JPH01116208A - Valve system for engine - Google Patents

Abstract

PURPOSE:To improve reliability of the operation of rocker arm switching mechanisms by forming a connecting passage for connecting a pressure chamber to the outside in a select pin which engages with/disengages from rocker arms adjacent to each other. CONSTITUTION:Rocker arm switching mechanisms 30A, 30B are provided between rocker arms 9, 10 adjacent to each other. A connecting passage 40 for connecting a pressure chamber 20 to the outside is formed in a select pin 25 which engages with/disengages from rocker arms 9, 10 by hydraulic pressure in the pressure chamber 20. At the time of low hydraulic pressure, the connecting passage 40 is opened to continuously carry out air bleeding operation. At the time of high hydraulic pressure, the connecting passage 40 is closed to maintain hydraulic pressure in the pressure chamber 20. Accordingly, reliability of the operation of the rocker arm switching mechanisms can be improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a valve train for an engine.

(Prior art) There has traditionally been a demand for engines to obtain better output performance throughout the entire speed range by changing the operating characteristics of the intake and exhaust valves at low speeds and high speeds. It is known that two types of cams are provided, a cam and a high-speed cam, and these two cams are selectively used depending on the engine speed (for example, Utility Model No. 61-58
(See Publication No. 605).

By the way, this type of valve train, as disclosed in the above-mentioned known example, switches between a low-speed cam and a high-speed cam by engaging a low-speed rocker arm that engages the low-speed cam and a high-speed cam. This is done by disposing a select pin that moves in and out in response to hydraulic pressure between the high-speed rocker arm and causing the low-speed rocker arm and the high-speed rocker arm to integrally engage or separate as the select pin moves in and out. It is configured as follows. Specifically, when the engine is running at low speeds, the hydraulic pressure supplied to the pressure chamber is low, and the select pin is positioned at a position where the high-speed rocker arm and the low-speed rocker arm are separated by the spring force of the return spring. At high speeds, the hydraulic pressure becomes high and the select pin moves against the spring force of the return spring to integrally connect the two-ended hook arms.

In this case, if air is mixed in the hydraulic oil in the pressure chamber formed on the pressure receiving surface side of the select pin, problems such as a delay in the cam switching action or even difficulty in the switching action itself may occur. Since this will occur, it is necessary to exhaust the air inside the pressure chamber to the outside.

As a specific means for this, conventionally, a communication passage that communicates the pressure chamber with the outside is formed in the cylinder into which the select pin is inserted, and hydraulic oil is continuously supplied from this communication passage while the engine is operating. The structure was such that air was removed by discharging a portion of the air to the outside.

However, if the communication passage is always open in this way and a part of the hydraulic oil is continuously discharged from the pressure chamber to the outside while the engine is running, then at low oil pressure and low speed, the communication passage is Since the amount of oil discharged is relatively small, there is almost no problem, but at high speeds when the oil pressure is high, (1) The amount of 411 discharged from the communication passage increases, resulting in a shortage of oil and the oil pressure in the pressure chamber. (2) High pressure from the communication passage may be easily changed due to fluctuations in engine speed, and in some cases, it may become difficult to maintain the connection between the high-speed rocker arm and the low-speed rocker arm using the select pin. Since a large amount of hydraulic oil is spewed out, problems may arise such as the spouted hydraulic oil hitting the inner surface of the head cover directly and causing noise, or the amount of blow-by gas increasing due to the increased amount of scattered oil. .

Note that one possible way to suppress the occurrence of such problems is to reduce the diameter of the communication passage, but the diameter of this communication passage needs to be relatively large from the perspective of avoiding clogging due to foreign matter. There is naturally a limit to the effect of reducing the diameter of the communicating path.

(Object of the Invention) The present invention is intended to solve the problems pointed out in the above-mentioned section of the prior art. By controlling the discharge of hydraulic oil from the pressure chamber in the valve train of an engine that has been designed to operate, the operation of the rocker arm switching mechanism is ensured, increasing its operational reliability, and reducing engine noise and blow-by gas. The purpose is to suppress this as much as possible.

(Means for Achieving the Object) As a means for achieving the above object, the present invention provides an engine in which the valve operating characteristics of an intake valve or an exhaust valve are changed by engaging and disengaging adjacent rocker arms. In this valve operating system, the rocker arms are fitted into the cylinder so as to be movable 1-1 and can be slidably displaced in response to the hydraulic pressure introduced into a pressure chamber formed at one end of the cylinder. At times, it is located at a first position spanning between the rocker arms and integrally connecting them, and when the AI+pressure is low, a second position is located at either side of the rocker arm and allows relative displacement in these rocking force directions. The cylinder or the select pin has a select pin that is selectively positioned at each position, and the cylinder or the select pin forms a communication passage that communicates the pressure chamber with the outside, and the select pin is configured to connect the communication passage to the first position. When the select pin is set to the second position, the select pin is closed, and when the select pin is set to the second position, the select pin is opened.

(Function) In the present invention, by the above-mentioned means, (1) When the oil pressure supplied to the pressure chamber is low, the select pin is set to the second position and the communication passage is open; A part of the hydraulic oil is discharged to the outside through the pressure chamber, and the air in the pressure chamber is continuously vented. (2) When the hydraulic pressure supplied to the pressure chamber is high, the communication passage is blocked. Since the discharge of hydraulic fluid through the communication passage is prevented, the 411 pressure in the pressure chamber is maintained at a hydraulic pressure sufficient to always hold the select pin in the first position, and the rocker arms are mutually connected by the select pin. Effects such as stably securing the bonding state between the two can be obtained.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 3.

(First Embodiment) FIG. 1 shows the main parts of an automobile Mitsui type (intake valve, displacement valve) OHC engine equipped with a valve train according to a first embodiment of the present invention. In the figure, 1 is the cylinder head, 2 is the intake valve (two arranged along the axial direction of the camshaft 4), and 3 is the exhaust valve.These two intake valves 2 and one exhaust valve 3 are They are arranged on both sides of the camshaft 4.

As shown in FIG. 2, the camshaft 4 has four valve operating cams in its axial direction, that is, a first low-speed cam 5 and a second low-speed cam 80 located at both ends in the axial direction. Moreover, the first
It has four valve operating cams: a high speed cam 7 located closer to the low speed cam 5 and an exhaust valve cam 8 located closer to the second low speed cam 6.

Of these four cams, the first low speed cam 5, the second low speed cam 6, and the high speed cam 7 serve as intake valve driving cams.

As shown in FIG. 5, one end 11a of an exhaust rocker arm 11 swingably supported by an exhaust rocker shaft 16 is brought into contact with the exhaust valve cam 8 of the camshaft 4. Further, the upper end of the stem of the exhaust valve 3 is brought into contact with the other end 11b of the exhaust rocker arm 11 via an adjuster 14.

On the other hand, the three intake valve cams 5.6 of the camshaft 4
．． 7 are engaged with intake valve arms 9, 9, and 10, respectively, as will be described later.

The low-speed rocker arm 9 is swingably supported by an intake rocker shaft 15 whose interior is a hydraulic oil supply passage 17, and a force 120-ra 12 is provided at the other end 9b. This low-speed rocker arm 9 connects a high-speed rocker arm 10 (described later) to an intake rocker shaft 15.
One cam roller 12 is provided on both sides of the camshaft 4 in the axial direction, and the cam roller 12 of one low-speed rocker arm 9 is connected to the first low-speed cam 5 of the camshaft 4, and the other low-speed rocker arm 9 is connected to the first low-speed cam 5 of the camshaft 4. Arm 9 cam roller! 2 are brought into contact with the second low-speed cam 6, respectively.

The high-speed rocker arm 10 is swingably supported by the intake rocker shaft 15 while being located between the pair of low-speed rocker arms 9.9. Unlike the low-speed rocker arm 9, this high-speed rocker arm 10 does not have an end that engages with the intake valve 2, and only has a cam roller 13 at one end that abuts the high-speed cam 7 of the camshaft 4. are doing. Therefore, the low-speed rocker arm 9 can drive the intake valve 2 by itself, but the high-speed rocker arm 10 cannot drive the intake valve 2 by itself. For this reason, two rocker arm switching mechanisms 30A and 30I3, which will be described later, are provided between the two low-speed rocker arms 9 and the high-speed rocker arms IO, respectively, to integrally connect this rain sound as necessary. 1 has been installed. Note that these two rocker arm switching mechanisms 30A, 30) 3 have the same configuration,
Therefore, here, the configuration will be explained using the first rocker arm switching mechanism 30A as an example, and its operation will be explained using both the first rocker arm switching mechanism 30Δ and the second rocker arm switching mechanism 30B. I'll give an explanation. Also, for convenience of explaining this operation, two rocker arm switching mechanisms 30A and 30 are shown in FIG.
13, the first rocker arm switching mechanism 30A is shown in a low speed state, and the second rocker arm switching mechanism 3013 is shown in a high speed state.

The rocker arm switching mechanism 30A includes a deep-hole-shaped low-speed cylinder 31 provided on the low-speed rocker arm 9 side, and a low-speed cylinder 3 provided on the high-speed rocker arm 10 side.
A high-speed cylinder 32 in the form of a deep hole with a stopper 26 provided coaxially with the cylinder 1, and a select pin 25 fitted into these two cylinders so as to be slidable in the axial direction (direction of arrows A-B). have.

The select pin 25 is composed of a short shaft having a recess 28 formed on one end surface 25a in the axial direction and a spring receiver 29 formed on the other end surface 25b. 28 bottom and spring receiver 2
Communication paths 40, 40, . . . are formed to communicate with the end surface 25b on the 9 side. The select pin 25 is connected to the cylinder 31 and the cylinder 3 with the spring receiver 29 facing the cylinder 31 side and always being urged toward the cylinder 3'2 side by the return spring 27 provided on the cylinder 31 side. In this case, the axial length of this select pin 25 is the same as that of these cylinders 31.
The relative relationship with 32 is set as follows.

That is, the axial length of the select pin is different from the other end surface 25 like the select pin 25 of the second rocker arm switching mechanism 30B.
When b is in contact with the bottom 31a of the cylinder 31 (in the following description, the position of the select pin in this state will be referred to as the first position), the select pin is placed astride both the cylinder 31 and the cylinder 32; against the first
One end surface 25a of the select pin 25 of the rocker arm switching mechanism 30A is in contact with the stopper 26.
(In the following description, the position of the select pin in this state will be referred to as a second position.) The select pin is set relative to the cylinder 31, 32 so that it is located only on the cylinder 32 side.

Therefore, when the select pin 25 is set at the first position, the high speed rocker arm 10 and the low speed rocker arm 9 are integrally connected by the select pin 25, and both of them are connected to the intake rocker arm 15. It oscillates as a unit around the center.

Further, in this state, the communication passages 40, 40, . . . formed in the select pin 25 are closed by the bottom surface 31a of the cylinder 31.

On the other hand, when the select pin 25 is set at the second position, the select pin 25 is not engaged with the low speed rocker arm 9, and the low speed rocker arm 9 and the high speed rocker arm 10 are not engaged with each other. are made to swing separately. Furthermore, in this state, the communicating passages 40° 40 are open since the end surface 25b and the bottom surface 31a of the cylinder 31 are separated from each other.

Note that this pressure chamber 20 is connected to a hydraulic oil supply passage 17 formed in the intake rocker shaft 15 via a pressure chamber 22.
is communicated with. Furthermore, this hydraulic oil supply passage 17 communicates with a hydraulic pressure source via a hydraulic control means (not shown). Note that this hydraulic control means is connected to the hydraulic oil supply passage 17.
The pressure of the hydraulic oil supplied to the side is set in two levels, high and low, depending on the engine speed; specifically, high pressure is set at high speeds, and low pressure is set at low speeds. Furthermore, between the first low-speed cam 5 and the high-speed cam 7 of the camshaft 4, the cam profile is set such that the cam lift of the high-speed cam 7 is larger than that of the first low-speed cam 5. is set relatively.

Rocker arm switching mechanism 30A configured as described above,
30B, the hydraulic pressure supplied to the pressure chamber 20 is low when the engine is running at low speed.
The select pin 25 is moved to the second position due to the difference between the spring force of the return spring 27 and the pressure acting on the select pin 25.
It is positioned at the position of Therefore, the low-speed rocker arm 9 and the high-speed rocker arm 10 are not connected to each other, and the rotation of the camshaft 4 causes the low-speed rocker arm 9 to swing, and the intake valve 2 is connected to the first low-speed cam 5. It opens and closes under the action of the cam.

In addition, in this state, the communication path 40.4 of the select pin 25
0... are opened, a part of the hydraulic oil introduced into the pressure chamber 20 is discharged to the outside through the communication passages 40, 40..., but at the same time, the pressure chamber 20 The air accumulated inside is discharged to the outside together with the hydraulic oil (achieving air bleed action).

This ensures accurate and quick operation of the rocker arm switching mechanisms 30A, 30B.

Furthermore, in this case, some of the hydraulic oil is discharged to the outside from the communication passages 40, 40, etc., so the hydraulic pressure in the pressure chamber 20 becomes low. The select pin 25 is urged toward the stopper 26 by force, and the drop in the oil pressure in the pressure chamber 20 does not impede the operation of the select pin 25; on the contrary, it acts favorably. Also, the communication path 40.40・
・Since the pressure of the hydraulic oil discharged from is low and there is little oil soaking, it may hit the inside of the head cover and generate a loud impact sound, or the increased amount of splashed oil may generate more blow-by gas. The occurrence of defects is prevented.

On the other hand, when the engine speed increases from this state and moves to the high speed side (1T), high pressure oil pressure is supplied to the pressure chamber 20, and the select pin 25 receives this oil pressure and moves in the direction of the arrow, and the low speed rocker arm 9 and the high speed cylinder 32 of the high speed rocker arm 10. Therefore, the low-speed rocker arm 9 and the high-speed rocker arm 10 are integrated, but in this case, since the valve lift of the high-speed cam 7 is relatively larger than the valve lift of the first low-speed cam 5, The low-speed rocker arm 9 and the high-speed rocker arm IO swing together in response to the cam action Ill of the high-speed cam 7, thereby opening and closing the intake valve 2. This allows different valve characteristics to be obtained at low speeds and at high speeds.

In this case, this first position must be maintained during high-speed operation of the engine, but even during such high-speed operation, a portion of the hydraulic oil is continuously drained from the communication passage, as in conventional valve train systems. As mentioned above, if the select pin 25 is kept in the first position, the oil pressure in the pressure chamber 20 will drop significantly due to a slight decrease in engine speed, and in some cases, it may become difficult to hold the select pin 25 in the first position. .

However, in this embodiment, when the select pin 25 is set at the first position as described above, the communication passages 40.40 are closed.
From the point where the discharge of hydraulic oil through . Be it. Therefore, the operation of the rocker arm switching mechanism is ensured, and its operational reliability is improved.

(Second Embodiment) FIG. 3 shows the main parts of a valve train according to a second embodiment of the present invention. This rocker arm switching mechanism has a rocker arm switching mechanism 30 having a structure similar to that of the first embodiment.
A, 30B, and therefore, it goes without saying that the same operation and effect as the first valve train can be obtained, but in this embodiment, the structure of the communication passage 40 is further devised. Due to Zuko, in addition to the above actions and effects, [! The lever shaft switching action can be performed quickly and reliably. Hereinafter, only the structure and function of this communication passage 40 will be described in detail, and other members will be designated with reference numerals corresponding to the respective members in FIG. 2, and their explanation will be omitted.

The select pin 25 is integrally formed with a short shaft having a recess 28 and a spring receiver 29 formed on both end surfaces 25a and 25b. The select pin 25 has a circumferential groove 42 formed on its outer circumferential surface, and the circumferential groove 42 and the recess 28 are communicated with each other through a plurality of diagonal holes 41 .

Furthermore, when the select pin 25 on the peripheral wall of the cylinder 31 is set at the second position (the position of the select pin 25 on the first rocker arm switching mode +1I30A side), the circumferential groove 42 of the select pin 25 corresponds to The position is
A through hole 43 is formed, and the pressure chamber 20 is formed through this diagonal hole 4.
1, the circumference 'fIt42, and the through hole 43 to communicate with the outside. In this embodiment, this diagonal hole 4! A series of passages consisting of the circumferential groove 42 and the through hole 43 corresponds to the communication passage in the claims.

Further, this communication path 40 is connected to the state where the select pin 25 is set at the first position (second rocker arm switching device +N
30B select pin 25 position), the circumference i1
The I42 and the through hole 43 are relatively displaced in the axial direction so as to be out of communication with each other, and the circumferential groove 42 faces the inner circumferential surface of the cylinder 32, thereby being closed. Therefore, in this state, the pressure chamber 20 is in a closed state.

By configuring the communication passage 40 in this way, the select pin 25 is set to the second position when the engine is operating at low speed, and air is vented through the communication passage 40.
During the transition period when switching from low speed to high speed, the communication passage 40 is closed immediately after the select pin 25 starts moving, so the oil pressure in the pressure chamber 20 increases rapidly, and the select pin 25 quickly and reliably moves to the first position. Since the communication passage 40 is closed during high-speed operation, the pressure chamber 20
The hydraulic pressure inside the select pin 25 is maintained at an appropriate pressure at all times, ensuring that the select pin 25 is held in the first position.

In the above embodiment, the selection pin is used to engage and disengage two rocker arms that are swung by different cams. A rocker arm, such as a valve train, that controls the operation and stop of the intake valve or exhaust valve by engaging the other rocker arm with the intake valve or exhaust valve, and then engaging and disengaging the double-ended lock arm with a select pin. The present invention can also be applied to an engine valve operating system in which the valve operating characteristics of an intake valve or an exhaust valve are changed by engaging and disengaging between the intake valve and the exhaust valve using a hydraulically operated select pin.

(Effects of the Invention) The present invention provides an engine valve operating system for changing the valve operating characteristics of an intake valve or an exhaust valve by engaging and disengaging adjacent rocker arms. A first position where the rocker arm is freely fitted and can be slid and displaced in response to the hydraulic pressure introduced into a pressure chamber formed at one end thereof, and when the hydraulic pressure is high, it straddles between the rocker arms and integrally connects both. In addition, when the oil pressure is low, the rocker arm has a select pin that is selectively positioned at a second position that is located on either side of the rocker arm and allows relative displacement in the rocking direction. A communication path is formed in the cylinder or a select pin that communicates the pressure chamber with the outside, and the communication path is closed when the select pin is set at a first position, and when the select pin is set at a second position. It is characterized in that it is configured so that it is opened when it is set to .

Therefore, according to the engine valve train of the present invention, since the air bleeding action through the communication passage is performed only at low oil pressure and not at high oil pressure, (+) Hydraulic oil discharged from the (2°) communication path, which maintains proper oil pressure at all times and ensures stable connection between the rocker arms by the select pin, improving the operational reliability of the valve gear. Since the pressure is low and the amount of oil is small, collision of this discharged oil with the inner surface of the head cover is suppressed, engine noise due to collision sound is reduced as much as possible, and the amount of scattered oil is reduced as much as possible. Effects such as suppressing blow-by gas generation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of a valve train according to a first embodiment of the present invention, FIG. 2 is an enlarged view of the section ■ in FIG. 1, and FIG. FIG. 3 is a cross-sectional view of the main parts of the valve device. ■...Cylinder head 2...Intake valve 3...Exhaust valve 4...Camshaft 5.6...Cam for low speed 7...For high speed Cam 8...Exhaust valve cam 9...Low speed rocker arm lO...High speed rocker arm 12.13...Cam roller I4...Adjuster 15, 16...Rocker Shaft 17... Hydraulic oil supply passage 20... Pressure chamber 22... Pressure chamber inlet 25... Select pin 27... Return spring 30^, 30B... Rocker arm switching mechanism 31 .3
2 ・Children・Cylinder 40・・・Communication path

Claims (1)

[Claims] 1. In an engine valve operating system that changes the valve operating characteristics of an intake valve or an exhaust valve by engaging and disengaging adjacent rocker arms, a valve that is slidably inserted into a cylinder between the rocker arms and that It can be slid and displaced in accordance with the hydraulic pressure introduced into a pressure chamber formed on one end side, and when the hydraulic pressure is high, it is in the first position where it straddles between the rocker arms and integrally connects the two, and when the hydraulic pressure is low, the rocker arm is in the first position where it is integrally connected. A select pin is provided on either side of the arm and selectively positioned at a second position that allows relative displacement in these swing directions, and the cylinder or the select pin is provided with the pressure chamber. A communication path communicating with the outside is formed, and the communication path is closed when the select pin is set in the first position and is open when the select pin is set in the second position. A valve train for an engine, characterized in that it is configured as follows.