JPH06257534A - Fuel injection device - Google Patents

Abstract

PURPOSE:To reduce particulates, fume, and hydrocarbon in emission by shortening an injection period remarkably and improving absence of fuel at the end of injection period. CONSTITUTION:A spill port 58 in a barrel 57 of a fuel injection pump is made in a helical form of which helical angle is approximately identical to the angle of an inclined groove 59 in a plunger 54, and an injection tube is formed with a tapered tube.

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 pressurizing fuel with a fuel injection pump,
The present invention relates to a fuel injection device that supplies pressurized fuel to a fuel injection nozzle through an injection pipe and injects the fuel from the injection port.

[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.

[0003]

In order to improve the performance and exhaust gas of a diesel engine, it is desirable to perform high pressure injection. When the fuel is injected at a high pressure from the injection port of the fuel injection nozzle, a good spray is formed, and the mixing with the air is performed better, so that the generation of particulate matter and soot can be suppressed. Therefore, conventionally, it has been attempted to reduce the area of the injection port of the fuel injection nozzle.
Alternatively, the cam lift of the fuel injection pump is increased, and the diameter of the plunger of the fuel injection pump is increased to increase the discharge pressure of the fuel injection pump.
However, when the discharge pressure of the fuel injection pump is increased, there arises a problem in strength, or the weight of the frame of the fuel injection pump is increased, which further raises the cost.

Particularly, in order to reduce the particulate matter and smoke in the exhaust gas, it is important to improve the disconnection of the fuel at the final stage of the fuel injection by the fuel injection nozzle. That is, by improving the spill at the end of injection, it becomes possible to reduce particulate matter and smoke in the exhaust gas. However, according to the fuel injection device using the conventional column-type fuel injection pump, the exhaustion of the fuel at the end of injection is not good, and therefore the exhaust gas particularly contains particulate matter and smoke, which is effective. There was no way to solve it.

The present invention has been made in view of the above problems, and it is preferable that the fuel be cut off at the end of injection.
It is therefore an object of the present invention to provide a fuel injection device that reduces particulate matter and smoke in exhaust gas.

[0006]

According to the present invention, fuel is pressurized by a fuel injection pump, and the pressurized fuel is supplied to a fuel injection nozzle through an injection pipe, and the fuel is injected from the injection port. In the injection device, the spill port of the barrel of the fuel injection pump has a helical shape that substantially matches the inclination angle of the inclined groove of the plunger, and the injection pipe has a large pipe inner diameter on the fuel injection pump side. The present invention relates to a fuel injection device characterized by comprising a tapered pipe whose side is smaller.

[0007]

When the plunger is pushed up by the cam in the barrel of the fuel injection pump, the fuel introduced through the spill port is pressurized by the plunger and sent under pressure through the injection pipe to the fuel injection nozzle. Then, the fuel is injected from the injection port of the fuel injection nozzle.

Since the injection pipe is composed of a tapered pipe on the fuel injection nozzle side, the fuel pressure on the fuel injection nozzle side is higher than that on the fuel injection pump side due to the increased pressure, which results in high pressure injection. Is achieved. Further, since the spill port of the barrel has a helical shape that substantially matches the inclination angle of the inclined groove of the plunger, the fuel is cut off very well at the end of injection.

[0009]

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 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.
The fuel injection pump 2 is provided by the injection pipe 24 formed of a tapered pipe.
5 corresponding pump units 26. The fuel injection pump 25 includes a mechanical governor 27, and the mechanical governor 27 controls the control rack 28.
Is adjusted to adjust the supply amount of fuel injected at one time. The fuel injection pump 25 has a cam shaft 29, and a cam 30 attached to the cam shaft 29 drives 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 protrusion 48 is formed on the side surface side of the nozzle holder 37, and a male screw 49 is formed on the protrusion 48, and a connection nut 50 screwed with the male screw 49.
The injection pipe 24 is connected to the nozzle holder 37.

Next, the structure of each pump unit of the fuel injection pump 25 will be described. As shown in FIGS. 3 and 4, a tappet 55 is attached to the lower end of the plunger 54. The tappet 55 is a compression coil spring 56.
Is pressed downward by the cam 30.
Is pressed against the outer peripheral surface of. The spill port 5 is attached to the barrel 57 in which the plunger 54 is slidably fitted.
8 is formed and the inclined groove 5 is formed on the outer peripheral surface of the plunger 54 so as to substantially face the spill port 58.
9 is formed.

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 coil spring 67 presses the delivery valve 64 toward the valve seat 66.

In particular, as shown in FIG. 5, the fuel injection device according to the present embodiment is characterized in that the injection pipe 24 connecting the casing 65 of the delivery valve 64 of each pump unit 26 of the fuel injection pump 25 and the fuel injection nozzle 20. Is constructed by a tapered tube as shown in FIG. The taper pipe 24 has a larger inner diameter on the fuel injection pump 25 side and a smaller inner diameter on the fuel injection noval 20 side.

Further, as shown in FIG. 6, the spill port 58 formed in the barrel 57 of the fuel injection pump 25 has a helical shape which substantially matches the inclination angle of the inclined groove 59 formed in the plunger 54. There is. With such a shape, the fuel is cut off satisfactorily at the end of injection. FIG. 7 shows a conventional spill port 58 formed of a circular hole as a comparative example.

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

A timer 31 is provided depending on a part of the output of the engine.
When the cam shaft 29 is driven via the cam 3, the cam 3 attached to the cam shaft 29 of the fuel injection pump 25
The outer peripheral surface of 0 pushes up the roller of the tappet 55, which causes the plunger 54 to move upward in the barrel 57. Then, the top surface of the plunger 54 closes the spill port 58 and starts the pressure feeding of the fuel. Plunger 54
When is moved further upward, the inclined groove 59 eventually aligns with the spill port 58, so that the pressure in the space above the plunger 54 passes through the inclined groove 59.
To escape to the side, the fuel pumping ends.

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 changes, and 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.

In the fuel injection device for injecting fuel in this way, the shape of the spill port 58 of the plunger barrel 57 of the fuel injection pump 25 is changed from the circular shape shown in FIG. 7 to the helical shape shown in FIG. In addition, the injection pipe 24 for supplying the fuel to the fuel injection nozzle 20 is a tapered pipe as shown in FIG.

In order to increase the pressure of conventional fuel injection, the nozzle 2
Although there is a tendency to reduce the area of the injection port 35 of 0, if the area of the injection port 35 is reduced in this way, the injection period becomes longer and the end of the fuel injection becomes worse at the latter stage, and particulate matter and smoke are contained in the exhaust gas. Alternatively, there was a problem involving hydrocarbons. In the conventional injection system, the spill port 58 has a circular shape as shown in FIG. 7, and the injection pipe 24 is a straight pipe.

On the other hand, as described above, the spill port 58 is used.
By using a helical tube and using a tapered tube as the injection tube 24, the spilling spill of the injection which cannot be obtained by the helical spill port 58 and the tapered tube 24 alone is improved. It was confirmed that this greatly contributes to the reduction of particulate matter in the exhaust gas, and the smoke and hydrocarbons in the exhaust gas are reduced.

FIGS. 8, 9 and 10 show the pressure of the fuel injection pump, the pressure of the fuel injection nozzle, and the lift of the needle valve of the fuel injection nozzle with respect to the cam angle of the pump 25, respectively. As is clear from FIG. 8, according to the present invention, the pressure of the fuel injection pump tends to be lower than in the conventional case. On the other hand, as shown in FIG. 9, the pressure of the fuel injection nozzle is higher in this case than in the conventional case. This is mainly due to the action of the injection pipe 24 which is a tapered pipe. Further, since the pressure of the fuel applied to the fuel injection nozzle 20 is increased in this way, the lift of the needle valve is accelerated as shown in FIG.

FIG. 11 shows injection timing, pump side pressure and nozzle side pressure with respect to the engine speed, respectively. The pressure on the pump side is lower in this case than in the conventional case. On the other hand, the nozzle side pressure is higher in this case than in the conventional case. Moreover, the injection timing of this case is earlier than that of the conventional case.

12 and 13 respectively show the smoke concentration in the exhaust gas and the hydrocarbon concentration in the exhaust gas with respect to the load of the engine. By combining the helical spill port 58 and the taper pipe 24 as in the present case, the concentration in the exhaust gas with respect to the engine load tends to decrease. Further, as shown in FIG. 13, the concentration of hydrocarbons in the exhaust gas with respect to the engine load also tends to decrease. As is apparent from these graphs, it has been proved that the combination of the helical port 58 and the tapered pipe 24 achieves the exhaust gas improvement.

[0030]

According to the present invention, the spill port of the barrel of the fuel injection pump has a helical shape that substantially matches the inclination angle of the inclined groove of the plunger, and the injection pipe has a large pipe inner diameter on the fuel injection pump side. The nozzle side is composed of a smaller tapered tube. Therefore, by supplying the fuel pressure to the fuel injection nozzle side at a pressure higher than that in the conventional case and making the fuel cut off at the end of injection favorable, the injection period can be greatly shortened. That is, the fuel cutoff at the end of injection is improved, whereby the amount of particulate matter, smoke or hydrocarbons in the exhaust gas can be reduced, and a significant improvement in exhaust gas is achieved.

[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 an 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 vertical sectional view of the fuel injection pump.

FIG. 5 is a cross-sectional view of an injection pipe.

FIG. 6 is a longitudinal sectional view of a main part of a fuel injection pump.

FIG. 7 is a sectional view of a main part of a conventional fuel injection pump.

FIG. 8 is a graph showing a change in pressure of a fuel injection pump with respect to a pump / cam angle.

FIG. 9 is a graph showing a change in pressure of a fuel injection nozzle with respect to a pump / cam angle.

FIG. 10 is a graph showing a change in a fuel injection nozzle needle valve lift with respect to a pump / cam angle.

FIG. 11 is a graph showing changes in injection timing, pump-side pressure, and nozzle-side pressure with respect to engine speed.

FIG. 12 is a graph showing changes in the smoke concentration of exhaust gas with respect to the load of the engine.

FIG. 13 is a graph showing changes in the concentration of hydrocarbons in exhaust gas with respect to the load of the engine.

[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 (Tapered Pipe) 25 Fuel Injection Pump 26 Pump Unit 27 Mechanical Governor 28 Control rack 29 Cam shaft 30 Cam 31 Timer 34 Nozzle 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 screw 47 Cap 48 Projection 49 Male screw 50 Connection nut 51 Fuel sump 54 Plunger 55 Tappet 56 Coil spring 57 Barrel 58 Spill port 59 Inclined groove 60 Pin On 61 the control sleeve 62 the notch 63 engagement plate 64 Deriberibarubu 65 casing 66 valve seat 67 spring

Claims (1)

[Claims] 1. A fuel injection device for pressurizing fuel by a fuel injection pump, supplying the pressurized fuel to a fuel injection nozzle through an injection pipe, and injecting the fuel from the injection port. The barrel spill port has a helical shape that substantially matches the inclination angle of the inclined groove of the plunger, and the injection pipe has a large pipe inner diameter on the fuel injection pump side and a small taper pipe on the fuel injection nozzle side. A fuel injection device characterized by the above.