JPH06103014B2 - Dual fuel supply system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for a multi-cylinder internal combustion engine, and more specifically, it uses alcohol or the like, which is difficult to self-ignite by compression, as a main fuel and is excellent in self-ignition by compression. The present invention relates to a dual fuel supply device for a diesel engine that uses light oil or the like as an auxiliary fuel.

[Conventional technology]

It is known that in a multiple fuel supply system that uses alcohol or the like as the main fuel and light oil or the like as the auxiliary fuel, it is preferable to inject them in layers without mixing the alcohol and the light oil. That is, a small amount of light oil is injected first to provide a spark, and then alcohol, which is the main fuel, is injected. Japanese Patent Application Laid-Open No. 58-206867 discloses such a multiple fuel supply device.

[Problems to be solved by the invention]

In the above-mentioned prior art, a fuel injection pump for pumping the main fuel, a pump for pumping the auxiliary fuel, and a fuel injection nozzle are provided, and the pump is one of the main fuel pumped by the fuel injection pump. It is operated by pressure. In order to supply the main and sub fuel in the above-mentioned layered manner, the introduction of the sub fuel into the sub fuel introduction passage of the specific injection nozzle is performed.
This is performed by a pressure feeder operated by the pressure of the main fuel that is being introduced into the main fuel introduction passage of another injection nozzle. Therefore, the specific fuel injection nozzle is filled with the auxiliary fuel prior to the injection timing of the nozzle, and the main fuel is pressure-fed to the nozzle when the turn comes. The sub fuel is filled at a pressure that does not reach the valve opening pressure of the nozzle.

The above-mentioned prior art has a problem that the structure is complicated because the same number of pumps as the number of cylinders is required.
Further, there is a problem in that the filling amount varies between the cylinders due to the manufacturing error of the pressure feeder.

[Means for solving problems]

In order to solve the above problems, according to the present invention, a fuel injection pump having a plurality of discharge ports for pumping a first fuel, a fuel injection nozzle having the same number as the discharge ports, and a second fuel are pumped. And a first fuel introduction passage for introducing the first fuel, and a first fuel introduction passage communicating with the first fuel introduction passage near the injection port. Second fuel introduction passage for introducing two fuels, the first fuel introduction passage of the fuel injection nozzle is connected to the discharge port of the fuel injection pump, and the fuel injection nozzle is also provided. Are divided into two groups, and the second fuel introduction passages of the fuel injection nozzles of each group are commonly connected to one of the pumps, and the fuel injection nozzle is connected to the first fuel injection pump by the fuel injection pump. Only when the pump is pumped An opening means is provided for opening, and each pump is operated by receiving the pressure of the first fuel toward the fuel injection nozzle of the other group, and the second fuel is supplied to the first fuel introduction passage in the first fuel introduction passage. A dual fuel supply device configured to pump at a pressure greater than the residual pressure of the fuel.

〔Example〕

In FIG. 1, the dual fuel supply system according to the present invention comprises one fuel injection pump 10, two pumps 12a and 12b, and fuel injection nozzles 14 as many as the number of cylinders of a diesel engine. In addition, there is a first fuel tank 16 for a main fuel such as alcohol and a second fuel tank 18 for a secondary fuel such as light oil. The fuel injection pump 10 has a feed pump 20
The alcohol fuel is supplied by the feed pump 22, and the light oil fuel is supplied to the pumps 12a and 12b by the feed pump 22 through the branch pipe 24. The fuel injection pump 10 can be constituted by a well-known distributed type or row type fuel injection pump, and has the same number of outlets 26 as the number of cylinders for supplying alcohol fuel to the fuel injection nozzle 14 of each cylinder. A constant pressure delivery valve (not shown) is arranged at each discharge port 26. FIG. 1 shows an example in which the present invention is applied to a four-cylinder internal combustion engine.
There are four discharge ports 26 and four fuel injection nozzles 14, respectively.

Each fuel injection nozzle 14 is composed of a nozzle body 30 having a nozzle orifice 28 at its tip and a needle valve 32 inserted in the nozzle body 30. Although the upper portion of the fuel injection nozzle 14 is omitted in FIG. 1, it will be apparent that a spring for biasing the needle valve 32 is disposed in such an upper portion.

A first fuel introduction passage 34 for introducing a first fuel is formed in the nozzle body 30, and the first fuel introduction passage 34 is a nozzle orifice when the needle valve 32 is opened.
It is possible to communicate with 28. The first fuel introduction passage 34 of each fuel injection nozzle 14 is connected to the discharge port 26 of the fuel injection pump 10 by pipes 36a to 36d, respectively. The pressure of the alcohol fuel pumped from the fuel injection pump 10 acts on the tapered portion 38 of the needle valve 32 to open the needle valve 32. A second fuel introduction passage 40 for introducing light oil fuel is further formed in the nozzle body 30, and the second fuel introduction passage 40 is located near the valve seat of the needle valve 32. Is in communication with. In this embodiment, the second
The fuel introduction passage 40 is formed from the nozzle body 30 through the central portion of the needle valve 32, and radially opens in the annular oil sump portion of the first fuel introduction passage 34 near the tip of the needle valve 32. Further, in the second fuel introduction passage 40, a check valve 42 which allows only the flow toward the nozzle tip portion is arranged. Each fuel injection nozzle 14 has the same structure.

The fuel injection nozzle 14 is divided into two groups. In FIG. 1, the first cylinder and the second cylinder form the first group, and the third cylinder and the fourth cylinder form the second group. Fuel injection nozzle of each group
The 14 second fuel introduction passages 40 are commonly connected to one of the pumps 12a, 12b. That is, the second fuel introduction passages 40 of the fuel injection nozzles 14 of the first and second cylinders are connected to the pipes 44a, 44b,
The second fuel introduction passage 40 of the fuel injection nozzles 14 of the third and fourth cylinders is connected to the pump 12b by a pipe 46c.
It is connected to the pump 12a by a, 46b and 46c. Each pump 12a,
12b is configured to operate by receiving the pressure of the alcohol fuel toward the fuel injection nozzle 14 of the other side group. That is, the pump 12b connected to the fuel injection nozzle 14 of the first group is connected to the pipe 36d directed to the fourth cylinder included in the second group.
12a connected to the branch pipe 48 for receiving the pressure of the alcohol fuel of the second group and connected to the fuel injection nozzle 14 of the second group.
Is connected to the branch pipe 50 so as to receive the pressure of the alcohol fuel of the pipe 36a directed to the first cylinder included in the first group.

Each of the pumps 12a and 12b has a main body 52, and a substantially T-shaped internal cavity is formed in the main body 52, and the internal cavity portion corresponding to the horizontal side of T forms a linear passage, and its end is formed. The parts are an inlet 54 and an outlet 56, respectively. Diesel fuel is supplied to the inlet 54 from the second fuel tank 18 via the feed pump 22. A spring chamber 58 is located in the middle of the T-shape.
Is formed. The internal cavity portion corresponding to the vertical side of the T-shape is a cylinder 62 that slidably supports the pressure-feeding piston 60. The pressure-feeding piston 60 receives the pressure of the alcohol fuel during injection and moves to the right in FIG. 1 to reduce the volume of the passage portion and pressure-feed the light oil fuel from the outlet 56. A spring 64 that pushes back the pressure-feeding piston 60 is arranged in the spring chamber 58. or,
A check valve 66 that allows only the introduction of light oil fuel is arranged near the inlet 54, and a check valve that allows only the discharge of light oil fuel is arranged near the outlet 56.

Next, the operation will be described with reference to FIG.

It is assumed that the injection order is the first, third, fourth, and second cylinders, and as shown by A, the alcohol fuel of the first cylinder is injected at a crank angle of 0 degree. At this time, the pump 12a is branched from the pipe 36a.
The injection piston 60 moves forward in response to the injection pressure of the alcohol fuel via 50, whereby the light oil fuel is supplied to the fuel injection nozzles of the third cylinder and the fourth cylinder as indicated by B and C, respectively.
It is pressure fed to the second fuel introduction passage 40 of 14. Pump 12a, 12b
Is lower than the valve opening pressure of the needle valve 32 of the fuel injection nozzle 14 and the pipes 36a to 3a for supplying alcohol fuel.
It is set to be higher than the residual pressure of 6d. Therefore, the light oil fuel introduced into the second fuel introduction passage 40 pushes away the alcohol fuel near the seat portion of the fuel injection nozzle 14 and enters the first fuel introduction passage 34. That is,
Light oil fuel is filled near the bottom of the first fuel introduction passage 34, and alcohol fuel is present above it.

Next, as shown by B in FIG. 2, when the injection timing of the third cylinder comes, alcohol fuel is supplied from the fuel injection pump 10 to the third position.
It is pressure-fed to the first fuel introduction passage 34 of the fuel injection nozzle 14 of the cylinder, and the needle valve 32 is opened by this pressure-feeding pressure to inject from the nozzle orifice 28. At this time, since there is the check valve 42, there is no backflow in the second fuel introduction passage 40, and the light oil fuel filled at the tip of the first fuel introduction passage 34 is first injected as shown by B. Therefore, the self-ignition can be easily performed, and the subsequently injected alcohol fuel can be surely ignited. Further, the injection is similarly performed during the injection time of the fourth cylinder.

At the time of injection in the fourth cylinder, the other side pump 12b operates, and the tip portions of the fuel injection nozzles 14 of the first and second cylinders as shown by F and G in FIG. Is filled with light oil. Then, the injection is performed at the injection timings of the second cylinder and the first cylinder as indicated by H and J, respectively, and the light oil fuel is also injected first and easily self-ignites. It can ignite surely. In this way, the filling of the light oil fuel and the injection of the alcohol fuel are performed in order.

FIG. 3 shows an example in which the present invention is applied to a 6-cylinder internal combustion engine. Therefore, the fuel injection pump 10 has six discharge ports 26 and six fuel injection nozzles 14, respectively. The structure of the fuel injection pump 10, the pumps 12a and 12b, and the fuel injection nozzle 14 as a single unit is the first.
It is similar to that shown in the figure. In FIG.
The fuel injection nozzles 14 of the two and four cylinders form a first group, each second fuel introduction passage 40 is connected to one of the pressure-feeding cylinders 12b, and the pressure-feeder 12b is a second group of the sixth cylinders. Is configured to receive the injection pressure of the alcohol fuel. The fuel injection nozzles 14 of the third, fifth, and sixth cylinders form a second group, each second fuel introduction passage 40 is connected to the other pressure feeder 12a, and the pressure feeder 12a is It is configured to receive the injection pressure of the alcohol fuel of the cylinder. Therefore, as shown in FIG. 4, all fuel injection nozzles 14 of the second group are filled with light oil fuel at the time of injection of the first cylinder, and all fuel injection nozzles of the first group at the time of injection of the sixth cylinder.
14 can be filled with diesel fuel.

〔The invention's effect〕

As described above, according to the present invention, it is possible to stratify and inject different kinds of fuel from the fuel injection nozzles of all the cylinders by using one fuel injection pump and two pressure feeders. May have an extremely simple structure that operates by receiving the injection pressure of the main fuel, and it is possible to supply the auxiliary fuel on average to a plurality of fuel injection nozzles commonly connected by such a simple pump. Therefore, the variation between the cylinders can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a multiple fuel supply system according to the present invention, FIG. 2 is a diagram for explaining the operation of the system of FIG. 1, FIG. 3 is a diagram showing a second embodiment of the present invention, and FIG. The figure is a view for explaining the operation of the apparatus of FIG. 10 ... Fuel injection pump, 12a, 12b ... Pump, 14 ... Fuel injection nozzle, 60 ... Pump piston, 34, 40 ... Fuel introduction passage.

Claims (1)

[Claims] 1. A fuel injection pump having a plurality of discharge ports for pumping a first fuel, fuel injection nozzles having the same number as the discharge ports, and two pumps for pumping a second fuel. Each of the fuel injection nozzles introduces a first fuel introducing passage for introducing a first fuel and a second fuel communicating with the first fuel introducing passage in the vicinity of the injection port. A second fuel introduction passage, the first fuel introduction passage of the fuel injection nozzle is connected to the discharge port of the fuel injection pump, and the fuel injection nozzle is divided into two groups. The second of the group of fuel injection nozzles
A fuel introduction passage is commonly connected to one of the pumps, and the fuel injection nozzle has opening means for opening the injection port only when the first fuel is pumped by the fuel injection pump, Each pump operates by receiving the pressure of the first fuel toward the fuel injection nozzle of the other group, and operates the second fuel to a pressure larger than the residual pressure of the first fuel in the first fuel introduction passage. A multiple fuel supply device configured to be pressure-fed.