CLIAMS:We Claim:
1. A delivery valve holder (100) for a fuel injection pump,
said delivery valve holder (100), having a flow passage (103),
said flow passage (103) accommodating at least
a delivery valve body (102);
a delivery valve pin (104); and
a first spring (106) abutting said delivery valve pin 104, characterized in that
a flow control member (108) abutting said spring (106);
a valve plate (110) abutting said flow control member (108); and
a second spring (115) abutting said valve plate 110.
said flow control member (108) having a central hole (112), and at least one radial hole (114), said high pressure fuel adapted to flow through said central hole through compression of said first spring 106 by said delivery valve pin 104 and said high pressure fuel adapted to flow through said at least one radial hole through compression of said second spring 115 by said valve plate (110).

2. The fuel injection pump (100) of claim 1, wherein the diameter of said central hole (112) is less than the diameter of said at least one radial hole (114).

3. The fuel injection pump of claim 1, wherein the diameter of said central hole (112) is greater than the diameter of said at least one radial hole (114).

4. The fuel injection pump of claim 1, wherein said second spring (115) creates a gap between said valve plate (110) and flow control member (108). ,TagSPECI:Complete specification: The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[0001] This invention relates to the field of a delivery valve holder for a fuel injection pump.
Background of the invention
[0002] In a fuel injection pump, fuel from the pressurizing chamber is sent to the injector via a delivery valve holder. The delivery valve holder that is currently in use has a filler piece, a support plate a valve guide, valve plate and a pair of compression springs. The pressurized fuel has to pass through the above mentioned components in order to reach the high pressure pipe and the injector. Since the above mentioned components are housed within the constrained space of the delivery valve holder, the dead volume in the delivery valve holder, which is the amount of fuel that is remaining in the delivery valve holder, after the fuel discharge has been completed, is high. Higher dead volume causes a reduction in quantum of fuel reaching the injector and reduction in injection pressure. Hence there is a need to reduce the dead volume in the delivery valve holder, by reducing the number of components through which the fuel passes. Also, since the current delivery valve holder, as mentioned above, has number of components that needs to be assembled, there is also a need to simplify the assembly process. While the present assembly process of the components of the delivery valve holder involves peel riveting of valve body to the delivery valve holder. The rivet includes rejections include folding, crack, ruptures or defective spot (hollow spaces between riveting interfaces). Lower peel riveting force involves loose fitting of inner components as precise lift length has to be set while higher force involves rising of burrs or undesired flow of material. The riveting process must be optimized with peel riveting force. Other issues involving rusting of rivet surface, widening of hexagon cross flat length and material inclusions like chip and dirt.
[0003] Prior art patent application US6131607 discloses a delivery valve that includes a body defining a chamber into which from one end thereof extends a tubular support member. The interior of the member is connected to the outlet of a fuel pump and an outlet extends from the chamber to a fuel nozzle. Slidable about the support member is a first valve element which defines a seating in its end presented to the other end of the chamber. A second valve element is provided for engagement with the seating and a spring urges the first valve element into engagement with the second valve element. The first valve element also defines a surface against which the fuel pressure in the interior of the tubular member can act to lift the first valve element away from the second valve element to allow fuel flow from the outlet.
Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a delivery valve holder for a fuel injection pump;
[0006] FIG. 2 illustrates a delivery valve holder of the fuel injection pump during the delivery of high pressure fuel to the injector; and
[0007] FIG. 3 illustrates a delivery valve holder of the fuel injection pump during throttling of return high pressure fuel.
Detailed description of the embodiments
[0008] FIG. 1 illustrates a delivery valve holder 100 for a fuel injection pump. A delivery valve holder assembly 100 in a fuel injection pump is used to deliver pressurized fuel received due to reciprocating motion of a plunger inside a pressurizing chamber (Not shown). The delivery valve holder 100 is in flow communication with a high pressure pipe that opens into an injector (Not shown). The fuel pumped into the high pressure pipe is delivered to the engine cylinder via the injector. The delivery valve holder 100 also receives the return flow of the high pressure fuel, when the injector is closed through the high pressure pipe. The fuel that is returning from the injector must be throttled in order to reduce the back pressure of the fuel and prevent damage to the components of the delivery valve holder 100 and high pressure pipe. The subject of interest here is about directing pressurized fuel from the pressurizing chamber to the injector via the delivery valve holder 100 and throttling of return flow of fuel from the injector (when the injector is closed) back to the delivery valve holder 100. The same will be described in further detail.
[0009] The proposed delivery holder 100 has a flow passage 103 accommodating at least a delivery valve body 102, a delivery valve pin 104, and a first spring 106 abutting the delivery valve pin 104. The delivery valve holder 100 is characterized in having a flow control member 108 abutting the spring 106, a valve plate 110 abutting the flow control member 108, and a second spring 115 abutting the valve plate 110. The flow control member 108 has a central hole 112, and at least one radial hole 114, the high pressure fuel is adapted to flow through the central hole through compression of the first spring 106 by the delivery valve pin 104, and the high pressure fuel is adapted to flow through at least one radial hole through compression of the second spring 115 by the valve plate 110. The diameter of the central hole 112 is less than the diameter of at least one radial hole 114. The diameter of the central hole 112 may be greater than the diameter of the radial hole 114.
[00010] FIG. 2 illustrates a delivery valve holder 100 of the fuel injection pump during the delivery of high pressure fuel to the injector. To begin with, fuel that is received from the tank is pressurized in the pressurizing chamber, the pressurized fuel reaches the delivery valve holder 100, due to reciprocating action of the plunger that is present in the pressurizing chamber. The pressurized fuel lifts the delivery valve pin 104 accompanied by compression of the first spring 106. The delivery valve pin 104 abuts the flow control member 108. Now, the fuel has a path through which it can flow through the flow control member 108, the path being the central hole 112 and at least one radial hole 114. The pressure of the fuel causes the valve plate 110 that is abutting the flow control member 108 to lift and compress the second spring 115. The compression of the second spring 115 creates a gap between the valve plate 110 and the flow control member 108. The valve plate 110 has an opening that is co-axial to the central hole 112 of the flow control member 108. The pressurized fuel flows through this opening and reaches the high pressure pipe that is in flow communication with the injector. In this way, the fuel reaches the injector for injection into the engine cylinder.
[00011] FIG. 3 illustrates a delivery valve holder 100 of the fuel injection pump during throttling of return high pressure fuel. As discussed in the detailed description of FIG.2, the pressurized fuel reaches the injector for injection into the engine cylinder. When the injector closes, there is always some amount of residual fuel that is remaining in the high pressure pipe leading to the injector. The only path that is available for the high pressure fuel is to return to the delivery valve holder 100. In case the high pressure fuel returns by maintaining the same pressure that is available at the injector, then there is a possibility of the high pressure fuel causing damage to the components of the injector and the delivery valve holder 100. Excessive pressure of the fuel can even cause the high pressure pipe to explode or rupture. In order to avoid the above mentioned scenario, the high pressure fuel needs to be throttled. As seen from the FIG. 3, the high pressure fuel that is returning towards the delivery valve holder 100, first compresses the second spring 115. The compression of the second spring 115 causes the valve plate 110 to close the gap that was created between the valve plate 110 and the flow control device during the delivery of fuel to the injector. The valve plate 110 abuts the flow control device and closes the radial hole 114 and/ or multiple radial holes. The only available path for the fuel to flow is the central hole 112. Since the central hole 112 has a smaller diameter (approximately 0.5 times the diameter of the radial hole 114), the fuel flows through the restricted space, leading to a drop in pressure of the return high pressure fuel by throttling effect. The residual fuel generally remains in the dead volume present on the delivery valve holder 100. The dead volume mentioned here, is generally, the space that is available in-between the components of the delivery valve holder 100. Since the number of components through which the fuel passes during the return stroke, is less, as compared to the existing fuel injection pump, a reduction in reduction in dead volume is available with the proposed delivery valve holder. The residual fuel in the dead volume moves along into the injector during the next delivery stroke or mixes with it.
[00012] With the use of the above mentioned flow control member 108 in conjunction with valve plate 110 and the first spring 106 and second spring 115, it is possible to bring about a reduction in the total number of components through which the fuel passes within the delivery valve holder 100. By, reducing the dead volume in the delivery valve holder 100, for every stroke of the plunger, the quantum of fuel reaching the high pressure pipe increases. Due to reduced number of components in delivery valve holder 100, the overall weight of the fuel injection pump is also reduced. Also, the components i.e. the flow control member 108, valve plate 110, the first spring 106 and the second spring 115 can be easily assembled, thereby eliminating complex assembly process like peel riveting and improving interchange ability of the components.
[00013] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of profile of the flow control member and the arrangement of holes in the flow control member , and the type of fuel injection pump used and the configuration of the injector. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.