JPH0420998Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas-fired diesel engine.

[Conventional technology]

7-8 show schematic diagrams of conventional gas injection valves. The gas injection valve is composed of a cap nut 3 that fixes the nozzle 1 and the main body 2, a needle valve 4 that operates inside the cap nut 4, a thrust rod 5, a compression spring 6, and a spring force adjusting nut 7. The nozzle 1 has hollow parts 21, 22, 23 between the needle valve 4 and the sliding part,
Furthermore, these cavities have communication holes 31 on the nozzle side,
32, 33 and communicating holes 41, 42, 43 on the main body side communicate with the outside.

Fuel gas is supplied to the cavity 21 from the outside, and when the needle valve 4 leaves its seat 29, the fuel gas is injected into the engine fuel chamber from the nozzle 30. The cavity 22 is a part on which high-pressure hydraulic oil from the outside acts, and the needle valve 4 has a shape in which the upper cross-sectional area is larger than that of the cavity 22. When the operating force of the hydraulic fluid against the needle valve 4 becomes stronger than the force of the spring 6 that presses the needle valve 4 against the seat 29 via the thrust rod 5, the needle valve 4 is pushed upward and the inside of the cavity 21 is pushed up. Inject fuel gas into the combustion chamber. A fuel injection pump commonly used in diesel engines is used as a high-pressure hydraulic pressure generator. The cavity 23 is a seal oil reservoir, and a pressure higher than the gas pressure is applied to prevent fuel gas from entering the hydraulic oil system.

The gas injection valve is constructed as described above, and fuel gas is constantly supplied to the cavity 21, which is a needle valve gas reservoir, during operation, and is injected into the combustion chamber in each cycle.

[Problem that the invention attempts to solve]

However, when the needle valve becomes stuck and cannot be properly seated, the fuel gas constantly flows out from the nozzle due to the supply pressure, resulting in a dripping state. The fuel gas that flows out during the scavenging stroke is discharged to the outside along with the exhaust gas, and the fuel gas that entered the cylinder during the compression period leaks into the crankcase, causing pre-ignition and knotting when it is burned in the cylinder. Cause. To prevent this, constantly monitor this,
It is necessary to detect combustible gases in exhaust gas and constantly monitor combustion conditions, but both require large-scale equipment and require clear identification of normal and abnormal conditions depending on all operating conditions. is difficult and has many problems. Additionally, a separate gas supply line shutoff device is required.

The purpose of the present invention is to solve the problems of the conventional device as described above, and to solve the problem of the above-mentioned conventional device. It is an object of the present invention to provide a gas injection valve device in which the shutoff valve is automatically closed at times to ensure safe operation.

[Means for solving problems]

The gas injection valve device of the present invention utilizes the oil pressure of the needle valve seal oil of the gas valve, and also provides a notch on the outer periphery of the needle valve for pressure transmission such that the passage area changes by lift. The structure is such that the gas injection valve is opened and closed by the seal oil pressure that passes through the section.

When the needle valve is stuck and not seated, the notch is narrow, so there is a large pressure loss and the seal oil pressure decreases, and the gas cutoff valve in the gas supply path is closed. However, during normal operation, the needle valve lifts. There is no problem as the period is short.

[Effect]

If the needle valve of the gas valve becomes stuck and an abnormality occurs, it is safe because the gas cutoff valve in the gas supply pipe is closed. The gas valve is also shut off when an abnormality such as a leak occurs in the seal oil system and the seal oil pressure decreases.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

Fig. 1 is a longitudinal sectional view of the embodiment, Fig. 2 is an enlarged view of the needle valve, Fig. 3 is a detailed view of the gas cutoff valve, Fig. 4 is an explanatory diagram of the opening area of the notch provided in the needle valve, FIG. 5 is an explanatory diagram of the opening (passage) area and pressure of each part of the embodiment, and FIG. 6 is an explanatory diagram showing temporal changes in needle valve lift, notch opening area, and shutoff valve control oil pressure during operation. In FIGS. 1 and 2, 1 is a nozzle, 2 is a main body, 3 is a cap nut, 4 is a needle valve, 5 is a thrust rod, 6 is a compression spring, 7 is a compression spring pressure adjustment screw,
21 is a gas reservoir, 22 is a hydraulic oil reservoir, and 23 is a seal oil reservoir.

In the needle valve 4, hydraulic pressure acts on a hydraulic oil reservoir 22,
When the pressure overcomes the biasing force of the spring 6, the fuel gas rises from the seat 29 and the fuel gas in the gas reservoir 21 flows into the sac part 28.
It is then injected from the nozzle 30. A seal oil reservoir 23 is located between the gas reservoir 21 and the hydraulic oil reservoir 22, and the seal oil pressure adjusted to be higher than the gas fuel supply pressure prevents the gas fuel from entering the hydraulic oil system. In the present invention, one or more notches 25 are cut out on the outer periphery of the needle valve 4 facing the seal oil reservoir 23 of the nozzle 1, and the notch area increases toward the top. A diameter portion 24 is provided. The length of the narrow diameter part is greater than or equal to the maximum lift of the needle valve, and a pressure outlet hole 34 is provided in the nozzle body 1 near the upper end of the narrow diameter part 24, and the injection valve body 2
It leads to the top of the. In the upper part of the injection valve body 2, the passage 44 is branched, and one side is collected into the seal oil tank via the throttle 53, while the other side is communicated with the gas cutoff valve 80.

Next, details of the shutoff valve 80 will be explained with reference to FIG. 3.

The gas shutoff valve 80 is composed of a gas inlet section 101, a shutoff valve body 102, and a control oil inlet section 103. A gas shutoff valve 110 slides in the passageway 122 of the shutoff valve body 102 and has a head 1.
11 is attached so as to be pressed against the tapered seat 105 by gas pressure and a compression spring 113. Also, on the opposite spring side of this gas shutoff valve 110,
The piston 130 is the stopper 1 of the shutoff valve body 102
06 and the control hydraulic inlet part 103 so as to be slidable. The piston 130
It has a seal ring 133 for sealing gas and control hydraulic pressure during sliding, and a protrusion 131 for pushing up the gas shutoff valve 111 on the gas passage side. Also, the gas outlet passage 123 of the gas cutoff valve body 102 and the passage 1 of the control oil inlet section 103
24 communicates with the gas injection valve main body 2 via communication pipes 61 and 64.

FIG. 4 shows a relationship diagram between the opening area of the notch 25 of the needle valve 4 and the needle valve lift, and FIG. 5 shows the relationship between the seal oil pressure and the cross-sectional area of each part in the path through which the seal oil pressure propagates. That is, the pressure loss in the seal oil reservoir 23 as the pressure source of the shutoff valve is from the seal oil reservoir to the seal oil return passage 54 which is the open end, where A is the seal oil reservoir 23 and B is the notch 25. , C indicates the narrow diameter portion 24, D indicates the nozzle main body passage 34, E indicates the gas valve main body passage 44, F indicates the throttle 53 after branching, and G indicates the seal oil return passage 54. The pressure at section E becomes the control oil pressure for the shutoff valve 80. The area S _t of the throttle portion 53 is smaller than the opening area S ₁ of the notch when the needle valve is seated, and is set to a value equivalent to the opening area S ₂ when the needle valve is at maximum lift.

Next, these effects will be explained.

When the needle valve 4 is seated, the pressure loss in the notch 25 is relatively small as shown by the solid line B in Figure 5b, but when the needle valve 4 is lifted, the opening area of the notch is _S1 . It is located in the middle of S ₂ and gradually becomes smaller as the height of the lift increases.

The solid lines in FIG. 5b show the pressures at each part when the seat is seated, and the broken lines show the pressures at each part when the needle valve seizes and fully lifts and stops.

FIG. 6 shows the movement of the needle valve lift during operation, the opening area of the notch, and the temporal changes in the E section pressure in FIG. As a result, it temporarily decreases, but quickly recovers and repeats this process.
If the needle valve 4 becomes stuck, the control oil pressure will drop significantly as shown by the broken line in the figure.

Next, the operation of the gas cutoff valve 80 will be explained.

When the needle valve is operating without any abnormality, the control oil pressure is higher than the set value, so the piston 130 overcomes the gas pressure and the spring force of the gas shutoff valve spring 113 and pushes the gas shutoff valve 110 upward. As a result, gas from the gas inlet 60 flows out to the gas outlet 61 through the open passage. Therefore, if the operating pressure of the gas cutoff valve 80 is set to a value psd slightly lower than the control oil pressure at the time of seating, as shown in FIG. 5, when the needle valve 4 becomes stuck during operation, the pressure shown in FIG. When the pressure decreases as shown in E, and this acts on the gas shutoff valve 80, the gas shutoff valve 110 closes due to the pressure of the gas itself and the pressing force of the spring 113, preventing fuel gas leakage and accidents. be able to.

In this example, the gas line is closed directly using the control oil pressure, but it is also possible to detect the control oil pressure with a pressure sensor and close the gas supply line electrically via a relay or by using a pressure switch. .

[Effect of idea]

Since the present invention is constructed as described above, the gas cutoff valve provided in the gas supply passage is opened when the gas injection valve is operating normally, and is opened when the gas injection valve is stuck. The gas cutoff valve is automatically closed, allowing safe driving and completely preventing accidents.

[Brief explanation of the drawing]

Figures 1 to 6 are related to the present invention; Figure 1 is a longitudinal sectional view of the embodiment, Figure 2 is an enlarged view of the needle valve, Figure 3 is a detailed view of the gas cutoff valve, and Figure 4 is the needle valve. Fig. 5 is an illustration of the cross-sectional area of each part in the path through which seal oil pressure propagates and the situation of seal oil pressure loss, and Fig. 6 is an illustration of the needle valve lift and the opening area of the notch over time. Figures 7 and 8 show a conventional example of a gas injection valve, Figure 7 is a longitudinal cross-sectional view of the plane including the seal oil passage, and Figure 8 shows the gas supply pipe and its operation. FIG. 3 is a longitudinal sectional view taken along a plane including an oil passage. 4... Needle valve, 6... Spring, 21... Needle valve gas reservoir, 22... Hydraulic oil reservoir, 23... Seal oil reservoir, 25... Notch, 44, 64... Control oil path, 80... ...Gas shutoff valve.

Claims (1)

[Scope of utility model registration request] A needle valve that opens and closes depending on the pressure difference between the pressure of the hydraulic oil supplied to the hydraulic oil reservoir and the spring force to inject gaseous fuel, and a needle valve provided at an intermediate portion between the hydraulic oil reservoir and the gas reservoir of the needle valve. In a gas injection valve equipped with a seal oil reservoir, a notch is provided on the outer periphery of the needle valve, the lower end of which can communicate with the seal oil reservoir, and whose area decreases as the needle valve lifts. A gas injection valve device comprising: a control oil passage communicating with the upper part of the gas injection valve; and a gas cutoff valve that opens and closes a gas supply passage to the gas injection valve based on changes in control oil pressure connected to the control oil passage.