Field of the invention:
[0001] The invention relates to a roller-tappet in a fuel injection pump.
Background of the invention:
[0002] Fuel injection pump is an essential element for an automobile with diesel engine.
Fuel injection pump is used for pressurizing fuel for injecting pressurized fuel into the fuel
injector. The components of a fuel injection pump include, but are not limited to, a plunger-
barrel assembly, a roller-tappet and a delivery valve assembly. The roller-tappet is used for
transmitting drive force received from the cam actuator to the plunger in the plunger-barrel
assembly. The tappet-body of the roller-tappet rotates due to thrust forces. Hence, a slider is
placed in the fuel injection pump to prevent the tappet-body from rotating. Figure 1A-1B
illustrates a roller-tappet (100) in a fuel injection pump (not shown), in accordance with a prior
art. Figure 1A represents front-view of the roller-tappet (100) and Figure 1B represents
section-view of the roller-tappet (100). The roller-tappet (100) in accordance with the prior art
comprises a roller (102) and tappet-body (104). The roller (102) is a rounded structure in rolling
contact with a cam actuator at one end. The roller (102) is housed in a housing of the fuel
injection pump using a locking pin (106). The other end of the roller (102) is in contact with
the tappet-body (104). The tappet-body (104) is a cylindrical block and is housed in a hollow
bore (not shown) of the housing of the fuel injection pump. The tappet-body (104) is in contact
with a plunger (not shown) of the fuel injection pump through a helical spring (not shown).
[0003] The tappet-body (104) further comprises a slider that includes a shaft (108) and a
head (110). The slider which includes the shaft (108) and the head (110) is machined separately and is press-fitted into the tappet-body (104). The tappet-body (104) along with the slider is arranged in the hollow bore of the housing such that the slider fits in a slot (not shown) of the housing. Fitting the slider inside the slot of the housing prevents the tappet-body (104) from rolling due to side thrust forces exerted on the tappet-body (104) by the roller (102) and a helical spring (not shown).
[0004] However, machining the shaft (108) and head (110) of the slider is tedious since
diameter of the shaft (108) is minute and further the machining of the shaft (108) should be done with accurate precision to attain accurate press-fitting of the shaft (108) into the tappet-body (104). Thus the machining of the shaft (108) is a cumbersome operation.

Brief description of the accompanying drawings:
[0006] Figure 1A-1B illustrates a roller-tappet in a fuel injection pump, in accordance with
a prior art;
[0007] Figure 2A-2B illustrates a roller-tappet in a fuel injection pump, in accordance with
an embodiment of the invention; and
[0008] Figure 3 illustrates a fuel injection pump, in accordance with an embodiment of the
invention.
Detailed description of the embodiments:
[0009] The present disclosure discloses a roller-tappet (200) in a fuel injection pump (300).
The roller-tappet (200) comprising at least a roller (202) arranged in a housing (302) of said fuel injection pump (300) and in rolling contact with a cam actuator (308). The roller-tappet (200) is characterized by a tappet-body (204) for receiving a drive force from the roller (202), the tappet-body (204) comprising an across-flat-section-profile (204a) along a longitudinal axis of said tappet-body (204).
[0010] The present disclosure also discloses a fuel injection pump (300). The fuel injection
pump (300) comprising at least a housing (302), a roller-tappet (200) comprising a roller (202) arranged in the housing (302) and in rolling contact with a cam actuator (308). The fuel injection pump (300) is characterized by a tappet-body (204) for receiving a drive force from the roller (202). The tappet-body (204) comprising an across-flat-section-profile (204a) along a longitudinal axis of the tappet-body (204).
[0011] Figure 2A-2B illustrates a roller-tappet (200) in a fuel injection pump, in accordance
with an embodiment of the invention.
[0012] The below paragraph explains construction of the roller-tappet (200). Figure 2A
represents front-view of the roller-tappet (200) and Figure 2B represents section-view of the roller-tappet (200). The roller-tappet (200) comprises a roller (202) and a tappet-body (204). The roller (202) is arranged in a housing (not shown) of the fuel injection pump (not shown) using a locking pin (206). The housing of the fuel injection pump comprises a circular bore within which the roller (202) is housed. The roller (202) is in rolling contact with a cam actuator. The roller (202) is a circular block used for receiving a drive force from the cam actuator (not shown). The cam actuator includes a cam shaft with a cam lobe. The cam lobe is in rolling contact with the roller (202). Therefore as the cam lobe rotates (drive force) due to the rotation of the cam shaft, the roller (202) also rotates. In addition to the rotation, the roller (202) also

reciprocates between a first position and a second position. Therefore, the drive force from the cam actuator is received by the roller (202).
[0013] The tappet-body (204) is in contact with the roller (202) at one end (204c). The other
end (204d) of the tappet-body (204) is in communication with a plunger of the fuel injection pump through a helical spring (313 in Figure 3). The tappet-body (204) is a cylindrical block and is removably placed in a tappet-bore (not shown) located in the housing of the fuel injection pump. The drive force received by the roller (202) is transmitted to the tappet-body (204). Hence, the tappet-body (204) reciprocates thereby lifting the plunger in the plunger-barrel assembly (not shown) for pressurizing the fuel.
[0014] The tappet-body (204) comprises an across-flat-section-profile (204a) along its
longitudinal axis as shown in the Figure 2. That is, a section cut is made across the longitudinal axis of the tappet-body (204) for obtaining the across-flat-section-profile (204a). Such an across-flat-section-profile (204a) creates a clearance between the tappet-body (204) and the tappet-bore (204b).
[0015] The roller-tappet (200) further comprises a locking rod (310) (shown in Figure 3).
The locking rod (310) is a metallic rod that is receivable by an orifice (shown in Figure 3) in the housing. The locking rod (310) is disposed perpendicular to the longitudinal axis of said tappet-body (204) and along a width of the across-flat-section-profile (204a) of the tappet-body (204). In other words, the locking rod (310) that is receivable by the orifice passes through the clearance created between the tappet-body (204) and the tappet-bore (204b). Thereby preventing the tappet-body (204) from rotating due to side thrust forces exerted on the tappet-body (204) by the roller (202) and the helical spring.
[0016] Therefore, by introducing an across-flat-section-profile (204a) on the tappet-body
(204), the need for a slider is eliminated. The across-flat-section-profile (204a) can be machined easily in contrary to the slider that includes machining of the shaft and the head which is tedious due to minute diameter of the shaft. Hence, machining the across-flat-section-profile (204a) is flexible and safe. Further, by using a locking rod (310) passing along the width of the across-flat-section-profile (204a) of the tappet-body (204), the tappet-body (204) is prevented from rotating due to side thrust forces. It should be noted that the fuel injection pump can include one or more plunger-barrel assemblies. In such cases, each plunger-barrel assembly includes a corresponding roller-tappet (200).
[0017] Figure 3 illustrates a fuel injection pump (300), in accordance with an embodiment
of the invention. The fuel injection pump (300) comprises at least a housing (302), a roller-tappet (200), a plunger-barrel assembly (304) and a helical spring (306). The roller-tappet (200)

comprises a roller (202) and a tappet-body (204). The housing (302) of the fuel injection pump (300) comprises a circular bore (202a) within which the roller (202) is housed. The roller (202) is in rolling contact with a cam actuator (308).
[0018] The roller (202) is a circular block used for receiving a drive force from the cam
actuator (308). The cam actuator (308) includes a cam shaft (not shown) with a cam lobe (308a). Therefore, due to the rotation of the camshaft, the cam lobe (308a) also rotates. As the cam lobe (308a) rotates, the roller (202) is enabled to reciprocate between a first position and a second position. Further, the roller (202) also rotates due to lateral forces exerted on the roller (202) by the cam lobe (308a). Therefore, the drive force from the cam actuator (308) is received by the roller.
[0019] The tappet-body (204) is a cylindrical block and is in contact with the roller (202) at
one end. Another end of the tappet-body (204) is in communication with the plunger of the fuel injection pump (300) through the helical spring (306). The housing (302) of the fuel injection pump (300) comprises a tappet-bore (204b). The tappet-body (204) is removably placed in the tappet-bore (204b). The drive force received by the roller (202) is transmitted to the tappet-body (204). Hence, the tappet-body (204) reciprocates thereby lifting the plunger in the plunger-barrel assembly (304) for pressurizing the fuel.
[0020] The tappet-body (204) comprises an across-flat-section-profile (204a) along its
longitudinal axis. That is, a section cut is made across the longitudinal axis of the tappet-body
(204) for obtaining the across-flat-section-profile (204a). Such an across-flat-section-profile
(204a) creates a clearance between the tappet-body (204) and the tappet-bore (204b).
[0021] The fuel injection pump (300) further comprises a locking rod (310). The housing
(302) of the fuel injection pump (300) comprises an orifice (310a) for receiving the locking rod (310). The locking rod (310) is disposed perpendicular to the longitudinal axis of said tappet-body (204) and along a width of the across-flat-section-profile (204a) of the tappet-body (204). In other words, the locking rod (310) that is receivable by the orifice (310a) passes through the clearance created between the tappet-body (204) and the tappet-bore (204b). Thereby preventing the tappet-body (204) from rotating due to side thrust forces exerted on the tappet-body (204) by the roller (202) and the helical spring (306).
[0022] Therefore, by introducing an across-flat-section-profile (204a) on the tappet-body
(204), the need for a slider in the roller-tappet (200) body for preventing rotation of the tappet-body (204) is eliminated. The across-flat-section-profile (204a) can be machined easily in contrary to the slider that includes machining of the shaft and the head which is tedious due to minute diameter of the shaft. Hence, machining the across-flat-section-profile (204a) is flexible

and safe. Further, by using a locking rod (310) passing along the width of the across-flat-section-profile (204a) of the tappet-body (204), the tappet-body (204) is prevented from rotating due to side thrust forces.
[0023] It should be understood that embodiments explained in the description above are only
illustrative and do not limit the scope of this invention. 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.

CLAIMS
We Claim:
1 A roller-tappet (200) in a fuel injection pump (300), said roller-tappet (200) comprising
at least:
a roller (202) arranged in a housing (302) of said fuel injection pump (300) and in rolling contact with a cam actuator (308); characterized in that
a tappet-body (204) for receiving a drive force from said roller, said tappet-body (204) comprising an across-flat-section-profile (204a) along a longitudinal axis of said tappet-body (204).
2 The roller-tappet (200) as claimed in claim 1, wherein said tappet-body (204) is removably placed in a tappet-bore (204b) defined in said housing (302) of said fuel injection pump (300).
3 The roller-tappet (200) as claimed in claim 1 further comprising:
a locking rod (310) receivable by an orifice in said housing (302), said locking rod (310) disposed perpendicular to said longitudinal axis of said tappet-body (204) and along a width of said across-flat-section-profile (204a) of said tappet-body (204) for preventing rotation of said tappet-body (204).
4 A fuel injection pump (300), said fuel injection pump (300) comprising at least:
a housing (302);
a roller-tappet (200), said roller-tappet (200) comprising a roller (202) arranged in said housing (302) and in rolling contact with a cam actuator (308); characterized in that:
a tappet-body (204), in said roller-tappet (200), for receiving a drive force from said roller, said tappet-body (204) comprising an across-flat-section-profile (204a) along a longitudinal axis of said tappet-body (204).
5 The fuel injection pump (300) as claimed in claim 4, further comprising a tappet-bore
(204b) defined in said housing (302) for receiving said tappet-body (204).

6 The fuel injection pump (300) as claimed in claim 4, further comprising an orifice defined in said housing (302) for receiving a locking rod (310) for preventing rotation of said tappet-body (204).
7 The fuel injection pump (300) as claimed in claim 6, wherein said locking rod (310) receivable by said orifice runs across a tappet-bore (204b) along said across-flat-section-profile (204a) of said tappet-bDisclosed herein is a roller-tappet (200) in a fuel injection pump (300). The roller-tappet comprises at least a roller (202) arranged in a housing (302) of said fuel injection pump (300) and in rolling contact with a cam actuator (308). The roller-tappet (200) is characterized by a tappet-body (204) for receiving a drive force from the roller (202), the tappet-body (204) comprising an across-flat-section-profile (204a) along a longitudinal axis of the tappet-body (204).ody (204).
Dated this 30th day of October, 2017