CN110714866A

CN110714866A - Tappet body and fuel injection pump including the same

Info

Publication number: CN110714866A
Application number: CN201810755845.XA
Authority: CN
Inventors: 张伟; 许远
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-07-11
Filing date: 2018-07-11
Publication date: 2020-01-21
Anticipated expiration: 2038-07-11
Also published as: CN110714866B; US20200018296A1

Abstract

The application discloses tappet body and fuel injection pump for fuel injection pump, the tappet body includes: the first concave cavity is arranged at the bottom of the tappet body; a roller rollably and axially movably held in the first cavity by a pin; the second concave cavity is arranged at the top of the tappet body and is provided with an inner end surface vertical to the longitudinal central axis of the tappet body; wherein, the inner end surface is provided with at least one groove which is symmetrical relative to the longitudinal central axis of the tappet body. According to the tappet body of the application, the contact area between the spring seat and the tappet body can be greatly reduced, so that the abrasion caused by friction between the left side end surface and the right side end surface of the roller and the left inner side surface and the right inner side surface of the first cavity of the tappet body is reduced, and the service life of the tappet body and the roller kept on the tappet body is prolonged.

Description

Tappet body and fuel injection pump including the same

Technical Field

The present application relates to a fuel feed system for an internal combustion engine, and more particularly, to a tappet body and a fuel injection pump including the same.

Background

Fuel feed systems for internal combustion engines are well known. A fuel feed system employing a common rail system generally includes a fuel injection pump device, a common rail system, and a plurality of fuel injection valves. Wherein the fuel injection pump device is used for sucking and pressurizing fuel from a fuel tank to a common rail system, the common rail system is used for storing high-pressure fuel from the fuel injection pump device, and each fuel injection valve is arranged in a corresponding cylinder in a plurality of cylinders of an internal combustion engine, so that the high-pressure fuel in the common rail system is fed into each cylinder.

Referring to fig. 1, 2 and 3, a fuel injection pump device 1 of the related art includes a fuel injection pump 9. The conventional fuel injection pump 9 includes: a housing 19 formed with one upright hole 21 or two upright holes 21 arranged side by side and a chamber 28 communicating with the upright hole 21; plunger barrels 13 fitted in the upright holes 21, the plunger barrels 13 having inserted therein plungers 11 capable of reciprocating therein, respectively; a cam shaft 17 rotatably supported, the cam shaft 17 having formed thereon

drive cams

25, 27 corresponding to the plunger 11 and located in a chamber 28. The lower ends of the plungers 11 are seated on the respective tappet bodies 15, a first recess 29 is formed on the side of the tappet bodies 15 facing the

drive cams

25, 27, and a roller 33 is held in the first recess 29 by a pin 31 mounted on the tappet bodies 15 so as to be rollable about the pin 31 and axially movable along the pin 31. A spring 35 and a spring seat 36 are further provided between the plunger sleeve 13 and the tappet body 15. A second cavity 30 is formed in the tappet body 15 on a side remote from the

drive cams

25, 27, and a spring seat 36 is received in the second cavity 30. The spring seat 36 is in contact with the spring 35 on one side and the inner end surface 47 of the tappet body 15 (i.e., the inner end surface of the second cavity 30) on the other side. The spring 35 biases the tappet body 15 toward the camshaft 17 through the spring seat 36, so that the roller 33 always maintains contact with the

respective drive cam

25, 27. Thus, when the camshaft 17 rotates, the plunger 11 reciprocally moves up and down against the outer contour of the

drive cams

25, 27 by the roller 33 held on the tappet body 15 as the contour position of the

drive cams

25, 27 changes.

However, during the up and down movement of the tappet body 15, due to the inherent properties of the coil spring, the repeated compression and extension of the spring 35 causes the spring to twist, generating a torque on the spring seat 36, and further on the tappet body 15 by friction between the spring seat 36 and the inner end surface 47 of the tappet body 15. Since the inner end surface 47 of the tappet body 15 is a ring-shaped plane provided around the central protrusion 16, the contact area between the spring seat 36 and the inner end surface 47 of the tappet body 15 is large, and the friction force therebetween is also large, so that the left and right side end surfaces of the roller 33 of the tappet body 15 are twisted with the spring seat, and contact with the left and right inner side surfaces of the first cavity 29 of the tappet body 15 to generate friction. This friction causes wear on the left and right side end surfaces of the roller 33 and the left and right inner side surfaces of the first recess 29 of the tappet body 15, which shortens the life of the tappet body 15 and the roller 33 held thereon.

Accordingly, there is a need for improvements in the tappet bodies of the prior art.

Disclosure of Invention

It is an object of the present application to overcome the above-mentioned drawbacks of the prior art and to provide a tappet body and a fuel injection pump including the same.

According to one aspect of the present application, there is provided a tappet body for a fuel injection pump, the tappet body including: the first concave cavity is arranged at the bottom of the tappet body; a roller rollably and axially movably held in the first cavity by a pin; the second concave cavity is arranged at the top of the tappet body and is provided with an inner end surface vertical to the longitudinal central axis of the tappet body; wherein, be equipped with in the inner end face for the vertical central axis symmetry's of tappet body at least one recess.

According to an embodiment, the at least one groove is an annular groove and is configured such that at least a part thereof is located at a position of the inner end surface close to an outer periphery of the inner end surface.

According to an embodiment, at least a part of the annular groove is located at a distance from the longitudinal centre axis of the tappet body which is larger than one third of the radius of the inner end surface.

According to an embodiment, the at least one groove is a plurality of radial grooves or a dispersion arrangement of grooves and is configured such that at least a part thereof is located at a position of the inner end surface close to the outer periphery of the inner end surface.

According to an embodiment, at least a part of the plurality of radial grooves or dispersedly arranged grooves is at a distance from the longitudinal centre axis of the tappet body of more than one third of the radius of the inner end surface.

According to an embodiment, the inner end surface is further provided with a central protrusion, and the at least one groove is arranged around the central protrusion.

According to an embodiment, the tappet body is provided with a through hole for communicating the first cavity with the second cavity, and the width of the at least one groove is greater than the diameter of the through hole.

According to another aspect of the present application, there is provided a fuel injection pump including the tappet body described above.

According to an embodiment, the fuel injection pump further comprises:

a jet pump housing formed with at least one upright hole in which the tappet body is disposed and a chamber communicating with the upright hole;

a plunger sleeve fixedly fitted in the upright hole, the plunger sleeve having a plunger inserted therein, the plunger being placed on the tappet body and being capable of reciprocating in the plunger sleeve;

a camshaft rotatably supported by the jet pump housing, the camshaft having a drive cam formed thereon corresponding to the plunger and located in the chamber;

a spring and a spring seat disposed between the plunger sleeve and the tappet body, the spring biasing the roller of the tappet body against the drive cam via the spring seat; and

a fuel inlet and fuel outlet valve assembly provided at an upper end of the plunger barrel, the fuel inlet and fuel outlet valve assembly being configured to allow fuel to be drawn into the fuel injection pump and to cause the fuel drawn into the fuel injection pump to be further pressurized and ejected as the camshaft rotates.

The positive effect of this application lies in: according to the tappet body of the application, the contact area between the spring seat and the tappet body can be greatly reduced, so that the abrasion caused by friction between the left side end surface and the right side end surface of the roller and the left inner side surface and the right inner side surface of the first cavity of the tappet body is greatly reduced, and the service life of the tappet body and the roller kept on the tappet body is prolonged.

Drawings

The foregoing and other aspects of the present application will be more fully understood from the following detailed description, taken together with the following drawings. It is noted that the drawings may not be to scale for clarity of illustration and will not detract from the understanding of the present application. In the drawings:

FIG. 1 illustrates a longitudinal cross-sectional view of a prior art fuel injection pump assembly showing structure within the fuel injection pump body;

FIGS. 2 and 3 show a partially cut-away perspective view and a cross-sectional view, respectively, of a tappet body of the prior art;

FIG. 4 shows a longitudinal cross-sectional view of a fuel injection pump arrangement according to an embodiment of the present application;

fig. 5 and 6 show a partially cut-away perspective view and a cross-sectional view, respectively, of a tappet body according to an embodiment of the present application.

In the various figures of the present application, features that are structurally identical or functionally similar are denoted by the same reference numerals.

Description of reference numerals: the fuel injection pump device 1; a vane pump 3; a fuel metering unit 5; an overflow valve 7; a fuel injection pump 9; a plunger 11; a plunger sleeve 13; a tappet body 15; a central protrusion 16; a camshaft 17; the jet pump housing 19; the jet pump housing parts 19 a; the jet pump housing part 19 b; a vertical hole 21; a bearing 23; the

drive cams

25, 27; a chamber 28; a first cavity 29; a second cavity 30; a pin 31; a roller 33; a spring 35; a spring seat 36; fuel inlet and fuel outlet valve assemblies 37; a recess 38; a plunger chamber 39; the valve holder 41; the fuel injection passage 43; a side end face 45; an inner end surface 47; a through hole 48.

Detailed Description

Preferred embodiments of the present application are described in detail below with reference to examples. It should be understood by those skilled in the art that these exemplary embodiments are not meant to limit the present application in any way.

The structure and operation of the fuel injection pump device of the present application will be generally described below with reference to fig. 4. As shown in fig. 4, a fuel injection pump device 1 according to an embodiment of the present application generally includes a vane pump 3, a fuel metering unit 5, a spill valve 7, and a fuel injection pump 9 assembled together. The vane pump 3 sucks fuel from a fuel tank and delivers the fuel to the fuel metering unit 5, the fuel metering unit 5 can adjust the amount of fuel to be supplied to the fuel injection pump 9, the fuel supplied to the fuel injection pump 9 is pressure-injected to flow to the common rail system, and then the fuel is delivered from the common rail system to the respective fuel injection valves. In the case where the pressure of the fuel supplied to the fuel injection pump 9 exceeds a predetermined pressure, the spill valve 7 may act to discharge a part of the fuel from the fuel injection pump 9. Furthermore, the fuel injection pump arrangement 1 may also comprise a drain valve for returning part of the fuel to the fuel tank.

The fuel injection pump 9 includes two plungers 11, respective plunger bushes 13, respective tappet bodies 15, and a camshaft 17. The camshaft 17 is supported on the injection pump housing 19 with one end of the camshaft 17 projecting through the injection pump housing 19 to receive a driving torque from an engine (not shown) so that the camshaft 17 rotates in synchronization with the engine.

The jet pump housing 19 comprises a jet pump housing part 19a and a jet pump housing part 19 b. The jet pump housing part 19b and the vane pump housing are mounted to the two ends of the jet pump housing part 19a by bolts or the like, and the camshaft 17 is rotatably held on the jet pump housing 19 by bearings 23. Two upstanding holes 21 are formed in the jet pump housing part 19 a.

Drive cams

25 and 27, one for each plunger 11, are formed on the cam shaft 17 and are located in a chamber 28 formed in the jet pump housing part 19a below the upstanding bore 21. It should be noted that only one upright hole 21 may be formed in the jet pump housing part 19 a. Each plunger barrel 13 is fixedly fitted in the corresponding upright hole 21, the plungers 11 are respectively inserted into each plunger barrel 13, and the lower ends of the plungers 11 are seated on the corresponding lifters 15 so as to reciprocate in the plunger barrels 13. The specific structure of the tappet body 15 will be described in detail below with reference to fig. 5 and 6.

As shown in fig. 4, a fuel inlet and fuel outlet valve assembly 37 is provided at the upper end of plunger sleeve 13. A plunger chamber 39 is formed between the fuel inlet and fuel outlet valve assembly 37 and each plunger 11, and a fuel injection passage 43 formed in a valve holder 41 is located above the fuel inlet and fuel outlet valve assembly 37. The specific structure of the fuel inlet and fuel outlet valve assembly 37 is well known in the art, and thus a detailed description thereof will be omitted.

When a plunger moves downward as the lobe position of an actuation cam, such as actuation cam 27 of fig. 4, changes, a negative pressure builds up in the plunger chamber 39 corresponding to the plunger and the fuel inlet and fuel outlet valve assemblies 37 close in a known manner to prevent the back flow of fuel from the common rail system. At the same time as the other plunger moves upwardly as the lobe position of the other drive cam, such as drive cam 25 in fig. 4, changes, a positive pressure is created in the plunger chamber 39 corresponding to that plunger and the fuel inlet and fuel outlet valve assembly 37 is opened in a known manner so that fuel is ejected from the fuel injection passage 43 and delivered to the common rail system. This process is repeated alternately to deliver fuel to the common rail system continuously.

Referring to fig. 5 and 6, a partially cut-away perspective view and a cross-sectional view, respectively, of a tappet body according to an embodiment of the present application, wherein the tappet body is equipped with rollers. The tappet body 15 is substantially cylindrical in shape and has a longitudinal central axis. A first recess 29 is formed in the side of the tappet body 15 facing the drive cams 25 and 27 (i.e., the bottom of the tappet body 15), and a roller 33 is held in the first recess 29 by a pin 31 mounted on the tappet body 15 so as to be rollable about the pin 31 and axially movable along the pin 31. A second cavity 30 is formed in the tappet body 15 on the side opposite to the drive cams 25 and 27 (i.e., the top of the tappet body 15), a central protrusion 16 is provided in the second cavity 30, an inner end surface 47 perpendicular to the longitudinal central axis of the tappet body 15 is formed around the central protrusion 16, and at least one groove 38, for example, an annular groove, is provided in the inner end surface 47 around the central protrusion 16 symmetrically with respect to the longitudinal central axis of the tappet body 15. Of course, the tappet body 15 may also have no central protrusion 16, so that the inner end surface 47 is a generally circular surface.

As shown in fig. 4, a spring 35 and a spring seat 36 are further provided between the plunger sleeve 13 and the tappet body 15. The spring seat 36 is received in the second cavity 30, and one side (i.e., upper side) of the spring seat 36 is in contact with the spring 35 and the other side (i.e., lower side) is in contact with an inner end surface 47 of the tappet 15. The spring 35 biases the tappet body 15 toward the camshaft 17 through the spring seat 36 so that the roller 33 always maintains contact with the

respective drive cams

25 and 27. Thus, when the camshaft 17 rotates, the plunger 11 is reciprocally moved up and down against the outer contours of the

drive cams

25 and 27 by the roller 33 held on the tappet body 15 as the contour positions of the

drive cams

25 and 27 change.

When the camshaft 17 rotates, the driving

cams

25 and 27 move the tappet body 15 up and down, and thus the plunger 11 and the plunger sleeve 13 up and down. Since the spring 35 is located between the spring seat 36 and the plunger sleeve 13, the spring 35 is repeatedly compressed and extended. During the process of compressing and extending the spring 35, due to its inherent properties, the spring 35 generates a torque, which correspondingly drives the spring seat 36 to twist. As described above, the lower side of the spring seat 36 contacts the inner end surface 47 of the tappet body 15, and the torque generated by the spring 35 is transmitted to the tappet body 15 by the friction between the spring seat 36 and the tappet body 15, thereby twisting the tappet body 15. However, since the groove 38 is provided in the inner end surface 47 so that only a part of the lower side of the spring seat 36 is in contact with the inner end surface 47, not the entire lower side of the spring seat 36 is in contact with the inner end surface 47, the contact area between the spring seat 36 and the inner end surface 47 of the tappet 15 is greatly reduced, and thus the frictional force therebetween is reduced, so that the friction between the left and right side end surfaces of the roller 13 of the tappet 15 and the inner side surface of the tappet is reduced.

In the above example, the groove 38 is an annular groove, and is configured such that at least a part of the annular groove is located at a position of the inner end surface 47 near the outer periphery of the inner end surface 47, that is, at least a part of the annular groove is located at a distance greater than one-half of the radius of the inner end surface 47 from the longitudinal center axis of the tappet body 15. This is because, normally, the lower side of the spring seat 36 is in contact with the inner end surface 47 to form an annular contact portion near the outer periphery of the inner end surface 47, and therefore, the groove 38 is provided in the portion of the inner end surface 47 in contact with the spring seat 36 to reduce the contact area of the spring seat with the tappet. In addition, the provision of the groove 38 at a position of the inner end surface 47 near the outer periphery thereof more reduces the torque transmitted to the tappet body in consideration of the moment of friction. Preferably, at least a portion of the annular groove is located at a distance greater than one third of the radius of the inner end surface 47 from the longitudinal center axis of the tappet body 15.

In another example, the groove 38 may be a plurality of radial grooves or discretely arranged grooves, and is configured such that at least a portion of the plurality of radial grooves or discretely arranged grooves are located at a position of the inner end surface 47 near the outer periphery of the inner end surface 47, i.e., at least a portion of the plurality of radial grooves or discretely arranged grooves are located at a distance greater than one-half of the radius of the inner end surface 47 from the longitudinal center axis of the tappet 15. Preferably, the distance is larger than one third of the radius of the inner end surface 47.

Further, it should be noted that the present application contemplates that the position of the groove may be adjusted accordingly, depending on the position of contact of the spring seat with the inner end surface of the tappet body.

As shown in fig. 5 and 6, the tappet body 15 may also be provided with at least two through holes 48 for communication between the first cavity 29 and the second cavity 30, so as to maintain pressure equilibrium between the two cavities. In this example, the width of the groove 38 may be greater than the diameter of the through-hole 48 to reduce the contact area between the spring seat and the tappet body and facilitate machining. The present application also contemplates that the width and depth of the groove 38 may be further adjusted depending on the size of the tappet body and the spring seat and will not be described further herein.

Therefore, by providing the groove 38 in the inner end surface 47 of the tappet body 15, the contact area between the spring seat and the tappet body can be greatly reduced, so that the wear caused by friction between the left and right side end surfaces of the roller and the left and right inner side surfaces of the first cavity of the tappet body is greatly reduced, and the service life of the tappet body and the roller held thereon is prolonged.

While specific embodiments of the present application have been described above, it will be understood by those skilled in the art that this is by way of illustration only, and that the scope of the present application is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and principles of this application, and these changes and modifications are intended to be included within the scope of this application.

Claims

1. A tappet for a fuel injection pump, the tappet (15) comprising:

a first cavity (29) arranged at the bottom of the tappet body (15);

a roller (33) held in the first cavity (29) so as to be rollable and axially movable by means of a pin (31);

a second cavity (30) disposed at a top of the tappet body (15), the second cavity (30) having an inner end surface (47) perpendicular to a longitudinal center axis of the tappet body (15);

characterized in that at least one groove (38) is provided in the inner end surface (47) symmetrically with respect to the longitudinal center axis of the tappet body (15).

2. The tappet according to claim 1, wherein the at least one groove (38) is an annular groove and is configured such that at least a portion thereof is located at a position of the inner end surface (47) near an outer periphery of the inner end surface (47).

3. The tappet according to claim 2, wherein at least a portion of the annular groove is located at a distance from a longitudinal center axis of the tappet that is greater than one third of a radius of the inner end surface (47).

4. The tappet according to claim 1, wherein the at least one groove (38) is a plurality of radial grooves or discretely arranged grooves and is configured such that at least a portion thereof is located at a position of the inner end surface (47) near an outer periphery of the inner end surface (47).

5. Tappet according to claim 4, wherein at least a part of the plurality of radial grooves or dispersedly arranged grooves is at a distance from the longitudinal centre axis of the tappet which is greater than one third of the radius of the inner end surface (47).

6. Tappet according to claim 1, wherein the inner end surface (47) is further provided with a central protrusion (16) and the at least one groove (38) is arranged around the central protrusion (16).

7. Tappet body according to any one of claims 1-6, characterized in that the tappet body (15) is provided with a through hole (48) for communication of the first recess (29) and the second recess (30), and that the width of the at least one groove (38) is larger than the diameter of the through hole (48).

8. A fuel injection pump, characterized by comprising a tappet body (15) according to any one of claims 1-7.

9. The fuel injection pump of claim 8, further comprising:

a jet pump housing (19) formed with at least one upright hole (21) and a chamber (28) communicating with the upright hole (21), wherein the tappet body (15) is provided in the upright hole (21);

a plunger sleeve (13) fixedly fitted in the upright hole (21), a plunger (11) being inserted in the plunger sleeve (13), the plunger (11) being placed on the tappet body (15) and being capable of reciprocating in the plunger sleeve (13);

a camshaft (17) rotatably supported by the jet pump housing (19), the camshaft (17) having formed thereon drive cams (25, 27) corresponding to the plunger (11) and located in the chamber (28);

a spring (35) and a spring seat (36) provided between the plunger sleeve (13) and the tappet body (15), the spring (35) biasing a roller (33) of the tappet body (15) against the drive cam (25, 27) through the spring seat (36); and

a fuel inlet and fuel outlet valve assembly (37) disposed at an upper end of the plunger barrel (13), the fuel inlet and fuel outlet valve assembly (37) being configured to allow fuel to be drawn into the fuel injection pump and to cause the fuel drawn into the fuel injection pump to be further pressurized and ejected as the camshaft (17) rotates.