JPH05272312A - Oil feeding device to automatic valve clearance adjusting mechanism - Google Patents

Abstract

PURPOSE:To provide an oil feeding device to an automatic valve clearance adjusting mechanism to prevent the valve closing time valve opening caused by pump-up of the automatic valve clearance adjusting mechanism. CONSTITUTION:In an oil feeding device to an automatic valve clearance adjusting mechanism 10 which is provided with an oil pressure chamber 13 and is interposed between a valve opening/closing cam 7a and a valve 8 and adjusts valve clearance created between the valve opening/closing cam 7a and the valve 8 due to at oil pressure supplied to the oil pressure chamber 13, the oil feeding device to the automatic valve clearance adjusting mechanism 10 is provided with a prohibiting means 24 to prohibit supply of the oil pressure to the oil pressure chamber 13 during a prescribed period in the last period of an area where at least a base circle of the valve opening/closing cam 7a comes into contact with the automatic valve clearance adjusting mechanism 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic valve clearance for preventing valve opening at valve closing due to extension of the automatic valve clearance adjustment mechanism (hereinafter referred to as pump up) caused by unnecessary oil supply to a hydraulic chamber. The present invention relates to an oil supply device for an adjustment mechanism.

[0002]

2. Description of the Related Art Conventionally, in order to automatically adjust a valve clearance generated between a valve opening / closing cam and an intake / exhaust valve of an internal combustion engine, a valve clearance automatic adjustment is performed between the valve opening / closing cam and the intake / exhaust valve. It has a mechanism. This automatic valve clearance adjustment mechanism is disclosed in, for example, Japanese Patent Laid-Open No. 59-8721.
As shown in Japanese Patent Application Laid-Open No. 2 (1998), a plunger slidably arranged with respect to a main body body, a hydraulic chamber formed between the plunger and the main body body, to which oil is supplied, and a hydraulic chamber When the valve rush of the valve occurs, the plunger spring is mounted, and while the plunger is extended by the urging force of the plunger spring, oil is supplied to the hydraulic chamber to bring the plunger into contact with the upper end of the valve stem. It is known that the valve lash of the valve is adjusted to zero in order to reduce the valve operating noise and improve the quietness.

In such a valve clearance automatic adjusting mechanism, oil is supplied from the oil supply passage during the entire period when the base circle of the cam is in contact with the upper surface of the main body. Therefore, when the valve closes while the internal combustion engine is operating at high speed, when the body bounces against the elastic force of the valve spring that presses the upper end of the valve stem against the lower surface of the plunger, the body of the main body enters the hydraulic chamber. There is a problem that pump-up occurs due to the action of both the resilience of the plunger spring and the hydraulic pressure supplied. In order to solve this problem, Japanese Utility Model Laid-Open No. 59-76707 discloses prohibiting the supply of hydraulic pressure into the hydraulic chamber for a while after the contact of the main body with the base circle of the cam immediately before the valve is closed. Even if a bounce occurs, the expansion of the plunger associated with the bounce is performed only by the elastic force of the plunger spring, and the pump up of the automatic valve clearance adjustment mechanism is significantly reduced.

[0004]

By the way, there are demands for higher engine output and lower fuel consumption as demands for the present engine. In order to pursue these demands, a variable valve timing mechanism is adopted, and intake air is excessively high. Supply and reduction of mechanical loss are being carried out. Therefore, there are the following effects on the valve train having the automatic valve clearance adjustment mechanism.

Explaining with reference to FIG. 4, when a hydraulically controlled variable valve timing mechanism is adopted, high hydraulic pressure is applied in consideration of responsiveness. Generally, since the hydraulic path 1 to the automatic valve clearance adjusting mechanism t is common to the hydraulic path of the variable valve timing mechanism, the hydraulic pressure applied to the automatic valve clearance adjusting mechanism t is also high and the ejection force A of the plunger 2 is large. .. Further, the back pressure of the valve 3 rises as the intake air becomes supercharged, and the pressing force B of the valve 3 increases. Further, there is a tendency that the set loads C and D of the plunger spring 4 and the valve spring 5 when the valve is closed are reduced due to a demand for reduction of mechanical loss. Therefore, the relationship between the force K in the valve opening direction and the force H in the valve closing direction of the valve 3 at the time of closing in the intake stroke or the exhaust stroke is as follows. Here, E is a force in the valve closing direction from the combustion chamber side, and this force is substantially equal to zero in the intake stroke or the exhaust stroke. Force K in the valve opening direction: (A + B + C) ≧ Force H in the valve closing direction: (D + E)

As a result, the force in the valve closing direction of the valve at the time of closing in the intake stroke or the exhaust stroke is almost equal to the force in the valve opening direction, or in the worst case, becomes smaller, so that in the intake stroke or the exhaust stroke. It is difficult to keep the valve closed.

In such a valve clearance automatic adjusting mechanism of an engine, a pump-up phenomenon as shown by p in FIG. 3 has occurred. The present inventors have found out that the pump-up p does not occur only during high-speed operation as in the prior art but also during low-speed operation, and therefore occurs according to the following principle.

That is, when the camshaft makes an eccentric motion within a predetermined clearance provided between the cam bearing portion and the camshaft journal when the valve is closed in the intake stroke or the exhaust stroke, the above-mentioned ejecting force of the plunger. Since A is large, the valve clearance automatic adjustment mechanism is sensitive to the vertical movement of the eccentric movement, and the amount of the operation is generated as pump-up.

An object of the present invention is to open a valve when a valve is closed, which is caused by pumping up of the automatic valve clearance adjusting mechanism, in a valve train system provided with an automatic valve clearance adjusting mechanism, which pursues high engine output and low fuel consumption. An object of the present invention is to provide an oil supply device for a valve clearance automatic adjustment mechanism capable of preventing the above.

[0010]

In order to achieve the above object, the constitution of the present invention is as follows.

According to the first aspect, a hydraulic chamber is provided,
A device for supplying oil to a valve clearance automatic adjusting mechanism which is interposed between a valve opening / closing cam and a valve and adjusts a valve clearance generated between the valve opening / closing cam and the valve by an oil pressure supplied to the hydraulic chamber. In the above, a means for prohibiting the supply of the hydraulic pressure to the hydraulic chamber at least during a predetermined period at the end of the region where the base circle of the valve opening / closing cam is in contact with the automatic valve clearance adjusting mechanism is provided. To do.

According to the second aspect, in the oil supply device for the automatic valve gap adjusting mechanism according to the first aspect, the period for prohibiting the supply of hydraulic pressure to the automatic valve gap adjusting mechanism by the prohibiting means is started. Is immediately after the valve is closed, and is ended until the end of the period in which the base circle of the valve opening / closing cam is in contact with the valve gap automatic adjustment mechanism.

According to the third aspect of the present invention, in the oil supply device for the automatic valve clearance adjusting mechanism according to the first aspect, the start of the period during which the supply of hydraulic pressure to the automatic valve clearance adjusting mechanism by the prohibiting means is prohibited. From immediately after the valve is closed, and the end is extended until just before the valve acceleration becomes positive when the valve speed in the valve opening direction is positive. Only the hydraulic pressure is supplied to the hydraulic chamber.

[0014]

According to the structure described in claim 1, at least during the predetermined period at the end of the region where the base circle of the valve opening / closing cam is in contact with the valve clearance automatic adjusting mechanism, the automatic valve clearance adjusting mechanism operates. Supply of hydraulic pressure to the hydraulic chamber is prohibited. Therefore, even if the valve clearance automatic adjustment mechanism pumps up when the valve is closed,
Oil leaks from the hydraulic chamber of the valve clearance automatic adjustment mechanism,
Pump up is reduced at the end of valve closure.

According to the second aspect of the present invention, from immediately after the valve is closed to the end of the period in which the base circle of the valve opening / closing cam is in contact with the automatic valve clearance adjusting mechanism, that is, the entire period in which the valve is closed. The supply of hydraulic pressure to the hydraulic chamber of the automatic valve clearance adjustment mechanism is prohibited. Therefore, it is possible to reliably reduce the pump up of the automatic valve clearance adjustment mechanism that occurs when the valve is closed.

According to the third aspect of the invention, when the valve speed in the valve opening direction is positive when the supply of the hydraulic pressure to the hydraulic chamber of the automatic valve clearance adjusting mechanism is made to be positive immediately after the valve is closed, the valve is closed. Extension is prohibited until just before the acceleration becomes positive. In other words, during medium-high speed operation and during a period when the valve acceleration is negative, the valve tends to jump from the automatic valve clearance adjustment mechanism in the valve opening direction due to its inertial force. Therefore, it is possible to reliably reduce the phenomenon in which the jump amount occurs as a pump-up.

Further, the prohibition period of the hydraulic pressure supply to the hydraulic chamber is set from immediately after the valve is closed to immediately before the valve acceleration becomes positive when the valve is closed, so that the eccentric movement of the camshaft can be performed without complicating the prohibiting means. And the pump up caused by the jump of the valve can both be reduced,
Furthermore, if the hydraulic pressure is supplied to the hydraulic chamber only during the remaining period, the automatic valve clearance automatic adjustment function originally intended for the automatic valve clearance adjustment mechanism will not be impaired.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

An engine equipped with this automatic valve clearance adjustment mechanism employs a variable valve timing mechanism in order to pursue high engine output and low fuel consumption, high intake air supercharging and reduction of mechanical loss. There is. That is, as described above, the hydraulic path to the automatic valve clearance adjusting mechanism is the same as the hydraulic path of the variable valve timing mechanism (not shown), so that the hydraulic pressure applied to the automatic valve clearance adjusting mechanism is high and the projecting force A of the plunger is large. Become. Further, as the intake air becomes supercharged, the back pressure of the valve rises and the pushing force B of the valve increases. Further, in order to reduce mechanical loss, the set loads C and D of the plunger spring and the valve spring when the valve is closed are set to be as small as possible. (See FIG. 4) Therefore, the force in the valve closing direction of the valve at the time of closing in the intake stroke or the exhaust stroke becomes extremely small. Here, the automatic valve clearance adjusting mechanism of the present invention will be described.

Reference numeral 6 denotes a cylinder head, 7a denotes a valve opening / closing cam which is arranged above the cylinder head 6 and rotates in synchronization with the engine, and 7 denotes a cam shaft on which the valve opening / closing cam 7a is formed. Shaft journal 7b
Is rotatably supported by a bearing portion 7d formed by the cylinder head 6 and the cam cap 7c with a predetermined clearance. Reference numeral 8 denotes a valve disposed below the valve opening / closing cam 7a, and a hollow that is slidably fitted in the insertion hole 6a of the cylinder head 6 between the valve opening / closing cam 7a and the valve 8. The bucket 9 and the automatic valve clearance adjusting mechanism 10 located inside the bucket 9 are arranged, and the valve 8 is moved up and down through the automatic valve clearance adjusting mechanism 10 to open and close.

The automatic valve clearance adjusting mechanism 10 is provided with a hollow main body 11 suspended and fixed to the central portion of the inner wall of the bucket 9, and is vertically slidably arranged on the main body 11. A plunger 12 facing the upper end of the stem 8a of the stem 8a, and a hydraulic chamber 13 is formed below the main body 11 by the main body 11 and the plunger 12. The hydraulic chamber 13 is formed by the hydraulic chamber 13.
The inside of the main body 11 is communicated with via a communication port 11a opened at the bottom. A plunger spring 14 is compressed inside the hydraulic chamber 13, and oil flows from the inside of the main body 11 to the hydraulic chamber 13 at a portion of the hydraulic chamber 13 facing the communication port 11a. A check valve 15 that allows only the above is arranged. The check valve 15 includes a check ball 15a seated on the communication port 11a and a ball spring 15b urging the check ball 15a in the seating direction.

Further, an oil reserve chamber 17 is formed inside the bucket 9 by the bucket 9 and a guide member 16 for guiding the plunger 12, and the inside of the reserve chamber 17 is on the side of the bucket 9. The main body 1 is communicated with the oil passage 19 of the cylinder head 6 through the oil inlet 18a of the annular groove 18 provided and through the oil outlet 20 provided on the inner wall of the head of the bucket 9.
1 is connected to the inside of the cylinder head 6, and after the oil from the oil passage 19 of the cylinder head 6 is supplied to the reserve chamber 17,
The oil is supplied from the inside of the main body 11 to the hydraulic chamber 13 via the check valve 15. Therefore, when the valve rush occurs in the valve 8, the plunger spring 14 causes the plunger 12 to extend, and the pressure in the hydraulic chamber 13 decreases due to the extension, so that the oil in the reserve chamber 17 is removed from the main body. By opening the check valve 15 from the inside of the body 11 and flowing into the hydraulic chamber 13, the plunger 12 is brought into contact with the upper end of the stem 8a of the valve 8 and the valve lash of the valve 8 is adjusted to zero. It is configured.

Here, as shown in FIG. 3, the annular groove 18 closes the valve 8 from a point a at which the valve acceleration when the valve 8 is closed when the valve speed in the valve opening direction is positive becomes negative to positive. It is formed so as to communicate with the oil passage 19 in a period Y2 immediately after the point b.

On the other hand, an oil passage 21 is formed inside the camshaft 7 along the axis of the camshaft 7.
1 is an oil passage 22 extending in the radial direction of the camshaft 7.
Through the inner peripheral surface of the bearing portion 7d.

Here, from the point a on the inner peripheral surface of the bearing portion 7d, as shown in FIG. 3, when the valve velocity in the valve opening direction is positive, the valve acceleration when the valve 8 is closed changes from negative to positive. Point a'a little before, point b just after the valve 8 is closed
Oil groove 2 communicating with the oil passage 22 during the period Y up to
3 is formed, and the oil passage 19 described above communicates with the oil groove 23. Further, the oil passage 22 and the oil groove 23 do not communicate with each other during a period X other than the above period Y in one cycle of the camshaft 7. That is, the oil passage 22 and the oil groove 23 are communicated with each other at a point a ', the oil passage 19 and the annular groove 18 are communicated with each other at a point a, and the above communication is blocked at a point b. Therefore,
The period during which the oil is supplied into the hydraulic chamber 13 is between the points a and b (period Y2) where the above-mentioned communication is performed, and the supply of oil into the hydraulic chamber 13 is prohibited during the period other than that. become. With the above configuration, a prohibiting means 24 for prohibiting the hydraulic pressure supply to the hydraulic chamber 13 is formed. The operation will be described below.

The bucket 9 follows the valve opening / closing cam 7a as the cam shaft 7 rotates in the F direction, and moves up and down in the insertion hole 6a of the cylinder head 6. by this,
The valve 8 opens and closes. Since oil is supplied to the oil passage 21 of the camshaft 7 by a hydraulic pump or the like (not shown), the bucket 9 is closed by the valve opening / closing cam 7a.
3 to 4 from the position corresponding to the point a in FIGS. 3 and 4 on the nose 7e of FIG.
The period Y2 in which the position corresponding to the point b in the middle is in contact
The annular groove 18 and the oil passage 19 communicate with each other, the oil groove 23 and the oil passage 22 communicate with each other, and the oil is supplied into the hydraulic chamber 13 through the oil inlet port 18a of the annular groove 18. As a result, the bucket 9 operates the plunger 12 to automatically adjust the valve clearance.

Further, the bucket 9 is a cam 7a for opening and closing the valve.
In the nose 7e, the oil passage 19 and the annular groove 18 do not communicate with each other during the period Y1 in which the nose 7e is in contact from the position corresponding to the point a ′ in FIGS. 3 and 4 to the position corresponding to the point a.
In addition, the oil groove 23 and the oil passage 22 communicate with each other, the oil flows out from the oil passage 19 into the insertion hole 6a, and the outflowed oil is supplied for lubrication between the bucket 9 and the insertion hole 6a. Since the oil flows out to the insertion hole 6a, it is possible to improve the initial responsiveness when the hydraulic pressure is applied to the hydraulic chamber 13.

As described above, no oil is supplied into the hydraulic chamber 13 during the period Z from immediately after the valve 8 is closed to immediately before the valve acceleration when the valve 8 is closed becomes positive. This period Z includes the entire period Z1 in which the valve lift is zero as shown in FIG. 3, and particularly in the valve 8 at the time of closing in the intake stroke or the exhaust stroke, the bearing portion 7
Although the camshaft 7 is likely to cause an eccentric motion within a predetermined clearance provided between d and the camshaft journal 7b, since the oil groove 23 and the oil passage 19 are not in communication with each other, No hydraulic pressure is acting on. Therefore, even if the camshaft 7 undergoes eccentric movement, the extension of the plunger 12 due to the eccentric movement, especially in the vertical direction, causes the plunger spring 14 to extend.
It is performed only by the resilience of. As a result, the automatic valve clearance adjustment mechanism 10 does not operate sensitively, and even if it is operated only by the elastic force of the plunger spring 14, it does not occur as a pump up, and it is possible to reliably prevent the pump up. Further, during the remaining period Z2, the valve 8
During the period from the start of the lift to immediately before the valve acceleration becomes positive when the valve 8 is closed as shown in FIG. 3, and during the period when the engine is operating at high speed and the valve acceleration is negative, the inertia of the valve 8 is increased. Although it is a period in which a phenomenon in which the valve clearance automatic adjusting mechanism 10 jumps in the valve opening direction due to force is likely to occur, the oil passage 19 and the annular groove 18 are not in communication with each other, so that hydraulic pressure is acting in the hydraulic chamber 13. Absent. Therefore, it is possible to reliably reduce the phenomenon in which the jump amount occurs as a pump-up.

In the above embodiment, in order to prevent the valve clearance automatic adjusting mechanism 10 from pumping up, the above-mentioned period Z is set.
Although the oil supply to the hydraulic chamber 13 is prohibited, if the oil supply is prohibited at least during the predetermined period s at the end of the period Z1, the pump-up effect can be obtained.

In the above embodiment, the case where the present invention is applied to the bucket type automatic valve clearance adjusting mechanism has been described, but it is needless to say that the present invention can be similarly applied to a rocker arm built-in type.

[0031]

As described above, according to the oil supply device for the automatic valve clearance adjusting mechanism of the present invention, at least the predetermined value at the end of the region where the base circle of the valve opening / closing cam is in contact with the automatic valve clearance adjusting mechanism. Since the supply of hydraulic pressure to the hydraulic chamber of the valve clearance automatic adjustment mechanism is prohibited during the period, even if the valve clearance automatic adjustment mechanism pumps up when the valve is closed, Oil is leaked and pump up can be reduced at the end of valve closure.

Further, according to the present invention, if the supply of the hydraulic pressure to the hydraulic chamber of the automatic valve clearance adjusting mechanism is prohibited during the entire period of the valve closing, the automatic valve clearance adjusting mechanism which is generated when the valve is closed is provided. Pump-up can be reliably reduced.

Further, according to the present invention, if the supply of the hydraulic pressure to the hydraulic chamber of the automatic valve clearance adjusting mechanism is prohibited during a period from immediately after the valve is closed to when the valve is at the maximum speed when the valve is closed, the prohibition means is provided. It is possible to prevent both pump-up caused by the eccentric movement of the camshaft and pump-up caused by the jump of the valve without complicating. If the hydraulic pressure is supplied to the hydraulic chamber only during the remaining period, the automatic valve clearance automatic adjustment function originally intended for the automatic valve clearance adjustment mechanism will not be impaired.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of an oil supply device for an automatic valve clearance adjusting mechanism according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of the oil supply device for the automatic valve clearance adjustment mechanism of FIG.

3A is a characteristic diagram of a valve lift, FIG. 3B is a velocity characteristic diagram of a valve lift, FIG. 3C is an acceleration characteristic diagram of a valve lift, and FIG. 3D is a hydraulic characteristic diagram of a hydraulic chamber. Is.

FIG. 4 is a front view showing a partial cross section showing a use state of an automatic valve clearance adjusting mechanism for an engine of the present invention.

[Explanation of symbols]

Valve opening / closing cam: 7a, valve: 8, hydraulic chamber: 13,
Automatic valve clearance adjustment mechanism ... 10, prohibiting means ... 24.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Shimizu 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (3)

[Claims] 1. A hydraulic chamber, which is interposed between a valve opening / closing cam and a valve, and adjusts a valve clearance generated between the valve opening / closing cam and the valve by a hydraulic pressure supplied to the hydraulic chamber. In the oil supply device for the automatic valve clearance adjustment mechanism, the supply of hydraulic pressure to the hydraulic chamber is prohibited at least during a predetermined period at the end of the region where the base circle of the valve opening / closing cam is in contact with the automatic valve clearance adjustment mechanism. A device for supplying oil to the automatic valve gap adjustment mechanism, characterized by being provided with a prohibiting means 2. The method according to claim 1, wherein the period for prohibiting the supply of hydraulic pressure to the automatic valve clearance adjusting mechanism of the prohibiting means is started immediately after the valve is closed, and the end thereof is determined by the base circle of the valve opening / closing cam. Until the end of the period of contact with the valve clearance automatic adjustment mechanism. 3. The method according to claim 1, wherein the period for prohibiting the supply of hydraulic pressure to the automatic valve clearance adjusting mechanism of the prohibiting means is started immediately after the valve is closed, and is ended when the valve speed in the valve opening direction is positive. In this case, the hydraulic pressure is extended to the time immediately before the valve acceleration becomes positive when the valve is closed, and the hydraulic pressure is supplied to the hydraulic chamber only during the period immediately after the valve acceleration and immediately before the valve is closed.