JPH0437202Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a direct valve lifter for an internal combustion engine.

[Prior Art] Conventionally, the structure of the vicinity of a valve lifter provided directly above the intake and exhaust valves of an internal combustion engine is as shown in FIG.

That is, the upper ends of the intake and exhaust valves 1, which are urged upward by the valve springs 2, slide into contact with the valve lifter 3, and the valve lifter 3 has its upper surface slidably contacted by the cam 4 via the shim 5. Driven. The valve lifter 3 slides on the inner peripheral surface of a bore 7 provided in the cylinder head 6 and is driven in the vertical direction, and can also rotate in the circumferential direction.

Conventionally, direct type valve lifters have often been made of chromium, molybdenum steel, etc., which have good heat resistance and wear resistance, but steel valve lifters have had the following problems.

[Problem that the invention aims to solve] In other words, since both the cam and the lifter of a steel valve lifter are made of steel, even if the tappet clearance is adjusted with shims, etc., there will be no striking sound between the metals. , it is one of the engine noises. In order to suppress this noise below a certain value, the tappet clearance cannot be made large enough, and the engine output value is not optimal.

Also, since it is made of steel, there are limits to how much it can be reduced in weight, and there are limits to how much inertial mass can be reduced.

Furthermore, the shims and lifters are usually made of chrome-molybdenum steel, which is a difficult-to-cut material and requires high accuracy, which requires a large number of man-hours to process.

In addition, surface treatments such as phosphoric acid coatings have become necessary to ensure lubricity and conformability of cams and lifters.

The present invention can alleviate the above-mentioned problems. In other words, it significantly reduces the tappet sound between the cam and valve lifter, reduces engine noise, improves engine output through the reduction of inertial mass, and reduces machining and assembly man-hours. The purpose is to provide a valve lifter that can significantly reduce the

[Means for solving the problem] The valve lifter of the present invention that meets this purpose is a direct-type valve lifter provided directly above the valve, in which the valve lifter is made of resin, and
A direct-on type resin valve lifter in which the outer periphery of a cross section perpendicular to the axis of the lifter skirt is alternately provided with parts having a larger diameter than the inner diameter of the bore in which the valve lifter slides and parts having a smaller diameter than the bore inner diameter. Consists of.

[Function] In the valve lifter with the above configuration, the lifter and shim are integrally made of resin, so the cam and the top surface of the valve lifter come into metal-to-resin contact, which reduces the striking noise considerably compared to metal-to-metal contact. and engine noise is also reduced. Therefore, the tappet clearance is not restricted from the standpoint of reducing noise, and by providing an appropriate tappet clearance, the engine output can be improved.

Furthermore, since the valve is made of resin instead of steel, the weight is reduced, and the inertial mass of the valve lifter, which moves up and down in accordance with the rotation of the cam, is reduced, improving engine output.

Furthermore, since the outer circumferential shape of the lifter skirt part has a different size, when the valve lifter is inserted into the bore, the large diameter part presses against the bore inner diameter due to the elastic deformation of the lifter skirt part, and the escape of deformation is absorbed by the small diameter part. It is automatically deformed and comes into sliding contact with the inner circumferential surface of the bore. Moreover, this automatic deformation automatically accommodates the difference in thermal expansion between the bore and the bore during use. Therefore, there is no need for special machining on the outer periphery of the valve lifter, and it can be used as an integrally molded product, reducing the number of machining steps.

[Embodiments] Hereinafter, preferred embodiments of the direct type resin valve lifter according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 and 2 show a first embodiment of the present invention. The valve lifter 11 is used for the intake of an internal combustion engine.
This is a direct valve lifter that is installed directly above the exhaust valve, and its top surface is placed in direct sliding contact with the cam without using any shims. The valve lifter 11 is made of resin.

The resin that makes up the valve lifter 11 has an operating temperature of approx.
It can withstand 200℃ and is made of PEEK (polyether).
etherketone), PAI (polyamideimide), PI
(polyimide), PPS (polyphenylene sulfide), phenol, etc. are used. Teflon or carbon may be mixed into the resin in order to improve sliding properties and wear resistance. In addition, carbon and glass are added to the resin to adjust the thermal expansion coefficient to match that of the aluminum alloy that is the constituent material of the cylinder head.

The valve lifter 11 has a substantially flat top portion 12 and a cylindrical lifter skirt portion 13 extending downward from the outer periphery of the top portion 12 .

The diameter of the top portion 12 is smaller than the inner diameter of the bore of the cylinder head into which the valve lifter 11 is slidably inserted, and the diameter is smaller than the outer diameter of the lifter skirt portion 13. This is because the plate-shaped part is solid, so if there is a thermal expansion difference between it and the bore in the radial direction, it is difficult to escape that thermal expansion difference by deforming the lifter. By forming it into a small diameter. A protrusion 14 that protrudes downward is formed in the center on the surface of the top portion 12 opposite to the surface that comes into sliding contact with the cam.
The upper end of the valve stem rotatably comes into sliding contact with the lower surface of the valve stem, and receives the upward biasing force from the valve spring through the valve stem.

The lifter skirt portion 13 is a hollow cylindrical body having a substantially uniform wall thickness, and its outer periphery has a shape in which large diameter portions 15 larger than the bore inner diameter and small diameter portions 16 smaller than the bore inner diameter are alternately provided. It is formed. This is achieved in the first embodiment by forming the lifter skirt portion 13 into a polygonal rice ball shape with smoothly curved corners.

Next, the operation in the first embodiment will be explained.

First, since the valve lifter 11 is made of resin,
The cam is a contact between metal and resin, and regardless of the existence of tappet clearance, the hitting sound will be reduced.
Engine noise is reduced. Furthermore, since resin weighs less than metal, the inertial mass of the valve lifter 11 is significantly reduced, thereby improving engine output.

This is the material that constitutes the valve lifter 11.
PEEK, PAI, PI, PPS, and phenol are all
Since it can withstand regular use at 200℃, there will be no problems with heat resistance even if it is used around the bore, where the temperature is normally below 200℃. In addition, the difference in thermal expansion can be adjusted by adjusting the amount of carbon and glass mixed in the resin.
By matching the coefficient of thermal expansion of 1 to that of the aluminum alloy material of the cylinder head, it is possible to keep the coefficient of thermal expansion to a minimum. In addition, the outer circumferential shape of the lifter skirt portion 13 has a shape in which portions that are equal to or larger than the bore inner diameter and portions that are smaller than the bore inner diameter are alternately provided in the circumferential direction, so that the thermal expansion of the large portion is elastic. The deformation allows the lifter skirt portion 13 to escape into a small portion, and does not cause the lifter skirt portion 13 to lock into the bore due to an excessive tight fit during use. Moreover, the lifter skirt part 13 always fits in the bore due to the elastic deformation of the lifter skirt part 13, and the slidability is also maintained satisfactorily by the appropriate pressing force. Such fitability is obtained because the resin is elastically deformable, and the lifter skirt portion 1
Even if there is a slight dimensional deviation in the outer circumferential shape of 3, it will be automatically absorbed and achieved through deformation. Therefore, the outer periphery of the lifter skirt portion 13 does not need to be machined with high precision, and the necessary dimensions can be obtained at one time by injection molding. Therefore, compared to conventional steel lifters that require machining, the number of machining steps is significantly reduced.

The fitability utilizing elastic deformation as described above can be obtained because the lifter skirt portion 13 is a cylindrical body, and is difficult to achieve with a plate-like body that is solid in the radial direction like the top portion 12. Therefore, even if a thermal expansion difference occurs, the top 12 is made smaller than the bore inner diameter.
It is designed so that it does not interfere with the bore.

Second Embodiment FIGS. 3 and 4 show a second embodiment of the present invention. In the second embodiment, parts that are similar to those in the first embodiment are given the same reference numerals as those in the first embodiment, and their explanation will be omitted, and different parts will be explained.

In the second embodiment, the valve lifter 11 is
It is made of a material such as PEEK, PAI, PI, PPS, phenol, etc., mixed with carbon, glass, etc. to have almost the same thermal expansion as the cylinder head. The valve lifter 11 consists of a plate-shaped top part 12 and a cylindrical lifter skirt part 13, and a plurality of large diameter parts 17 are provided on the outer periphery in the circumferential direction. The large diameter portion 17 is equal to or larger than the inner diameter of the bore into which the valve lifter 11 is inserted, and extends in the vertical direction. The outer circumferential shape of the valve lifter other than the large diameter portion 17 has a smaller diameter than the bore inner diameter. The large diameter portion 17 is formed by injection molding so as to protrude outward from the inner diameter of the bore, as shown by the two-dot chain line in FIGS. 3 and 4, and is worked into the shape shown by the solid line using a pot broach or the like. Because it is resin-processed, it can be easily processed, making processing much easier than conventional machining of difficult-to-process steel materials.

Also in the valve lifter 11 of the second embodiment, weight reduction, noise reduction, improvement in fitability into the bore, and ease of machining have been achieved.

[Effect of the invention] Therefore, when using the direct type resin valve lifter of the invention, since the valve lifter is made of resin,
It is possible to reduce weight and engine noise. In addition, the outer diameter of the valve lid is alternately provided with large diameter parts larger than the bore inner diameter and parts smaller than the bore inner diameter, which improves the degree of freedom in deforming the valve lifter outer diameter and improves the ability to follow the bore inner diameter. It is possible to improve the performance of the valve lifter and to facilitate valve lifter machining.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a direct-top type resin valve lifter according to a first embodiment of the present invention, Fig. 2 is a bottom view of the valve lifter of Fig. 1, and Fig. 3 is a direct-top type resin valve lifter according to a second embodiment of the present invention. FIG. 4 is a bottom view of the valve lifter shown in FIG. 3, and FIG. 5 is a sectional view of the engine near the conventional valve lifter. 11... Valve lifter, 12... Top, 13...
...Lifter skirt part, 14...Protrusion part, 15,1
7...Large diameter section, 16...Small diameter section.

Claims (1)

[Scope of utility model registration request] In the direct type valve lifter provided directly above the valve, the valve lifter is made of resin, and the outer circumferential shape of the cross section perpendicular to the axis of the lifter skirt portion is a portion having a larger diameter than the inner diameter of the bore with which the valve lifter slides. A direct type resin valve lifter characterized by having a shape in which portions having a diameter smaller than the bore inner diameter are alternately provided.