JPH0647675U - Fuel pump - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the amount of fuel supply without increasing the size of the fuel pump. [Structure] Cushion chambers 12 and 13 having one wall formed by diaphragms 12 and 13 are provided upstream of the intake valve 17 and downstream of the discharge valve 18, respectively. The air chambers 14 and 15 are provided behind the diaphragms of the respective cushion chambers, and the partition walls 27 partitioning these air chambers are provided with the ports 28 for shifting the pressures of the respective air chambers to act on each other.
To provide.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fuel pump in which a pump diaphragm is vibrated and a check valve cooperating therewith performs a pumping action.

[0002]

[Prior art]

 Conventionally, in the above-mentioned fuel pump device, a cushion chamber whose one wall is formed by a diaphragm is provided upstream of the intake valve and downstream of the discharge valve, and the action of the cushion chamber aims to increase the fuel supply amount and the pulsation of the discharged fuel. I try to hold down.

[0003]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional one, the discharge amount is determined by the volume of the pump chamber, and in order to increase the discharge amount, it is necessary to increase the volume of the pump chamber, but this increases the size of the pump. However, the size of the fuel pump cannot be increased because the space inside the engine room is small and the mounting space for the fuel pump is limited.

Therefore, an object of the present invention is to increase the fuel supply amount without enlarging the fuel pump.

[0005]

[Technical means for solving problems]

 According to the present invention, a closed air chamber is provided at the back of the diaphragm of each of the suction side and discharge side cushion chambers, and the pressures of the respective air chambers are offset from each other in the partition walls that partition these air chambers. It is characterized in that a port for acting on is provided.

[0006]

[Action]

 The fuel pump is pumped by a vibration of the pump diaphragm and a check valve that operates in cooperation with the vibration. The diaphragm in the cushion chamber vibrates in response to the suction pressure and the discharge pressure of the fuel, reducing the fuel pulsation and increasing the fuel discharge amount.

Further, due to the vibrations of the suction side diaphragm and the discharge side diaphragm, a pulsating pressure is generated in the air chamber at the back of each diaphragm, and the pressure is shifted by a port provided in the partition wall so that the air chambers have a pulsating pressure. The operation of both diaphragms is controlled in accordance with the vibration of the pump diaphragm so that the fuel is sucked and discharged most efficiently.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a pump casing. Inside the casing 1, a first ward chamber 2, a second ward chamber 3 and a third ward chamber 4 are provided. The first ward chamber 2 is provided with a pump diaphragm 5 and a pump chamber 6 and a diaphragm. It is divided into the working chamber 7. The second compartment 3 and the third compartment 4 are divided by the diaphragms 10 and 11 into cushion chambers 12 and 13 and air chambers 14 and 15 which are sealed.

The cushion chamber 12 on the side of the second compartment 3 is connected to the pump chamber 6 via a suction valve 17 and serves as a suction side cushion chamber. The cushion chamber 13 on the side of the third ward chamber 4 is connected to the pump chamber 6 via the discharge valve 18 and serves as a discharge side cushion chamber. A suction port 20 is connected to the suction side cushion 12 chamber, and the suction port 20 is connected to a fuel tank (not shown). On the other hand, a discharge port 21 is connected to the discharge side cushion chamber 13, and the discharge port 21 is connected to a fuel inlet of a carburetor (not shown). Further, a rod 23 protruding through the diaphragm working chamber 7 is attached to the pump diaphragm 5, and the rod 23 is advanced and retracted by a cam 25 that cooperates with the engine to vibrate the pump diaphragm 5. Therefore, during operation of the engine, the pump diaphragm 5 is vibrated by the cam 25, and the interaction between the suction valve 17 and the discharge valve 18 sucks the fuel from the fuel tank into the pump chamber 6 and the downstream from the pump chamber 6. It is designed to send fuel to the side vaporizer.

That is, when the pump diaphragm 5 bends in the direction of expanding the volume of the pump chamber 6, the suction valve 17 opens, and the fuel is sucked from the suction port 20 into the pump chamber 6 through the suction side cushion chamber 12. To be done. Further, when the pump diaphragm 5 bends in the direction of contracting the volume of the pump chamber 6, the discharge valve 18 opens, and the fuel is discharged from the pump chamber 6 through the discharge-side cushion chamber 13 and the discharge port 21. .

The above is the structure of a conventional general fuel pump. According to the present invention, the partition wall 27 that separates the air chamber 14 and the air chamber 15 is provided with the port 28 that causes the pressures of the air chambers 14 and 15 to be shifted in phase from each other so that the diaphragms 10 and 11 can be operated. The operation is controlled so as to operate most efficiently with respect to the operation of the pump diaphragm 5, and the fuel discharge amount is increased.

Further, by changing the diameter of the port 28, it is possible to set the peak of the increase in the fuel discharge amount to a predetermined rotation speed, and it is possible to obtain the discharge characteristic that matches the engine characteristic.

In the above embodiment, the diaphragm type pump in which the pump diaphragm is driven by the cam 25 is shown. As shown in FIG. 2, the diaphragm working chamber 7 is formed as a pulse chamber 26. The same effect can be obtained with a diaphragm type pump in which 26 is connected to the pulse generation source of the engine, for example, the crank chamber in a two-cycle engine, and the pump diaphragm 5 is driven by this pulse.

[0014]

[Effect of device]

 As described above in detail, according to the present invention, a port is provided in the partition wall of the air chamber defined at the back of the suction side cushion chamber and the discharge side cushion chamber so that the pressures of the two air chambers act out of phase with each other. Therefore, the operation of each cushion diaphragm can be optimally controlled so that the pump action is performed efficiently in accordance with the operation of the pump diaphragm, and the discharge amount can be increased, thus increasing the size of the fuel pump. The fuel discharge amount can be increased by avoiding the above.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols] 5 pump diaphragm 7 diaphragm working chamber 10 diaphragm (suction side) 11 diaphragm (discharge side) 12 suction side cushion chamber 13 discharge side cushion chamber 14 air chamber (suction side) 15 air chamber (discharge side) 17 suction Valve 18 Discharge valve 27 Partition wall 28 port

Claims (1)

[Scope of utility model registration request] 1. A fuel pump in which a cushion chamber having one wall formed of a diaphragm is provided upstream of the intake valve and downstream of the discharge valve, and a sealed air chamber is provided behind the diaphragm of each cushion chamber. A fuel pump, characterized in that a partition wall is provided with ports for shifting the pressures of the respective air chambers to act on each other.