JPH10252595A - Diaphragm type fuel pump having lubricating oil supply port - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify piping by arranging a check valve for preventing inflow of fuel in a lubricating oil supply port opened to a fuel intake chamber in such a manner as to be projected in the intake chamber in a system where lubricating oil measured by a lubricating oil pump is supplied to the fuel intake side of a film type fuel pump in a 2-cycle engine. SOLUTION: A diaphragm type fuel pump 1 for measuring and supplying lubricating oil is so constructed that a pump operating chamber 1-5 and a pulse pressure chamber 1-6 are partitioned by a diaphragm 1-4, an intake side check valve 1-8 is arranged between a fuel intake chamber 1-1 and the pump cooperating chamber 1-5, and a discharge side check valve 1-9 is arranged between the fuel discharge chamber 103 and the pump operating chamber 1-5. In this case, a lubricating oil supply port opened to the fuel intake chamber 1-1 is provided with a check valve 6. The check valve 6 is provided with a part 6-1 projected into the fuel intake chamber 1-1, whereby when foreign matter gets mixed in fuel, foreign matter 10 staying at the bottom of the fuel intake chamber 101 is kept from covering the opeing part of the check value 6 not to enter the inside of the check value 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke engine separate lubrication system in which lubricating oil is metered by a lubricating oil pump separately from fuel, and the measured lubricating oil is supplied to the suction side of a membrane fuel pump. The present invention relates to an improvement of a membrane fuel pump in an object.

[0002]

2. Description of the Related Art In a separate lubrication system of a two-cycle engine, lubricating oil measured by a lubricating oil pump is first dropped into a float chamber of a carburetor. In an engine whose operating conditions change rapidly, such as a cycle engine, the amount of lubricating oil supplied to the engine does not follow sudden changes in operating conditions, and separate lubrication is used to reduce the amount of lubricating oil relative to the amount of fuel. Since one purpose of the system could not be sufficiently satisfied, a method of dropping lubricating oil measured by a lubricating oil pump into an intake pipe or a crankcase of a two-stroke engine was performed.

However, in the method of metering and dropping lubricating oil into an intake pipe or a crankcase, the amount of oil supplied by pulsating intake pressure or blowback changes the planned metered value of the lubricating oil pump. For a two-stroke engine that does not require a sudden change in operating conditions, a method of dropping lubricating oil into the float chamber was used to upset the engine. However, the lubricating oil dropped into the float chamber was not sufficiently stirred with the fuel. However, there is a problem that the lubricating oil is not uniformly supplied to the engine. As shown in FIG. 7, the lubricating oil is supplied directly to the fuel supply pipe for supplying the fuel to the membrane fuel pump or the fuel suction chamber of the membrane fuel pump. A method of supplying lubricating oil, agitating the fuel and the lubricating oil by the pump action of the membrane fuel pump, and supplying the fuel in which the lubricating oil is well mixed to the floater chamber of the carburetor has begun. In this case, the check valve for preventing the lubricating oil from flowing backward or leaking into the fuel while the engine is stopped is arranged in the middle of the lubricating oil supply pipe connected to the discharge side of the lubricating oil pump.

In FIG. 7, a solid line indicates a pipe for supplying lubricating oil to a fuel supply pipe, and a broken line indicates a pipe for directly supplying lubricating oil to a fuel suction chamber of a membrane fuel pump. 2 is a fuel supply pipe, 3 is a lubricating oil pump,
Reference numeral 4 denotes a lubricating oil supply pipe connected to a discharge port of the lubricating oil pump 3, 5 denotes a T-piece connecting the lubricating oil supply pipe 4 to the fuel supply pipe 2, and 6 denotes a check arranged in the middle of the lubricating oil supply pipe 4. valve,
Reference numeral 7 denotes an arrow indicating the flow direction of the fuel, 8 denotes an arrow indicating the flow direction of the lubricating oil, and 9 denotes a clip for tightening a connection portion of the pipe. The method of supplying the lubricating oil to the fuel suction chamber of the membrane fuel pump 1 by a broken line is simpler than the method of connecting the fuel supply pipe 2 to the fuel supply pipe 2.

[0005]

In the method shown in FIG. 7 in which the lubricating oil is supplied to the fuel supply pipe 2 or the fuel suction chamber of the membrane fuel pump 1, the lubricating oil is supplied from the connection point with the fuel supply pipe 2 or the membrane fuel pump 1. There is a case where the fuel diffuses and flows backward in the lubricating oil supply pipe 4 before reaching the check valve 6. This can occur not only during periods of engine shutdown, especially when the flow of lubricating oil is stopped, and can also result in engine seizure due to a delay in the start of lubricating oil supply at the start of engine operation. Fuel pipes that are oil-resistant but not fuel-resistant may swell and fall off from connection points, causing a fire due to fuel leakage.

Further, a check valve 6 is provided in the middle of the lubricating oil supply pipe 4.
The fuel supply pipe 2 and the lubricating oil supply pipe 4
Not only does the piping work at the time of assembling the engine become troublesome, as is the connection with the lubricating oil supply pipe 4 having the same diameter on both the inlet side and the outlet side. The lubrication oil may be installed in the opposite direction to the flow direction.

When lubricating oil is directly supplied to the fuel suction chamber of the membrane fuel pump 1, foreign matter enters the lubricating oil supply pipe 4 from an opening to which the lubricating oil supply pipe 4 is connected, and is clogged. Supply may be obstructed, causing engine seizure.

[0008]

SUMMARY OF THE INVENTION In a two-stroke engine separate lubrication system in which lubricating oil is metered by a lubricating oil pump separately from fuel, the measured lubricating oil is supplied to the fuel suction side of a membrane fuel pump 1. In the supply, the fuel inlet and the lubricating oil supply port are opened in the fuel suction chamber of the membrane fuel pump 1 to prevent the fuel from flowing into the lubricating oil supply pipe at the lubricating oil supply port. The check valve 6 is configured to protrude into the fuel suction chamber.

[0009]

Operation and Effect The lubricating oil supply pipe 4 is connected directly to the fuel suction chamber to simplify the pipe work, and the check valve 6 is further mounted on the fuel pump 1 of the membrane type fuel pump 1 as shown by the broken line in FIG. By changing to the opening of the suction chamber, the work of connecting the two positions of the check valve 6 on the inlet side and the outlet side to the lubricating oil supply pipe 4 is eliminated, so that the pipe work is further simplified.

A check valve 6 is provided at the outlet of the lubricating oil supply pipe 4 to diffuse the fuel in the fuel suction chamber of the membrane fuel pump 1 into the lubricating oil or to supply the lubricating oil with the backflow of the lubricating oil. Since the fuel can be prevented from flowing into the pipe 4, the lubricating oil supply pipe 4 which is oil-resistant and not fuel-resistant is not swelled or damaged by the fuel.

Unlike the case where the check valve 6 is disposed in the middle of the lubricating oil supply pipe 4, there is no possibility that the check valve 6 is erroneously mounted in the direction opposite to the flow direction of the lubricating oil. When the check valve 6 is mounted in the opposite direction, the supply of the lubricating oil is blocked.

Since the check valve 6 is mounted so as to protrude into the fuel suction chamber of the membrane fuel pump 1, the membrane fuel pump 1 is mounted on the engine with the check valve 6 positioned at the lowest position of the fuel suction chamber. Even in such a case, there is no danger that foreign matter may clog the check valve 6 or impair the closing function of the check valve.

The check valve 6 arranged in the fuel suction chamber of the membrane fuel pump also has a function of preventing the lubricating oil from flowing backward during the stoppage of the engine or leaking into the fuel.

[0014]

FIG. 1 is a sectional view showing an example of an embodiment of a membrane fuel pump having a lubricating oil supply port according to the present invention in which a check valve 6 is disposed at a lubricating oil supply port opening to a fuel suction chamber. FIG. 2 is a sectional view taken along the line AA of FIG. 1 and shows only a part of the fuel suction chamber. The purpose of the present invention is to arrange a check valve for lubricating oil in the fuel suction chamber of a membrane fuel pump, and not to the structure of the membrane fuel pump 1 itself. The configuration of the membrane fuel pump shown in FIG. 2 will be schematically described.

1 and 2, reference numeral 1 denotes a membrane fuel pump as described above. 1-1 is a fuel suction chamber, 1-2 is a fuel inlet, and 1-3 is a fuel discharge chamber. 1-4
Is a diaphragm, and the diaphragm 1-4 separates the pump working chamber 1-5 from the pulse pressure chamber 1-6. A pulse pressure generated by the engine is guided to the pulse pressure chamber 1-6 through a passage 1-7. A suction check valve 1-8 is provided between the fuel suction chamber 1-1 and the pump action chamber 1-5, and a discharge check valve is provided between the fuel discharge chamber 1-3 and the pump action chamber 1-5. A valve 1-9 is arranged, and the pumping chamber 1-5 is pumped by the pulse pressure acting via the diaphragm 1-4. The fuel outlet opening to the fuel discharge chamber 1-3 is not shown.

Reference numeral 6 denotes a check valve arranged at a lubricating oil supply port opened to the fuel suction chamber 1-1. FIGS. 1 and 2 show a mounting posture for maximizing the performance of the membrane fuel pump 1, that is, the diaphragm 1-4 is in a vertical plane, the suction side check valve 1-8 is at the lowest position, and the discharge side check valve. In a mounting posture in which 1-9 is the uppermost position, a state in which the check valve 6 is disposed at the bottom of the fuel suction chamber 1-1 is shown. 6-1 is a fuel suction chamber 1 of the check valve 6;
1 shows a protruding part. When foreign matter is mixed in the fuel, the foreign matter is removed from the fuel suction chamber 1 through long-term use.
When the check valve 6 is mounted without protruding into the fuel suction chamber 1-1, foreign matter covers the opening of the check valve 6 and enters the inside of the check valve 6. Intrusion and clogging of the openings to prevent the supply of lubricating oil or the check valve 6
There is a possibility that the closing function of the check valve 6 may be impaired due to the fact that the valve body 6-2 of the check valve 6-2 cannot be seated.
Is prevented from accumulating around the protruding portion 6-1 and entering the inside of the check valve 6. 6-3 is a lubricating oil supply pipe 4
(See FIG. 7).

FIG. 3 shows that the fuel suction chamber 1-1 of the membrane fuel pump 1 mounted in the posture of FIGS.
1 shows a state in which the lubricating oil supply port is opened to avoid the bottom and the check valve 6 is arranged. In this case as well, if the check valve 6 is arranged to protrude into the fuel suction chamber 1-1, the engine will Due to the layout of the above, the membrane fuel pump 1 is mounted on the engine in an installation posture which cannot be said to be the best as shown in FIG. 4, so that the check valve 6 is located at the bottom of the fuel suction chamber 1-1. Even if there is, the foreign matter 10 in the fuel accumulates around the check valve 6, there is no possibility that the function of the check valve 6 will be disturbed.

Although the present invention does not aim at the structure of the check valve 6, the structure of the check valve 6 shown in FIGS. 1 to 4 is shown in FIG. This will be described a little further. In FIG. 5, reference numeral 6-4 denotes a valve body 6-2 and a coil spring 6 for urging the valve body 6-2 in a seating direction.
The valve housing 6-4 includes a portion 6-1 projecting into the fuel suction chamber 1-1. 6-6 is a lid including a connection portion 6-3 of the lubricating oil supply pipe 4,
A valve seat 6-7 on which the valve body 6-2 is seated is formed at the inner end. The valve housing 6-4 and the lid 6-6 are connected by press-fitting, and the assembled check valve 6 is a valve housing 6-4.
Is press-fitted into a lubricating oil supply port opened to the fuel suction chamber 1-1 of the membrane fuel pump 1.

FIG. 6 is a sectional view taken along the line BB of FIG.
Is a groove provided on the outer periphery of the valve body 6-2, and forms a lubricating oil flow path between the valve body 6-2 and the inner peripheral surface of the valve housing 6-4 when the valve body 6-2 is separated. FIGS. 5 and 6 show one configuration example of the check valve 6, and the present invention does not limit the check valve 6.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of a membrane fuel pump having a lubricating oil supply port according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a diagram in which a mounting position of a check valve is changed in a mounting state of the membrane fuel pump in FIGS. 1 and 2;

FIG. 4 is a diagram of the membrane fuel pump having the same check valve mounting position as that of FIG.

FIG. 5 is an exploded view showing a configuration example of a check valve.

FIG. 6 is a sectional view taken along a line BB in FIG. 5;

FIG. 7 is a diagram showing an example of a conventional lubricating oil supply pipe for supplying lubricating oil to a fuel suction side of a membrane fuel pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Membrane fuel pump 2 Fuel supply pipe 3 Lubricating oil pump 4 Lubricating oil supply pipe 5 T child 6 Check valve 7 Arrow indicating the direction of flow of fuel 8 Arrow indicating the direction of flow of lubricating oil 9 Clip 10 Foreign matter

Claims (1)

[Claims] A separate lubrication system of a two-cycle engine for supplying lubricating oil separately from fuel by a lubricating oil pump (3), and the measured lubricating oil is supplied to a fuel intake side of a membrane fuel pump (1). A fuel inlet and a lubricating oil supply port are opened in a fuel suction chamber (1-1) of the membrane fuel pump (1), and a lubricating oil supply pipe ( 4) A membrane fuel having a lubricating oil supply port, wherein a check valve (6) for preventing fuel from flowing into the fuel injection chamber (1-1) is disposed so as to protrude into the fuel suction chamber (1-1). pump.