Description: Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed

Field of the invention
[0001] The present disclosure relates to a solenoid valve that is integrated within a high-pressure fuel pump for an internal combustion engine.

Background of the invention
[0002] The high-pressure fuel pump delivers pressurized fuel that is received from a fuel filter into a common rail under high pressure. For this purpose, the camshaft of the high-pressure fuel pump is driven by the engine and translates the pump pistons to generate the required high pressure. The injection of fuel to the common rail is achieved by the reciprocation of a plunger inside the cylinder of the high-pressure fuel pump. In the current design of the plunger, a stop groove and a helix groove that are defined on the body of the plunger are in flow communication with one another.

[0003] The helix groove allows for the flow of pressurized fuel from the element chamber of the high-pressure fuel pump to a low-pressure fuel gallery via a fuel inlet port at varying stroke lengths of the plunger. Therefore, as the load acting on the high-pressure fuel pump is increased from a low load to a high load, the quantity of pressurized fuel that is delivered from the element chamber of the high-pressure fuel pump to a fuel injector increases in direct proportion to the stroke length of the plunger from the top of the plunger until the helix groove, as the helix groove is rotated by means of a mechanical governor. More specifically, the quantity of pressurized fuel that is delivered from the element chamber of the high-pressure fuel pump to the fuel injector increases in direct proportion to the stroke length of the plunger as the fuel inlet port translates from the top portion of the plunger until the fuel inlet port becomes aligned with the rotating helix groove. Hence, currently the system is purely a mechanical system. Therefore, there exists a need for electronically controlling the fuel delivery for modern-day automobiles.

[0004] US Patent Application US2008025849AA titled “High-pressure fuel pump control apparatus for an internal combustion engine” discloses a control device for a high-pressure fuel pump comprising of: a pressurizing member being reciprocated by rotation of a pump driving cam mounted on the internal combustion engine; a pressurized chamber whose volume is varied by reciprocation of the pressurizing member to perform pump action by repeating a charging stroke and a discharging stroke; and a solenoid valve which is installed as a suction valve in a fuel charging passage to the pressurized chamber such that a pump suction pressure generated in the pressurized chamber in the charging stroke is exerted on the solenoid valve in a valve opening direction, and that is closed at OFF state of an electric driving signal and opened at ON state of the electric driving signal, so that a discharging rate of the high-pressure fuel pump of variable discharge rate type is controlled by an opening and closing control of the solenoid valve. The control apparatus is characterized in that an output as to the ON state of the electric driving signal for the solenoid is set to start on the way of the charging stroke of the high-pressure fuel pump.

Brief description of the accompanying drawings
[0005] An embodiment of the invention is described with reference to the following accompanying drawings:
[0006] Figure 1 depicts a high-pressure fuel pump (100);
[0007] Figure 2 depicts a portion of the high-pressure fuel pump (100).

Detailed description of the preferred embodiment
[0008] Figure 1 depicts a high-pressure fuel pump (100). The high-pressure fuel pump (100) is conventionally part of a fuel injection circuit in an internal combustion engine. The high-pressure fuel pump (100) is stationed downstream from a low-pressure circuit component that includes a fuel filter (not shown) and upstream from a high-pressure component including one of a high-pressure common rail and a fuel injector (not shown). The high-pressure fuel pump (100) comprises a housing (101), a barrel (103), a delivery valve assembly (104), a solenoid valve assembly (106), and at least one plunger (102) that is adapted to reciprocate within an element chamber that is defined within the barrel (103) assembled onto the housing (101) of the high-pressure fuel pump (100). In the exemplary embodiment, a plunger (102) is adapted to reciprocate within the pumping chamber and deliver pressurized fuel to a fuel injector (not shown) that is in flow communication with the high-pressure fuel pump (100).

[0009] The delivery valve assembly (104) is in flow communication with the element chamber and is adapted to control a quantity of pressurized fuel that is delivered from the element chamber to a fuel injector. The most important non-limiting features of the present invention is construction and delivery valve assembly (104), solenoid valve assembly (106) and at least a leak-off groove (108) that is defined in the housing (101) of the fuel pump (100).

[0010] The delivery valve assembly (104) comprises a delivery valve holder (1041) that is in flow communication with the element chamber via a bore (1044) that is defined along the longitudinal axis of the delivery valve holder (1041); a delivery valve pin (1042), the delivery valve pin (1042) in flow communication with the delivery valve holder (1041) via a bore (1043) that is defined on the body of the delivery valve pin (1042) along its longitudinal axis; a unidirectional valve (107) is positioned on the delivery valve pin (1042). The solenoid valve assembly (106) is in electrical and flow communication with the unidirectional valve (107). The leak-off groove (108) is defined on the housing (101) of the fuel pump (100), the leak-off groove (108) adapted to receive fuel from the clearance defined between the delivery valve pin (1042) and the delivery valve holder (1041).

[0011] When fuel in the element chamber attains a pre-defined threshold, pressurized fuel from the element chamber is delivered to a high-pressure circuit via the bore (1043) defined on the delivery valve pin (1042), via the unidirectional valve (107), and via the solenoid valve (106). The translation of the plunger (102) to its top dead center position triggers the solenoid valve to lift the unidirectional valve (107) within a cavity (106) defined in the solenoid valve assembly (106). The leak-off groove (108) receives residual fuel from the element chamber via the clearance, when the action of the solenoid valve lifts the delivery valve pin (1042) to translate away from the bore (1044) defined through the delivery valve holder (1041).

[0012] It should be understood at the outset that, although exemplary embodiments are illustrated in the figures and described below, the present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described below.

[0013] The core of the invention is to deploy a solenoid-based valve and a unidirectional outlet valve (107) for discharging pressurized fuel from the element chamber of the high-pressure fuel pump (100) to a fuel injector. Figure 2 depicts a section of the high-pressure fuel pump (100). As shown in Figure 1, the system consists of the plunger (102) comprising a simple plain plunger (102). The conventional or state of the art stop groove and a helix groove are not defined on the outer periphery of the plunger (102) that normally regulates the quantity of pressurized fuel that is delivered from the element chamber of the high-pressure fuel pump (100) to a high pressure circuit when the plunger (102) translates from its bottom dead center position towards its top dead center position. The presently proposed fuel pump (100) includes an additional circuit for the flow of excess pressurized fuel from the element chamber back to the inlet (105) of the high-pressure fuel pump (100) by means of a leak off groove (108) that will be described in more detail below.

[0014] When the threshold pressure is attained within the element chamber of the high-pressure fuel pump (100) as the plunger (102) translates towards its top dead center position, pressured fuel from the element chamber of the high-pressure fuel pump (100) is delivered to the high-pressure circuit via the bore (1043) that is defined through the delivery valve pin (1042), via the unidirectional valve (107), and via the bore that is defined through the solenoid valve assembly (106). Once the plunger (102) of the high-pressure fuel pump (100) attains the desired effective stroke length, further lift of the plunger (102) to its top dead center position triggers the solenoid valve assembly (106) to actuate the unidirectional valve (107) within a cavity that is defined in the solenoid valve assembly (106) along with the delivery valve pin (1042) that is secured to and in flow communication with the unidirectional valve (107) via an electrical terminal that is controlled by means of the engine control unit (ECU) (not shown).

[0015] When the solenoid valve assembly (106) actuates the unidirectional valve (107) and the delivery valve pin (1042) due to magnetic force that exists between the unidirectional valve (107) and the solenoid valve assembly (106), the delivery valve pin (1042) translates away from the bore (1044) that is defined through the delivery valve holder (1041). The translation of the delivery valve pin (1042) away from the bore (1044) that is defined through the delivery valve holder (1041) in turn opens a fuel passageway in the delivery valve holder (1041) between the element chamber and the leak off port (108) and channels pressurized fuel back to the inlet port (105) of the high-pressure fuel pump (100). Pressurized fuel from the element chamber now flows through an open circuit from the element chamber of the high-pressure fuel pump (100) and into the leak off port via the clearance that is defined between the delivery valve pin (1042) and the delivery valve holder (1041). In varying embodiments, the leak-off port (108) can either be connected to the fuel inlet (105) of the same fuel pump (100) or to a fuel return line leading to a fuel tank.

[0016] Once the excess pressurized fuel is delivered from the element chamber of the high-pressure fuel pump (100) to the leak off port (108), the engine control unit deactivates the solenoid valve. The deactivation of the solenoid valve assembly (106) by the engine control unit causes the delivery valve pin (1042) to be translated towards the bore (1044) that is defined through the delivery valve holder (1041) due to an absence of a magnetic force between the solenoid valve assembly (106) and the delivery valve pin (1042). The translation of the delivery valve pin (1042) towards the bore (1043) that is defined through the delivery valve holder (1041) in turn closes the fuel passageway in the delivery valve holder (1041) between the element chamber of the high-pressure fuel pump (100) and the leak off port (108). Therefore, once the effective stroke length of the plunger (102) has been attained for each element stroke of the plunger (102) of the high-pressure fuel pump (100), no more pressurized fuel from the element chamber of the high-pressure fuel pump (100) is permitted to flow into the high-pressure circuit.

[0017] This idea to develop a high-pressure fuel pump (100) by an elimination of the stop groove and the helix groove defined in the plunger (102) of the high-pressure fuel pump (100) further eliminates the need for a complex governor assembly that normally regulates the quantity of pressurized fuel that is delivered from the high pressure-fuel pump (100). This design dispenses with a need for a rack and pinion gear assembly that is secured between the governor assembly and the sleeve of the plunger (102) of the high-pressure fuel pump (100). Further, in some applications, even the deployment of a high-pressure common rail is not required as the quantity of pressurized fuel that is required to be delivered to the fuel injector is controlled by the solenoid valve assembly (106).

[0018] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification with regard to dimensions of various components are envisaged and form a part of this invention. The scope of this invention is limited only by the scope of the claims.
, Claims: We Claim:
1. A high-pressure fuel pump (100), said high pressure fuel pump (100) comprising: a housing (101), a barrel (103), a plunger (102) adapted to reciprocate within an element chamber defined within the barrel (103) assembled onto the housing (101) of the high-pressure fuel pump (100), a delivery valve assembly (104) in flow communication with the element chamber and adapted to control a quantity of pressurized fuel that is delivered from the element chamber to a high-pressure component:
wherein the delivery valve assembly (104) comprises:
a delivery valve holder (1041) in flow communication with the element chamber via a bore (1043) defined along the longitudinal axis of the delivery valve holder (1041);
a delivery valve pin (1042), the delivery valve pin (1042) in flow communication with the delivery valve holder (1041) via a bore (1043) defined on the body of said delivery valve pin (1042) and extending along its longitudinal axis;
a unidirectional valve (107) positioned on the delivery valve pin (1042);
a solenoid valve assembly (106) in electrical and flow communication with the unidirectional valve (107);
a leak-off port (108) defined on the housing (101) of the fuel pump (100), the leak-off port (108) adapted to receive fuel from the clearance that is defined between the delivery valve pin (1042) and the delivery valve holder (1041).

2. The high-pressure fuel pump (100) as claimed in claim 1, wherein when the fuel in the element chamber attains a pre-defined threshold, pressurized fuel from the element chamber is delivered to a high-pressure circuit via the bore (1043) defined on the delivery valve pin (1042), via the unidirectional valve (107), and via the bore defined in the solenoid valve assembly (106).

3. The high-pressure fuel pump (100) as claimed in claim 1, wherein the translation of the plunger (102) to its top dead center position triggers the solenoid valve assembly (106) to lift the unidirectional valve (107) within a cavity defined in the solenoid valve assembly (106).

4. The high-pressure fuel pump (100) as claimed in claim 1, wherein the leak-off port (108) receives residual fuel from the element chamber via the clearance defined between the delivery valve pin (1042) and the delivery valve holder (1041), when the action of the solenoid valve assembly (106) lifts the delivery valve pin (1042) to translate away from the bore (1043) defined through the delivery valve holder (1041).