JPS633366Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a hydraulic lifter for a direct-drive valve in an overhead cam engine.

(Prior Art) Adjusting the gap between the valve lifter and cam of a direct-drive overhead cam engine, that is, adjusting the tappet, is extremely difficult and wastes a lot of time and effort. Moreover, since the gap could not be reduced to zero, there was a drawback that the engine generated a lot of noise during operation.

In order to solve this drawback, various hydraulic valve lifters have been devised in the past in which the valve lifter is brought into contact with the cam using hydraulic pressure, and the present applicant also disclosed this in Japanese Patent Application No. 1984-8415. The technology has improved.

As shown in FIG. a box-like second plunger element 6 which is receivably received and has an internal chamber 5 formed therein; A chamber 8 is formed, a hole 9 is formed in the lower end wall 7 to communicate the inner chamber 5 and the cylinder chamber 8, and a check valve 10 is incorporated in the hole 9. A compression coil spring 11 is disposed in the cylinder chamber 8 and acts in a direction to push out the second plunger element 6 from the first plunger element 3. 6 has communicating holes 12 and 13 in its side wall that are always in communication with each other, and the communicating hole 12 of the first plunger element 3 is always in communication with an oil passage 14 formed in the cylinder head 1 and opening into the plunger bore 2. There is. Further, the upper end wall 15 of the second plunger 6 is connected to the valve lift cam 1.
In direct contact with 6.

With this configuration, when a gap occurs between the second plunger element 6 and the valve lift cam 16, the second plunger element 6 is pushed out from the first plunger element 3 by the compression coil spring 11, and the gap is filled. Supplement. At this time, oil flows from the inner chamber 5 into the cylinder chamber 8 via the check valve 10.

(Problems to be Solved by the Invention) However, the conventional hydraulic valve lifter described above has the following problems.

First, since oil is supplied from the inner chamber 5 of the second plunger element 6 to the cylinder chamber 8, and both the inner chamber 5 and the cylinder chamber 8 are filled with oil, the weight of the valve lifter itself becomes heavy. There were problems in that the inertial mass increased, resulting in poor power performance and fuel efficiency, as well as poor response. Further, since the structure is complicated, manufacturing costs are high, and maintainability and durability are also poor.

The present invention was devised in view of the above problems, and its purpose is to provide a hydraulic lifter that is lightweight and has a simple structure.

(Means for Solving the Problems) As a means for solving the above problems, the present invention has an inner lifter made of a hollow cylindrical body whose upper surface is brought into contact with a cam, and a partition wall that partitions the inside into upper and lower parts. an outer lifter that is made of a cylindrical body and connects a valve stem to the lower surface of the partition wall, the outer circumferential surface of the outer lifter is brought into sliding contact with the lifter hole of the head main body, and the outer circumferential surface of the inner lifter is placed on the upper side of the outer lifter. A high-pressure oil chamber is formed between the inner lifter and the upper surface of the partition wall of the outer lifter by sliding contact with the inner peripheral surface, and hydraulic pressure is supplied to the high-pressure oil chamber from the oil main hole of the head main body via a check valve. The inner lifter is supplied so that the upper surface of the inner lifter is always brought into contact with the cam.

(Function) With the above configuration, hydraulic pressure is supplied to the high pressure oil chamber via the check valve so that there is no gap between the inner lifter and the cam, and when the inner lifter is pushed down by the cam, the pressure is supplied to the high pressure oil chamber. A check valve prevents the oil from flowing back into the oil main hole, maintaining oil pressure in the high-pressure oil chamber.

And the inner lifter is hollow,
Since oil is only filled in the high-pressure oil chamber formed between the outer lifter and inner lifter, the weight of the lifter can be reduced, and the thickness of the inner lifter can be made thinner in the vertical direction. This contributes to reducing the weight of the lifter, and the inertial mass of the lifter can be reduced.

In addition, since it is composed of only an inner lifter and an outer lifter, the structure is extremely simple and maintainability and durability can be improved.

(Example) Next, an example of the present invention will be described based on FIG.

Reference numeral 17 denotes a head body, which has a valve 19 for opening and closing the manifold 18, and this valve 19 is connected to the cam 2.
Driven by 0. A lifter 21 is installed between the valve 19 and the cam 20, which is the main part of the present invention to reduce the clearance to zero.

This lifter 21 includes an inner lifter 22 made of a hollow cylindrical body whose upper surface is in contact with the cam 20;
It consists of an outer lifter 24 made of a cylindrical body having a partition wall 23 that partitions the inside into an upper and lower part. is connected. Further, the outer circumferential surface of the inner lifter 22 is brought into sliding contact with the upper inner circumferential surface of the outer lifter 24. And inner lifter 2
2 and the upper surface of the partition wall 23 of the outer lifter 24 becomes a high pressure oil chamber 27.
By supplying hydraulic pressure to the inner lifter 22
is moved in the direction in which it is pushed out by the outer lifter 24.

Hydraulic pressure is supplied to the high-pressure oil chamber 27 through an oil main hole 28 provided in the head body 17, through a check ball 30 of a check valve 29, and through a supply port 31 of an outer lifter 24.

Therefore, in the above-mentioned hydraulic lifter of the direct drive valve, when the engine (not shown) is rotating, the check ball 30 of the check valve 29 is moved by the oil pressure of the oil main hole 28 when the cam 20 is in the base circle. Pushed to the left, the oil enters the high-pressure oil chamber 27, reducing the gap between the cam 20 and the inner lifter 22 to zero. When the cam 20 rotates, the inner lifter 22 is pushed down and the oil pressure in the high pressure oil chamber 27 increases, causing the check ball 3
0 to the right to prevent backflow of oil, the oil pressure in the high pressure oil chamber 27 is maintained and the valve 19
is activated. Note that even after the engine is stopped, there is little oil leakage because the high-pressure oil chamber 27 is located at the inner bottom of the cup-shaped outer lifter 24.

In addition, in this embodiment, the inner lifter 22 is a hollow sealed body and has a thinner vertical thickness.
It is possible to use a structure with extremely high rigidity and reduce the wall thickness, making it possible to further reduce the weight.

(Effects of the Invention) As described in detail above, the invention is a hydraulic lifter composed of an inner lifter made of a hollow cylindrical body with a cam in contact with its upper surface, and an outer lifter made of a tubular body with a partition wall that divides the interior into upper and lower sections, which simplifies the structure and improves maintainability and durability.

In addition, since only the high-pressure oil chamber between the inner lifter and outer lifter is filled with oil, the weight does not increase.Furthermore, the inner lifter is thinner and lighter, reducing the inertial weight of the lifter. can do. Therefore, the response of the engine is improved, and the power performance and fuel efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part showing an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a main part showing an example of a conventional hydraulic lifter. 17...Head body, 19...Valve, 20...
... cam, 22 ... inner lifter, 23 ... bulkhead, 24 ... outer lifter, 25 ... lifter hole, 27 ... high pressure oil chamber, 28 ... oil main hole, 29 ... check valve.

Claims (1)

[Scope of utility model registration request] an inner lifter made of a hollow cylindrical body having an upper surface in contact with a cam, and an outer lifter made of a cylindrical body having a partition wall that partitions the inside into upper and lower parts and connecting a valve stem to the lower surface of the partition wall, the outer periphery of the outer lifter A high-pressure oil chamber is formed between the inner lifter and the upper surface of the partition wall of the outer lifter by bringing the surface into sliding contact with the lifter hole of the head main body, and by bringing the outer peripheral surface of the inner lifter into sliding contact with the upper inner peripheral surface of the outer lifter. and supplying hydraulic pressure to the high pressure oil chamber from the oil main hole of the head main body via a check valve so that the upper surface of the inner lifter is always in contact with the cam. Hydraulic lifter for driven valves.