Fuel feed apparatus

Abstract

A fuel feed apparatus connects with an injector and a reservoir tank. The reservoir tank is in upstream of the injector for accumulating fuel for the injector. A fuel pump press-feeds fuel in a fuel tank toward the reservoir tank in accordance with pressure in the reservoir tank. A press-feed pipe defines a fuel passage from the fuel pump to the reservoir tank. A branch pipe is provided to the press-feed pipe. The branch pipe defines a return passage that branches from the fuel passage. Fuel discharged from the fuel pump returns into the fuel tank through the return passage. A throttle unit is provided to the branch pipe for reducing a sectional area of the return passage. A relief valve is provided to the branch pipe for communicating the return passage when pressure in the return passage becomes equal to or greater than relief pressure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic diagram showing a fuel feed system including a fuel feed apparatus according to a first embodiment;

FIG. 2 is a schematic diagram showing a fuel pump of the fuel feed system;

FIG. 3 is a sectional view showing the fuel pump in a fuel tank; and

FIG. 4 is a sectional view showing a fuel pump according to a second embodiment.

Claims

1. A fuel feed apparatus connecting with a fuel tank, an injector, and a reservoir tank, the injector being adapted to injecting fuel, the reservoir tank being arranged in upstream of the injector with respect to fuel flow for accumulating fuel for the injector, the fuel feed apparatus comprising: a fuel pump that press-feeds fuel from the fuel tank toward the reservoir tank in accordance with pressure in the reservoir tank;a press-feed pipe that defines a fuel passage from the fuel pump to the reservoir tank;a branch pipe that is provided to the press-feed pipe, the branch pipe defining a return passage that branches from the fuel passage, fuel discharged from the fuel pump returns into the fuel tank through the return passage;a throttle unit that is provided to the branch pipe for reducing a sectional area of the return passage; anda relief valve that is provided to the branch pipe,wherein the relief valve communicates the return passage when pressure of fuel in the return passage becomes equal to or greater than relief pressure.

2. The fuel feed apparatus according to claim 1, wherein the relief valve is a diaphragm type valve.

3. The fuel feed apparatus according to claim 1, wherein the throttle unit is provided to upstream of the relief valve in the return passage.

4. The fuel feed apparatus according to claim 1, further comprising: a jet pump that includes a jet nozzle communicating with a downstream end of the branch pipe, the jet nozzle being adapted to jetting fuel by pressure caused by fuel discharged through the branch pipe,wherein the jet pump further includes a casing that accommodates the jet nozzle, the casing defining a chamber therein, the chamber generating suction pressure by jetting fuel through the jet nozzle, andthe jet pump further includes an inlet pipe that communicates with the chamber for introducing fuel toward the chamber by the suction pressure.

5. The fuel feed apparatus according to claim 1, wherein the sectional area of the return passage defined in the throttle unit is equal to or less than 0.8 mm2.

6. The fuel feed apparatus according to claim 1, further comprising: a filter that is provided to upstream of the throttle unit in the return passage for removing foreign matters contained in fuel.

7. The fuel feed apparatus according to claim 1, further comprising: a housing that accommodates the fuel pump therein,wherein the throttle unit and the relief valve are accommodated in the housing.

8. The fuel feed apparatus according to claim 1, wherein the relief valve includes a diaphragm that partitions an interior of the relief valve, andthe relief valve further includes a valve member that communicates and blocks the return passage in conjunction with pressure applied to the diaphragm.

9. A fuel feed apparatus connecting with a fuel tank, an injector, and a reservoir tank, the injector being adapted to injecting fuel, the reservoir tank being arranged in upstream of the injector with respect to fuel flow for accumulating fuel for the injector, the fuel feed apparatus comprising: a fuel pump that press-feeds fuel from the fuel tank toward the reservoir tank in accordance with pressure in the reservoir tank;a press-feed pipe that defines a fuel passage from the fuel pump to the reservoir tank;a branch pipe that is provided to the press-feed pipe, the branch pipe defining a return passage that branches from the fuel passage, fuel discharged from the fuel pump returns into the fuel tank through the return passage; anda relief valve that is provided to the branch pipe,wherein the relief valve communicates the return passage when pressure of fuel in the return passage becomes equal to or greater than relief pressure.