JPH0893427A - Valve system for engine - Google Patents

Abstract

PURPOSE: To constantly conform the stroke of a gas supply and exhaust valve with the stroke based on a cam profile in a valve system for engines which transmits or does not transmit the force of each cam to the gas supply and exhaust valve while using two or more cams having different cam profiles one another. CONSTITUTION: A valve system for engines has bodies 21, 24, 25 interlocked with a base cam 12 and also interlocked with a stem 14 and a slider 30 interlocked with a working angle changing cam 13 and the relative movements of the bodies 21, 24, 25 and the slider 30 are allowed or limited by installing a plate 32 which can move in the direction at right angles to a shaft center of the stem 14 in a circular groove 302 formed in the slider 30 in the way the plate 32 can comes in and out the groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating system for an engine, and is applicable to a variable valve timing for changing the opening / closing timing of intake / exhaust valves, a variable lift for varying the lift amount of intake / exhaust valves, and the like. .

[0002]

2. Description of the Related Art Heretofore, as a valve operating system of this type of engine, one disclosed in, for example, Japanese Patent Application Laid-Open No. 3-260344 has been known. This is an intake / exhaust valve that opens and closes an intake hole or an exhaust hole that opens in the engine combustion chamber, a valve stem connected to the intake / exhaust valve, and a valve spring that urges the valve stem in a direction to close the intake / exhaust valve. , A cam supported by the cam shaft, and a lifter arranged between the cam and the valve stem. Here, the lifter is arranged in the cylinder head so as to be slidable in the axial direction of the intake / exhaust valve and has an upper end that abuts on the cam, a cylinder body fixed to the cylinder head, and a slide body in the cylinder body. A valve side piston whose lower end abuts on the valve stem and a valve side piston are slidably arranged in the cylinder so as to form a working oil chamber, and the upper end of the piston contacts the body. The cam-side piston is in contact with the spring and the spring biases the cam-side piston toward the body.

The above-mentioned device switches the transmission or non-transmission of the force of the cam to the intake / exhaust valve by supplying the hydraulic pressure to the hydraulic oil chamber and changing the hydraulic pressure. That is,
When the hydraulic oil chamber is at a high pressure (above a predetermined value), the hydraulic pressure in the hydraulic oil chamber acts as a rigid body, so the cam force is
It is transmitted to the valve stem through the cam side piston, the hydraulic pressure in the hydraulic oil chamber, and the valve side piston, and the intake and exhaust valves are opened and closed. When the hydraulic oil chamber becomes low pressure (below a specified value) in this state, the cam force is not transmitted from the cam side piston to the valve side piston, and as a result, the intake / exhaust valve is driven to close and remains closed. It

By the way, in the above-mentioned device, the closing timing of the intake / exhaust valve can be controlled by switching the hydraulic pressure in the hydraulic oil chamber from high pressure to low pressure when the intake / exhaust valve is opened.

[0005]

However, in the above-mentioned lifter, the hydraulic oil chamber to which hydraulic pressure is supplied is formed between the cam side piston and the valve side piston, and the hydraulic pressure in the hydraulic oil chamber is transferred from the cam side piston to the valve side. Since it is a mechanism for transmitting the force to the piston, the stroke of the intake / exhaust valve becomes smaller than the stroke based on the cam profile due to the influence of minute air inevitably present in the hydraulic oil chamber. In other words, it is difficult to match the stroke of the intake / exhaust valve with the stroke based on the cam profile.

Further, since the amount of air in the hydraulic oil chamber fluctuates due to repeated switching of the hydraulic pressure in the hydraulic oil chamber,
The stroke of the intake / exhaust valve may change depending on the amount of air in the hydraulic oil chamber. As a result, in the lifter described above, it is difficult to always match the stroke of the intake / exhaust valve with the optimum stroke (for example, the stroke that maximizes the engine output).

Therefore, the present invention provides a valve operating system for an engine in which two or more cams having different cam profiles are used to transmit or not transmit the force of each cam to the intake and exhaust valves. It is a technical task to always match the stroke based on the cam profile.

[0008]

The technical means (hereinafter referred to as technical means) taken in the invention of claim 1 in order to solve the above-mentioned technical problem is an intake hole or exhaust opening in a combustion chamber of an engine. An intake / exhaust valve that opens and closes a hole and connects to the stem, a first spring that biases the stem in a direction to close the intake / exhaust valve, and a first cam and a first cam that are supported around the cam shaft and have different cam profiles. 2 cams,
A lifter disposed between the cam and the stem, the lifter being slidably disposed in a hole formed in the cylinder head of the engine in the axial direction of the intake / exhaust valve; And a body that abuts the stem, a slider that is slidable in the axial direction of the intake / exhaust valve in the body and is movable relative to the body, and a slider that abuts the second cam. A second spring biased toward the body, a body hole formed in the body and having an axis perpendicular to the axis of the stem, a movable member guide groove formed in the slider so as to overlap with the body hole, and a body. A movable member that is slidably disposed in the hole and is urged by a hydraulic pressure applied to one end to one of a first position that enters the movable member guide groove and a second position that leaves the movable member guide groove. Member and movable member in the direction to oppose hydraulic pressure While energized is that the hydraulic pressure at one end of the movable member is constituted by a third spring to maintain the movable member to the other one of the positions of the first and second position when not in action.

Therefore, in the above technical means, it is possible to adjust at least one of the opening start timing (hereinafter referred to as the open timing) and the closing timing (hereinafter referred to as the close timing) of the intake / exhaust valve. The first cam is composed of a first base circle and a first protruding portion that projects from the first base circle in the radial direction; and the second cam has the same center and the same diameter as the first base circle. Second
A distance between two points of the base circle, the second base circle, and the projecting line of the first projecting portion projecting toward the tip of the first projecting portion, and the distance between each point on the line and the center of the second base circle. Comprises a second projecting portion which is smaller than the distance between the center of the first base circle and the tip of the first projecting portion, and the second projecting portion projects from at least one of the two contact points as a starting point. It is preferable to have at least one bulge portion that bulges outward from the line.

Here, the bulging portion means the distance from the center of the second base circle of each point on the line to the center of the first base circle of each point on the protruding line corresponding to the point. Means a portion larger than the distance.

(A) In order to set the opening timing to an earlier timing, the bulging portion is provided at a portion which comes into contact with the slider first in accordance with the rotation of the second cam among the two forming portions of the bulging portion. .

(B) In order to set the closing timing to a later timing, the bulging portion is provided at a portion which comes into contact with the slider later as the second cam rotates among the two forming portions of the bulging portion.

Further, in the above technical means, it is preferable that two bulging portions are provided and each of the bulging portions is bulged from both contacts in order to adjust both the opening timing and the closing timing of the intake and exhaust valves.

In the above technical means, the first cam is a low lift cam and the second cam has a base circle whose base circle diameter is the first cam in order to change the lift amount of the intake and exhaust valves in two stages. It is preferable that the slider has a high lift cam smaller than the diameter, and the slider always projects toward the second cam side with respect to the body when the movable member exists at the first position where the movable member enters the movable member guide groove.

In order to shorten the axial length of the valve stop mechanism,
It is preferable that the movable member is a plate-shaped member.

In order to ensure that the plate-shaped member can enter the movable member guide groove even when the body and the slider rotate relative to each other, the movable member guide groove formed in the slider is provided in the plate-shaped member. An annular groove having an opening width substantially the same as the thickness is preferable.

[0017]

The operation of the above technical means will be described.

When the movable member is located at the first position where it enters the movable member guide groove formed in the slider due to the action of one of the hydraulic pressure and the third spring, the slider and the movable member engage with each other. The pressing force of the two cams is transmitted from the slider to the stem via the movable member and the body. As a result, the stem, that is, the intake / exhaust valve is moved against the biasing force of the first spring by the pressing force of the second cam,
It opens and closes based on the cam profile.

On the other hand, when the movable member is in the second position where it is disengaged from the movable member guide groove by the action of the hydraulic pressure and the other of the springs, the slider and the movable member are disengaged from each other. The pressing force is not transmitted from the slider to the stem via the body, and the pressing force of the first cam is transmitted to the stem via the body. As a result, the stem, that is, the intake / exhaust valve is moved against the biasing force of the first spring by the pressing force of only the first cam, and is opened / closed based on the profile of the first cam.

As described above, according to the above technical means, it is possible to switch between the opening / closing operation of the intake / exhaust valve based on the profile of the first cam and the opening / closing operation of the intake / exhaust valve based on the profile of the second cam. Is.

According to the above technical means, the slider is provided with the movable member entry groove, and the movable member movable in the direction orthogonal to the axial direction of the intake / exhaust valve can be engaged with the groove. As described above, when the movable member is in the first position where the movable member enters the movable member entrance groove, the force of the second cam is reliably transmitted from the slider to the stem via the movable member and the body. That is, since the hydraulic pressure in the hydraulic oil chamber is not used as a force transmission mechanism, the movable member is
When in the position, the stroke of the intake / exhaust valve can always match the stroke based on the profile of the second cam. Needless to say, even when the movable member is in the second position, the stroke of the intake / exhaust valve can always match the stroke based on the profile of the first cam.

Next, the first and second of the above technical means
The operation when the cam is configured as in claim 2 will be described.

A) When it is desired to set the opening timing to a timing earlier than the normal timing At this time, the movable member is caused to enter the movable member guide groove by the action of one of the hydraulic pressure and the third spring, and is regulated to the first position. To do. In this state, when the first and second cams rotate from the state where the first and second base circles are in contact with the slider, before the protrusion of the first cam starts to engage with the body, The bulge begins to engage the slider. As a result, the pressing force by the bulging portion of the second cam is transmitted from the slider to the stem via the movable member and the body, and the intake / exhaust valve opens based on the profile of the bulging portion of the second cam.
In this way, since the bulging portion of the second cam begins to engage with the slider before the protruding portion of the first cam begins to engage with the body, compared to the case where only the first cam is used (normal) The timing can be set early.

When the rotation of the first and second cams further progresses, the second
The engagement of the bulging portion of the cam with the slider is released, and the protrusion of the first cam starts to engage with the body. As a result, the pressing force by the protruding portion of the first cam is transmitted from the body to the stem, and the intake / exhaust valve opens based on the profile of the protruding portion of the first cam.

(B) When it is desired to set the closing timing to a timing later than the normal timing: As shown in (a) above, the rotation of the first and second cams is further changed from the state in which the protruding portion of the first cam is engaged with the body. As the arrow advances, the bulging portion of the second cam starts to engage with the slider. As a result, the pressing force by the bulging portion of the second cam is transmitted from the slider to the stem via the movable member and the body, and the intake / exhaust valve gradually closes based on the profile of the bulging portion of the second cam. As a result, the closing timing can be set later than when the first cam alone is used (normal).

C) When it is desired to set the opening timing and the closing timing to the normal timing At this time, the movable member is removed from the movable member guide groove and restricted to the second position by the action of the hydraulic pressure and the other of the springs. The pressing force of the bulging portion of the second cam is not transmitted from the slider to the stem via the body, but the pressing force of the first cam is transmitted to the stem via the body. As a result, the intake / exhaust valve is opened / closed based on the profile of the first cam by the pressing force of only the first cam. In this way, since no force is transmitted from the bulging portion to the intake / exhaust valve, the opening / closing timing of the intake / exhaust valve can be set to a normal timing.

As described above in (a) to (b), according to the configuration of claim 2, at least the opening timing and the closing timing of the intake and exhaust valve are changed by changing the shape of the bulging portion of the second cam. It is possible to adjust one timing.

If two bulges are provided, the opening / closing timing of the intake / exhaust valve can be adjusted by changing the shape of the bulges.

Next, the first and second of the above technical means
The operation when the cam is configured as in claim 4 will be described.

When the movable member exists at the first position where the movable member has entered the movable member guide groove due to the action of one of the hydraulic pressure and the third spring, the slider and the movable member engage with each other, so that the pressing force of the high lift cam is increased. It is transmitted from the slider to the stem via the movable member and the body. As a result, the intake / exhaust valve moves against the biasing force of the first spring due to the pressing force of the high lift cam, and opens / closes based on the profile of the high lift cam.

On the other hand, when the movable member is in the second position where it is disengaged from the movable member guide groove due to the action of the hydraulic pressure and the other of the springs, the slider is disengaged from the movable member, so that the high lift cam is pushed. The pressure is not transmitted from the slider to the stem via the body, and the pressing force of the low lift cam is transmitted to the stem via the body. As a result, the intake / exhaust valve moves against the biasing force of the first spring due to the pressing force of the low lift cam, and opens / closes based on the profile of the low lift cam.

Thus, according to the structure of claim 4, the first cam is a low lift cam, the second cam is a high lift cam whose base circle diameter is smaller than the base circle diameter of the first cam, and the movable member is When it is at the first position where it enters the movable member guide groove, the slider is always protruded toward the second cam side from the body, so that the lift amount of the intake / exhaust valve can be changed in two stages.

In the above technical means, when the movable member is a plate-shaped member, the thickness of the movable member becomes thin, so that the axial length of the valve stopping mechanism can be shortened accordingly.

If the slider is cylindrical, the body and the slider can rotate relative to each other. In that case,
When the movable member guide groove is an annular groove, the plate member can surely enter the movable member guide groove even if the body and the slider rotate relative to each other. Further, when the opening width of the movable member guide groove is set to be substantially the same as the thickness of the plate member, it is possible to prevent the plate member from rattling when the plate member enters the movable member guide groove.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

The engine valve operating system according to the first embodiment will be described with reference to FIGS.

The engine valve operating system 10 shown in FIG. 1 includes two base cams (first cams) 12 and 12 (though only one is shown in FIG. 1) supported by a cam shaft 11 and having different cam profiles. One working angle changing cam (second cam) 13 and an intake hole or an exhaust hole (Fig. 2) opened in the engine combustion chamber (not shown) by being attached to and detached from the seat surface 17 formed on the cylinder head 16 of the engine. Intake / exhaust valve 14 for opening and closing (not shown), valve stem (stem) 15 connected to intake / exhaust valve 14, and valve stem 15
Retainer 19 fixed on the outer periphery of the cotter 18 via a cotter 18.
A valve spring (first spring) 20 that engages the valve stem 15 in a direction to close the intake / exhaust valve 14, and a lifter disposed between the cams 12 and 13 and the valve stem 15. 1 and 1. The valve stem 15 is made of a heat resistant material (heat resistant steel, for example).

Here, as shown in FIG. 2, the base cam 1
2 and 12 are arranged adjacent to both sides of a single working angle changing cam 13, and the width of the base cam 12 is approximately half the width of the working angle changing cam 13.

The base cam 12 has a first base circle 121 having a center O coinciding with the axis of the camshaft 11, and a first base circle 121.
It is composed of two starting points C and D on the base circle 121 and a first protrusion 122 that protrudes in the radial direction of the first base circle 121. The first protrusion 122 has a mountain shape that becomes thinner toward the tip.

The working angle changing cam 13 has the first base circle 12
1, a second base circle 131 having the same center O as that of 1 and the same diameter as the first base circle 121, and a protrusion line 1 of the first protrusion 122.
23 two starting points (that is, two contact points by the second base circle 131 and the projecting line 123 of the first projecting portion 122) C,
The second protrusion 132 protrudes from D toward the tip of the first protrusion 122. Here, in the second protrusion 132, the distance between each point on the line and the center of the second base circle 131 is smaller than the distance between the center O of the first base circle 121 and the tip of the first protrusion 122. Has become.

The second projecting portion 132 has two bulging portions 133 and 133 which bulge outward from the projecting line 123 starting from the points C and D and end points E of the two bulging portions 133 and 133. , F is connected to the flat portion 134.
The distance from the center O of the bulging portion 133 gradually increases from the start points C and D toward the end points E and F, and the distance from the center O of each point on the line is at a position corresponding thereto. It is larger than the distance from the center O of each point on the protruding line 123. The distance from the center O of the flat portion 134 gradually decreases from the end points E and F toward the midpoint G thereof. Incidentally, 134 does not have to be limited to the flat portion, and may be curved.

In FIG. 1, as the working angle changing cam 13 rotates in the direction of the arrow from the state where the second base circle 131 is in contact with the lifter 1, the portion that engages with the lifter 1 first (point C, Between E) and the portion (points F,
Although the bulging portion 133 is provided in both portions (between D), the bulging portion 133 is not limited to this and may be provided in only one of them.

Here, in the base cam 12, the tangent line 1 at a certain point H in the projecting line 123 of the base cam 12 located between the points E and F is at the end point E of the bulging portion 133 and in the projecting line 123. The tangent line m at the point I is the bulge 13
It is designed in a shape that passes through the end points F of 3 respectively. As a result, when the point E on the line of the working angle changing cam 13 is engaged with the lifter 1, the protruding line 1 of the base cam 12
23 is engaged with the lifter 1, and when the point I on the protruding line 123 of the base cam 12 is engaged with the lifter 1, the point F on the line of the working angle changing cam 13 is engaged with the lifter 1. Will meet. Therefore, the force transmission between the base cam 12 and the working angle changing cam 13 can be smoothly switched to the lifter 1, and the rattling noise can be prevented as much as possible.

In the lifter 1, a substantially cylindrical outer body 21 is slidably disposed in a cylinder hole 16a formed in the cylinder head 16 of the engine so as to extend in the axial direction of the intake / exhaust valve 14. As shown in FIG. 3, the upper surface 21 a of the outer body 21 is engaged with the base cam 12. Further, the outer body 21 is formed with a cutout portion 21b in order to prevent interference with the working angle changing cam 13. The clearance between the first base circle 121 of the base cam 12 (or the second base circle 131 of the working angle changing cam 13) and the lifter 1 is adjusted by an inner shim 22 fixed to the tip of the valve stem 15. .

In the inner space 23 of the outer body 21,
Two vertically divided inner bodies 24 and 25 are disposed so as to be movable integrally with the outer body 21, and the lower inner body 25 is provided with an inner shim 22 through which the valve stem 1 is inserted.
5 is engaged. The lower inner body 25 is formed with a first slider guide hole 26 having an axial center coinciding with the axial center of the valve stem 15, and the upper inner body 24 also has an axial center coinciding with the axial center of the valve stem 15. A second slider guide hole 27 having a diameter slightly larger than the diameter of the slider guide hole 26 is formed.
Also having a shaft center that coincides with the shaft center of the valve stem 15
A slider guide hole 28 is formed. A body hole 29 having an axis perpendicular to the axis of the valve stem 15 is formed between the inner bodies 24 and 25, and intersects the first slider guide hole 26 as shown in FIG.
The outer body 21 and the inner body 24,
25 constitutes the body of the present invention. Further, both the inner bodies 24 and 25 described above may be integrally formed, or the outer body 21 and both inner bodies 24 and 25 may be integrally formed.

The first, second and third slider guide holes 26,
A slider 30 is movably arranged in each of 27 and 28, and an upper surface 301 thereof is engaged with the working angle changing cam 13.

The slider 30 has a lower inner body 25.
Is urged toward the working angle changing cam 13 side by a spring (second spring) 31 provided between the spring and the bottom surface. The biasing force of the spring 31 is set to be smaller than the biasing force of the valve spring 20.

The slider 30 has a substantially cylindrical shape, and has the above-mentioned cam engaging surface 301, an annular groove (movable member guide groove) 302, a lower first protruding piece 303, and a second central portion.
It is composed of a protruding piece 304 and a third protruding piece 305 located on the upper side and having a diameter larger than the diameter of the first and second protruding pieces 303, 304. The annular groove 302 is opened in the radial direction of the slider 30, and can overlap the body hole 29 and has an opening width substantially the same as the axial width of the body hole 29. First protrusion 3
03 is guided by the first slider guide hole 26, and the third projecting piece 305 is guided by the third slider guide hole 28.
Guided by. The slider 30 is made of a wear resistant material (for example, carburized material).

The slider 3 is provided in the body hole 29 described above.
A plate 32 having substantially the same thickness as the opening width of the annular groove 302 of 0, that is, the axial width of the intake / exhaust valve of the body hole 29 is slidably guided. The plate 32 has an intake / exhaust valve 1
4, a through hole 33 penetrating in the axial direction is formed, and the diameter of the through hole 33 is equal to the diameter of the first and second projecting pieces 303 of the slider 30.
It is approximately the same as the outer diameter of 304. The plate 32
A semicircular cutout 34 is formed on the left end face of the.
The plate 32 itself enters the annular groove 302 formed in the slider 30 (that is, the body hole 29 and the annular groove 3).
02) (first position (state shown in FIGS. 1 and 4)) to a second position (state shown in FIGS. 5 and 6) in which the device itself leaves the annular groove 302. Here, when the plate 32 is in the first position, as shown in FIG.
Since the axial center of the through hole 33 is deviated from the axial center of the slider 30, the slider 30 is attached to the inner body 24, 25.
It is impossible to move relative to. Meanwhile, plate 3
When 2 is in the second position, as shown in FIG. 6, the axis of the through hole 33 coincides with the axis of the slider 30, so that the slider 30 can move relative to the inner bodies 24 and 25.

The plate 32 is made of a wear resistant material (for example, carburized material).

A hydraulic chamber 35 is formed between the left end of the plate 32 and the outer body 21, and the hydraulic pressure in the oil pan 36 is controlled by a hydraulic pump 37, an electromagnetic switching valve 38, a hydraulic passage 39 formed in the cylinder head, and the outer body 21. It is adapted to be supplied through an annular groove 40 and a passage 41 formed in the. The electromagnetic switching valve 38 is electrically connected to a controller (not shown) into which the operating state of the engine such as the engine speed and the engine load is input, and the state of FIG. The state can be switched to state 5. The plate 32 can be moved from the second position shown in FIGS. 5 and 6 to the first position shown in FIGS. 1 and 4 by the hydraulic pressure acting on the hydraulic chamber 35. still,
The hydraulic pressure in the hydraulic chamber 35 is changed to the passage 41, the groove 40, the hydraulic passage 39.
Also, the oil can be discharged to the oil pan 36 via the electromagnetic switching valve 38.

On the other hand, a spring chamber 42 is formed between the right end of the plate 32 and the outer body 21. A spring (third spring) 43 is arranged in the spring chamber 42, and urges the plate 32 in a direction that opposes the hydraulic pressure, that is, in a direction that reduces the volume of the hydraulic chamber 35. Here, the urging force of the spring 43 is set to be smaller than the force of the hydraulic pressure, and when the hydraulic pressure is not acting in the hydraulic chamber 35, the urging force of the spring 43 causes the plate 32 to move to the positions shown in FIGS. It is maintained in the second position shown. An oil drain hole 44 is formed in the lower inner body 25 so as to open to the spring chamber 42, so that a small amount of oil entering the spring chamber 42 from the hydraulic chamber 35 can be discharged to the outside of the lifter 1. ing.

The plate 32 may be biased from the first position to the second position by hydraulic pressure and the plate 32 may be biased to the second position by the spring 43.

The operation of the valve operating system 10 of the engine according to the first embodiment constructed as described above will be described.

When the engine is started, the camshaft 11
Starts to rotate, and as a result, both cams 12 and 13 are rotationally driven. First, when it is desired to set the opening timing of the intake / exhaust valve 14 earlier than usual and the closing timing of the intake / exhaust valve 14 later than usual, the electromagnetic switching valve 40 is switched to the state of FIG. 1 by the controller. Then, the hydraulic pump 3
7, the oil pressure in the oil pan 36 is changed to the hydraulic passage 39, the groove 4
It is supplied to the hydraulic chamber 35 via 0 and the passage 41. As a result, the plate 32 moves from the second position toward the first position against the biasing force of the spring 43, and a part of the plate 32 enters the annular groove 302 of the slider 30 (that is, the plate 32 is a body hole). 29 and the annular groove 302), so that the plate 32 is stopped in the first position by the bottom surface of the annular groove 302 as shown in FIG. This prevents relative movement between the slider 30 and the plate 32, that is, the outer body 21 and the inner bodies 24, 25.

In this state, when the rotation proceeds from the state where both cams 12 and 13 are in contact with the lifter 1 at the base circles 121 and 131, before the first protrusion 122 of the base cam 12 starts to engage with the outer body 21. The bulging portion 133 of the working angle changing cam 13 starts to engage with the slider 30. As a result, the pressing force of the bulging portion 133 is transmitted from the slider 30 to the valve stem 15 via the plate 32 and the lower inner body 25, and the intake / exhaust valve 14 separates from the valve seat 17 and is based on the bulging portion 133. Open only the profile. That is, while the bulging portion 133 is engaged with the slider 30, as shown in FIG.
Opens based on the profile of the bulge 133. As described above, since the bulging portion 133 of the working angle changing cam 13 starts to engage with the slider 30 before the first protruding portion 122 of the base cam 12 begins to engage with the outer body 21, when using only the base cam 12 The opening timing of the intake / exhaust valve 14 can be set earlier than in (normal).

As the rotation of both cams 12 and 13 progresses further, the engagement between the bulging portion 133 and the slider 30 is released (that is, the working angle changing cam 13 engages with the slider 30 at the point E). The first protrusion 122 of the base cam 12 starts to engage with the outer body 21 (that is, the base cam 12 engages with the outer body 21 at the point H). As a result, the pressing force of the base cam 12 is transmitted from the outer body 21 to the valve stem 15 via the upper inner body 24, the plate 32 and the lower inner body 25, and the intake / exhaust valve 1
4 opens according to the profile of the base cam 12.
That is, as shown in FIG. 7B, the lift of the intake / exhaust valve 14 is switched from that based on the profile of the bulging portion 133 of the working angle changing cam 13 to that based on the profile of the base cam 12.

When the rotation of both cams 12 and 13 progresses further from the state where the base cam 12 is engaged with the outer body 21, the engagement between the base cam 12 and the outer body 21 is released (that is, the base cam 12 is at point I). Outer body 2
1) and the other bulge 133 of the working angle changing cam 13 starts to engage with the slider 30 (that is, the working angle changing cam 13 engages with the slider 30 at the point F). As a result, the pressing force of the bulging portion 133 is transmitted from the slider 30 to the valve stem 15 via the plate 32 and the lower inner body 25, and the valve stem 15 is closed according to the profile based on the bulging portion 133. That is, the bulging portion 13
While 3 is engaged with the slider 30, (c) in FIG.
As shown in, the intake / exhaust valve 14 is closed based on the profile of the bulging portion 133. As a result, the closing timing of the intake / exhaust valve 14 can be set to a later timing than usual.

Although the outer body 21 and the slider 30 may rotate during the above operation, the base cam 12 is always engaged with the cam engaging surface 21a of the donut-shaped outer body 21 and the working angle changing cam 13 is provided. Is always engaged with the cam engagement surface 301 of the circular slider 30, and the area of the engagement area of the cam surface at that time is always constant, which causes no problem in operation.

Next, when it is desired to set the opening timing and the closing timing of the intake / exhaust valve 14 to normal, the controller switches the electromagnetic switching valve 38 to the state shown in FIG. Then, the hydraulic pressure in the hydraulic chamber 35 is discharged to the oil pan 36 via the passage 41, the groove 40, and the hydraulic passage 39. As a result, the urging force of the spring 42 causes the plate 32 to move to the first position.
From the position toward the second position, part of the plate 32 is released from the annular groove 302, and the axis of the through hole 33 of the plate 32 coincides with the axis of the valve stem 15, that is, the slider 30, as shown in FIG. It stops at the second position. This enables relative movement between the slider 32 and the plate 34, that is, the outer body 21 and the inner bodies 24, 25.

Therefore, the cams 12 and 13 are formed on the base circle 12
1,131, the rotation progresses from the state in which the lifter 1 is in contact with the lifter 1, and the bulging portion 133 of the working angle changing cam 13 causes the slider 30 to move.
Even when the valve stem 1 is engaged with the valve stem 1, the pressing force by the bulging portion 133 is applied from the slider 30 via the lower inner body 25.
5, the pressing force of the base cam 12 is transmitted to the valve stem 15 via the outer body 21, the upper inner body 24, the plate 32, and the lower inner body 25. As a result, the intake / exhaust valve 14 opens and closes based on the profile of the base cam 12. Thus, the bulge 133
Since no force is transmitted from the intake / exhaust valve 14 to the intake / exhaust valve 14,
The opening / closing timing of 4 can be set to a normal time.

Next, a valve operating system for an engine according to the second embodiment will be described with reference to FIGS. 8 and 9.

The engine valve operating system 10 according to the second embodiment.
Is basically similar to that of the first embodiment,
Only the points different from the first embodiment will be described. Note that, in FIG. 8, the same reference numerals are given to those having substantially the same structure as the first embodiment.

As shown in FIG. 8, a low lift cam 12a and a high lift cam 13a are employed, an outer body 21 is engaged with the low lift cam 12a, and a slider 30a is engaged with the high lift cam 13a. Here, the width of the third protrusion 305a of the slider 30a in the axial direction of the intake / exhaust valve 14 is larger than the width of the first and second protrusions 303, 304, and the upper surface thereof, that is, the cam engaging surface 301a is the outer body 2.
The upper surface of the No. 1, that is, the cam engaging surface 21a, protrudes toward the high lift cam side (upward in the drawing). Also, the low lift cam 12a
Two high lift cams 13a (not shown) are arranged adjacent to each other on both sides.

The low lift cam 12a is the first base circle 12
1a and a first projecting portion 122a projecting from the first base circle 121a in the radial direction thereof. The high lift cam 13a has a second center having the same center as that of the first base circle 121a and a diameter smaller than that of the first base circle 121a.
It is composed of a base circle 131a and a second protrusion 132a protruding from the second base circle 131a in the same direction as the protrusion direction of the first protrusion 122a. Here, the length between the tip of the second protrusion 132a and the center of the base circle is set so that the high lift cam 13a has a higher lift than the low lift cam 12a. It is set to be larger than the length between.

The operation of the valve operating system 100 for an engine according to the second embodiment constructed as described above will be briefly described.

First, when the plate 32 exists in the first position where it has entered the annular groove 302 by the action of hydraulic pressure, the slider 30a and the plate 32 engage with each other, so that both cams 1
As the 2a and 13a rotate, the pressing force of the high lift cam 13a is transmitted from the slider 30a to the valve stem 15 via the plate 32 and the lower inner body 25.
As a result, the intake / exhaust valve 14 moves against the urging force of the valve spring 20 due to the pressing force of the high lift cam 13a, and FIG.
As indicated by the solid line in FIG.
Open and close based on your profile.

Next, when the hydraulic pressure is released, the spring 43
By this action, the plate 32 moves to the second position where it is disengaged from the annular groove 302, and the engagement between the slider 30 and the plate 32 is released. Then, the pressing force of the high lift cam 13 a is not transmitted from the slider 30 to the valve stem 15 via the lower inner body 25, and the low lift cam 12 a
The pressing force of the outer body 21, the upper inner body 24,
It is transmitted to the valve stem 15 via the plate 32 and the lower inner body 25. As a result, the low lift cam 12
Due to the pressing force of the intake / exhaust valve 14, the intake / exhaust valve 14 moves against the urging force of the valve spring 15, and as shown by the dotted line in FIG.
4 opens and closes based on the profile of the low lift cam 12a.

[0069]

The invention of claim 1 has the following effects.

Since the movable member entry groove is formed in the slider and the movable member which moves in the direction orthogonal to the axial direction of the intake / exhaust valve can be engaged with the groove, the movable member enters the movable member entry groove. When in the first position, the force of the second cam is reliably transmitted from the slider to the stem via the movable member and the body. That is, since the hydraulic pressure in the hydraulic oil chamber is not used as a force transmission mechanism, the stroke of the intake / exhaust valve should always match the stroke based on the profile of the second cam when the movable member is in the first position. You can Even when the movable member is at the second position,
It goes without saying that the stroke of the intake / exhaust valve can always match the stroke based on the profile of the first cam. As described above, the stroke of the intake / exhaust valve can always be maintained at the optimum stroke.

The invention of claim 2 has the following effects.

The opening timing or the closing timing of the intake / exhaust valve can be adjusted by changing the shape of the bulging portion of the second cam.

The invention of claim 3 has the following effects.

Since the two bulging portions are provided, the opening / closing timing of the intake / exhaust valve can be adjusted by changing the shapes of the bulging portions.

The invention of claim 4 has the following effects.

The first cam is a low lift cam, the second cam is a high lift cam whose base circle diameter is smaller than the base circle diameter of the first cam, and the movable member exists at the first position where the movable member enters the movable member guide groove. At times, the slider is always projected toward the second cam side with respect to the body, so the lift amount of the intake / exhaust valve can be changed in two stages.

The invention of claim 5 has the following effects.

Since the movable member is a plate-shaped member, the thickness of the movable member is thin, and the axial length of the valve stopping mechanism can be shortened accordingly.

The invention of claim 6 has the following effects.

Since the movable member guide groove is annular, the plate member can surely enter the movable member guide groove even if the body and the slider rotate relative to each other. Furthermore, since the opening width of the movable member guide groove is set to be substantially the same as the thickness of the plate member,
It is possible to prevent the plate-shaped member from rattling when the plate-shaped member enters the movable member guide groove.

[Brief description of drawings]

FIG. 1 is a diagram showing a valve operating system for an engine (hydraulic O
It is sectional drawing of (at the time of N).

FIG. 2 is a side view of the cam shown in FIG.

FIG. 3 is a plan view of the lifter in FIG.

4 is a cross-sectional view taken along the line AA in FIG.

FIG. 5 is a diagram showing a valve operating system for an engine (hydraulic O
FIG.

6 is a sectional view taken along line BB in FIG.

FIG. 7 is an operating characteristic diagram (a time chart of lift amounts of intake and exhaust valves) of the valve operating system for the engine according to the first embodiment.

FIG. 8 is a valve operating system for an engine according to the second embodiment (hydraulic O
It is sectional drawing of (at the time of N).

FIG. 9 is an operating characteristic diagram (time chart of lift amount of intake and exhaust valves) of the valve operating system for the engine according to the second embodiment.

[Explanation of symbols]

 1, 2 Lifter 10, 100 Engine Valve Operating Device 11 Cam Shaft 12 Base Cam (First Cam) 121 First Base Circle 122 First Projection 123 Protrusion Line 12a Low Lift Cam (First Cam) 13 Working Angle Change Cam (First 2 cam) 131 2nd base circle 132 2nd protrusion part 133 bulging part 13a high lift cam (2nd cam) 14 intake / exhaust valve 15 valve stem (stem) 16 cylinder head 16a cylinder hole (hole) 20 valve spring (first) Spring) 21 Outer body (body) 24, 25 Inner body (body) 29 Body hole 30, 30a Slider 301, 301a Slider cam engaging surface 302 Annular groove (movable member guide groove) 31 Spring (second spring) 32 Plate (movable) Material) 43 Spring (3rd spring)

Claims (6)

[Claims] 1. An intake / exhaust valve that opens and closes an intake hole or an exhaust hole that opens in a combustion chamber of an engine and is connected to a stem, and a first spring that urges the stem in a direction to close the intake / exhaust valve. A first cam and a second cam, which are supported around a cam shaft and have different cam profiles, and a lifter arranged between the cam and the stem, wherein the lifter is inside a cylinder head of an engine. A body that is slidable in the axial direction of the intake / exhaust valve in a hole formed in the body and that abuts the first cam and the stem, and slides in the body in the axial direction of the intake / exhaust valve. It is arranged so as to be freely movable relative to the body,
A slider that contacts the cam; a second spring that biases the slider toward the second cam; a body hole that is formed in the body and has an axis that is orthogonal to the axis of the stem; A movable member guide groove formed in the slider so as to overlap with the body hole; a first position slidably disposed in the body hole and entering the movable member guide groove by hydraulic pressure acting on one end; A movable member that is urged to any one of the second positions that move out of the movable member guide groove; and a hydraulic pressure that acts on one end of the movable member while urging the movable member in a direction that opposes the hydraulic pressure. And a third spring that maintains the movable member in the other one of the first and second positions when not in operation. 2. The first cam according to claim 1, wherein the first cam has a first base circle and a first protruding portion that protrudes from the first base circle in a radial direction thereof. A second base circle having the same center and the same diameter as the first base circle, and two contact points formed by the second base circle and the projecting line of the first projecting portion project toward the tip of the first projecting portion, and A second protrusion formed by making the distance between each point on the line and the center of the second base circle smaller than the distance between the center of the first base circle and the tip of the first protrusion. An engine valve operating device in which the second protrusion has at least one bulge that bulges outward from the protrusion line starting from at least one of the two contacts. 3. The valve operating system for an engine according to claim 2, wherein the two bulging portions are provided, and each of the bulging portions starts from the both contacts. 4. The movable member according to claim 1, wherein the first cam is a low lift cam, and the second cam is a high lift cam whose base circle diameter is smaller than the base circle diameter of the first cam. The valve operating device for the engine, wherein the slider always projects toward the second cam side with respect to the body when the slider is present at the first position where the slider enters the movable member guide groove. 5. The engine valve operating system according to claim 1, 2, 3, or 4, wherein the movable member is a plate-shaped member. 6. The engine according to claim 1, 2, 3, 4, or 5, wherein the movable member guide groove formed in the slider is an annular groove having an opening width substantially the same as the thickness of the plate member. Valve device.