JPS60162050A - Fuel valve provided with injection valve opening pressure regulator - Google Patents

Abstract

PURPOSE:To secure such injection valve opening pressure as being suitable for a driving state, by leading governor setting pressure being small in pressure variations into a selector valve and making it so as to regulate the injection valve opening pressure while decreasing a momentary variation in a valve opening pressure select signal, especially preventing any irregularities in the injection-valve opening pressure in and around a selecting point from occurring. CONSTITUTION:Fuel being fed by a fuel-injection pump 14 under pressure is fed to a fuel valve 1 via an injection pipe 13, pushing up a needle valve 11 of the fuel valve against the resilience of a needle valve spring 10, and spouted to the inside a cylinder. In an injection-valve pressure regulator 22, a lower end of its piston 8 comes into contact with an upper end surface of an upper spring bearing 9 of the needle valve spring 10, whereby the regulator 22 varies setting load of the needle valve spring 10 with pressure in a hydraulic fluid to be fed to an oil chamber 16 of a cylinder 15, making the valve opening pressure of the needle valve 11 into variations. Therefore, high valve opening pressure is maintained by a selector valve 6a as far as a portion for an engine speed range interval where normal injection takes place at high valve opening pressure, so that in time of the high valve opening pressure, injection of the fuel valve 1 takes place at low l valve opening pressure at regions where irregular injection occurs or injection pressure is to high.

Description

[Detailed description of the invention] This invention relates to a valve pressure adjustment device.

In recent years, diesel engines have begun to adopt systems that change the opening pressure of the fuel valve depending on the engine operating conditions.

Conventionally, this type of fuel valve opening pressure adjustment device has been provided with a method that changes the mounting load of the fuel valve spring by detecting the engine speed or the injection amount of the fuel injection valve (i.e., the output amount of the governor). It had been.

However, in the case of such conventional systems, because the input signals to the valve opening pressure regulating device (engine speed, governor output, etc.) fluctuate, similar switching operations occur near the valve opening pressure switching point. .

There was a problem that the valve opening pressure was difficult to stabilize.

The present invention has been made in view of the above, and is a fuel valve equipped with a valve opening pressure adjustment device that can obtain an opening pressure of 1° adapted to the operating condition of the engine by preventing fluctuations in the valve opening pressure adjustment factor. The purpose is to provide

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 1 indicates a fuel valve attached to a cylinder force bar l2, 2 indicates an engine control device, 2a indicates a control handle, and 5 indicates an engine control device. A governor 3 adjusts the amount of fuel in accordance with the speed of the controller, and 3 is a pressure regulating valve r that outputs to the governor 5 a governor set pressure corresponding to the position of the cam 4 that is linked to the above-mentioned control node /v2a.
.

14 is a fuel injection pump whose fuel injection amount is adjusted by the governor 5;

The fuel pressure-fed by the fuel injection pump 4 is sent to the fuel valve 1 through the injection pipe 13, and the needle valve 11 of the fuel valve 1 is pushed up against the elasticity of the needle valve spring 10 to be injected into the cylinder.

22 is a valve opening pressure adjustment device attached to the head of the fuel valve 10;
Fluid pressure cylinder 15. The piston 78 is provided with a piston 78 that slides back and forth within the cylinder 15.

In the valve opening pressure adjusting device 22, the lower end of the vist 78 is in contact with the upper end surface of the upper spring receiver 9 of the needle valve spring 10, and 1i1 working fluid (hydraulic oil) is supplied into the oil chamber 16 of the cylinder 15-. The mounting load of the needle valve spring IO is changed by the pressure of , and the opening pressure of the needle valve 11 is changed.

6 is a valve opening pressure control unit, which includes two adjustable pressure switching valves 6
a, 6b, a manual switching valve 6C, etc.

Adjustable pressure switching valves 6a, 6L+ of the valve opening pressure control unit 6
is supplied via a governor setting pressure (air pressure) outputted from a pressure regulating valve 3 in the control device 2 or an air passage 20a branched from a governor setting air passage 20.

The adjustable pressure switching valves 6a and 6b adjust the pressure of the working fluid from the fluid pressure source 17 and supply it through the oil passage 21 into the oil chamber 16 of the valve opening pressure adjustment device 22.

Note that 18 is a control air source for the control device 2.

FIG. 2 shows the opening pressure characteristics of the fuel valve in the engine with the above configuration. In the figure, ■ indicates an operating region where irregular injection is likely to occur in the fuel valve 1 at high valve opening pressure, ■ indicates an operating region where normal injection is performed at high valve opening pressure, and ■ indicates injection pressure at high valve opening pressure. is too high.

The switching valve 6a is switched when the governor set pressure output from the pressure regulating valve 3 reaches P1 in FIG.
The working fluid corresponding to r2 is sent through the oil passage 21 into the oil chamber 16 of the valve opening pressure adjustment device 22.

As a result, the upper spring holder 9 is pushed down together with the piston 8, the mounting load of the needle valve spring 10 increases, and the valve opening pressure rises to PF3.

When the governor set pressure reaches P2 in FIG. 2, the switching valve 6b is switched and the working fluid corresponding to the low valve opening pressure PfI is sent to the oil chamber 16 of the valve opening pressure adjusting device 22.

The valve opening pressure of the needle valve II is maintained at a low valve opening pressure Pf'+.

As mentioned above, the high valve opening pressure 1'f2 is maintained by the switching valve 6a only in the rotation speed region N+6-Nz6 (region ■ in Figure 2) where normal injection is performed at the high valve opening pressure Pf2, and the high valve opening pressure In Pr2, in the region where irregular injection occurs (region in Figure 2) or in the region where the injection pressure is too high (region ◎ in Figure 2), the fuel valve l will inject at a low amount of fuel (pressure 1) fl. Become.

The switching points of the switching valves 6m and 6b can be changed by adjusting the control device 2 and the switching valves 6a and 6b.

During operation at the high valve opening pressure 1.r2, if it becomes necessary to suddenly release the high valve opening pressure, the manual switching valve 6C is operated to release the high valve opening pressure.

The present invention is constructed as described above.2 According to the present invention, since the valve opening pressure is adjusted by guiding the governor setting pressure with little pressure fluctuation to the switching valve, the valve opening pressure switching signal is Instantaneous fluctuations are small, preventing the valve opening pressure from becoming unstable especially near the switching point, and making it possible to obtain a valve opening pressure suitable for the operating conditions in all operating ranges.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is a system diagram thereof, and FIG. 2 is a diagram showing the operation.

Claims (1)

[Claims] In a diesel engine equipped with a fuel valve whose opening pressure can be adjusted, a piston operated by the pressure of two working fluids is used to change the load of the needle valve of the fuel valve. A valve opening pressure adjustment device that adjusts the opening pressure of the valve, and a governor setting fluid branched from a governor operation fluid line that connects the governor of the engine and the operation device are introduced to adjust the valve opening pressure above. 1. A valve opening pressure regulating device comprising: a switching valve for switching the pressure of working fluid to the regulating device; -Fuel valve.