Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
  • F02M59/48—Assembling; Disassembling; Replacing
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/02—Valve drive
  • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
  • F01L1/047—Camshafts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
  • F02M59/10—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by the piston-drive
  • F02M59/102—Mechanical drive, e.g. tappets or cams
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
  • F02M59/445—Selection of particular materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
  • F04B1/0404—Details or component parts
  • F04B1/0413—Cams
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
  • F04B9/02—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical
  • F04B9/04—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members
  • F04B9/02—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical
  • F04B9/04—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms
  • F04B9/042—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics or pin-and-slot mechanisms the means being cams

Definitions

• the present invention relates to a driveshaft assembly, and in particular a driveshaft assembly for transmitting drive in a pump suitable for high pressure fuel supply in a fuel injection system such as a diesel injection system.
• Known driveshaft assemblies for high pressure fuel pumps comprise an elongate shaft element, and an integrally formed cam lobe. To enable the assembly to withstand high cam loads and stresses, it must be formed of a sufficiently hard material, such as a high grade steel, therefore presenting high manufacturing costs.
• Known high pressure fuel pumps may further comprise a thrust washer, to counteract axial loading during use of the pump.
• Thrust washers with free rotating movement are used in the automotive industry for rotary applications in general. Thrust washers free of rotating movement are also known, however in a high pressure fuel pump, such washers could be disadvantageous in terms of noise, cleanliness, and generation of debris which can affect the performance of the pump and or/injector, for example by causing an injector blockage.
• the present invention provides, in a first aspect, a driveshaft assembly according to claim 1.
• the or each cam lobe is an interference fit on the first mid-portion of the shaft and the thrust washer an interference fit on the second mid-portion of the shaft.
• a thrust face of the thrust washer, remote from the or each cam lobe, may be coated.
• the thrust washer and the cam lobe may be bonded to each other.
• the present invention comprises a pump for a high pressure fuel system comprising a driveshaft assembly as described above, the pump comprising a housing and a front plate wherein the driveshaft assembly is rotatable along a longitudinal axis of the driveshaft assembly within a bore provided in the housing and the front plate.
• the present invention comprises a method of assembling a driveshaft assembly comprising steps of assembling the thrust washer onto the second mid-portion of the shaft and assembling the cam lobe onto the first mid-portion of the shaft.
• the thrust washer and the cam lobe may be assembled onto the shaft by at least one of press or force-fitting, laser welding, cold welding and drive dog application.
• the method of assembling a driveshaft assembly may comprise a first set of method steps of:
• the thrust washer allowing the thrust washer to cool whereby the diameter of the bore of the thrust washer reduces during cooling and whereby when cooled to a temperature of the shaft, the thrust washer is an interference fit on the second mid-portion of the shaft;
• the cam lobe allowing the cam lobe to cool to a temperature of the shaft whereby the diameter of bore of the or each cam lobe reduces during cooling and whereby when cooled to a temperature of the shaft, the cam lobe is an interference fit on the first mid-portion of the shaft.
• the second set of method steps described above is undertaken prior to the first set of method steps.
• the method may further comprise a step of coating a thrust surface of the thrust washer.
• the method may further comprise a step of applying an adhesive to a contact surface of the cam lobe which contacts a contact surface of the thrust washer after assembly of the driveshaft assembly, and/or applying an adhesive to the contact surface of the thrust washer.
• Figure 1 is a cross-sectional view of a pump for a high pressure fuel system including the driveshaft assembly according to the present invention.
• FIGS. 2 and 3 are isometric, partially cut out view of a driveshaft assembly in accordance with the present invention.
• Figures 4 and 5 are exploded isometric views of the driveshaft assembly of Figures 1 and 2.
• Figure 1 illustrates a high pressure fuel pump 100 comprising a housing 102 and a front plate 112.
• a driveshaft assembly 2 is arranged for rotation within a bore provided in the housing 102 and front plate 112.
• the driveshaft assembly 2 comprises a shaft 4, a cam lobe 6 and a thrust washer 8.
• the driveshaft assembly 2 is caused, by a driving mechanism (not shown), to rotate relative to the housing 102 and front plate 1 12, around a longitudinal axis A, and in a direction indicated by arrow X in Figure 1.
• Rotation of the driveshaft assembly 2 causes a reciprocating force to be imparted to a plunger 106, via a roller 108, thereby causing fuel within a pumping chamber 110 to become pressurised.
• FIGs 2 to 5 illustrate the driveshaft assembly 2 in isolation.
• the shaft 4 comprises, towards a first end 24, a front journal portion 10, and towards a second end 26, a rear journal portion 12. Between the front journal portion 10 and the rear journal portion 12 is provided a first mid-portion 14, and a second mid- portion 16, which is of a greater cross-sectional diameter than the first mid-portion 14 (the boundaries of the first mid-portion 14 and second mid-portion 16 are indicated by dashed lines on Figure 2).
• the cam lobe 6 is fitted onto the first mid- portion 14 of the shaft 4, and the thrust washer 8 is fitted onto the second mid- portion 16 of the shaft 4, as described in greater detail below.
• the cam lobe 6 is formed of a high grade, relatively hard material, such as a steel, or steel alloy such as M50 (EN ISO 4957 HSP-4-1).
• the shaft 4 and the thrust washer 8 are formed of materials having a relatively reduced hardness, which are of a lower cost than the cam lobe 6.
• An example material for the shaft 4 and thrust washer 8 could be 16MnCrS5 or a mild steel such as EN 10277-3 46S2.
• the thrust washer 8 is provided with a through bore 28 of diameter Dl .
• the cam lobe 6 is provided with a through bore 30 of diameter D2. (Bores 28 and 30, and diameters Dl and D2 are indicated on Figures 4 and 5).
• the thrust washer 8 allows axial loading by the front plate 112, via a thrust surface 20 of the thrust washer 8.
• Axial loading may be due to either internal forces encountered within the high pressure fuel pump 100, or external forces due to the drive mechanism.
• the thrust washer 8 is located in a fixture (not shown) and heated, thereby causing the diameter of the through bore 28 of the thrust washer 8 to be increased to a value greater than Dl .
• the heated thrust washer 8 is then fitted onto the shaft 4, from either the first end 24 or the second end 26 of the shaft 4, to be located over the second mid- portion 16 of the shaft 4. Fitting of the thrust washer 8 onto the second mid-portion 16 of the shaft 4 is enabled by the increased diameter of the through bore 28 of the thrust washer 8 in the heated condition.
• the temperature of the thrust washer 8 is subsequently allowed to decrease, until it equalises with the temperature of the shaft 4. As the temperature of the thrust washer 8 decreases, the diameter of the thrust washer bore 28 decreases, to Dl .
• An external diameter of the second mid-portion 16 of the shaft 4 is selected such that the thrust washer 8, once fitted and cooled to the temperature of the shaft 4, is located by an interference fit on the shaft 4, i.e. an internal surface 36 defining the bore 28 of the thrust washer 8 is an interference fit on an outer surface 42 of the second mid-portion 16 of the shaft 4 (surfaces 36 and 42 are indicated on Figures 4 and 5). Relative movement of the thrust washer 8 on the shaft 4 during use of the pump 100 is thereby prevented by the interference fit between the surfaces 36, 42.
• the cam lobe 6 is heated, thereby causing the diameter of the through bore 30 of the cam lobe 6 to be increased to a value greater than D2.
• the heated cam lobe 6 is then inserted into the shaft via the second end 26 of the shaft 4, over the rear journal portion 12, until it is located over the first mid- portion 16.
• a shoulder 34 formed by the junction of the first mid-portion 14 and the second mid-portion 16 acts as a stop for the cam lobe 6 thereby aiding assembly of the cam lobe 6 onto the shaft 4.
• Fitting of the cam lobe 6 onto the first mid-portion 14 of the shaft 4 is enabled by the increased diameter of the through bore 30 of the cam lobe 6 in the heated condition.
• the cam lobe 6 is subsequently allowed to decrease in temperature, until it equalises with that of the shaft 4.
• the diameter of the through bore 30 decreases, to D2.
• An external diameter of the first mid-portion 14 of the shaft 4 is selected such that the cam lobe 6, once fitted and cooled to the temperature of the shaft 4, is located by an interference fit on the first mid-portion 14 of the shaft 4, i.e.
• an internal surface 38 defining the bore 30 of the cam lobe 6 is an interference fit on an outer surface 40 of the first mid-portion 14 of the shaft 4 (surfaces 38, 40 are indicated on Figures 4 and 5). Relative movement of the cam lobe 6 on the shaft 4 during use of the pump 100 is thereby prevented by the interference fit.
• cam lobe 6 and the thrust washer 8 on the shaft 4 Due to the interference fits between cam lobe 6 and the thrust washer 8 on the shaft 4, the cam lobe 6 and thrust washer 4 also cannot move relative to one another during use of the pump 100.
• a contact face 50 (indicated on Figure 5) of the cam lobe 6 is in contact with a contact portion comprising part of surface 52 (indicated on Figure 4) of the thrust washer 8.
• an adhesive may be applied to the contact face 50 of the cam lobe 6 and/or contact portion of surface 52 of the thrust washer 8, thereby to bond the cam lobe 6 and the thrust washer 8 to one another, thereby further ensuring that the cam lobe 6 and the thrust washer 8 cannot move relative to one another during use of the pump 100.
• the thrust washer 8 and/or the cam lobe 6 may be assembled onto the shaft 4 by press or force-fitting, laser welding, cold welding or "drive dog” application
• drive dog is meant a device used in a lathe (also referred to as a lathe carrier), which clamps the workpiece and allows rotary motion of the spindle of the machine to be transmitted to the workpiece.
• a pin or extrusion could be provided on the thrust washer 8, which fits into a bore provided on the face 50 of the cam lobe 6, or vice versa. Relative movement between the thrust washer 8 and the cam lobe 6 is thereby prevented.
• the thrust washer 8 of the present invention may be coated, for example on the thrust surface 20.
• the cam lobe 6 is heated and assembled onto the shaft 4 before the thrust washer 8 is heated and assembled onto the shaft 4.
• cam lobe 6 Although the embodiment described above includes a single cam lobe 6, in alternative embodiments more than one cam lobe may be provided, each being assembled onto the shaft 4 by the method outlined above.
• the present invention enables a more cost effective driveshaft assembly than prior art embodiments, by allowing a different materials to be used for each of the components.
• the cam lobe 6 can be produced from a high grade material, which has sufficient hardness and strength to be able to withstand high forces and stresses, whilst the shaft 4 and thrust washer 8, which are not subject to forces and stresses of the same magnitude as the cam lobe 6, can be formed of less expensive materials having a relatively lower hardness.
• thrust washer thrust surface 20 shaft first end 24
• cam lobe bore internal surface 36 cam lobe bore internal surface 38 first mid-portion outer surface 40 second mid-portion outer surface 42 cam lobe contact surface 50

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=54347559

Family Applications (1)

Country Status (4)

Families Citing this family (1)

Citations (2)

Family Cites Families (9)

• 2015
  • 2015-10-26 EP EP15784723.7A patent/EP3234342A1/de not_active Withdrawn
  • 2015-10-26 CN CN201580068462.XA patent/CN107110093B/zh active Active
  • 2015-10-26 WO PCT/EP2015/074713 patent/WO2016096206A1/en active Application Filing
  • 2015-10-26 KR KR1020177016336A patent/KR102396682B1/ko active IP Right Grant

Patent Citations (2)

Non-Patent Citations (1)

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