JPS60159386A - Fuel pump - Google Patents

Abstract

PURPOSE:To obtain a simple fuel pump at a low cost by feeding only liquid fuel into a carburetor by installing a float valve into a pump chamber and returning vapor into a fuel return circuit. CONSTITUTION:A float valve 8 is installed into the pump chamber 7 on the discharge side of a discharge valve 5 in a diaphragm-pump chamber 29, and a discharge port 28 to a carburetor is formed below the liquid surface, and the valve port 13 of the float valve 8 is formed in the upper part, and vapor is returned into a fuel return circuit from an outlet 20. When the temperature rises and vapor is formed, the liquid surface (a) of the pump chamber 7 lowers, and the float valve 8 is opened, and the vapor is returned.

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.

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

For example, the return method shown in Japanese Patent Application Laid-Open No. 51-29624 is a system in which a return circuit is provided in the fuel pump and a pressure-sensitive valve is used to open and close the return circuit, but a pressure-sensitive valve with a complicated structure is separately provided. Since it is installed in the fuel pump and connected to the fuel pump via piping, the response is not accurate and it is impractical.

OBJECT OF THE INVENTION The present invention addresses these conventional drawbacks.
The purpose is to perform gas-liquid separation of a gas-liquid mixture inside the pump chamber at high temperatures, and to use the vertical change of the gas-liquid separation interface to open and close the valve port to the return circuit using a float valve. The object of the present invention is to provide a fuel pump of this type that can accurately respond, quickly release vapor components, and send only liquid components from a discharge port to a carburetor.

Accordingly, in the present invention, in a fuel pump in which a suction valve and a discharge valve are alternately opened and closed by the reciprocating motion of a diaphragm to deliver a fixed amount of fuel, the gas-liquid mixture sent by pushing open the discharge valve is heated to a high temperature. A float valve that opens and closes the valve port in response to vertical changes in the gas-liquid separation boundary surface is installed in the pump chamber, which has an effective volume set to perform gas-liquid separation. It is designed to be connected to the return circuit.

The example diaphragm 1 is an upper case 2 that constitutes the pump body.
The suction valve 4, the discharge valve 5, the suction chamber 6, and the pump chamber 7 are provided on the upper case 2 side.

The float valve 8 opens the fuel accumulated in the pump chamber 7 as the liquid level rises and returns it to the fuel tank.The float valve 8 is configured to open and return the fuel accumulated in the pump chamber 7 to the fuel tank. 11. A valve seat 14 is provided at the upper end of the float arm IO through a valve rod 12 in the middle thereof, and opens and closes the valve port 4 by vertical movement of the float arm. The float arm IO and the valve stem 12 are connected with a slight free movement distance in the vertical direction, and an upwardly U-shaped guide body 1G is interposed in the valve stem mounting portion 15. This guide body 1G is fitted into a cylinder portion 17 formed in the upper part of the upper case 2 and is set to be movable up and down. Try to energize the elasticity that protrudes upward.

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

The drive part of the diaphragm 1 is assembled into the lower case 3 side 6
21 is a push rod directly connected to the diaphragm 1; 22 is a rocker arm provided to swing around a pivot arm;
Each time the rotating cam is rotated and pushed once through the connecting rod 5, it automatically returns to its original position under the force of the spring.

In FIG. 1, reference numeral 27 is a suction port communicating with the suction chamber 6, and vanes are a discharge port through which gasoline from the pump chamber 7 is sent to the carburetor.

The rocker arm 22 swings due to the drive of the operating rotating cam, and the push rod 2
When No. 1 is pulled down, diaphragm No. 1 expands downward, so the diaphragm chamber side becomes negative pressure, and suction valve No. 4
The discharge valve 5 is closed at the same time as it is opened. At this time, fuel gasoline (gas-liquid mixture) is sucked through the suction port n.

Next, when the diaphragm 1 is pushed upward, the diaphragm chamber side is compressed, so the suction valve 4 is closed and the discharge valve 5 is pushed open. Therefore, the fuel on the diaphragm chamber side passes through the discharge valve 5 and accumulates in the pump chamber 7, from which it is pumped to the discharge port 0.

By repeating such movements, fuel gasoline is pumped out in fixed quantities, but at high temperatures, a large amount of vapor is generated, so the amount of gas-liquid mixture sucked is small, and the amount of gas in the pump chamber 7 is reduced. The gas-liquid separation interface (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 space above the boundary surface a escapes from the valve port ratio.
It is returned to the fuel tank via piping. The discharge port is always below the boundary surface, and therefore only liquid gasoline is delivered to the carburetor.

Further, when the temperature is normal, the gas-liquid separation boundary surface a rises, and this is detected by the float valve 8 and the valve opening is closed. 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, this invention sucks in a gas-liquid mixture, separates it in the pump chamber, and sends liquid gasoline through the discharge port to the υ carburetor. Return to the fuel tank by opening the valve,
At normal temperatures, the valve port can be closed to collect vapor and provide a sedative effect.The float valve responds to vertical changes in the gas-liquid separation interface, so the response is accurate. It has the advantage of being quick, easy to configure, 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 L... Valve stem 13.
...Valve port 14...Valve sheet applicant Shinryo Electric Manufacturing Co., Ltd.

Claims (1)

[Claims] In a fuel pump that uses the reciprocating motion of a diaphragm to alternately open and close the intake and discharge valves to deliver a fixed amount of fuel, the discharge valve is pushed open to separate the gas-liquid mixture pumped in at high temperatures. A float valve that opens and closes the valve port in response to vertical changes in the gas-liquid separation boundary surface is installed in the pump chamber, which has an effective chamber volume set as such, and the valve port of this float valve is connected to the fuel return circuit. A fuel pump characterized by: