JPH07103106A - Fuel injection device - Google Patents

Abstract

PURPOSE:To move a nozzle needle rapidly in its close direction and also shorten its injection time by forming a recess in the sliding seal surface of the nozzle needle in a fuel injection nozzle to which fuel pressure is applied intermittently by a fuel injection pump so as to reduce sliding friction. CONSTITUTION:A fuel injection device feeds fuel from a fuel injection pump 25 to a fuel injection nozzle 20. Also the fuel fed to the fuel injection nozzle 20 passes through passages 42 and 43 and applies pressure to a fuel sump 51. As a result, a nozzle needle 38 rises while compressing a spring 40 through a rod 39 to depart from a valve seat 41 and thus fuel is injected from an injection nozzle 35. On the other hand, the nozzle needle 38 stops fuel injection because the conical part 69 at its tip is pressed against the valve seat 41 by the spring 40. In this case, a recess 71 formed in a spiral groove is provided around the circumference of the sliding seal surface 10 of the nozzle needle 38. Thus the frictional area on the sliding seal surface 70 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly to a fuel injection device including a fuel injection pump and a fuel injection nozzle.

[0002]

2. Description of the Related Art In a diesel engine, the intake air is compressed to a high temperature state by moving the piston to the top dead center side, and the fuel is injected from the fuel injection nozzle in synchronization with the piston almost reaching the top dead center. Is injected, and the fuel spray is spontaneously ignited by the heat of intake air to perform combustion. Therefore, the diesel engine is provided with a fuel injection pump, which pressurizes the fuel and supplies it to the fuel injection nozzle through the injection pipe. The fuel is injected from the injection port of the fuel injection nozzle into the cylinder. I am trying to jet it.

When the fuel pressure pressurized by the fuel injection nozzle is supplied to the fuel sump of the fuel injection nozzle, the nozzle needle 1 is moved to the nozzle at the sliding seal surface 3 of the nozzle needle 1 shown in FIGS. Lifting while sliding inside, the conical portion 2 on the tip side is separated from the valve seat, whereby fuel is injected from the injection port of the fuel injection nozzle.

[0004]

In such a conventional fuel injection device using the nozzle needle 1, the sliding sealing surface 3 has a straight shape and constitutes a sealing surface having a wide area. In addition, it took time for the nozzle needle 3 to descend after the injection was completed to completely close the injection port. That is, the vibration of the engine and the frictional resistance of the nozzle needle 1 cause the nozzle needle to take a long time to descend, causing post-dripping after the fuel injection, resulting in a long injection period.

The present invention has been made in view of the above problems, and shortens the injection period by making the movement of the sliding portion of the sliding sealing surface of the nozzle needle with the nozzle smoother. It is therefore an object of the present invention to provide a fuel injection device capable of improving exhaust gas and reducing fuel consumption.

[0006]

The present invention is a fuel injection device comprising a fuel injection pump and a fuel injection nozzle,
When the fuel injection pump intermittently pressurizes and supplies the fuel to the fuel sump of the fuel injection nozzle, the nozzle needle lifts while sliding on the sliding seal surface on the outer peripheral side against the built-in spring. In a fuel injection device in which fuel is injected from an injection port apart from a valve seat, a relief is formed in a sliding seal surface of a nozzle needle of the fuel injection nozzle. is there.

[0007]

The fuel is intermittently pressurized by the fuel injection pump. Such intermittent fuel pressure is supplied to the fuel reservoir of the fuel injection nozzle, and the nozzle needle lifts while sliding on its sliding seal surface against the built-in spring. As a result, the nozzle needle separates from the valve seat and fuel is injected from the injection port. Moreover, since a relief is formed on the sliding seal surface of the nozzle needle,
Friction resistance of the nozzle needle during sliding is reduced, and the movement of the nozzle needle is smooth. Therefore, after the end of the injection, the nozzle needle immediately descends, and the injection is quickly ended.

[0008]

1 shows a main part of a diesel engine equipped with a fuel injection device according to an embodiment of the present invention, in which a cylinder block 10 is provided with a cylinder 11 consisting of a through hole. A piston 12 is slidably arranged in the cylinder 11. The piston 12 is connected to the connecting rod 14 by a piston pin 13.

The upper opening of the cylinder 11 is closed by a cylinder head 15, and the cylinder head 15 has an intake port 16 and an exhaust port 1.
7 and 7 are formed respectively. These intake ports 1
6 and the exhaust port 17 are opened and closed by an intake valve 18 and an exhaust valve 19, respectively. A fuel injection nozzle 20 is attached to the cylinder head 15 so as to inject fuel toward a combustion chamber 21 formed on the top surface of the piston 12.

The fuel injection nozzle 20, as shown in FIG.
It is connected to the corresponding pump unit 26 of the column fuel injection pump 25 by the injection pipe 24. The fuel injection pump 25 includes a mechanical governor 27, and the mechanical governor 27 moves a control rack 28 to
The amount of fuel that is injected each time is adjusted. The fuel injection pump 25 includes a cam shaft 29, and a cam 30 attached to the cam shaft 29.
Drive each pump unit 26.
A timer 31 is provided on the camshaft 29, and the timing of injection is adjusted by the timer 31.

The fuel injection nozzle 20, as shown in FIG.
The tip portion is composed of the nozzle body 34, and 4 to 10 injection holes 35 are formed at the tip portion of the nozzle body 34. The nozzle body 34 is attached to the nozzle holder 37 by a retainer 36. A nozzle needle 38 is slidably held in the nozzle body 34. The upper end of the nozzle needle 38 is connected to the compression coil spring 4 in the nozzle holder 37 via the pressing rod 39.
It is designed to be pressed downward by 0. As a result, the nozzle needle 38 is pressure-bonded to the valve seat 41 formed on the nozzle body 34 to shut off the fuel. Further, the nozzle holder 37 is formed with a fuel passage 42 communicating with the injection pipe 24. The fuel passage 42 communicates with the fuel passage 43 of the nozzle body 34. A fuel sump 51 is formed at the end of the fuel passage 43.

The upper end of the spring 40 pressing the pressing rod 39 is received by the spring receiver 44. An adjusting screw 45 is attached to the upper end of the spring receiver 44. The adjusting screw 45 is screwed with a female screw 46 formed on the inner peripheral surface of the nozzle holder 37. Further, a pair of protrusions 48 is formed on the side surface side of the nozzle holder 37, male screws 49 are formed on these protrusions 48, and the injection pipe 24 is formed by a connecting nut 50 screwed with these male screws 49. Nozzle holder 37
It is designed to be connected to.

Next, the structure of each pump unit 26 of the fuel injection pump 25 will be described. As shown in FIG. 3, a tappet 55 is attached to the lower end of the plunger 54. The tappet 55 is pressed downward by the compression coil spring 56, and thereby pressed against the outer peripheral surface of the cam 30. A spill port 58 is formed in the barrel 57 in which the plunger 54 is slidably fitted, and an inclined groove 59 is formed in the outer peripheral surface of the plunger 54 so as to substantially face the spill port 58. ing.

A pinion 60 is rotatably supported on the outer peripheral side of the barrel 57. A control sleeve 61 is fixed to the pinion 60 and a notch 62 formed in the control sleeve 61.
Receives the engagement plate 63. The engagement plate 63 is fixed to the plunger 54.

A delivery valve 64 is provided on the outlet side of each pump unit 26, and is arranged on a valve seat 66 provided at the bottom of the casing 65.
The delivery valve 64 is pressed toward the valve seat 66 by the coil spring 67.

Next, an outline of the operation of the fuel injection device having the above structure will be described.

The timer 31 is controlled by a part of the output of the engine.
When the cam shaft 29 of the column fuel injection pump 25 is driven via the cam, the cam 30 pushes up the roller of the tappet 55, which causes the plunger 54 to move upward in the barrel 57. Then, the peripheral surface of the plunger 54 closes the spill port 58 and starts the pressure feeding of the fuel. When the plunger 54 moves further upward, the inclined groove 59 eventually aligns with the spill port 58, whereby the pressure in the space above the plunger 54 escapes to the spill port 58 side through the inclined groove 59, and the fuel is pumped. finish.

Mechanical governor 2 of fuel injection pump 25
When the 7 moves the control rack 28, the pinion 60 is rotated, which causes the control sleeve 6 to move.
1 will be rotated. The rotation of the control sleeve 61 is transmitted to the plunger 54 via the notch 62 and the engaging plate 63, and the plunger 54 is rotated in the barrel 57. Therefore spill port 5
8, the effective stroke determined by the position of the inclined groove 59 aligned with 8 is changed, the fuel is metered,
The supply amount of fuel injected at one time is controlled. The timer 31 provided on the camshaft 29 of the fuel injection pump 25 controls the phase angle of the camshaft 29 and adjusts the fuel injection timing.

When the plunger 54 pumps the fuel in the barrel 57, the delivery valve 64 is opened and the fuel is pumped to the fuel injection nozzle 20 through the injection pipe 24. The fuel passage 4 of the fuel injection nozzle 20 shown in FIG.
When fuel pressure is applied to the fuel sump 51 through 2 and 43, the nozzle needle 38 moves through the rod 39 into the spring 4
0 is compressed and moves upward, whereby the tip end side portion of the nozzle needle 38 separates from the valve seat 41, and fuel is injected through the injection port 35. When the pressure feed of the fuel is completed, the elastic restoring force of the spring 40 pushes the nozzle needle 38 downward via the rod 39, and the tip end thereof is pressed against the valve seat 41 to stop the fuel injection.

The fuel is sprayed by the injection port 3 of the fuel injection nozzle 20.
5, the fuel is injected toward the combustion chamber 21 formed on the top surface of the piston 12 shown in FIG. Then, this fuel spray is spontaneously ignited by the heat of the compressed intake air, combustion occurs in the cylinder 11, the piston 12 is pushed downward, and the output of the engine is taken out.
After this, the exhaust valve 19 is opened, and exhaust gas is discharged through the exhaust port 17.

The nozzle needle 38 of the fuel injection nozzle 20 of the fuel injection device for injecting fuel in this way is as shown in FIGS. 4 and 5. That is, the nozzle needle 38 has a conical portion 69 on its tip side,
The conical portion 69 is attached to the valve seat 41 by the spring 40.
The fuel injection is stopped by being crimped to. Moreover, a relief 71 composed of a spiral groove is formed on the outer peripheral portion of the sliding seal surface 70 of the nozzle needle 38.

Thus, in order to reduce the friction area of the sliding seal surface 70 of the nozzle needle 38, the spiral groove 7 is formed.
By forming 1, the nozzle needle 38 that moves up and down is easy and the nozzle needle 38
Can be stably rotated. By using such a nozzle needle 38, it is quickly lowered after the end of injection, the conical portion 69 on the tip side of the nozzle needle 38 is crimped to the valve seat 41, and the injection port 35 is closed. FIG. 6 shows the pressure in the injection pipe 24 on the nozzle side and the lift of the nozzle needle 38 when such a nozzle needle 38 is used, which makes it possible to eliminate the movement of the nozzle 38 and perform better combustion. . The characteristic indicated by the dotted line in FIG.
5 and a characteristic of a fuel injection device using a conventional nozzle needle 1 having a straight sliding seal surface 3 as shown in FIG.

As described above, by using the nozzle needle 38 according to the present embodiment, the movement of the nozzle needle 38 becomes smooth, and the time required for sliding is shortened. In particular, the period required to lower the nozzle needle 38 after the fuel pressure has stopped is shortened, and the pressure in the injection pipe 24 also drops faster from the peak point. Therefore, the injection time is shortened, the combustion is improved, the particulate matter in the exhaust gas is significantly reduced, and the fuel consumption is reduced.

Next, a second embodiment will be described with reference to FIGS. In this embodiment, a plurality of, for example, 5 Vs are provided on the sliding seal surface 70 of the nozzle needle 38 at a predetermined pitch.
The groove 71 is cut so that the nozzle needle 38 can be smoothly moved up and down. Such V groove 71
Can be easily formed by machining, and provides an advantage that the processing method is easy.

By using the nozzle needle 38 in which a plurality of V grooves 71 are formed in this manner, a natural movement is performed when the fuel pressure rises and then descends, and this is promptly performed after the end of injection. The conical portion 69 on the tip end side of the nozzle needle 38 is crimped to the valve seat 41 and the injection port 35 is closed, so that the injection period can be shortened and more efficient fuel injection can be performed. Therefore, according to this embodiment as well, it is possible to obtain the same effects as the first embodiment.

Next, a third embodiment will be described with reference to FIGS. 9 and 10. In this embodiment, a concave concave portion 71 is formed on the sliding seal surface 70 of the nozzle needle 38, and only the upper and lower portions of the concave portion 71 are used as the sliding seal surface 70. Even with such a configuration, it is possible to reduce the frictional resistance of the nozzle needle 38, so that the nozzle needle 38 quickly descends after the end of injection, and the conical portion 6 on the tip side.
The injection period can be shortened by pressing 9 onto the valve seat 41. Therefore, it is possible to efficiently perform the injection, and it is possible to obtain the same effects as those of the first embodiment.

Next, a fourth embodiment will be described with reference to FIGS. 11 and 12. In this embodiment, a relief 71 is formed on the outer peripheral surface of the sliding seal surface 70 of the nozzle needle 38, and the relief 71 is formed into a conical shape to reduce frictional resistance. In this case, the sliding seal surface 70 is formed on the upper end side. With such a configuration, the portion supporting the nozzle needle 38 is not a surface but a shape close to a line, and the frictional resistance becomes smaller. Therefore, the nozzle needle 38 is rapidly lowered at the end of injection, the injection period is shortened, and more efficient fuel injection is performed. Therefore, also in this embodiment, it is possible to obtain the same effects as those of the first embodiment.

Next, a fifth embodiment will be described with reference to FIGS. 13 and 14. In the fifth embodiment, the nozzle needle 38
The sliding seal surface 70 is left only on the lower end side, and a relief 71 is provided on the upper side to form a guide portion having a flower-shaped cross section. The advantage of such a shape is that since the nozzle needle 38 is supported by the linear contact surface on the outer peripheral side of the flower-shaped relief 71, friction is further reduced and the nozzle needle 38 slides smoothly. Will be possible. Therefore, the lowering operation of the nozzle needle 38 can be rapidly performed particularly at the end of injection, and better combustion can be achieved by shortening the injection period. Therefore, also in the fifth embodiment, it is possible to obtain the same effects as those of the first embodiment.

[0029]

As described above, according to the present invention, a relief is formed on the sliding seal surface of the nozzle needle of the fuel injection nozzle to which the fuel pressure is intermittently applied by the fuel injection pump of the fuel injection device. is there.

By forming such an escape,
Friction during the sliding movement of the nozzle needle is reduced, and the sliding movement of the nozzle needle is smoothly performed. In particular, as the injection ends, the nozzle needle moves quickly in the direction to close the valve seat, and the injection period is shortened to achieve better combustion. This makes it possible to reduce the particulates in the exhaust gas and improve fuel efficiency.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a diesel engine including a fuel injection device according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of a fuel injection nozzle.

FIG. 3 is a perspective view of a main part of a fuel injection pump.

FIG. 4 is a plan view of a nozzle needle of a fuel injection nozzle.

FIG. 5 is a front view of a nozzle needle. .

FIG. 6 is a graph showing the nozzle pressure inside the nozzle and the lift of the nozzle needle with respect to the cam angle of the fuel injection pump.

FIG. 7 is a plan view of a nozzle needle according to a second embodiment.

FIG. 8 is a front view of a nozzle needle.

FIG. 9 is a plan view of a nozzle needle according to a third embodiment.

FIG. 10 is a front view of a nozzle needle.

FIG. 11 is a plan view of a nozzle needle according to a fourth embodiment.

FIG. 12 is a front view of a nozzle needle.

FIG. 13 is a plan view of a nozzle needle according to a fifth embodiment.

FIG. 14 is a front view of a nozzle needle.

FIG. 15 is a plan view of a conventional nozzle needle.

FIG. 16 is a front view of a nozzle needle.

[Explanation of symbols]

 10 Cylinder Block 11 Cylinder 12 Piston 13 Piston Pin 14 Connecting Rod 15 Cylinder Head 16 Intake Port 17 Exhaust Port 18 Intake Valve 19 Exhaust Valve 20 Fuel Injection Nozzle 21 Combustion Chamber 24 Injection Pipe 25 Fuel Injection Pump 26 Pump Unit 27 Mechanical Governor 28 Control Rack 29 Cam Shaft 30 Cam 31 Timer 34 Nozzle Main Body 35 Nozzle 36 Retainer 37 Nozzle Holder 38 Nozzle Needle 39 Push Rod 40 Spring 41 Valve Seat 42, 43 Fuel Passage 44 Spring Bearing 45 Adjusting Screw 46 Female Thread 47 Cap 48 Projection 49 Male Thread 50 Connection Nut 51 Fuel sump 52 One-way valve 54 Plunger 55 Tappet 56 Coil spring 57 Barrel 58 Spill port 59 Sloping groove 60 Anions 61 the control sleeve 62 the notch 63 engagement plate 64 Deriberibarubu 65 casing 66 valve seat 67 coil spring 69 yen pyramidal portion 70 sliding seal surface 71 escape

Claims (1)

[Claims] 1. A fuel injection device comprising a fuel injection pump and a fuel injection nozzle, which is built in when the fuel injection pump intermittently pressurizes fuel and supplies it to a fuel reservoir of the fuel injection nozzle. In a fuel injection device in which a nozzle needle lifts while sliding on a sliding seal surface on an outer peripheral side thereof against a spring and is separated from a valve seat and fuel is injected from an injection port, the nozzle needle of the fuel injection nozzle is A fuel injection device characterized in that a relief is formed on a sliding seal surface.