JPH0814013A - Valve mechanism for multivalve engine - Google Patents

Abstract

PURPOSE:To provide a valve mechanism having simple constitution capable of effectively restraining the abrasion of the abutting part of a crosshead for interlocking plural valves. CONSTITUTION:A recessed part 11e is provided on the lower surface of the arm 11a of a crosshead 11. The top of a stem 12a is inserted into the recessed part 11e from a lower side to make the end surface of the stem 12a abut on the bottom surface of the recessed part 11e. By setting the inner diameter D of the recessed part 11e to 110-120% of the outer diameter (d) of the stem 12a and also nearing the lower end of an annular gap 13, formed of the inner peripheral surface of the recessed part 11e and the outer peripheral surface of the stem 12a, to the upper surface of a valve spring retainer 14a; oil, dropped on the upper surface of the valve spring retainer 14a from the crosshead 11, is sucked to be supplied to the abutting part of the stem 12a and the crosshead 11 by utilizing the gap 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve mechanism of a multi-valve engine having a plurality of intake / exhaust valves per cylinder, and more specifically, abutting of a plurality of valves and a crosshead for interlocking the valves. The present invention relates to a valve mechanism having a simple structure suitable for suppressing wear of parts.

[0002]

2. Description of the Related Art In a conventional valve mechanism of a multi-valve engine, a guide 2 is erected on the upper surface of a cylinder head 1 as shown in FIG. Was attached to. Further, one arm 3a of the crosshead 3 is brought into contact with the top surface of the stem 4a of one valve from above, and the adjusting screw 3d attached to the other arm 3b.
The lower end of the valve is brought into contact with the top surface of the stem 4b of the other valve from above so that the rocker arm 5 pushes down the stems 4a and 4b of both valves via the crosshead 3.

Then, a recess 3e for receiving the top of the stem 4a of the valve is provided on the lower surface of the arm 3a of the crosshead 3, and an oil passage 3f reaching the bottom surface of the recess 3e is provided on the arm 3a. The oil jetted and supplied from the provided oil passage 6a to the surface of the crosshead 3 through the oil passage 5a provided in the rocker arm 5 is guided from the oil passage 3f to the bottom surface of the recess 3e to contact the crosshead 3 and the valve 4a. Was lubricated (see, for example, FIG. 3 of Japanese Utility Model Laid-Open No. 3-119509). 3g is an oil passage for guiding oil to a sliding portion (guide hole 3h provided in the leg portion 3a) with the guide 2, 7a and 7b are valve springs, 8a and 8b are valve spring retainers, and 9 is a push rod, Oil discharged from an oil pump (not shown) is supplied to an oil passage 6a provided on the rocker shaft 6.

However, even if a large amount of oil is supplied, it is impossible to completely prevent abrasion of the top surface of the stem 4a, and the top surface of the stem 4a leaves the opening of the oil passage 3f. Worn as an attachment. Therefore, when the protrusion formed on the top surface of the stem 4a is fitted into the oil passage 3f due to wear and has a blocking effect, or when a foreign substance flows into the oil passage 3f, the opening of the oil passage 3f is small. Since a sufficient amount of oil is not supplied, there is a possibility that wear of the top surface of the stem 4a will be accelerated.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple structure capable of effectively suppressing wear of a plurality of valves and an abutting portion of a crosshead for interlocking the valves. The challenge is to provide a valve mechanism.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to inserting the top of the stem from below into a recess provided in the lower surface of the arm of the crosshead, and contacting the end face with the bottom of the recess. In addition, the inner diameter of the recess is set to 110 to 120% of the outer diameter of the valve stem, and the lower end of the annular gap formed by the inner peripheral surface of the recess and the outer peripheral surface of the stem is set on the upper surface of the valve spring retainer. It is characterized by being close to each other.

[0007]

In the multi-valve valve mechanism configured as described above, the oil flowing on the surface of the crosshead drops from the arms of the crosshead and collects on the upper surface of the valve spring retainer. The oil dripping on the upper surface of the valve spring retainer is supplied to the contact portion between the top surface of the stem and the bottom surface of the recess due to the suction effect of the annular gap formed by the inner peripheral surface of the recess and the outer peripheral surface of the stem.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of an essential part showing an embodiment of a valve mechanism of a multi-valve engine according to the present invention, in which a leg portion 11c of a crosshead 11 can be raised and lowered by a guide 10 standing on the upper surface of a cylinder head (not shown). Is attached to. Also, one arm 1 of the crosshead 10
By contacting 1a with the top surface of the stem 12a of one valve from above, and contacting the lower end of the adjust screw 11d attached to the other arm 11b with the top surface of the stem 12b of the other valve from above, When the crosshead 11 is moved up and down along the guide 10 by a driving means such as a rocker arm or a cam (not shown), the stems 12a and 12b of both valves are simultaneously pushed down.

In this embodiment, the valve stem 12 is used.
A recess 11e for receiving the top of a is provided on the lower surface of the tip of the arm 11a of the crosshead 11. Further, the inner diameter D of the recess 11e is equal to the outer diameter d of the valve stem 12a, which is 11
After being set to 0 to 120%, the top of the stem 12a is inserted into the recess 11e from below, and the top surface is brought into contact with the bottom of the recess 11e so that the inner peripheral surface of the recess 11e and the outer peripheral surface of the stem 12a form an annular shape. The gap 13 is formed, and the lower end of the gap 13 faces the upper surface of the valve spring retainer 14a.

Reference numeral 11f is a guide hole provided in a leg portion 11c constituting a sliding portion with the guide 10, and 11g is a guide hole 11f.
An oil passage for guiding oil, 11h is a tip forming a contact surface with a rocker arm (not shown), 14b is a valve spring retainer of the other valve, and 15a and 15b are valve springs. Similarly, oil is injected and supplied.

In the valve mechanism of the multi-valve configured as described above, the oil supplied to the surface of the crosshead 11 is the arm 11a of the crosshead 11.
And then collects on the upper surface of the valve spring retainer 14a.

On the other hand, since the lower end of the annular gap 13 formed by the inner peripheral surface of the recess 11e and the outer peripheral surface of the stem 2a is brought close to the upper surface of the valve spring retainer 14a, the valve spring retainer is operated as described above. 14a
The oil accumulated on the upper surface of the above is supplied to the contact portion between the top surface of the stem 12a and the bottom surface of the recess 11e by the suction effect of the gap 13.

That is, the inner diameter D of the recess 11e is set to the stem 1
By setting the outer diameter d of 2a to 110 to 120%, the gap 13
While sufficiently increasing the effect of sucking up the oil by the oil, the circulation of the oil inside the gap 13 is ensured, and a necessary and sufficient amount of oil is supplied to the top surface of the stem 12a and the recess 11e.
Could be supplied to the abutting portion on the bottom surface of the. In the embodiment, the oil sump 16 is formed in the central portion of the upper surface of the valve spring retainer 14a so that the oil is easily accumulated on the upper surface of the retainer 14a, but the oil sump 16 is not always necessary.

When the inner diameter D of the recess 11e is smaller than 110% of the outer diameter d of the stem, the cross-sectional area of the passage formed by the gap 13 becomes too small and the amount of oil sucked up decreases. Since the width of the gap 13 becomes too narrow with respect to the surface tension of the oil and the circulation of the oil inside the gap 13 is impaired, new oil cannot be circulated and supplied. Furthermore, the recess 1
When the inner diameter D of 1e is set to be larger than 120% of the outer diameter d of the stem 12a, a gap 13 is generated against the surface tension of the oil.
Is too wide and the suction height of the oil is reduced, so that it is difficult to supply a sufficient amount of oil to the contact portion between the top surface of the stem 12a and the bottom surface of the recess 11e.

[0015]

As is apparent from the above description, according to the present invention, the valve spring retainer is mounted on the valve spring retainer by utilizing the annular gap formed by the inner peripheral surface of the recess provided in the arm of the crosshead and the outer peripheral surface of the stem. Since the oil collected in the valve is sucked up and supplied to the contact portion between the stem and crosshead, the structure of the valve mechanism is simplified and the entire top surface of the stem can be brought into contact with the bottom surface of the recess. In addition, since the oil supply amount does not decrease due to the inclusion of foreign matter, it is possible to suppress the wear of the contact portion between the valve stem and the crosshead.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of a valve mechanism of a multi-valve engine according to the present invention.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 10 Guide 11 Crosshead 11a, 11b Arm 11e Recess 12a, 12b Valve stem 13 Gap 14a, 14b Valve spring retainer 15a, 15b Valve spring 16 Oil sump D Inner diameter of recess 11e d Outer diameter of stem 12a

Claims (1)

[Claims] 1. A guide erected on an upper surface of a cylinder head of an engine, and one arm held up and down by the guide so as to abut against a top surface of a stem of one valve and the other arm of the other valve. A crosshead that comes into contact with the top surface of the stem and a drive unit that raises and lowers the crosshead are provided. The drive unit pushes down both valves via the crosshead, and the oil that flows on the surface of the crosshead is removed. A valve mechanism of a multi-valve engine in which a contact portion between a crosshead and a valve is guided to lubricate the contact portion, wherein a top portion of a stem is inserted from below into a recess provided in a lower surface of the arm. While making the end surface abut the bottom surface of the recess and setting the inner diameter of the recess to 110 to 120% of the outer diameter of the valve stem,
A valve mechanism for a multi-valve engine, characterized in that the lower end of an annular gap formed by the inner peripheral surface of the recess and the outer peripheral surface of the stem is brought close to the upper surface of the valve spring retainer.