JPH0128285Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a safety device for an internal combustion engine such as a diesel engine that automatically stops the engine when overspeed or a drop in lubricating oil pressure occurs.

In a marine diesel engine, for example, if the hull of the ship runs aground on waves and the propeller is exposed in the air, an overrun occurs in the internal combustion engine.

In addition, in a land diesel engine, for example, when the engine is used to drive a generator, overrun occurs due to failure of the governor or the like.

As described above, diesel engines are equipped with a safety device that can temporarily stop the engine if an overrun occurs.

Furthermore, there is also a safety device that can temporarily stop the engine even if the lubricating oil pressure drops abnormally for some reason.

As shown in Fig. 1, these conventional safety devices operate a solenoid valve Y using an electric signal indicating the occurrence of overspeed detected by a rotary relay X, and supply and drain lubricating oil to an overspeed trip cylinder Z. At the same time, the electric signal of the lubricant pressure drop detected by the pressure switch X' operates the solenoid valve Y' to control the lubricant supply and discharge to the lubricant pressure drop trip cylinder. The engine has been stopped.

The conventional safety devices mentioned above do not function if the power is suddenly cut off, and if the overspeed disappears, the engine stop state is automatically canceled before safety is confirmed, which may cause an unexpected accident. There were problems with certain points.

This invention provides a safety device for an internal combustion engine that solves the above-mentioned problems.It is a completely mechanical safety device, and furthermore, once the engine is stopped due to overspeed occurrence, regardless of whether the overspeed disappears, The feature is that the overspeed trip cylinder cannot be reset unless the reset valve is operated.

Next, the apparatus of this invention will be explained by way of examples with reference to the drawings.

FIG. 2 shows a system diagram of an embodiment of the device of this invention.

In the figure, reference numeral 1 denotes an overspeed trip cylinder, which has a piston 1A and a spring 1B. A linkage (not shown) that controls fuel supply to the engine by pushing up spring 1A against spring 1B.
is ready for fuel supply.

Reference numeral 2 is a pilot valve, which is connected to line A.
The pressure supplied into the pilot pressure oil passage B branched from the pilot pressure oil passage B is kept as pilot pressure and is kept normally open.

A throttle 4 is provided in the pilot pressure oil passage B.
Furthermore, a check valve 5 disposed in parallel with this throttle 4
A line C is connected between the line A and the pilot pressure oil passage B.

Reference numeral 6 designates a normally open reset valve, which is provided in a line E connecting a line D connecting the pilot valve 2 and the overspeed trip cylinder 1 with the pilot pressure oil passage B. There is.

On the other hand, an overspeed trip device 9 is connected to the line A on the downstream side of the check valve 8.

The overspeed trip device 9 is normally closed, and opens upon detecting the occurrence of engine overspeed.
Pressurized oil in line A is discharged into the engine room (not shown).

A line F is connected to the lubricating oil pipe 3 on the upstream side of the throttle 7 of the line A.

Line F is the lubrication oil pressure lowering trip cylinder 10
A normally open pilot valve 11 is provided, which is a line for supplying lubricating oil to the lubricating oil pressure.

The lubricant oil pressure lowering trip cylinder 10 has a piston 10A and a spring 10B. When the lubricant oil pressure exceeds a predetermined value, the piston 10A is pushed up against the spring 10B, and a link (not shown) that controls the fuel supply to the engine is activated. (not) in a state where fuel can be supplied, but
When the lubricating oil pressure decreases, the piston 10A is lowered to stop the engine.

Note that the pilot valve 11 is provided to speed up the lubricating oil pressure supply and discharge operation in the lubricating oil pressure lowering trip cylinder 10, so it may be omitted.

In the device of this invention having the above-mentioned configuration, the illustrated normal state is a state in which neither overspeed nor decrease in lubricating oil pressure occurs.

That is, the pressure oil flowing through the lubricating oil pipe 3 enters the line A having the throttle 7 and the check valve 8, and is supplied from the pilot valve 2 to the overspeed trip cylinder 1 via the line D, causing the piston 1A to resist the spring 1B. It is pushing up.

Further, the pressure oil entering the line F from the lubricating oil pipe 3 is supplied to the lubricating oil pressure reducing trip cylinder 10, and pushes up the piston 10A against the spring 10B.

The normal state of the pilot valve 2 is maintained by normal pilot pressure being supplied from line A through pilot pressure oil path B.

Next, if overspeed occurs due to some reason, this is detected and the overspeed trip device 9 opens, so the pressure oil in line A is released into the engine room and flows into the pilot pressure oil path B. pressure decreases.

When the pilot valve 2 switches due to a decrease in pilot pressure, the pressure oil in the overspeed trip cylinder 1 is released through line D, and at the same time, the supply of pressure oil through line A is cut off, so that the piston 1A is pushed down by the spring 1B, the fuel supply is cut off, and the engine is stopped.

In this state, the amount of pressure oil supplied to the pilot pressure oil path B is kept extremely small by the throttle 4 and check valve 5.
This is maintained continuously by the fact that the rate of pressure release is significantly greater than the pressure increase that allows the pilot valve 2 to return to its old state.

To start the engine again, operate the reset valve 6 and close the line E.

When line E is closed, the pressure in pilot pressure oil passage B gradually rises, and eventually pilot valve 2 switches to a normal state and lubricating oil is supplied to overspeed trip cylinder 1. , it becomes possible to supply fuel to the engine.

As is clear from the above explanation, the device of this invention is safe because once overspeed occurs and the engine is stopped, the engine will not be able to start unless the reset valve is operated.
This system has excellent advantages such as being able to determine at a glance whether the engine has stopped due to a drop in lubricating oil pressure or whether the engine has stopped due to overspeed.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a conventional device, and FIG. 2 is a system diagram showing an embodiment of the device of this invention. In the drawing, A, C, D, E, F... Line, B... Pilot pressure oil path, 1... Overspeed trip cylinder, 2
...Pilot valve, 3...Lubricating oil pipe, 4,7
... Throttle, 5, 8 ... Check valve, 9 ... Overspeed trip device, 10 ... Lubricating oil pressure reduction trip cylinder, 11 ... Pilot valve.

Claims (1)

[Scope of utility model registration request] A pilot valve 2 that can automatically switch the supply and discharge of operating pressure to the overspeed trip cylinder 1 that can freely stop the engine, a line A that connects a lubricating oil pipe 3 to the pilot valve 2, and a throttle 4 that connects this line A. A pilot pressure oil path B to the pilot valve 2 branched through the and parallel to the throttle 4,
In addition, line C is equipped with a check valve 5 that allows oil to flow only in the direction of line A from pilot pressure oil path B.
, a line E connecting the pilot pressure oil passage B to a line D communicating the overspeed trip cylinder 1 with the pilot valve 2, a normally open reset valve 6 provided in the line E, and a reset valve 6 provided in the line E. Restriction 7 installed near lubricating oil pipe 3 in line A
, a check valve 8 provided in line A downstream of this throttle 7, and a normally closed overspeed trip device 9 connected to line A downstream of this check valve 8 and opened when overspeed occurs; A safety device for an internal combustion engine comprising, in addition to the line A, a line F in which a lubricating oil pipe 3 is connected to a lubricating oil pressure reducing trip cylinder 10.