JP2004084627A - Valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve mechanism capable of forming an optimum valve pitch. <P>SOLUTION: In the valve mechanism for an engine, the valve is closably driven through a rocker bridge liftably mounted to a cylinder head. A rocker arm abutting part is supported on an upper surface of a piston liftably fitted to the inside of a cylinder part formed on the rocker bridge upper surface side and an oil chamber is formed on a lower surface of the piston. A guide pin standingly provided on the cylinder head is liftably inserted to a guide hole provided on a leg part of the rocker bridge. A control valve for switching/connecting a hydraulic port to a pressurized oil feed means and an oil pan in response to the driving state of the engine is provided. An oil passage is formed at a position where an angle formed by a linear line tightening an axis of the oil passage and an axis of a guide hole against a linear line tightening axes of two valve stems is within a range of 30-90°. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve mechanism that facilitates raising and lowering of a rocker bridge.
[0002]
[Prior art]
Opening the exhaust valve in the middle of the expansion stroke to reduce the expansion force applied to the piston to improve the effectiveness of the engine brake, or opening the exhaust valve in the middle of the suction stroke An internal EGR in which a part of the exhaust remaining in an exhaust port is returned to a cylinder by controlling a combustion temperature by temporarily opening the valve is well known.
[0003]
In order to open and close the exhaust valve in this manner, Japanese Patent Application Laid-Open No. Hei 9-112234 discloses a valve mechanism for controlling the up / down driving of the rocker bridge, in addition to a cam for driving the rocker bridge up and down, and an operating state of the engine. The valve opening characteristic of the valve can be changed in accordance with the operating state of the engine only by controlling the opening and closing of the control valve by providing a control valve for switching and connecting the hydraulic port to the pressure oil supply means and the oil pan according to A mechanism is disclosed.
[0004]
An example of such a conventional engine valve mechanism will be described with reference to FIG. First, as shown in FIG. 3, a guide pin 2 erected on a cylinder head 1 is inserted into a guide hole 3b provided in a leg 3a of a rocker bridge 3 so as to be able to move up and down. Further, an oil chamber 7 is formed on the upper surface of the piston 6 with the lower surface of the piston 6 fitted to the distal end of the arm 3c of the rocker bridge 3 so as to be able to move up and down so as to face the upper end surface of the stem 4a of the exhaust valve 4. A hydraulic port 8 connected to the pressure oil supply means is provided on the peripheral surface of the guide pin 2, and a control port 9 provided on the inner peripheral surface of the guide hole 3 b so as to face the hydraulic port 8 at the rising position of the rocker bridge 3. , And is connected to the oil chamber 7 via an oil passage 21 provided in the rocker bridge.
[0005]
However, in such a conventional valve mechanism of the engine, a portion provided inside the leg portion 3 a of the oil passage 21 formed in the rocker bridge 3 is provided between the exhaust valve 4 and the guide pin 2. The leg 3a is provided so as to pass through the inside of the leg 3a, and the portion of the leg 3a located on the arm 3c direction side has a large thickness. Therefore, the interval between the two exhaust valves 4, that is, the valve pitch, must be widened structurally, so that the degree of freedom of design is narrowed, and there is a problem that the optimum valve pitch required from engine performance cannot be realized. .
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and has as its main object to provide a bubble mechanism capable of achieving an optimum valve pitch.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a valve mechanism for an engine which opens and closes a valve via a rocker bridge attached to a cylinder head so as to be able to move up and down. A rocker arm contact portion is formed on the upper end surface of the rocker bridge, with which the lower surface of one end of the rocker arm contacts, and the rocker arm contact portion is fitted into the cylinder portion formed on the rocker bridge upper surface side so as to be movable up and down. The piston is supported on the upper surface, an oil chamber is formed on the lower surface of the piston, and a stopper for determining the uppermost position and the lowermost position of the piston is provided inside the cylinder portion. A guide pin erected on the cylinder head is inserted into a guide hole provided in a leg of the rocker bridge so as to be able to move up and down. A hydraulic port connected to the pressure oil supply means is provided on the peripheral surface of the guide pin, and a control port provided on the inner peripheral surface of the guide hole so as to face the hydraulic port at the raised position of the rocker bridge. A control valve for connecting the hydraulic port to the hydraulic oil supply means and the oil pan in response to an operation state of the engine, and a lower end of both ends of the arm of the rocker bridge. Are arranged so that the upper end surfaces of the stems of the valve are opposed to each other, and the oil passage in the leg of the rocker bridge is configured such that the oil passage of the oil passage with respect to a straight line connecting the axes of the stems of the two valves. A valve mechanism is provided, wherein an acute angle formed by a straight line connecting the shaft and the axis of the guide hole is in a range of 30 ° to 90 °.
[0008]
In the present invention, by providing an oil path connecting the control port and the hydraulic port to the oil chamber within the above-described range, an oil path is provided inside the leg portion between the guide pin and the valve. Since it is not provided, the thickness of the leg in that portion can be reduced. As a result, it is structurally possible to provide the valve on the inner side in the arm direction as compared with the conventional art, and the interval between the two valves, that is, the degree of freedom of the valve pitch is increased, and the optimum valve pitch required from the engine performance can be realized. It becomes possible.
[0009]
According to the present invention, there is further provided a valve mechanism for an engine in which a valve is driven to open and close via a rocker bridge attached to a cylinder head so as to be movable up and down. An oil chamber is formed on the upper surface of the piston with the lower surface of the piston facing the upper end surface of the valve stem, and a guide pin erected on the cylinder head is attached to the leg of the rocker bridge. A hydraulic port connected to the pressure oil supply means is provided on the peripheral surface of the guide pin, and the guide hole is provided so as to face the hydraulic port at the raised position of the rocker bridge. A control port provided on the inner peripheral surface of the oil chamber is connected to the oil chamber via an oil passage, and a hydraulic port is provided in response to an operation state of the engine. A control valve for switching connection between the pressure oil supply means and the oil pan is provided, and the oil passage in the leg of the rocker bridge is connected to the axis of the oil passage with respect to a straight line connecting the stems of the two valves. Provided is a valve mechanism, wherein an acute angle of an angle formed by a straight line connecting the guide hole and the axis is in a range of 30 ° to 90 °.
[0010]
As described above, a case where the oil chamber is formed on the upper surface of the piston by attaching the lower surface of the piston to the upper end surface of the valve stem so that the lower surface of the piston is opposed to the upper end surface of the valve stem at both ends of the two arms of the rocker bridge. Similarly, since the oil passage provided in the leg portion is provided within the above-described range, the degree of freedom of the valve pitch is increased, and the optimum valve pitch required from the viewpoint of engine performance can be realized. .
[0011]
According to the second aspect of the present invention, as described in the third aspect, the rocker bridge has a height variation between the left and right valves when the rocker bridge moves up and down to open and close the valve. Height adjusting means for adjusting the height of the cylinder is provided in any one of the cylinders, and the height adjusting means is fitted to the cylinder and the piston is mounted inside the cylinder so as to be movable up and down. And adjusting and fixing means for adjusting and fixing the cylinder portion fitting means to a predetermined height, wherein the cylinder portion fitting means or the cylinder portion has the most It is preferable that a stopper for determining the upper end position and the lowermost position be provided.
[0012]
By providing height direction adjusting means for adjusting the difference in height between the left and right valves caused by the dimensional difference between parts and the dimensional difference generated when the rocker bridge is incorporated in the cylinder head, etc. Can be adjusted to the same height. This makes it possible to drive the rocker bridge up and down satisfactorily, and to easily open and close the valve via the valve. Furthermore, when the piston is driven up and down, by providing an upper stopper and a lower stopper that determine the uppermost position and the lowermost position, the stroke of the left and right pistons controlled by the hydraulic pressure and the spring, etc. , And can be adjusted to a desired stroke.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the valve mechanism of the engine of the present invention will be specifically described with reference to the drawings.
[0014]
FIG. 1 is a schematic sectional view showing one embodiment of a valve mechanism according to the present invention. FIG. 2 is a sectional view taken along line XX shown in FIG.
[0015]
First, as shown in FIG. 1, a guide pin 2 is erected on the upper surface of a cylinder head 1 of an engine, and the guide pin 2 is inserted into a guide hole 3b provided in a leg 3a of a rocker bridge 3 so as to be movable up and down. The bridge 3 is attached to the cylinder head 1 so as to be able to move up and down. A poppet-type exhaust valve 4 is attached to each of the opposing positions with the guide pin 2 interposed therebetween, and the tip of an arm 3c extending left and right from the upper end of the leg 3a faces the extension of the stem 4a of the exhaust valve 4. ing.
[0016]
Further, in the present embodiment, the rocker arm contact portion 12, which is a portion to which the lower surface of one end of the rocker arm 15 of the rocker bridge 3 abuts, can move up and down inside the cylinder portion 5 formed on the upper surface side of the rocker bridge 3. It is formed on the upper surface of the fitted piston 6. Accordingly, the rocker arm contact portion 12 moves up and down in response to the swing of the rocker arm 15, and the piston 6 is driven to move up and down in conjunction with this. An oil chamber 7 is formed on the lower surface of the piston 6. The oil chamber 7 is connected to the control port 9 and the hydraulic port 8 via an oil passage 21 provided in the leg 3 a of the rocker bridge 3.
[0017]
In this embodiment, as shown in FIG. 2, the oil passage 21 has an axis of the oil passage 21 at right angles to a straight line a connecting the axes of the stems 4 a of the two exhaust valves 4. The oil passage 21 is formed so as to be located.
[0018]
Although FIG. 1 shows the oil passage 21 for convenience so as to pass through the inside of the leg 3a between the guide pin 2 and the exhaust valve 4, in the present embodiment, actually, in FIG. Is provided so as to pass through the inside of the leg 3a on the near side or the back side with respect to the paper surface of FIG.
[0019]
With respect to a straight line connecting the axis of the stem of the two exhaust valves and the straight line connecting the axis of the oil passage and the axis of the guide hole, the angle on the acute side is specifically, as shown in FIG. Is in the range of 30 ° to 90 °, and among them, the angle of c is preferably in the range of 45 ° to 90 °.
[0020]
By providing the oil passage within the above range, the thickness of the arm 3c direction side can be reduced in the shape of the leg in which the oil passage is formed, so that the space below the arm is widened structurally. Can be secured. This makes it possible to provide the exhaust valve closer to the inside in the arm direction than before. Therefore, the interval between the two exhaust valves, that is, the degree of freedom of the valve pitch is increased, and the optimum valve pitch required in terms of engine performance can be realized.
[0021]
The embodiment shown in FIG. 1 is an example in which the rocker arm contact portion 12 is supported on the upper surface of the piston 6 inside one cylinder portion 5 provided on the upper surface of the rocker bridge 3, but the present invention is not limited to this. If necessary, a plurality of cylinders may be formed on the upper surface of the rocker bridge, and the rocker arm contact portion is supported by a plurality of pistons inside the plurality of cylinders. It may be.
[0022]
Further, in the cylinder portion 5 in which the piston 6 is fitted to be able to move up and down, an upper stopper 11a and a lower stopper 11b are provided for determining the uppermost position and the lowermost position when the piston 6 is driven up and down. ing. By providing the upper stopper 11a and the lower stopper 11b in this manner, a stroke that has been conventionally determined by the hydraulic pressure, the spring force, and the like can be defined by these stoppers, and can be a desired stroke.
[0023]
There is no particular limitation on the upper stopper 11a and the lower stopper 11b that regulate the stroke of the piston 6 as long as the piston 6 can prevent the piston 6 from moving up and down out of a desired stroke range. Specifically, when a convex portion is provided so as to protrude radially inward of the cylinder portion 5, or when an upper or lower side wall of the cylinder portion 5 is formed so as to protrude radially inward of the cylinder portion 5, Further, a case where a washer having an inner diameter of an opening portion smaller than the inner diameter of the piston 6 may be provided.
[0024]
Further, in this embodiment, in order to adjust the height of both the exhaust valves 4 attached to the tip of the arm 3c, at least one of the arms 3c has a height-direction adjusting means 10 for adjusting the height. May be provided. The height direction adjusting means 10 is not particularly limited as long as it can move the exhaust valve 4 up and down and can fix the exhaust valve 4 at a desired position. Specifically, the lower end surface of the adjusting screw 10a incorporated from the upper surface to the lower surface of the one arm 3c is connected to the upper end surface of the stem 4a of the exhaust valve 4, and by moving the adjusting screw 10a up and down. The height of one exhaust valve 4 is adjusted to the height of the exhaust valve 4 connected to the lower surface of the adjusting screw 10a, and the nut 10b is fixed at a position where the heights of both the exhaust valves 4 are the same. Means for fixing the adjusting screw 10a to the arm 3c using a tool.
[0025]
Further, in this embodiment, since the cylinder portion 5 is provided on the upper surface side of the rocker bridge 3, the stem 4a of the exhaust valve 4 can be directly connected to the lower surface of the distal end of the arm 3c of the rocker bridge 3, The structure can be simplified. Therefore, it is easy to incorporate the adjusting screw, for example, the adjusting screw 10a, into the arm 3c when attaching the height direction adjusting means 10 to the arm 3c. Further, since no oil passage is formed inside the arm 3c, no oil leaks from a through hole or the like in which the adjusting screw 10a is incorporated, and there is little possibility that a decrease in oil pressure occurs.
[0026]
Further, a hydraulic port 8 is provided on the peripheral surface near the upper end of the guide pin 2, and the control port 9 facing the hydraulic port 8 when the rocker bridge 3 is held at the upper end position is connected to the inner peripheral surface of the guide hole 3b. Is provided. By connecting the control port 9 and the oil chamber 7 via an oil passage 21 provided in the leg 3a of the rocker bridge 3, the hydraulic port 8 is connected to the control port when the rocker bridge 3 is held at the upper end position. The oil chamber 7 is connected to the oil chamber 7 through the oil passage 9 and the oil passage 21.
[0027]
A hydraulic pump 20 driven by the operation of the engine is provided as pressure oil supply means, and a pump port 13 a of the control valve 13 is connected to a discharge port of the hydraulic pump 20. The control valve 13 has an open port 13b and an output port 13c in addition to the pump port 13a. The open port 13b is opened to the oil pan 14 of the engine, and the output port 13c is connected to the hydraulic port 8 via an oil passage 22 provided in the guide pin 2. The control valve 13 switches the hydraulic port 8 between the discharge port of the hydraulic pump 20 and the oil pan 14 according to a command from a controller (not shown).
[0028]
The lower surface of one end of the rocker arm 15 disposed above the rocker bridge 3 is in contact with the rocker arm contact portion 12. A cam 16 is brought into contact with the tip of the other end of the rocker arm 15 via a roller 15a. When the cam 16 is driven to rotate with the operation of the engine, the rocker arm 15 in contact with the lower surface of one end of the rocker arm 15 is contacted. The piston 6 is driven up and down in conjunction with the contact portion 12, and the exhaust valve 4 is opened by pushing down the stem 4a through the up and down driving of the piston 6.
[0029]
The cam 16 has a nose 16a for generating a lift amount. The exhaust valve 4 is opened by the nose 16a via the rocker arm 15, the rocker bridge 3, the piston 6, and the like in a conventionally known exhaust stroke. Reference numeral 15b denotes a rocker shaft, reference numeral 17 denotes a suction filter, reference numeral 18 denotes a check valve connected in parallel to the control valve 13, reference numeral 19 denotes an air breather, and a relief (not shown) provided inside the hydraulic pump 20 or in an oil passage on the hydraulic pump 20 side from the control valve. The provision of the valve prevents the hydraulic pressure supplied to the pump port 13a of the control valve 13 from exceeding a predetermined value.
[0030]
In the engine valve mechanism having the above configuration, when the hydraulic pump 20 is driven in accordance with the operation of the engine, oil in the oil pan 14 is discharged from the hydraulic pump 20 and supplied to the pump port 13a of the control valve 13. . When the engine is operating in a normal state, the pump port 13a of the control valve 13 is closed, and the output port 13c is connected to the open port 13b. Therefore, the oil discharged from the hydraulic pump 20 is supplied to the hydraulic port 8 through the check valve 18, but the output port 13 c of the control valve 13 is connected to the open port 13 b, so that the oil is discharged from the hydraulic pump 20. The discharged oil is returned to the oil pan 14 through the check valve 18, and the pressure in the oil chamber 7 is almost equal to the atmospheric pressure.
[0031]
In this state, when the cam 16 rotates to swing the rocker arm 15 counterclockwise in FIG. 1, the piston 6 is pushed down in conjunction with the rocker arm contact portion 12. Then, the rocker bridge 3 descends together with the piston 6 to push down the stem 4a, but the rocker bridge 3 is about to be held at the ascending position by the urging force of the exhaust valve 4.
[0032]
Therefore, before the piston 6 contacts the lower stopper 11b, the oil in the oil chamber 7 flows back from the oil passage 21 provided in the leg 3a to the control port 9 and the hydraulic port 8 as the piston 6 descends, Since the oil flows out from the oil passage 22 provided in the oil pan 2 through the control valve 13 to the oil pan 14, the rocker bridge 3 relatively rises. Therefore, the exhaust valve 4 is kept in the closed state.
[0033]
When the rocking angle of the rocker arm 15 increases and the piston 6 comes into contact with the lower stopper 11b, the rocker bridge 3 descends integrally with the piston 6, so that the stem 4a is pushed down as the rocker bridge 3 descends. The exhaust valve 4 is opened.
[0034]
However, when the control valve 13 is closed by an instruction from a controller (not shown) and the output port 13c is connected to the pump port 13a, the discharge pressure of the hydraulic pump 20 is supplied to the hydraulic port 8 during operation of the engine. Is held. Therefore, in this case, since the oil does not flow out from the control port 9, the oil chamber 7 becomes oil-tight before the piston 6 comes into contact with the lower stopper 11b, and the rocker bridge 3 moves the stem 4a from the beginning of the lowering of the piston 6. As a result, the exhaust valve 4 is driven to open according to the profile of the cam 16.
[0035]
Next, another embodiment of the present invention will be described. FIG. 3 is a schematic sectional view of a valve mechanism showing an example of another embodiment of the present invention. In this embodiment, as shown in FIG. 3, a guide pin 2 is erected on the upper surface of a cylinder head 1 of an engine, and the guide pin 2 is movable up and down in a guide hole 3b provided in a leg 3a of a rocker bridge 3. The rocker bridge 3 is inserted into the cylinder head 1 so as to be vertically movable. A poppet-type exhaust valve 4 is attached to each of the opposing positions with the guide pin 2 interposed therebetween, and the tip of an arm 3c extending left and right from the upper end of the leg 3a faces the extension of the stem 4a of the exhaust valve 4. ing.
[0036]
A hydraulic port 8 is provided on the peripheral surface near the upper end of the guide pin 2, while a control port 9 facing the hydraulic port 8 is provided on the inner peripheral surface of the guide hole 3b when the rocker bridge 3 is held at the upper end position. ing. By connecting the control port 9 and the oil chamber 7 via an oil passage 21 provided in the rocker bridge 3, the hydraulic port 8 is connected to the control port 9 and the oil passage when the rocker bridge 3 is held at the upper end position. The connection is made to the oil chamber 7 via 21.
[0037]
In the present embodiment, the oil passage 21 provided inside the leg 3a is connected to the two exhaust valves 4 as shown in FIG. 2 in the same manner as the embodiment shown in FIG. The oil passage 21 is formed such that the axis of the oil passage 21 is located on the side perpendicular to the straight line a connecting the stem 4a.
[0038]
In FIG. 3, similarly to FIG. 1, the oil passage 21 provided inside the leg 3 a is shown for convenience so as to pass through the inside of the leg 3 a at a portion sandwiched between the guide pin 2 and the exhaust valve 4. However, in the present embodiment, in actuality, it is provided so as to pass through the inside of the leg 3a on the near side or the back side with respect to the sheet of FIG.
[0039]
Also in this embodiment, the oil passage 21 provided inside the leg 3a is formed in the above-described portion, similarly to the embodiment in which the above-described cylinder portion 5 is provided on the upper surface side of the rocker bridge 3. Thereby, a similar effect can be obtained. That is, since the thickness of the leg 3a on the side of the arm 3c can be reduced, a large space under the arm 3c can be ensured structurally. Can be provided. Therefore, it is possible to cope with a valve pitch required from the viewpoint of engine performance in a wide range, and an optimum valve pitch can be realized.
[0040]
With respect to a straight line connecting the axes of the stems of the two exhaust valves with respect to a straight line connecting the axis of the oil passage provided inside the leg and the axis of the guide hole, the angle on the acute side is defined as Since this is the same as the above-described embodiment, the description here is omitted.
[0041]
In this embodiment, a height direction adjusting means 10 is provided in one cylinder portion 5. Such height direction adjusting means 10 has, as adjustment and fixing means, an adjusting screw 10a penetrating from the upper surface of the arm 3c to the oil chamber 7, and a nut 10b for fixing the adjusting screw 10a to the upper surface of the arm 3c. are doing. Further, as the cylinder part fitting means, there is an outer cylinder 10c connected to the tip end of the adjusting screw 10a on the oil chamber 7 side and fitted in the cylinder part 5a. On the inner peripheral surface of the outer cylinder 10c, an upper stopper 11a for determining the uppermost end position when the piston 6 moves up and down is provided. On the other hand, the cylinder portion 5 not provided with the height direction adjusting means 10 is provided. Also, an upper stopper 11a for determining the uppermost position of the piston 6 is provided.
[0042]
In such a height direction adjusting means 10, since the adjusting screw 10a moves up and down and the outer cylinder 10c also moves up and down, the height of the left and right upper stoppers 11a can be adjusted to the same height. As a result, variations in height when the left and right pistons 6 are at the uppermost position can be eliminated.
[0043]
Further, as shown in FIG. 3, a lower stopper 11b for determining the lowermost position of the piston 6 is provided in order to keep the stroke when the left and right pistons 6 are driven up and down. The lower stopper 11b on the side where the height direction adjusting means 10 is provided is provided below the outer cylinder 10c of the height direction adjusting means 10, and the other lower stopper 11b is provided below the cylinder part 5. Has been.
[0044]
In the engine valve mechanism of this embodiment, when the hydraulic pump 20 is driven in accordance with the operation of the engine, the oil in the oil pan 14 is discharged from the hydraulic pump 20 and supplied to the pump port 13a of the control valve 13. Is done. When the engine is operating in a normal state, the pump port 13a of the control valve 13 is closed, and the output port 13c is connected to the open port 13b. Therefore, the oil discharged from the hydraulic pump 20 is supplied to the hydraulic port 8 through the check valve 18, but the output port 13 c of the control valve 13 is connected to the open port 13 b, so that the oil is discharged from the hydraulic pump 20. The discharged oil is returned to the oil pan 14 through the check valve 18, and the pressure in the oil chamber 7 is almost equal to the atmospheric pressure.
[0045]
In this state, when the cam 16 rotates to swing the rocker arm 15 counterclockwise in FIG. 3, the rocker bridge 3 is pushed down. Then, the piston 6 moves down together with the rocker bridge 3 to try to push down the stem 4a, but the piston 6 is about to be held at the raised position by the urging force of the exhaust valve 4.
[0046]
Therefore, before the piston 6 comes into contact with the upper stopper 11a, the piston 6 relatively rises with the lowering of the rocker bridge 3, and the oil in the oil chamber 7 flows backward from the oil passage 21 to the control port 9 and the hydraulic port 8. I do. Then, since the oil flows from the oil passage 22 provided in the guide pin 2 to the oil pan 14 through the control valve 13, the exhaust valve 4 is held in a closed state.
[0047]
When the rocking angle of the rocker arm 15 increases and the descending stroke of the rocker bridge 3 increases, the piston 6 comes into contact with the upper stopper 11 a and descends integrally with the rocker bridge 3. The stem 4a is pushed down and the exhaust valve 4 is opened.
[0048]
However, when the control valve 13 is closed by an instruction from a controller (not shown) and the output port 13c is connected to the pump port 13a, the discharge pressure of the hydraulic pump 20 is supplied to the hydraulic port 8 during operation of the engine. Is held. Therefore, in this case, since oil does not flow out of the control port 9, the oil chamber 7 becomes oil-tight before the piston 6 comes into contact with the upper stopper 11a, and the piston 6 moves the stem 4a from the beginning of the lowering of the rocker bridge 3. As a result, the exhaust valve 4 is driven to open according to the profile of the cam 16.
[0049]
Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention, and any device having the same operation and effect can be realized by the present invention. It is included in the technical scope of the invention.
[0050]
For example, in the above-described embodiment, the present invention is applied to the valve mechanism for opening and closing the exhaust valve 4. However, the present invention is applied to the valve mechanism of the intake valve, and the opening timing of the intake valve is controlled in response to the operating state of the engine. Can be optimally controlled. Further, in the above embodiment, the hydraulic oil supply means is constituted by a hydraulic pump. However, the hydraulic oil supply means may be constituted by an oil pump provided in an engine.
[0051]
【The invention's effect】
According to the present invention, by providing the oil passage connecting the control port and the hydraulic port to the oil chamber in the above-described range, the oil passage is formed inside the leg portion of the portion sandwiched between the guide pin and the valve. Since it is not provided, the thickness of the leg portion at that portion can be reduced. As a result, it is structurally possible to provide the valve on the inner side in the arm direction as compared with the conventional art, and the interval between the two valves, that is, the degree of freedom of the valve pitch is increased, and the optimum valve pitch required from the engine performance can be realized. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a valve mechanism of the present invention.
FIG. 2 is a sectional view taken along line XX shown in FIG.
FIG. 3 is a schematic longitudinal sectional view showing another example of the valve mechanism according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Guide pin 3 ... Rocker bridge 3a ... Leg part 3b ... Guide hole 3c ... Arm 4 ... Exhaust valve 4a ... Stem 5 ... Cylinder part 6 ... Piston 7 ... Oil chamber 8 ... Hydraulic port 9 ... Control port 11a ... upper stopper 11b ... lower stopper 12 ... rocker arm contact part 13 ... control valve 14 ... oil pan 15 ... rocker arm

Claims (3)

In an engine valve mechanism that opens and closes a valve via a rocker bridge attached to the cylinder head so as to be able to move up and down,
A rocker arm contact portion is formed at the upper end surface of the rocker bridge, with which the lower surface of one end of the rocker arm abuts. It is supported on the upper surface of the combined piston, an oil chamber is formed on the lower surface of the piston, and a stopper for determining the uppermost position and the lowermost position of the piston is provided inside the cylinder portion. Yes,
A guide pin erected on the cylinder head is inserted into a guide hole provided on a leg portion of the rocker bridge so as to be able to move up and down. A control port provided on the inner peripheral surface of the guide hole to face the hydraulic port at the raised position of the rocker bridge is connected to the oil chamber via an oil passage, and in response to an operating state of the engine. A control valve for switching connection of the hydraulic port to the pressure oil supply means and the oil pan is provided,
The lower end of both ends of the arm of the rocker bridge is disposed so that the upper end surface of the stem of the valve faces,
The oil passage in the leg of the rocker bridge has an acute angle of an angle formed by a straight line connecting the axis of the oil passage and the axis of the guide hole with respect to a straight line connecting the axes of the stems of the two valves. A valve mechanism formed at a position within a range of 30 ° to 90 °. In an engine valve mechanism that opens and closes a valve via a rocker bridge attached to the cylinder head so as to be able to move up and down,
An oil chamber is formed on the upper surface of the piston, with the lower surface of the piston opposed to the upper end surface of the valve stem and attached to both ends of the two arms of the rocker bridge so as to be movable up and down,
A guide pin erected on the cylinder head is vertically inserted into a guide hole provided in a leg of the rocker bridge, and a hydraulic port connected to pressure oil supply means is provided on a peripheral surface of the guide pin. At the raised position of the rocker bridge, a control port provided on the inner peripheral surface of the guide hole so as to face the hydraulic port is connected to the oil chamber via an oil passage, and the hydraulic port is pressurized in response to an operation state of the engine. A control valve for switching connection between the oil supply means and the oil pan is provided,
The oil passage in the leg portion of the rocker bridge has an acute angle of an angle formed by a straight line connecting the axis of the oil passage and the axis of the guide hole with respect to a straight line connecting the stems of the two valves. Is formed at a position within a range of 30 ° to 90 °. In the rocker bridge, height direction adjusting means for adjusting the variation in the height of the left and right valves when the rocker bridge moves up and down to open and close the valve is provided in any one of the cylinder units, Height direction adjusting means, a cylinder part fitting means fitted into the cylinder part and the piston is mounted therein so as to be vertically movable, and an adjustment fixing means for adjusting and fixing the cylinder part fitting means to a predetermined height And having
The stopper according to claim 2, wherein the cylinder portion fitting means or the cylinder portion is provided with a stopper for determining an uppermost position and a lowermost position when the piston is driven up and down. The described valve mechanism.

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