JPS6062613A - Variable valve mechanism - Google Patents

Abstract

PURPOSE:To prevent the movement of a plunger as well as attain quick changeover of the operating characteristics of a valve by directly moving the plunger by the hydraulic method and, on the contrary, deeply engaging a catching member, or the preventive means for the movement of the plunger, with said plunger to restrict any movement thereof when the valve is lifted. CONSTITUTION:Changeover of the operating characteristics of a valve is attained by axially displacing a cam shaft 1 so that either cam 5 or 6 can rock a rocker arm 9. The displacement of the cam shaft 1 is controlled by a plunger 27 which is disposed inside a fixed member 21 and moved in response to the pressure of oil supplied according to the action of solenoid control valves 50 and 51. Catching holes 42 and 43 are formed in the fixed member 21 and the engagement of a catching member 40 in either the hole 42 or 43 prevents the movement of the plunger 27. The depth at which the catching member 40 is engaged therewith is regulated by a cam 8. When the valve is lifted, the engagement is made deeply to prevent any movement of the plunger 27, hence preventing any evidence of damages on the cam or the rocker arm.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a variable valve mechanism that switches cams for opening and closing intake and exhaust valves in accordance with engine operating conditions.

As is well known in the prior art, internal combustion engines can reduce fuel consumption and greatly improve driving performance by switching the opening/closing timing and lift amount of intake and exhaust valves according to operating conditions. As a means for switching the opening/closing timing and lift amount, it is known to have two types of cams for controlling the opening and closing of the intake and exhaust valves, for example, one for high speed and one for low speed.

Now, conventionally, there is a system in which this cam switching is performed using hydraulic pressure. That is, the piston is slidably fitted into the cylinder, the piston is connected to the cam piece, and hydraulic pressure is introduced into the pressure chambers on both sides of the piston to drive the piston, thereby switching the cam piece. It is something that is driven.

However, this hydraulic drive usually uses a common pump for supplying lubricating oil to the engine, so the response speed of the piston is slow due to the limitation of the discharge flow rate. Therefore, it is necessary to provide a spring to increase the cam movement speed, and a ratchet mechanism to store the movement of the piston in the spring force until the cam piece starts moving. Conventional variable valve mechanisms have a complicated structure. Ta. Furthermore, even if the pump flow rate is increased, there is a certain limit to the piston response speed due to the incompressibility of the oil, making it difficult to achieve rapid switching of the cam piece.

OBJECTS OF THE INVENTION In view of the above points, the present invention has been made with the object of providing a variable valve mechanism that can quickly switch cams and has a simple structure.

Structure of the Invention The device of the present invention comprises: an opening/closing member that contacts an intake/exhaust valve of an internal combustion engine; first and second cams that engage with the opening/closing member to open/close the intake/exhaust valve; and these cams or the opening/closing member. a fixing member provided near the fixing member; a plunger supported by the fixing member in a reciprocating manner and connected to the cam or the opening/closing member; and a locking hole supported by the plunger and formed in the fixing member. a locking member that can be fitted into the
and a biasing mechanism that biases the plunger to move the cam or the opening/closing member to switch the engagement relationship between the cam and the opening/closing member. The fitting depth of the locking member into the locking hole can be changed, and when one of the cams is opening the intake/exhaust valve, the fitting depth is increased to prevent the movement of the cam or the opening/closing member. prevent.

Example The present invention will be explained below with reference to the illustrated embodiments.

In FIGS. 1 and 2, a cam piece 3 is fitted into a bearing portion 2 integrally formed with a camshaft 1. As shown in FIG. In this fitting configuration, as shown in FIG.
A plurality of raised parts 3a are formed at row intervals on the inner periphery of the cam piece 3, and each raised part 2a of the bearing part 2 is located between each raised part 3a of the cam piece 3. It is assumed that a collar ball 4 is inserted between each side. Therefore, the cam piece 3 is movable in the axial direction relative to the camshaft 1, but rotates along the axial center together with the camshaft 1. The cam piece 3 includes a first cam 5 for low-speed rotation, a second cam 6 for high-speed rotation, and a timing mechanism 20 to be described later.
It has a flange-like member 8 that is always engaged with. Either one of the first and second cams 5.6 engages with the cam 7 lower 10 formed on the rocker arm 9 to control opening and closing of the pulp 11. The rocker arm 9 is rotatably supported by the shaft 12 of the rocker 7, and a lock nut 13 is attached to the swinging portion of the rocker arm 9.
Pulp gap adjustment through? The root 14 is installed. The projecting end 14a of the bolt 14 from the rocker arm 9 is in contact with the head of the valve 11. The valve 11 is always urged upward by a valve spring 16 fitted to the head or provided between the taker 15 and the cylinder block (not shown) so as to close the intake, exhaust, and exhaust pipes.

In the illustrated state, the first cam 5 controls the opening and closing of the pulp 11, the camshaft 1 rotates in the direction of arrow A (FIG. 2), and the protrusion of the first cam 5 engages with the cam follower 10. Then, the rocker arm 19 pushes down the valve 11 against the pulp spring 16, thereby opening the pulp 11.

A timing mechanism 20 is provided near the camshaft 1 and is capable of fixing the cam piece 3 in a fixed position. The timing mechanism 2o has a cylindrical fixing member 21 that is substantially parallel to the camshaft 1. The fixing member 21 is fixed to the cam case 24.25 via the holding member 22.23 in a substantially airtight manner, and the cam piece 3 is attached to the outer periphery of the cam case 24.25.
A driving member 26 that displaces the camshaft 1 along the axial direction of the camshaft 1 is slidably fitted therein. A plunger 2, which will be described later, is provided in the portion of the holding member 22 and 23 that faces into the fixing member 21.
Buffer members 28 and 29 are respectively attached to cushion the shock when the vehicle 7 collides with the vehicle.

The plunger 27 is slidably fitted inside the fixing member 21 in a substantially airtight manner, and the plunger 27 is slidably fitted inside the fixing member 21 to allow the left ventricle 30 to pass through the fixing member 21.
and the right ventricle 31. Plunge 92F0 both ends are
Other parts are also molded to a slightly smaller diameter. First and second escape holes 32 and 33, which are capable of communicating the left ventricle 30 and the right ventricle 31 with the atmosphere, and which are closed by the plunger 27, are provided below the side of the fixing member 21. Ru. 1st
In the position shown in FIG. 1 where the cam 5 engages with the rocker arm 9, the left chamber 30 communicates with the atmosphere through the first relief hole 32, and in the position where the second cam 6 engages with the rocker arm 9, the left chamber 30 communicates with the atmosphere through the first relief hole 32. , the right ventricle 31 communicates with the atmosphere via the second escape hole 33.

A bottle 35 screwed onto the drive member 26 is inserted into a radial hole 34 formed in the center of the plunger 27, thereby integrally coupling the disi-lunger 27 and the drive member 26. The bottle 35 is inserted through an elongated hole 36 formed parallel to the axial direction of the fixing member 21, and is movable while being regulated by the elongated hole 36. That is, plunger 27 and drive member 26 are prevented from rotating relative to fixed member 21 and are movable along this fixed member 21 .

A cylindrical portion 37 is formed on the opposite side of the drive member 26 from the bottle 35, and a timing syringer 3 is disposed within this cylindrical portion 37.
8 is slidably accommodated. Bin 3 in the radial hole 34
A spring 39 and a spherical engaging member 4 are provided on the end surface side portion of 5.
0 is accommodated. The locking member 40 is slidably supported within the radial hole 34 and is urged by a spring 39 to be in constant contact with the timing sylanger 38 .
8 is constantly engaged with the flanged member 8 that fits into the slit 41 formed in the cylindrical portion 37.

First and second locking holes 42 and 43 are bored in a portion of the fixing member 21 opposite to the elongated portion 36, and these locking holes 42 and 43 are connected by a narrow hole 44. . Locking hole 4
Reference numerals 2 and 43 have recesses at positions corresponding to both ends of the elongated hole 36, into which the locking members 40 can be deeply inserted. On the other hand, the slender width 440 is smaller than the diameter of the locking member 40, and only the timing plunger 38 can be inserted into this slender hole 44.

The brim member 8 of the cam piece 3 has a large diameter portion 8a and a small diameter portion 8b, as shown in FIG.

When the small diameter portion 8b engages with the timing plunger 38, the locking member 40 pushes up the timing plunger 38 and deeply fits into the locking hole 42 or 43, thereby firmly fixing the driving member 26 and the grunge 27 to the fixed member 21. Fixed to. On the other hand, when the large diameter portion 8a engages with the timing plunger 38, the locking member 40 is pushed down by the timing plunger 38 and shallowly fits into the locking hole 42 or the book 3. The locking forces of the member 26 and the plunger 27 with respect to the fixing member 21 are weakened. The large diameter portion 8a is configured to push down the timing plunger 38 at the same time that the cams 5 and 6 finish driving the rocker arm 9.

When the locking force of the locking member 40 to the fixing member 21 is weak, the plunger 27 moves in the left-right direction in the drawing by air pressure acting on the left chamber 30 or the right chamber 31. The first and second electromagnetic control valves 50, 51 supply compressed air to the left ventricle 30 and right ventricle 31, respectively. The first electromagnetic control valve 50 communicates with the left ventricle 30 via a passage 52 and with the pressure accumulator 70 via a passage 53. The second electromagnetic control valve 51 communicates with the right ventricle 31 via a passage 54 and with the pressure accumulator 70 via a passage 55 . , the second electromagnetic control valve 51 is connected to the passage 5
The valve body 57 accommodated in the housing 56 to which the passage 54.55 is connected is biased by a solenoid 58 and a spring 59 to open and close the passage 54.55.
．． 1? -) It is a solenoid valve. That is, when the solenoid 58 is not energized, the valve body 57 is biased by the spring 59 to block the passages 54 and 55, and when the solenoid 58 is energized,
The valve body 57 compresses the spring 59 and is attracted by the solenoid 58 to communicate the passages 54 and 55, and the pressure accumulator 7 is connected to the right chamber 31.
Introduce compressed air within 0. Note that the first electromagnetic control valve 50 also has the same configuration as the second electromagnetic control valve 51, so a description thereof will be omitted.

The pressure accumulator 70 is a conventionally known vane type air pump 7.
It is supplied with compressed air from 1 and stores this air. The suction lower 2 of the air pump shift 1 communicates with the atmosphere through a conduit and an air filter (not shown), and the air pump 71 pressurizes the air sucked in from the suction lower 2 and discharges it from the discharge lower 3. The pressure accumulator 70 is supplied via a conduit 75 . The check pulp 74 consists of a goal valve 76 and a spring 77. The pawl valve 76 is biased by a spring 77 to close the conduit 75, and the air pump 71
It is opened only when air with a certain pressure or higher is discharged, and high pressure air is guided to the pressure accumulator 70.

The first and second electromagnetic control valves 50 and 51 and the air pump 1 are driven by a computer 80. The computer 80 is connected to a pressure detector 81 provided in the pressure accumulator 70 via a conductor 82, and also receives a signal S! of the engine rotation speed. , a water temperature or oil temperature signal S', and an engine load signal Ss are input. Thus, the computer 80 drives the air pump 71 based on the signal from the pressure detector 81, and controls the pressure within the pressure accumulator 70 to a substantially constant value. The computer 80 also receives a signal Sl.

The following processing is performed based on S, , 8=, and if switching of the cam is necessary, one of the electromagnetic control valves 50, 51 is driven via the conductor 83, 84. That is, when the oil temperature is below a predetermined value, the first cam 5'f for low speed is used; Two cams 6 will be used. At this time, for example, regarding the engine rotation speed, the rotation speed Nl when switching from the first cam 5 to the second cam 6 is the rotation speed Nl when switching from the first cam 5 to the second cam 6.
2 is also higher, and hysteresis is provided, and hysteresis is also provided for the engine load.

Since the device of this embodiment has the above-described configuration, it operates as follows to switch between the cams 5 and 6.

In the state shown in FIGS. 1 and 2, the rocker arm 9
The first cam 5 for low speed is engaged with the solenoid control valve 5.
0.51 are both passages 52°53 and 54.55
are blocked respectively.

On the other hand, the locking member 4o of the timing mechanism 20 has a locking hole 43.
approximately 1/1/2 of the spherical diameter of the locking member 4o.
Only 2 are inserted. Therefore, the driving member 26 is fixed to the fixed member 21 and is not displaced in the axial direction of the fixed member 21. Thus, the cam piece 3 moves along the camshaft 1, and the first cam 5 rotates together with the camshaft 1 to drive the rocker arm 9 and open and close the pulp 11.

During this rotation of the camshaft 1, the flange-like member 8 of the cam piece 3 alternately engages the timing plunger 38 at the large diameter portion 8a and the small diameter portion 8b and pushes it down. When the small diameter portion 8b engages with the timing plunger 38, the locking member 40 is deeply inserted into the locking hole 43 as described above, but when the large diameter portion 8a engages with the timing plunger 38, the locking member 40 fits deeply into the locking hole 43 as described above. 40 is pushed down by the timing pusher 38 as shown in FIG. 4, and the depth of insertion into the locking hole 43 becomes shallow. However, as described above, the electromagnetic control valve 50.
51 is blocked, compressed air is not supplied to the left ventricle 30 and right ventricle 31, and the no-lunger 27 is not energized.
The drive member 26 is not displaced. Further, at this time, the drive member 26 does not move due to engine vibration or the like.

Now, for example, if the engine speed increases and it becomes necessary to switch to the second cam 6 for high speed, the computer 80
energizes the solenoid 58 to drive the electromagnetic control valve 51, displacing the valve body 57 and communicating the passages 54 and 55.

Air at a constant pressure is always stored in the pressure accumulator 7o via the air pump 71, and this air is supplied to the right ventricle 31 when the passages 54 and 55 are in communication. As a result, the plunger 29 is biased toward the left in FIG. If the locking member 4o of the timing mechanism 20 is deeply fitted into the locking hole 43 as shown in FIG. 2, the plunger 29 cannot move, and therefore the cam piece 3 is also fixed. Ru. In this case, it is a fixed period including the time when the cam 5 opens the intake and exhaust valves, and the cam piece 3 is not moved at this time.

When the camshaft 1 rotates further and the cam 5 closes the intake and exhaust valves, and the cam can be switched,
The large diameter portion 8a of the collar member 8 comes to engage with the timing plunger 38. Then, the locking member 40 is pushed down by the timing sylanger 38 to shallowly fit into the second locking hole 43, as shown in FIG. It moves to the left and stops at a position where the locking member 40 fits into the locking hole 42. As a result, the second cam 6 comes into engagement with the rocker arm 9, and the switching of the cams is completed.

During this movement of the plunger 27, the locking member 4° enters into the radial hole 34, and the timing plunger 38 enters the fifth
The slot 44 is engaged as shown in the Figures and FIG. 6, and the bottle 35 is guided into the slot 36 as shown in FIG. Therefore, the drive member 26 and the plunger 27 are smoothly displaced along the fixed member 21. Also, when the bottle 35 reaches the end of the elongated hole 36, the plunger 27
Since the end portion of the cam contacts the buffer material 28, it is possible to prevent collision noise from occurring when switching the cam, and also to prevent impacts from acting on the bottle 35 and the like, thereby improving their durability. Furthermore, at the end of this switching operation, the inside of the right ventricle 31 is communicated with the atmosphere via the relief hole 33, so the inside of the right ventricle 31 is quickly returned to atmospheric pressure, and the switching from the second cam 6 to the first cam 5 is performed. is also carried out smoothly.

Furthermore, according to this embodiment, the locked state of the timing mechanism 20 does not depend only on the elastic force of the spring 39, but is related to the fitted state of the locking member 40 and the locking holes 42, 43. Therefore, the spring 39 only needs to be designed so that the timing plunger 38, the locking member 40, and the brim member 8 are always in contact with each other at a fixed position where either of the cams 5.6 engages with the rocker arm 9. , there is no need to determine the spring constant with high precision. On the other hand, since the locking member 40 has a spherical shape, the contact area with the locking holes 42 and 43 is small, so when it is pressed against the large diameter portion 8a of the brim-shaped member 8, it retreats smoothly, and The responsiveness of the mechanism 2o is improved.

Note that switching from the second cam 6 to the first cam 5 is performed in exactly the same manner as described above, and in this case, the first electromagnetic control valve 5
It is sufficient to drive 0.

FIG. 8 shows a second embodiment. The locking member 40 is different from that of the first embodiment, and has a curved surface with a convex side surface.
The upper and lower surfaces are flat, and the overall shape is barrel-shaped. According to this second embodiment, the locking member 40 has a curved side surface, so that the contact area with the locking holes 42 and 43 is small.
Therefore, since the frictional resistance is small, it can be quickly released from the locking holes 42, 43. The other configurations are similar to those of the first embodiment, and detailed description thereof will be omitted.

FIG. 9 shows a third embodiment, in which in addition to being formed into a round side shape, the upper end surface of the locking member 40, that is, the surface that comes into contact with the timing plunger 38, is formed into a spherical shape. Further, in the fourth embodiment shown in FIG. 10, the locking member 40 has a rounded side surface and a lower end surface that contacts the spring 39 is formed into a spherical shape. Both are the above 1st
The same effects as in the embodiment are achieved.

It may be configured such that the navigation piece 3 is fixed and the rocker arm 9 is moved, and in this case, the timing mechanism 20 may be connected to the rocker arm 9.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a variable valve mechanism that can quickly switch cams and has a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the first embodiment of the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a sectional view similar to FIG. FIG. 4 is a cross-sectional view showing a state in which the fixing member is shallowly inserted into the locking hole; FIG. 4 is a cross-sectional view showing the same state as shown in FIG. 3;
The figure is a cross-sectional view showing the state in which the locking member is completely inserted into the radial hole and the plunger is moving, Figure 6 is a plan view showing the locking hole and the thin hole, and Figure 7 is the elongated hole. Floor plan, No. 8
9 is a sectional view showing the second embodiment, FIG. 9 is a sectional view showing the third embodiment, and FIG. 10 is a sectional view showing the fourth embodiment. 5... First cam, 6... Second cam, 8... Flange member, 8a... Large diameter part, 8b... Small diameter part, 9... Rocker arm (opening/closing member), 21...Fixing member, 27
...Plunger, 40...Heyo member, 42.43.
...Latching Hole, Patent Applicant Japan Auto Parts Research Institute Toyota Motor Co., Ltd. Patent Agent Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Kyo Nakayama Akira Yamaguchi Patent Attorney Nishi Masaya Yama 1st broom 2nd figure 6th figure 3 @ 4th painting 50 @ 6th figure 70 Continued from page 1 ■ Inventor Yoshimura Kokusei 0 Inventor Takao Narioka 0 Inventor Akira Hiyoshi Chikara

Claims (1)

[Claims] 1. An opening/closing member (9) that comes into contact with an intake and exhaust valve of an internal combustion engine;
First and second cams (516) that engage with the opening/closing member (9) to open and close the intake and exhaust valves;
, 6) or a fixing member (21) provided near the opening/closing member (9), and a fixing member (21) that is reciprocatably supported by the fixing member (21) and the cam (5, 6) or the opening/closing member (
9), and a locking member (40) supported by the plunger (27) and capable of being fitted into locking holes (42, 43) formed in the fixing member (21).
), and an urging mechanism (27) that urges the plunger (27) to move the cam (5, 6) or the opening/closing member (9) to switch the engagement relationship between the cam (516) and the opening/closing member (9). 50°51), the locking member (40) can change the depth of insertion into the locking hole (42, 43), and one of the cams (516) opens the intake and exhaust valves. The variable valve mechanism is characterized in that when the cam (5.degree. 6) or the opening/closing member (9) is moved, the insertion depth is increased to prevent movement of the cam (5.degree. 6) or the opening/closing member (9). 2. A collar-shaped member (8) having a large diameter portion (8a) and a small diameter portion (8b) is integrally connected to the cam (5, 6) or the opening/closing member (9), and is connected to the locking member (40). ) is always in contact with this collar-shaped member (8), and when engaging with the small diameter part (8b), the depth of insertion into the locking hole (42, 43) is deep, and when it engages with the large diameter part (8a). 2. The variable valve mechanism according to claim 1, wherein the insertion depth t into the locking hole (42, 43) is made shallow when the valve is inserted into the locking hole (42, 43). 3. The variable element according to claim 1 or 5 or 2, wherein the contact portion with the locking member (40 holes (42, 43) has a curved surface. Valve mechanism. 4. The variable valve mechanism according to claim 3, wherein the locking member (40) has a spherical shape.