JPH0240470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a valve seat grinding tool used for maintenance of intake and exhaust valves of internal combustion engines.

<Prior Art> Conventionally, as this type of valve seat grinding tool, one shown in FIG. 7, for example, is known. This valve seat grinding tool 21 is constructed by inserting a revolution shaft 22 into the valve guide 3, sandwiching the valve guide 3 from both ends with conical chucks 23a and 23b provided at both ends of the revolution shaft 22, and inserting the revolution shaft 22 into the revolution shaft 22. is fixed to the valve guide 3, and the grindstone 24 is rotated around the rotation axis 23 while revolving around the revolution axis 22, and sent in the direction of the valve axis shown by the arrow X by the protrusion and retraction of the rotation axis 23. The structure is such that the valve seat is ground sequentially.

<Problems to be Solved by the Invention> However, in the conventional valve seat grinding tool 21, the upper and lower end portions 3a and 3b of the valve guide 3 that the conical chuck portions 23a and 23b come into contact with are generally uneven due to long-term use of the internal combustion engine. Since this is the part where the wear is most severe, it is not possible to accurately position and fix the revolution shaft 22 to the valve shaft center line CL, and the revolution shaft 22 becomes loose, causing the valve seat 2 to become incompatible with the valve shaft CL. The disadvantage is that it cannot be precisely ground concentrically.
Further, since it is necessary to approach and connect the conical chuck portion 23b to the tip of the revolution shaft 22 inserted through the valve guide 3 from the side opposite to the valve seat 2, setting the revolution shaft 22 takes time. In addition, since the grindstone 24 is configured to rotate, revolve, and feed in the axial direction, it is time-consuming to set the revolution axis, rotation axis, and feed direction of the grindstone before grinding. The drawback is that the grinding process itself takes time because it cannot be ground all at once. Moreover, the revolution and rotation mechanism 25 of the grindstone 24 is quite heavy, and this
Since the valve guide 3 is supported by the valve guide 3 via the valve guide 2, an eccentric load is applied to the valve guide 3 as it revolves, and this may cause the inner surface of the valve guide 3 to wear out.
Additionally, the complex structure shown makes the device expensive.

Therefore, an object of the present invention is to fix the centering rod, which is the center of rotation of the grinding wheel, to the central part of the valve guide, which has less wear, without requiring any effort, so that the center line of the grinding can be accurately aligned with the valve shaft, and to To provide a valve seat grinding tool capable of quickly and accurately grinding a valve seat with a simple and inexpensive configuration by rotating the tool around a centering rod and contacting the entire surface of the valve seat. be.

<Means for Solving the Problems> In order to achieve the above object, the valve seat grinding tool for an internal combustion engine of the present invention is inserted into a valve guide, and has an inner periphery having a tapered surface that widens toward the lower end. an outer cylinder having a surface and a plurality of axially extending closed slits, the outer cylinder being fitted onto the outer cylinder so as to be movable in the axial direction, being fixed to the outer cylinder with a screw, and abutting against the upper end of the valve guide; a stopper that positions the lower part of the outer cylinder at the center of the valve guide when the outer cylinder contacts the valve guide; and a stopper that is inserted into the outer cylinder so as to be movable in the axial direction, and has a tapered inner circumferential surface of the outer cylinder expanded in diameter at its lower end. a centering rod consisting of an actuating rod having a tapered portion corresponding to the tapered surface of the centering rod; and a connecting portion rotatably fitted onto the upper part of the outer cylinder of the centering rod and detachable from the drive shaft. A ring-shaped member at the upper end and a disc-shaped grindstone attached concentrically to the ring-shaped member to grind the valve seat are provided, and the operating rod of the centering rod is moved in the axial direction to operate the lower part of the outer cylinder. It is characterized in that the centering rod is fixed to the valve guide by expanding at the tapered part of the rod and pressing the lower part of the outer cylinder against the center part of the valve guide.

<Function> First, position the stopper so that when the stopper fitted onto the outer cylinder contacts the upper end of the valve guide, the center of the closing slit of the outer cylinder is positioned at the axial center of the valve guide. Fix it to the outer cylinder with screws. Next, after inserting the centering rod into the valve guide so that the stopper contacts the upper end of the valve guide, move the actuating rod in the opposite axial direction of the valve guide, and use the tapered part at the lower end to align the centering rod with the tapered surface of the outer cylinder. The inner circumferential surface having the inner circumferential surface is pressed to expand in the radial direction. This results in
The portion of the outer cylinder having a plurality of closing slits is largely enlarged in diameter and tightly contacts the central portion of the valve guide where wear is low, and the centering rods are fixed to the valve guide with their center lines aligned with each other. Next, a ring-shaped member with a disk-shaped grindstone attached concentrically to the centering rod is rotatably fitted onto the centering rod, and a drive shaft is connected to the connecting portion at the upper end of this ring-shaped member to rotate the disk-shaped grindstone. ,
Grind the valve guide.

<Examples> Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

In FIG. 1, 1 is a cylinder cover of an internal combustion engine, 2 is a valve seat provided on the cylinder cover 1, and 3 is a cylinder cover of an internal combustion engine.
A valve stem (not shown) is fitted, and the cylinder cover 1
4 is a valve seat grinding tool for grinding the valve seat 2, and 5 is an air motor for driving the valve seat grinding tool 4.

The valve seat grinding tool 4 includes a centering rod 6 inserted into the valve guide 3, an annular member 10 rotatably fitted onto the upper part of the centering rod 6, and an annular member 10.
It consists of a disk-shaped grindstone 11 that is attached concentrically to the valve seat 2 and grinds the valve seat 2. The centering rod 6 has an outer cylinder 8
and is fitted onto this outer cylinder 8 so as to be movable in the axial direction,
A stopper 9 is fixed to this outer cylinder 8 with a screw.
and an actuating rod 7 inserted into the outer cylinder 8 so as to be movable in the axial direction. The outer cylinder 8 is formed with an inner circumferential surface 8b having a tapered surface that widens toward the lower end, and three closed slits 8a extending in the axial direction with closed slits 8a arranged at equal intervals with a phase of 120°. While this is provided, a large diameter hole 8c is formed in the upper end surface. On the other hand, the actuation rod 7 that fits into the outer cylinder 8 has an inner peripheral surface 8b having a tapered surface of the outer cylinder 8 at the lower end.
While fixing the tapered part 7a that expands the diameter of the outer cylinder 8, a threaded part 7b is provided at the upper end, and this threaded part 7b is attached to a hexagonal head that engages with the large diameter hole 8c at the upper end of the outer cylinder 8, as shown in FIG. The hexagonal head 7 is screwed into the female screw of the part 7c.
The actuating rod 7 can be moved up and down into the outer cylinder 8 by rotation c. Therefore, by raising and lowering the actuating rod 7, a tapered portion 7a is formed on the inner circumferential surface 8b having a tapered surface.
The lower part of the outer cylinder 8 can be expanded and contracted by moving them toward and away from each other. In addition, the ring-shaped stopper 9 that fits onto the outer cylinder 8 can be attached to the outer cylinder 8 with an attached fixing screw 9a.
When the outer cylinder 8 is inserted into the valve guide 3, it comes into contact with the upper end of the valve guide 3, and the central part of the closing slit 8a at the bottom of the outer cylinder 8 is inserted in the axial direction of the valve guide 3. It is now positioned in the center.

On the other hand, the ring-shaped member 10 has roller bearings 10b, 10b, 10b mounted on the inner periphery of the cylinder 10a via spacers 10c, 10c, 10c,
A tightening ring 10e is screwed onto the upper end of the cylinder 10a via an upper lid 10d, and the roller bearing 1
The centering rod 6 is tightly fitted to the outer cylinder 8 of the centering rod 6 via the centering rod 0b in a removable manner. The tightening ring 10e has spline shafts 12a (fifth and sixth
Spline hole 1 into which the spline (see figure) is removably inserted
0f is provided as shown in FIGS. Note that the upper lid 10d serves as a stopper for the spline shaft 12a.

A small diameter portion 10g having a male thread on the outer periphery is formed at the lower end of the cylinder 10a of the annular member 10, and a boss 11a of the disc-shaped grindstone 11 is screwed onto this small diameter portion 10g, and is integrally baked into the boss 11a. Inclination θ of the conical surface 11c of the fixed disc-shaped grindstone 11b
is the angle specific to the valve seat 2 to be ground (e.g.
45° or 30°).

Using the valve seat grinding tool configured as described above, the valve seat 2 is ground as follows.

First, before the centering rod 6 is inserted into the valve guide 3, when the stopper 9 comes into contact with the upper end of the valve guide 3, the center part of the closing slit 8a of the outer cylinder 8 is located at the axial center of the valve guide 3. The stopper 9 is positioned so that the stopper 9 is positioned at the outer cylinder 8, and the stopper 9 is fixed to the outer cylinder 8 using the attached fixing screw 9a. Subsequently, the centering rod 6 is inserted into the valve guide 3 so that the stopper 9 contacts the upper end of the valve guide 3, and then the hexagonal head 7c is turned to tighten the actuating rod 7 in the upward direction shown by the arrow X. Then, the tapered portion 7a at the lower end of the actuating rod 7 presses the tapered inner circumferential surface 8b of the outer cylinder 8 with which it comes into contact, and expands the outer cylinder 8 in the radial direction indicated by the arrow Y in a plane perpendicular to the axis. let The force required for this expansion is relatively small because there are three closed slits 8a at the lower part of the outer cylinder 8, that is, at the location where the tapered inner peripheral surface 8b is located, and because the slits 8a are located at equal intervals, the force required for this expansion is relatively small. , the outer cylinder 8 expands evenly.
Furthermore, since the closed slit 8a is not an open slit that reaches the lower end of the outer cylinder 8, the outer cylinder portion corresponding to the center of the closed slit 8a mainly expands largely, and the lower end of the outer cylinder hardly expands. Therefore, the outer cylindrical part, which expands greatly, is fixed to the central part of the valve guide 3, which is less abraded, so that the seventh part, which fixes the revolution shaft 22 at the upper and lower ends of the valve guide 3, which is considerably abraded, is fixed.
Unlike the conventional example shown in the figure, the center line of the centering rod 6 can be precisely aligned with the valve stem. In addition, the outer cylinder 8
Since the lower end of the centering rod 6 does not expand, the centering rod 6 can be easily inserted into the valve guide 3. Furthermore, instead of connecting the conical chuck portion 23b to the revolution shaft 22 from the opposite side of the valve seat 2 as in the conventional example shown in FIG. 7, centering can be performed quickly by simply turning the hexagonal head 7c from the valve seat 2 side. can.

Next, the ring-shaped member 10 is externally fitted onto the centering rod 6 from above. Then, connect the spline shaft 12a of the adapter 12 attached to the air motor 5 to the spline hole 1 of the tightening ring 10e of the annular member 10.
0f and rotate the annular member 10. Since the air motor 5 and the annular member 10 are connected by a spline connection, they can be easily attached and detached. During grinding, the air motor 5 is held by hand or the like so that the weight of the air motor 5 does not apply to the valve seat 2 via the disc-shaped grindstone 11. The spline connection not only has the advantage of being detachable as described above, but also allows movement in the axial direction, so if the air motor 5 is held slightly floating, only the ring-shaped member 10, which is relatively light due to its simple structure, can be used. It has the advantage that it descends under its own weight as the grinding progresses, and no undue force is applied to the valve seat.

Due to the rotation of the ring-shaped member 10, the disc-shaped grindstone 11
rotates around the accurately centered centering rod 6 while descending under its own weight, and moves the valve seat 2 accurately and all at once on the conical surface 11c with an angle θ equal to the angle specific to the valve seat 2. Grind. Such an operation cannot be achieved in the conventional example in which the valve seat 2 is ground while revolving around the revolution axis 22 and rotating around the rotation axis 23 and moving in the axial direction X, as shown in FIG. It is clear that the example allows the valve seat 2 to be ground more quickly than the conventional example. Since the disc-shaped grindstone 11 simply rotates around the centering rod 6, an eccentric load is not applied to the valve guide 3 as in the conventional example, and therefore the inner surface of the valve guide 3 is not worn. Further, the ring-shaped stopper 9 seals the upper end of the valve guide 3, prevents grinding stone powder from entering the valve guide 3, and prevents wear of the valve guide 3 due to the grindstone powder.
This valve seat grinding tool 4 can grind various valve seats by changing the stopper position and the diameter of the centering rod and disk-shaped grindstone. Moreover, it has a simple structure and is lightweight, so it is easy to operate, and unlike the conventional example. It does not take much time to set up the grinder, and because it grinds all at once using only rotation, it can grind quickly.

<Effects of the Invention> As is clear from the above description, the valve seat grinding tool for an internal combustion engine of the present invention includes an inner peripheral surface having a tapered surface that widens toward the bottom and an outer cylinder having a plurality of axial closing slits; Fitted onto this outer cylinder so as to be movable in the axial direction,
A centering rod is composed of a stopper fixed with a screw, and an actuation rod that is movably inserted in the axial direction into the outer cylinder and has a tapered part that expands the diameter of the inner circumferential surface having the tapered surface at the lower end. When the outer cylinder is inserted into the valve guide, the stopper that contacts the upper end of the valve guide positions the lower part of the outer cylinder in the center of the valve guide where there is less wear, and the tapered part of the actuating rod moves in the axial direction. Expand the lower part of the outer cylinder to fix it to the central part of the valve guide, and attach a disc-shaped grindstone concentrically to the upper part of the outer cylinder of the above-mentioned centering rod, which is centered exactly in line with the valve shaft, and Since a ring-shaped member with a removable connecting part to the drive shaft is rotatably fitted on the upper end, the valve guide is subject to a lot of wear and tear.
Compared to the conventional method, which requires labor-intensive centering at the lower end, accurate centering is easier and more accurate grinding is possible, and grinding is performed by the revolution, rotation, and axial movement of the grindstone. Compared to conventional examples with complicated configurations, rapid grinding can be performed using only the rotation of the disc-shaped grindstone, even with an inexpensive configuration.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of an embodiment of the present invention, Fig. 2 is a detailed partial sectional view of the upper part of the centering rod, Fig. 3 is a partial sectional view of the tightening ring, and Fig. 4 is a partial sectional view of the tightening ring. 5 is a side view of the spline shaft, FIG. 6 is a plan view of the spline shaft, and FIG. 7 is a front view of a conventional valve seat grinding tool. 2... Valve seat, 3... Valve guide, 4... Valve seat grinding tool, 6... Centering rod, 7... Operating rod, 7a
... Tapered part, 8 ... Outer cylinder, 8a ... Closed slit, 8b ... Inner peripheral surface having a tapered surface, 9 ... Stopper, 10 ... Ring-shaped member, 10f ... Spline hole, 11 ... Disk shape Whetstone, 12...adapter,
12a...Spline shaft.

Claims (1)

[Claims] 1. An outer cylinder that is inserted into a valve guide and has an inner circumferential surface having a tapered surface that becomes wider toward the lower end and a plurality of closed slits that extend in the axial direction; a stopper that is fitted onto the outer cylinder so as to be movable in the axial direction, is fixed to the outer cylinder with a screw, and positions the lower part of the outer cylinder at the center of the valve guide when it comes into contact with the upper end of the valve guide; a centering rod that is inserted into the outer cylinder so as to be movable in the axial direction and has at its lower end a tapered portion corresponding to the tapered surface capable of expanding the diameter of the inner circumferential surface having the tapered surface of the outer cylinder; , a ring-shaped member that is rotatably fitted onto the upper part of the outer cylinder of the centering rod and has a connection part at the upper end that is detachable from the drive shaft; and a ring-shaped member that is attached concentrically to the ring-shaped member and grinds the valve seat. A disc-shaped grindstone is provided, the operating rod of the centering rod is moved in the axial direction, the lower part of the outer cylinder is expanded by the tapered part of the operating rod, and the lower part of the outer cylinder is placed in the center of the valve guide. A valve seat grinding tool for an internal combustion engine, characterized in that the centering rod is fixed to the valve guide by pressing.