JP3674174B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve gear for an engine equipped with a hydraulic lash adjuster (hereinafter referred to as HLA).
[0002]
[Prior art]
Conventionally, in an engine valve operating device, it is possible to eliminate the hitting sound generated with the clearance in the valve operating mechanism and eliminate the need for adjustment work for the clearance. It is known as seen in prior examples such as Japanese Utility Model Publication Nos. 62-88804 and 62-76211.
[0003]
This HLA is basically provided with a slidable lifter on the back, to which hydraulic pressure is supplied via a check valve, and the tip of the lifter is urged by a lift spring against the shaft end of the valve. The valve is pushed in and opened when the check valve is closed as the camshaft rotates, and when the valve is closed, there is no gap between the lifter and the shaft end by the lift spring. So that the oil flows into the internal oil chamber and always operates without a clearance.
[0004]
In the HLA, as seen in the former publication of the previous example, a lifter is slidably inserted into a cylindrical sliding portion formed at one end of the rocker arm on the valve side, and the tip of the lifter is connected to the valve. There is one in which the hydraulic pressure is supplied to the inside of the lifter via a check valve. However, in this structure, since the lifter slides in direct contact with the wall surface of the sliding portion formed on the rocker arm, the wall surface needs to have wear resistance. In the case of forming aluminum with an aluminum alloy, it is necessary to perform a hardening treatment for that purpose, and it is difficult to obtain sufficient wear resistance.
[0005]
From this point, as in the latter case of the preceding example, a structure is adopted in which an outer cylinder is inserted into a mounting hole of a support base material such as a rocker arm and a lifter is slidably mounted inside the outer cylinder. ing.
[0006]
[Problems to be solved by the invention]
Thus, when an HLA having an outer cylinder as described above is provided, there is a problem in that a clearance is generated due to a change over time associated with long-term use and a hitting sound is generated.
[0007]
Specifically, when the fixing force of the outer cylinder decreases due to the aging of the lift spring that urges the lifter in the protruding direction or due to deterioration of the O-ring between the outer cylinder and the support base material over time The valve is closed and the pressing force against the lifter of the HLA is released, and before the oil from the hydraulic passage flows into the internal oil chamber, the outer cylinder is moved by the hydraulic pressure of the hydraulic passage. There may be a clearance between the bottom of the mounting hole of the support base material. At this time, when the valve is pressed through the HLA to open the valve next time, the outer cylinder may move so as to close the clearance, and a hitting sound may collide with the bottom of the fitting hole.
[0008]
The movement of the outer cylinder by the hydraulic pressure can be prevented by increasing the fixing force of the outer cylinder to the support base material by caulking or the like, but the structural restrictions and the sliding of the lifter with respect to the outer cylinder are hindered. The structure cannot be adopted .
[0009]
On the other hand, in the normal operation of the HLA, when the valve is opened against the valve spring, part of the oil confined in the HLA leaks from the gap between the lifter and the outer cylinder. The lifter is submerged by the amount corresponding to the amount of leakage, and when the valve is closed, the lifter projects and moves by the lift spring, and oil is introduced into the internal oil chamber to replenish the leaked oil. It works like that. The lift of the lifter (moving amount) tends to increase due to the wear of each part of the valve mechanism, such as the rocker arm bearing part, which is associated with the operation for a long time. Therefore, the lift amount of the lifter is also increased, and it is necessary to secure a sufficient lift amount even after a change with time, while making the HLA compact. If this lift amount is not secured, a clearance will be generated between the lifter tip and the valve shaft end, resulting in a hitting sound, and it is necessary to secure the necessary lift amount even when taking into account the crossing of dimensions of each part. There is.
[0010]
Further, in the stop state of the engine, part of the cylinder may be stopped at the timing of opening the valve, in this case Te odor by acting biasing force of the valve spring in the lifter of HLA, internal oil chamber The oil leaks from the gap between the lifter and the outer cylinder, and the lifter is in a state where the lift amount is zero. When the engine is restarted from this state, the larger the lift amount of the lifter, the more oil needs to be introduced into the internal oil chamber, and the introduction of oil from the hydraulic passage is delayed or the oil deteriorates. If the amount of air mixed into the oil is increased, the pseudo rigidity of the internal oil chamber is insufficient and the pressing force of the valve decreases, the follow-up performance of the valve lift to the cam rotation deteriorates, and the valve and valve seat There is a risk that a seating noise will occur.
[0011]
Therefore, in view of the above circumstances, the present invention is to provide a valve gear for an engine equipped with an HLA in which the above-described hitting sound and seating sound are not generated even after aging.
[0012]
[Means for Solving the Problems]
The valve operating apparatus for an engine of the present invention that has solved the above problems includes a lifter whose tip is in contact with the shaft end of an intake or exhaust valve so as to be slidable with respect to the outer cylinder, and the outer cylinder is fitted with a rocker arm . A hydraulic passage that fits into the mounting hole from the valve side and applies hydraulic pressure to the lifter through a through passage provided at the bottom of the outer cylinder is provided, and elastic between the outer cylinder and the lifter in the direction of separating both of them. Comprising a hydraulic spring adjuster interposing the body, comprising a leaf spring bent in a substantially U-shaped cross section when viewed from the side, while its lower end is locked to the valve side of the outer cylinder, The upper end is locked to the rocker arm, and a restricting member for preventing the movement of the outer cylinder to the valve side is provided .
[0013]
A lifter whose tip is in contact with the shaft end of the intake or exhaust valve is slidably mounted on the outer cylinder, and the outer cylinder is fitted from the valve side into a fitting hole formed at one end of the rocker arm. In addition, a hydraulic passage that applies hydraulic pressure to the lifter via a through passage provided at the bottom of the outer cylinder, and an elastic body is interposed between the outer cylinder and the lifter in a direction to separate them from each other. An adjuster is provided, and the lift amount when the valve is closed at the time of initial assembly of the lifter with respect to the outer cylinder is set to a lift amount smaller than ½ of the maximum lift amount of the lifter with respect to the outer cylinder. May be .
[0014]
In particular, the maximum lift amount is desirably set as a lower limit value in dimensional tolerance. And the setting of the lift amount at the time of initial assembly of the lifter is adjusted by the depth of the fitting hole for fitting the outer cylinder, or the bottom of the fitting hole for fitting the outer cylinder and the outer cylinder end surface This can be done by adjusting with an adjustment shim.
[0015]
【The invention's effect】
According to the valve operating apparatus for an engine of the present invention as described above, by providing the regulating member for preventing movement of the valve side of the outer cylinder is locked to the outer tube and the supporting base material in the HLA, valve After the seating, the lifter moves by the urging force of the elastic body and the hydraulic pressure is introduced from the hydraulic passage, and the outer cylinder itself against the support base material due to the aging of each part such as the elastic body sag and O-ring deterioration. Even if it becomes easy to move, the movement is restricted by the restriction member, and the outer cylinder itself moves relative to the support base material by the hydraulic pressure acting from the hydraulic passage, so that no clearance is formed at the bottom of the fitting hole. The hitting sound caused by this movement can be prevented, and the expected function of the HLA can be maintained.
[0016]
In particular, in the case of using a U-shaped leaf spring as a regulating member, one end is locked to the outer cylinder and the other end is locked to the support base material, and after the HLA is assembled by preventing the movement of the outer cylinder Mounting is easy and the locking performance can be improved.
[0017]
Further, provided with the HLA to one end of Russia Kkaamu, the lift amount at the time of valve opening during initial assembly to the outer tube of the lifter, by setting a smaller lift amount than the half of the maximum lift amount, of the lifter Even when the lift movement to the valve side has a large margin, and the lift amount of the lifter increases due to wear of the rocker arm bearing part as the engine operates, or the pseudo rigidity decreases due to deterioration of the oil, Following this, the lifter moves to ensure followability of the valve lift with respect to the rotation of the cam, and the occurrence of seating noise between the valve and the valve seat can be prevented.
[0018]
Furthermore, when the maximum lift amount is set as a lower limit value in the dimensional tolerance, it is possible to further secure the amount of movement of the lifter with respect to the change with time. The lift amount during the initial assembly of the lifter can be set by adjusting the depth of the fitting hole, and an adjustment shim is interposed between the bottom of the fitting hole and the end surface of the outer cylinder. It can be done easily.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on one embodiment shown in the drawings. FIG. 1 is a sectional front view of an essential part of an overhead cam type engine valve operating device, and FIG. 2 is a sectional view of an HLA portion.
[0020]
A camshaft 2 is rotatably supported on a cylinder head 1 of the engine. The camshaft 2 is rotationally driven in synchronization with an engine crankshaft (not shown), and is provided with a cam surface 2a having a predetermined shape. . A rocker shaft 3 extending in parallel with the camshaft 2 is supported on the cylinder head 1, and a rocker arm 4 is supported on the rocker shaft 3 so as to be swingable. One end 4a of the rocker arm 4 (the left end in the figure) Part) is in contact with the cam surface 2 a of the camshaft 2, and the rocker arm 4 is swung by a predetermined angle by the rotation of the camshaft 2.
[0021]
On the other hand, the other end portion 4b (right end portion in the figure) of the rocker arm 4 is connected to a shaft of an intake or exhaust valve 7 for opening and closing an intake or exhaust port 6 via a hydraulic lash adjuster 5 (HLA) described later. The end 7a is in contact with the rocker arm 4, and the valve 7 is pressed against the urging force of the valve spring 8 that urges the valve 7 in the valve closing direction as the rocker arm 4 swings. It is configured to be seated on the valve seat 9 with an urging force of 8 and to open and close at a predetermined timing.
[0022]
The other end 4b of the rocker arm 4 is provided with a fitting hole 11 having a large diameter on the side facing the valve 7, and has a diameter continuous to the bottom 11a of the fitting hole 11 through a stepped portion. A small hydraulic passage 12 is provided. The hydraulic passage 12 further communicates with the central oil passage 3a of the rocker shaft 3 through an oil hole 4c provided in the rocker arm 4 and is supplied with hydraulic pressure.
[0023]
An HLA 5 is fitted into the fitting hole 11 of the rocker arm 4, and an outer cylinder 15 of the HLA 5 is fitted into the fitting hole 11. As shown also in FIG. 5, the outer cylinder 15 has a bottomed cylindrical shape with an open front end (lower end), a through passage 15 a is opened at the center of the bottom, and a bottom surface 15 b extends from the fitting hole 11. It is fitted until it comes into contact with the bottom 11a. A plunger-like lifter 16 is slidably inserted into the outer cylinder 15, and a tip end portion 16 a of the lifter 16 comes into contact with the shaft end portion 7 a of the valve 7.
[0024]
An oil chamber 18 that expands and contracts corresponding to the movement of the lifter 16 is formed between the rear portion of the lifter 16 and the bottom of the outer cylinder 15, and the lifter 16 is protruded into the oil chamber 18 in the protruding direction, that is, A lift spring 17 as an elastic body that urges the oil chamber 18 in an expanding direction is retracted, and a check valve 20 is provided by a ball that opens and closes the through passage 15a. Energized in the valve closing direction.
[0025]
An O-ring 23 is attached to the outer peripheral portion of the outer cylinder 15 to provide a seal with the inner peripheral surface of the fitting hole 11, and the outer cylinder 15 above the O-ring 23 has an inner and outer periphery. A return passage 24 that penetrates is provided so that oil leaking between the lifter 16 and the outer cylinder 15 returns to the hydraulic passage 12 side.
[0026]
A locking cap 25 is fixed to the distal end portion of the outer cylinder 15, and the inner edge of the locking cap 25 is locked to the step portion 16 c of the lifter 16 so that the most protruding position is restricted. Further, the rear end portion 16b of the lifter 16 abuts on the engaging step portion 15c on the inner surface of the outer cylinder 15, and the last retracted position is restricted.
[0027]
In addition to the mounting of the HLA 5 as described above, the outer cylinder 15 is locked to both the outer cylinder 15 and the rocker arm 4 as a support base material, and the outer cylinder 15 moves in the protruding direction toward the valve 7 side. A regulating member 10 is installed by a leaf spring that regulates the above.
[0028]
As shown in FIG. 3, the regulating member 10 is formed so that the leaf spring is bent in a substantially U shape when viewed from the side, and the lower end portion 10 a is locked to the distal end portion of the outer cylinder 15. An opening 10c through which the tip end 16a of the lifter 16 is inserted is provided at the center of the lower end 10a, and the upper end 10b extends in a fork-like manner on both sides and extends above the fitting hole 11 of the other end 4b of the rocker arm 4. It is provided so as to be engaged with the outer step portion 4d, and the tip end portion of the upper end portion 10b is bent upward. In the free state, the regulating member 10 is provided so that the interval between the lower end portion 10a and the upper end portion 10b is narrowed, and the interval between the lower end portion 10a and the upper end portion 10b is widened as shown in FIG. Thus, the elastic force acts to urge the outer cylinder 15 in the immersion direction.
[0029]
In the mounting process of FIG. 4, first, the regulating member 10 is slanted from below, and the lower end portion 10 a is locked to the tip of the outer cylinder 15 of the HLA 5. 4d is pushed up and mounted.
[0030]
Further, in the HLA 5, FIG. 5A shows the range of movement of the lifter 16, and the state shown by the solid line is the most protruding position (maximum lift position) where the outer peripheral step portion 16c of the lifter 16 is locked to the locking cap 25. From this state, as indicated by a chain line, the range A in which the rear end portion 16b of the lifter 16 moves to the last retracted position (the lift amount zero position) where the rear end portion 16b of the outer cylinder 15 is in contact with the inner peripheral locking step portion 15c is lifter. The maximum lift amount is 16.
[0031]
5B, when the valve 7 is in the closed state in which the valve 7 is seated on the valve seat 9, the valve 7 is in contact with the shaft end 7a and stopped. The initial assembly position of the lifter 16 is set so that the lift amount B moved from the last retracted position of the lifter 16 is in a range smaller than ½ of the maximum lift amount A. In other words, the allowable lift amount in the protruding direction of the lifter 16 is set to be larger than 1/2 of the maximum lift amount A.
[0032]
The maximum lift amount A is affected by the dimensional tolerance of the outer cylinder 15, the lifter 16, and the locking cap 25 of the HLA 5. The value of 1/2 of the maximum lift amount A is the dimensional tolerance. Is defined by the lower limit value.
[0033]
Further, the initial assembly lift amount B of the lifter 16 is a fixed position where the seating position of the valve 7 is defined by the shapes of the valve 7 and the valve seat 9, and therefore the fitting hole 11 of the rocker arm 4 of the outer cylinder 15. It can be adjusted by the fitting position with respect to Specifically, as shown in FIG. 6, the initial assembly state of the lifter 16 can be set by adjusting the depth L of the fitting hole 11.
[0034]
For the same reason, the lift amount B can be adjusted by inserting an adjustment shim 30 between the bottom 11a of the fitting hole 11 and the bottom surface 15b of the outer cylinder 15. Further adjustment is possible by changing the thickness of the adjusting shim 30. For example, when the adjustment shim 30 having the thickness d is interposed, the outer cylinder 15 moves in the protruding direction by this d, so that the range of the original maximum lift amount A is the same. The lift amount B is changed to a value as small as B '.
[0035]
Explaining the operation of the valve mechanism as described above, the basic operation of the HLA 5 is that when the protrusion of the cam surface 2 a comes into sliding contact with the one end 4 a of the rocker arm 4 as the cam shaft 2 rotates, the rocker arm 4 swings so as to rotate clockwise in FIG. 1, and the other end 4b urges the shaft end 7a of the valve 7 via the HLA 5 in the valve opening direction. In this case, in the HLA 5, the lifter 16 is retracted by a small amount until the check valve 20 is securely closed, the oil chamber 18 is sealed, and the movement of the lifter 16 is stopped. The lifter 16 resists the valve 7 against the valve spring 8. To move in the valve opening direction.
[0036]
When the camshaft 2 rotates and the protrusion of the cam surface 2 a elapses after opening for a predetermined period, the rocker arm 4 rotates in the reverse direction and the valve 7 is closed by the urging force of the valve spring 8. When the valve 7 is seated on the valve seat 9, the urging force of the valve spring 8 does not act on the lifter 16 of the HLA 5, and this lifter 16 is urged in the protruding direction by the internal lift spring 17 to lift and move. 20 opens and hydraulic pressure is supplied from the hydraulic passage 12 to the internal oil chamber 18 through the through passage 15a.
[0037]
In the above operation, during the period in which the valve 7 is pushed down and opened, the pressure in the oil chamber 18 rises and oil leaks through the gap between the lifter 16 and the outer cylinder 15. Also, the oil chamber 18 is replenished, and when the valve 7 is seated, the tip end portion 16a of the lifter 16 always abuts against the shaft end portion 7a of the valve 7 so that no clearance is generated in this portion. Accordingly, the displacement of the portion supporting the rocker arm 4 due to the wear of the rocker shaft 3 is adjusted and absorbed by the movement of the lifter 16.
[0038]
And in addition to the above basic operations, the installation of the above-described regulating member 10 has the following anti-sounding effect. The hydraulic pressure in the hydraulic passage 12 acts so as to flow into the oil chamber 18 inside the outer cylinder 15 through the through passage 15 a and also acts on the bottom surface 15 b of the outer cylinder 15 to remove the outer cylinder 15 from the fitting hole 11. The outer cylinder by the hydraulic pressure of the hydraulic passage 12 when the valve 16 is urged so as to protrude and the flow into the oil chamber 18 is delayed at the time of valve seating when the urging force from the valve 7 is reduced with respect to the lifter 16. The movement of the outer cylinder 15 is prevented by restricting the movement of the outer cylinder 15 by the restriction member 10, by the protrusion movement of 15.
[0039]
When a clearance is generated between the bottom surface 15 b of the outer cylinder 15 and the bottom portion 11 a of the fitting hole 11, the rocker arm 4 swings to press the shaft end portion 7 a of the valve 7 in order to open the valve 7. At that time, the lifter 16 is immersed by the pressing, and the outer cylinder 15 moves backward so as to eliminate the clearance, and a hitting sound is generated in which the outer cylinder bottom surface 15b and the bottom portion 11a of the fitting hole 11 collide. However, the regulation member 10 prevents the hitting sound from occurring.
[0040]
Further, the HLA 5 as described above causes a displacement in the direction in which the lift amount of the lifter 16 increases depending on changes over time such as wear of the rocker shaft 3 and wear of the cam surface 2a or one end of the rocker arm 4. In the initial assembled state, the lifter 16 is set with a margin for displacement in the protruding direction, so that a predetermined adjustment function of the HLA 5 can be obtained even after long-time operation. It is possible to effectively prevent the occurrence of a hitting sound due to the clearance between the shaft end portion 7a of the valve 7 without being adjusted to the maximum lift position and further adjustment.
[Brief description of the drawings]
FIG. 1 is a sectional front view of an essential part of an engine valve operating apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view of an essential part of a rocker arm including a hydraulic lash adjuster. Fig. 4 is a plan view showing the state before mounting. Fig. 4 is a front view showing the mounting process of the regulating member. Fig. 5 is a cross-sectional view showing the range of movement of the lifter of the hydraulic lash adjuster. Sectional diagram showing the adjustment of the material
1 Cylinder head 2 Camshaft 3 Rocker shaft 4 Rocker arm (support base material)
5 Hydro lash adjuster (HLA)
7 intake or exhaust valve 7a shaft end 8 valve spring 10 regulating member 11 fitting hole 11a bottom 12 hydraulic passage 15 outer cylinder 15a through passage 16 lifter 17 lift spring (elastic member)
18 Oil chamber 20 Check valve 25 Locking cap 30 Shim for adjustment

Claims (5)

A lifter whose tip is in contact with the shaft end of the intake or exhaust valve is slidably mounted with respect to the outer cylinder, and the outer cylinder is fitted into the fitting hole of the rocker arm from the valve side. A hydraulic passage adjuster is provided with a hydraulic passage that applies hydraulic pressure to the lifter through a through passage provided at the bottom of the cylinder, and an elastic body is interposed between the outer cylinder and the lifter in a direction to separate them. In the engine valve mechanism provided,
It consists of a leaf spring bent in a substantially U-shaped cross section when viewed from the side, and its lower end is locked to the valve side of the outer cylinder, while its upper end is locked to the rocker arm. A valve operating apparatus for an engine, characterized in that a restricting member for preventing movement of the cylinder to the valve side is provided . Characterized in that the lift amount at the time of closing of the initial assembly time of the valve with respect to the outer cylinder before Symbol lifter was set to a smaller lift amount than the half of the maximum lift amount of sliding relative to the outer cylinder of the lifter The valve operating apparatus for an engine according to claim 1 . The valve operating apparatus for an engine according to claim 2 , wherein the maximum lift amount is a lower limit value in a dimensional tolerance. The engine valve gear according to claim 2 , wherein the lift amount at the time of initial assembly of the lifter is adjusted by the depth of the fitting hole into which the outer cylinder is fitted. The lift amount at the time of initial assembly of the lifter is adjusted by interposing an shim for adjustment between a bottom portion of a fitting hole for fitting the outer cylinder and an outer cylinder end surface. 2. The valve operating apparatus for an engine according to 2 .

Images