JP5984872B2 - Fuel supply device - Google Patents

Description

  The present invention relates to a fuel pump for a small engine such as a motorcycle, an outboard motor, and a general-purpose engine. In particular, the fuel supply device is configured as a part of an electronically controlled fuel injection system and pressurizes fuel to be sent to an injector. It is about.

  Motorcycles and outboard motors have stricter layout restrictions than four-wheeled vehicles, and may not be able to install a mainstream in-tank fuel supply system in four-wheeled vehicles. In such a case, an in-line fuel supply apparatus that can be mounted in a pipe between the fuel tank and the engine and has a high degree of freedom in layout is used.

  Many in-line fuel supply devices have a suction passage, a discharge passage, and a vapor discharge passage as means for avoiding a decrease in the discharge flow rate, and the fuel supply device is installed at a position lower than the fuel tank. Thus, fuel is supplied into the fuel supply device using the pressure generated by the difference in position head, and the vapor generated in the fuel supply device is discharged from the vapor discharge passage to the upper fuel tank. Yes. The vapor discharge passage is connected to a position higher than the liquid level in the fuel tank by piping in order to prevent fuel from flowing from the fuel tank into the fuel supply device.

A conventional example of the above-described inline fuel supply apparatus will be described below.
The fuel supply device of Patent Document 1 is installed below the fuel tank, is connected to the suction passage through a filter installed in the fuel tank, and sends fuel from the discharge passage to the injector. The vapor discharge passage is connected to a pipe penetrating to a position higher than the liquid level in the fuel tank.

Japanese Patent No. 3896658

However, in the fuel supply device of Patent Document 1 described above, when the pressure loss when the fuel passes through the filter increases due to foreign matter accumulating on the filter in the fuel tank, the fuel is supplied from the fuel tank to the fuel supply device. Accordingly, the liquid level in the pipe connecting the vapor discharge passage and the fuel tank is lowered. Furthermore, when the pressure loss of the filter increases and the liquid level in the vapor discharge passage reaches the inside of the fuel supply device, there is a problem that air is sucked and the discharge flow rate is reduced.
The present invention has been made in view of the above, and provides a fuel supply device that maintains stable fuel suction and prevents a decrease in discharge flow rate even when the resistance on the suction side upstream of the fuel supply device increases. For the purpose.

A fuel supply apparatus according to the present invention is a fuel supply apparatus that is attached to a fuel tank and supplies fuel in the fuel tank to an engine, and has a filter and a suction passage for sucking fuel from the fuel tank, and the fuel supply A discharge passage for discharging fuel pressurized by the device, a vapor discharge passage for allowing vapor generated in the fuel supply device to escape to the fuel tank, and a space between the vapor discharge passage and the fuel tank. A one-way valve for opening and closing the vapor discharge passage, wherein the one-way valve is a ball valve floating in the fuel in the vapor discharge passage and a seat surface on which the ball valve is seated without reaching the inside of the fuel supply device And the position head from the fuel tank liquid level to the seat surface of the one-way valve is larger than the pressure loss head at the time of suction of the filter. In this case, the one-way valve opens away from the seat surface due to buoyancy received from the fuel, and the pressure loss head during suction of the filter is more than the position head from the fuel tank liquid level to the seat surface of the one-way valve. If the pressure increases, the liquid level of the vapor discharge passage is lowered from the seat surface and exposed to the air, and the ball valve is pressed against the seat surface by gravity to close .

  According to the fuel supply device of the present invention, since the one-way valve that opens and closes using the buoyancy in the fuel is provided in the vapor discharge passage, the resistance on the intake side of the fuel supply device is large due to clogging of the filter or the like. Even in this case, since air is not sucked into the fuel supply device from the vapor discharge passage, it is possible to prevent a decrease in the discharge flow rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a simplified diagram illustrating a fuel supply apparatus according to Embodiment 1 of the present invention, where (a) is a diagram illustrating a normal state, and (b) is a diagram illustrating a state when a one-way valve is operating. FIG. 6 is an explanatory diagram of a one-way valve of a fuel supply device according to Embodiment 2 of the present invention, where (a) is a structural diagram in which a ball valve 133A is employed, and (b) is a structural diagram in which a plate-like valve 133B is employed. It is. It is sectional drawing which shows the inside of the fuel pump of the fuel supply apparatus in Embodiment 3 of this invention. The fuel supply apparatus of the conventional fuel system is shown, (a) is a simplified diagram showing a normal state, and (b) is a simplified diagram showing a filter failure state.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In addition, the same code | symbol shows the same or an equivalent part between each figure.

First, a conventional fuel system will be described with reference to FIG.
In FIG. 4, the fuel flows from the fuel tank 101 through the filter 102 into the intake passage 111 of the fuel supply device 103, and after being made high pressure by a fuel pump (not shown) of the fuel supply device 103, the discharge passage 112. And supplied to the injector 104.
The vapor generated inside the fuel supply device 103 at the time of high temperature is discharged from the vapor discharge passage 113 to the upper fuel tank 101.

When the heads on the suction passage side and the vapor discharge passage side are expressed by Bernoulli's equation, the following relationship is established.
H1-ΔP1 / ρg = H2
H2 = H1-ΔP1 / ρg
H1: Height from the fuel supply device 103 to the fuel tank 101 (intake passage side)
Position head)
ΔP1: Pressure loss of the filter 102
H2: liquid level in the pipe between the vapor discharge passage 113 and the fuel tank 101
(Position head on the vapor discharge passage side)
ρ: Specific gravity of fuel

In the above equation, as shown in FIG. 4A, when the pressure loss ΔP1 of the filter 102 is small and the relationship of H1> ΔP1 / ρg (pressure head) is satisfied, H2> 0, and the vapor discharge passage 113 to the fuel A constant liquid level can be secured in the piping between the tanks 101.
That is, the inside of the fuel supply device 103 is filled with fuel.

As shown in FIG. 4B, the pressure loss ΔP1 of the filter 102 increases due to foreign matter accumulating on the filter 102, and H2 = 0 when H1 = ΔP1 / ρg.
That is, the liquid level between the vapor discharge passage 113 and the fuel tank 101 reaches the inside of the fuel supply device 103, and air is sucked from a pipe connecting the vapor discharge passage 113 and the fuel tank 101 to reduce the discharge flow rate. Will occur.

Embodiment 1 FIG.
FIG. 1 is a simplified diagram showing a fuel supply apparatus according to Embodiment 1 of the present invention, where (a) is a diagram showing a normal state, and (b) is a diagram showing a state when a one-way valve is operated. is there.
The flow of fuel supply from the fuel tank 101 to the fuel supply device 103 is the same as that of the conventional fuel system described above. However, in the first embodiment, there is no fuel between the vapor discharge passage 113 and the fuel tank 101. A one-way valve 114 that opens due to the buoyancy of the fuel, that is, a one-way valve 114 that opens and closes the vapor discharge passage 113 using buoyancy caused by fuel is provided.
The one-way valve 114 includes a ball valve 133 having an apparent density smaller than the specific gravity of the fuel and the seat surface 125. When the ball valve 133 is in the fuel, the one-way valve 114 is separated from the seat surface 125 by buoyancy received from the fuel. When the ball valve 133 is in the air, the valve is pressed against the seat surface 125 by gravity to close the valve.
When the heads on the suction passage 111 side and the vapor discharge passage 113 side in the first embodiment are expressed by Bernoulli's equation, the following relationship is established.

H1−ΔP1 / ρg = H3−ΔP3 / ρg
H3 = H1-ΔP1 / ρg + ΔP3 / ρg
H1: Height from the fuel supply device 103 to the fuel tank 101 (position on the suction passage side)
head)
ΔP1: Pressure loss of filter 102 H3: Liquid level height in the pipe between the vapor discharge passage 113 and the fuel tank 101 (vapor)
Position head on the discharge passage side)
ΔP3: Pressure loss of one-way valve 114 ρ: Specific gravity of fuel

As shown in FIG. 1A, when the pressure loss ΔP1 of the filter 102 is small, the relationship of H1> ΔP1 / ρg is established as in the conventional fuel system, and H2> 0. A constant liquid level can be secured in the piping between the fuel tanks 101.
That is, the one-way valve 114 is at a position in the fuel below the liquid level, and the ball valve 133 in the one-way valve 114 has an apparent density smaller than the specific gravity of the fuel, and therefore floats in the fuel and floats on the seat surface 125. And the one-way valve 114 is opened. At this time, the pressure loss ΔP3 when the fuel passes through the one-way valve 114 is substantially 0, and the discharge of the vapor generated in the fuel supply device 103 does not deteriorate.

As shown in FIG. 1B, when the pressure loss ΔP1 of the filter increases due to foreign matter accumulating on the filter 102, H3 decreases toward 0 as in the conventional fuel system.
That is, the liquid level between the vapor discharge passage 113 and the fuel tank 101 decreases toward the inside of the fuel supply device 103. Here, when the liquid level between the vapor discharge passage 113 and the fuel tank 101 is lower than the seat surface of the one-way valve 114, the ball valve 133 in the one-way valve 114 loses buoyancy and is pressed against the seat surface 125. Since the one-way valve 114 is closed, ΔP3 increases rapidly, and as a result, H3 does not decrease any more.
That is, the liquid level between the vapor discharge passage 113 and the fuel tank 101 does not reach the inside of the fuel supply device 103, and air is not sucked from the pipe connecting the vapor discharge passage 113 and the fuel tank 101. Therefore, it is possible to prevent the discharge flow rate from decreasing.

Embodiment 2. FIG.
2A and 2B are explanatory views of a one-way valve of a fuel supply device according to Embodiment 2 of the present invention, in which FIG. 2A is a structural diagram in which a ball valve 133A is employed, and FIG. It is a structural diagram in which the valve 133B is employed. Since the contents other than those described below are the same as those in the first embodiment, description thereof will be omitted.
A ball valve 133A is adopted as the one-way valve 114a shown in FIG. 2 (a), and the seat surface 125 and the ball valve 133A installed between the vapor discharge passage 113 and the fuel tank 101 constitute an on-off valve. Reference numeral 126 denotes a ball jump-out preventing plate.

A modified one-way valve 114b shown in FIG. 2B has a structure in which a plate-shaped valve 133B is employed, one side is supported and fixed by a support shaft 133S, and the free end side is opened by buoyancy in fuel. It is installed between the vapor discharge passage 113 and the fuel tank 101. In the case of this modification, a structure for fixing the one-way valve 114b and a structure for sealing the end face of the case 124 when the one-way valve 114b is closed are necessary.
When the two are compared, the one-way valve 114a shown in FIG. 2A only constitutes the seat surface 125 on which the ball valve 133A is seated in the case 124 that houses the ball valve 133A. The structure can be simplified compared to the above.

Embodiment 3 FIG.
FIG. 3 is a cross-sectional view showing the inside of the fuel pump of the fuel supply apparatus according to Embodiment 3 of the present invention. Since the contents other than those described below are the same as those in the first embodiment, description thereof will be omitted.

  3 is a swash plate piston type pump that sucks and pressurizes fuel by rotating a shaft 116 by a motor unit 115 and converting it into a reciprocating motion of a piston 118 by a swash plate 117 connected to the shaft 116. is there.

  The fuel supply device of FIG. 3 has three of a suction passage 111, a discharge passage 112, and a vapor discharge passage 113, and the ball valve for preventing air suction described in FIG. 2A of the second embodiment. 123 is installed in the pipe of the vapor discharge passage 113. This configuration eliminates the need for installing the one-way valve 114 between the vapor discharge passage 113 and the fuel tank 101, eliminates the need for piping for connecting the one-way valve 114, and reduces the size of the fuel system. It becomes possible.

  In the present invention, each embodiment can be appropriately modified or omitted within the scope of the invention.

101: Fuel tank, 102: Filter, 103: Fuel supply device,
104: Injector, 111: Suction passage, 112: Discharge passage,
113: Vapor discharge passage, 114: One-way valve, 114a: One-way valve,
114b: One-way valve, 115: Motor part, 116: Shaft, 117: Swash plate,
118: Piston, 119: Cylinder, 120: Suction valve, 121: Plate,
122: Discharge valve, 123: Ball valve, 133: Ball valve, 133A: Ball valve,
133B: Plate valve, 124: Case, 125: Seat surface,
126: A ball jump-out preventing plate.

Claims (2)

A fuel supply device that is attached to a fuel tank and supplies the fuel in the fuel tank to the engine. The fuel supply device has a filter and a suction passage that sucks fuel from the fuel tank, and discharges fuel pressurized by the fuel supply device. A discharge passage for discharging the vapor generated in the fuel supply device to the fuel tank, and a one-way opening and closing of the vapor discharge passage provided between the vapor discharge passage and the fuel tank. With a valve,
The one-way valve is composed of a ball valve floating in the fuel in the vapor discharge passage and a seat surface on which the ball valve is seated without reaching the inside of the fuel supply device, and a pressure during suction of the filter When the position head from the liquid level of the fuel tank to the seat surface of the one-way valve is larger than the loss head, the one-way valve opens away from the seat surface by the buoyancy received from the fuel, and the suction of the filter When the pressure loss head at the time becomes larger than the position head from the liquid level of the fuel tank to the seat surface of the one-way valve, the liquid level of the vapor discharge passage falls below the seat surface and is exposed to the air. A fuel supply device, wherein the valve is pressed against the seat surface by gravity to close . 2. The fuel supply apparatus according to claim 1 , wherein the one-way valve is configured by a ball valve or a plate-like valve having an apparent density smaller than that of the fuel.

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