JPH08121255A - Fuel control valve - Google Patents

Abstract

PURPOSE: To supply the set flow rate of fuel under the set pressure stably. CONSTITUTION: A fuel control valve 6 is a control valve which controls a flow rate of fuel to be supplied to a combustion nozzle by changing a degree of opening of the valve. It is provided with a valve main body 10, a valve seat 12 provided in the valve main body 10, a valving element 13 which engages with the valve seat 12 and has two continuous tapered faces whose tilt angles increase toward a tip of the valve seat 12, and a valve actuator 14 which drives the valving element 13 for the valve seat 12 so as to change the degree of opening of the valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control valve, and more particularly to a fuel control valve which controls the flow rate of fuel supplied to an engine by changing the valve opening.

[0002]

2. Description of the Related Art In a fuel system of an engine such as a gas turbine engine, by bypassing a part of fuel such as kerosene or light oil discharged from a pump and controlling the bypass flow rate, It is common practice to control the supply. A fuel control valve for controlling a bypass flow rate of this kind generally includes a valve body having a valve seat and a valve body engaging with the valve seat, and a hydraulic valve actuator for driving the valve body toward and away from the valve seat. And an electric / oil servo valve for controlling the valve actuator. The valve body has a tapered surface at the tip that engages with the valve seat. When this valve body moves inside the valve seat, the opening area changes and the valve opening changes.

This fuel control valve is feedback-controlled to constantly control the fuel supply flow rate to be constant. In other words, in this fuel control valve, when the deviation electric signal generated due to the difference between the actual fuel supply amount to the combustion nozzle of the gas turbine and the set flow rate is amplified and applied to the electric / oil servo valve, its current value is increased. A hydraulic fluid with a flow rate proportional to flows to the valve actuator. As a result, in order to control the bypass flow rate, the valve element is positioned at a predetermined position according to the difference, the valve opening changes, and the fuel supply amount matches the set flow rate.

[0004]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since liquids with low viscosity such as kerosene and light oil are handled, the rate of change in the flow coefficient per stroke of the valve body tends to increase. When the rate of change of the flow coefficient increases, hunting may occur. This is because when the rate of change in the flow rate coefficient increases, the change in the bypass flow rate with respect to the change in the valve opening due to movement of the valve element increases, and even if the flow rate of the control hydraulic fluid changes slightly, the bypass flow rate changes. Because it changes a lot. If hunting occurs, the feedback control becomes unstable and it becomes impossible to supply fuel stably.

In order to solve this problem, it is conceivable to reduce the inclination angle of the tapered surface and reduce the rate of change in the flow coefficient per stroke. However, if the rate of change of the flow coefficient is simply reduced, the pressure loss becomes too large and the pressure in the fuel line cannot be kept within the set pressure. An object of the present invention is to make it possible to stably supply a set flow rate of fuel within a set pressure.

[0006]

A fuel control valve according to the present invention is a fuel control valve for controlling a flow rate of fuel supplied to an engine by changing a valve opening degree. The fuel control valve is provided in a valve body and a valve body. A valve seat, a valve body that engages with the valve seat, and has a plurality of continuous tapered surfaces that gradually increase the inclination angle toward the tip thereof, and the valve body is used as the valve seat to change the valve opening degree. And a valve drive unit that drives the same.

[0007]

In the fuel control valve according to the present invention, when the valve body engaged with the valve seat is gradually separated from the valve seat by the valve drive portion, the opening area changes and the valve opening changes. At this time, since the inclination angle of the tapered surface increases toward the tip, the rate of change of the flow coefficient gradually increases with respect to the movement of the valve element.

Here, the rate of change of the flow coefficient increases at the tip of the valve body and gradually decreases toward the base end side, so that the flow rate coefficient per stroke changes on the taper surface on the base end side of the valve body. Can be made small and can be stably controlled to the set flow rate, and the change in the flow rate coefficient per stroke can be made large on the taper surface on the tip side, so that the pressure loss can be made small and the pressure can be maintained within the set pressure.

[0009]

FIG. 1 shows a fuel supply system adopting an embodiment of the present invention. The fuel supply system includes a fuel tank 1 for storing fuel such as kerosene and light oil, and a fuel pump 2.
And a fuel control valve arranged in a distribution valve 4 for distributing the oil discharged from the fuel pump 2 to a plurality of combustion nozzles 3, and a branch pipe 5 branching toward the tank between the fuel pump 2 and the distribution valve 4. Valve 6 and. An electric / oil servo valve 7 is attached to the fuel control valve 6. A hydraulic power source (not shown) is connected to the electric / oil servo valve 7. The electric / oil servo valve 7 controls the flow rate of the hydraulic oil supplied from the hydraulic source by an electric signal according to the deviation between the set flow rate of fuel and the actual flow rate.

As shown in FIG. 2, the fuel control valve 6 includes a valve body 10, a valve seat 12 arranged at a fuel supply port 11 of the valve body 10, a valve body 13 engaging with the valve seat 12. Disc 1
3 and a valve actuator 14 for driving the valve 3. The valve body 10 is formed with a fuel outlet port 20 and an L-shaped flow passage 21 that connects the fuel supply port 11 and the fuel outlet port 20.

As shown in FIG. 3, the valve body 13 is a member having a truncated cone shape at its tip, and has two taper surfaces 22 and 23 having different inclination angles and a large inclination angle for engaging the valve seat 12. The seat surface 24 is provided at the tip. The tapered surface 22 is
It is formed at the tip of the valve element 13, and has an inclination angle of 8.
It is 5 °. The tapered surface 23 is formed continuously with the tapered surface 22, and has an inclination angle of 6 °, for example. here,
The inclination angle of the conventional fuel control valve is 8.5 °, which is the same as that of the tapered surface 22.

As shown in FIG. 2, the valve actuator 14 is a hydraulic cylinder consisting of a piston 25 and a cylinder case 26. Piston rod 2 of piston 25
A valve body 13 is attached to the tip of 5a. The electric / oil servo valve 7 supplies hydraulic oil to both oil chambers sandwiching the piston 25 of the valve actuator 14. Next, the operation of the above embodiment will be described.

When a current signal corresponding to the deviation between the set flow rate of fuel and the actual flow rate is applied to the electric / oil servo valve 7, the hydraulic pressure of the flow rate is supplied to the valve actuator 14 and the valve body 13 is It moves to the left and right in FIG. 2 and stops at the set position. Two tapered surfaces 22 and 23 are formed at the tip of the valve body 13. The taper surface 23 has a gentle inclination angle, and the taper surface 22 has a larger inclination angle than the taper surface 23. Therefore, in the tapered surface 23, the rate of change in the flow coefficient is small, and in the tapered surface 22, it is large.

Actual flow coefficient C for movement of valve pair 13
The rate of change of v is shown in FIG. FIG. 4 shows the flow rate when the valve body is moved from the fully closed state shown by the two-dot chain line in FIG. 2 where the seat surface 24 of the valve body 13 is in contact with the valve seat 12 to the fully opened state shown by the solid line in FIG. The relationship between the coefficient and the stroke is shown. The solid line in FIG. 4 shows the change in the flow coefficient of the fuel control valve according to the present embodiment, and the dotted line shows the change in the conventional example.

As is clear from this graph, the change in the flow coefficient on the tapered surface 23 from the stroke of 0 mm to the vicinity of 28 mm is as follows.
It is smaller than the change in the flow coefficient on the tapered surface 22 up to m. As described above, when the rate of change in the flow rate coefficient is small, even a slight change in the flow rate occurs with respect to the change in stroke, and even if the flow rate of the hydraulic oil applied to the valve actuator 14 changes slightly, the bypass flow rate changes. Does not fluctuate significantly. Therefore, stable control of the fuel flow rate can be performed. Moreover, since the rate of change in the flow coefficient at the tapered surface 22 at the tip is large, pressure loss is less likely to occur, and the fuel pressure can be maintained within the set pressure. Other Embodiments (a) As a valve actuator, another actuator such as an air cylinder or an electric cylinder may be used instead of the hydraulic cylinder. (B) The size of the tilt angle is an example, and the tilt angle may be arbitrarily changed according to the type of fuel. (C) The number of tapered surfaces is not limited to two, and may be any number as long as it is 2 or more.

[0016]

In the fuel control valve according to the present invention, the rate of change in the flow coefficient increases at the tip of the valve body and gradually decreases toward the base end side. Can reduce the change in flow rate coefficient per stroke and can stably control the set flow rate.
On the tapered surface on the tip side, it is possible to increase the change in the flow coefficient per stroke, reduce the pressure loss, and maintain the pressure within the set pressure.

[Brief description of drawings]

FIG. 1 is a system diagram of a fuel supply system adopting an embodiment of the present invention.

FIG. 2 is a sectional view of a fuel control valve.

FIG. 3 is a partial side view of the valve body.

FIG. 4 is a graph showing a relationship between a flow coefficient and a stroke.

[Explanation of symbols]

 6 Fuel Control Valve 12 Valve Seat 13 Valve Body 14 Valve Actuator 22, 23 Tapered Surface

Claims (1)

[Claims] 1. A fuel control valve for controlling a flow rate of fuel supplied to an engine by changing a valve opening, a valve body, a valve seat provided on the valve body, and an engagement with the valve seat, A valve body having a plurality of continuous tapered surfaces whose inclination angle gradually increases toward the tip thereof, and a valve drive section which drives the valve body toward the valve seat so as to change the valve opening degree. , A fuel control valve with.