JPH1061415A - Valve gear of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the height in the axial direction of a valve body to small dimension so as to make an engine compact and reduce its weight. SOLUTION: A pair of rollers 14, 14 are pressed by a cam 21, and a valve body 3 is pressed through a shaft 13 which supports these rollers 14, 14. An end part of a valve stem 4 and a part of the rollers 14, 14 are superimposed in the axial direction of the shaft 13. Consequently, it is possible to reduce distance between an upper end face of the valve stem 4 and an outer peripheral face of the cam 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A valve train for an engine according to the present invention is provided with a valve for opening and closing an intake port or an exhaust port of an engine used for running an automobile, etc., in synchronization with rotation of a crankshaft. Move back and forth.

[0002]

2. Description of the Related Art An intake valve and an exhaust valve of an engine reciprocate in synchronization with the rotation of a crankshaft and must open and close an intake port or an exhaust port. Such a valve operating device for reciprocating the intake valve and the exhaust valve includes a camshaft that rotates in synchronization with the rotation of the crankshaft, and a camshaft that is supported by an intermediate portion of the camshaft and rotates together with the camshaft. And a valve lifter that reciprocates the intake valve or the exhaust valve based on the displacement of the outer peripheral surface of the cam. The intake valve and the exhaust valve are urged in a direction to close the intake port or the exhaust port by a valve spring provided between the intake valve and the exhaust valve. The valve lifter displaces the intake valve and the exhaust valve against the elasticity of the valve spring as the camshaft rotates.

In recent engines, a pivot is supported by the valve lifter, a roller is rotatably supported around the pivot, and an engaging portion between the valve lifter and the cam is brought into rolling contact. I have. Thus, by bringing the valve lifter and the engaging portion of the cam into rolling contact with each other, the frictional force acting on this engaging portion can be reduced, and the fuel consumption rate can be improved. The basic structure of a valve gear incorporating such a roller is described in Japanese Utility Model Laid-Open No. 62-1.
As described in JP-A-52002, JP-A-63-22306, JP-A-4-44405, etc., it has been widely known.

In each of the structures described in the above publications, a valve lifter that reciprocates in synchronization with a valve element that opens and closes a port that opens to a combustion chamber of an engine, and a camshaft that rotates in synchronization with a crankshaft of the engine And a valve spring for rotating the valve body together with the camshaft, and applying a resilient force to the valve body in a direction to close a port communicating with the combustion chamber. Further, among the structures described in the above publications, Japanese Utility Model Laid-Open No. 152002/1987 and 63
In the valve operating apparatus for an engine described in Japanese Patent No. -22306, a roller is rotatably supported around a pivot supported by the valve lifter, and an outer peripheral surface of the cam is brought into contact with an outer peripheral surface of the roller. As a result, the valve body is reciprocally movable in synchronization with the rotation of the crankshaft. During operation of the engine, the rollers transmit the movement of the cam to the valve body while rotating. The state of contact between the outer peripheral surface of these rollers and the outer peripheral surface of the cam is almost complete rolling contact.

On the other hand, in the valve operating device for an engine described in Japanese Utility Model Application Laid-Open No. 4-44405, a thrust rolling bearing is provided on the top surface of the valve lifter (the surface opposite to the valve body at one axial end surface). The outer peripheral surface of the cam is brought into contact with a position off the center of the thrust rolling bearing. During operation of the engine, the thrust rolling bearing transmits the movement of the cam to the valve body while rotating in the direction around the central axis of the valve body. The contact state between the surface of the thrust rolling bearing and the outer peripheral surface of the cam is a state in which rolling contact and sliding contact are mixed.

[0006]

Problems to be Solved by the Invention
In the case of the valve operating devices for engines described in JP-A Nos. 02 and 63-22306, the cam, the roller, and the valve element are arranged in series with each other in the axial direction of the valve element. . Therefore, the distance between the valve element and the cam must be larger than the outer diameter of the roller. Therefore, when this structure is applied to an OHC or DOHC type engine,
As the height of the valve train increases, the height of the engine must also increase.

On the other hand, in the case of the engine valve train described in Japanese Utility Model Application Laid-Open No. 4-44405, the distance between the valve body and the cam can be reduced to reduce the height of the engine, but on the other hand, thrust rolling. Since the surface of the bearing and the outer peripheral surface of the cam come into sliding contact with each other, friction loss at the contact portion between the surface of the thrust rolling bearing and the outer peripheral surface of the cam increases. As a result, the output of the engine and the fuel efficiency are reduced, which is not preferable. In view of such circumstances, the valve operating mechanism of the engine of the present invention has been invented to reduce the height dimension while sufficiently securing the output and fuel efficiency of the engine.

[0008]

SUMMARY OF THE INVENTION An engine valve operating apparatus according to the present invention is disclosed in Japanese Utility Model Laid-Open Publication Nos. 62-152002 and 63-22306. Similarly to the valve device, a valve lifter that reciprocates in synchronization with a valve body that opens and closes a port communicating with a combustion chamber of the engine, a roller rotatably supported around a pivot supported by the valve lifter, and a crank of the engine. A cam supported by a camshaft rotating in synchronization with the shaft and rotating together with the camshaft, and a valve spring for applying elasticity to the valve body in a direction to close a port communicating with the combustion chamber are provided. Then, by bringing the outer peripheral surface of the cam into contact with the outer peripheral surface of the roller, the valve body is reciprocated in synchronization with the rotation of the crankshaft. In particular, in the engine valve gear of the present invention, a pair of the rollers is provided at intervals in the axial direction of the pivot, and the valve body is provided with the pair of rollers at an intermediate portion of the pivot. It can be freely pressed by the intermediate portion.

[0009]

In the engine valve operating apparatus of the present invention constructed as described above, a part of a pair of rollers and a part of a valve body are pivotally supported by the pair of rollers. By arranging them so as to overlap in the axial direction of the pivot, the height of the valve element in the axial direction can be reduced. Therefore, it is possible to reduce the size and weight of a valve train incorporating a roller and an engine incorporating the valve train for the purpose of reducing frictional force.

[0010]

1 and 2 show a first embodiment of the present invention. For example, a cylinder-shaped valve guide 2 made of a harder metal is inserted into a cylinder head 1 of an engine made of an aluminum alloy, and a valve stem 4 constituting a valve body 3 is provided inside the valve guide 2. 1, the vertical direction depends on the drawing. For example, in the case of a valve operating mechanism installed in a horizontally opposed engine or the like, the vertical direction between the installed state and the state shown in the drawing does not match. It is slidably inserted. The valve element 3 is a so-called mushroom valve, and opens and closes an intake port (exhaust port) 6 by a valve section 5 provided at a lower end of the valve stem 4 based on sliding of the valve stem 4.
A valve guide seal 7 is provided at the upper end of the valve guide 2, and the intake port (exhaust port) 6 is formed through a gap between the inner peripheral surface of the valve guide 2 and the outer peripheral surface of the valve stem 4. It prevents the flowing mixture (exhaust) from leaking to the outside.

A spring seat 9 is supported at the base end of the valve stem 4 through a cotter 8. A valve spring 10, which is a compression coil spring, is provided between the spring seat 9 and the cylinder head 1. Is provided.
Therefore, the valve portion 5 of the valve body 3 is provided with no external force.
The intake port (exhaust port) 6 is kept closed.

Further, a guide hole 11 is formed in a part of the cylinder head 1 opposite to the intake port (exhaust port) 6 with respect to the valve guide 2. This guide hole 1
1 is formed substantially concentrically with the valve stem 4. Then, the valve lifter 12 is inserted into the guide hole 11,
It is fitted so that it can be displaced in the axial direction. The valve lifter 12 is formed in a cylindrical shape from a light metal such as an aluminum alloy, and rotatably supports a pair of rollers 14 at an intermediate portion of a pivot 13 supported at an upper portion.

The valve lifter 12 has a cylindrical outer peripheral surface. Also, on the inner peripheral surface of the upper half,
By forming the pair of flat surfaces 15, 15, the shape of the inner peripheral surface of the upper half is substantially oval. In a portion of the valve lifter 12 corresponding to the widthwise central portion of each of the flat surfaces 15, 15, cutouts 16, 16 which are long U-shaped and are opened at the upper edge of the valve lifter 12 are formed. . Both ends of the pivot 13 are supported and fixed to the notches 16. This pivot 13
It is made of a hard metal such as a bearing steel, and its both ends are fitted into the inner ends of the notches 16, 16.
By caulking a part of each of the notches 16, 16 at the both ends, the valve lifter 12 is fixed in the diametrical direction inside the upper portion of the valve lifter 12.

The pivot 13 has a small diameter portion 17, 17 having a cylindrical outer peripheral surface except for the central portion.
The large-diameter portion 18 has a cylindrical outer peripheral surface. A flat surface 19 is formed in a part of the large diameter portion 18. The pivot 13 supports and fixes the valve lifter 12 with the flat surface 19 facing the upper end surface of the valve stem 4. ing. The rollers 14, 14 are respectively provided between the large diameter portion 18 and the flat surfaces 15, 15 formed on the inner peripheral surface of the valve lifter 12 at two intermediate portions of the pivot 13. Radial needle bearing 2
It is rotatably supported via 0 and 20.

As described above, at the center of the pivot 13 supporting the rollers 14 at two intermediate positions, a flat surface 19 constituting the lower surface of the large diameter portion 18 is provided with the valve stem 4. The upper end surface is in contact. Further, the upper end surfaces of the rollers 14, 14 while being supported by the pivot 13,
It is located slightly below the upper edge of the valve lifter 12. Therefore, in a state where the outer peripheral surface of the cam 21 supported on the outer peripheral surface of the camshaft (not shown) and rotating together with the camshaft is brought into contact with the outer peripheral surfaces of the rollers 14, both ends in the axial direction of the cam 21 A part of the surface engages with the flat surfaces 15 formed on the inner peripheral surface of the valve lifter 12. Then, based on this engagement, the valve lifter 12 does not rotate inside the guide groove 11. In this state, the pivot 13 and the camshaft are parallel. Therefore, the outer peripheral surface of the cam 21 and the outer peripheral surfaces of the rollers 14 are in rolling contact with each other while being in line contact. Therefore, neither excessive surface pressure acts on the contact portion nor large frictional resistance acts on the contact portion.

The valve 3 is reciprocated in the axial direction by the engine valve operating apparatus of the present invention constructed as described above, and the supply port (exhaust port) 6 is controlled by the valve portion 5 of the valve 3. The operation at the time of opening and closing is as follows. That is, during operation of the engine, the cam 2 rotates together with a camshaft (not shown).
The amount of pressing of the pair of rollers 14, 14 by the cam 21 changes based on the eccentric movement of the outer peripheral surface of the roller 1. The outer peripheral surface of each of the rollers 14 is
At the moment when the roller 14 faces the large-diameter portion, each of these rollers 14,
The valve 3 is lowered via the valve shaft 14 and the pivot 13 against the elasticity of the valve spring 10 to open the air supply port (exhaust port) 6. In contrast, each of these rollers 1
At the moment when the outer peripheral surfaces of 4 and 14 face the small diameter portion of the cam 21, the valve 3 rises by the elasticity of the valve spring 10 and closes the air supply port (exhaust port) 6.
The valve clearance is adjusted by the position of the flat surface 19 formed on a part of the pivot 13 (the distance from the center of the pivot 13 to the flat surface 19).

In particular, in the case of the engine valve gear of the present invention, a part of the pair of rollers 14, ie, a part projecting below the pivot 13, and a part of the valve body 3. That is, the upper end of the valve stem 4 is disposed so as to overlap the axial direction of the pivot 13 that supports the pair of rollers 14, 14. Therefore, the above-mentioned actual
As described in JP-A Nos. 2-152002 and 63-22306, the outer peripheral surface of the cam 21 and the upper end surface of the valve stem 4 are connected to the rollers 14 and 14.
It is not necessary to separate the outer diameter from the outside diameter. As a result, the height of the valve operating device of the engine in the axial direction of the valve body 3 can be reduced. Therefore, the roller 1 is used for the purpose of reducing the frictional force.
The valve train incorporating the valve trains 4 and 14 and the engine incorporating the valve train can be reduced in size and weight.

Next, FIGS. 3 and 4 show a second example of the embodiment of the present invention. In the case of this example, a pair of rollers 1
The pivot 13a for rotatably supporting the shafts 4 and 14 is formed in a simple straight rod shape whose diameter does not change over its entire length. Then, both ends of this pivot 13a are formed in circular holes 2 formed at positions opposite to the upper diameter direction of the valve lifter 12a.
A part of each of the circular holes 22, 22 is supported and fixed inside the second and second 22, for example, by caulking toward the outer peripheral surface of the pivot 13a. At the center of the pivot 13a, which is supported and fixed to the valve lifter 12a in this way, a striking member 23 for striking the upper end surface of the valve stem 4 is externally fixed by caulking or the like. The outer peripheral surface of the abutting member 23 is partially flat like the outer peripheral surface of the large-diameter portion 18 formed at the center of the pivot 13 in the first example.
9a. And the above-mentioned pivot 1
3a to the valve lifter 12a,
3 is fixed to the pivot 13a, the flat surface 19a is directed downward, and the flat surface 19a is brought into contact with the upper end surface of the valve stem 4. The valve clearance is adjusted by the position of the flat surface 19a at a part of the abutting member 23 (the thickness of the abutting member 23 at the flat surface 19a). Other configurations and operations are the same as in the case of the above-described first example.

[0019]

The valve train of the engine according to the present invention is constructed and operates as described above. Therefore, the length of the valve body in the axial direction is reduced, and rollers are incorporated for the purpose of reducing the frictional force. The valve gear and the engine incorporating the valve gear can be reduced in size and weight.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a view in which a part is omitted and viewed from above in FIG. 1;

FIG. 3 is a longitudinal sectional view showing a second example of the embodiment of the present invention.

FIG. 4 is a view in which a part is omitted and viewed from above in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Valve guide 3 Valve body 4 Valve stem 5 Valve part 6 Inlet (exhaust port) 7 Valve guide seal 8 Cotta 9 Spring seat 10 Valve spring 11 Guide hole 12, 12a Valve lifter 13, 13a Axis 14 Roller 15 Flat surface 16 Notch 17 Small Diameter Portion 18 Large Diameter Portion 19, 19a Flat Surface 20 Radial Needle Bearing 21 Cam 22 Circular Hole 23 Abutment Member

Claims (1)

[Claims] 1. A valve lifter which reciprocates in synchronism with a valve body which opens and closes an opening communicating with a combustion chamber of an engine, a roller rotatably supported around a pivot supported by the valve lifter, and a crankshaft of the engine. A cam supported by a camshaft that rotates in synchronization with the camshaft and rotating together with the camshaft; and a valve spring for applying an elastic force to the valve body in a direction to close a port that communicates with the combustion chamber. And the outer peripheral surface of the roller by abutting the valve body to reciprocate the valve body in synchronization with the rotation of the crankshaft. A valve train for an engine, characterized in that the valve body is freely pressable by a portion between the pair of rollers at an intermediate portion of the pivot. .