JPS60111008A - Switching device of valve actuating cam in internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent a rise of surface pressure in a cam when it is switched, by causing the protrusive part of a flange-shaped member, provided in the cam, to engage a plunger with a fixed member so as to prevent the cam from moving when a valve is opened. CONSTITUTION:A cam piece 3, having two kinds of cams 5, 6, is movably provided on a cam shaft 1 and switched by moving a shaft 28 in a fixed member 17 in the axial direction through a driving part 18. A ratchet mechanism 19, being provided between the driving part 18 and the fixed member 17, prevents movement of the cam when it opens a valve 11 by causing a protrusive part 8a in a flange-shaped member 8 to press a ratchet pin 21 and a timing plunger 22 to be fitted into an engagement hole of the fixed member 17. The mechanism 19, lifting the pin 21 due to movement of the shaft 28 and lifting also the plunger 22 when a small contour part 8b of the flange-shaped member 8 is brought into contact with the plunger 22, allows the cam to move.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an internal combustion engine equipped with two or more cams for opening and closing intake and exhaust valves. , relates to a cam switching device that controls the opening/closing timing of the intake and exhaust valves and their lift t-i.O Prior Art As is well known in the art, an internal combustion engine controls the opening/closing timing of the intake and exhaust valves and its lift t-i according to its operating state. By switching the lift amount, fuel consumption can be reduced and driving performance can be significantly improved. As a means of switching the opening/closing timing and lift control, a cam that controls the opening/closing of the intake and exhaust valves is used as an example.
Two types of motors are known: one for high speed and one for low speed.

These cams must be switched at a time when the rocker arm is not pushing open the intake and exhaust valves via each cam. This is to suppress an increase in the surface pressure between the cam surface and the rocker arm contact ml, to prevent damage to the cam or the rocker arm corner, and to reduce hitting noise when switching the cam. In order to perform this kind of operation,
A mechanism is required to instantaneously move the cam inside the common base of both cams when the intake and exhaust valves are not lifted, that is, are not opened.

Purpose of the Invention The present invention has been devised in response to the above-mentioned requirements.In an internal combustion engine having two cams for switching the opening/closing timing and the lift amount of the intake/exhaust valve, each cam is configured to It is an object of the present invention to provide a simple and compact valve-operated cam switching device that can reliably switch cams when an exhaust valve is not open.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention includes an opening/closing member that cooperates with intake and exhaust valves of an internal combustion engine, and an opening/closing member that is fitted onto a camshaft, rotates together with the camshaft, and rotates in the axial direction of the camshaft. first and second cams that are movable and selectively engage the opening/closing member to open and close the intake and exhaust valves; a biasing mechanism; and a ratchet mechanism that fixes any of the cams at a position where they engage with the opening/closing part control, and the ratchet mechanism includes a fixing member provided substantially parallel to the camshaft. It is attached so that it can reciprocate in both parallel and perpendicular directions to the axial direction of the fixed member, and has two levels of strength: a lock that cannot be moved parallel to the axial direction and a lock that is movable in parallel to the axial direction. furthermore, one end of the ratchet mechanism is connected to the biasing mechanism provided on the fixed member, and the other end is connected to the first and second cams, respectively; The degree of engagement of the ratchet mechanism with respect to the fixed member is switched in synchronization with the rotation of the camshaft, so that when the eleventh and second cams do not open the intake and exhaust valves, both the cams and the opening/closing member are in a locked position. The present invention is characterized in that it is configured to perform switching.

Furthermore, according to a preferred embodiment of the present invention, the ratchet mechanism includes a drive part slidably fitted in the axial direction of the fixed member, a cylindrical part connected to the drive part, and a cylindrical part connected to the drive part. A ratchet pin and a timing granger are each slidably housed in the portion and are connected to each other via a spring. The ratchet pin and the timing granger have a small diameter part that engages with the moving groove, and a large diameter part that cannot be engaged with the moving groove but can be engaged with the specified groove. Further, the timing plunger is configured to abut on a flange-like member having a large diameter portion and a small diameter portion that are integrally and coaxially attached to the first and second cams.

Example The present invention will be described in detail below with reference to the drawings.

In FIGS. 1 and 2, a cam piece 3 is fitted into a bearing portion 2 formed on a camshaft 1. As shown in FIG. As shown in FIG. 2, crests 2a are formed at equal intervals on the outer periphery of the bearing portion 2, and raised portions 3a are formed at equal intervals on the inner periphery of the cam piece 3.

Each mountain portion 2a is located between each raised portion 3a of the cam piece 3, and a steel ball 4 is inserted between each side portion of these mountain portions 2a and the raised portion 3a. Therefore, the cam piece 3 is movable in the axial direction with respect to the camshaft 1, but rotates together with the camshaft 1 around the axis. The cam piece 3 includes a first cam 5 for high-speed rotation, a second cam 6 for low-speed rotation,
It has a flange-like member 8 that is always abutted and engaged with a ratchet mechanism 19 that will be described later. The first and second cams 5 and 6 each contact a cam follower 10 formed on the rocker arm 9 to control the opening and closing of the valve 11.

The rocker arm 9 is rotatably supported by the rocker shaft 12, and a valve clearance adjustment bolt 14 is attached to the swinging end of the rocker arm 9 via a lock nut 13. The protruding end 14a of the bolt 14 from the rocker arm 9 Hits the head. The valve 11 is always urged upward to close the intake and exhaust valves by a valve spring 16 fitted to the head or provided between the taker 15 and a cylinder block (not shown). In the illustrated state, the first cam 5 controls the opening and closing of the valve 1, and when the camshaft 1 rotates in the direction of the arrow and the protrusion of the first cam 5 engages the cam follower 10, the rocker arm 9 The valve 11 is pushed down against the pulp spring 16 to open the valve 11.

A cylindrical fixing member 17 is provided near the camshaft 1 and substantially parallel thereto. This fixing member 17 is fixed to a machine frame (not shown), and a drive part 18 for displacing the cam piece 3 along the camshaft 1 is slidably fitted on the outer periphery. A ratchet mechanism 19 is configured on the cam piece 3 side of the drive unit 18.

The ratchet mechanism 19 has a cylindrical portion 2 connected to the drive portion 18.
0, and a ratchet pin 2 is provided inside this cylindrical portion 20.
1 and a timing plunger 22 are each slidably housed therein, and a spring 23 is provided between the ratchet pin 21 and the timing plunger 22. As shown in FIGS. 3(a) and 3(b), this ratchet pin 21 has a large diameter portion 21a and a small diameter portion having a width across flats portion 21b obtained by cutting two sides of the large diameter portion 21a. The large diameter portion 21a can fit into the defined grooves 24a and 24b at both ends of the guide groove 240 provided along the axial direction of the cylindrical fixing member 17 as shown in FIG. moving groove 24c
On the other hand, the small diameter portion having the width across flats portion 21b is large enough to pass through the moving groove 24c due to the width across flats portion 21b. Therefore, it is necessary to insert the ratchet pin 21 into the cylindrical portion 22 so that the width across flat portion 21b and the moving groove 24c fit into each other.
The engagement between the pin 25 and a groove 21c provided on the outer periphery of the ratchet pin 21 in the axial direction defines the insertion direction of the ratchet pin 21 and prevents the ratchet pin 21 from rotating.

On the other hand, the timing plunger 22 can be slidably fitted into the ratchet bin 21 as shown in FIG.
It has a large diameter part 22a at its lower end that cannot be fitted into the moving groove 24c of the fixed member 17 shown in the figure, and a small diameter part 22b above it which can fit into this moving groove 24c.

A slit 27 formed on the cam piece 3 side of the cylindrical portion 20
The flanged member 8 is fitted inside, and the end surface of the flanged member 8 is in constant contact with the timing plunger 22.

A shaft 28 connected to an actuator such as a hydraulic piston (not shown) is provided inside the fixed member 17 so as to be movable forward and backward. A ring 29 is fitted on the shaft 28 at a position corresponding to the drive section 18, and retaining rings 30, 31 are fitted at positions spaced apart from the ring 29 by a certain distance. Slightly compressed springs 32, 33 are provided between the ring 29 and the retaining rings 30, 31, respectively. These springs 32 and 33 generate a driving force for moving the cam piece 3, as will be described later. The groove 34 carved in the shaft 28 has sloped parts 34a on both sides along the axial direction, and a flat part 34c in the center of the groove 34b1. That is, when in the neutral position, it is configured to be located near the flat portion 34c of this groove 34.

The ratchet pin 21 inserted into the cylindrical part 2o connected to the drive part 18 fits into the guide groove 24 provided in the cylindrical fixing part 17, protrudes from the cylindrical part, and enters the fixing part 17. The slot portion 4 inserted into the ring 29 and bored into the ring 29
1 and engages with the groove 34. Is this ratchet bin 21 the guide? ? By inserting the inside of 924, the drive unit 1
8 does not rotate relative to the fixed member 17.

When the shaft 28 moves in the direction of arrow B, the spring 32 is bent and the ring 29 is biased in the direction of arrow B.
The drive section 18 does not move while it is in contact with the movement groove 24c of the guide groove 24 (Fig. 5a). shaft 28
When the ratchet 21 moves further, the ratchet 21 is pushed up by the inclined part 34& of the groove 34 of the shaft 28, and its width across sides 21b fits into the moving groove 24c of the guide groove 24, and the driving part 18 is moved by the elastic force of the spring 32. It becomes possible to move around. In this movable state, the flange-like member 8 comes into contact with the timing plunger 22 as described above (this flange-like member 8 has a large diameter portion 8a and a small diameter portion 8b), and the flange-like member When the small diameter portion 8b of the timing plunger 22 comes into contact with the timing plunger 22, the moving groove 24c and the large diameter portion 22a at the lower end of the timing plunger 22 come into contact with each other, so that the drive portion 18 cannot move, resulting in the state shown in FIG. 5b. However, when the large diameter portion 8a of the brim member 8 comes into contact with the timing plunger 22, the timing plunger 22 is pushed down and the small diameter portion 22
b fits into the movement groove 24c, and the timing plunger 22
is movable along the movement groove 24c together with the ratchet pin 21, so the driving part 18 can be moved by the elastic force of the spring 32 (Fig. 5c), and the cam piece 3 is moved along its axis with respect to the camshaft 1. direction, and the cam is switched from the first cam 5 to the second cam 6 (Fig. 5d).

Next, the operation of this embodiment will be explained.

From the illustrated state in which the first cam 5 for high-speed rotation is in contact with the rocker arm 9, the cam 6 for low-speed rotation is in contact with the rocker arm 9.
The switching to the state in which it comes into contact with is performed as follows.

In this illustrated state, the ratchet bin 210 large diameter portion 2
1a is the regulation of the guide groove 24 of the fixing member 17? 424a and is in contact with the moving groove 24c (Fig. 5a),
The drive part 18 does not move relative to the fixed member 17. Therefore, the cam piece 3 is not displaced in the axial direction of the camshaft 1, and the first cam 5 can reliably drive the rocker arm 9.

Then, when the engine speed decreases and a switching signal is issued to the second cam 6 for low-speed rotation, this causes the shaft 2
8 moves in the direction of arrow B via the actuator. When the inclined portion 34a of the groove 34 pushes up the ratchet pin 21 due to the movement of the shaft 28, the width across flat portion 21b fits into the movement Ii'#24c of the guide groove of the fixed member 17,
Due to the elastic force generated in the spring 32, the drive section 18 becomes movable relative to the fixed member 17 (FIG. 5b).

On the other hand, the flanged member 8 is in constant contact with the timing plunger 22, and its small diameter portion 8b is in contact with the timing plunger 22.
When it comes into contact with the moving groove 24c and the timing plunger 22
The drive unit 18 cannot be moved because it comes into contact with the large diameter portion 22a at the lower end of the drive unit (Fig. 5b). However, when the large diameter portion 8a of the brim member 8 comes into contact with the timing plunger 22, the timing plunger 22 is pushed down and its small diameter portion 22b fits into the moving groove 24c, so that the ratchet pin 21
At the same time, the timing plunger 22 becomes movable along the movement groove 24c, and the driving portion 18 is displaced by the elastic force of the spring 32 (FIG. 5C). As a result, the ratchet pin 21 descends while engaging with the groove 34 and moves into the moving groove 2.
4c in parallel to the axial direction of the fixing member 17, and is locked in another defined groove 24b formed on the opposite side to the defined groove 24a (Fig. 5d).

At the same time, the cam piece 3 moves together with the p1 drive section 18 because the brim member 8 is held in the slit 27, and the second cam 6 comes to engage with the rocker arm 9.

Switching from the second cam 6 to the first cam 5 is also performed in exactly the same manner.

FIG. 6 shows the amount of radial protrusion of the first cam 5, the second cam 6, and the flange portion 8, and the timing of their operation. In this example, the first cam 5 is Compared to the second cam 6, the operation start time is earlier and the operation end time is later. That is, the first cam 5 drives the rocker arm 9 in the c-d section, and the corresponding portion of the second cam 6 is located inside this c-d section. On the other hand, the flange 8 is a
The -b section corresponds to the large diameter section 8a, and the other sections correspond to the small diameter section 8b. This a-b corresponding to the large diameter portion 8a
The section is immediately after the c-d section and is a certain value ahead of the next operation start timing C' of the first cam 5.

As can be understood from FIG. 6, as soon as the first cam 5 finishes driving the rocker arm 9, the large diameter portion 8a of the brim member 8 moves to the timing plunger 22 of the ratchet mechanism 19.
If the shaft 28 is already moving at this time, the cam piece 3 will be switched in the section a-b.

When the camshaft 1 further rotates, the small diameter portion 8b of the collar member 8 engages with the timing plunger 22, and the large diameter portion 22a of the timing plunger 220 of the ratchet mechanism 19 comes into contact with the moving groove 24c of the fixed member 17, so that the cam piece 3 You will not be able to move.

Here, the period b-c' needs to be longer than the time required for the cam piece 3 to switch, and the elastic force of the springs 32 and 33 of the movable parts such as the drive unit 18 and the camshaft 11 at the time of switching are
It changes depending on the rotation speed etc.

Although the above embodiment is a case of a German valve, the case of a plurality of valves can be easily realized by combining similar configurations.

Effects of the Invention As described above, according to the present invention, when a predetermined cam is operating an intake/exhaust valve, this operation is fixed to ensure that the predetermined operation of the intake/exhaust valve is performed, and the cam The switching of
This can be done reliably when the cam is not opening the intake/exhaust valve, so it suppresses the increase in surface pressure between the cam surface and the rocker arm contact surface, prevents damage to the cam or rocker arm corner, and prevents damage to the cam or rocker arm corner. It is possible to obtain a valve actuation cam switching device for an internal combustion engine, which has a simple configuration and can reduce the tapping noise of the engine.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway plan view of an embodiment of the present invention, FIG. 2 is a partially cutaway side view of the same embodiment, FIG. 3 is a ratchet pin in the same embodiment, and (a) is a front view thereof. ,(b)
is a side view of the same, FIG. 4 is a front view of the timing granger 22 in the above embodiment, and FIGS. 5a to 5d show the relationship between the ratchet pin, the timing granger, and the guide groove in the above embodiment. Figure 5a shows a state in which the ratchet pin and timing plunger are fixed in the specified groove of the guide groove, Figure 5b shows a state in which only the ratchet pin is movable along the movement groove of the guide groove, and Figure 5c shows the above-mentioned condition. A state in which both can move pJ along the movement groove,
Fig. 5d shows a state in which both of them are fixed in position in other prescribed grooves of the guide groove, and Fig. 6 shows the first cam, second cam, and flange member in the same embodiment. It is a graph showing the magnitude of the amount of protrusion in each radial direction and its operation timing. l...Camshaft, 3...Cam piece, 5...
First cam, 6... Second cam, 8... Flange member, 9...
... Rocker arm, 11 ... Intake and exhaust valve, 17 ... Fixed member, 18 ... Drive section, 19 ... Ratchet mechanism, 20 ... Cylindrical part, 21 ... Ratchet pin, 22
...Timing plunger, 24...Guide groove, 24
a, 24b...regular groove, 24c...movement groove, 28.
...shirt), 32.33...spring. Patent Applicant Japan Auto Parts Research Institute Co., Ltd. Toyota Motor Corporation Patent Application Representative Patent Attorneys Akira Aoki, Patent Attorney Kazuyuki Nishidate, Patent Attorney Kyosuke Nakayama, Patent Attorney Akira Yamaguchi, Patent Attorney Masaya Nishiyama 1st Figure 2 (a) (b) Figure 4 2 Continuation of page 1 @ Inventor Teruo Kumai Toyota City 0 Inventor Chikara Hiyoshi Toyota City Inventor Hideo Nakamura Toyota City

Claims (1)

[Scope of Claims] 1. An opening/closing member that cooperates with intake and exhaust valves of an internal combustion engine, and the opening/closing member is fitted onto a camshaft, rotates together with the camshaft, and is movable in the axial direction of the camshaft. first and second cams that selectively engage with the intake and exhaust valves to open and close the intake and exhaust valves, an urging mechanism that urges these cams to move along the camshaft, and any of the cams described above. is provided with a ratchet mechanism for fixing these cams at a position where they engage with the opening/closing member, and the ratchet mechanism is axially parallel to and irradiated with respect to a fixing member provided substantially parallel to the camshaft. *It is installed so that it can reciprocate in both directions of the f angle, and can be switched to two levels of strength and weakness: engagement that cannot be moved in parallel to the axial direction of the fixed member, and engagement that is movable in parallel to the axial direction. Further, one end of this ratchet mechanism is connected to the urging mechanism provided on the fixed member, and the other end is connected to the first and second cams, so that the rotation of the camshaft is switching the degree of engagement of the ratchet mechanism with respect to the fixed member in synchronization with the above, and switching the engagement position between the two cams and the opening/closing member when the intake and exhaust valves are not opened by the first and second cams; A valve actuation cam switching device for an internal combustion engine, characterized in that it is configured to 2. The ratchet mechanism includes a drive portion slidably fitted in the axial direction of the fixed member, a cylindrical portion connected to the drive portion, and a cylindrical portion slidably housed within the cylindrical portion. A ratchet pin and a timing plunger are connected to each other via a spring. The bottle and the timing plunger each have a small diameter portion that engages with the movement groove and a large diameter portion that cannot engage with the movement groove but can engage with the regulation groove, and the timing plunger has a small diameter portion that engages with the movement groove. Claim 1, characterized in that the cam is in contact with a flange-like member having a large diameter portion and a small diameter portion that are integrally and coaxially attached to the first and second cams.
A valve actuation cam switching device for an internal combustion engine as described in .