대표
청구항
▼
1. A fuel pump for pressurizing fuel and pumping the fuel to an accumulation chamber, the fuel pump comprising: a housing having a compression chamber and a first passage, the first passage being configured to communicate the compression chamber with the accumulation chamber;a plunger axially movable in the pump housing for pressurizing fuel in the compression chamber;a discharge valve provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the com...
1. A fuel pump for pressurizing fuel and pumping the fuel to an accumulation chamber, the fuel pump comprising: a housing having a compression chamber and a first passage, the first passage being configured to communicate the compression chamber with the accumulation chamber;a plunger axially movable in the pump housing for pressurizing fuel in the compression chamber;a discharge valve provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the compression chamber;a second passage configured to communicate one passage portion, which is at a side of the accumulation chamber with respect to the discharge valve, with an other passage portion, which is at a side of the compression chamber with respect to the discharge valve, the second passage defining a valve seat midway therethrough;a valve element having a valve element portion configured to be seated on the valve seat and configured to allow fuel flow substantially only from the accumulation chamber to the compression chamber, and a cylindrical portion extending from the valve element portion substantially in an axial direction of the second passage, the cylindrical portion being smaller than the valve element portion in outside diameter, an outer circumferential periphery of the cylindrical portion defining a sliding portion configured to slide along an inner wall of the second passage, to guide lifting and seating of the valve element portion; anda biasing unit for biasing the valve element to seat the valve element on the valve seat,wherein the second passage has a throttle midway therethrough for restricting fuel flow from the accumulation chamber to the compression chamber, andthe throttle is defined between a sidewall of the outer circumferential periphery of the cylindrical portion of the valve element and the inner wall of the second passage. 2. The fuel pump according to claim 1, wherein the cylindrical portion is closer to the accumulation chamber than the valve seat. 3. The fuel pump according to claim 1, wherein the housing has a relief passage,the relief passage has one end, which communicates with one portion of the first passage at a side of the accumulation chamber with respect to the discharge valve, andthe relief passage has an other end, which communicates with an other portion of the first passage at a side of the compression chamber with respect to the discharge valve,the fuel pump further comprising:a relief valve provided in the relief passage,wherein the relief valve is configured to open to release pressure from the accumulation chamber to the compression chamber in response to a condition where the accumulation chamber is at abnormal high-pressure,the relief valve includes the valve element, andthe valve element defines the second passage. 4. The fuel pump according to claim 1, wherein the discharge valve includes the valve element, andthe valve element defines the second passage. 5. The fuel pump according to claim 1, wherein the housing defines the second passage. 6. A fuel pump for pressurizing fuel and pumping the fuel to an accumulation chamber, the fuel pump comprising: a housing having a compression chamber and a first passage, the first passage configured to communicate the compression chamber with the accumulation chamber;a plunger axially movable in the pump housing for pressurizing fuel in the compression chamber;a discharge valve provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the compression chamber;a second passage, which is configured to communicate a passage, which is at a side of the accumulation chamber with respect to the discharge valve, with one of the compression chamber and a low pressure portion, the low pressure portion being located upstream of the compression chamber; anda partition member is located in the second passage for partitioning the second passage into one passage portion at a side of the accumulation chamber and an other passage portion at a side of the compression chamber,wherein the partition member includes a columnar core member and an elastic member,the elastic member is in a cylindrical shape and formed of a material further elastic than the core member,the elastic member surrounds an outer circumferential wall surface of the core member,the elastic member is configured to apply predetermined surface pressure to both a portion between an inner circumferential wall of the elastic member and the outer circumferential wall of the core member and to a portion between an outer circumferential wall of the elastic member and an inner circumferential wall defining the second passage, andthe inner circumferential wall of the elastic member and the outer circumferential wall of the core member define a gap therebetween to allow fuel to pass through the gap from a high-pressure side to a low-pressure side when pressure is applied. 7. The fuel pump according to claim 6, wherein the elastic member includes a cylindrical member and an O-ring,the cylindrical member has an inner circumferential wall being supported by the outer circumferential wall of the core member,the O-ring is made from rubber and provided at a radially outer side of the cylindrical member,the O-ring is in close contact with an outer circumferential wall of the cylindrical member, andthe O-ring is in close contact with the inner circumferential wall defining the second passage. 8. The fuel pump according to claim 7, wherein the partition member has a resistance adjustment portion, andthe resistance adjustment portion is configured to adjust flow resistance of fuel flowing through the gap between the core member and the cylindrical member. 9. The fuel pump according to claim 8, wherein the resistance adjustment portion includes a surface-pressure adjustment portion, which is configured to adjust surface pressure between the core member and the cylindrical member. 10. The fuel pump according to claim 9, wherein the surface-pressure adjustment portion includes a groove formed in at least one of the outer circumferential wall surface of the core member and the inner circumferential wall surface of the cylindrical member. 11. The fuel pump according to claim 9, wherein the core member is configured to be inserted into the inner circumferential wall of the cylindrical member and mounted with the cylindrical member,the inner circumferential wall of the cylindrical member has an inner diameter, which is smaller than an outer diameter of the core member in a condition where the core member is detached from the cylindrical member, andthe surface-pressure adjustment portion is configured by an interference as a difference between the outer diameter of the core member and the inner diameter of the cylindrical member. 12. The fuel pump according to claim 9, wherein the surface-pressure adjustment portion includes the O-ring configured to exert straining force radially inward to fasten the cylindrical member. 13. The fuel pump according to claim 12, wherein the O-ring has an axial length such that the O-ring is restricted axially within both ends of the cylindrical member in an axial direction in a condition where the O-ring is interposed between the cylindrical member and the second passage. 14. The fuel pump according to claim 12, wherein the core member has a stopper portion for restricting both ends of the O-ring in the axial direction from respectively protruding over both ends of the cylindrical member in the axial direction. 15. The fuel pump according to claim 8, wherein the resistance adjustment portion is configured by an axial length of the cylindrical member. 16. The fuel pump according to claim 7, wherein each of the core member and the cylindrical member has a cross section in a radial direction, andthe cross section is substantially in a circular shape. 17. The fuel pump according to claim 6, wherein the elastic member only includes a cylindrical member, andthe cylindrical member has both an the inner circumferential wall, which is supported by the outer circumferential wall of the core member, and an outer circumferential wall, which is supported by the inner circumferential wall defining the second passage. 18. The fuel pump according to claim 17, wherein the partition member has a resistance adjustment portion, andthe resistance adjustment portion is configured to adjust both flow resistance of fuel flowing through a gap between the core member and the cylindrical member and flow resistance of fuel flowing through the gap between the cylindrical member and the second passage. 19. The fuel pump according to claim 18, wherein the resistance adjustment portion includes a surface-pressure adjustment portion, andthe surface-pressure adjustment portion is configured to adjust both surface pressure between the core member and the cylindrical member and surface pressure between the cylindrical member and the inner circumferential wall defining the second passage. 20. The fuel pump according to claim 19, wherein the core member is configured to be inserted into an inner circumferential wall of the cylindrical member and mounted with the cylindrical member,the core member together with the cylindrical member is configured to be inserted into the second passage,in a condition where the core member together with the cylindrical member is detached from the second passage and the core member is detached from the cylindrical member, an inner diameter of the inner circumferential wall of the cylindrical member is smaller than an outer diameter of the core member, and an outer diameter of the outer circumferential wall of the cylindrical member is larger than a passage diameter of the second passage, andthe surface-pressure adjustment portion is configured by an inner interference as a difference between the outer diameter of the core member and the inner diameter of the cylindrical member and an outer interference as a difference between the passage diameter of the second passage and the outer diameter of the cylindrical member. 21. The fuel pump according to claim 18, wherein the resistance adjustment portion is configured by an axial length of the cylindrical member. 22. The fuel pump according to claim 17, wherein each of the core member and the cylindrical member has a cross section in a radial direction, andthe cross section is substantially in a circular shape. 23. The fuel pump according to claim 6, wherein the passage member includes the housing, andthe second passage has one end connected to the compression chamber. 24. The fuel pump according to claim 6, wherein the passage member includes the housing, andthe second passage has one end connected to the low pressure portion. 25. The fuel pump according to claim 6, wherein the passage member includes the discharge valve. 26. The fuel pump according to claim 6, wherein the housing has a relief passage,the relief passage has one end, which is connected to a portion of the first passage at a side of the accumulation chamber with respect to the discharge valve, andthe relief passage has an other end, which is connected to one of the compression chamber and the low pressure portion,the fuel pump further comprising:a relief valve provided in the relief passage and configured to open in response to a condition where the accumulation chamber is at abnormal high-pressure, andthe passage member includes the relief valve. 27. A fuel pump for pressurizing fuel and pumping the fuel to an accumulation chamber, the fuel pump comprising: a housing having a compression chamber and a first passage, the first passage configured to communicate the compression chamber with the accumulation chamber;a plunger axially movable in the pump housing for pressurizing fuel in the compression chamber;a discharge valve provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the compression chamber;a second passage, which is configured to communicate a passage, which is at a side of the accumulation chamber with respect to the discharge valve, with one of the compression chamber and a low pressure portion, the low pressure portion being located upstream of the compression chamber; anda partition member is located in the second passage for partitioning the second passage into one passage portion at a side of the accumulation chamber and an other passage portion at a side of the compression chamber,wherein the partition member includes a columnar core member and an elastic member,the elastic member is in a cylindrical shape and formed of a material further elastic than the core member,the elastic member surrounds an outer circumferential wall surface of the core member,the elastic member is configured to apply predetermined surface pressure to both a portion between an inner circumferential wall of the elastic member and the outer circumferential wall of the core member and to a portion between an outer circumferential wall of the elastic member and an inner circumferential wall defining the second passage,the elastic member includes a cylindrical member and an O-ring,the cylindrical member has an inner circumferential wall being supported by the outer circumferential wall of the core member,the O-ring is made from rubber and provided at a radially outer side of the cylindrical member,the O-ring is in close contact with an outer circumferential wall of the cylindrical member,the O-ring is in close contact with the inner circumferential wall defining the second passage,the partition member has a resistance adjustment portion,the resistance adjustment portion is configured to adjust flow resistance of fuel flowing through a gap between the core member and the cylindrical member,the resistance adjustment portion includes a surface-pressure adjustment portion, which is configured to adjust surface pressure between the core member and the cylindrical member, andthe surface-pressure adjustment portion includes a groove formed in at least one of the outer circumferential wall surface of the core member and the inner circumferential wall surface of the cylindrical member. 28. A fuel pump for pressurizing fuel and pumping the fuel to an accumulation chamber, the fuel pump comprising: a housing having a compression chamber and a first passage, the first passage configured to communicate the compression chamber with the accumulation chamber;a plunger axially movable in the pump housing for pressurizing fuel in the compression chamber;a discharge valve provided in the first passage and configured to open to supply fuel from the compression chamber to the accumulation chamber in response to increase in pressure in the compression chamber;a second passage, which is configured to communicate a passage, which is at a side of the accumulation chamber with respect to the discharge valve, with one of the compression chamber and a low pressure portion, the low pressure portion being located upstream of the compression chamber; anda partition member is located in the second passage for partitioning the second passage into one passage portion at a side of the accumulation chamber and an other passage portion at a side of the compression chamber,wherein the partition member includes a columnar core member and an elastic member,the elastic member is in a cylindrical shape and formed of a material further elastic than the core member,the elastic member surrounds an outer circumferential wall surface of the core member,the elastic member is configured to apply predetermined surface pressure to both a portion between an inner circumferential wall of the elastic member and the outer circumferential wall of the core member and to a portion between an outer circumferential wall of the elastic member and an inner circumferential wall defining the second passage,the elastic member only includes a cylindrical member,the cylindrical member has both an the inner circumferential wall, which is supported by the outer circumferential wall of the core member, and an outer circumferential wall, which is supported by the inner circumferential wall defining the second passage,the partition member has a resistance adjustment portion, and the resistance adjustment portion is configured to adjust both flow resistance of fuel flowing through a gap between the core member and the cylindrical member and flow resistance of fuel flowing through a gap between the cylindrical member and the second passage. 29. The fuel pump according to claim 28, wherein the resistance adjustment portion includes a surface-pressure adjustment portion, andthe surface-pressure adjustment portion is configured to adjust both surface pressure between the core member and the cylindrical member and surface pressure between the cylindrical member and the inner circumferential wall defining the second passage. 30. The fuel pump according to claim 29, wherein the core member is configured to be inserted into an inner circumferential wall of the cylindrical member and mounted with the cylindrical member,the core member together with the cylindrical member is configured to be inserted into the second passage,in a condition where the core member together with the cylindrical member is detached from second passage and the core member is detached from the cylindrical member, an inner diameter of the inner circumferential wall of the cylindrical member is smaller than an outer diameter of the core member, and an outer diameter of the outer circumferential wall of the cylindrical member is larger than a passage diameter of the second passage, andthe surface-pressure adjustment portion is configured by an inner interference as a difference between the outer diameter of the core member and the inner diameter of the cylindrical member and an outer interference as a difference between the passage diameter of the second passage and the outer diameter of the cylindrical member. 31. The fuel pump according to claim 28, wherein the resistance adjustment portion is configured by an axial length of the cylindrical member. 32. The fuel pump according to claim 1, further comprising: a stopper provided at a side opposite to the cylindrical portion of the valve element portion,wherein the cylindrical portion extends into the inner wall of the second passage to define the throttle between the inner wall of the second passage and an outer circumferential of the cylindrical portion when the valve element portion is lifted from the valve seat and is contact with the stopper. 33. The fuel pump according to claim 6, wherein the inner circumferential wall of the elastic member and the outer circumferential wall of the core member define the gap therebetween to allow fuel to pass through the gap from a high-pressure side to a low-pressure side when a differential pressure between the high-pressure side and the low-pressure side through the elastic member is equal to or greater than a predetermined pressure.
