JPS60206972A - Fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To improve engine efficiency by having injection timing variable through the use of a rotation phase adjuster and also by having injection start pressure and injection rate variable by means of an intensifier placed between a fuel supply pump and an injection nozzle. CONSTITUTION:When a cam shaft 5 is rotated by an engine crank shaft 1 through a reduction device 2, each of cams 8-10 activates a fuel supply pump 11 and hydraulic switching valves 12 and 13. First of all, the hydraulic switching valve 12 will close and the hydraulic switching valve 13 will open, and at the same time the fuel from the pump 11 will be supplied to the high pressure side 16 of an intensifier 15. Secondly, the hydraulic switching valve 13 will close and the hydraulic switching valve 12 will open to lead the hydraulic oil from its source 17 to the low pressure side 19 of the intensifier. Accordingly, a piston 20 within the intensifier 15 will be pushed downward and the pressure fuel at the high pressure side will be injected through an injection nozzle 22. In such a case, adjustment of fuel injection timing will be done by staggering the phase of shafts 1 and 5 by a rotation phase adjuster 4.

Description

[Detailed Description of the Invention] This invention aims to improve the engine efficiency of a diesel engine, and
In order to enable efficient combustion even with high-viscosity, low-quality oil, the characteristics of fuel oil injection (hereinafter simply referred to as injection) into the cylinder of an engine, including injection timing, injection amount, injection rate, and injection start pressure, are determined. This invention relates to a fuel injection device for a diesel engine that can be changed and adjusted during operation.

Conventional fuel injection devices for diesel engines consist only of a fuel supply pump drive cam and a fuel supply pump, and because the fuel injection rate and injection pressure cannot be changed, the fuel spray condition is poor and stable spray cannot be achieved at low loads. Therefore, there was a drawback that the engine efficiency was poor.

In order to eliminate such drawbacks, the present invention uses a rotational phase adjuster to make the injection timing variable, and also provides a pressure intensifier to increase the pressure of fuel oil between the fuel supply pump and the injection nozzle. An object of the present invention is to obtain a fuel injection device for a diesel engine that can improve engine efficiency by making injection starting pressure and injection rate variable.

The invention will now be explained by way of illustrative embodiments.

As shown in Fig. 1, a camshaft 5 is connected to a shaft 3 connected to an engine crankshaft 1 through a reduction gear 2 via a phase adjuster 4 that changes only the rotational phase while maintaining the rotational speed. Join. The phase adjuster 4 can be realized, for example, as follows. That is, as shown in FIG. 2, two sets of planetary gears with the same reduction ratio are symmetrically connected, the outer ring gear 6 of one planetary gear is fixed, and the phase position of the outer ring gear 7 of the other planetary gear is fixed. By finely adjusting , it is possible to change the rotational phase of the camshaft 5 while keeping the rotational speed of the camshaft 5 the same as the rotational speed of the shaft 3.

In FIG. 1, a fuel supply pump drive cam 8 and a hydraulic on-off valve drive cam 9 and 10 are attached to the camshaft 5, and drive the fuel supply pump 11 and hydraulic on-off valves 12 and 13, respectively.

The fuel supply pump 11 is connected to a pressure intensifier 15 through a check valve 14.
Fill the high pressure control 6 with fuel.

Pressurized hydraulic oil (hereinafter simply referred to as pressure oil) from the source 17 is guided to the hydraulic on-off valve 12 via the pressure regulator 18 .

The hydraulic on-off valve 12 opens when driven by the hydraulic on-off valve drive cam 9 and guides pressure oil to the low pressure side I9 of the pressure intensifier 15.

When the pressure intensifier 15 pressurizes the low pressure side with pressure oil, the piston 20 moves and generates pressure on the high pressure side according to the area ratio of the low pressure side and high pressure side of the piston, and the fuel filled in the high pressure side 16 is discharged. The fuel is pressurized and fed to the injection nozzle 22, and the fuel is injected.

Further, it is preferable that the injection nozzle 22 is provided with a valve opening pressure adjustment mechanism. In this valve opening pressure adjustment mechanism, the injection nozzle is closed by a needle valve 23, and the metal valve 23 is held down by hydraulic pressure applied to a piston 25 behind it via a spring 24. There are other ways to adjust the side valves, such as by using a motor.

The fuel guided to the injection nozzle chamber 21 is forced into the needle valve 2 by its pressure.
3 and inject into the engine cylinder from the nozzle 22. Injection nozzle chamber 21 necessary for fuel injection at this time
This pressure is called the injection start pressure.

Pressure oil applied to the piston 25 is guided from the hydraulic source 17 via a pressure regulator 26 .

The pressure oil on the low-pressure side 19 of the pressure intensifier after the piston 20 has been pressurized is released through the hydraulic on-off valve 13 driven by the hydraulic on-off valve drive cam lO, and returned to the tank of the oil pressure source 17.

Next, the present invention will be explained in detail.

The fuel supply pump drive cam 8 and the two hydraulic on-off valve drive cams 9.10 drive the fuel supply pump 11 and the hydraulic on-off valves 12.13, respectively, in the following order as the camshaft 5 rotates. is set to . Initially, the hydraulic on-off valve 12 is closed, then the hydraulic on-off valve 13 is opened, and the fuel supply pump 11 supplies a predetermined amount of fuel to the pressure intensifier high pressure side 16.
Fill it. When the filling of fuel into the high pressure side 16 of the pressure intensifier is completed, the hydraulic on-off valve 13 is closed, and when the time for fuel injection comes, the hydraulic on-off valve 12 is opened to guide the pressure oil to the low pressure side 19 of the pressure intensifier. The pressure intensifier 15 pressurizes the fuel on the high-pressure side 16 and the fuel in the injection nozzle chamber 21 connected thereto by the movement of its piston 20 . The pressurized fuel pushes up the side valve 23 and starts to be injected from the nozzle 22 into the cylinder of the engine. The pressurization of the fuel continues until the intensifier piston 20 hits the end of the high pressure side 16, so that all of the fuel previously charged on the high pressure side 16 is injected. In this way, it returns to the initial state again, and the hydraulic opening/closing valve 1
2 is closed, and the hydraulic on-off valve 13 is opened to repeat fuel filling and injection.

The initial characteristics of fuel injection can be adjusted as follows.

The fuel injection timing is expressed by the phase position of the crank shaft 1 at the start of fuel injection. This adjustment can be achieved by shifting the phase relationship between the rotating shaft 3 and the camshaft 5 and the phase position of the outer ring gear 7 of the phase adjuster 4. That is, the cam mechanism is shifted in time due to a phase shift between the engine shaft and the cam shaft.

Regarding the adjustment of the injection quantity, the fuel injection quantity of the device in one go is equal to the fuel filling quantity of the high-pressure side 16 of the pressure intensifier by the fuel supply pump 11. Therefore, the fuel injection amount is adjusted by changing the fuel filling amount by the fuel supply pump 11.

The fuel injection rate, that is, the amount of fuel injected per unit time, can be adjusted by the fuel pressure in the injection nozzle chamber 21. This pressure is approximately the same as the pressure intensifier high pressure side 16,
It is proportional to the pressure on the pressure intensifier low pressure side 19.

The pressure on the low pressure side 19 of the pressure intensifier is approximately equal to the outlet pressure of the pressure regulator 18 attached to the outlet of the hydraulic power source 17. Therefore, the fuel injection rate can be adjusted by changing the pressure setting of the pressure regulator 18, thereby changing the pressure on the pressure intensifier low pressure side 19 and thus the fuel pressure in the injection nozzle chamber 21.

The injection start pressure is determined by the strength of the hydraulic pressure applied to the piston 25 pushing the needle valve 23 via the spring 24.

This hydraulic pressure setting is performed by a pressure regulator 26 attached to the outlet of the hydraulic system 7. Therefore, the injection start pressure can be adjusted by changing the pressure setting of the pressure regulator.

As explained in detail above, the diesel engine fuel injection device of the present invention can make the fuel injection rate and injection pressure sufficiently high even when the engine is under low load, so that the fuel spray condition is improved and the engine efficiency is improved. It has the great effect of improving the Further, the present invention has the great effect that the engine efficiency can be controlled extremely easily since the injection timing, injection amount, injection rate, and injection start pressure can be arbitrarily adjusted during engine operation.

Furthermore, because the present invention does not use electrical signals between cycles of fuel injection, if the present invention fails while the present invention is being adjusted by an automatic control device such as a computer that uses electrical signals, manual or This has the effect of allowing the device to be disconnected and continue operation. Furthermore,
The present invention enables fuel injection from the fuel supply pump directly from the injection nozzle by pushing up the piston of the pressure booster to the upper end and fixing it even when the hydraulic system stops functioning due to a failure of the hydraulic power source. The engine can be operated with proper fuel injection adjustment, and even if the hydraulic system of the present invention malfunctions, normal operation can be performed.

[Brief explanation of the drawing]

FIG. 7 is an explanatory diagram showing the operation of this fuel injection device,
FIG. 2 is an explanatory diagram showing the operation of the rotary phase adjuster. Explanation of phrase symbols

Claims (1)

[Claims] 1. A camshaft is attached via a rotational phase adjuster to a rotating shaft that is connected to the crankshaft of a diesel engine via a reduction gear, and a fuel supply pump driving cam and two camshafts are attached to this camshaft. a fuel supply pump driven by the fuel supply pump drive cam, and two hydraulic on-off valves respectively driven by the two hydraulic on-off valve drive cams, the hydraulic on-off valve drive cams being arranged so as to be able to inject fuel; a pressure intensifier whose low pressure side is connected to each of the hydraulic on-off valves by a hydraulic circuit and whose high pressure side is connected to the fuel supply pump via a check valve; and an injection nozzle device that injects fuel on the high pressure side of the pressure intensifier. A camshaft is attached via a rotational phase adjuster to a rotating shaft connected to the crankshaft of the diesel engine via a reduction gear device a, and a fuel supply pump driving cam is attached to this camshaft. and two hydraulic on-off valve drive cams arranged so as to be able to inject fuel, a fuel supply pump driven by the fuel supply pump drive cam, and two hydraulic on-off valve drive cams respectively driven by the - number of hydraulic on-off valve drive cams. a hydraulic on-off valve, a pressure intensifier whose low-pressure side is connected to each of the hydraulic on-off valves through a hydraulic circuit and whose high-pressure side is connected to the fuel supply pump via a check valve; and a hydraulic pressure intensifier that flows into the low-pressure side of the intensifier. A fuel injection device for a diesel engine, comprising a pressure regulator that makes the pressure variable, and a nozzle device that injects fuel on the high pressure side of the pressure booster. 3. A camshaft is attached via a rotational phase adjuster to the rotating shaft that is connected to the diesel engine crankshaft via a reduction gear, and a fuel supply pump driving cam and two hydraulic on-off valve driving cams are attached to this camshaft. a fuel supply pump driven by the fuel supply pump drive cam, two hydraulic on-off valves respectively driven by the two hydraulic on-off valve drive cams, and a low-pressure side connected to each of the above-mentioned hydraulic on-off valves. a pressure intensifier connected to the hydraulic on-off valve by a hydraulic circuit and whose high pressure side is connected to the fuel supply pump via a check valve; an injection nozzle device for injecting fuel on the high pressure side of the pressure intensifier; and the injection nozzle. A fuel injection device for diesel engines that has a valve opening pressure adjustment mechanism on the needle valve of the device.