JPH0250281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic valve opening/closing device used particularly in large internal combustion engines, and more specifically, to a hydraulic valve opening/closing device for use in large-scale internal combustion engines. This invention relates to a hydraulic exhaust valve opening/closing device that sometimes performs damping.

(Prior Art) In large internal combustion engines such as marine diesel engines, supply and exhaust valves are operated by hydraulic pressure. Among the supply and exhaust valves, especially the exhaust valve, when closed, jumps due to collision occur, which impedes the scavenging and air supply processes.

Therefore, when the exhaust valve closes, a damping effect is generated to prevent jumping.

This will be explained with reference to FIG. 2. The cam 1 overcomes the biasing force of the spring 2 to move the piston 3 up and down, and pressure oil is supplied to the hydraulic chamber 5 via the pipe 4. A hydraulic piston 7 is provided at the end of the exhaust valve 6, and receives hydraulic pressure from the hydraulic chamber 5 to open the exhaust valve 6 via a rod 8. A cylinder 10 forming a pneumatic chamber 9 is fixed to the rod 8, and compressed air is constantly introduced into the cylinder 10 to close the exhaust valve 6.

The hydraulic piston 7 is provided with a buffer recess 11,
In addition, the adjustment rod 12 fixed to the fuselage is located in the buffer recess 11.
is inserted into.

Now, when pressure oil is supplied to the hydraulic chamber 5 by the cam 1, the pressure within the hydraulic chamber 5 increases. This oil pressure moves the hydraulic piston 7 downward, and the exhaust valve 6 opens via the rod 8.

Next, when the pressure in the hydraulic chamber 5 becomes negative, the rod 8 moves upward together with the hydraulic piston 7 due to the compressed air force introduced into the pneumatic chamber 9, and the exhaust valve 6 closes.

When the exhaust valve 6 closes, the inside of the buffer recess 11 is compressed by the adjustment rod 12, and the inside of the buffer recess 11 becomes positive pressure. Therefore, the pressure oil gradually escapes between the adjustment rod 12 and the circumferential surface of the buffer recess 11, and the exhaust valve 6 is prevented from being closed in an impactful manner.

(Problem to be Solved by the Invention) However, according to the above configuration, when the exhaust valve 6 is opened, the inside of the buffer recess 11 becomes negative pressure, and the exhaust valve 6
This will impede the quick opening operation of the valve.

For this reason, it has become difficult to obtain good scavenging and exhausting processes, resulting in a drawback of lowering the thermal efficiency of the engine.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks, to perform the opening operation of the exhaust valve rapidly and smoothly, and further to perform the closing operation of the exhaust valve with a buffering effect.

(Means for Solving the Problems) The present invention is characterized by providing a hydraulic piston having a buffer recess at the rod end of the exhaust valve, and a hydraulic chamber for applying hydraulic pressure to the hydraulic piston. In a hydraulic exhaust valve opening/closing device that uses an adjustment rod inserted into a buffer recess of a piston to buffer the impact when the exhaust valve is closed, the adjustment rod is provided with a passage that communicates the buffer recess and the hydraulic chamber, A dart pot mechanism is provided in the passageway to facilitate the flow of pressure oil from the hydraulic chamber to the buffer recess, and to make it difficult to flow pressure oil from the buffer recess to the hydraulic chamber, and the dart pot mechanism forms a ripple-shaped flow path. It consists of a plurality of orifice plates.

(Function) Since the present invention is configured as described above, the inside of the buffer recess does not become negative pressure during the opening operation of the exhaust valve, and a rapid and smooth opening operation can be obtained.

(Example) This will be explained below using figures.

In the present invention, the adjusting rod is provided with a passage communicating the hydraulic chamber and the buffer recess, and the passage is provided with a dumppot mechanism consisting of an orifice plate, as shown in FIG. 1.

FIG. 1 is a sectional view showing one embodiment of the present invention. In addition, in FIG. 1, description of the same parts as the known structure shown in FIG. 2 will be omitted.

A plurality of orifice plates 33 are provided in a passage 32 provided in an adjustment rod 31, and the orifice plates 33 are held by a stopper 34.

In this case, the orifice plate 33 has a truss-like flow path shape 35, and the hydraulic chamber 5 is connected to the buffer recess 1.
1 side is easy, and the flow resistance from the buffer recess 11 to the hydraulic chamber 5 side is large. Therefore, the flow path shape 35 is enlarged on the hydraulic chamber 5 side and narrowed on the buffer recess 11 side, making it straight.

Therefore, when pressurized oil is now supplied into the hydraulic chamber 5 and the pressure becomes positive, the exhaust valve (not shown) opens.
At this time, the hydraulic chamber 5 passes through the orifice plate 33.
Pressure oil flows from the buffer recess 11 to the buffer recess 11, and since there is little resistance to the inflow of this pressure oil, the opening operation of the exhaust valve is rapid and smooth.

Next, when the inside of the hydraulic chamber 5 becomes negative pressure and the exhaust valve is closed, the orifice plate 3 is moved from the buffer recess 11.
3 into the hydraulic chamber 5 is large, and most of the pressure oil gradually flows into the hydraulic chamber 5 from the circumferential surface of the adjustment rod 31. Therefore, the impact when the exhaust valve is closed is buffered.

(Effects of the Invention) As explained above, the present invention provides the following effects.

Since the opening operation of the exhaust valve is quick, exhaust is carried out smoothly, the exhaust efficiency is good, and the thermal efficiency of the engine is improved.

There is no shocking closure of the exhaust valve and jumping of the exhaust valve is prevented. This prevents scavenging and supply air from escaping, and in this respect as well, the thermal efficiency of the engine is improved.

Since it is only necessary to provide an orifice plate, the structure is simple and installation is easy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a sectional view showing a conventional hydraulic exhaust valve opening/closing device. 5: Hydraulic chamber, 11: Buffer recess, 31: Adjustment rod,
32: Passage, 33: Orifice board.

Claims (1)

[Claims] 1. A hydraulic piston having a buffer recess at the rod end of the exhaust valve and a hydraulic chamber for applying hydraulic pressure to the hydraulic piston are provided, and an adjustment rod inserted into the buffer recess of the hydraulic piston is used to control when the exhaust valve is closed. In a hydraulic exhaust valve opening/closing device designed to buffer shock, the adjustment rod is provided with a passage that communicates the buffer recess and the hydraulic chamber, and the passage facilitates the flow of pressure oil from the hydraulic chamber to the buffer recess. , a hydraulic exhaust valve opening/closing device comprising a dart pot mechanism that makes it difficult for pressure oil to flow from a buffer recess to a hydraulic chamber, and the dart pot mechanism is composed of an orifice plate having a plurality of lap-like flow passages. Device.