JP2023056614A - Variable valve mechanism of internal combustion engine - Google Patents

Abstract

To eliminate necessity of providing an oil passage for a changeover pin actuation in a cylinder head.SOLUTION: A variable valve mechanism of an internal combustion engine includes: an input arm 20 that is oscillated by being pressed by a cam; an output arm 5 for pressing a valve V by being oscillated; a changeover pin 15 provided in the output arm 5 in a displaceable manner; and a driving device 30 for displacing the changeover pin 15 to an engagement position for causing the input arm 20 to engage with the output arm 5, and to a non-engagement position for causing the input arm 20 to be freely oscillated without causing the input arm to engage with the output arm 5. The driving device 30 includes a slide member 31, an actuator 37, a plate spring 38 for engagement whose base end part is fixed to the slide member 31, and tip part abuts on one end surface of the changeover pin 15 so as to press the changeover pin 15 toward the engagement position, and a plate spring 39 for non-engagement whose base end part is fixed to the slide member 31, and tip part abuts on the other end surface of the changeover pin 15 so as to press the changeover pin 15 toward the non-engagement position.SELECTED DRAWING: Figure 1

Description

The present invention relates to a variable valve mechanism for an internal combustion engine.

As one of switching type variable valve mechanisms for internal combustion engines, as described in Patent Documents 1 to 4, an input arm that is pressed by a cam to swing, an output arm that swings to press a valve, a switching pin displaceably provided on the output arm; an engaging position where the switching pin engages the input arm with the output arm; and a non-engaging position where the input arm is idled without engaging the output arm. Another type includes a displacing drive device and a lost motion spring for damping idle swing of the input arm when the switching pin is in the disengaged position.

As a driving device, there is often a combination of a hydraulic drive circuit that displaces the switching pin to the locked position when the engine oil pressure is ON, and a return spring that displaces the switching pin to the unlocked position by elastic force when the hydraulic pressure is OFF. The hydraulic drive circuit is often provided using a hydraulic lash adjuster that swingably supports the base end of the output arm. That is, as described in detail in Patent Document 1, two oil passages for operating the hydraulic lash adjuster and for operating the switching pin are formed in the cylinder head so as to both reach the hydraulic lash adjuster. , through an oil passage formed in the hydraulic lash adjuster and an oil passage formed in the output arm to reach the switching pin, forming a hydraulic drive circuit.

In the variable valve mechanism of Patent Document 1, the switching pin and the return spring are arranged at the tip of the output arm, and the hydraulic lash adjuster and the switching pin are separated, so a long oil passage is formed in the output arm. be.

In the variable valve mechanisms disclosed in Patent Documents 2 to 4, the switching pin and the return spring are arranged at the base end of the output arm, and since the switching pin is located directly above the hydraulic lash adjuster, the oil passage is short in the output arm. is formed.

WO2013/159120 U.S. Patent Application Publication No. 2014/0290608 U.S. Patent Application Publication No. 2015/0275712 JP 2017-166460 A

The variable valve mechanism described above has the following problems.
・Because it is necessary to add an oil passage for operating the switching pin to the cylinder head, it becomes a cylinder head dedicated to the variable valve, and it is difficult to share it with a conventional cylinder head. Also, a return spring is required.
・In addition, when the temperature is low immediately after starting the internal combustion engine, the viscosity of the engine oil is high and the switching operation of the switching pin is slow. Therefore, in many cases, a restriction such as starting switching control after warming up is provided.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to displace a switching pin between an engaging position and a non-engaging position by means of an engaging leaf spring and a non-engaging leaf spring that are stopped by a slide member that slides by an actuator, thereby displacing a cylinder. To eliminate the need to provide an oil passage for operating a switching pin in a head, to facilitate commonality with a cylinder head of a conventional non-variable valve system, and to eliminate a return spring. Furthermore, by using an electric actuator, the switching operation of the switching pin is accelerated immediately after the internal combustion engine is started.

The present invention comprises an input arm that swings when pressed by a cam, an output arm that swings and presses a valve, a switching pin that is displaceably provided on the output arm, a switching pin, and an input arm that is connected to the output arm. In a variable valve mechanism for an internal combustion engine, the variable valve mechanism for an internal combustion engine includes a driving device that displaces the input arm between an engagement position for engagement and a non-engagement position for idle swinging without engaging the input arm with the output arm,
The drive is
a slide member extending parallel to the central axis of the switching pin and slidable in the direction;
an actuator for sliding the slide member;
an engaging leaf spring whose base end portion is stopped by the slide member and whose tip portion is in contact with one end face of the switching pin to press the switching pin toward the engagement position;
and a non-engagement leaf spring whose base end is stopped by the slide member and whose tip end contacts the other end surface of the switching pin to press the switching pin toward the non-engagement position. do.

Here, the actuator is not particularly limited, but examples include electric actuators (eg, electromagnetic solenoids, motor actuators, linear actuators, etc.), hydraulic actuators (eg, hydraulic cylinders), and the like. However, by using the electric actuator, there is an advantage that the switching operation of the switching pin is quick regardless of the high viscosity of the engine oil at low temperature immediately after starting the internal combustion engine.

Also, any of the following aspects (1) and (2) may be used.
(1) When the switching pin is in the disengaged position and the input arm swings idle, the output arm swings by a cam different from the cam to press the valve.
(2) A mode in which the output arm does not swing and does not press the valve (rests) when the switching pin is in the disengaged position and the input arm swings freely.

The central axis of the switching pin is preferably in the width direction of the output arm. As a result, in a variable valve mechanism for a multi-cylinder internal combustion engine, a single slide member holds the proximal end portions of the engaging leaf springs and the non-engaging leaf springs corresponding to the valves of the plurality of cylinders. This makes it possible to switch a plurality of cylinders at once.

[Action]
Since the switching pin is displaced between the engaging position and the non-engaging position by the engaging leaf spring and the non-engaging leaf spring that are stopped by the slide member that slides by the actuator, an oil passage for operating the switching pin is provided in the cylinder head. There is no need to provide it, and it becomes easy to share with a cylinder head of a conventional non-variable valve system. Moreover, the return spring can also be abolished.

According to the present invention, the switching pin is displaced between the engagement position and the non-engagement position by the engagement leaf spring and the non-engagement leaf spring that are stopped by the slide member that slides by the actuator. It is possible to eliminate the need to provide an oil passage for operating the switching pin, facilitate commonality with a cylinder head of a conventional non-variable valve system, and eliminate a return spring.

FIG. 1 is a perspective view of an embodiment (a variable valve mechanism for a multi-cylinder internal combustion engine). FIG. 2 is a perspective view of the variable valve mechanism for one cylinder of the same embodiment. FIG. 3 is a perspective view of an input arm and an output arm of the same mechanism. FIG. 4 shows a slide member, an engaging leaf spring and a non-engaging leaf spring of the same mechanism, where (a) is an exploded perspective view before assembly, (b) is a perspective view after assembly, and (c) is a modification. It is a perspective view. FIG. 5(a) is a plan view of the same mechanism, and FIG. 5(b) is a sectional view taken along the line Vb-Vb. FIG. 6 is a VI-VI sectional view of the same mechanism. FIG. 7(a) is a VIIa-VIIa sectional view of the same mechanism, and (b) is a perspective view of a switching pin. FIG. 8(a) is a VIII-VIII sectional view of the same mechanism at a low lift, and (b) is a VIII-VIII sectional view at a high lift. FIG. 9 shows switching of the same mechanism, where (a) is a partial front view before switching, (b) is a partial sectional view during switching, and (c) is a partial front view after switching. FIG. 10 shows lift by the same mechanism, where (a) is a cross-sectional view taken along line XX at low lift and (b) is a cross-sectional view taken along line XX at high lift.

1. The portion of the input arm pressed by the input arm cam is not particularly limited, and may be, for example, a slipper that is a non-moving sliding surface or a rotatable roller.

2. Output Arm When the output arm is of the aspect (1) above, the portion pressed by another cam is not particularly limited, and may be, for example, a slipper that is a non-moving sliding surface or a rotatable roller.

3. Pin Hole and Switching Pin It is preferable that the pin hole and the switching pin are arranged at the base end of the output arm, which is on the swing center side. This is because the pin hole and the switching pin are less likely to vary in position due to swinging of the output arm, and the contact between the engaging leaf spring and the non-engaging leaf spring can be easily maintained, and the friction loss caused by the contact is also small.

Next, embodiments of the present invention will be described with reference to FIGS. 1 to 10. FIG. However, the structure, shape, quantity, etc. of each part to be described are examples, and can be changed as appropriate without departing from the spirit of the invention.

As shown in FIG. 1, the variable valve mechanism of this embodiment is provided in an internal combustion engine having a plurality of cylinders and two intake valves V (exhaust valves are not shown) per cylinder. It is.

The variable valve mechanism of this embodiment includes a high-lift cam 2, an input arm 20 that is pushed and swung by the high-lift cam 2, an output arm 5 that swings and presses the valve V, and a displaceable output arm 5. an engaging position where the switching pin 15 engages the input arm 20 with the output arm 5; and a drive device 30 for displacing it, and a low lift cam 3 for pressing the output arm 5 when the input arm 20 is not engaged.

The camshaft 1 is provided with a high-lift cam 2 having a relatively high nose protruding from the base circle and a pair of low-lift cams 3 having a relatively low nose protruding from the base circle, corresponding to each valve V. It is An input arm 20, an output arm 5 and a switching pin 15 are also provided corresponding to each valve V. As shown in FIG.

The output arm 5 is an outer arm, and, as shown in FIG. A base portion 8 connecting between the proximal ends of the two side walls 6, which are integrally formed. Between the middle portions of the two side walls 6 is a void. A lower surface of the action portion 7 is a valve pressing surface. The base 8 is slidably supported by a hydraulic lash adjuster 12 attached to the cylinder head. The base portion 8 is formed with a pin hole 9 extending in the width direction of the arm and penetrating therethrough, and a notch 10 exposing an intermediate portion of the pin hole 9 . Since the arm width direction is parallel to the central axis of the camshaft 1 , the central axis of the pin hole 9 is parallel to the central axis of the camshaft 1 .

The output arm 5 also functions as an input/output arm that is pushed by the low lift cam 3 to swing when the input arm 20 is not engaged. Specifically, a slipper 11 with which the low-lift cam 3 slides is provided at the upper ends of the two side walls 6 .

As shown in FIGS. 3, 7 and 8, the switching pin 15 has a cylindrical shape longer than the pin hole 9, and has left and right large diameter portions 16 with a large outer diameter and small diameter portions 17 at the intermediate portion with a small outer diameter. Consists of The switching pin 15 is displaceably inserted into the pin hole 9 , and both ends of the pin protrude from the pin hole 9 . C-rings as a right stopper 18 and a left stopper 19 are attached to both ends of the projecting pin, respectively. The central axis of the switching pin 15 extends parallel to the central axis of the camshaft 1 in the same manner as the pin hole 9 .

As shown in FIGS. 7A and 8A, when the switching pin 15 is displaced leftward and the right stopper 18 hits the side surface of the base portion 8, the small diameter portion 17 matches the notch 10, The switching pin 15 is positioned at the non-engagement position where the input arm 20 freely swings due to the projection 23 (to be described later) entering the small diameter portion 17 .

As shown in FIG. 8B, when the switching pin 15 is displaced to the right and the left stopper 19 hits the side surface of the base portion 8, the large diameter portion 16 is aligned with the notch 10, and the large diameter portion 16 The switching pin 15 is positioned at the engagement position where the input arm 20 is engaged with the output arm 5 by a projection 23 described later.

The input arm 20 is an inner arm, and is arranged in the space of the output arm 5 as shown in FIG. 3 and the like. The input arm 20 includes two side plates 21 extending in the front-rear direction and separated from each other in the width direction, and a rear portion 22 connecting the rear end portions of the two side plates 21, which are integrally formed. The tips of the two side plates 21 are rotatably attached to the tip of the side wall 6 of the output arm 5 by a swing shaft 24, so that the input arm 20 can swing with respect to the output arm 5. . The rear portion 22 is provided with a projection 23 projecting rearward so as to hang over the base portion 8 of the output arm 5 . A roller 25 is rotatably attached to the intermediate portion of the two side plates 21 by a roller shaft and a bearing, and the high lift cam 2 contacts the roller 25 .

A torsion coil spring is provided as a lost motion spring 26 that brakes idle swinging of the input arm 20 when the switching pin 15 is in the disengaged position. A coiled portion of the torsion coil spring is mounted around the base 8 of the output arm 5 . One arm portion extending from the end of the coil portion of the torsion coil spring is hooked on the side wall 6 of the output arm 5 and the other arm portion is hooked on the side plate 21 of the input arm 20 .

As shown in FIGS. 1, 2, 4, etc., the driving device 30
a slide member 31 extending parallel to the central axis of the switching pin 15 (also parallel to the central axis of the camshaft 1) and slidable in the direction;
an actuator 37 for sliding the slide member 31;
An engagement leaf spring 38 whose base end is stopped by the slide member 31 and whose tip end contacts one end surface of the switching pin 15 to press the switching pin 15 toward the engagement position;
A non-engagement leaf spring 39 whose base end is stopped by the slide member 31 and whose tip end contacts the other end surface of the switching pin 15 to press the switching pin 15 toward the non-engagement position. ing.

The engaging leaf springs 38 and the non-engaging leaf springs 39 are provided in numbers corresponding to the respective valves V. However, the slide member 31 and the actuator 37 are each configured to correspond to a plurality of cylinders, and the cost is reduced. advantage in terms of As described above, this configuration is possible because the central axis of the switching pin 15 is parallel to the central axis of the camshaft 1, and therefore the central axes of the switching pins 15 corresponding to the adjacent valves V are aligned on one straight line. It has become.

The slide member 31 has an elongated plate-like shape, and is formed with a leaf spring mounting hole 32 and an elongated hole 33 for slide guidance. A bolt 35 serving as a guide pin that is inserted into an elongated hole 33 is screwed to the upper part of a cam support 34 of the cylinder head. 31 are sandwiched with a clearance (gap that enables sliding). Thus, the slide member 31 can slide in the direction parallel to the central axis of the camshaft 1 within the range of the long hole 33 .

The actuator 37 slides the slide member 31 by pushing and pulling the end of the slide member 31 . In this embodiment, an electric actuator (such as an electromagnetic solenoid) is used as the actuator 37 .

As shown in FIGS. 4(a) and 4(b), the engaging leaf spring 38 and the non-engaging leaf spring 39 are integrated by a spring metal via a connecting plate 40 between their base ends (upper ends). formed and they are U-shaped. The engaging leaf spring 38 and the non-engaging leaf spring 39 are passed through the leaf spring mounting hole 32 of the slide member 31 from above and extend downward. The base ends of 38 and 39 are stopped by the slide member 31 .

4(c), the connecting plate 40 may be joined to the lower surface of the slide member 31 without forming the plate spring mounting hole 32 in the slide member 31. As shown in FIG.

The tip (lower end) of the engaging leaf spring 38 abuts the left end surface of the switching pin 15, and the tip (lower end) of the non-engaging leaf spring 39 abuts the right end surface of the switching pin 15. The pin 15 is sandwiched between the leaf springs 38 and 39 and moves in conjunction with the sliding of the leaf springs. Since the inner width between the engaging leaf spring 38 and the non-engaging leaf spring 39 is equal to or less than the total length of the switching pin 15, there is no backlash between the inner width and the total length of the switching pin 15. ing.

It is possible to set both the low lift mode and the high lift mode at the initial stage of starting the internal combustion engine, and switching between the two modes is possible in either setting.

(a) Low lift mode As shown in FIGS. 7(a), 8(a), 9(a), and 10(a), the switching pin 15 is displaced leftward by the non-engagement leaf spring 39. , and the small diameter portion 17 matches the notch 10 . Therefore, even if the high-lift cam 2 presses the roller 25 of the input arm 20, the input load to the roller 25 is applied only by entering the input arm 20 just before the projecting portion 23 hits the small diameter portion 17 and idling. is not transmitted to the output arm 5. The input load from the low lift cam 3 to the slipper 11 of the output arm 5 is transmitted to the output arm 5 as it is, and the output arm 5 lifts the valve V to a low level.

(b) High lift mode As shown in FIGS. 8(b), 9(b), and 10(b), the switching pin 15 is displaced to the right by the engagement leaf spring 38, and the large diameter portion 16 is aligned with notch 10 . Therefore, when the high-lift cam 2 presses the roller 25 of the input arm 20, the projecting portion 23 of the input arm 20 presses the large diameter portion 16, and the input load to the roller 25 is transmitted to the output arm 5. 5 lifts the valve V high. At this time, since the low lift cam 3 has a low nose, it does not hit the slipper 11 of the output arm 5 and is idling.

(c) Switching from low-lift mode to high-lift mode From the low-lift mode, the actuator 37 pulls the end of the slide member 31 to slide the slide member 31 rightward, and the engaging leaf spring 38 is switched. The left end face of pin 15 is pressed. However, when the protrusion 23 of the input arm 20 enters the small-diameter portion 17 due to the nose of the low-lift cam 3, the protrusion 23 interferes and the switching pin 15 cannot be displaced. As shown in (b), the engaging leaf spring 38 bends and accumulates elastic force. When the low-lift cam 3 becomes the base circle, the small diameter portion 17 of the protrusion 23 is pulled out, so that the switching pin 15 is displaced to the right by the elastic force stored in the engaging plate spring 38. Switch to high lift mode.

(c) Switching from high lift mode to low lift mode From the high lift mode, the actuator 37 pushes the end of the slide member 31 to slide the slide member 31 leftward, and the non-engagement leaf spring 39 is The right end surface of the switching pin 15 is pressed. However, when the protrusion 23 of the inner arm rests on the large-diameter portion 16 due to the nose of the high-lift cam 2, the switching pin 15 cannot move due to the force that the protrusion 23 presses against the large-diameter portion 16. , the engaging leaf spring 38 is curved to store elastic force. When the high-lift cam 2 becomes the base circle, the force of the protrusion 23 pressing the large-diameter portion 16 disappears or becomes very small. Displace to the left and switch to the low lift mode described above.

According to the rocker arm 1 of this embodiment, the following effects are obtained.
(a) Since the switching pin 15 is displaced between the engaging position and the non-engaging position by the engaging leaf spring 38 and the non-engaging leaf spring 39 which are stopped by the sliding member 31 by the actuator 37, the cylinder head can be displaced. Since it is not necessary to provide an oil passage for operating the switching pin 15, it is easy to share with a conventional non-variable valve system cylinder head. Moreover, the return spring can also be abolished.
(a) By using an electric actuator as the actuator 37, there is an advantage that the switching operation of the switching pin 15 is quick regardless of the high viscosity of the engine oil at low temperatures immediately after starting the internal combustion engine.
(c) The central axis of the switching pin 15 is in the width direction of the output arm 5, and one slide member 31 is provided with the engaging leaf springs 38 and the non-engaging leaf springs 39 corresponding in number to the valves V of a plurality of cylinders. The base end is stopped, and batch switching of multiple cylinders is possible.
(d) Since the switching pin 15 has a switching structure that allows rotation, it does not require a detent.

It should be noted that the present invention is not limited to the above-described embodiments, and can be embodied with appropriate modifications without departing from the gist of the invention.

REFERENCE SIGNS LIST 1 camshaft 2 high lift cam 3 low lift cam 5 output arm 8 base 9 pin hole 10 notch 15 switching pin 16 large diameter portion 17 small diameter portion 20 input arm 23 protrusion 25 roller 30 drive device 31 slide member 32 leaf spring mounting hole 33 length hole 37 actuator 38 leaf spring for engagement 39 leaf spring for non-engagement 40 connecting plate V valve

Claims (6)

An input arm (20) that swings when pressed by a cam (2), an output arm (5) that swings and presses a valve (V), and a switching pin displaceably provided on the output arm (5). (15), the switching pin (15) is set to an engagement position where the input arm (20) is engaged with the output arm (5), and an idle position where the input arm (20) is not engaged with the output arm (5). A variable valve mechanism for an internal combustion engine, which includes a disengaged position for swinging and a driving device for displacing,
The drive (30) is
a slide member (31) extending parallel to the central axis of the switching pin (15) and slidable in the direction;
an actuator (37) for sliding the slide member (31);
An engagement leaf spring (38) whose base end is stopped by the slide member (31) and whose tip end contacts one end surface of the switching pin (15) to press the switching pin (15) toward the engagement position. and,
A non-engagement leaf spring (a non-engagement leaf spring whose base end is stopped by the slide member (31) and whose tip end contacts the other end surface of the switching pin (15) to press the switching pin (15) toward the non-engagement position). 39) A variable valve mechanism for an internal combustion engine, characterized by comprising: A variable valve mechanism for an internal combustion engine according to claim 1, wherein the actuator (37) is an electric actuator. When the switching pin (15) is in the disengaged position and the input arm (20) swings idle, the output arm (5) swings by the cam (3) different from the cam (2). 3. A variable valve mechanism for an internal combustion engine according to claim 1 or 2, configured to press the valve (V). The output arm (5) does not swing and presses the valve (V) when the switching pin (15) is in the disengaged position and the input arm (20) swings freely. 3. A variable valve mechanism for an internal combustion engine according to 1 or 2. A variable valve mechanism for an internal combustion engine according to any one of claims 1 to 4, wherein the central axis of the switching pin (15) is in the width direction of the output arm (5). A variable valve mechanism for a multi-cylinder internal combustion engine, wherein one slide member (31) is provided with engaging leaf springs (38) and non-engaging leaf springs (39) corresponding to the number of valves (V) of the plurality of cylinders. 6. A variable valve mechanism for an internal combustion engine according to claim 5, wherein each base end of ) is stopped.

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