JPH0578907U - Engine valve mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] A valve operating mechanism that can change cylinder deactivation or valve timing facilitates return from cylinder deactivation to full cylinder operation or valve timing change, and prevents valve jumping. To do. [Structure] A rocker arm 2 whose front end abuts on a cam 6 and whose base end is rotatably supported by a rocker shaft 1, and piston holes 1a and 2c which are diametrically formed at the base ends of the rocker shaft and rocker arm. A tip end 3b of the rocker arm 3 of the engine valve mechanism including a piston 13 that is fitted to couple or release the two, and a rocker arm 3 whose base end is fixed to a rocker shaft and whose tip end contacts the stem head 9a of the valve. A spring 21 is provided between the side and a portion 20 irrelevant to the movement of the valve mechanism to press the rocker arm 3 against the stem head 9a only in the initial stage of lift.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine valve operating mechanism, and more particularly to an engine valve operating mechanism suitable for an engine capable of changing a cylinder deactivation or valve timing according to an operating state of the engine.

[0002]

[Prior Art]

 A car does not need that much power when traveling on a general road, and it is sufficient if it uses half of the power of the engine installed. Therefore, in such an operating state, it is possible to save energy by stopping a part of the engine (deactivating the cylinder) to reduce an excessive output. Therefore, in a multi-cylinder engine, the valve operating mechanism of the cylinder to be stopped is stopped, and also the fuel supply is stopped. For example, in the case of a 4-cylinder engine, half of the two cylinders are stopped (cylinder deactivation). There is a variable cylinder engine. In such a variable cylinder engine, the rocker arm of the cylinder for which the valve mechanism function is desired to be stopped is oscillated to stop the intake / exhaust valve movement.

11 and 12 show an example of a valve mechanism of a four-valve variable cylinder engine on the intake valve side, in which a rocker shaft 1 is rotatably fitted to a base end 2a of a rocker arm 2. Further, the base ends 3a and 4a of the two rocker arms 3 and 4 are fitted and fixed on both sides of the base end 2a of the rocker arm 2 of the rocker shaft 1. A roller 5 is axially supported at the tip of the rocker arm 2, and the roller 5 is in rolling contact with a cam 6. The tips 3b and 4b of the rocker arms 3 and 4 are in contact with the stem heads 9a of the intake valves 9 (only one valve is shown in FIG. 11) via the adjusting screws 7 and 8, respectively.

As shown in FIG. 11, piston holes (hereinafter simply referred to as “holes”) 1 a and 2 c are formed in the rocker shaft 1 and the rocker arm 2 in the diameter direction, and the rocker shaft 1 has holes 1 a. The piston 13 is slidably fitted in the axial direction, and a spring 14 is contracted between the base end of the piston 13 and the open end on one side of the hole 1a. When the hydraulic pressure is not applied, the piston 13 is pushed out of the hole 1a by the spring force of the spring 14, and its tip is fitted into the hole 2c of the rocker arm 2 to connect the rocker arm 2 and the rocker shaft 1. As a result, as the cam 6 rotates, the rocker arms 3 and 4 swing via the rocker arm 2 and the rocker shaft 1 to drive the respective valves 9.

When the piston 13 is pushed into the hole 1a against the spring force of the spring 14 by hydraulic pressure, the tip of the piston 13 is disengaged from the hole 2c of the rocker arm 2 and the connection between the rocker arm 2 and the rocker shaft 1 is released. To be done. As a result, the rocker shaft 1 becomes free with respect to the rocker arm 2, and even if the rocker arm 2 swings as the cam 6 rotates, the rocker arms 3 and 4 stop without swinging, and each valve 9 , It is kept stopped (valve closed). Therefore, the cylinders of these valves 9 are stopped (deactivated). Further, the lost motion assembly 16 prevents the rocker arm 2 from jumping up when the cylinder is stopped.

[0006]

[Problems to be solved by the device]

 However, in the valve operating mechanism having the above structure, when the valve 9 is in a stopped state, that is, when the tip of the piston 13 is disengaged from the hole 2c of the rocker arm 2, the rocker arm 2 and the rocker shaft 1 are rubbed by the frictional force. The shaft 1 rotates with the rocker arm 2. That is, since the rocker arms 3 and 4 integrated with the rocker shaft 1 are restricted by the valve end in the ascending section of the cam 6, the rocker shaft 1 does not rotate, but the rocker arms 3 and 4 are free to move up. Therefore, the rocker shaft 1 rotates in the descending section of the cam 6, and the phase between the hole 2c of the rocker arm 2 and the piston 13 remains deviated. This deviation is maintained even between the base circles of the cam 6, and it becomes difficult to fit the piston 13 into the hole 2c of the rocker arm 2, and as a result, the valve 9 is smoothly returned from the stopped state to the operating state. It becomes extremely difficult, and in some cases it may not be possible to recover.

The present invention has been made in view of the above-mentioned points, and in the engine capable of changing the cylinder deactivation or the valve timing, the valve operating mechanism returns from the cylinder deactivation operation to the all cylinder operation, or the valve timing. The purpose of the present invention is to provide an engine valve mechanism that can smoothly change the engine.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, in the present invention, a first rocker arm having a tip contacting a cam and a base end pivotally supported by a rocker shaft, and the rocker shaft and the base end of the rocker arm are respectively diametrically oriented. An engine having a piston fitted in a piston hole bored in the cylinder to couple or release the two; and a second rocker arm having a base end fixed to the rocker shaft and a tip abutting against the system head of the valve. In the valve mechanism, an urging means interposed between the tip end side of the second rocker arm and a portion irrelevant to the movement of the valve mechanism is provided to press the tip end of the second rocker arm against the stem head. The urging means is provided so as to apply the urging force only before the valve is lifted or from before the lift to the early stage of the lift. It was assumed that gradually decreases with the door.

[0009]

[Action]

 The tip of the second rocker arm is pressed against the stem head of the valve by an urging means such as a spring, so that the second rocker arm is prevented from jumping up when the cylinder is at rest. As a result, the piston holes of the first rocker arm and the rocker shaft are always kept in a matched state when the cylinder is deactivated, and the piston pulled into the piston hole of the rocker shaft is easily fitted into the piston hole of the first rocker arm. It becomes possible. This allows a smooth return from the cylinder deactivated state to the operating state. Further, since the urging force of the urging means acts only before the valve is lifted or at the initial stage of the valve lift, the valve jump during the lift is also prevented.

[0010]

【Example】

 An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The same members as those in FIGS. 5 and 6 are designated by the same reference numerals, and detailed description thereof will be omitted. 1 and 2, a supporting portion 20 is provided at one of the rocker arms 3 and 4 to which the base ends 3a and 4a are fixed, for example, at a position slightly above the base end 3a of the rocker arm 3. The support portion 20 is integrally formed with a portion unrelated to the movement of the valve mechanism, for example, a cylinder head (not shown) in which the valve mechanism is arranged. The spring 21 as an urging means is, for example, a strip-shaped leaf spring, the base end of which is fixed to the end surface of the support portion 20 by a bolt 22, and is curved in the vicinity of the base end and the upper surface 3c of the rocker arm 3 is bent. Along the direction toward the tip 3b, and the tip is pressed against the substantially center of the upper surface 3c.

The spring 21 presses the upper surface 3 c of the rocker arm 3 to press the rocker arm 3 and the rocker arm 4 so as to rotate clockwise around the rocker shaft 1 in the figure. The initial load of the spring 21 is set to a value larger than the torque due to the frictional force between the rocker arm 2 and the rocker shaft 1 to prevent the rocker shaft 1 from being rotated by the rocker arm 2. There is.

Further, as shown in FIG. 3, the spring force of the spring 21 becomes weaker (gradually decreases) as the lift amount of the valve 9 increases, that is, as the rocker arm 3 rotates downward. The spring force is not applied when the lift amount is exceeded.

When no hydraulic pressure is applied, the piston 13 is pushed out of the hole 1 a of the rocker shaft 1 by the spring force of the spring 14, and its tip is fitted into the hole 2 c of the rocker arm 2 to connect the rocker arm 2 and the rocker shaft 1 to each other. To do. As a result, as the cam 6 rotates, the rocker arms 3 and 4 swing via the rocker arm 2 and the rocker shaft 1 to drive the valves 9.

At the time of cylinder deactivation, the piston 13 is pushed into the hole 1 a of the rocker shaft 1 against the spring force of the spring 14 by hydraulic pressure, and the tip end thereof is disengaged from the hole 2 c of the rocker arm 2. As a result, the connection between the rocker arm 2 and the rocker shaft 1 is released, the rocker shaft 1 becomes free with respect to the rocker arm 2, and even if the rocker arm 2 swings as the cam 6 rotates, the rocker arms 3 and 4 are The valve 9 remains stopped without swinging, and each valve 9 is held in a stopped (valve closed) state. Therefore, the cylinders of these valves 9 are stopped (deactivated).

In the ascending section of the cam 6, the rocker arms 3 and 4 integrated with the rocker shaft 1 are restricted to the valve ends, so that the rocker shaft 1 does not rotate. Further, the rocker arms 3 and 4 are prevented from springing up in the descending section of the cam 6 because the tips 3b and 4b are pressed against the stem heads of the valves 9 by the spring force of the spring 21, and therefore, The rocker shaft 1 is prevented from being rotated by the rocker arm 2. As a result, the hole 2c of the rocker arm 2 and the piston 13 are held in a matched state in the base circle section of the cam 6 at the time of cylinder deactivation, and the piston 13 can be fitted into the hole 2c of the rocker arm 2 at its front end. It is in a state. This makes it possible to smoothly return the valve 9 from the stopped state to the operating state.

Since the biasing direction of the spring 21 is opposite to the biasing direction of the valve spring 31, it is assumed that the biasing force of the spring 21 is always applied when the valve 9 is lifted, as shown in FIG. In addition, when the valve is driven, the spring force is added to the inertial force of the valve 9, and the valve 9 itself jumps up, so that desired valve operating characteristics cannot be obtained. Therefore, in the present invention, as described above, the spring force of the spring 21 acts before the lift or only before the lift and at the early stage of the lift. As for the relationship between the roller 5 of the rocker arm 2 and the cam 6, it works only when the roller 5 is in contact with the base circle of the cam 6, or only when the base circle and the lift are in the initial stage, and otherwise the spring force. Does not or hardly acts on the stem head 9a of the valve 9.

As a result, as shown in FIG. 4, when the valve 9 is lifted, no spring force is applied by the spring 21 and the valve 9 is prevented from jumping up.

FIG. 6 shows another embodiment of the present invention. The valve mechanism shown in FIG. 6 uses a compression spring 26 in place of the spring 21. The support portion 20 has a hole 20a vertically above the rocker arm 3 in the vicinity of the tip 3b of the rocker arm 3. The cylinder 24 is bored, and the cylinder 24 is fitted in the hole 20a with the opening end facing downward. Further, the cylinder 25 is axially slidable in the cylinder 24 with the closed end facing downward. And a compression spring 26 is contracted between the cylinders 24 and 25. A projection 25a that projects from the center of the closed end surface of the cylinder 25 is pressed against a boss 3d that projects near the tip 3b of the upper surface 3c of the rocker arm 3. A snap ring 32 is provided as a stopper inside the open end of the cylinder 24.

Therefore, the cylinder 25 applies a pressing force in the clockwise direction in the figure to the rocker arms 3 and 4 by the spring force of the spring 26, but when the rocker arms 3 and 4 slightly rotate, the cylinder 24 moves. The lower end hits the snap ring 32 and cannot be further lowered, so that the spring force is not applied to the rocker arms 3 and 4. That is, as shown in FIG. 7, the spring force acts only at the initial stage of the lift of the valve 9, and the rest is not exerted.

Therefore, as in the previous embodiment, the rocker arms 3 and 4 are prevented from jumping up in the descending section of the cam 6 of the rocker arms 3 and 4, and the rocker shaft 1 is prevented from being rotated by the rocker arm 2 and is As shown in FIG. 8, when the valve 9 is driven, no extra biasing force is applied to the valve 9, so that the valve 9 is prevented from jumping up and the desired valve operating characteristic is obtained.

FIG. 9 shows another example in which a torsion spring is used. That is, the torsion spring 33 is fitted to the base end 3a of the rocker arm 3 to fix one end thereof, and the other end is hooked on the fixed support portion 20. When the torsion spring 33 is used, not only does the spring force gradually decrease in accordance with the lift amount of the valve 9 as shown by a in FIG. 10, but also the lift amount of the valve 9 as shown by b in the drawing. Accordingly, the spring force for pressing the valve 9 gradually disappears, and then the spring force in the opposite direction, that is, the spring force in the same direction as the valve spring 31 can be applied. Therefore, when the valve 9 is opened and closed, the valve 9 is prevented from jumping up more reliably.

A tension spring or the like can be used as the spring 21 in addition to the above, and a member other than the spring can also be used as the biasing means. In the present embodiment, the description has been given of the case where it is applied to the valve operating mechanism of the variable cylinder engine, but the present invention is not limited to this, and the valve operating in which the valve timing can be changed according to the operating state of the engine It can also be applied to a mechanism.

[0023]

[Effect of the device]

 As described above, according to the present invention, the first rocker arm having the tip abutting on the cam and the base end rotatably supported by the rocker shaft, and the rocker shaft and the base end of the rocker arm each have a diametrical direction. Of the engine equipped with a piston that is fitted into a piston hole that is bored in the piston to connect or disconnect them, and a second rocker arm whose base end is fixed to the rocker shaft and whose tip contacts the stem head of the valve. In the valve mechanism, an urging means is provided which is interposed between the tip end side of the second rocker arm and a portion irrelevant to the movement of the valve operating mechanism and presses the tip end of the second rocker arm to the stem head. The structure prevents the piston holes of the rocker shaft and the first rocker arm from slipping in the base circle section of the cam when the cylinder is inactive, and the piston of the rocker shaft is The piston drawn inside can be easily fitted into the piston hole of the first rocker arm, and it will be possible to return from cylinder deactivation operation to full cylinder operation or change valve timing smoothly. There is an effect. Furthermore, since the urging means applies the urging force only before the valve is lifted or at the beginning of the lift, the valve does not jump up when opening or closing the valve, and there is no increase in friction. , It is not necessary to strengthen the valve spring.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a valve operating mechanism of an engine according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a diagram showing a relationship between a valve lift amount and a spring force.

FIG. 4 is a diagram showing a relationship between a valve lift amount and a force applied to a valve.

FIG. 5 is an explanatory diagram of a problem when the spring force is always applied.

FIG. 6 is a cross-sectional view of main parts of another embodiment.

FIG. 7 is a diagram showing a relationship between a valve lift amount and a spring force.

FIG. 8 is a diagram showing a relationship between a valve lift amount and a force applied to a valve.

FIG. 9 is a cross-sectional view of main parts of another embodiment.

FIG. 10 is a diagram showing a relationship between a valve lift amount and a spring force.

FIG. 11 is a partial cross-sectional view of a conventional engine valve mechanism.

FIG. 12 is a plan view of FIG. 11.

[Explanation of symbols]

 1 Rocker shaft 2, 3, 4 Rocker arm 5 Roller 6 Cam 9 Valve 20 Support part 21 Spring 26 Compression spring 31 Valve spring 32 Snap ring 33 Torsion spring

Claims (2)

[Scope of utility model registration request] 1. A first rocker arm having a distal end abutting on a cam and a proximal end rotatably supported on a rocker shaft, and piston holes diametrically formed at the proximal ends of the rocker shaft and the rocker arm, respectively. A second rocker arm having a base end fixed to the rocker shaft and a distal end abutting against a stem head of the valve.
Is provided between the tip end side of the rocker arm and a portion irrelevant to the movement of the valve operating mechanism, and biasing means for pushing the tip end of the second rocker arm to the stem head is provided. An engine valve operating mechanism characterized in that the urging force is applied only before the lift or from the front of the lift to the initial stage of the lift. 2. The valve operating mechanism for an engine according to claim 1, wherein the urging means is such that the urging force thereof gradually decreases with the lift of the valve.