JPH0874535A - Valve timing variable device - Google Patents

Abstract

PURPOSE: To always realize the engagement of a pin in the regular engaging position when a valve timing is changed in a valve timing variable device for varying the valve timing through a process of connecting a shaft to a fitting member after engaging a pin member capable of projecting from the shaft with a recessed engaging part of the fitting member capable of slid in the peripheral direction of the shaft. CONSTITUTION: A valve timing variable device is provided with a first energizing means for always energizing a pin member 7 in the projecting direction and a second energizing means 9 for energizing the pin member 7 in the projecting direction when a valve timing is changed, and a recessed engaging part 13 of a fitting member 6 is provided with a first groove 13c through which the tip of the pin member 7 smoothly passes the regular engaging position 13b. And a first energizing force to act on the pin member 7 by the first energizing means is not so large to connect a shaft 4 to the fitting member 6, and the sum of a second energizing force to act on the pin member 7 by the second energizing means 9 and the first energizing force is the magnitude wherein the shaft 4 and the fitting member 6 can be connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing variable device for switching valve timing by making it possible to select whether or not to transmit an operation of a cam provided on a cam shaft to an engine valve such as an intake valve or an exhaust valve.

[0002]

2. Description of the Related Art Two types of cams having different profiles, one for low speed and one for high speed, have different profiles in order to improve the output torque of the engine in the high speed range while keeping the low speed and high torque in the low speed range of the engine. Is provided on the camshaft, and there is a valve mechanism that drives the valve with a low speed cam in the low speed rotation range of the engine and with a high speed cam in the high speed rotation range.
More specifically, the mechanism for changing the valve timing is provided on the cam shaft so that the first and second cams having different cam profiles are always in contact with one valve.
Then, by rotatably attaching the first cam to the cam shaft, the valve is driven at the timing of the second cam having a shape different from that of the first cam. On the other hand, by connecting the first cam and the cam shaft with a pin, the valve is driven at a timing according to the shape of the first cam. The valve timing is switched by connecting or disconnecting the cam and the cam shaft with a pin according to the operating state of the engine.

As a method of connecting the camshaft and the first cam with a pin, a hydraulic circuit provided in the camshaft pushes the pin into a concave engagement portion provided in the cam lobe to connect the camshaft and the cam. It is driving. However, since this camshaft constantly rotates at high speed in response to the output from the engine, there is a problem in that the pin is difficult to engage with the concave engagement portion. JP 62-13190
According to Japanese Patent Laid-Open No. 7-74, a spring member for constantly urging the pin into the cam shaft is arranged in the concave engagement portion provided on the cam lobe side, whereby a pin that is pushed into the cam shaft and rotates together with the cam shaft is hydraulically operated. When engaging the concave engaging portion, the pin gradually presses the spring member so that the tip of the pin reaches the regular engaging position of the concave engaging portion in the circumferential direction of the concave engaging portion. It is described that one side is provided with a run-up groove leading to a regular engagement position. With such a structure, in order to change the valve timing, when the hydraulic pressure is applied before the pin moves onto the run-up groove, the tip of the pin is surely engaged at the regular engagement position in the concave engagement portion. Therefore, good engagement between the pin and the concave engagement portion can be achieved.

[0004]

However, in the above-mentioned prior art, when the pin pushed into the camshaft by the spring member is located in the middle of the run-up groove and hydraulic pressure is applied to the pin, the pin is depressed. The pin cannot press the spring member sufficiently in the time until it opposes the regular engagement position of the mating portion, and the tip of the pin reaches the middle of the regular engagement position in the concave engagement portion. Attempts to start the engagement at an odd position to rotate the camshaft. When the cam shaft and the cam rotate in this state, a large force acts on the pin, and as a result, stress concentrates on the pin, causing problems such as deterioration of durability and damage.

Therefore, an object of the present invention is to engage a pin member capable of projecting from the shaft with a concave engaging portion of the fitting member slidable in the circumferential direction of the shaft so that the shaft and the fitting member can be connected to each other. In a variable valve timing device that changes the valve timing by connecting them, when the intention is to connect the shaft and the fitting member, always achieve good engagement between the pin and the concave engagement portion at the regular engagement position. It is possible to prevent the deterioration and damage of the durability of the pin.

[0006]

A valve timing varying device according to a first aspect of the present invention is a pin member capable of protruding from a shaft in a concave engaging portion of a fitting member slidable in the circumferential direction of the shaft. In the valve timing variable device that changes the valve timing by connecting the shaft and the fitting member by engaging the pin, the pin member is projected even when it is not intended to connect the shaft and the fitting member. And a second urging means for urging the pin member in the projecting direction when it is intended to connect the shaft and the fitting member. The concave engagement portion of the member has a regular contact between the first contact position with the shaft of the fitting member and the tip end portion of the pin member on the side where the pin member approaches the concave engagement portion as the shaft moves. Smoothly engages with the engaging position of The first urging force acting on the pin member by the first urging means is an external force acting on the fitting member even when the tip of the pin reaches the engagement position. Is not so large as to couple the shaft and the fitting member against each other, and the sum of the second urging force acting on the pin member by the second urging means and the first urging force is When the tip portion reaches the engagement position, the size is such that the shaft and the fitting member can be coupled against each other against the external force acting on the fitting member.

A valve timing varying device according to a second aspect of the present invention is the valve timing varying device according to the first aspect, wherein the concave engaging portion of the fitting member is
Further, on the side where the pin member moves away from the concave engagement portion with the movement of the shaft, a second engagement between the regular engagement position of the tip end portion of the pin member and the shaft of the fitting member is possible.
A second groove that smoothly connects the contact position,
The groove has a first inclined surface on the engagement position side and a second inclined surface on the second contact position side, and is opposed to the pressing force applied to the second groove by the pin member in accordance with the movement of the shaft. The angle of the first inclined surface is set such that the component force in the direction of pushing the pin member into the shaft is smaller than the sum of the first urging force and the second urging force. Is greater than the sum of the first biasing force and the second biasing force, the angle of the second inclined surface is set.

A valve timing varying device according to a third aspect of the present invention is the valve timing varying device according to the first aspect, wherein the shaft is a cam shaft, the fitting member is a cam, and the concave engagement member is a cam. The joint portion is formed in a portion of the cam opposite to the cam nose portion with respect to the center of the cam shaft.

A valve timing varying device according to a fourth aspect of the present invention is the valve timing varying device according to the first aspect, wherein the shaft has at least two opening / closing valve operations for providing different opening / closing valve operations to the engine valve. When two mating members are arranged and the second biasing means intends to couple the shaft with a selected one of the two mating members, the one mating member is connected to the shaft. It is a selective urging means for urging only the pin member for connecting to.

According to a fifth aspect of the present invention, there is provided a valve timing changing device according to the fourth aspect, wherein the shaft is a rocker arm shaft and the two fitting members are fixed to a cam shaft. It is a follower driven by two different types of cams.

A valve timing varying device according to a sixth aspect of the present invention is the valve timing varying device according to the fourth aspect, wherein the selective biasing means is provided between two set positions in the axial direction of the shaft. A piston member capable of reciprocating motion is provided, and at one set position, one of both end portions of the piston member urges one of the two pin members in the projecting direction by the second urging force, and at the same time, The other pin member is not biased by the recess provided in the central portion of the piston member, and at the other set position, the other of both ends of the other pin member pushes the other of the two pin members in the protruding direction. At the same time as being urged by the urging force, one of the pin members is not urged by the recess provided in the central portion of the piston member.

[0012]

In the variable valve timing device according to the first aspect, the pin member for connecting the shaft and the fitting member is
Even when this coupling is not intended, the first biasing means biases the fitting member in the projecting direction so that the concave engagement portion of the fitting member smoothly moves from the first contact position with the shaft to the regular engagement position of the pin member. Since it has the first groove connected to, the tip portion of the pin member moves along the first groove to reach the regular engagement position. First acting on the pin member by the first biasing means
Since the urging force is relatively small, at this time, the shaft and the fitting member are not joined against each other against the external force acting on the fitting member, but the pin member is provided with the second member to join the fitting member and the shaft. When the biasing force is applied, even if the pin member is located on the first groove at this time, it is not necessary to sharply increase the stroke of the pin member, and the pin member can be securely engaged in the concave shape along the first groove. The regular engagement position of the part is reached.

The variable valve timing device according to claim 2 is the variable valve timing device according to claim 1, wherein the concave engagement portion of the fitting member has a regular engagement position and a shaft of the fitting member. And a second groove for smoothly connecting the second contact position with the second groove, and when only the first biasing force of the first biasing means acts on the pin member, the tip end portion of the pin member has the first and second grooves. Along the smooth passage through the concave engagement portion. The tip of the pin member is the first on the engagement position side of the second groove.
When positioned on the inclined surface, the component force in the direction of retracting the pin member into the shaft in the reaction force against the pressing force acting on the second groove via the pin member along with the movement of the shaft is the first biasing force and the second biasing force. Since the sum of the force is smaller than the sum of the force, when the second biasing force acts on the pin member by the second biasing means at this position, the fitting member slightly advances in the movement direction of the shaft and the tip end portion of the pin member is concave. The engagement member is engaged with the regular engagement position, and the fitting member and the shaft are coupled. Further, when the tip end portion of the pin member comes into contact with the second inclined surface on the second contact position side of the second groove, the aforementioned component force becomes larger than the sum of the first urging force and the second urging force. Even when the second biasing force acts on the pin member by the second biasing means, the pin member is pushed into the shaft, and the tip end portion of the pin member tries to engage with the regular engaging position of the concave engaging portion. It is possible to prevent the fitting member from significantly advancing in the movement direction of the shaft, and to prevent the pin member from engaging at a halfway position of the concave engaging portion.

The valve timing varying device according to claim 3 is the valve timing varying device according to claim 1, wherein the shaft is a cam shaft, the fitting member is a cam, and the concave engagement portion is Since the cam is formed at a portion opposite to the cam nose portion with respect to the center of the cam shaft, a relatively large reaction force when the engine valve is opened by the cam nose portion near the concave engagement portion of the cam. Does not work.

The valve timing varying device according to the fourth aspect is the valve timing varying device according to the first aspect, wherein at least two fittings are provided on the shaft for giving different opening and closing operations to the engine valve. A member is disposed and the second biasing means is provided for coupling one of the mating members to the shaft when it is intended to couple the shaft and the selected one of the two mating members. Since one of the fitting members is coupled with the shaft, the other fitting member is slidable in the circumferential direction of the shaft because it is the selective biasing means for biasing only the pin member. There is no influence on the opening / closing operation of the engine valve by the fitting member, and the opening / closing operation given to the engine valve by the two fitting members can be freely set.

The valve timing varying device according to claim 5 is the valve timing varying device according to claim 4, wherein the shaft is a rocker arm shaft and two fitting members are fixed to the camshaft. Are followers driven by respective cams, and only one follower is coupled to the rocker arm shaft by the selective biasing means.
The rocker arm opens and closes the engine valve by the operation of the corresponding cam.

According to a sixth aspect of the present invention, there is provided a valve timing varying device according to the fourth aspect, wherein the selective biasing means reciprocates between two set positions in the axial direction of the shaft. When the piston member is provided with one of the two end portions of the piston member and one of the two pin members is biased by the second biasing force in the projecting direction, the piston member is provided with one possible setting position. At the same time, the other pin member is not biased by the recess provided in the central portion of the piston member, and by setting the other set position, the other of the two end portions of the piston member causes the other of the two pin members to move to the second position. It is one of two fitting members because it is biased by the biasing force and at the same time, one pin member is not biased by the recess formed in the center of the piston member. It is possible to bind to the axis.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are schematic views of a valve timing varying device according to a first embodiment of the present invention. In these drawings, the valve timing varying device 1 is a valve 2
And a valve lifter 3 attached to the top of the valve 2, a cam shaft 4 for driving the valve lifter 3, primary cams 5, 5 ', and a secondary cam 6. The primary cams 5 and 5'are fixed to the cam shaft 4 and rotate in synchronization with the rotation of the cam shaft 4. On the other hand, the secondary cam 6 and the primary cams 5 and 5 ′ have different cam profile shapes, and are engagement pins that are movable in the radial direction of the cam shaft along the ball moving hole 12 formed in the cam shaft 4. Depending on the position of the ball 7, the cam shaft 4 is switched to be coupled or rotatable with respect to the rotating cam shaft 4. The primary cam 5, 5'or the secondary cam 6 drives the valve lifter 3 by the rotation of the cam shaft 4 and lifts the valve 2.

A piston 9 slidable in a piston hole 11 is provided in the camshaft 4, and the camshaft 4 is rotatably supported by a camshaft bearing (not shown). The oil passage 8 provided in the camshaft 4 and the camshaft bearing
The hydraulic pressure P is supplied to the piston 9 provided in the camshaft 4 through the hydraulic pressure P, and the position of the piston 9 is controlled by the hydraulic pressure P. The concave portion 13 of the secondary cam 6 with which the ball 7 engages has a first contact position 13 a between the secondary cam and the cam shaft and a regular engagement of the ball 7 on the side where the ball 7 approaches the concave portion 13 as the cam shaft 4 rotates. The first groove 13 that smoothly connects the top portion 13b that is the mating position
c and the ball 7 is recessed by the rotation of the camshaft 4.
It has a second groove 13e that smoothly connects the second contact position 13d between the secondary cam and the cam shaft and the regular engagement position 13b of the ball 7 on the side away from the secondary cam.

When the hydraulic pressure P is not supplied to the oil passage 8, the piston 9 is brought into a predetermined engagement / disengagement position (position represented by the piston 9 in FIG. 2) by the spring force of the return spring 10, and the piston 9 Due to the annular recess formed in the center of the ball 7, the urging force in the ball projecting direction due to the hydraulic pressure does not act on the ball 7. On the other hand, when the oil pressure P is supplied to the oil passage 8, the oil is moved to a predetermined engagement position (position represented by the piston 9 in FIG. 1) against the spring force of the return spring 10, and the piston 9
A large urging force in the projecting direction acts on the ball 7 by the end portion of. Further, even when the engagement / disengagement position is reached to the engagement position, the sloping surface of the annular recess applies a biasing force to the ball 7 in the ball protruding direction due to the hydraulic pressure. The oil passage P is ON / OFF controlled according to the operating state of the engine by opening and closing an electromagnetic hydraulic control valve provided in a hydraulic passage connected to an oil pump (not shown) by an electronic control unit. Here, the pin member of claims 1 to 6 corresponds to the ball 7 in this embodiment.

The behaviors of the ball 7, the secondary cam 6, and the cam shaft 4 when the piston 9 is in the engagement / disengagement position are shown in FIGS. 3 (a) to 3 (d).
Since the ball 7 rotates around the center of the cam shaft together with the cam shaft 4, a centrifugal force acts as a first urging force, and at a position facing the recess 13 of the secondary cam 6, as shown in FIG. Then, the regular engagement position 13b is reached along the first groove 13c. However, since this centrifugal force is relatively small, the secondary cam 6
Is against the reaction force acting on the secondary cam 6 by pushing down the valve lifter 3, the connection between the secondary cam 6 and the cam shaft 4 cannot be maintained, and
As shown in (c), the ball 7 is pushed into the camshaft 4, and the camshaft 4 freely rotates with respect to the secondary cam 6.

The behavior when the hydraulic pressure is supplied from the state shown in FIG. 3 to the piston hole 11 through the oil passage 8 is shown in FIGS.
It is shown in (d). Since the centrifugal force acts on the ball 7 as described above, regardless of the time when the hydraulic pressure acts, the ball 7 moves to the concave portion 13 of the secondary cam 6.
If the pressing force of the piston 9 by the hydraulic pressure has already acted on the ball 7 as the second urging force at this time, the pressing force of the secondary cam is considerably large. Against the above-mentioned reaction force acting on the valve 6, the connection between the secondary cam 6 and the cam shaft 4 is maintained, and the valve via the valve lifter 3 by the secondary cam 6 is maintained as shown in FIGS. Driving is started. In this way, since the ball 7 always moves along the concave portion 13 of the secondary cam 6, for example,
When hydraulic pressure acts on the first groove 13c, the pin member is suddenly moved to move to the regular engagement position of the recess 13 as in the conventional case in which the pin member rotates while being pushed into the camshaft. It is not necessary to increase the stroke, and the reliable engagement between the ball 7 and the recess 13 can be realized no matter what time the hydraulic pressure is applied.

The behavior when the secondary cam 6 and the camshaft 4 are coupled in this manner is shown in FIGS.
Shown in Further, the behavior when the supply of the hydraulic pressure to the piston 9 is stopped from this state is shown in FIGS. 6A to 6D, and the reaction force acting on the secondary cam 6 while the valve is closed is extremely small. When it is small, the centrifugal force acting on the ball 7 maintains the coupling between the secondary cam 6 and the camshaft 4, and the cam nose portion of the secondary cam 6 is moved to the valve lifter 3 as shown in FIGS. 6 (a) to 6 (c). The secondary cam 6 rotates together with the cam shaft 4 until just before pushing down, and thereafter, as shown in FIG. 6 (d), the ball 7 is disengaged, and the cam shaft 6 moves relative to the secondary cam 6 as in FIG. Rotate freely.

Next, the ball 7 moving along the concave portion 13 of the secondary cam 6 by the centrifugal force is moved to the second portion of the concave portion 13.
The case where hydraulic pressure acts on the groove 13e will be described in detail. FIG. 7A is a state diagram at this time, and FIG. 7B is an enlarged view of the S portion near the contact portion between the ball 7 and the second groove 13e of the secondary cam 6. Figure 7 (b)
In the second groove 13 e,
Of the secondary cam 6 and the second contact position 13d of the secondary cam 6 with the cam shaft are smoothly connected to each other by a curved surface A having a predetermined radius larger than the ball 7 and an inclined surface B.

The contact point R with the ball 7 in the second groove 13e is pressed by the ball 7 in a direction perpendicular to the direction connecting the contact point R and the center of the camshaft with the rotation of the camshaft 4. The direction of this pressing force and the second groove 13e
Let r be the angle formed by and this angle (hereinafter contact angle)
r is the point P on the second contact position 13d side and the regular engagement position 1
It is different at point Q on the 3b side, and if the contact angle at point P is r ₁ and the contact angle at point Q is r ₂ , then r ₁ <
The relationship of r ₂ is established. In addition, the ball 7 is in the second groove 13
When it is located on the curved surface A of e, its contact angle r is always larger than r ₂ . Figure 8 (a) shows the relationship of force at point P.
Fig. 8 (b) shows the force relationship at point Q. Note that FIG.
In (a) and (b), the ball 7 is shown smaller than it actually is in order to make it easy to see. Here, since the above-mentioned pressing force is associated with the rotation of the cam shaft 4, it is equal regardless of the position of the contact point R of the ball 7 with respect to the second groove 13e, and the predetermined reaction force F is always applied to the ball 7. Works. The predetermined reaction force F is divided into a first component force Fq that vertically pushes the second groove 13e and a second component force Fp that pushes the ball 7 back into the camshaft 4. At this time, if the contact angle r is small, as shown in FIG.
Becomes larger and the contact angle r becomes larger, the second component force Fp becomes smaller as shown in FIG. 8 (b). That is, the contact angle r
Is smaller, the force Fp for pushing back the ball 7 into the camshaft 4 is larger, and the larger the contact angle r is, the smaller is the force Fp for pushing back.

FIG. 8C shows the contact angle r and the inside of the camshaft 4.
The relationship of the force Fp for pushing back the ball 7 is shown. In addition, the above
From the center of the camshaft to the outside due to centrifugal force and hydraulic pressure
The force to push the ball 7 is F₀And based on the R point
How much in the direction of rotation around the shaft
The amount of deviation shown is θ. Here, FIG. 8C shows the same as the engaging portion.
The force Fp that pushes back the ball according to the phase shift θ
Force F₀It shows the relationship with. Watch this
And the phase difference θ in the second groove 13e of the recess 13 is θ>
│θ₂｜ 、 θ ＞ ｜ θ₁When |, Fp> F₀Next day
At this point the ball 7 is pushed back into the camshaft 4.
And the camshaft 4 and the secondary cam 6 are connected.
Instead, the balls 7 will be joined the next time they reach the recess 13.
Also, the phase difference θ is θ₂<Θ <θ₁Then Fp <F₀When
And when θ = 0, F₀-Fp is positive and maximum
Therefore, the secondary cam 6 rotates slightly and the ball
7 is engaged with the regular engagement position 13b, and the camshaft 4 and
The secondary cam 6 will rotate integrally.
Also, when the hydraulic pressure P is not acting, the centrifugal force F alone is applied.
₁, And the ball 7 continues to rotate without being fixed.
It

In the prior art, since such a consideration is not taken into consideration when setting the angle of the second groove, when the hydraulic pressure acts on the pin member at a position where the phase difference θ in the second groove is relatively large, the above-mentioned problem occurs. Fp becomes smaller, and at this position the pin member and the recess engage with each other, resulting in an incomplete connection between the secondary cam and the cam shaft, and the ball 7
May suddenly rotate the secondary cam 6 in an attempt to engage with the regular engagement position of the recess 13 to generate a very large cam (valve motion) acceleration, which may cause an abnormal motion such as a jump of the valve. In the above embodiment, FIG.
As can be seen from the force relationship diagram of Fig. 6, if the angle is shifted by a small angle, it immediately returns to the regular engagement position 13b, and if the timing at which the hydraulic pressure P is applied is delayed even a little, the engagement is postponed once and the engagement is surely engaged in the next cycle. Therefore, the above-mentioned abnormal movement of the valve can be prevented.

FIG. 9 shows a second embodiment of the present invention. As is clear from the comparison with FIG. 7B, the difference from the first embodiment is that the inclined surfaces of the second groove 13e are different from the first and second inclined surfaces B ′ and C ′ having different inclination angles. It is configured. In consideration of the centrifugal force and the hydraulic pressure acting on the ball 7, based on the above-mentioned concept, the first inclined surface B ', when the ball 7 is positioned on the first inclined surface B', keeps the ball 7 even if the hydraulic pressure acts. The angle is set so as to surely push the ball 7 back into the camshaft 4, and the second inclined surface C ′ ensures that the ball 7 is in the regular engagement position when hydraulic pressure acts when the ball 7 is positioned on the second inclined surface C ′. Angled to engage.
Therefore, when the hydraulic pressure acts when the ball 7 is located on the second groove, whether the secondary cam 6 and the cam shaft 4 are coupled depends on the first inclined surface B ′ and the second inclined surface C ′. It is clearly distinguished and the above-mentioned problems during coupling can be reliably prevented.

FIG. 10 shows a third embodiment of the present invention. This is provided with a plurality of balls 7 and recesses 13 of the valve timing varying device of the first embodiment, and the engageable phase is only once per one rotation of the camshaft. By providing a plurality of engaging portions in this way, the rotation restraining force per engaging portion can be reduced, so that the hydraulic pressure acting on the piston can be reduced.

FIG. 11 shows a fourth embodiment of the present invention. This is the variable valve timing device according to claim 3,
It is needless to say that the same effect as that of the first embodiment can be obtained by applying the secondary cam or the primary cam to the cam nose, which is the cam profile portion that drives the valve, as in the embodiment. A concave portion 13 is provided on the side opposite to the camshaft central axis of the portion. As a result, in general, the cam nose is pushed by the urging force toward the cam shaft as a reaction that occurs when the valve is driven. However, by adopting the configuration of the fourth embodiment, the cam and the cam shaft are The contact area can be increased and the surface pressure can be reduced.
The durability of the engaging portion can be improved.

FIGS. 12, 13, 14, and 15 show a fifth embodiment of the present invention. The present embodiment is a case where the present invention is applied to a valve operating mechanism in which a cam drives a valve via a rocker arm. In FIG. 12, reference numeral 20 denotes a rocker arm shaft, to which first and second rocker arms 21a and 21b for simultaneously driving the two engine valves 2 are fixed. First and second followers 22a and 22b are swingably fitted to the rocker arm shaft 20 between the first and second rocker arms 21a and 21b. FIG.
As shown in FIG. 13, which is an exploded perspective view of No. 2, the first and second followers 22 a and 22 b and the hollow rocker arm shaft 20.
Between the first and second balls 23a, 23b similar to the above.
An engagement mechanism is provided that uses the and piston 24. The opening 20 a for inserting the piston 24 into the rocker arm shaft 20 is sealed by the lid member 25. The first and second rocker arms 21a of the rocker arm shaft 20,
Holes 26a and 26b formed on both sides of 21b are oil supply holes for providing hydraulic pressure to both ends of the piston 24 located inside the rocker arm shaft 20.

As shown in FIG. 14, the first and second followers 22a and 22b have first and second cams 28a and 28b having different profiles fixed to the camshaft 27, which are in contact with the upper ends of the tips of the first and second followers 22a and 22b. 1st and 2nd follower 22
a and 22b perform different swinging motions. The valve timing varying device of the present embodiment uses one of the followers 22 using the engagement mechanism similar to that described above.
The valve timing is changed by connecting a or 22b to the rocker arm shaft 20.

FIG. 15 is a partial longitudinal sectional view of the rocker arm shaft 20. As shown in the figure, the rocker arm shaft 2
Both ends of 0 are rotatably supported by bearings 29a and 29b. In the space inside the rocker arm shaft 20, the piston 24 is regulated at both ends by the first stopper 30a formed in this space and the second stopper 30b formed in the above-mentioned lid member, and the above-mentioned oil supply is performed. By supplying the hydraulic oil from one of the holes 26a and 26b, the hydraulic oil is discharged from the other oil supply hole, and the piston 24
Is the first and second as shown in FIGS. 15 (a) and 15 (c).
It is designed to move between predetermined positions. FIG.
(B) shows an intermediate position between the first and second predetermined positions. During such movement of the piston 24, both end portions 24a and 24b of the piston 24 are locked by the rocker arm shaft 20.
It slides in an inner space in an oil-tight manner so that the working oil does not enter the annular recess 24c provided in the central portion of the piston 24.

At the first predetermined position of the piston 24 shown in FIG.
One end 24a of the rocker arm shaft 20 is forcibly pushed out of the rocker arm shaft 20 to engage with the recess of the first follower 22a, and the first follower 22a and the rocker arm shaft 20 are coupled to each other. Due to the provided annular recess 24c, the urging force in the protruding direction does not act on the second ball 23b, and the second follower 22b and the rocker arm shaft 20 are not coupled, so the valve is driven by the operation of the first cam 27a. .

Further, the piston 2 shown in FIG.
4, the second ball 23b is moved by the other end 24b of the piston 24 into the rocker arm shaft 20.
Is forcibly pushed out of the second follower 22b to engage with the recess of the second follower 22b, and the second follower 22b and the rocker arm shaft 20 are coupled to each other, while the annular recess 24c provided in the center of the piston 24 causes the first ball to move. Since the urging force in the protruding direction does not act on 23a and the first follower 22a and the rocker arm shaft 20 are not coupled, the valve is driven by the operation of the second cam 27b. When the piston 24 is being switched from one predetermined position to the other predetermined position,
As shown in FIG. 5 (B), the first and second balls 23a, 23
Since there is a state in which both b are not biased in the protruding direction, both followers are not coupled to the rocker arm shaft 20 simultaneously, even momentarily.

Although not shown in detail, the recesses formed in the first and second followers 22a and 22b have the same shape as that described in the first or second embodiment. When engaging with the second balls 23a and 23b, the first groove can ensure reliable engagement between the ball and the recess regardless of the hydraulic pressure applied at any time. Abnormal movements such as valve jumps due to rapid rotation of the followers are prevented.

As in the first embodiment described above, in the mechanism for changing the valve timing by making the secondary cam connectable or slidable with respect to the cam shaft to which the primary cam is fixed, the cam nose of the primary cam is used. The shape of the part must be chosen so that there is no part projectingly projecting with respect to the shape of the cam nose part of the secondary cam connected to the camshaft. This is because even when the secondary cam is connected to the camshaft, the primary cam rotates with the camshaft, and if the above-mentioned protruding portion exists on the primary cam, this protruding portion causes the secondary cam to open / close the engine valve. This is because it affects the. As described above, the profiles of the primary cam and the secondary cam cannot be freely selected, and for example, the valve timing cannot be changed so as to advance the opening timing and the closing timing of the engine valve at the same time.

However, in the present embodiment, when one of the first and second followers 22a and 22b for giving different opening / closing operations to the engine valve is connected to the rocker arm shaft 20, the other one is different from the rocker arm shaft 20. The two cam profiles fixed to the camshaft can be freely selected without being influenced by each other, and two kinds of valve timing can be set freely. It will be possible.

FIG. 16 shows a sixth embodiment of the present invention. The difference from the fifth embodiment is that an elastic member, such as a spring 31, for biasing the piston 24 toward one predetermined position causes the piston 24 to move. It is provided instead of the hydraulic system that provides the hydraulic pressure for urging in the predetermined position direction. Even with such a structure, the same operation of the piston 24 as described above can be realized, and since the number of hydraulic systems 26 is one, the structure can be simplified as compared with the fifth embodiment.

In the fifth embodiment, if the hydraulic pressure is not applied to both ends of the piston 24, the reaction force at the time of opening the engine valve causes the first and second followers 22a, 22a,
22b freely rotates with respect to the rocker arm shaft 20, and the position of the piston 24 becomes an intermediate position as shown in FIG. 15 (b). At this time, in the structure of the fifth embodiment, the engine valve is kept closed. However, in the fifth embodiment, the camshaft 27 is brought into contact with one of the rocker arms 21a or 21b so that the first and second rocker arms 21a or 21b are contacted.
By adding a third cam whose shape is selected so that there is no projecting portion with respect to the cam nose portions of the cams 28a and 28b, when the piston 24 is in the first predetermined position, the first cam causes the engine valve to move. Is driven, the engine valve is driven by the second cam when the piston 24 is in the second predetermined position, and the engine valve is driven by the third cam when the piston 24 is in the intermediate position. It is possible to change the valve timing. Of course, in the sixth embodiment as well, the piston 2
By controlling the hydraulic pressure so as to have a value equal to the urging force of the elastic member 31 having the intermediate position of 4, the piston 24 can be maintained at the intermediate position, and if a similar third cam is provided on the camshaft. The valve timing can be switched in three steps.

The structure for connecting either of the two followers to the rocker arm shaft shown in the fifth and sixth embodiments is as follows.
Of course, it is also possible to apply to two cams provided so as to be rotatably fitted to the cam shaft. In addition, a single cam or follower that is rotatable or swingable is fitted to the cam shaft or the rocker arm shaft, and the engagement mechanism described in the first and second embodiments is provided, so that the engine valve can be operated during engine operation. It is also possible to intentionally close the valve. If such a variable valve timing mechanism is applied to an intake valve on the straight port side of an internal combustion engine in which the helical port and the straight port communicate with the combustion chamber via the intake valves, respectively The valve can be closed, and intake air can be supplied to the combustion chamber only through the helical port without generating a swirl control valve in the straight port, and a strong swirl can be generated in the combustion chamber.

In all the embodiments described so far,
A ball was used as a member projecting from a shaft for coupling or uncoupling a fitting member such as a cam or a follower to a shaft such as a cam shaft or rocker arm shaft, but this does not limit the present invention. As a modified example of the first embodiment, even if a prismatic member 7'is used instead of a ball as in the seventh embodiment shown in FIG. 17, a centrifugal force acting on the prismatic member 7'as a first biasing force is applied. The prismatic member 7'is
The fitting member 6 ′ moves along the concave engaging portion 13 ′ having the first groove 13c ′ and the second groove 13e ′, and at what point in time, the hydraulic pressure as the second biasing force acts on the prismatic member 7 ′. Even if the prismatic member 7'is set to the regular engaging position 13 of the concave engaging portion 13 '.
It is possible to surely engage the b ′ with the fitting member 6 ′ without causing an abnormally large turning motion. Further, in all the embodiments, the first urging force applied to the pin member such as the ball or the prism member uses the centrifugal force, but of course, an appropriate amount of oil pressure, an elastic force of a spring or rubber, or It is also possible to use a force such as an electromagnetic force, and this is the same as the second biasing force which is hydraulic in the embodiment.

[0043]

As described above, according to the valve timing varying device of the first aspect of the present invention, the pin member for connecting the shaft and the fitting member connects the shaft and the fitting member. Even when not intended, the first biasing means biases the pin member in the projecting direction and smoothly connects the pin member provided in the concave engagement portion of the fitting member to the regular engagement position.
When only a relatively small first biasing force acts on the pin member to move along the groove, the shaft and the fitting member are not coupled against the external force acting on the fitting member, but When the second biasing force is applied, even if the pin member is located on the first groove at this time, the pin member surely moves along the first groove without causing the stroke of the pin member to increase, and the pin engaging member can be surely moved to the regular position. Reaching the engaging position, the pin member engages at a halfway position of the concave engaging portion, a large force acts on the pin member, and the pin member is not damaged or durability is deteriorated. To be prevented.

According to the valve timing variable device of the second aspect, in addition to the effect of the valve timing variable device of the first aspect, the concave engagement portion of the fitting member has its regular engagement. Second between the mating position and the shaft of the fitting member
If the second biasing force acts on the pin member when the pin member has a second groove that smoothly connects to the contact position and the tip end portion of the pin member is located on the first inclined surface on the engagement position side of the second groove. , The component force in the direction of retracting the pin member into the shaft in the reaction force against the pressing force acting on the second groove via the pin member in accordance with the movement of the shaft, is based on the sum of the first urging force and the second urging force at this time. Because of the small size, the fitting member slightly advances in the movement direction of the shaft, the tip end portion of the pin member engages with the regular engagement position of the concave engagement portion, and the fitting member and the shaft are coupled. Further, when the second biasing force acts on the pin member when the tip end portion of the pin member is located on the second inclined surface on the second contact position side of the second groove, the above-mentioned component force is combined with the first biasing force. 2 is larger than the sum of the biasing force, the pin member is pushed into the shaft and rotates together with the shaft, and then engages with the regular engagement position of the concave engagement portion along the first groove. The fitting member and the shaft are coupled. Thereby, when the second biasing force acts when the pin member is located on the second inclined surface of the second groove, the pin member is not pushed into the shaft and is engaged with the concave engagement portion at this position. , A large force acts on the pin member, the pin member is damaged, or the tip of the pin member tries to engage with the regular engagement position of the concave engagement portion, and the fitting member is greatly moved in the axial movement direction. It is possible to prevent the valve from moving abnormally and causing abnormal movement of the valve, such as sudden opening of the valve.

According to the valve timing varying device of the third aspect, in addition to the effect of the valve timing varying device of the first aspect, the shaft is the cam shaft and the fitting member is the cam. Since the concave engagement portion is formed on the cam on the side opposite to the cam nose portion with respect to the center of the cam shaft, a relatively large reaction force acts when the engine valve is opened by the cam nose portion. The contact pressure between the cam and the cam shaft does not increase due to the recess, and the durability of the cam is prevented from being deteriorated.

According to the valve timing varying device of the fourth aspect, in addition to the effect of the valve timing varying device of the first aspect, the shafts of the engine valve can be opened and closed differently from each other. At least two mating members for providing are disposed and the second biasing means couples the one mating member to the shaft when it is intended to couple the shaft and one of the two mating members. Since it is the selective urging means for urging only the pin member, when one fitting member is coupled with the shaft, the other fitting member is slidable in the circumferential direction of the shaft. Therefore, the opening / closing operation given to the engine valve can be freely set by the two fitting members, and the valve timing can be changed so as to accelerate the valve opening and closing timings at the same time.

According to the valve timing varying device of the fifth aspect, in addition to the effect of the valve timing varying device of the fourth aspect, the shaft is the rocker arm shaft and the two fitting members are These followers are respectively driven by two kinds of cams fixed to the camshaft, and only one follower is connected to the rocker arm shaft by the selective biasing means, and the rocker arm opens and closes the engine valve by the operation of the corresponding cam. Therefore, the follower oscillates with respect to the rocker arm shaft when it is disengaged, and the sliding surface is less worn than the cam that rotates with respect to the camshaft, and the durability of the entire device is improved. Can be improved.

According to the valve timing varying device of the sixth aspect, in addition to the effect of the valve timing varying device of the above-mentioned fourth aspect, the selective urging means has two types in the axial direction within the shaft. A piston member capable of reciprocating between set positions is provided, and by setting the piston member to one set position, one of the two end portions of the piston member causes one of the two pin members to be attached second in the projecting direction. At the same time as being urged by the urging force, the other pin member is not urged by the recess formed in the central portion of the piston member, and when the other pin member is set to the other set position, the other pin member has two The other of the pin members is urged by the second urging force, and at the same time, one pin member is not urged by the recess provided in the central portion of the piston member, so that the structure is relatively simple. In it is possible to combine only one of the two fitting members axially.

[Brief description of drawings]

FIG. 1 is a first valve timing varying device according to the present invention.
It is a schematic diagram showing a state where a secondary cam and a cam shaft in an example are combined.

FIG. 2 is a first valve timing varying device according to the present invention.
It is a schematic diagram showing a rotatable state of a secondary cam and a cam shaft in an example.

FIG. 3 is a first valve timing varying device according to the present invention.
FIG. 6 is a behavior diagram in a freely rotatable state in the example.

FIG. 4 is a first valve timing varying device according to the present invention.
FIG. 6 is a behavior diagram when the rotatable state is changed to the coupled state in the example.

FIG. 5 is a first part of a valve timing varying device according to the present invention.
FIG. 7 is a behavior diagram in the coupled state in the example.

FIG. 6 is a first part of a valve timing varying device according to the present invention.
FIG. 6 is a behavior diagram when the coupled state is changed to the rotatable state in the example.

FIG. 7 is a first valve timing varying device according to the present invention.
It is a diagram showing a shape of a concave engaging portion in the embodiment,
(A) is a general view, (b) is an enlarged view of the S portion of (a).

FIG. 8 is a first valve timing varying device according to the present invention.
It is a figure explaining the force relation which acts on the ball located on the 2nd groove in an example, when (a) the contact angle with the 2nd groove of a ball is small, (b) is the contact angle with the 2nd groove of a ball. Is large, (c) is a graph showing the relationship between the contact angle and the force for pushing back the ball.

FIG. 9 is a second valve timing varying device according to the present invention.
It is a figure which shows the shape of the concave engagement part corresponded to FIG. 7 in an Example.

FIG. 10 is a diagram when a ball is engaged in the valve timing varying device according to the third embodiment of the present invention.

FIG. 11 is a diagram when a ball is engaged in the valve timing varying device according to the fourth embodiment of the present invention.

FIG. 12 is a perspective view showing a fifth embodiment of the valve timing varying device according to the present invention.

FIG. 13 is an exploded perspective view of FIG.

FIG. 14 is a side view of FIG.

15 is a longitudinal sectional view of the rocker arm shaft of FIG.

FIG. 16 is a view, corresponding to FIG. 15, showing a sixth embodiment of the valve timing varying device according to the present invention.

FIG. 17 is a view corresponding to FIG. 7 showing a seventh embodiment of the valve timing varying device according to the present invention, (a) is an overall view, and (b) is an enlarged view of a U portion of (a). .

[Explanation of symbols]

 1 ... Valve timing variable device 2 ... Valve 3 ... Valve lifter 4 ... Cam shaft 5,5 '... Primary cam 6 ... Secondary cam 7 ... Ball 8 ... Oil passage 9 ... Piston 10 ... Return spring 11 ... Piston hole 12 ... Ball moving hole 13 ... Recess 20 ... Rocker arm shaft 21a ... 1st rocker arm 21b ... 2nd rocker arm 22a ... 1st follower 22b ... 2nd follower 23a ... 1st ball 24 ... Piston 27 ... Cam shaft 28a ... 1st cam 28b ... 2nd cam 31 ... Elastic member

Claims (6)

[Claims] 1. A valve timing for connecting a shaft and a fitting member by engaging a pin member capable of protruding from the shaft with a concave engaging portion of a fitting member slidable in the circumferential direction of the shaft. In the variable valve timing device for changing the valve, a first urging means for urging the pin member in the protruding direction even when it is not intended to connect the shaft and the fitting member, the shaft and the fitting member. A second urging means for urging the pin member in the projecting direction when the pin member is intended to be coupled with the member, and the concave engaging portion of the fitting member is configured such that the pin member is operative to operate the shaft. Accordingly, on the side closer to the concave engagement portion, a first groove that smoothly connects the first contact position with the shaft of the fitting member and the regular engagement position of the tip end portion of the pin member, It acts on the pin member by the first biasing means. The first biasing force is not so large as to couple the shaft and the fitting member against the external force acting on the fitting member even when the tip portion of the pin reaches the engagement position, 2 The sum of the second urging force acting on the pin member by the urging means and the first urging force opposes the external force acting on the fitting member when the tip of the pin reaches the engagement position. A valve timing varying device having a size such that the shaft and the fitting member can be coupled together. 2. The regular engagement of the tip end portion of the pin member on the side where the pin member moves away from the concave engagement portion due to the movement of the shaft. A second groove for smoothly connecting a position and a second contact position of the fitting member with the shaft, wherein the second groove has a first inclined surface on the engagement position side and a second contact position side. And a second inclined surface of the first slanted surface, the component force in the direction of pushing the pin member into the shaft in the reaction force against the pressing force applied to the second groove by the pin member in accordance with the movement of the shaft, The angle of the first inclined surface is set to be smaller than the sum of the biasing force and the second biasing force, and the component force is larger than the sum of the first biasing force and the second biasing force. The angle of the second inclined surface is set to The variable valve timing device described. 3. The shaft is a cam shaft, the fitting member is a cam, and the concave engagement portion is formed in a portion of the cam opposite to the cam nose portion with respect to the center of the cam shaft. The valve timing varying device according to claim 1, wherein 4. The shaft is provided with at least two fitting members for imparting different on-off valve operations to the engine valve, and the second biasing means includes the shaft and the two fitting members. Selective urging means for urging only the pin member for connecting the one fitting member to the shaft when intending to connect the selected one of the two. Item 1. The valve timing variable device according to Item 1. 5. The valve according to claim 4, wherein the shaft is a rocker arm shaft, and the two fitting members are followers driven by two types of cams fixed to a cam shaft. Timing variable device. 6. The selective biasing means comprises a piston member capable of reciprocating between two set positions in the axial direction within the shaft, and the piston member has one of the two end positions at one set position. At the same time, one urges one of the two pin members in the protruding direction by the second urging force, and at the same time,
The other pin member is not biased by the recess provided in the central portion of the piston member, and at the other set position,
The other of the both ends urges the other of the two pin members in the protruding direction by the second urging force, and at the same time, the one pin member is not urged by the recess provided in the central portion of the piston member. The variable valve timing device according to claim 4, wherein