JP2821253B2 - Engine Valve Actuator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve operating device for an engine, and more particularly to a device for switching a valve lift characteristic according to operating conditions of an engine.

(Prior Art) Conventionally, in order to achieve both a torque at low to medium speed operation and an increase in output at high speed operation, the lift characteristics of the intake valve or the exhaust valve are made different depending on the operation state, whereby the timing of intake and exhaust or It is known to control the amount of intake and exhaust (see, for example, JP-A-63-167016 and JP-A-63-57805).

To explain this, a rocker arm whose swinging tip contacts the valve and a sub rocker arm adjacent to one side of the rocker arm and having no contact portion with the valve are swingably supported by a common rocker shaft, A low-speed cam is slid on the rocker arm, and a high-speed cam having a profile in which the valve opening angle or the valve lift is larger than that of the low-speed cam is slid on the sub rocker arm.

In a direction parallel to the rocker shaft at a rocking portion separated from the rocker shaft by a predetermined distance, two rocker arms are connected by a pin that responds to the operating oil pressure is fitted into or removed from the fitting hole. Or the bond is broken.

(Problems to be Solved by the Invention) In such a conventional apparatus, two sub rocker arms are provided for one rocker arm so as to be relatively displaceable in order to switch three cams for one valve. In this case, a connecting pin and a hydraulic passage for driving the connecting pin are required corresponding to the two sub rocker arms. In particular, by interposing two return springs for biasing the pin to a predetermined sliding position, the structure of the rocker arm can be improved. The complexity and size increase have made it difficult to switch between three or more cams.

It is an object of the present invention to provide a valve operating device capable of switching between three cams by focusing on such a conventional problem and simplifying a connection structure between rocker arms.

(Means for Solving the Problems) According to the present invention, three cams having different profiles are provided, and each cam is provided to a rocker arm that opens and closes an intake valve or an exhaust valve by following a cam having a relatively small profile. , Two sub-rocker arms that are driven relative to each other are connected so as to be relatively displaceable, and a plurality of pins that are slidably fitted across the rocker arm and each sub-rocker arm are interposed in series,
A single return spring, which holds each pin in an unconstrained position where relative displacement of each sub rocker arm with respect to the rocker arm is possible, is interposed between the pins located at the center, and each pin is positioned against the rocker arm against the return spring. Two hydraulic passages are provided for sliding to a restraining position for locking the relative displacement of each sub rocker arm.

(Operation) In a state where the pins corresponding to the two sub rocker arms are both held at the unconstrained positions by the urging force of the return spring, each sub rocker arm driven by each cam is displaced relative to the rocker arm and the rocker arm moves. The rocker arm opens and closes the valve according to the profile of the directly driven cam without obstruction.

When the pin corresponding to one of the sub rocker arms is slid to the restraining position for restraining the sub rocker arm while compressing the return spring by the operating oil pressure guided from the hydraulic passage, the rocker arm swings integrally with the sub rocker arm. The sub rocker arm moves and opens and closes the valve according to the profile of the cam that is driven by the sub rocker arm, and the lift amount or the valve opening period of the valve increases. At this time, the pin corresponding to the other sub rocker arm is held at the non-restrained position by the biasing force of the return spring, the other sub rocker arm is displaced relative to the rocker arm and does not hinder the movement of the rocker arm, and the rocker arm is Emits from a relatively small cam in the profile.

When the sub-rocker arms involved in the opening and closing operations of the valve are switched with each other, one of the hydraulic passages is depressurized while the other hydraulic passage is pressurized. Since the return spring is compressed to increase its urging force, the speed at which the other pin slides to the unconstrained position is increased, and the switching response of the cam is improved.

Since a plurality of pins connecting the respective sub rocker arms to the rocker arm are urged by a common return spring, the structure of the rocker arm is simplified and the size is reduced.

(Embodiment) FIGS. 1, 2, 3, and 4 show two valves having the same function for one cylinder (either an intake valve or an exhaust valve. An embodiment in which the present invention is applied to an engine provided with (hereinafter referred to as) is shown.

To explain this, each cylinder has two intake valves 9.
, A single rocker arm 1 is provided. A base end of the rocker arm 1 is swingably supported by a cylinder head 15 via a rocker shaft 12 common to each cylinder, and a front end of the rocker arm 1 contacts a stem top of each intake valve 9 via a shim 10. Is integrally formed. The swing of the rocker arm 1 pushes down the two intake valves 9 while compressing the valve spring 18 to open the intake port 19.

Needle bearing on shaft 13 for rocker arm 1
The roller follower 4 is rotatably connected via 14, and the roller follower 4 is brought into contact with the partial cam 21 to swing the rocker arm 1.

The rocker arm 1 is formed in a substantially rectangular shape in a plan view, and two sub rocker arms 2 and 3 are provided alongside the roller follower 4. The base ends of the sub rocker arms 2 and 3 are connected to the rocker arm 1 via a rocker shaft 16 so as to be relatively rotatable.

Each of the sub rocker arms 2 and 3 does not have a portion that comes into contact with the intake valve 9, and has a low-speed cam 22 and a high-speed cam at its tip.
The cam follower portions 2A and 3A that are in sliding contact with 23 are formed to project in an arc shape in cross section, and the cam follower portions 2A and 3A
The lost motion spring 7 that presses the cams 22 and 23 is interposed. Note that a cylindrical lifter 8 slidably fitted to the rocker arm 1 is interposed between each lost motion spring 7 and each sub rocker arm 2, 3.

As shown in FIG. 5, the rocker arm 1 and the sub-rocker arms 2, 3 are separated from the rocker shaft 12 by a predetermined distance so that the relative displacement of each rocker arm 2, 3 with respect to the rocker arm 1 can be locked. At the swinging portion, the six pins 31 to 36 extend in a direction parallel to the rocker shaft 12.
Are slidably provided.

The sub rocker arms 2 and 3 are formed with respective fitting holes 42 and 43, while the rocker arm 1 is formed with three fitting holes 44, 45 and 46 having the same diameter so as to sandwich both the fitting holes 42 and 43. Is formed. Roller follower 4 and each sub rocker arm 2,
Reference numeral 3 denotes a rotation angle range in contact with the base circle portions of the cams 21, 22, and 23, and the fitting holes 42 to 46 are formed so as to be aligned on the same axis.

The pin 31 is slidably fitted over the fitting hole 44 of the rocker arm 1 and the fitting hole 42 of the sub rocker arm 2. This pin
The pin 32 abutting on one end of the slide 31 is slidably fitted over the fitting hole 42 of the sub rocker arm 2 and the fitting hole 45 of the rocker arm 1.

A pin 33 in contact with one end of the pin 32 is slidably fitted into a fitting hole 45 of the rocker arm 1, and a return spring 37 is seated on one end of the pin 33,
Due to the urging force of the pin 37, the pin 31 comes into contact with the stopper 47 and fits in the fitting hole 44 of the rocker arm 1, and the pin 32 is held in a non-constrained position where it fits in the fitting hole 42 of the sub rocker arm 2.

The pin 34 seated at the other end of the return spring 37 has a fitting hole 45 of the rocker arm 1 and a fitting hole 43 of the sub rocker arm 3.
To be able to fit over. The pin 35 abutting on one end of the pin 34 slides so as to fit between the fitting hole 43 of the sub rocker arm 3 and the fitting hole 46 of the rocker arm 1. The pin 36 in contact with one end of the pin 35 slides so as to fit over the fitting hole 46 of the rocker arm 1 and the fitting hole 43 of the sub rocker arm 3. The pin 36 fits into the fitting hole 46 by the urging force of the return spring 37, and the pin 35 is held at a non-constrained position where the pin 35 fits in the fitting hole 43 of the sub rocker arm 3.

The end of the fitting hole 44 opened at the hydraulic passage 39, each pin 31, 32, 33 by the hydraulic force P ₂ which now guided to slide restraint position against the return spring 37.

The end of the fitting hole 46 hydraulic passage 40 is opened, the pin 34, 35 and 36 by hydraulic pressure P ₁ that is now guided slides the arresting position against the return spring 37.

The hydraulic passages 39 and 40 are respectively provided through the rocker arm 1 and the rocker shaft 12, and the discharge hydraulic pressure of an oil pump (not shown) is guided through a control valve.

A stopper 49 protrudes from the center of the fitting 45 of the rocker arm 1 on which the return spring 37 is interposed.
3 and 34 contact this stopper 49,
31, 32, 33 and the stroke L ₂ of, so as to regulate the stroke L ₁ of each pin 34, 35, 36.

The operating oil pressures P ₁ and P ₂ guided from the hydraulic passages 40 and 39 are set to be larger than the spring load of the return spring 37 when it is most contracted. That is, if k is a spring constant, P ₁ > P ₂ > k
(L ₁ + L ₂ ) is set.

The control unit that electronically controls the operation of the hydraulic control valve inputs the engine rotation signal, cooling water temperature signal, hydraulic oil temperature signal, supercharging pressure signal of intake air by the supercharger, slot valve opening signal, etc. The cams 21, 22, 23
Switch smoothly.

Each of the cams 21, 22, and 23 is integrally formed on a common camshaft 11, and has different shapes (sizes) so as to satisfy the valve lift characteristics required when the engine is in a partial state, when the engine is under a high load, and when the engine is at a high speed. (Including similar forms with different
Is formed. Here, the valve lift and the valve opening period are both increased in the order of the partial cam 21, the low speed cam 22, and the high speed cam 23. As a result, the smallest lift amount,
While using the cam 21 during the small valve opening period to improve the fuel efficiency by using the partial load and the idle operation, the medium lift amount during the high load low speed operation and the high load high speed operation using the low speed cam 22 during the medium valve opening period are used. At times, the cam is switched to the high-speed cam 23 with a large lift amount and a large valve opening period to achieve high output.

 Next, the operation will be described.

During the partial operation of the engine, the operating oil pressure in each of the hydraulic passages 39 and 40 is kept at the minimum value, and as shown in FIG. Of the rocker arm 1
Does not hinder the movement of As a result, the rocker arm 1 swings according to the profile of the partial cam 21 and drives each intake valve 9 to open and close.

During low-speed high-load operation of the engine, the working oil pressure derived from the hydraulic passage 39 is raised to a predetermined value P _2, as shown in FIG. 6, the return spring 37 the pin 31 while compressing the,
33 slides and is held at the restraining position where it fits between the sub rocker arm 2 and the rocker arm 1. On the other hand, the pins 34, 35,
36 is held in the non-restrained position by the urging force of the return spring 37 and does not hinder the movement of the rocker arm 1, whereby the rocker arm 1 swings integrally with the sub-rocker arm 2, and It swings according to the profile of the cam 22, and drives each intake valve 9 to open and close. At this time, the roller follower 4 is floating from the low speed cam 21.

During high speed and high load operation of the engine, hydraulic pressure P ₁ to be guided to the hydraulic passage 40 is higher than hydraulic pressure P ₂ derived from the hydraulic passage 39, as shown in FIG. 7, the return spring 37
The pins 31 to 36 move while compressing the sub-rocker arms 2 and 3 and are held at the restraining positions where the sub-rocker arms 2 and 3 swing together with the rocker arm 1. The rocker arm 1 swings through the sub rocker arm 3 according to the profile of the high-speed cam 23, and drives each intake valve 9 to open and close. At this time, the roller follower 4 and the sub rocker arm 2 are lifted from the respective cams 21 and 22.

The sub rocker arm 2, which is involved in opening and closing the intake valve 9,
When the pin 3 is switched, each of the pins 34, 35, and 36 slides to the restraining position, and the return spring 37 is compressed to increase its urging force. Speed of movement can be increased.

Conversely, as the operating oil pressure guided to the hydraulic passages 40 and 39 is sequentially reduced, the pins 31 to 36 move in the opposite direction to the above operation, and the sub rocker arms 2 and 3 with respect to the rocker arm 1 are moved.
Is released, and the cams 21, 22, and 23 are switched.

As described above, since the plurality of pins 31 to 36 connecting the respective sub rocker arms 2 and 3 to the rocker arm 1 are urged by the common return spring 37, the structure of the rocker arm 1 is simplified and the size is reduced. .

As shown in FIG. 8, the stopper does not protrude at the center of the fitting hole 45 of the rocker arm 1 in which the return spring 37 is interposed, and as shown in FIGS. Alternatively, with the sub rocker arm 3 restrained by the rocker arm 1, each pin 33, 3
4 may compress the return spring 37 so as to abut each other.

Also in this case, when switching from the sub rocker arm 3 involved in the opening and closing operation of the intake valve 9 to the sub rocker arm 2, one hydraulic passage 40 is depressurized and at the same time the other hydraulic passage 39
Is boosted, the pins 31, 32, and 33 slide to the restrained positions. At this time, the return spring 37 is compressed to increase its urging force, and the pins 33 and 34 contact each other and interlock with each other.
4,35,36 can be slid to the unconstrained position,
The switching response from 3 to the cam 22 is further improved.

(Effects of the Invention) According to the present invention, two sub rocker arms driven by respective cams are connected to a rocker arm that opens and closes an intake valve or an exhaust valve so as to be relatively displaceable, and slides across the rocker arm and each sub rocker arm. A single return spring is interposed between the centrally located pins, interleaving a plurality of pins that can be fitted in series and holding each pin in an unconstrained position that allows relative displacement of each sub rocker arm with respect to the rocker arm. And two hydraulic passages that slide each pin to a restraining position that locks the relative displacement of each sub rocker arm with respect to the rocker arm against the return spring are arranged, so the number of return springs is reduced and the structure is simplified. By using this technology, a valve actuator that switches the valve lift characteristics in three stages in a limited engine space will be put into practical use. In addition to being able to contribute to the reduction of the moving mass, it can respond to the high speed of the engine.

[Brief description of the drawings]

FIG. 1 is a plan view of a valve train showing an embodiment of the present invention, and FIG.
FIG. 3 is a cross-sectional view taken along the line BB in FIG. 3, FIG. 4 is a cross-sectional view taken along the line CC in FIG. 3, and FIG. FIG. 6 is a vertical sectional view taken along the line D-D in FIG.
FIG. 7 is a longitudinal sectional view showing the same operation. FIG. 8 is a longitudinal sectional view showing another embodiment, and FIGS. 9 and 10 are longitudinal sectional views showing the same operation. 1 ... rocker arm, 2,3 ... sub rocker arm, 7 ...
… Lost motion spring, 9 …… Intake valve, 12 ……
Rocker shaft, 16 …… Sub rocker shaft, 31-36…
... Pin, 37 ... Return spring, 39,40 ... Hydraulic passage.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Nakamura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Haruhiko Hoshino 2- Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Toru Kimura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Shoji Morita 1370 Onna, Atsugi-shi, Kanagawa Atsugi Unisia Co., Ltd. (72) Inventor Seinosuke Hara 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Unisia Co., Ltd. (56) References JP-A-64-45911 (JP, A) JP-A-64-19103 (JP, A) JP-A-62-121809 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) F01L 13/00 301 F01L 13/00 302

Claims (1)

(57) [Claims] The present invention provides three cams having different profiles, and a rocker arm for driving an intake valve or an exhaust valve to open or close by a cam having a relatively small profile. A plurality of pins that are connected to be relatively displaceable and that are slidably fitted across the rocker arm and each sub rocker arm are interposed in series,
A single return spring, which holds each pin in an unconstrained position where relative displacement of each sub rocker arm with respect to the rocker arm is possible, is interposed between the pins located at the center, and each pin is positioned against the rocker arm against the return spring. A valve operating device for an engine, comprising two hydraulic passages slid to a restraining position for locking the relative displacement of each sub rocker arm.