JPS644073B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is used to supply gasoline as fuel to the engine of an automobile or the like in fixed quantities.

Prior Art The vapor lock phenomenon in the fuel supply system of automobiles occurs when the engine room is exposed to high temperatures, especially in the summer, and when the fuel is vaporized, it becomes bubbles and obstructs the flow of the fuel. Various methods have been proposed to prevent this.

A common way to prevent vapor lock when using a fuel pump is to install a return circuit in the pump casing to circulate part of the fuel and cool the fuel pump, but the required fuel pressure on the carb side is generally 0.2 to 0.4 kg. / ^cm2 , so it is necessary to keep the aperture diameter on the return circuit small.

In JP-A No. 51-23801, a return circuit is installed to cool the fuel pump, but the system uses a temperature sensing valve to directly release gasoline vapor from the pump chamber without passing through the discharge chamber. Therefore, the temperature sensing valve has a problem in that it is difficult to set the temperature at which gasoline vapor is generated (for example, because it changes depending on the properties of gasoline).

Further, a separate check valve (relief valve 12), which is the same as that on the discharge side, is required, so that when the pump chamber is closed to steam, the diaphragm 4 descends and does not rise. Therefore, it is mechanically impossible to open the relief valve and release steam when the pump membrane rises to its maximum. There is also the problem that the orifice diameter of the return circuit cannot be increased because the fuel pressure will drop.

In Utility Model Application Publication No. 54-69214, the valve is opened by applying a second diaphragm to the discharge chamber using negative pressure from the negative pressure intake, but the negative pressure at which gasoline vapor is generated is set. It is difficult to do so, and it is necessary to reduce the diameter of the lithium diaphragm.Therefore, there is a problem that when a large amount of vapor is generated, it is not possible to quickly release the vapor.

Purpose of the Invention The present invention addresses such conventional drawbacks.The purpose of the present invention is to perform gas-liquid separation of a gas-liquid mixture in a pump chamber at high temperatures, and to prevent vertical changes in the gas-liquid separation boundary surface. This type of fuel uses a float valve to open and close the valve port to the return circuit to ensure accurate response and quickly release the vapor component, allowing only the liquid component to be sent to the carburetor from the discharge port. The point is to provide a pump.

Means for Solving the Problem In order to solve the above-mentioned technical problem, the present invention provides a membrane-dynamic fuel system that uses a reciprocating motion of a diaphragm to alternately open and close an intake valve and a discharge valve to deliver fuel in fixed amounts. A pump in which the effective volume of the chamber is defined to a certain size and the discharge port is opened below the boundary surface so that the gas-liquid mixture sent by pushing open the discharge valve is stored and the gas-liquid mixture is separated at high temperatures. A chamber is provided, and a float valve device consisting of a float that responds to vertical changes of the gas-liquid separation boundary surface and a float valve that opens and closes a valve opening on the boundary surface in conjunction with the float is provided in the pump chamber, The valve port of this float valve is opened on the separation boundary surface and connected to the fuel return circuit.

Embodiment A diaphragm 1 is integrally attached between an upper case 2 and a lower case 3 that constitute a pump body, and a suction valve 4, a discharge valve 5, a suction chamber 6, and a pump chamber 7 are attached to the upper case. Provided on the second side.

The float valve 8 opens the vapor accumulated in the pump chamber 7 in response to a rise in the liquid level and returns it to the fuel tank.The float valve 8 has a float arm 10 that swings up and down about a support shaft 9 and a float attached to its tip. 11. A valve seat 14 is provided at the upper end of the float arm 10 via a valve rod 12 in the middle thereof, and opens and closes the valve port 13 by vertical movement of the float arm. The float arm 10 and the valve stem 12 are coupled with a slight free movement distance in the vertical direction, and an upwardly U-shaped guide body 16 is interposed in the valve stem mounting portion 15.
This guide body 16 is fitted into a cylinder portion 17 formed in a part of the upper case 2 and is set to be movable up and down.A valve spring 18 is provided between the valve seat 14 and the guide body 16 to prevent the valve seat 14 Try to energize the elasticity that protrudes upward.

A hose joint 19 is provided at the valve port 13,
The outlet 20 is connected to the fuel tank by piping.

The driving part of the diaphragm 1 is assembled into the lower case 3 side. 21 is a push rod directly connected to diaphragm 1;
Reference numeral 22 denotes a rocker arm which is provided to swing about a pivot 23, and is automatically returned by the force of a spring 26 each time it is pushed once through a connecting rod 25 by rotation of a rotating cam 26.

In FIG. 1, 27 is a suction port that communicates with the suction chamber 6, and 28 is a discharge port that sends gasoline from the pump chamber 7 to the carburetor.

Operation When the rocker arm 22 swings by the drive of the rotary cam 24 and pulls down the push rod 21, the diaphragm 1 expands downward, and the diaphragm chamber 29 becomes negative pressure, opening the suction valve 4 and simultaneously opening the discharge valve 5. close. At this time, fuel gasoline (gas-liquid mixture) is sucked through the intake port 27. Next, when the diaphragm 1 is pushed upward, the diaphragm chamber 2
9 is compressed, so the suction valve 4 is closed and the discharge valve 5 is closed.
is pushed open. Therefore, the fuel in the diaphragm chamber 29 passes through the discharge valve 5 and accumulates in the pump chamber 7, from which it is pumped to the discharge port 28.

Fuel gasoline is sent out in fixed quantities by repeating such movements, but at high temperatures, a large amount of vapor is generated, so the amount of gas-liquid mixture sucked is small, and the gas-liquid separation inside the pump chamber 7 occurs. The boundary surface (liquid level) a falls below the normal level. As the float valve 8 opens the valve port 13 in response to the lowering of the boundary surface a, the vapor accumulated in the upper space of the boundary surface a escapes from the valve port 13 and enters the fuel tank via the piping. Will be returned. The discharge port 28 is always open below the boundary surface and therefore delivers only liquid gasoline to the carburetor.

Also, when the temperature is normal, the gas-liquid separation interface a rises, so this is detected by the float valve 8 and the valve port 13
Close. With this return circuit closure, vapor is collected in the pump chamber at normal temperatures to provide a sedative effect.

Effects of the Invention As described above, the present invention provides a membrane-action fuel pump in which the suction valve and the discharge valve are alternately opened and closed by the reciprocating motion of the diaphragm to deliver fuel in fixed quantities. In order to store the gas-liquid mixture and perform gas-liquid separation at high temperatures, a pump chamber with a chamber effective volume of a certain size and a discharge port opened below the boundary surface is provided, and a gas A float valve device consisting of a float that responds to vertical changes of the liquid separation boundary surface and a float valve that opens and closes a valve opening on the boundary surface in conjunction with the float is provided, and the valve opening of this float valve is connected to the separation boundary surface. It opens at the top and is connected to the fuel return circuit. With this configuration, the gas-liquid mixture is sucked in, separated in the pump chamber, and liquid gasoline is sent from the discharge port to the carburetor.
The vapor can be returned to the fuel tank by opening the valve port when the float valve rises when the temperature is abnormally high, and when the temperature is normal, the valve port can be closed to collect the vapor and perform a sedative effect. Rather than constantly circulating a portion of the fuel as in the pump chamber (discharge chamber), when a large amount of gasoline vapor is generated in the pump chamber (discharge chamber), the float valve is opened using a float and the gasoline vapor is released to the fuel tank side, effectively closing the vapor. can be prevented. Further, in the present invention, as mentioned above, the vapor release involves excessive opening and closing, so the diameter of the valve opening to the return circuit can be increased, thereby allowing gasoline vapor to escape more quickly. The float valve performs such a series of actions quickly and accurately in response to changes in the vertical direction of the gas-liquid separation interface in the pump chamber, and has a great practical effect in that it is simple in construction and can be implemented at low cost.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a vertical sectional side view of a fuel pump, and FIG. 2 is an enlarged sectional view of a float valve portion. 1...Diaphragm, 2...Upper case, 3...
...Lower case, 4...Suction valve, 5...Discharge valve, 6
... Suction chamber, 7 ... Pump chamber, 8 ... Float valve, 10 ... Float arm, 11 ... Float, 12 ... Valve rod, 13 ... Valve port, 14 ... Valve seat.

Claims (1)

[Claims] 1. In a membrane motion fuel pump that uses the reciprocating motion of a diaphragm to alternately open and close the suction and discharge valves to deliver fuel in fixed quantities, the gas-liquid mixture that is pumped in when the discharge valve is pushed open is stored and heated to a high temperature. In order to perform gas-liquid separation at times, the effective volume of the chamber is defined to be a certain size, and a pump chamber is provided with a discharge port opening below the boundary surface, and a pump chamber is provided that responds to vertical changes in the gas-liquid separation boundary surface. A float valve device consisting of a float and a float valve that opens and closes a valve opening on the boundary surface in conjunction with the float is provided, and the valve opening of this float valve is opened on the separation boundary surface and connected to the fuel return circuit. A fuel pump characterized by: