JP2019007468A - Engine, valve guide, and manufacturing method for the valve guide - Google Patents

Abstract

To provide an engine capable of suppressing the agglutination of a valve stem into a valve guide, and to provide the valve guide, and a manufacturing method for the valve guide.SOLUTION: A slide guide surface 3a includes an in-tip guide face 6a provided in a tip 6 out of the tip 6 on the side of a port 1 of a valve guide 3, a base end 8 on the opposite side thereto and an intermediate 7 therebetween, in-utmost-tip guide faces 6α provided nearer a tip end 6c than the in-tip guide face 6a, and an in-base-end guide face 8a provided in the base end 8. An in-guide recessed part 3b includes in-tip recessed portions 6b provided in the tip 6 of the valve guide 3. The in-tip recessed portions 6b are plurally arranged in the valve guide 3 at predetermined spaces held in the peripheral direction, and opened to the port 1. The in-utmost-tip guide faces 6α are provided between the in-tip recessed portions 6b, 6b adjacent to each other in the peripheral direction and plurally arranged in the peripheral direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine, and more particularly to an engine, a valve guide, and a method for manufacturing the valve guide that can suppress sticking of a valve shaft in the valve guide.

  Conventionally, there is an engine including a poppet valve that opens and closes a valve port of an exhaust port and a cylindrical valve guide that guides the reciprocation of the poppet valve (see Patent Document 1).

  This type of engine has an advantage that the reciprocating motion of the poppet valve can be smoothly guided by the valve guide.

  In the invention of Patent Document 1, the inner periphery of the valve guide is provided with an inner guide surface in the distal end portion that guides the valve shaft of the poppet valve in the distal end portion on the port side of the valve guide.

Japanese Utility Model Publication No. 58-86411 (see drawing)

<Problem> There is a risk that the valve stem will stick in the valve guide.
In the invention of Patent Document 1, if carbides of the fuel in the exhaust gas are formed on the surface of the valve shaft, the carbides may bite into the guide surface in the tip portion and the valve shaft may become stuck in the valve guide.

  The subject of this invention is providing the manufacturing method of the engine which can suppress the sticking of the valve shaft in a valve guide, a valve guide, and a valve guide.

(Invention-specific matters of the invention of claim 1)
As illustrated in FIG. 1 (A) or FIG. 2 (A), a poppet valve (2) for opening and closing a valve port (1a) of at least one port (1) for exhaust and intake, and the poppet valve (2) An engine provided with a cylindrical valve guide (3) for guiding the reciprocating motion of the cylinder, a guide insertion hole (4) into which the valve guide (3) is inserted, and a cylinder head (5) having the port (1). In
As illustrated in FIG. 1 (A) or FIG. 2 (A), the valve guide (3) has a sliding guide surface (3a) for guiding the valve shaft (2a) of the poppet valve (2) on its inner periphery. And an in-guide recessed portion (3b) that is recessed radially outward of the valve guide (3) from the sliding guide surface (3a),
The sliding guide surface (3a) includes a distal end portion (6) on the port (1) side of the valve guide (3), a proximal end portion (8) on the opposite side, and an intermediate portion (7) between them. A guide surface (6a) provided in the distal end portion (6), a guide surface (6α) located in the distal end portion closer to the distal end (6c) than the guide surface (6a) in the distal end portion, and a proximal end portion (8) provided with a proximal end guide surface (8a) provided on
The guide recess (3b) includes a tip recess (6b) provided at the tip (6) of the valve guide (3).
As illustrated in FIG. 1 (B) or FIG. 2 (B), a plurality of recessed portions (6b) in the distal end portion are arranged at predetermined intervals in the circumferential direction in the valve guide (3), and the port (1) The leading edge inner guide surface (6α) is provided between the tip inner recessed portions (6b) and (6b) adjacent in the circumferential direction, and a plurality of the guide surfaces are arranged in the circumferential direction. An engine characterized by

(Invention specific matter of invention of claim 13)
A valve guide for use in the engine according to any one of claims 1 to 12, comprising the configuration of the valve guide (3) according to claim 1.

(Invention specific matter of invention of claim 14)
A method for manufacturing a valve guide according to claim 13,
As illustrated in FIG. 3 or FIG. 4, in manufacturing the valve guide (3) by sintering metal powder (9),
Using the resin core (10) that forms the inner periphery of the valve guide (3) during the molding of the metal powder (9), the resin core (10) is removed by the heat during sintering of the metal powder (9). A method for producing a valve guide, wherein the resin core (10) is removed from the sintered product of the valve guide (3) by melting or pyrolyzing.

(Invention according to Claim 1 or Claim 13)
The invention according to claim 1 or claim 13 has the following effects.
<< Effect >> Sticking of the valve shaft (2a) in the valve guide (3) can be suppressed.
As illustrated in FIG. 1 (A) or FIG. 2 (A), even if unburned fuel in exhaust, blowby gas or EGR gas in intake air becomes carbide on the surface of the valve shaft (2a), The carbide on the surface of the shaft (2a) is scraped off at the edge of the tip (6c) of the valve guide (3) by sliding the valve shaft (2a) in the valve closing direction, and the valve shaft (2a) Due to the rotation, it is scraped off at the edge of the indented portion (6b) in the tip, and the carbide is difficult to bite into the guide surface (6a) in the tip and the inner guide surface (6α) in the tip, and the valve in the valve guide (3) Sticking of the shaft (2a) can be suppressed.

<Effect> Heat dissipation of the valve shaft (2a) is promoted.
As illustrated in FIG. 1 (A) or FIG. 2 (A), the sliding heat of the valve shaft (2a) generated in the valve guide (3) is caused by a plurality of guide surfaces (6α) in the most distal portion and in the tip portion. Heat is efficiently radiated from the valve guide (3) to the cylinder head (5) through a wide heat radiating area composed of the guide surface (6a) and the base end inner guide surface (8a), and heat dissipation of the valve shaft (2a) is promoted. .
<Effect> Heat dissipation of the valve shaft (2a) is promoted.
As shown in FIG. 1 (A), even if the sliding heat of the valve shaft (2a) is dissipated to the exhaust or intake air in the recessed portion (6b) in the tip, the exhaust or intake air that has become hot due to the heat dissipation The convection replaces the relatively low temperature exhaust or intake air in the port (1), and heat dissipation of the valve shaft (2a) is promoted.

(Invention of Claim 14)
The invention according to claim 14 has the following effects.
<Effect> It is possible to easily remove the resin core (10) having a convex portion on the outer periphery.
As illustrated in FIG. 3 or FIG. 4, the resin core (10) having a convex portion on the outer periphery can be easily removed from the sintered product of the valve guide (3).

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the engine which concerns on 1st Embodiment of this invention, FIG. 1 (A) is a principal part longitudinal cross-sectional view of an engine, FIG.1 (B) is a BB sectional drawing of FIG. 1 (C) is a cross-sectional view taken along line CC of FIG. 1 (A). 2A and 2B are views for explaining an engine according to a second embodiment of the present invention. FIG. 2A is a longitudinal sectional view of a main part of the engine, FIG. 2B is a sectional view taken along line BB in FIG. 2 (C) is a cross-sectional view taken along line CC of FIG. 2 (A). It is a figure explaining embodiment of the manufacturing method of the valve guide used with the engine of FIG. It is a figure explaining embodiment of the manufacturing method of the valve guide used with the engine of FIG.

  1 is an engine according to a first embodiment of the present invention, FIG. 2 is an engine according to a second embodiment, FIG. 3 is a method of manufacturing a valve guide used in the engine of FIG. 1, and FIG. 4 is a valve used in the engine of FIG. In the drawings for explaining a guide manufacturing method, each embodiment will explain a vertical diesel engine and a valve guide manufacturing method used in the engine.

First, the engine according to the first embodiment will be described.
As shown in FIG. 1A, this vertical diesel engine includes a poppet valve (2) for opening and closing a valve port (1a) of an exhaust (and intake) port (1), and a poppet valve (2). A valve guide (3) that guides reciprocation, a guide insertion hole (4) into which the valve guide (3) is inserted, and a cylinder head (5) having the port (1) are provided.
This type of engine has an advantage that the reciprocating motion of the poppet valve (2) can be smoothly guided by the valve guide (3).
In this embodiment, the exhaust port and the intake port have the same structure. In the following description, unless otherwise specified, the port (1) means both the exhaust port and the intake port.

As shown in FIG. 1A, the poppet valve (2) includes a valve shaft (2a) and a valve head (2c).
An annular valve seat (1f) is fitted into the open end of the port (1), and a valve port (1a) is opened in the valve seat (1f).
This engine includes a spring retainer (11) attached to a valve shaft (2a) of a poppet valve (2), and a valve disposed between the spring retainer (11) and a spring seat (5b) of a cylinder head (5). A spring (12), a rocker arm (13) in contact with the valve shaft (2a), and a valve shaft seal (14) externally fitted to the proximal end (8b) of the valve guide (3) are provided. 12) With the urging force of 12), the valve face (2d) of the valve head (2c) is seated on the valve seat (1f), and the urging force of the valve spring (12) is resisted by the pressing force of the rocker arm (13). The poppet valve (2) is lowered and the poppet valve (2) is opened.

)
The configuration of the valve guide (3) is as follows.
As shown in FIG. 1 (A), the valve guide (3) has, on its inner periphery, a sliding guide surface (3a) for guiding the valve shaft (2a) of the poppet valve (2), and this sliding guide surface. An in-guide recess (3b) is provided that is recessed radially outward of the valve guide (3) relative to (3a).
The recessed portion (3b) in the guide is composed of a tip (6) on the port (1) side of the valve guide (3), a base end (8) on the opposite side, and an intermediate portion (7) between them. The tip end portion recessed portion (6b) is provided at the tip end portion (6).

  The sliding guide surface (3a) is provided closer to the distal end (6c) than the inner guide surface (6a) at the distal end portion provided at the distal end portion (6) of the valve guide (3). In addition, a guide surface (6α) in the most distal portion and a guide surface (8a) in the base end portion provided in the base end portion (8) are provided.

As shown in FIG. 1 (B), a plurality of recessed portions (6b) in the distal end portion are arranged at predetermined intervals in the circumferential direction in the valve guide (3), and the innermost guide portion (6α) Provided between the recessed portions (6b) and (6b) in the front end adjacent to each other in the circumferential direction, a plurality of them are arranged in the circumferential direction.
Both the distal end inner guide surface (6a) and the proximal end inner guide surface (8a) guide the entire circumference of the valve shaft (2a).

  For this reason, in this embodiment, as shown in FIG. 1A, even if the components of the unburned fuel in the exhaust, the blowby gas in the intake air, and the EGR gas become carbide on the surface of the valve shaft (2a), The carbide on the surface of the valve shaft (2a) is scraped off at the edge of the tip (6c) of the valve guide (3) by sliding the valve shaft (2a) in the valve closing direction, and the valve shaft (2a). Is scraped off at the edge of the recessed portion (6b) in the distal end portion, and the carbide is difficult to bite into the inner guide surface (6a) and the innermost guide surface (6α) in the distal end portion, and in the valve guide (3). Sticking of the valve shaft (2a) can be suppressed.

In addition, as shown in FIG. 1A, even if the sliding heat of the valve shaft (2a) is radiated to the exhaust or intake air in the indented portion (6b) in the tip, the exhaust or The intake air is replaced by relatively low temperature exhaust or intake air in the port (1) by convection, and heat dissipation of the valve shaft (2a) is promoted.
Further, as shown in FIG. 1 (A) or FIG. 2 (A), the sliding heat of the valve shaft (2a) generated in the valve guide (3) is caused by a plurality of leading edge inner guide surfaces (6α) and tips. Heat is efficiently radiated from the valve guide (3) to the cylinder head (5) through a wide heat radiation area consisting of the inner guide surface (6a) and the proximal end inner guide surface (8a), and the heat release of the valve shaft (2a) is promoted. The

As shown in FIG. 1 (A), the distal end inner guide surface (6a) and the proximal end inner guide surface (8a) both guide the entire circumference of the valve shaft (2a). The distal end and the proximal end of the intermediate recessed portions (7b) and (7b) are respectively closed by the wall surfaces of the distal end inner guide surface (6a) and the proximal end inner guide surface (8a).
The axial direction of the valve guide (3) is directed in the vertical direction, the upper side is the base end (8) of the valve guide (3), and the lower side is the front end (6) of the valve guide (3). Yes.

As shown in FIG. 1 (A), the guide recess (3b) includes an intermediate recess (7b) provided in the intermediate portion (7) of the valve guide (3).
For this reason, in this embodiment, as shown in FIG. 1 (A), the components of unburned fuel in exhaust, blowby gas and EGR gas in intake air in the tip (6) of the valve guide (3) are carbides. Even in this case, the carbide is discharged to the plurality of intermediate inner recessed portions (7b), and the carbide is difficult to bite into the distal end inner guide surface (6a) and the intermediate inner guide surface (7a). The sticking of the valve shaft (2a) is suppressed.

As shown in FIG. 1 (A), the intermediate portion (7) of the valve guide (3) provided with the intermediate inner recessed portion (7b) is fitted in the guide insertion hole (4).
For this reason, in this embodiment, as shown in FIGS. 1 (A) and 1 (B), the heat of carbide in the recessed portion (7b) in the intermediate portion that receives the sliding heat of the valve shaft (2a) is transferred to the intermediate portion ( The heat is dissipated from the valve guide (3) to the cylinder head (5) via 7), and the heat dissipation of the carbide is promoted.

As shown in FIG. 1 (A), the intermediate part (7) in which the intermediate part recessed part (7b) is provided is in close contact with the inner peripheral surface of the guide insertion hole (4).
For this reason, in this embodiment, as shown in FIG. 1 (A), the heat of the carbide in the recessed portion (7b) in the intermediate portion is transferred from the outer peripheral surface of the intermediate portion (7) to the inner periphery of the guide insertion hole (4). Heat is radiated to the cylinder head (5) through the surface, and the heat dissipation efficiency of the carbide is high.

As shown in FIG. 1 (A), the cylinder head (5) includes a water jacket (5a) that allows engine coolant to pass therethrough.
For this reason, in this embodiment, as shown in FIG. 1 (A), the heat of the carbide in the intermediate recessed portion (7b) is strongly cooled by the engine coolant passing through the water jacket (5a). Heat is released to the cylinder head (5), and the heat dissipation efficiency of carbide is high.

As shown in FIGS. 1 (A) and 1 (B), the intermediate inner recessed portion (7b) is formed in an annular shape.
For this reason, in this embodiment, as shown in FIGS. 1 (A) and 1 (B), a large amount of carbide is accommodated in the annular intermediate recess portion (7b).

  As shown in FIG. 1 (A), the tip (6) of the valve guide (3) is fitted into the guide insertion hole (4), and the inner peripheral surface of the guide insertion hole (4) and the valve guide (3). Between the outer peripheral surfaces of the front end portion (6), an outer end end clearance (4a) that opens toward the port (1) is formed.

  Therefore, in this embodiment, as shown in FIG. 1 (A), the sliding heat of the valve shaft (2a) is radiated to the exhaust and intake air in the outer clearance (4a) at the tip end portion via the valve guide (3). Even so, exhaust and intake air that have become hot due to heat dissipation are replaced by relatively low temperature exhaust and intake air in the port (1) by convection, and heat dissipation of the valve shaft (2a) is promoted.

As shown in FIG. 1A, the outer peripheral surface of the exposed valve shaft portion (2b) of the poppet valve (2) exposed in the port (1) when the poppet valve (2) is fully opened is formed without a step. .
The outer peripheral surface of the exposed valve shaft portion (2b) of the poppet valve (2) has a single diameter.

  For this reason, in this embodiment, when the poppet valve (2) is fully opened, it is formed on the outer peripheral surface of the exposed valve shaft portion (2b) of the poppet valve (2) that receives collision of exhaust or intake air that passes through the port (1) at high speed. In addition, a corner portion due to a step that causes stress concentration or a heat point is not formed, and damage to the poppet valve (2) due to collision of exhaust or intake air is suppressed.

  As shown in FIG. 1 (A), the port (1) has an in-port recessed portion (1c) in which the port inner surface (1b) is recessed toward the port side opening (4b) of the guide insertion hole (4). The tip (6c) of the valve guide (3) faces the recessed portion (1c) in the port.

  For this reason, in this embodiment, as shown in FIG. 1 (A), the exhaust or intake air that passes through the port (1) hardly collides with the tip (6) of the valve guide (3), and the valve guide (3). Generation of carbide in the tip portion (6) of the steel is suppressed.

  As shown in FIG. 1 (C), when viewed in a direction parallel to the central axis (3c) of the valve guide (3), the inner periphery of the in-port recessed portion (1c) is the inner periphery of the guide insertion hole (4). The entire guide insertion hole (4), the entire distal end (6c) of the valve guide (3), and the entire distal end opening (6d) of the recessed portion (6b) in the distal end are all It faces the recessed part (1c) in the port.

As shown in FIG. 1 (A), the tip (6c) of the valve guide (3) faces the recessed portion (1c) in the port from the inside of the guide insertion hole (4).
For this reason, in this embodiment, as shown in FIG. 1 (A), the exhaust or intake air that passes through the port (1) is less likely to collide with the tip (6) of the valve guide (3).

As shown in FIG. 1 (A), the port (1) has a boss (1e) protruding into the port (1) from the inner peripheral surface (1d) of the port wall at a position where the guide insertion hole (4) is provided. And an in-port recessed portion (1c) into which the protruding end surface (1g) of the boss (1e) is recessed.
For this reason, in this embodiment, as shown in FIG. 1A, exhaust and intake air flowing in the port (1) along the inner peripheral surface (1d) of the port wall are guided by the outer peripheral surface of the boss (1e). The exhaust and intake air move away from the tip (6) of the valve guide (3).

As shown in FIG. 1A, the port (1) includes a tangential intake port, and the in-port recessed portion (1c) is provided in the tangential intake port.
A tangential intake port refers to an intake port oriented in the tangential direction of the cylinder when viewed in a direction parallel to the cylinder central axis.

  Compared with the swirl port, the tangential port with a large intake flow rate at the center of the port has a large amount of intake air including blowby gas and EGR gas passing through the tip (6) of the valve guide (3). Although there is a tendency that carbide is likely to be generated in the distal end portion (6), in this embodiment, a structure in which intake air does not easily collide with the distal end portion (6) of the valve guide (3) is adopted. The generation of carbides is significantly reduced, and the function of suppressing the generation of carbides in the tip (6) of the valve guide (3) becomes obvious.

As shown in FIG. 2 (B), a plurality of intermediate inner recessed portions (7b) are arranged at predetermined intervals in the circumferential direction in the valve guide (3), and the intermediate inner guide surface (7a) It is provided between the intermediate inward recessed portions (7b) and (7b) adjacent to each other in the direction, and a plurality of them are arranged in the circumferential direction.
For this reason, in this embodiment, as shown in FIG. 2 (B), even if the components of the unburned fuel in the exhaust, the blow-by gas in the intake air, and the EGR gas become carbide on the surface of the valve shaft (2a), The carbide on the surface of the valve shaft (2a) is scraped off at the edge of the intermediate inner recessed portion (7b) by the rotation of the valve shaft (2a), and the carbide is difficult to bite into the intermediate inner guide surface (7a). Sticking of the valve shaft (2a) in the guide (3) can be suppressed.
Further, as shown in FIG. 2B, the sliding heat of the valve shaft (2a) generated in the valve guide (3) is caused to flow through a wide heat radiation area composed of a plurality of intermediate inner guide surfaces (7a). Heat is efficiently radiated from the guide (3) to the cylinder head (5), and heat radiation of the valve shaft (2a) is promoted.

Next, an engine according to a second embodiment shown in FIG. 2 will be described.
As shown in FIG. 2 (A), a plurality of recesses (7b) in the intermediate part are arranged at predetermined intervals in the vertical direction, which is the axial length direction in the valve guide (3). 7a) is also provided between the intermediate inner recessed portions (7b) (7b) adjacent in the vertical direction, and a plurality of them are also arranged in the vertical direction.

  For this reason, in this embodiment, as shown in FIG. 2 (A), the carbide that has floated along the guide surface (6a) inside the tip from the tip (6) of the valve guide (3) From the recessed portion (7b), the surface gradually rises to the upper intermediate recessed portion (7b), and is gradually dispersed and collected in the plurality of intermediate recessed portions (7b), and is loaded on the inner guide surface (6a) by the carbide load. The rising of the carbides along the line is not hindered, and the discharge of the carbides into the recessed part (7b) in the intermediate part is promoted.

  Further, as shown in FIG. 2 (A), high-temperature exhaust that tries to blow upward from the port (1) into the valve guide (3), or intake air containing high-temperature blowby gas or EGR gas, A plurality of intermediate inner guide surfaces (7a) arranged in the direction are throttled to suppress exhaust and intake air blow-through in the valve guide (3).

  The configurations and functions other than the above-described configurations and functions are the same as those of the first embodiment described in FIGS. 1A to 1C, and in FIGS. The same elements are denoted by the same reference numerals as in FIGS.

Next, an embodiment of a method for manufacturing the valve guide (3) used in the engine according to the first embodiment shown in FIG. 1 will be described.
As shown in FIG. 3, in this manufacturing method, when the valve guide (3) is manufactured by sintering the metal powder (9), the inner periphery of the valve guide (3) is formed when the metal powder (9) is formed. A resin core (10) is used.
Next, the resin core (10) is melted or thermally decomposed by heat during sintering of the metal powder (9), and the resin core (10) is removed from the sintered product of the valve guide (3). .

  For this reason, in this embodiment, as shown in FIG. 3, the resin core (10) having a convex portion on the outer periphery is easily removed from the sintered product of the valve guide (3).

An iron-based sintered metal material is used for the metal powder (9).
The metal powder (9) is molded by press molding using a mold (15). The die (15) includes a die (15c) having a cavity (15a) for filling the metal powder (9), a supply port (15b) for supplying the metal powder (9) to the cavity (15a), and a die (15c). The upper and lower punches (15d) and (15e) move up and down inside.
For the resin core (10), a thermoplastic resin such as nylon or a thermosetting resin such as phenol resin can be used.
When a thermoplastic resin is used for the resin core (10), the resin core (10) is removed from the sintered product of the valve guide (3) by melting.
When a thermosetting resin is used for the resin core (10), the resin core (10) is removed from the sintered product of the valve guide (3) by thermal decomposition.
A resin core (10) reinforced with fibers such as glass fibers is used.
On the outer periphery of the resin core (10), in the order from the distal end side, a recessed portion (6b) in the distal end portion, a guide surface in the distal end portion (6a), a recessed portion in the intermediate portion (7b), and a guide surface in the proximal end portion (8a) Concavities and convexities for forming are formed.

FIG. 4 shows an embodiment of a method for manufacturing a valve guide used in the engine according to the second embodiment shown in FIG.
As shown in FIG. 4, this manufacturing method and effects are also the same as the manufacturing method shown in FIG.
4, the same elements as those in FIG. 3 are denoted by the same reference numerals as those in FIG. 3.
On the outer periphery of the resin core (10), in order from the front end side, the inner recessed portion (6b), the inner guide surface (6a), the three inner recessed portions (7b), and the intermediate inner guide surface ( 7a), irregularities for forming the proximal end guide surface (8a) are formed.

(1) ... Port, (1a) ... Valve, (1b) ... Port inner surface, (1c) ... Recessed portion in port, (1d) ... Port wall inner peripheral surface, (1e) ... Boss, (1g) ... Projection End face, (2) ... Poppet valve, (3) ... Valve guide, (3a) ... Sliding guide face, (3b) ... Guide recess in guide, (4) ... Guide insertion hole, (4a) ... Gap outside tip (5) ... Cylinder head, (6) ... Tip, (6a) ... Guide surface in tip, (6α) ... Guide surface in tip, (6b) ... Recess in tip, (6c) ... Tip, ( 7) ... intermediate part, (7a) ... guide part in the intermediate part, (7b) ... concave part in the intermediate part, (8) ... base end part, (8a) ... guide surface in the base end part, (8b) ... base end, ( 9) Metal powder, (10) Resin core.

Claims (14)

A poppet valve (2) for opening and closing the valve port (1a) of at least one of the exhaust and intake ports (1), a cylindrical valve guide (3) for guiding the reciprocating motion of the poppet valve (2), In an engine comprising a guide insertion hole (4) into which a valve guide (3) is inserted and a cylinder head (5) having the port (1),
The valve guide (3) has a sliding guide surface (3a) for guiding the valve shaft (2a) of the poppet valve (2) on the inner periphery thereof, and the valve guide (3) than the sliding guide surface (3a). A guide recessed portion (3b) recessed radially outward of the guide,
The sliding guide surface (3a) includes a distal end portion (6) on the port (1) side of the valve guide (3), a proximal end portion (8) on the opposite side, and an intermediate portion (7) between them. A guide surface (6a) provided in the distal end portion (6), a guide surface (6α) located in the distal end portion closer to the distal end (6c) than the guide surface (6a) in the distal end portion, and a proximal end portion (8) provided with a proximal end guide surface (8a) provided on
The guide recess (3b) includes a tip recess (6b) provided at the tip (6) of the valve guide (3).
A plurality of recessed portions (6b) in the distal end portion are arranged at predetermined intervals in the circumferential direction in the valve guide (3), open toward the port (1), and the innermost guide surface (6α) An engine, which is provided between the inwardly inserted inward ends (6b) and (6b) in the circumferential direction, and is arranged in a plurality in the circumferential direction. The engine according to claim 1,
The engine is characterized in that the guide recess (3b) includes an intermediate recess (7b) provided in the intermediate portion (7) of the valve guide (3). The engine according to claim 2,
An engine characterized in that an intermediate portion (7) of a valve guide (3) provided with an intermediate recess portion (7b) is fitted in a guide insertion hole (4). The engine according to claim 2 or claim 3,
The engine characterized in that the recess portion (7b) in the intermediate portion is formed in an annular shape. The engine according to claim 2 or claim 3,
A plurality of intermediate inward recessed portions (7b) are arranged at predetermined intervals in the circumferential direction in the valve guide (3), and the intermediate inner guide surface (7a) is adjacent to the intermediate inward recessed portion (7b) in the circumferential direction. ) And (7b), and the engine is arranged in a plurality in the circumferential direction. The engine according to any one of claims 2 to 5,
A plurality of intermediate inner recessed portions (7b) are arranged at predetermined intervals in the vertical direction which is the axial length direction in the valve guide (3), and the intermediate inner guide surfaces (7a) are adjacent to each other in the vertical direction. An engine characterized in that a plurality of inward recessed portions (7b) (7b) are provided, and a plurality of them are also arranged in the vertical direction. The engine according to any one of claims 1 to 6, wherein
The distal end portion (6) of the valve guide (3) is fitted into the guide insertion hole (4), and the inner peripheral surface of the guide insertion hole (4) and the outer peripheral surface of the distal end portion (6) of the valve guide (3). An engine characterized in that an outer clearance (4a) at the front end that opens toward the port (1) is formed therebetween. The engine according to any one of claims 1 to 7,
An engine characterized in that the outer peripheral surface of the exposed valve shaft portion (2b) of the poppet valve (2) exposed in the port (1) when the poppet valve (2) is fully opened is formed without a step. The engine according to any one of claims 1 to 8,
The port (1) includes an in-port recessed portion (1c) in which the inner surface (1b) of the port is recessed toward the port side opening (4b) of the guide insertion hole (4), and the tip of the valve guide (3) ( An engine characterized in that 6c) faces into a recessed portion (1c) in the port. The engine according to claim 9,
The engine characterized in that the tip (6c) of the valve guide (3) faces the recessed portion (1c) in the port from the inside of the guide insertion hole (4). The engine according to claim 9 or 10,
The port (1) is provided with a boss (1e) projecting into the port (1) from the inner peripheral surface (1d) of the port wall at a position where the guide insertion hole (4) is provided, and a projecting end surface ( An engine comprising an in-port recessed portion (1c) into which 1g) is recessed. The engine according to any one of claims 9 to 11,
The engine characterized in that the port (1) includes a tangential intake port, and the in-port recessed portion (1c) is provided in the tangential intake port. A valve guide for use in the engine according to any one of claims 1 to 12,
The valve guide (3) has a sliding guide surface (3a) for guiding the valve shaft (2a) of the poppet valve (2) on the inner periphery thereof, and the valve guide (3) than the sliding guide surface (3a). A guide recessed portion (3b) recessed radially outward of the guide,
The sliding guide surface (3a) includes a distal end portion (6) on the port (1) side of the valve guide (3), a proximal end portion (8) on the opposite side, and an intermediate portion (7) between them. A guide surface (6a) provided in the distal end portion (6), a guide surface (6α) located in the distal end portion closer to the distal end (6c) than the guide surface (6a) in the distal end portion, and a proximal end portion (8) provided with a proximal end guide surface (8a) provided on
The guide recess (3b) includes a tip recess (6b) provided at the tip (6) of the valve guide (3).
A plurality of recessed portions (6b) in the distal end portion are arranged at predetermined intervals in the circumferential direction in the valve guide (3), open toward the port (1), and the innermost guide surface (6α) A valve guide characterized in that a plurality of circumferentially adjacent tip inner recessed portions (6b) and (6b) are provided, and a plurality of them are arranged in the circumferential direction. A method for manufacturing a valve guide according to claim 13,
In producing the valve guide (3) by sintering metal powder (9),
Using the resin core (10) that forms the inner periphery of the valve guide (3) during the molding of the metal powder (9), the resin core (10) is removed by the heat during sintering of the metal powder (9). A method for producing a valve guide, wherein the resin core (10) is removed from the sintered product of the valve guide (3) by melting or pyrolyzing.

Images