JPH06100159B2 - 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.

[Prior Art] It is known that in a multi-fuel supply device that uses alcohol or the like as a main fuel and light oil or the like as a sub fuel, it is preferable to inject alcohol and light oil in layers without mixing them. . 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. JP-A-58-206859 and JP-A-58-2068
Japanese Patent Publication No. 67 discloses such a dual fuel supply device.

[Problems to be solved by the invention]

In the above-mentioned prior art, a distribution type 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 a pump for pumping the fuel of the distribution fuel pump. It is designed to be operated by the pressure of the main fuel. In order to supply the main / sub fuel in the above-mentioned layered manner, the introduction of the sub fuel into the sub fuel introduction passage of the constant injection nozzle is controlled by the pressure of the main fuel being introduced into the main fuel introduction passage of another injection nozzle. It is designed to be operated by a pump that is operated. Therefore, the auxiliary fuel is introduced into the specific fuel injection nozzle prior to the injection timing of the nozzle,
When the turn comes, the main fuel is injected into the nozzle.
The sub fuel is introduced 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 plunger reciprocating while rotating, a pressure chamber formed by the tip of the plunger, and a distribution passage formed by the number of cylinders around the plunger. And a distribution type fuel injection pump configured to sequentially discharge the first fuel in the pressure chamber pressurized by the plunger from each distribution passage,
A distribution type fuel injection pump is provided with a pressure transmitter that is driven by the pressure of the first fuel in the pressure chamber to deliver the second fuel every time the first fuel in the pressure chamber is pressurized, and is provided in each cylinder. The fuel injection nozzle that communicates with the needle valve that controls the opening and closing of the nozzle orifice, the first fuel introduction passage formed around the needle valve, and the deepest portion on the nozzle orifice side of the first fuel introduction passage. 2 fuel introduction passages,
The first fuel introduction passage of each fuel injection nozzle is connected to the corresponding distribution passage, and the second fuel introduction passage of all fuel injection nozzles is connected to the pressure feeder, and the needle is closed when the needle is closed. Filling the innermost part of the first fuel introduction passage with the second fuel sent from the second fuel introduction passage through the second fuel introduction passage,
When the needle opens, the second fuel filled in the innermost portion of the first fuel introduction passage is first injected from the nozzle orifice, and then the first fuel is injected from the nozzle orifice. .

[Embodiment] In FIG. 1, a dual fuel supply system according to the present invention comprises one distribution type fuel injection pump 10, one pump 12 and as many fuel injection nozzles 14 as there are cylinders of a diesel engine. Composed. 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 distributed fuel injection pump 10 has substantially the same basic structure as that of a conventionally known fuel pump, and therefore parts not directly related to the present invention are omitted. It has a feed pump 20 and a cam plate 22 which are driven by a drive shaft (not shown), and the cam plate 22 slides on a roller 24 to reciprocate while rotating with a plunger 26. The plunger 26 is a cylinder 28 provided on the pump body.
It is slidably inserted in the cylinder 28 and the plunger 26.
The pressure chamber 30 is formed by the tip of the. Plunger 26
There is an inhalation group 32 on the outer periphery of the tip of the. The main fuel in the first fuel tank 16 passes from the feed pump 20 through the pump chamber in the pump body and the fuel passage 34, and further into the suction group.
It is sucked into the pressure chamber 30 through 32.

A port 36 extends in the center of the plunger 26, and the port 36 opens toward the inner wall surface of the cylinder by a radial distribution port 38 near its middle portion. A distribution passage 40 for the number of cylinders is formed at a circumferential position around the plunger 26 in the cylinder 28 and the pump main body, and when the distribution port 38 and the specific distribution passage 40 meet, the main fuel is supplied from the distribution passage 40. Is pumped. It is well known that there is a spill port 42 near the rear end portion of the plunger 26, and the spill ring 4 opens the spill port 42 to end the fuel pumping. It is also well known that the spill ring 44 is controlled by an adjusting lever, a governor mechanism, etc., a fuel cut solenoid valve 46 is arranged in the fuel passage 34, and a delivery passage 40 is provided with a delivery valve. A valve 48 is arranged.

The pump 12 comprises a main body 50, and a substantially T-shaped internal cavity is formed in the main body 50. The internal cavity portion corresponding to the horizontal side of T forms a linear passage, and the ends thereof are respectively introduced. mouth
52 and outlet 54. The second fuel is supplied to the inlet 52 from the second fuel tank 18 via the feed pump 56. The internal cavity portion corresponding to the vertical side of the T-shape is a cylinder 60 that slidably supports the pressure piston 58. The pressurizing piston 58 reduces the volume of the passage portion when it moves to the right in FIG. 1 to pump the second fuel.

The body 50 of the pump 12 is screwed onto the body of the injection pump, and the cylinder 60 of the pump 12 opens into the pressure chamber 30 formed by the tip of the plunger 26 of the injection pump. Therefore,
The pressurizing piston 58 receives the pressure of the pressure chamber 30 from the rear side thereof to reduce the volume of the second fuel passage as described above, and the spring 62 arranged around the fuel passage pressurizing piston 58. It is urged toward the pressure chamber 30 side. The pressurizing piston 58 has a collar-shaped bulging portion in the middle thereof so as to come into contact with the stepped shoulder portion of the cylinder 60, and the retracted position of the pressurizing piston 58 is limited. The tip end of the pressure piston 58 can abut the inner wall of the main body 50, and the advance position of the pressure piston 58 is limited. Therefore, the stroke of the pressurizing piston 58 becomes constant, and the amount of second fuel pumped for each stroke becomes constant. A check valve 64 that allows only the introduction of fuel near the inlet 52
Is disposed, and a check valve 66 that permits only fuel delivery is disposed near the delivery port.

Each fuel injection nozzle 14 is composed of a nozzle body 70 having a nozzle orifice 68 at its tip and a needle valve 72 inserted in the nozzle body 70. 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 72 is arranged in such an upper portion.

A first fuel introduction passage 74 for introducing the first fuel is formed in the nozzle body 70, and can communicate with the nozzle orifice 68 when the needle valve 72 is opened. The first fuel introduction passages 74 are each connected by a pipe 76 to a specific distribution passage 40 of the fuel injection pump. Nozzle body 70
Is further formed with a second fuel introduction passage 78 for introducing the second fuel, and this second fuel introduction passage 78 is provided in the first fuel introduction passage 74 near the valve seat of the needle valve 72. It is in communication. In this embodiment, the second fuel introduction passage
78 is formed from the nozzle body 70 through the central portion of the needle valve 72, and radially opens in the annular portion of the first fuel introduction passage 74 near the tip of the needle valve 72. Further, each fuel injection nozzle 14 is provided with a check valve 80 that allows only the flow in the nozzle tip direction. Each fuel injection nozzle 14 has the same structure, and all the second fuel introduction passages 78 are commonly connected to a single outlet 54 of the pressure feeder 12 via a pipe 82.

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

Since the operation of the distribution type fuel injection pump is well known, it will be briefly explained that fuel is sucked into the pressure chamber 30 during one reciprocation of the plunger 26, is pressurized, and comes into contact with the distribution port 38. Sent by pressure. This dual fuel supply system is installed in a 4-cylinder diesel engine, and the injection sequence is I,
III, IV, II, the crank angle is 0 when the first cylinder is injected.
The injection is completed at a pressure P ₄ as shown in FIG. This pressure P ₄ is naturally larger than the valve opening pressure of the fuel injection amount nozzle 14.

At the time of injection in the first cylinder, the pressurizing piston 58 of the pump 12 moves to the right due to the rise in the pressure in the pressure chamber 30 of the injection pump, so that the second fuel is completely injected from the outlet 54 of the pump 12. It is pumped into the nozzle 14. However, at the fuel injection nozzle 14 of the I-th cylinder that is currently injecting, the second fuel cannot proceed because the pressure from the injection pump applied to the first fuel introduction passage 74 is high, and the second fuel is pushed back. Try to. However, because of the check valve 80, there is no backflow from the fuel injection nozzle 14 to the pipe 82, and the second fuel is the second fuel except for the portion that has entered the tip portion of the first fuel introduction passage 74. The second fuel in the inlet passage 78 is maintained therein.

On the other hand, in the remaining three cylinders that are not currently injecting, the second fuel pumped at the pressure P ₁ from the outlet of the pump 12 is evenly distributed in the second fuel introduction passage 78 of the fuel injection valve 14 of each cylinder. Can enter. At this time, since the pressure P ₁ is higher than the residual pressure in the first fuel introduction passage 74, the second fuel displaces the first fuel and reaches the tip portion of the first fuel introduction passage 74. Further, since the pressure P ₁ is lower than the valve opening pressure of the fuel injection nozzle 14, the second fuel that has entered the tip portion of the first fuel introduction passage 74 as described above is maintained there without being injected. .

The amount of the second fuel entering the first fuel introduction passage 74 increases with each injection at each injection nozzle. That is, for example, in the second cylinder, the second fuel is filled with the pressure P ₁ at the time of injection in the first cylinder subsequent to the injection in that cylinder. When the injection in the first cylinder is completed, the pressure in the pressure chamber 30 is exhausted, so the pressurizing piston 58 moves backward, and the internal space of the pump 12 is newly filled with the second fuel. At this time, the pressure in the pipe 82 may be lower than the pressure in the fuel injection nozzle 14, but there is no backflow of fuel in the fuel injection nozzle 14 because of the check valve 80. Then, crank angle 180
When the injection of the third cylinder is performed at a time, the remaining three cylinders are similarly pressure-fed with the pressure P ₁ . In the second cylinder, since the residual pressure in the first fuel introduction passage 74 is low, the amount of the second fuel corresponding to the pressure P ₁ is further filled. Therefore, a total amount equal to the _two pumping pressures P ₂ is filled. Then, when the injection of the fourth cylinder is performed at a crank angle of 360 degrees, a total amount equal to the pressure feeding pressure P ₃ of three times is filled. And
When injecting the second cylinder at a crank angle of 540 degrees,
Of the fuel introduction passage 74 is already filled with the sufficient second fuel, the first fuel is stratified on the upstream side thereof, and the second fuel is first injected at the same time as the injection is started. The first fuel is easily ignited in the compression stroke, and the self-ignited first fuel that is continuously injected is also easily ignited.

〔The invention's effect〕

As described above, according to the present invention, it is possible to inject a plurality of fuels in a layered manner from the fuel injection nozzles of all the cylinders by using one distribution type fuel injection pump and one pump. The structure is simple. Since only one pump is required for all the cylinders, variations among the cylinders are reduced due to manufacturing errors of the pump. Further, since the relatively small amount of the second fuel is filled in (the number of cylinders-1) times and is distributed to the fuel injection nozzles outside the injection timing in each time, the averaged and uniform filling is performed. The amount is obtained. Furthermore, in the embodiment, since the pump body is directly attached to the injection pump, the apparatus can be made compact as a whole.

[Brief description of drawings]

FIG. 1 is a block diagram of a multiple fuel supply system according to the present invention, and FIG. 2 is a diagram for explaining the operation. 10 ... Fuel injection pump, 12 ... Pump, 14 ... Fuel injection nozzle, 26 ... Plunger, 28 ... Cylinder, 30 ... Pressure chamber, 38 ... Distribution port, 40 ... Distribution passage, 58 ... … Pressurizing piston, 74,78 …… Fuel introduction passage.

Claims (1)

[Claims] 1. A plunger is provided which has a plunger reciprocating while rotating, a pressure chamber formed by a tip end portion of the plunger, and a distribution passage formed around the plunger by the number of cylinders. A distribution-type fuel injection pump is provided, which is configured to sequentially discharge the first fuel in the pressure chamber from each distribution passage, and is driven by the pressure of the first fuel in the pressure chamber of the distribution-type fuel injection pump to drive the fuel in the pressure chamber. First
The fuel injection nozzle provided in each cylinder is formed with a needle valve that controls the opening and closing of the nozzle orifice, and is formed around the needle valve. A first fuel introduction passage and a second fuel introduction passage communicating with the innermost portion of the first fuel introduction passage on the nozzle orifice side are provided, and the first fuel introduction passage of each fuel injection nozzle is provided. The second fuel introduced from the pump is connected to the corresponding distribution passage and the second fuel introduction passage of all the fuel injection nozzles is connected to the pump to supply the second fuel discharged from the pump when the needle is closed. Of the first fuel introduction passage through the fuel introduction passage, and when the needle is opened, the second fuel filled in the deepest portion of the first fuel introduction passage is filled with the second fuel. It is first injected from the nozzle orifice and then the first fuel Double fuel supply apparatus that is ejected from the nozzle orifice.