JPH0355811Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a fuel supply system for a multi-cylinder internal combustion engine, and more specifically, the present invention relates to a fuel supply system for a multi-cylinder internal combustion engine. The present invention relates to a dual fuel supply system for a diesel engine that uses light oil or the like as an auxiliary fuel.

[Conventional technology]

In a dual fuel supply device that uses alcohol or the like as a main fuel and diesel oil or the like as an auxiliary fuel, it is known that it is preferable to inject alcohol and diesel oil in a layered manner without mixing them. That is, a small amount of light oil is first injected to provide a spark,
Next, alcohol, which is the main fuel, is injected. Such dual fuel supply devices are disclosed in Japanese Patent Application Laid-open Nos. 58-206859 and 58-206867. In this prior art and other fuel supply systems, distribution fuel injection pumps incorporating feed pumps are widely used.

[Problem that the invention attempts to solve]

If such a distributed fuel injection pump is used to operate a dual fuel supply system that uses light oil as the ignition source and alcohol as the main fuel, as described above, a separate feed pump is required to pre-pressurize the light oil supply. Of course, low viscosity alcohol will pass through the fuel injection pump. Conventionally, diesel oil was used to lubricate the bearings of the drive shaft of fuel injection pumps, and there were no lubrication problems.
When alcohol is used, the problem arises that the low lubricity of alcohol causes seizure of the sliding parts, making high-pressure injection of alcohol impossible.

[Means for solving problems]

A fuel supply device according to the present invention includes a fuel injection pump having a rotatably supported drive shaft,
A first feed pump that delivers a first fuel into the fuel injection pump and a second feed pump that delivers a second fuel into the fuel injection pump.
A feed pump is arranged, and both the first and second feed pumps are driven by the drive shaft.

〔Example〕

The figure shows one distribution type fuel injection pump 10,
The same number of pressure feeders 12 as the number of cylinders of the diesel engine,
A multiple fuel supply system is shown that is comprised of the same number of fuel injection nozzles 14 as the number of cylinders. Furthermore, a first fuel tank 1 for main fuel such as alcohol
6 and a second fuel tank 18 for auxiliary fuel such as light oil.

The distribution type fuel injection pump 10 has a basic structure that is almost the same as that of a conventionally known pump, and parts that are not directly related to the present invention will be briefly described first. The injection pump 10 has a cam plate 22 driven by a drive shaft 20, and the cam plate 22 slides on a roller 24 to rotate together with a plunger 26 and reciprocate. The plunger 26 is slidably inserted into a cylinder 28 provided in the pump body, and a pressure chamber 30 is formed by the cylinder 28 and the tip of the plunger 26 . There is a suction group on the outer periphery of the tip of the plunger 26. A port extends through the center of the plunger 26 and opens toward the inner wall of the cylinder near its midpoint via a radial distribution port. cylinder 2
8 and the pump body, distribution passages 32 corresponding to the number of cylinders are formed at circumferential positions around the plunger 26, and when the distribution port of the plunger 26 and a specific distribution passage 32 meet, that distribution passage 32
The main fuel is pumped from the There is a spill port near the rear end of the plunger 26, and the spill ring 3
As is well known, the pumping of fuel ends when the spill port 4 is opened. It is also known that the spill ring 34 is controlled by an adjuster steering lever 36, a governor mechanism 38, etc., and a fuel cut solenoid valve 42 is disposed in a fuel passage 40 communicating with the pressure chamber 30, and each A delivery valve 44 is arranged in the distribution passage 32 . There is also a timer mechanism 45.

According to the invention, two feed pumps 46, 48 are arranged within this fuel injection pump 10.
These two feed pumps 46 and 48 are both driven by the drive shaft 20 described above, and the two feed pumps 46 and 48 are driven by the drive shaft 20.
They are installed parallel to each other with an interval on top of the 0. Each feed pump 46, 48 is composed of a vane pump, and its 90 degree development view is 46
a, 48a.

The first feed pump 46 is a pump for pre-pressurely supplying the first alcohol fuel, and is disposed in the middle part of the injection pump, that is, in a position close to the cam plate 22, etc., and is arranged from the first fuel tank 16 to the first A fuel passage 50 is formed through the feed pump 46 to the pump chamber of the injection pump. This fuel passage 50 also communicates with the governor mechanism 45.

The second feed pump 48 is for pre-pressurized supply of the second light oil fuel, is disposed at the outermost end of the injection pump, that is, at the outer end side of the drive shaft 20, and is arranged at the outermost end of the injection pump, that is, at the outer end side of the drive shaft 20, A fuel passage 52 is formed which passes through the second feed pump 48 and exits again to the outside of the injection pump. A bearing 54 for the drive shaft 20 is formed near the outer end of the drive shaft 20 in the injection pump, and the fuel passage 52 also passes through this bearing 54. Therefore, according to the present invention, the two feed pumps 46 and 48 can be conveniently installed in the injection pump in order to supply two types of fuel under pressure, and the drive shaft 20 of the injection pump 10 can be lubricated. This can be done using light oil.

The outlet of the fuel passage 52 is connected to the inlet 58 of each pumper 12 via a pipe 56. Each pressure feeder 12
The internal cavity portion corresponding to the horizontal side of the T-shape forms a linear passage within the body 60, and the ends thereof are connected to an inlet 58 and an outlet 62, respectively.
It is becoming. A second fuel is supplied to this inlet 58 from the second fuel tank 18 via the second feed pump 48 . An internal hollow portion corresponding to the vertical side of the T-shape serves as a cylinder 66 that slidably supports a pressurizing piston 64. When the pressurizing piston 64 moves to the right in the drawing, it reduces the volume of the passage portion and pumps the second fuel. Contact surfaces for the pressurizing piston 64 are formed on the front and rear sides of the cylinder 66, respectively.
The stroke of the pressurizing piston 64 is made constant. From the back side of the pressurizing piston 64,
The cylinder 66 is connected to the outlet 33a of the distribution passage 32 of the injection pump 10, and the pressurizing piston 64 is connected to the first
Further, a return spring 68 is disposed on the front side of the pressurizing piston 64. A check valve 70 that only allows fuel to be introduced is arranged near the inlet 58, and a check valve 72 that only allows fuel to be sent out is arranged near the outlet 62.

Each fuel injection nozzle 14 includes a nozzle body 76 having a nozzle orifice 74 at its tip, and a needle valve 78 inserted into the nozzle body 76. Although the upper portion of the fuel injection nozzle 14 is omitted in the figure, it will be clear that a spring biasing the needle valve 78 is disposed in such upper portion.

A first fuel introduction passage 80 for introducing the first fuel is formed in the nozzle body 76 and can communicate with the nozzle orifice 74 when the needle valve 78 is opened. This first fuel introduction channel 80 is in each case connected by a pipe 82 to the outlet 33 of a particular distribution channel 32 of the fuel injection pump.
A first second fuel introduction passage 84 for introducing a second fuel is further formed in the nozzle body 76, and this second fuel introduction passage 84 is connected to the needle valve 7.
It communicates with the first fuel introduction passage 80 near the valve seat 8. In this embodiment, the second fuel introduction passage 84 is formed from the nozzle body 76 through the central portion of the needle valve 78 and extends radially into the annular portion of the first fuel introduction passage 80 near the tip of the needle valve 78. It is open to

The dual fuel supply system having the above configuration is characterized by the connection relationship between the fuel injection pump 10, pressure feeder 12, and fuel injection nozzle 14. That is, the first fuel introduction passage 80 of the fuel injection nozzle 14 shown in the figure is connected to the outlet 33 of a particular distribution passage 32 of the fuel injection pump 10 . On the other hand, the second fuel injection nozzle 14
The cylinder 66 of the pressure feeder 12 for pumping the second fuel into the fuel introduction passage 84 is connected to the outlet 33a of a distribution passage different from the particular distribution passage 32. Therefore, the second fuel flows through the injection nozzle 14
During the injection timing of the first fuel, the first fuel is introduced into the injection nozzle 14a by the pressure of the first fuel appearing at the outlet 33a of the distribution passage during injection from another injection nozzle. This introduction pressure is set lower than the valve opening pressure of the fuel injection nozzle 14, and therefore, the introduced second fuel enters near the tip of the first fuel introduction passage 80. Thus, in the first fuel introduction passage 80, there is the second fuel near the tip, followed by the first fuel upstream thereof. The fuel thus introduced in a layered manner is injected at the injection timing of the injection nozzle. As a result, the second light oil fuel injected first can be easily ignited, and the second alcohol fuel injected subsequently can also be easily ignited.

[Effect of idea]

As explained above, according to the present invention, by providing one fuel injection pump with two feed pumps, it is possible to simultaneously prepress two types of fuels with different characteristics without changing the configuration of a conventional fuel injection pump. By supplying one of the fuels to the drive shaft of the fuel injection pump, good lubrication of the drive shaft can be achieved.

[Brief explanation of the drawing]

The figure is a sectional view of an embodiment of the present invention. 10... fuel injection pump, 12... pressure feeder, 1
4... Fuel injection nozzle, 20... Drive shaft, 46,
48...Feed pump.

Claims (1)

[Scope of utility model registration request] A fuel injection pump having a rotatably supported drive shaft is provided, and a first feed pump for delivering a first fuel and a second feed pump for delivering a second fuel are disposed within the fuel injection pump. ,
A fuel supply device characterized in that both the first feed pump and the second feed pump are driven by the drive shaft.