JPH09228923A - Tappet for in-line fuel injection pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tappet for an in-line fuel injection pump of a simple structure, of high tappet rigidity, facilitating manufacture and assembly, having high accuracy and reducing a cost of manufacture. SOLUTION: In a tappet for an in-line fuel injection pump provided with a roller, a semicircular sectional recessed part 21 a storing a roller 24 is formed in a lower surface of a tappet main unit 21, the roller 24 is arranged in the recessed part 21a through a half cut cylindrical bearing metal 23, a metal retainer 25 supporting a width direction end face of the bearing metal 23 is mounted in a lower surface of the tappet main unit 21, the bearing metal 23 is surely supported even without a pawl part and a notch inserting the pawl part, to be effectively brought into press contact with the recessed part, and thereby in the roller 24 held in this metal, a load from a cam 3 is received by the bearing metal 23 over the total length of the roller, and high tappet rigidity is obtained. Force is transmitted to the tappet main unit 21 through the bearing metal 23, so as to reduce an injection pump noise as a whole. Shape of the recessed part 21a of the tappet main unit, bearing metal 23, metal retainer 25, or the like is simplified, high accurate working is facilitated, and a cost of manufacture is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tappet for an in-line fuel injection pump, and more particularly to a roller support structure for a tappet having a roller in contact with a cam at its lower end.

[0002]

2. Description of the Related Art In a row type fuel injection pump 1, as shown in FIG. 4, a spring 4 is attached to a cam 3 of a cam shaft 2 which rotates in an internal combustion engine or the like.
As a result, the tappet 5 is pressed into contact with the tappet 5, and the tappet 5 moves up and down as the camshaft 2 rotates.
Fuel is pressure-fed by a plunger (not shown) which is installed in the pump portion 6 and is connected to the tappet 5, and in the case shown in FIG. 5, a plunger 8 which is connected to the tappet 5 which slides in the pump body 7. . At the lower end of the tappet 5, as shown in FIGS. 5 and 6, a roller 9 that is in contact with the normal cam 3 is supported by a pin 10 on the tappet 5 or the tappet body 5-1 via a bearing metal 11.

By the way, in the supporting structure of the roller 9 shown in FIGS. 5 and 6, a load is vertically applied to the center of the pin 10 supported at both ends of the tappet 5 or the tappet body 5-1 via the roller 9. It will be. According to a study by the inventors, when the ratio of the load and the displacement of the pin 10 with respect to the tappet 5 or the tappet body 5-1 is defined as "tappet rigidity", the tappet rigidity is measured and the cam shown in FIG. Shaft 2, cam 3, spring 4, tappet 5, plunger 8
When the tappet vibration was calculated using a simulation model such as the above, it was found that the tappet vibration changed as shown in FIGS. 8 and 9 depending on the magnitude of the tappet rigidity. That is, when the tappet rigidity is low, the vibration of the tappet becomes large as shown in FIG. 8, which increases the injection pump noise, and when the tappet rigidity is large, the vibration of the tappet becomes small as shown in FIG. The injection pump noise is also reduced. FIG.
The reference numerals in the above indicate the cam shaft 2, the cam 3, the spring 4, the tappet 5, the plunger 8 and the like, and 12 is a governor, 13
Indicates a timer.

Actually, when the tappet 4 having the structure shown in FIG. 6 has the same outer shape by the so-called "shaving", the rigidity of the tappet can be increased. As shown in A of FIG. The injection pump proximity noise when used can be reduced as compared with the injection pump proximity noise (indicated by B in FIG. 10) when the production tappet as shown in FIG. 6 is used. In short, the tappet rigidity has a great influence on the injection pump noise, and therefore it can be said that if the tappet rigidity can be increased, the injection pump noise can be reduced. However, the sharpened tappet is
As a matter of course, since the contact with the cam 3 is a sliding contact, not only is it significantly inferior in wear resistance and heat resistance as compared with a rolling contact such as the tappet shown in FIG. Not at all.

Then, as disclosed in Japanese Utility Model Laid-Open No. 53-45314, as shown in FIGS. 11 and 12, the tappet body 5 is used.
It is conceivable to use a tappet fitted with an intermediate member 14 in which a roller 9 in contact with the cam 3 is rotatably arranged inside the lower end of -1. According to the embodiment of the above publication, FIG.
As shown in FIG. 12, since the roller 9 is held in the recess 14a of the intermediate member 14 for about 3/4 of the entire circumference over the entire length, the load applied to the roller 9 is received by the recess 14a as a whole. Therefore, the displacement of the roller 9 with respect to the tappet body 5-1 is small. Moreover, since the force is transmitted to the tappet body 5-1 via the relatively thick intermediate member 14, it is said that the injection pump noise can also be reduced. Further, the structure described above is advantageous in terms of wear resistance and heat resistance as compared with those shown in FIGS.

[0006]

However, in the tappet shown in FIGS. 11 and 12, it is necessary to hold the roller 9 over the entire length and hold approximately 3/4 of the entire circumference in the recess 14a of the intermediate member 14, In order to effectively reduce the injection pump noise, wear resistance, and heat resistance, in particular, the intermediate member 14 is provided with a concave portion 14a having a long cross section of a semicircle or more and a closed front and rear portion. A material having sufficient hardness as a bearing must be processed with high accuracy, and in view of the manufacturing cost, it is practically impossible to manufacture. The present invention solves the above-mentioned problems in the tappet of the conventional row-type fuel injection pump, has a simple structure, high tappet rigidity, is easy to manufacture and assemble, is highly accurate, and is inexpensive to manufacture. It was devised as a subject of the invention to obtain a tappet.

[0007]

A tappet for a row-type fuel injection pump according to the present invention for solving the above-mentioned problems is a tappet for a row-type fuel injection pump having a roller in contact with a cam at a lower end thereof. Forming a recess having a semicircular cross section for accommodating the roller, arranging the roller in the recess through a semi-cylindrical bearing metal, and suppressing the metal for supporting the widthwise end face of the bearing metal by the tappet. It is attached to the bottom of the main unit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. In FIGS. 1 to 3, 21
Is a tappet body that slides up and down within the range of H in FIG. 1 through the guide 22 in the pump body 7 shown in FIG. 5, for example. On the lower surface side of the tappet body 21, a recess 21a for disposing a bearing metal 23 and a roller 24, which will be described later, having a semicircular shape and slightly longer than the length of the roller 24, and a lower end surface continuous with the periphery of the recess 21a. 21
A stepped recess 21b reaching c is formed. Further, screw holes 21d are formed symmetrically on the extension of the center line in the width direction of the recess 21a. An oil hole 21e reaching the center of the recess 21a is formed on the upper surface side of the tappet body 21. In the case of this example, the reference numeral 23 is a bearing metal having a relatively thick wall and has a semi-cylindrical shape, and is fitted into the recess 21a so as to be in close contact therewith. A roller 24 is in contact with the cam 3 and has a cylindrical shape and is held in the bearing metal 23. Reference numeral 25 denotes a metal retainer, and a symmetrical notch 25a is formed in a circular part so as to fit in the stepped recess 21b, and the roller 24 projects in the central portion with a slight gap around the periphery. Such a square hole 25b is formed, and the square hole 25b
A bolt hole 25c is formed on the extension of the center line in the width direction of b so as to match the screw hole 21d. The bearing metal 23 is supported on both end faces 23a in the width direction,
As shown in FIG. 1, the support is not the entire thickness, but a necessary clearance is provided on the roller 24 side in consideration of the rotation of the roller 24.

When the bearing metal 23, the roller 24 and the metal retainer 25 are assembled to the tappet body 21, the tappet body 21 is turned upside down from that shown in FIGS.
First, the bearing metal 23 is fitted into the recess 21a so as to be in close contact, and then the roller 24 is held by the bearing metal 23. Further, the metal retainer 25 is fitted in the stepped recess 21b by aligning the notch 25a. While being fitted, the roller 24 is projected from the square hole 25b, and the bolt hole 25 is inserted into the screw hole 21d.
After matching c, the bolt 26 may be inserted into the bolt hole 25c, and screwed into the screw hole 21d so as to be tightened. This effectively supports the metal retainer 25, and the bearing metal 24 is pressed against the recess 21a.

In the tappet of the present invention constructed as described above, when it is incorporated in the fuel injection pump, the load from the cam 3 is applied to the bearing metal 2 over the entire length of the roller 24.
Therefore, the displacement of the roller 24 with respect to the tappet body 21 is small, that is, the tappet rigidity is high. Moreover, in this embodiment, the force is transmitted to the tappet body 21 via the relatively thick bearing metal 23, and the noise of the injection pump is further reduced as a whole.

[0011]

According to the tappet of the present invention, a recess having a semicircular cross section for accommodating the roller is formed on the lower surface of the tappet main body, and the roller is disposed in the recess via a half-cut cylindrical bearing metal. Since the bearing metal is supported by the metal retainer, a small bearing can be provided without providing a claw portion on the metal and a notch into which the claw portion is inserted on the inner surface of the semicircular recess like the bearing metal of an engine. The metal is surely supported,
The depressions can be effectively pressed against each other. Further, in the roller held by the bearing metal having such a structure, the load from the cam is received by the bearing metal over the entire length of the roller, so that the displacement of the roller with respect to the tappet body is small, that is, the tappet rigidity is increased. . Moreover, since the force is transmitted to the tappet body via the bearing metal, the sound of the injection pump is reduced as a whole. Further, in the tappet of the present invention, the shape of the recess of the tappet body, the bearing metal, the metal retainer, etc. is simple, and high-precision machining is easy, and the manufacturing cost can be kept low.

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of a tappet of a row-type fuel injection pump of the present invention, which is a view corresponding to an arrow AA in FIG.

FIG. 2 is an enlarged vertical cross-sectional view of a tappet of the row-type fuel injection pump of the present invention, which is a view corresponding to a cross-section taken along the line BB of FIG.

FIG. 3 is an enlarged bottom view of the tappet of the row-type fuel injection pump of the present invention.

FIG. 4 is a perspective view showing a row-type fuel injection pump with a part thereof cut away.

FIG. 5 is a vertical sectional view of a conventional tappet.

FIG. 6 is a vertical cross-sectional view showing a conventional roller support structure for a tappet.

7 is a schematic view showing a simulation model of a cam shaft, a cam, a spring, a tappet, a plunger, etc., FIG. 7a is a front view, and FIG. 7b is a side view.

FIG. 8 is a diagram showing an influence of tappet rigidity on vibration (when tappet rigidity is low).

FIG. 9 is a diagram showing the effect of tappet rigidity on vibration (when tappet rigidity is high).

FIG. 9 is a diagram comparing the effects of high and low tappet rigidity with respect to injection pump noise.

FIG. 11 is a vertical cross-sectional view showing another conventional tappet.

12 is a sectional view taken along the line CC of FIG. 1 row type pump 2 cam shaft 3 cam 4 tappet (conventional) 7 pump body 8 plunger 9 roller (conventional) 10 pin 11 bearing metal (conventional) 12 governor 13 timer 21 tappet body 21a recess 21b stepped recess 23 bearing metal 24 roller 25
Metal suppression.

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[Procedure amendment]

[Submission date] September 9, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of a tappet of a row-type fuel injection pump of the present invention, which is a view corresponding to an arrow AA in FIG.

FIG. 2 is an enlarged vertical cross-sectional view of a tappet of the row-type fuel injection pump of the present invention, which is a view corresponding to a cross-section taken along the line BB of FIG.

FIG. 3 is an enlarged bottom view of the tappet of the row-type fuel injection pump of the present invention.

FIG. 4 is a perspective view showing a row-type fuel injection pump with a part thereof cut away.

FIG. 5 is a vertical sectional view of a conventional tappet.

FIG. 6 is a vertical cross-sectional view showing a conventional roller support structure for a tappet.

7 is a schematic view showing a simulation model of a cam shaft, a cam, a spring, a tappet, a plunger, etc., FIG. 7a is a front view, and FIG. 7b is a side view.

FIG. 8 is a diagram showing an influence of tappet rigidity on vibration (when tappet rigidity is low).

FIG. 9 is a diagram showing the effect of tappet rigidity on vibration (when tappet rigidity is high).

FIG. 10 is a diagram comparing the effects of high and low tappet rigidity with respect to injection pump sound.

FIG. 11 is a vertical cross-sectional view showing another conventional tappet.

12 is a sectional view taken along the line CC of FIG. 1 row type pump 2 cam shaft 3 cam 4 tappet (conventional) 7 pump body 8 plunger 9 roller (conventional) 10 pin 11 bearing metal (conventional) 12 governor 13 timer 21 tappet body 21a recess 21b stepped recess 23 bearing metal 24 roller 25
Metal suppression.

Claims (1)

[Claims] 1. A tappet for a row-type fuel injection pump having a roller in contact with a cam at a lower end, wherein a lower surface of a tappet body is formed with a recess having a semicircular cross section for accommodating the roller.
A row type fuel injection pump characterized in that a roller is arranged in the recess through a half-cylindrical bearing metal, and a metal retainer for supporting a widthwise end face of the bearing metal is attached to the lower surface of the tappet body. Tappet.