JP2526088Y2 - diesel engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine which plans a high output and performs a proper fuel injection corresponding to a high / low load region.

[0002]

2. Description of the Related Art FIG. 4 shows a device proposed by the present inventors as a means for increasing the output of a conventional diesel engine.

In conventional diesel engines, 1
The fuel was pumped to each injection nozzle by the individual fuel injection pumps.However, when the engine became larger with the shift to higher output of the diesel engine, the fuel injection pump also became larger, resulting in a larger engine. Becomes bulky,
In addition, costs have become higher.

Therefore, in the above proposal, as shown in FIG.
Two fuel injection pumps are provided, and each of these fuel injection pumps 3
By connecting the injection pipes 5a and 3b to each of the injection nozzles 2, the amount of fuel injection from each of the injection nozzles 2 can be increased, and high output can be achieved without increasing the size of the fuel injection pump. I made it.

In FIG. 4, 1 is a diesel engine main body, 4 is a camshaft interlocking mechanism, 9 and 10 are turbochargers, and 11 and 12 are intercoolers.

[0006]

However, even if two such fuel injection pumps are provided, either one of the fuel injection pumps is required to adjust the fuel injection amount when the engine is at high output and at low output. It is necessary to provide the injection pump with a fuel switching mechanism, so that a special type of pump is used. Therefore, there is a problem that the cost is high and it is only one step to achieve the intended purpose sufficiently.

The present invention has been made in view of such a problem, and a switching valve is provided between one of the two fuel injection pumps and each of the injection nozzles to control the switching valve. In addition to sending or not sending fuel to the injection nozzle side, use two or one fuel injection pump to increase or decrease the fuel injection amount to the engine so as to adapt to the high and low load range of the engine Accordingly, an object of the present invention is to provide a diesel engine capable of performing fuel injection adapted to a high and low load range of an engine without using an ordinary fuel injection pump without increasing the size of the entire engine.

[0008]

According to the present invention, there is provided a diesel engine having two fuel injection pumps and connecting each fuel injection pump to an injection nozzle. A fuel tank return pipe is connected to an injection pipe extending from one of the fuel injection pumps to the injection nozzle, and a fuel from the one fuel injection pump is supplied to a branch portion between the injection pipe and the fuel tank return pipe. A switching valve for switching between the injection nozzle side and the fuel tank return pipe side is provided.

According to a second aspect of the present invention, in the diesel engine according to the present invention, the switching valve transfers fuel from the one fuel injection pump to the fuel tank return pipe side in a load region lower than a required engine load. Switching, and in a load region higher than the required engine load, the fuel from the one fuel injection pump is switched to the injection nozzle side.

[0010]

In the diesel engine according to the first aspect of the present invention, the fuel from one of the fuel injection pumps is injected by the switching valve in the middle of the injection pipe from one of the fuel injection pumps to each of the injection nozzles. It is sent to the nozzle side or the fuel tank return side. Note that the fuel from the other fuel injection pump is always sent to the injection nozzle side.

In the diesel engine according to the present invention, when the engine is in a load region lower than a required engine load, fuel from one of the fuel injection pumps is sent to the fuel tank return side, and in a high load region. , The switching valve is switched so as to send to the injection nozzle side.

[0012]

1 to 3 show a diesel engine as one embodiment of the present invention, and FIG. 1 shows an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of such a diesel engine.
Is a schematic configuration diagram showing the configuration around one fuel injection pump in detail, FIG. 3 is a schematic cross-sectional view of the switching valve, and FIGS.
3, the same reference numerals as those in FIG. 4 denote substantially the same parts.

1 and 2, reference numeral 1 denotes an engine body of a diesel engine. The diesel engine body 1 is provided with a plurality of injection nozzles 2 according to the number of cylinders.

Numerals 3a and 3b denote two fuel injection pumps provided vertically, respectively. These fuel injection pumps 3a and 3b are driven by a camshaft interlocking mechanism 4 from the engine body 1. . The same number of injection pipes 5 as the injection nozzles 2 of the engine main body 1 are led out to each of the fuel injection pumps 3a and 3b, and each of them is connected to each of the injection nozzles 2.

By the way, in the middle of each injection pipe 5 from one fuel injection pump 3a to each injection nozzle 2,
Branch portions are formed, and a switching valve 6 is provided at each of the branch portions.

These switching valves 6 are operated by a controller (electronic control unit) 7 which operates by detecting the engine speed and the engine load.

Each switching valve 6 is an electromagnetic three-way valve. As shown in FIG. 3, an example of the switching valve 6 is a port 6a connected to one fuel injection pump (I / P) 3a, and an injection nozzle. A valve 6d is provided with a port 6b connected to the second side and a port 6c connected to the return passage 8 to a fuel tank (not shown), and switches between these ports 6a, 6b, 6c. Is provided. The valve element 6d is operated by a solenoid 6e that is excited or demagnetized by receiving an electric signal a from the controller 7, and one of the fuel injection pumps 3a is operated by the operation of the valve element 6d.
It switches between sending the injected fuel from the nozzle to the injection nozzle 2 side and sending it to the fuel tank return side passage (fuel tank return pipe) 8.

Reference numerals 9 and 10 in FIG. 1 denote two-stage turbochargers, 9a and 10a denote respective compressors, and 9b and 10b denote respective turbines.

Reference numerals 11 and 12 denote intercoolers.

With the above configuration, the fuel supplied from one fuel injection pump 3a is switched by the switching valve 6 between the supply to the injection nozzle 2 and the return to the fuel tank through the fuel tank return side passage 8. Can be Further, since the fuel from the other fuel injection pump 3b is sent only to the injection nozzle 2, the amount of fuel sent to the injection nozzle 2 is changed by switching the switching valve 6 according to a command from the controller 7.
The fuel is fed only from the other fuel injection pump 3b, or the fuel from both the one and the other fuel injection pumps 3a and 3b is sent together to increase or decrease.

In this case, when the switching valve 6 is open to the fuel tank return side passage 8, the value of the passage resistance to the fuel tank is very small, which causes the fuel pressure to rise. And there is almost no drive loss to the fuel injection pump 3a.

Therefore, in the present embodiment, it is not necessary to increase the size of the fuel injection pump or to use a special type with a fuel switching mechanism only by adding small and inexpensive components such as the switching valve 6 and the controller 7. It is possible to suppress an increase in the size and cost of the entire engine.

The switching of the switching valve 6 by the controller 7 is as follows. That is, when the controller 7 determines that the engine is in a lower load range than the required engine load (for example, a load range smaller than 2/4 of the full load) by detecting the engine speed, the engine load, and the like. When the switching valve 6 is switched to the fuel tank return side passage 8 and it is determined that the load is higher than the required engine load (for example, the load is more than 2/4 of the full load), the switching valve 6 is injected with fuel. Switching to the nozzle 2 side is performed.

Therefore, in a low engine load region, only the fuel from the other fuel injection pump 3b is sent to the injection nozzle 2 to perform a small amount of fuel injection. Since both fuels from the fuel injection pump 3b are sent to the injection nozzle 2 to perform a large amount of fuel injection, the fuel injection in each load region is made
There is an effect that high output of the engine can be achieved.

[0025]

As described above in detail, according to the diesel engine of the present invention, the diesel engine is provided with two fuel injection pumps and each fuel injection pump is connected to an injection nozzle. In the above, a fuel tank return pipe is connected to an injection pipe extending from one of the fuel injection pumps to the injection nozzle, and the fuel from one fuel injection pump is supplied to the injection nozzle side at a branch portion between the injection pipe and the fuel tank return pipe. Alternatively, since a switching valve for switching to one of the fuel tank return pipe side is provided, a switching operation of performing fuel injection to the injection nozzle by two fuel injection pumps or one fuel pump is performed. Can be easily performed using small and inexpensive parts such as a switching valve, thereby eliminating the need for a large pump or a special pump, etc. There is an effect that can be suppressed and costs Koka.

In the diesel engine according to the second aspect of the present invention, the switching valve switches the fuel of one of the fuel injection pumps to the fuel tank return pipe side in a load region lower than the required engine load. In a higher load region than the load, the fuel from one of the fuel injection pumps is configured to be switched to the injection nozzle side, so that appropriate fuel injection according to the operating state of the engine can be realized, thereby There is an advantage that it is effective for increasing the output of the engine.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a diesel engine showing an embodiment of the present invention.

FIG. 2 is a schematic structural view showing a main part of one embodiment of the present invention in detail.

FIG. 3 is a schematic sectional view showing an example of a switching valve according to an embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a diesel engine showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine main body 2 Injection nozzle 3a One fuel injection pump 3b The other fuel injection pump 4 Camshaft interlocking mechanism 5 Injection pipe 6 Switching valve 6a Fuel injection pump side port 6b Injection nozzle side port 6c Fuel tank side port 6d Valve body 6e Solenoid 7 Controller 8 Fuel tank return side passage 9,10 Turbocharger 9a, 10a Compressor 9b, 10b Turbine 11,12 Intercooler

Claims (2)

(57) [Scope of request for utility model registration] In a diesel engine having two fuel injection pumps, each of which is connected to an injection nozzle, a fuel tank is returned to an injection pipe extending from one of the fuel injection pumps to the injection nozzle. A pipe is connected, and a switching valve that switches fuel from the one fuel injection pump to either the injection nozzle side or the fuel tank return pipe side is provided at a branch portion between the injection pipe and the fuel tank return pipe. A diesel engine characterized by being provided. 2. The switching valve switches fuel from one of the fuel injection pumps to the fuel tank return pipe side in a load region lower than a required engine load, and switches the fuel from the one fuel injection pump to a load region higher than the required engine load. 2. The diesel engine according to claim 1, wherein the fuel from the one fuel injection pump is switched to the injection nozzle side.