JP2023039209A - valve guide - Google Patents

Abstract

To provide a valve guide capable of preventing sliding failure of a valve caused by intrusion of a combustion product to a valve sliding portion (clearance between valve and valve guide).SOLUTION: A cylindrical valve guide 33 fitted to a cylinder head 20 and guiding reciprocation of a valve 32 includes: a spiral groove 331 spirally formed on an inner peripheral surface along an axial direction; and a vertical groove 332 linearly formed on the inner peripheral surface along the axial direction in a manner of intersecting with the spiral groove 331 at least one end portion and reaching the valve guide 33 at the other end. The spiral groove 331 is formed on an intermediate portion excluding a tip portion and a basic end portion, of the valve guide 33. The vertical groove 332 is formed so as to avoid a direction of oscillation of a valve stem 321 occurring in valve coking.SELECTED DRAWING: Figure 2

Description

The present invention relates to valve guides.

Conventionally, valve guides made of, for example, iron-based sintered alloys, which have wear resistance and lubricity, and guide the reciprocating motion of valves (valve stems) have been used mainly for aluminum alloy cylinder heads. ing. The valve guide is formed in a thin tubular shape so that the valve stem can slide on its inner surface. In addition, such a valve guide is known to have a scraper function to scrape off (remove) combustion products (deposits such as soot) that adhere and accumulate on the valve (for example, Patent Document 1 reference).

JP-A-6-299817

However, for example, if combustion products enter the valve sliding part (the gap between the valve and the valve guide) due to afterfire near the exhaust port, the clearance of the valve sliding part will decrease at high temperatures such as high rotation and high load. When clogged, the entrapment of combustion products can prevent the valve from following the cam profile.

The present invention was made to solve the above-mentioned problems, and prevents valve sliding failure caused by combustion products entering (biting) into the valve sliding portion (the gap between the valve and the valve guide). An object of the present invention is to provide a valve guide capable of

A valve guide according to one aspect of the present invention is a cylindrical valve guide that is fitted to a cylinder head and guides the reciprocating motion of a valve, and is formed on the inner peripheral surface in a helical shape along the axial direction. and a longitudinal groove formed on the inner peripheral surface in a straight line along the axial direction so that at least one end intersects the spiral groove and the other end reaches the tip of the valve guide. and

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to prevent the sliding defect of a valve|bulb by a combustion product entering (biting) into a valve sliding part.

It is a figure which shows the valve mechanism to which the valve guide which concerns on embodiment was applied. It is a sectional view of a valve guide concerning an embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same reference numerals are used for the same or corresponding parts. Further, in each figure, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

First, the configuration of the valve guide 33 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a view showing an exhaust-side valve mechanism (direct-acting valve system) 30 to which a valve guide 33 is applied. FIG. 2 is a cross-sectional view of the valve guide 33. As shown in FIG. In this embodiment, a case where the valve guide 33 is applied to the valve mechanism 30 on the exhaust side will be described as an example.

An intake port and an exhaust port 22 are formed for each cylinder in a cylinder head 20 of the engine (only the exhaust port 22 is shown in FIG. 1). The exhaust port 22 is provided with an exhaust valve (hereinafter also simply referred to as “valve”) 32 for opening and closing the exhaust port 22 .

A valve stem 321 of the exhaust valve 32 is slidably inserted into a through hole of a valve guide 33 fitted to a wall portion above the exhaust port 22 of the cylinder head 20 . A valve seal (stem seal) 37 made of a rubber material or the like is attached to the exposed upper end portion of the valve guide 33 that protrudes toward the valve spring 34 from the fitting portion of the valve guide 33 to the cylinder head 20 . The outer circumference of the shaft of the stem 321 is elastically pressed and sealed.

A retainer 36 is attached to the stem end of the exhaust valve 32 with a cotter pin (valve cotter) 35 . A valve spring seat 38 is provided on the wall surface of the cylinder head 20 facing the retainer 36 , and the valve spring 34 is provided between the valve spring seat 38 and the spring retainer 36 .

The valve spring 34 presses the valve head of the exhaust valve 32 against the valve seat 39 to close the exhaust port 22 , and the upper end surface of the stem end acts as an exhaust cam (hereinafter sometimes simply referred to as “cam”) 31 . is abutted.

When the cam 31 is rotated, the exhaust valve 32 opens and closes along the cam face (cam profile) against the biasing force of the valve spring 34 .

Here, the valve guide 33 is a member that is made of, for example, an iron-based sintered alloy, has wear resistance and lubricity, and guides the reciprocating motion of the valve 32 (valve stem 321). The valve guide 33 is formed in a cylindrical shape, and is press-fitted into the cylinder head 20 with a prescribed press-fit allowance by, for example, normal temperature or cold fitting.

In particular, the valve guide 33 has a function of preventing poor sliding of the valve 32 due to entry (biting) of combustion products into the valve sliding portion (the gap between the valve 32 and the valve guide 33).

Therefore, the valve guide 33 mainly has a spiral groove 331 formed spirally along the axial direction on the inner peripheral surface, and a linear groove 331 formed on the inner peripheral surface along the axial direction (parallel to the axis). A longitudinal groove 332 formed so as to intersect with the spiral groove 331 is provided. The vertical groove 332 is formed such that at least one end thereof intersects with the spiral groove 331 and the other end thereof reaches the tip of the valve guide 33 . Therefore, the combustion products that have entered the valve sliding portion (the gap between the valve 32 and the valve guide 33) are carried from the spiral groove 331 through the longitudinal groove 332 due to the vibration and reciprocating motion of the valve 32, and are transferred to the valve guide 33. discharged to the outside.

Here, the spiral groove 331 is preferably formed in an intermediate portion of the valve guide 33 excluding the distal end and the proximal end in order to prevent the deterioration of the carbon scraper function and the hard contact during valve cocking. That is, it is preferable not to form the spiral groove 331 on the distal end and the proximal end of the valve guide 33 .

In addition, from the viewpoint of protecting the valve stem 321 by preventing it from hitting the valve stem 321 when valve cocking occurs, the longitudinal grooves 332 are formed, for example, at intervals of 180° in the valve cocking direction (Figs. 1 and 2). It is preferable that two grooves are formed so as to be recessed in a direction orthogonal to the left-right direction. That is, the longitudinal groove 332 is preferably formed in a direction that avoids the direction in which the valve stem 321 swings when valve cocking occurs.

In addition, in order to prevent combustion products (foreign matter) that have entered (dropped) into the groove from appearing again on the valve sliding surface, the spiral groove 331 has It is preferable that the groove has a concave shape radially outward (outside) and that the width of the groove increases as it goes radially outward. Similarly, when viewed in a cross section orthogonal to the axial direction, the longitudinal groove 332 has a concave shape radially outward (outside), and the width of the groove increases as it goes radially outward. It is preferably formed as follows. Note that the spiral groove 331 and the vertical groove 332 can be formed (modeled) by, for example, a vanishing core. Moreover, the spiral groove 331 and the vertical groove 332 may be formed by cutting or the like.

Furthermore, in order to allow the combustion products that have entered the valve sliding surface to enter (drop) into the spiral groove 331 more quickly (early), the spiral groove 331 is formed by the winding of the valve spring 34 that biases the valve 32 in the valve closing direction. It is preferably formed so as to draw a spiral in the forward direction (same direction) as the direction. That is, the helical groove 331 is preferably formed so as to draw a spiral in the opposite direction (opposite direction) to the direction in which the valve 32 rotates due to the torsion (deflection) of the valve spring 34 .

With the configuration as described above, that is, on the inner peripheral surface, along the axial direction, a spiral groove 331 and a longitudinal groove 332 intersecting with the spiral groove 331 and reaching the tip of the valve guide 33 are formed. By being formed, combustion products that have entered the valve sliding portion (the gap between the valve 32 and the valve guide 33) are transported from the spiral groove 331 through the vertical groove 332 by the vibration and reciprocating motion of the valve 32, It is discharged outside the valve guide 33 . At that time, combustion products that have entered (fallen) into the spiral groove 331 are discharged through the vertical groove 332 earlier.

As described in detail above, according to the present embodiment, the sliding failure of the valve 32 due to entry (biting) of combustion products into the valve sliding portion (the gap between the valve 32 and the valve guide 33) can be prevented. can be prevented.

As a result, it is possible to prevent a decrease in output and a deterioration in exhaust gas (emission) due to inability to follow the cam profile due to poor sliding. Furthermore, interference between the piston and the valve 32 due to inability to follow the cam profile can be prevented.

According to this embodiment, the spiral groove 331 is formed in the intermediate portion of the valve guide 33 excluding the distal end and the proximal end. That is, the spiral groove 331 is not formed in the distal end and the proximal end of the valve guide 33 . Therefore, it is possible to prevent deterioration of the carbon scraper function and heavy impact during valve cocking.

According to this embodiment, the longitudinal groove 332 is formed so as to be recessed in a direction orthogonal to the valve cocking direction. That is, the longitudinal groove 332 is formed to avoid the direction in which the valve stem 321 swings when valve cocking occurs (valve cocking direction). Therefore, when valve cocking occurs, it is possible to prevent the valve stem 321 from being forced into contact with the valve stem 321, and the valve stem 321 can be protected.

According to this embodiment, the cross sections of the spiral grooves 331 and the vertical grooves 332 are formed so that the cross sections of each groove form a radially outward concave shape, and the width of the grooves increases as it goes radially outward. It is Therefore, combustion products (foreign matter) that have entered (fallen) into the groove can be prevented from reappearing on the valve sliding surface.

According to this embodiment, the spiral groove 331 is formed so as to draw a spiral in the forward direction (the same direction) as the winding direction of the valve spring 34 . That is, the spiral groove 331 is formed so as to draw a spiral in the opposite direction (opposite direction) to the direction in which the valve 32 rotates due to the torsion (deflection) of the valve spring 34 . Therefore, the foreign matter that has entered the valve sliding portion can be quickly dropped into the spiral groove 331 .

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiment, the valve guide 33 is applied to the valve mechanism 30 of the exhaust system, but it may be applied to the valve mechanism of the intake system.

In the above embodiment, the spiral grooves 331 and the vertical grooves 332 are each formed so that the width of the groove increases as it goes radially outward. may

In the above embodiment, two vertical grooves 332 are formed at 180° intervals, but three or more may be formed as long as the valve cocking direction is avoided.

20 cylinder head 22 exhaust port 30 valve mechanism (valve mechanism)
31 exhaust cam 32 exhaust valve 321 valve stem 33 valve guide 331 spiral groove 332 vertical groove 34 valve spring 35 cotter pin 36 retainer 37 valve seal 38 valve spring seat 39 valve seat

Claims (5)

A cylindrical valve guide that is fitted to the cylinder head and guides the reciprocating motion of the valve,
a spiral groove formed spirally along the axial direction on the inner peripheral surface;
a longitudinal groove formed on the inner peripheral surface in a straight line along the axial direction so that at least one end intersects the spiral groove and the other end reaches the tip of the valve guide; A valve guide, comprising: 2. The valve guide according to claim 1, wherein the spiral groove is formed in an intermediate portion of the valve guide excluding a distal end portion and a proximal end portion. 3. The valve guide according to claim 1, wherein the longitudinal groove is formed to avoid a direction in which the valve stem swings when valve cocking occurs. The spiral groove is formed so that when viewed in a longitudinal section along the axial direction, it has a concave shape radially outward, and the width of the groove increases as it goes radially outward. ,
The vertical groove is formed so that when viewed in a cross section perpendicular to the axial direction, it has a concave shape radially outward, and the width of the groove increases as it goes radially outward. The valve guide according to any one of claims 1 to 3, characterized in that: 5. The spiral groove according to any one of claims 1 to 4, wherein the spiral groove is formed so as to draw a spiral in the same direction as the winding direction of a valve spring that biases the valve in the valve closing direction. Valve guide as described.

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