JP2599837B2 - Fuel injection rate control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling an injection rate of fuel injected into an engine.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection device, fuel in a fuel tank is fed to a fuel injection pump by a feed pump, and high-pressure fuel sent from the fuel injection pump to a fuel injection nozzle via an injection pipe is injected into an engine through an injection hole. Injection into a cylinder is known. In this device, a timer for changing the injection timing according to the rotation speed of the engine is provided in the injection pump.

[0003]

However, the above-mentioned timer alone cannot control the initial injection rate, so that the fuel injection amount during the ignition delay period is large, and the ignition is performed at once, so that the emission of nitrogen oxides from the engine increases. There was a defect.

[0004] It is an object of the present invention to provide a fuel injection rate control device capable of reducing the emission of nitrogen oxides from an engine.

[0005]

A configuration of the present invention for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. The fuel injection rate control device of the present invention includes an injection pipe 19 for pumping fuel from a fuel injection pump to a fuel injection nozzle 13.
A leakage pipe 21 for returning the fuel overflowing from the injection nozzle 13 to the fuel tank; a bypass pipe 22 having one end branched from the injection pipe 19 and the other end joined to the leakage pipe 21 to be connected; , A valve 23 capable of opening and closing the bypass pipe 22, a top dead center sensor 24 for detecting the position of the top dead center of the piston of the engine, a rotation sensor 26 for detecting the rotation speed of the engine, and a load for the engine. Load sensor 27 and top dead center sensor 2
4, a controller 28 for controlling the valve 23 based on the detection signals of the rotation sensor 26 and the load sensor 27.

[0006]

The controller 28 turns on the valve 23 in the early stage of the injection to open the bypass pipe 22 and communicates the injection pipe 19 with the leakage pipe 21 so that a part of the fuel pumped from the fuel injection pump to the fuel injection nozzle 13 is removed. Leakage tube 2
The fuel is released to the fuel tank from 1 and the injection amount at the beginning of injection is kept low.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; As shown in FIGS. 1 and 2, a fuel injection device that injects fuel into an engine includes a feed pump 11, a fuel injection pump 12, and a fuel injection nozzle 13. An inlet 11 a of the feed pump 11 is connected to a fuel tank 15 via a pipe 14, and an outlet 11 a of the feed pump 11
b is connected to the suction port 12a of the injection pump 12 via the pipe 16, the filter 17, and the pipe 18. Injection pump 1
The second discharge port 12b is connected to the fuel inlet 13a of the fuel injection nozzle 13 via the injection pipe 19, and the top of the injection nozzle 13 is connected to the fuel tank 15 via the leakage pipe 21 (FIG. 2). In this example, a parallel pipe having a constant inner diameter is used as the injection pipe 19 (FIG. 1). A bypass pipe 2 having one end branched from the injection pipe 19 and the other end joining the leakage pipe 21
2 is connected bypassing the injection nozzle 13 and the bypass pipe 2
A valve 23 is provided in the middle of 2. This valve 23
Is an electromagnetic valve capable of opening and closing the bypass pipe 22. When the valve 23 is turned on, the bypass pipe 22 is opened and the injection pipe 19 is opened.
And the leakage pipe 21 and, when turned off, the bypass pipe 2
2 is closed so that the injection pipe 19 and the leakage pipe 21 are shut off.

A pulsar (not shown) and a top dead center sensor 24 for detecting the position of the top dead center of the piston are provided on the crankshaft of the engine or on a shaft parallel to the crankshaft rotating in synchronization with the crankshaft. . A rotation sensor 26 for detecting the rotation speed is provided on the crankshaft of the engine,
Fuel injection pump 12 or accelerator pedal (not shown)
Is provided with a load sensor 27 for detecting an engine load. The detection outputs of the top dead center sensor 24, the rotation sensor 26, and the load sensor 27 are connected to the control input of the controller 28, and the control output of the controller 28 is connected to the valve 23. The rotation sensor 26 is stored in the memory of the controller 28.
The value N ₁ and L ₁ predetermined for comparing a detection value L of the detected value N and the load sensor of is stored.

The operation of the thus configured fuel injection rate control device will be described. The fuel in the fuel tank 15 is supplied to the fuel injection pump 1 by the feed pump 11 through the filter 17.
The fuel is then sent from the injection pump 12 to the fuel injection nozzle 13 via the injection pipe 19. When the rotational speed N of the engine is equal to or less than a predetermined value N ₁ and the load L of the engine is equal to or less than a predetermined value L ₁ , the controller 28 starts injection of fuel into the cylinder based on a detection signal of the top dead center sensor 24. At almost the same time, the valve 23 is turned on, and the bypass pipe 22 is turned on.
open. The injection pipe 19 and the leakage pipe 21 are communicated with each other, and a part of the fuel pumped by the injection pump 12 escapes from the leakage pipe 21 to the fuel tank 15. When the predetermined time T has elapsed, the controller 28 turns off the valve 23, closes the bypass pipe 22, and cuts off the injection pipe 19 and the leakage pipe 21. As shown in FIG. 3, the fuel injection rate decreases only during the time T, and after the time T elapses, the injection rate sharply increases.
As a result, the injection amount at the initial stage of injection is kept low, the injection amount of fuel relative to the intake air amount is prevented from being excessive, and the emission of nitrogen oxides is reduced. In FIG. 3, the broken line indicates the injection characteristic when the bypass pipe 22 is not opened.

In the embodiment, a pipe having a constant inner diameter is used as the injection pipe. However, this is an example, and as shown in FIG. 4, the injection pipe 59 is directed from the fuel injection pump 12 to the fuel injection nozzle 13 as shown in FIG. A tapered tube having a tapered inner diameter may be used. In this case, it is possible to feed a higher-pressure fuel to the injection nozzle 13 and control the injection rate in a high-load region to simultaneously reduce nitrogen oxides and black smoke.

[0011]

As described above, according to the present invention, a bypass is provided between an injection pipe for pumping fuel from a fuel injection pump to a fuel injection nozzle and a leakage pipe for returning fuel overflowing from the injection nozzle to a fuel tank. Connect the pipes
A valve that can open and close the bypass pipe is provided in the middle of the bypass pipe, and the controller opens and closes the valve based on the detection signals of the top dead center sensor, the rotation sensor, and the load sensor. The injection rate is kept low and the emission of nitrogen oxides is reduced. The provision of this device also enables pilot injection and the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel injection rate control device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is an injection characteristic diagram of a fuel injection pump.

FIG. 4 is a sectional view corresponding to FIG. 2, showing another embodiment.

[Explanation of symbols]

 Reference Signs List 12 fuel injection pump 13 fuel injection nozzle 15 fuel tank 19,59 injection pipe 21 leakage pipe 22 bypass pipe 23 valve 24 top dead center sensor 26 rotation sensor 27 load sensor 28 controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02M 55/02 350 F02M 55/02 350E 350P 350U

Claims (1)

(57) [Claims] 1. A fuel injection pump (12) to a fuel injection nozzle
(13) an injection pipe (19) for pressure-feeding fuel, and the injection nozzle (1).
A leakage pipe (21) for returning the fuel overflowing from 3) to the fuel tank (15), and a bypass pipe having one end branched from the injection pipe (19) and the other end joined and connected to the leakage pipe (21). (22), a valve (23) provided in the middle of the bypass pipe (22) and capable of opening and closing the bypass pipe (22), and a top dead center sensor (24) for detecting the position of the top dead center of the piston of the engine. When,
A rotation sensor (26) for detecting a rotation speed of the engine,
A load sensor (27) for detecting a load of the engine, the top dead center sensor (24), a rotation sensor (26), and a load sensor (27)
And a controller (28) for controlling the valve (23) based on the respective detection signals.