JPS6045743B2 - Self-reversing diesel engine brake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake device for a self-reversing diesel engine used in a ship.

FIG. 1 shows a conventional brake system for a self-reversing marine diesel engine.

When attempting to suddenly stop or reverse a moving vessel, the diesel engine is rapidly reversed, but this procedure first cuts off the fuel. Then the engine continues to reverse.
When the change in air pressure inside the cylinder at this time is shown, an acupressure diagram as shown in FIG. 2 is obtained. That is, the piston is repeatedly compressed and expanded, but the amount of work at that time is the area in the figure multiplied by the engine rotation speed and a certain constant, and the braking work during idle rotation is a small value. Note that 1 in the figure indicates brake work. Next, wait until the engine speed drops to an appropriate value (rotational speed at which brake air can be supplied), and then switch the camshaft to the reverse position. After that, when the starting air control valve 1 shown in FIG.
During the upward stroke, for example, from 1200 before top dead center to top dead center, the starting air control valve 6 opens, control air is sent to the top of the starting valve 5, and the starting valve 5 opens to release high-pressure starting air (this brake air) is supplied into the cylinder 3.

Then, as shown in the acupressure diagram in Figure 3, the pressure inside the cylinder rises rapidly because brake air is supplied from near point A, but eventually the cylinder pressure becomes higher than the brake air pressure (B (near the point), the air is pushed back towards the starting air supply source, creating an acupressure line as shown in the figure.

In other words, the work of the brake is the difference between the force that accelerates the engine and the area of the car that acts as a brake, multiplied by the rotational speed and a certain constant, so in this case, there is a very large braking action.
will appear. When the engine stops in this way,
This time, high-pressure brake air acts to push the piston downward from top dead center, which means that the engine is started in reverse.

Subsequently, fuel is supplied, and when the fuel is ignited and the rotational speed increases, the starting air control valve 1 shown in FIG. 1 is closed and the fuel operation begins thereafter. Note that 4 indicates a cylinder cover, and S indicates a starting air supply source. However, the conventional method described above has the following drawbacks. Even if the fuel supply to the diesel engine is cut off and the engine is allowed to idle, depending on the shape of the ship, it may not be possible to reduce the rotational speed to a level at which brake air can be injected. Of course, the rotational speed at which brake air can be injected varies to some extent depending on the design of the brake (starting) device, but for example, in cases where the hull is large compared to the engine, it may take 2 to 4 minutes for the rotational speed to reach the speed at which brake air can be injected. You may have to wait for the water to drop, which increases the time and distance it takes for the ship to stop, which can be extremely dangerous in some cases. The following problems occur when the brake is applied at a rotational speed higher than the brake air input rotational speed.

(1) It is necessary to first switch the camshaft to the backward position,
Switching at too high a rotation speed may damage the camshaft device.

(2) Even if the camshaft is switched and brake air is injected at a high rotational speed, there may be no braking effect as shown in FIG. 4, and instead the vehicle may accelerate in the forward direction.

That is, from around point A, the pressure inside the cylinder increases rapidly due to the supply of brake air, and from around point B, where the pressure becomes higher than the brake air pressure, the air inside the cylinder is pushed back from the starting valve. However, because the rotational speed, that is, the rising speed of the piston is fast, the pressure rises more rapidly than the air in the cylinder can sufficiently escape, and due to the structure of the starting valve, the starting valve closes automatically (near point C), and from then on the pressure becomes extremely high. During the expansion stroke, the exhaust hole opens at point D and the pressure is released, eventually forming a figure-eight loop as shown in the figure and looking at the difference in the areas of + and -, the brake air accelerates the engine in the opposite direction. It is dangerous because it can happen. An object of the present invention is to focus on the above points, and to provide a brake device that can shorten the time it takes for the ship to stop when the engine is reversed. Forces the engine to do negative work on the air inside the cylinder,
It is equipped with a brake valve and an air release valve that shorten the time required for the rotation speed to reach the speed at which brake air can be applied.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is an explanatory diagram showing one embodiment of the brake device according to the present invention.

In the figure, 1 is the starting air control valve, 2 is the piston, 3 is the cylinder, 4 is the cylinder cover, 5 is the starting valve, 6 is the starting air control valve, and 7 is the starting cam, which are the same as those in Figure 1. It is a member.

The starting air control valve 6 is provided in the controlled air passage 13 between the starting air supply source S and the inlet at the top of the valve casing of the starting valve 5, and opens and closes in conjunction with the starting cam 7 to control the starting valve 5. Open and close.

A brake valve 8 is provided upstream of the starting air control valve 6 in the controlled air passage 13, and controls opening and closing of the starting valve 5 via the starting air control valve 6 during idle rotation of the engine.

Reference numeral 9 denotes a blow valve, that is, an atmospheric release valve, which is a starting air passage 14 between the starting air supply source S and the side inlet of the valve housing of the starting valve 5.
The starting air control valve 1 is provided downstream of the starting air control valve 1. Arrow L indicates the atmosphere. Reference numeral 10 denotes a check valve that prevents compressed air from flowing back into the starting air control valve 1.

The operation in the case of the above configuration will be described.

If a ship suddenly tries to stop while underway, the fuel supply to the main engine is first cut off.

Next, when the brake valve 8 is opened, the starting air control valve 6 operates according to the position of the starting cam 7, and normally from near the top dead center of the piston to about 120 degrees (crank angle) after the top dead center. Control air is directed to the top of the starter valve 5 over the course of the process. Then, the starter valve 5 opens during the expansion stroke, and the compressed high-pressure air in the cylinder 3 is released to the atmosphere through the blow valve 9, and the pressure in the cylinder 3 drops rapidly. In other words, an acupressure diagram as shown in FIG. 6 is obtained. In other words, the diesel engine works as a compressor, and the idle rotational speed of the engine decreases rapidly. When the engine rotational speed has decreased to a value at which brake air can be injected, next, switch the camshaft to the reverse shaft position, close the blow valve 9, and open the starting air control valve 1 to use the starting air as brake air to the cylinder 3.
supply within. Thereafter, when the engine starts in reverse and shifts to fuel operation, the starting air control valve 1 is closed. During this time, the brake valve 8 continues to be opened. The above case has the following effects.

The conventional shiatsu diagram during reversal (Fig. 2) and the shiatsu diagram during operation of the pressure relief type brake device according to the present invention (Fig. 2)
As is clear from a comparison with Fig. 6), in the case of the present invention, the brake work is much greater than when the engine is simply idling, and it takes the engine rotational speed to decrease to the rotational speed at which brake air can be injected. Time can be drastically shortened.

FIG. 7 is a diagram showing the results of a rapid reversal test, where solid line a shows the case according to the present invention, dashed line b shows the conventional case, A is the fuel cutoff point, the mouth is the brake system activation point of the present invention, and C is the brake system operating point of the present invention. The brake air input point, n, is the speed at which brake air can be input.

FIG. 8 shows another embodiment according to the invention.

Reference numerals 1 to 8 indicate the same members as in FIG. 5, and 10, 1
1 is a check valve, and 12 is an automatic atmosphere release valve, which are linked so that they are closed when the starting air control valve 1 is open.

In the case of the above configuration, when the starting air control valve 1 is closed, the starting air passage 14 in the portion connected to the starting valve 5 via the automatic atmosphere release valve 12 is open to the atmosphere.

Therefore, if you want to use the brakes during idle rotation, you only need to open the brake valve 8 and guide the starting air to the starting air control valve 6, and then switch the camshaft to reverse rotation at a rotational speed below the rotational speed at which brake air can be supplied. , then open the starting air control valve 1.
The outlet of the automatic atmospheric release valve 12 is closed and high pressure starting air is introduced to the starting valve 5, and the following operating principle is the same as in the conventional case. Table 1 on the next page shows an example of an automatic sequence for controlling each device of this embodiment.

In Fig. 8, the difference from the conventional operation is that the brake valve 8
Therefore, in order to do this automatically, there is a method in which the brake valve 8 is opened only when the following conditions are satisfied: a command for rapid reverse rotation and a fuel cut-off.

The effect is the same as in the embodiment described above.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing a conventional brake device, Figure 2 is a finger pressure diagram during free rotation, Figure 3 is a finger pressure diagram when brake air is input, and Figure 4 is another diagram when brake air is input. 5 is an explanatory diagram showing an embodiment of the brake device according to the present invention, FIG. 6 is a shiatsu diagram when the brake device according to the present invention is activated, and FIG. 7 is a rapid reversal test result. A line diagram showing
FIG. 8 is an explanatory diagram showing another embodiment of the brake device according to the present invention. 1...Starting air control valve, 2...Zeston, 3...Cylinder, 4...Ulinda cover,
5... Starting valve, 6... Starting air control valve, 7... Starting cam, 8... Brake valve, 9
...Blow valve, 10,11...Check valve, 12...Automatic atmosphere release valve, 13,14...
...Air passage.

Claims (1)

[Claims] 1. A brake valve that is installed upstream of the starting air control valve in the controlled air passage between the air supply source and the starting valve and is opened during engine idle until a predetermined rotational speed is reached after fuel cutoff for engine reversal. , the fuel cutoff for engine reversal is provided downstream of the starting air control valve in the starting air passage between the air supply source and the starting valve, and the valve opens during engine idle until the engine reaches a predetermined rotational speed. A brake device for a self-reversing diesel engine, comprising an atmosphere release valve that releases the air into the atmosphere through the starting valve.