Fluid apparatus having pumps and method for controlling the same

Abstract

A fluid apparatus, which is provided for supplying fluid into an internal combustion engine, includes an upstream pump, which is electrically driven, having an outlet port. The fluid apparatus furtehr includes a downstream pump, which is electrically driven, having an inlet port that is connected with the outlet port in series. The fluid apparatus further includes an open-close unit. The open-close unit communicates a fluid passage through which the upstream pump supplies fluid to the internal combustion engine when the downstream pomp stops. The open-close unit blocks the fluid passage when the downstream pomp operates.

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 view showing a fluid apparatus provided to an internal combustion engine, according to a first embodiment;

FIG. 2 is a flowchart showing an operation of a downstream fuel pump of the fluid apparatus in accordance with an operating condition of the engine;

FIG. 3 is a flowchart showing an operation of the downstream fuel pump when the engine is stopped;

FIG. 4 is a schematic view showing a fluid apparatus according to a second embodiment; and

FIG. 5 is a schematic view showing a fluid apparatus according to a third embodiment.

Claims

1. A fluid apparatus for supplying fluid into a fluid-receiving device, the fluid apparatus comprising: an upstream pump, which is electrically driven, having an outlet port;a downstream pump, which is electrically driven, having an inlet port that is connected with the outlet port in series; andan open-close unit,wherein the open-close unit communicates a fluid passage, through which the upstream pump supplies fluid to the fluid-receiving device, when the downstream pomp stops, andthe open-close unit blocks the fluid passage when the downstream pomp operates.

2. The fluid apparatus according to claim 1, wherein the open-close unit is a check valve that blocks the fluid passage by being applied with pressure difference between discharge pressure of the downstream pump and discharge pressure of the upstream pump when the downstream pump operates.

3. The fluid apparatus according to claim 1, further comprising: a pressure control unit for controlling discharge pressure of each of the upstream pump and the downstream pump.

4. The fluid apparatus according to claim 1, wherein the open-close unit communicates the upstream pump with the fluid-receiving device directly through the fluid passage when the downstream pomp stops.

5. A fuel feed appartus for supplying fuel, the fuel feed appartus comprising: the fluid apparatus, according to claim 1, for supplying fuel into the fluid-receiving device,wherein the fluid-receiving device is an internal combustion engine.

6. A method for controlling a fluid apparatus that includes an upstream pump and a downstream pump connected in series for supplying fuel to a fuel rail of an internal combustion engine, the method comprising: starting the upstream pump;starting the downstream pump in accordance with an operating condition of the internal combustion engine so as to increase pressure of fuel in the fuel rail;blocking a fuel passage, via which the upstream pump directly is connected with the fuel rail, when the downstream pump is started;stopping the downstream pump in accordance with the operating condition of the internal combustion engine so as to decrease pressure of fuel in the fuel rail; andcommunicating the fuel passage so as to supply fuel from the upstream pump directly to the fuel rail when the downstream pump is stopped.

7. The method according to claim 6, further comprising: applying pressure difference between discharge pressure of the downstream pump and discharge pressure of the upstream pump to a check valve provided to the fuel passage so as to control communication in the fuel passage.

8. The method according to claim 6, further comprising: stopping the downstream pump when the internal combustion engine is being stopped;communicating the fuel passage when the the downstream pump is stopped; andstopping the upstream pump after elasing a predetermined period from stopping the downstream pump when the internal combustion engine is being stopped.