 53 and the check valve 50 is opened.

The fuel pressurizing chamber 100 on the cylinder head 12 side
The fuel pressurized in the above is sent to the common rail 70 through the check valve 50, the fuel chamber 103, and the fuel discharge passage 102.
The fuel pressurized in the fuel pressurizing chamber 100 on the cylinder head 13 side passes through a fuel pipe (not shown) and passes through the cylinder head 1.
2 fuel passage 104, fuel chamber 103, fuel discharge passage 10
2 and is sent to the common rail 70. The fuel pressurized in both fuel pressurizing chambers 100 joins in the fuel chamber 103 and is supplied from the fuel discharge passage 102 to the common rail 70.

In the first embodiment, since the hardness of the cylinder head 12 is higher than that of the connecting member 60 and the annular protrusion 121 of the cylinder head 12 bites into the connection member 60, the fuel is formed by the annular protrusion 121 and the connection member 60. High-pressure fuel passing from the chamber 103 through the fuel discharge passage 102 can be reliably sealed.

(Second Embodiment) FIG. 5 shows a seal structure between a cylinder head 12 and a connecting member 60 according to a second embodiment of the present invention. In FIG. 5, the spring seat 61 is omitted.
End mill 200 having a cutting blade on the bottom surface (FIGS. 6 and 7)
When the opposing surface 120 of the cylinder head 12 is cut using the cutting tool
A plurality of annular protrusions 130 are formed on the concentric circles as cutting traces at 20.

In the cutting process in which the end mill 200 is pressed against the facing surface 120 of the cylinder head 12, the discharge of the chips may be hindered, and the chips may damage the facing surface 120 as the cutting surface. If the opposing surface 120 is damaged, fuel may leak from the damaged portion. Therefore, FIG.
As shown in (1), it is desirable to form a groove 201 on the bottom surface of the end mill 200 for cutting the chips and discharging the chips. In the second embodiment, a plurality of annular projections 13 are arranged on a concentric circle.
0 is formed, the cylinder head 12 and the connecting member 6
High pressure fuel can be more reliably sealed between 0 and 0.

In the above-described plurality of embodiments showing the embodiment of the present invention, the annular projection surrounding the fuel discharge passage 102 which is a high-pressure fuel passage is provided on the side of the facing surface 120 of the cylinder head 12 facing the connecting member 60. It is formed, and the annular protrusion bites into the connecting member 60. Therefore, high-pressure fuel can be sealed with a simple configuration. Further, since the seal member is not sandwiched between the cylinder head 12 and the connection member 60, the number of parts is reduced and the assembly is easy. Further, since the high pressure fuel is sealed without grinding the opposing surfaces of the cylinder head 12 and the connecting member 60 facing each other, the processing is easy.

In the above embodiments, the fuel injection pump 10
The seal location between the cylinder head 12 and the connection member 60 has been described. In addition to the sealing portion, in the high-pressure fuel passage of the fuel injection device from the fuel injection pump 10 to the injector 71, by forming an annular protrusion on at least one of the opposing surfaces of the passage members forming the high-pressure fuel passage, High pressure fuel can be reliably sealed with a simple configuration. The hardness of the passage members may be different or substantially the same. In addition, the annular protrusion is elastically deformed by being pressed against the passage member on the other side, so that high-pressure fuel can be sealed between the annular protrusion and the passage member on the other side.

In the above embodiments, the cylinder head 1
Although the annular projection is formed only on the two sides, the annular projection may be formed only on the connection member 60 side, or the annular projection may be formed on both the cylinder head 12 and the connection member 60.
Although the sealing surface is a flat surface, it may be a tapered surface.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a fuel injection device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a portion taken along line II of FIG.

FIG. 3 is a cross-sectional view showing a seal structure between a cylinder head and a connection member.

FIG. 4 is a view in the direction of arrow IV in FIG. 3;

FIG. 5 is a sectional view showing a seal structure between a cylinder head and a connection member according to a second embodiment of the present invention.

FIG. 6 is a schematic explanatory view showing a cutting tool according to a second embodiment.

7 is a view taken in the direction of the arrow VII in FIG. 6;

[Explanation of symbols]

 Reference Signs List 10 fuel injection pump (fuel injection device) 12 cylinder head (passage member) 60 connection member (passage member) 70 common rail (fuel injection device) 71 injector (fuel injection device) 100 fuel pressurizing chamber (high-pressure fuel passage) 102 fuel discharge Passage (high-pressure fuel passage) 103 Fuel chamber (high-pressure fuel passage) 120 Opposite surface 121, 130 Annular protrusion 200 End mill

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G066 AA07 AB02 AC05 AC09 AD02 BA35 BA36 BA48 BA61 CA34 CB05 CB09 CC69 CD04 CD10

Claims (3)

[Claims] In a fuel injection device from a fuel injection pump that pressurizes and feeds a fuel to an injector that injects the fuel, a pair of passage members that form a high-pressure fuel passage and abut against each other to seal the high-pressure fuel are formed. A fuel injection device, wherein at least one of the pair of passage members has an annular projection projecting toward a partner passage member and surrounding the high-pressure fuel passage. 2. The passage member having a higher hardness among the pair of passage members has the annular protrusion.
The fuel injection device according to claim 1. 3. The fuel injection device according to claim 1, wherein the annular protrusion is a cutting mark of an end mill formed by cutting an opposing surface facing a counterpart passage member.