CLIAMS:We Claim:
1 A high pressure radial piston pump (100) comprising at least:
a pump housing (105) that defines a pumping chamber (110), an inlet (115) and an outlet (120), wherein said inlet (115) is in fluid communication with an outlet (205) of a fuel metering unit (200) and is used to supply metered quantity of low pressure fuel into said pumping chamber (110), said outlet (120) is in fluid communication with a high pressure rail and is used to supply metered quantity of high pressure fuel into said high pressure rail;
a plunger (125) adapted to perform reciprocal movement within said pumping chamber (110) for pressurizing said low pressure fuel;
a drive chamber (130) comprising a drive shaft (135), said drive shaft (135) is adapted to impart reciprocal movement to said plunger (125);
characterized in that
a lubrication supply line (140) fitted to said pump housing (105), said lubrication supply line (140) in fluid communication with an overflow line (210) of said fuel metering unit 200, wherein said lubrication supply line (140) is used to supply fuel to lubricate said drive chamber (130).

2 A fuel metering unit (200) for supplying lubricant to a high pressure radial piston pump (100) as claimed in claim 1, said fuel metering unit (200) comprising at least:
an outlet (205) in fluid communication with said inlet (115) of said high pressure radial piston pump (100), wherein said outlet (205) is used to supply said regulated quantity of fuel into said pumping chamber (110) through said inlet (115);
characterized in that
an overflow line (210) in fluid communication with said lubrication supply line (140), of said high pressure radial piston pump (100), said overflow line (210) is used to supply fuel to lubricate said drive chamber (130) through said lubrication supply line (140).

3 A fuel supply system (300) comprising:
a high pressure radial piston pump (100) comprising at least a pump housing (105), pumping chamber (110), a drive chamber (130) and a plunger (125);
a fuel metering unit (200) comprising at least an overflow line (210);
characterized in that
a lubrication supply line (140) fitted to said pump housing (105) and in fluid communication with said overflow line (210), wherein fuel from said overflow line (210) is supplied to said drive chamber (130) through said lubrication supply line (140).
,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[001] This invention relates to a high pressure radial piston pump.

Background of the invention
[002] The high pressure radial piston pump comprising at least a pumping chamber, a plunger, a drive chamber and a drive shaft is used for pressurizing fuel. Pressurized fuel is then supplied to a high pressure line. Excess quantity of the pressurized fuel, supplied to the high pressure line, is returned back to the fuel tank using a return valve that is located in the high pressure line. Hence extra quantity of fuel is being pressurized unnecessarily as the excess quantity of the pressurized fuel is returned back to the fuel tank. This decreases efficiency of engine since some amount of energy is utilized for pressurizing the fuel that is returned back to the fuel tank.

[003] As a solution to the above issue, a metering unit is integrated in a housing of the plunger and barrel assembly. The metering unit is used for supplying metered quantity of fuel to the plunger and barrel assembly. Hence, the plunger and barrel assembly pressurizes only the metered quantity of fuel thereby improving the efficiency of the engine. However, in such an assembly, care should be taken that some quantity of fuel is supplied specifically for lubricating the drive chamber. An US publication number US 2006/0201484 shows an arrangement of a lubrication unit in a fuel supply system. Also, since the metering unit is integrated in the housing of the plunger and barrel assembly, the metering unit is required to be made of high quality materials that are expensive. Hence there is still a need for supplying metered quantity of fuel to the high pressure fuel pump in a technique that is inexpensive.

Brief description of the accompanying drawings
[004] Figure 1 illustrates a high pressure radial piston pump in accordance with an embodiment of the present disclosure;

[005] Figure 2 illustrates a fuel metering unit for lubricating a high pressure radial piston pump 100 in accordance with an embodiment of the present disclosure;

[006] Figure 3 illustrates a cross section of the high pressure radial piston pump in accordance with an embodiment of the present disclosure; and

[007] Figure 4 illustrates a fuel supply system in accordance with an embodiment of the present disclosure.

Detailed description
[008] Figure 1 illustrates a high pressure radial piston pump 100 in accordance with an embodiment of the present disclosure.

[009] The high pressure radial piston pump 100 comprises at least a pump housing 105 that defines a pumping chamber 110, an inlet 115 and an outlet 120. The inlet 115 is in fluid communication with the outlet 205 of a fuel metering unit 200, shown in Figure 2, and is used to supply metered quantity of low pressure fuel into the pumping chamber 110. The outlet 120 is in fluid communication with a high pressure rail and is used to supply metered quantity of high pressure fuel into the high pressure rail. The high pressure radial piston pump 100 also comprises a plunger 125, shown in Figure 3, adapted to perform reciprocal movement within the pumping chamber 110 for pressurizing the low pressure fuel and a drive chamber 130, shown in Figure 3, comprising a drive shaft 135. Figure 3 illustrates cut section of the high pressure radial piston pump 100 shown in Figure 1. The drive shaft 135 is adapted to impart reciprocal movement to said plunger 125. The high pressure radial piston pump 100 is also characterized by a lubrication supply line 140 fitted to the pump housing 105. The lubrication supply line 140 is in fluid communication with an overflow line 210 of the fuel metering unit 200 shown in Figure 2. The lubrication supply line 140 is used to supply fuel to lubricate the drive chamber 130.

[0010] The pumping chamber 110 is in fluid communication with the inlet 115. Low pressure fuel, from an outlet 205 of the fuel metering unit 200 shown in Figure 2, is supplied into the pumping chamber 110 through the inlet 115. The inlet 115 is characterized by an inlet valve that includes a spring. The stiffness of the spring is adjusted such that the low pressure fuel flows into the pumping chamber 110 only when the low pressure fuel has a pressure greater than or equal to an opening pressure of the inlet valve. The fuel metering unit 200 supplies metered quantity of fuel to the pumping chamber 110. The low pressure fuel drawn by the pumping chamber 110 is pressurized by the reciprocal movement of the plunger 125, shown in Figure 3, within the pumping chamber 110. The plunger 125 is adapted to reciprocate between a bottom end of the pumping chamber 110 to a top end of the pumping chamber 110. The reciprocal movement of the plunger 125 is obtained using the drive shaft 135, shown in Figure 3, comprised in the drive chamber 130. The pressurized fuel is then delivered to the high pressure line through the outlet 120.

[0011] Once the pressurized fuel is pumped into the high pressure line, the excess fuel from the pumping chamber 110 is discharged into a fuel tank. The excess fuel flows into the fuel tank through a return line 160 of the high pressure radial piston pump 100.

[0012] The high pressure radial piston pump 100 characterized by a lubrication supply line 140 is fitted to said pump housing 105 as shown in Figure 1. The lubrication supply line 140 is in fluid communication with an overflow line 210 of the fuel metering unit 200, shown in Figure 2, and hence fuel from the overflow line 210 flows into the lubrication supply line 140. The fuel flowing through the lubrication supply line 140 is supplied to the drive chamber 130, shown in Figure 3, so that components, for example the drive shaft 135, the plunger 125, polygonal ring, present within the drive chamber 130 may be lubricated.

[0013] The high pressure radial piston pump 100 disclosed in the present disclosure, pressurizes only metered quantity of fuel that is supplied to the pumping chamber 110. Therefore efficiency of the engine is improved. When the engine is being operated at no load condition, the quantity of fuel supplied to the pumping chamber 110 is minimal. Since only minimal quantity of fuel is supplied to the pumping chamber 110, the foot of the plunger is subjected to wear and tear. To overcome this issue, the diameter of the plunger is increased at the foot of the plunger as shown in 150 of Figure 3. The increased diameter at the foot of the plunger enables the plunger to withstand stress since the surface area of the plunger at the foot is increased. Hence wear and tear of the plunger is minimized.

[0014] Also, since only metered quantity of fuel is supplied to the pumping chamber 110 for pressurizing, a separate line called as the lubrication supply line 140 is provided in the high pressure radial piston pump 100 for lubricating the drive chamber 130. The fuel flowing out from the overflow line 210 of the fuel metering unit 200 is supplied to the drive chamber 130 through the lubrication supply line 130 so that the components present in the drive chamber 130 are lubricated.

[0015] Figure 2 illustrates a fuel metering unit 200 for lubricating a high pressure radial piston pump 100 in accordance with an embodiment of the present disclosure. The fuel metering unit 200 comprises at least an outlet 205 in fluid communication with the inlet 115 of the high pressure radial piston pump 100 of Figure 1. The outlet 205 is used to supply the metered quantity of fuel into the pumping chamber 110 through the inlet 115. The fuel metering unit 200 is characterized by an overflow line 210 in fluid communication with the lubrication supply line 140, shown in Figure 1, of the high pressure radial piston pump 100. The overflow line 210 is used to supply fuel, to lubricate the drive chamber 130, through the lubrication supply line 140.

[0016] Inlet 205 of the fuel metering unit 200 is in fluid communication with a fuel tank 250 shown in Figure 4. The fuel stored in the fuel tank enters the fuel metering unit 200 through the inlet 215. The fuel entering through the inlet 215 is regulated by an electronic control valve. In one example, the electronic control valve may be a solenoid valve. Regulation of the fuel is obtained based on engine operating conditions. Further, the metered quantity of fuel passes through the outlet 205 of the fuel metering unit 200.

[0017] The regulated quantity of fuel, from the outlet 205 of the fuel metering unit 200, is supplied to the pumping chamber 110 through the inlet 115 of the high pressure radial piston pump 100 shown in Figure 1. The regulated quantity of fuel is pressurized within the pumping chamber 110 and the pressurized fuel is delivered to the high pressure line through the outlet 120 of the high pressure radial piston pump 100.

[0018] Excess fuel, from the fuel metering unit 200, flows into the overflow line 210 shown in Figure 2. The overflow line 210 is in fluid communication with the lubrication supply line 140, shown in Figure 1, of the high pressure radial piston pump 100. The fuel passing through the lubrication supply line 140 flows into the drive chamber 130 shown in Figure 3. Hence, excess fuel flowing from the overflow line 210 is fed into the drive chamber 130 through the lubrication supply line 140. This fuel fed into the drive chamber 130 is used for lubrication of the components present in the drive chamber 130.

[0019] Hence, by establishing fluid communication between the overflow line 210 of the fuel metering unit 200 and the lubrication supply line 140 of the high pressure radial piston pump 100, the fuel metering unit 200 can be used as a lubricant supply unit for the high pressure radial piston pump 100.

[0020] Figure 4 illustrates a fuel supply system in accordance with an embodiment of the present disclosure.

[0021] The fuel supply system 300 comprises a high pressure radial piston pump 100 comprising at least a pump housing 105, a pumping chamber 110, a drive chamber 130 and a plunger 125 and a fuel metering unit 200 comprising at least an overflow line 210. The fuel supply system 300 is characterized by a lubrication supply line 140 fitted to the pump housing 105 and in fluid communication with the overflow line 210. The fuel from the overflow line 210 is supplied to the drive chamber 130 through the lubrication supply line 140.

[0022] The fuel stored in the fuel tank 250 is supplied to the fuel metering unit 200 through an inlet 215. An electronic control valve, present in the fuel metering unit 200, regulates the fuel supplied. The fuel is metered based on engine operating conditions. Further, metered quantity of fuel flows into the outlet 205 of the fuel metering unit 200. The outlet 205 of the fuel metering unit 200 is in fluid communication with the inlet 115 of the high pressure radial piston pump 100. Hence the fuel from the outlet 205 is supplied into the pumping chamber 110 of the high pressure radial piston pump 100 through the inlet 115. The fuel supplied to the pumping chamber is pressurized due to movement of the piston from a bottom end of the pumping chamber 110 to a top end of the pumping chamber 110. The pressurized fuel is delivered to the high pressure line through the outlet 120.

[0023] Excess fuel from the fuel metering unit 200 flows into the overflow line 210 by the action of an overflow valve. The overflow line 210 is in fluid communication with a lubrication supply line 140 of the high pressure radial piston pump 100 so that the excess fuel from the overflow line 210 flows into the lubrication supply line 140. Fuel passing through the lubrication supply line 140 flows into the drive chamber 130 so that components present in the drive chamber 130 are lubricated. Further, excess quantity of fuel supplied to the drive chamber 130 is returned back to the fuel tank 250 through the return line 160 of the high pressure radial piston pump 100.

[0024] Hence, by using a fuel metering unit 200 in communication with the fuel tank and the high pressure radial piston pump 100, metered quantity of fuel is supplied to the high pressure radial piston pump 100 and hence only the metered quantity of fuel is pressurized thereby avoiding pressurizing excess fuel unnecessarily. Also, by providing a lubrication supply line 140 in fluid communication with the overflow line 210, excess fuel from the fuel metering unit 200 can be used to lubricate the high pressure radial piston pump 100.

[0025] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to type of the high pressure radial piston pump and type of the fuel metering unit are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.