Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1997-08-29
1999-03-23
Miller, Carl S.
Internal-combustion engines
Charge forming device
Fuel injection system
123458, 25112907, F02M 3704
Patent
active
058846069
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a system for generating high fuel pressure for a fuel injection system used in internal combustion engines.
One such system is known from European Patent Disclosure EP 0 270 720 A1. There, on the one hand a high-pressure pump downstream of a low-pressure pump is described, and on the other a controller comprising a plurality of hydraulic valves is described. The valves are used to split the volumetric flow furnished by the low-pressure pump into a work flow to be delivered to the high-pressure pump and a residual flow to be relieved into a fuel tank. The valves include at least one pressure limiting valve integrated into a return line and optionally remote-controlled. Also built into the low pressure line alternatively are a throttle valve, a throttle valve adjustable under remote control, a 2/2-way valve and a 3/3-way valve. These last two valves are also remote-controlled.
In the prior art, to control a feed quantity of the low-pressure pump that is virtually dependent on fuel demand, hydraulic component groups are needed that always include a plurality of components.
ADVANTAGES OF THE INVENTION
In the subject of the invention, an electrically controlled flow regulating valve is used in the low pressure line between the low-pressure pump and the high-pressure pump. The valve splits the supplied fuel stream. One part is delivered to the high-pressure pump, and the remainder is relieved into the return loop. The remaining fuel can be used in Diesel engines and others for lubricating the high-pressure pump.
The flow regulating valve, which for instance is an electromagnetically actuated longitudinal slide valve, is incorporated directly into the low pressure line. It requires little space, only two connections that are under fuel pressure, and an electric trigger line. In this way, it is easy to install and to replace.
BRIEF DESCRIPTIONS OF THE DRAWINGS
Further details of the invention will become apparent from the ensuing description of a schematically shown embodiment:
FIG. 1: a hydraulic circuit diagram for a system for generating high fuel pressure with a symbolically shown low-pressure pump and a symbolically shown high-pressure pump, and
FIG. 2: the flow regulating valve in longitudinal section.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
FIG. 1 shows some essential portions of a system for generating high fuel pressure in internal combustion engines. The fuel, which is under high pressure, is delivered to a downstream fuel injection system.
For generating high fuel pressure, the fuel is aspirated from a fuel tank (1) by means of a low-pressure pump (3), which for instance is electrically driven, and is pumped via a flow regulating valve (40) to a high-pressure pump (20) and/or into a return line (13). A filter (2) is built into a suction line (11) disposed between the fuel tank (1) and the low-pressure pump (3). A fine filter (4) is integrated into a low pressure line (12) located between the flow regulating valve (40) and the high-pressure pump (20).
The low pressure line (12) leads to the inlet check valve (31) of the high-pressure pump (20). By way of the previous mentioned valves, which are disposed on or in the high-pressure pump (20), the fuel reaches the cylinder chambers (24). In the three-cylinder high-pressure pump (20) shown, one high-pressure piston (29) moves in each cylinder chamber (24). The piston is guided in a cylinder (23). The high-pressure piston (29) is moved in at least a compression stroke via an eccentric (22) or cam, supported in an eccentric housing (21), with the interposition of an intermediate piston (26). In this process, the intermediate piston (26) pushes the high-pressure piston (29) in front of it. The quantity of fuel present in the cylinder chamber (24) is thus forced into a high pressure line (14) via an outlet check valve (32). Via the high-pressure line (14), the fuel is pumped into a high-pressure fuel reservoir, not shown.
In the intake phase, or as the eccentric stroke is decreasing, the intermediate piston (26) is m
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patent: 5082180 (1992-01-01), Kubo
patent: 5605386 (1997-02-01), Ziegler
patent: 5607137 (1997-03-01), Kanda
Kellner Andreas
Schubert Peter
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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