JPS6242084Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic valve lifter having an inclined structure.

A hydraulic valve lifter is equipped with an outer cylinder and an inner cylinder fitted into the outer cylinder, with the outer cylinder abutting on a camshaft and the inner cylinder abutting a push rod leading to a rocker arm. A hydraulic chamber is formed between the outer cylinder and the inner cylinder, and an oil reservoir chamber is formed inside the inner cylinder. The oil pressure chamber communicates with the oil reservoir chamber through a check valve, and the oil reservoir chamber is connected to the oil supply hole drilled in the radial direction of the inner cylinder and the annular oil passage formed in the circumferential direction between the inner cylinder and the outer cylinder. connected to the source. The outer cylinder is displaced relative to the inner cylinder by the hydraulic pressure introduced into the hydraulic chamber from the oil reservoir chamber via the check valve, so that the tapepet clearance is always zero regardless of the thermal expansion of the cylinder.

Some of these valve lifters are not placed vertically but at an angle. In this case, if the engine is stopped with the oil supply hole in the inner cylinder facing downward, the atmospheric pressure applied from the push rod side will drain the oil in the oil reservoir chamber. exits while stopped. As a result, a sufficient amount of oil cannot be introduced from the oil reservoir chamber to the hydraulic chamber immediately after restarting, and the hydraulic pressure in the hydraulic chamber does not rise. As a result, there is no relative movement between the inner cylinder and the outer cylinder, resulting in inadequate tappet clearance, and the intake and exhaust valves connected to the rocker arm operate inappropriately, resulting in seating noise between the valve and the valve seat. , this continues until a sufficient amount of oil is introduced into the oil sump chamber from the oil pump.

In order to solve this problem, a check valve is also installed on the push rod side to prevent atmospheric pressure from acting on the oil sump chamber, and the structure is such that a sufficient amount of oil is ensured in the oil sump chamber and does not leak out while the engine is stopped. is proposed. However, such a double check valve structure unnecessarily complicates the structure of the valve lifter,
In addition, it may not function sufficiently for the following reasons.
First of all, the check ball is unable to perform its function of blocking atmospheric pressure sufficiently due to poor sealing due to poor machining of the seat surface of the check ball, and poor adhesion due to foreign matter such as oil sludge mixed into the oil. can be mentioned. Secondly, since the oil reservoir chamber is sealed by the check ball, air bubbles mixed in the oil remain in the oil reservoir chamber along with the oil, and the air bubbles are likely to be sucked into the oil reservoir chamber when the engine is restarted.

Therefore, an object of the present invention is to provide a valve lifter configuration that can ensure a sufficient amount of oil in the oil reservoir during stoppage with high reliability despite its simple structure.

The following will be explained with reference to the drawings. In FIG. 1, a lifter case 10 fixed to a cylinder block is shown.
The outer cylinder 12 is slidably inserted therein at an inclination angle of θ with respect to the vertical. The outer cylinder has one closed end surface 121 in contact with a cam 15 on the camshaft 14. From the other open end of the outer cylinder 12 to the inner cylinder 1
6 is slidably inserted, a push rod seat 18 is applied to its open end, and a ball portion 201 at one end of the push rod 20 is seated. The other end (not shown) of the push rod 20 is connected to a suction/discharge valve via a rocker arm.

A hydraulic chamber 24 is formed between the outer cylinder 12 and the inner cylinder 16, and a check ball (valve) 26 for opening and closing an oil supply hole 25 formed in the end face of the inner cylinder 16 is located.
The check ball 26 normally closes the oil supply hole 25 by a spring 30 that engages with a cap-shaped spring seat 28. Further, a spring 3 disposed within the hydraulic chamber 24
2 urges the inner cylinder 16 in a direction away from the camshaft 14, and also serves to press the spring seat 28 against the end face of the inner cylinder.

From the open end of the inner cylinder 16, a separator 36, which is formed by joining two members with a square cross section at their necks, is press-fitted until it abuts against the shoulder 164, and as a result, a first An oil reservoir chamber 38 and an annular second oil reservoir chamber 40 are formed. First oil sump chamber 38
communicates with the oil supply hole 25 and also communicates with the center hole 181 of the push rod 18 via the center hole 361 of the separator to supply oil to the rocker arm side. The annular second oil reservoir chamber 40 communicates with an annular oil passage 42 formed around it via an oil supply hole 39 formed in the radial direction of the inner cylinder 16, and this annular oil passage 42 communicates with the oil supply hole 123 of the outer cylinder, It communicates with an oil pump (not shown) via an oil supply path 43 and an oil path 103 in the lifter case 10 . The first oil reservoir chamber 38 and the second oil reservoir chamber 40 are electrically connected to each other through a communication hole 45 formed in the separator 36, and this communication hole 45 is connected to the oil supply hole 39 of the inner cylinder through a central hole 361. They are located at approximately diametrically opposite positions with the two sides in between.

Next, to explain the operation, when the engine is operating, the lubricating oil is pumped from the hydraulic pump (not shown) through the oil passage 10.
3, 123, enters the second oil reservoir chamber 40 through the oil supply hole 123 of the inner cylinder 16, the annular oil passage 42, and the oil supply hole 39 of the inner cylinder 16. The oil enters the first oil reservoir chamber 38 from the second oil reservoir chamber 40 through the communication hole 45 . Most of the oil in the first oil reservoir chamber 38 is used to lubricate the cylinder head valve mechanism through the separator center hole 361, the center hole 181 of the push rod seat 18, and the oil passage 202 in the push rod. The oil in the first oil reservoir chamber 38 also acts on the check ball 26 through the oil supply hole 25 on the end face of the inner cylinder, and opens the check ball 26 when the pressure in the hydraulic chamber 24 is lower than a set value. When the pressure in the hydraulic chamber 24 returns to the set value, the check ball 26 is closed. Thus, the pressure in the hydraulic chamber 24 is maintained at a set value so that the tapepet clearance is always zero during engine operation. Note that the oil in the hydraulic chamber 24 leaks to the oil supply side through a small gap between the outer cylinder 12 and the inner cylinder 16 to lubricate the sliding surfaces.

After the engine is stopped, the oil pump stops working, so the supply of oil to the second oil reservoir chamber 40 is stopped. Further, since atmospheric pressure acts through the central hole 181 of the push rod seat 18, the oil stored in the first oil reservoir chamber 38 returns to the oil supply system located at a lower location. In the present invention, the positional relationship between the oil supply hole 39 provided in the inner cylinder 16 and the communication hole 45 of the separator 36 is selected so that the two are positioned diametrically opposed to each other with the central hole 361 in between. Therefore, oil supply hole 3 when stopped
Regardless of the positional relationship between the center hole 361 and the communication hole 45, the amount of remaining oil at the level 1 determined where the horizontal line touches the lower surface of the center hole 361 can be ensured. Note that when the oil supply hole 39 and the communication hole 45 are horizontal as shown by the broken line, there is a drop slightly below l.

As described above, in the present invention, since a sufficient amount of oil remains in the first oil reservoir chamber 38 when the engine is stopped, inappropriate operation of the intake and exhaust valves and the accompanying seat seating at the time of restarting can be prevented. To explain this, assuming the most extreme case where the cam 14 has stopped on the lift curve as shown in Fig. 1, the reaction force of the valve spring installed on the intake valve or exhaust valve when the cam 14 is stopped is the push rod 20, As a result of pushing down the inner cylinder 16 via the push rod seat 18, the oil in the hydraulic chamber 24 flows out into the oil supply system through the fitting gap between the outer cylinder 12 and the inner cylinder 16. In other words, the position of the inner cylinder of the lifter is lower than the proper position due to oil leakage in the hydraulic chamber 24. When the cam 141 is restarted in this state and rotates until its base circle touches the outer cylinder 121, the outer cylinder 12 is pushed down by the force of the spring 16, and as a result, the inside of the hydraulic chamber 24 becomes negative pressure, so the check ball 26 opens. However, in the present invention, since a sufficient amount of oil is stored in the first oil reservoir chamber 38 while the oil is stopped, it is possible to replenish the oil pressure chamber 24 with an amount commensurate with the pressure drop. The engine fulfills its function, and the intake valve or exhaust valve operates properly, and there is no occurrence of seating noise. At the time of restart, lubricating oil from the hydraulic pump passes through the annular second chamber 40 from the oil supply hole 39, enters the first chamber 38 through the communication hole 45 in the peripheral part of the separator 36, and then passes through the central hole 361 of the separator 36. Head to Pushrod Seat 18. Due to this forcibly formed unidirectional oil flow, the air in the space above l at the time of stop is quickly exhausted, and the chamber 38 can be immediately filled with lubricating oil.

In the modified embodiment shown in FIG. 2, the separator 36 is formed of a single section-shaped member, and instead, by selecting the shape of the end face of the push rod sheet 18, a second oil reservoir similar to that shown in FIG. A chamber 40 is formed. In addition, the push rod seat 18 has an O-ring 70.
The second oil reservoir chamber 40 is fitted into the inner cylinder 16 through the inner cylinder 16 to obtain an airtight structure of the second oil reservoir chamber 40. Push rod seat 18 may be used in place of O-ring 70 for a tight fit. It is preferable to make the axial gap between the sheet 18 and the separator 36 as small as possible. Further, a deflector plate 72 is integrally formed facing the communication hole 45 of the separator 36. This is connected to the first oil reservoir chamber 3 from the second oil reservoir chamber 40 through the communication hole 45.
When oil is supplied to 8, air cells in the oil are prevented from moving toward the hydraulic chamber 24 from the oil supply hole 25. A similar deflector can be employed in the embodiment of FIG.

As described above, despite the simple structure of the present invention, it is possible to reliably secure the amount of remaining oil in the oil reservoir after the engine is stopped, prevent valve seat tapping noise when restarting the engine, and prevent valve seat wear. Problems such as valve damage can be prevented. In addition, since the structure is simpler than the conventional one, it has advantages such as ease of assembly and no need for advanced processing, resulting in cost reduction. Also,
With the present invention, it is possible to replenish oil into the oil reservoir chamber from the outside without disassembling it during service, which is an advantage compared to conventional valve lifters, especially the double check ball type, which was not possible. The air remaining above the liquid level l when stopped is quickly discharged at the time of startup along with the unidirectional flow of lubricating oil toward the push rod seat 18 formed by the separator 36, and is immediately filled with lubricating oil. be able to. Therefore, there is no possibility that air bubbles will be introduced into the hydraulic chamber 24 via the check valve 26.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a lifter according to a first embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a lifter according to a second embodiment. 12... Outer cylinder, 16... Inner cylinder, 24... Hydraulic chamber, 26... Check valve, 36... Separator,
38...First oil reservoir chamber, 39...Oil supply hole, 40...
2nd oil sump room, 45... communication hole.

Claims (1)

[Scope of utility model registration request] A valve lifter for an internal combustion engine comprising an outer cylinder and an inner cylinder arranged at an angle, a hydraulic chamber formed between the outer cylinder and the inner cylinder and an oil reservoir chamber formed within the inner cylinder, the oil chamber communicating with the hydraulic chamber by a check valve and also communicating with a hydraulic source via an oil supply hole drilled in the radial direction of the inner cylinder and an annular oil passage formed in the circumferential direction between the inner cylinder and the outer cylinder, the oil chamber being separated by a separator into a first chamber on the check valve side and a second chamber on the hydraulic source side, the separator having peripheral communication holes connecting the first chamber and the second chamber and a central hole communicating the first chamber with the push rod seat side, the communication hole being located approximately diametrically opposed to the oil supply hole of the inner cylinder across the central hole.