JPH0658105U - Laura Tappet - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a roller tappet with excellent productivity while surely prohibiting rotational displacement around the axis of the tappet body. [Structure] A tappet body 12 having an axis and slidably inserted in a tappet guide 7, and a tappet body 12 provided on the bottom surface of the tappet body 12 and reciprocating in the axial direction with the rotational movement of a cam 3a. A roller tappet 10 including a roller 14 for allowing the tappet body 12 to be
It has a sliding surface whose distance from the axis changes along the circumferential direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a roller tappet which is provided in a valve operating mechanism of an overhead valve (OHV) type internal combustion engine, a column fuel injection pump for a diesel engine, and the like, and which converts the rotational movement of a cam into a reciprocating movement.

[0002]

[Prior art]

 In the valve train of the OHV type internal combustion engine, the tappet converts the rotational movement of the cam into the reciprocating movement of the push rod to swing the rocker arm. There are two types of tappets, a flat tappet that makes sliding contact with the cam and a roller tappet that makes rolling contact with the cam.

In the flat tappet, the tappet body is formed into a bottomed cylindrical shape, and a portion offset from the center of the bottom surface (cam friction surface) of the tappet body is set as a cam contact position. Therefore, the sliding surface of the tappet body with respect to the tappet guide has a constant distance from the axis along the entire circumference, and the tappet body can be rotated around the axis by utilizing the rotational movement of the cam. As a result, the position of contact with the cam can be constantly changed, and stepped wear of the cam friction surface is prevented.

On the other hand, in order to reduce friction loss between the cam and the tappet and to prevent abrasion of the cam contact portion, in the roller tappet, a roller for cam rolling is attached to the bottom surface of the tappet body having a cylindrical shape with a bottom. ing. Therefore, in this roller tappet, it is necessary to prohibit the rotational displacement of the tapette body in the circumferential direction. In the conventional roller tappet, in order to prevent rotational displacement of the tappet body in the circumferential direction, a guide groove is provided on the sliding surface of the tappet body, and a stopper bolt is inserted into the guide groove from the tapepet guide side of the cylinder block. The tip was protruding. The guide groove extends in the axial direction of the tappet body, that is, in the reciprocating direction.Therefore, the rotation-preventing bolt does not affect the reciprocating motion of the tappet body and the circumferential direction of the tappet body. The rotation displacement of was prohibited.

[0005]

[Problems to be solved by the device]

 However, in the above-described conventional roller tappet, since the tip of the rotation stop bolt slides against the guide groove, the tip of the rotation stop bolt may be worn and broken. There was the problem of rotating in the circumferential direction. Further, when the roller tappet is inserted into the tappet guide during engine production, it is necessary to align the guide groove, which causes a problem of poor productivity.

The present invention has been made to solve the above-mentioned problems, and provides a roller tappet that prohibits the rotational displacement of the tappet body in the circumferential direction without using a special member and that is excellent in productivity. The purpose is to do.

[0007]

[Means for Solving the Problems]

 To achieve the above object, according to the present invention, a tappet body having an axis and slidably inserted in a tappet guide, and a tappet body provided on the bottom surface of the tappet body are provided along with the rotational movement of a cam. In the roller tappet including a roller that reciprocates in the axial direction, the tappet body has a sliding surface that changes a distance from the axial line along the circumferential direction.

[0008]

[Action]

 In order for the tappet body slidably inserted into the tappet guide to be rotatable about its axis, the sliding surface of the tappet body keeps the distance from the axis constant over the entire circumference. It is necessary. In the tappet body of the roller tappet to which the present invention is applied, the sliding surface changes the distance from the axis along the circumferential direction, so that it cannot be rotationally displaced in the circumferential direction.

[0009]

【Example】

 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a roller tappet to which the present invention is applied. This roller tappet is provided in a valve train of an OHV engine, for example. A step portion 1b extending along the longitudinal direction of the cylinder block 1 is provided on a side wall 1a of the cylinder block 1 of the engine, and a cam shaft 3 is arranged at a position below the step portion 1b in the cylinder block 1. ing. Further, a hole-shaped tappet guide 7 is provided at a position corresponding to the cylinder 5 of the step portion 1b. The tappet guide 7 has a substantially elliptical shape that matches the peripheral surface (sliding surface) of the tappet body 12 of the roller tappet 10.

The roller tappet 10 is composed of a tappet body 12 and rollers 14, etc., and the tappet body 12 is slidably inserted into the tappet guide 7. As shown in FIG. 2, the tapette main body 12 has a substantially elliptical shape in the axial direction view shape (plan view shape). Therefore, the sliding surface of the tappet main body 12 with respect to the tappet guide 7 continuously changes the distance from the axis over the entire circumference (L1, L2, L3 ... In FIG. 2). Note that, in FIG. 2, the roller tappet 10 and the like are viewed from the direction of arrow II in FIG.

Further, a hole 12a is formed on the upper surface of the tappet body 12 at the center position thereof, that is, at a position where the axis passes, and the hole 12a extends along the axis and the tappet body 12 It has reached the position near the bottom. A base end of a push rod 16 for rocking a rocker arm (not shown) is inserted into the hole 12a. The roller 14 is attached to the bottom surface of the tappet body 12, and reciprocates the tappet body 12 while rolling with respect to the cam 3a formed on the camshaft 3.

When the engine is started and the cam shaft 3 rotates, the roller tappet 10 converts the rotational movement of the cam 3 a into the reciprocating movement of the push rod 16. In this case, the tappet 10 itself also reciprocates at high speed in the axial direction. However, since the sliding surface of the tappet main body 12 with respect to the tappet guide 7 continuously changes the distance from the axis along the circumferential direction, the tappet main body 12, that is, the tappet 10 rotates in the circumferential direction. Never be ranked.

Further, when the roller tappet 10 is assembled at the time of engine production, the tappet body 12 may be inserted into the tappet guide 7. After inserting the tappet body into the tappet guide like a conventional roller tappet, There is no need to position the tappet body to align the guide groove with the rotation stop bolt. The tappet body of the roller tappet is not limited to the one having the substantially elliptical shape as viewed in the axial direction like the tappet body 12 described above, but the sliding surface with the tappet guide 7 is a distance from the axis line. It suffices if it is changed along the circumferential direction. For example, like the roller tappet 20 shown in FIG. 3, the tappet body 22 may be molded so that its shape in the axial direction is rectangular. Even in this case, the distance from the axis of the sliding surface of the tappet body 22 continuously changes in the circumferential direction (L4, L5, L6 ... In the figure).

Further, like the roller tappet 24 shown in FIGS. 4 and 5, the tappet body 26 may be formed in a bottomed cylindrical shape with a peripheral wall 26a partially cut away. The sliding surface of the tappet body 26 changes the distance from the axis at the portion where the notch 26b is provided. In FIG. 5, the roller tappet 24 and the like are viewed from the direction of arrow V in FIG.

In this case, as a range in which the peripheral wall of the tappet main body is cut out, as shown in FIG. 5, the notch 26b may be provided over substantially half the circumference of the peripheral wall 26a, and the roller tappet 28 shown in FIG. Like the tappet body 29 of FIG. 7, the notch 29b may be provided over about one-third of the entire circumference of the peripheral wall 29a, and further, like the tappet body 31 of the roller tappet 30 shown in FIG. The notches 31b and 31b may be provided at two locations on the peripheral wall 31a.

As shown in FIG. 5, when the notch 26 b is provided in the circumferential wall 26 a of the tappet body 26 approximately half around, the recess 33 is provided in the sliding surface of the tappet guide 7, and the tappet guide 7 It is desirable to avoid interference between the sliding surface and the push rod 16. Further, in the present embodiment, the case where the present invention is applied to the roller tappet of the valve train of the OHV type internal combustion engine has been described, but the applicable roller tappet is not limited to this, and for example, a row fuel injection pump of a diesel engine. Needless to say, the present invention may be applied to a roller tappet or the like which is provided for the above and converts the rotational movement of the cam into the reciprocating movement of the plunger.

[0017]

[Effect of device]

 As described above, since the tappet body of the roller tappet to which the present invention is applied has the sliding surface that changes the distance from the axis along the circumferential direction, the circumferential displacement of the tappet body in the circumferential direction. Can be definitely prohibited. Along with this, since a special member for prohibiting rotational displacement in the circumferential direction can be omitted, positioning and the like at the time of assembly are not required, which is an excellent effect that productivity can be improved. There is.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a roller tappet to which the present invention is applied, as viewed from the outside of a cylinder block.

FIG. 2 is a plan view of the roller tappet of FIG.

3 is a plan view showing a modification of the roller tappet of FIG. 1 and corresponding to FIG.

FIG. 4 is a perspective view showing another embodiment of the roller tappet to which the present invention is applied, as seen from the inside of the cylinder block.

5 is a plan view of the roller tappet of FIG. 4. FIG.

6 is a plan view showing a modified example of the roller tappet of FIG. 4 and corresponding to FIG.

7 is a plan view corresponding to FIG. 5, showing another modification of the roller tappet of FIG.

[Explanation of symbols]

 1 Cylinder Block 1a Side Wall 1b Step 3a Cam 7 Tappet Guide 10, 20, 24, 28, 30 Roller Tappet 12, 22, 26, 29, 31 Tappet Main Body 14 Roller 16 Push Rod 26b, 29b, 31b Notch

Claims (1)

[Scope of utility model registration request] 1. A tappet body which has an axis and is slidably inserted in a tappet guide, and a roller which is provided on the bottom surface of the tappet body and which reciprocates the tappet body in the axial direction in accordance with the rotational movement of a cam. A roller tappet provided with the tappet body, wherein the tappet body has a sliding surface that changes a distance from an axis along a circumferential direction.