JPS59103912A - Intake/exhaust valve driving apparatus for internal- combustion engine - Google Patents

Abstract

PURPOSE:To vary the timing or the lift of an intake/exhaust valve by a small driving force, by varying the tilt of a level for supporting the swing fulcrum of a locker arm by controlling the feeding of oil into a hydraulic actuator. CONSTITUTION:The back surface of a locker arm is attached onto a lever whose tilt angle is varied according to the degree of extension and contraction of a hydraulic actuator 25, and the timing or the lift of an intake/exhaust valve is varied by shifting the swing fulcrum of the looker arm through the above-described extension and contraction. The degree of extension and contraction of the hydraulic actuator 25 depends onto the amount of oil feed which is controlled by the superposition of an oil hole 36 and a triangular oil-pressure feeding passage 37 formed on a sleeve 28 which is controlled by a control rack 26. Therefore, the actuator can be extended in the suspension time of each valve, and the valve can be controlled by a small driving force.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake/exhaust valve drive device for an internal combustion engine that variably controls the opening/closing timing of intake/exhaust valves and the valve lift amount in accordance with operating conditions.

Various intake and exhaust valve drive devices have been proposed in the past, which control the opening/closing timing and valve lift of the intake and exhaust valves according to the engine operating conditions so as to always achieve optimum pulp overlap and fresh air filling efficiency. One such example is US Pat. No. 3,413.965, shown in FIG.

This valve drive device has one end in contact with the pulp drive cam 1,
The back surface 4 of the rocker arm 3 whose other end is fitted and supported by the stem end of the intake/exhaust valve 2 is curved, and the rocker arm 3 swings from side to side while the back surface 4 contacts the lever 5 as a fulcrum, thereby causing the cam to move. 1 is transmitted to the intake/exhaust valve 2, in particular, the upper bar 5 is rotatably supported at one end thereof, and its inclination is regulated by a control cam 6. ing. The control cam 6 is rotationally driven in an appropriate phase according to engine operating conditions by a drive mechanism such as a hydraulic actuator, thereby variably controlling the opening/closing timing and the orientation of the intake/exhaust valves 2. That is, for example, if the lever 5 is pushed down by a large amount by the control cam 6, the free end of the lever 5 and the rocker arm 3 are close to each other in the base circle state of the pulp drive cam 10, and therefore the intake and exhaust valves 2 are not opened. If the timing is earlier and the lever lift is large and the amount of depression by the control cam 6 is small, the free end of the lever 5 and the rocker arm 3 will Therefore, the opening timing of the intake and exhaust valves is delayed and the amount of valve lift becomes small.

However, in such a conventional valve drive device, when applied to a multi-cylinder engine with four or more cylinders, for example, one of the intake and exhaust ff2 is always lifted.
Pulp Spring 70 Strong Anti Crab 11ill
A large torque acts on the shaft 6a of the in-cam 6, and a large and powerful actuator is required to resist this force and rotate the shaft 6a. Therefore, for example, in an engine for own DJT, it is difficult to arrange a large actuator within a limited space, and on the other hand, there is also a problem in terms of responsiveness of control of the control cam 6. Moreover, the power loss and wear on the cam surface caused by driving the control cam 6 become large.

In view of the above-mentioned drawbacks of the conventional art, the present invention overcomes the above-mentioned conventional art by configuring the inclination of the levers to be individually controlled by hydraulic actuators whose expansion and contraction are regulated in accordance with the rotational position 1d of the control sleeve. The purpose is to solve shortcomings.

That is, the internal combustion clean intake/exhaust valve drive device according to the present invention includes a lub drive cam that rotates in synchronization with engine rotation;
A rocker arm whose one end abuts the pulp drive cam and whose other end is linked to the pulp stem, and a rocker arm support surface disposed approximately between 11 of the rocker arm and whose back surface comes into fulcrum contact with the tl lever. , a bracket that supports one end of this lever on the pulp side, and one wheel on the cam side of the lever to control the inclination of the lever, and expands and contracts by regulating the oil supply to the hydraulic chamber according to the rotational position of the control sleeve. The hydraulic actuator is regulated.

Hereinafter, a specific example, which is obvious, will be explained in detail based on the drawings.

FIG. 2 is a side view showing one part of the flow side of the present invention, in which 11 is a nokuru drive cam that rotates in synchronization with the rotation, 12 is an intake and exhaust valve, and 13 is a pulp spring. , 14 indicates a bracket fixed to the cylinder head 15 with a bolt 16. 17 indicates a bracket having one end 17a connected to the lubricant drive cam 11, and the other end 17b connected to the stem end 12b of the pulp stem 12a. It has a support shaft 18 that is rotatably inserted through the substantially center of the support shaft 18, and the back surface 1 is in contact with each other.
9 is a rocker arm curved to a predetermined profile;
Reference numeral 20 denotes a rocker arm support surface 2 that is disposed approximately along the back surface 19 of the rocker arm 17 and that the back surface 19 contacts as a fulcrum.
1, this lever 20 has a bifurcated rocker guide portion 22 on both sides of its substantially central portion, and the support shaft 18 of the rocker arm 17 is attached to the rocker guide portion 22.
are slidably fitted together, and the lever 20 is bracketed between the support shaft 8 and the lever 20.
A coil spring n for biasing the fourth side is compressed. In addition, one end 20a of the upper bar 20 on the pulp side is supported in contact with an adjusting screw or screw 24 at the tip edge of the bracket 14, and one end 20b on the cam side is embedded in the bracket 14. It is supported by a hydraulic actuator 25, and the inclination of the lever 20 is controlled by the expansion and contraction of this hydraulic actuator 25.

The hydraulic actuator 25 expands and contracts in its entire length by being moved by a control rack 26 that operates according to engine operating conditions, and is rotatably fitted into a cylinder barrel 27 recessed in the bracket 14. After the control sleeve with which the pinion part 28a meshes with the control rack 26, there is a bottomed cylindrical outer cylinder part 29 which is slidably disposed in the control sleeve 28 along the axial direction, and this outer cylinder. An inner cylinder part 31 is slidably disposed within the section 29 and has an oil reservoir chamber 30 therein; A hydraulic chamber 33 is defined within the outer cylinder section 29 by the inner cylinder section 31, and this hydraulic chamber 33 serves as a check valve. It communicates with the oil reservoir chamber 30 via 34. A semicircular pivot portion 29 is attached to the top of the outer cylinder portion 29.
& is formed, and the pivot portion 29a is pivotally fitted to one end 20b of the lever 20. on the other hand,
The above oil? The IM chamber 30 is provided through oil holes 35 and 36 opened in the side walls of the inner cylinder part 31 and the outer cylinder part 29, respectively, and a hydraulic pressure supply passage 37 opened along the circumferential direction in the control sleeve path. , oil gear lary 38 of bracket 14
The oil holes 5 and 36 are in constant communication with each other, and the communication state between the oil hole 36 of the outer cylinder portion 29 and the oil gear rally 38 is regulated by the oil pressure supply passage 37. That is, as shown in FIG. 3, the hydraulic pressure supply passage 37 is formed such that the passage end m37a on the proximal end side of the control sleeve 28 is formed at one short position along the circumferential direction. The axial position of the passage edge 37b on the tip side of the sleeve gradually changes along the circumferential direction, and the opening is generally triangular as a whole. Tip side>m M end a
37b is the limit for communication with the oil hole 36, and therefore 'I!' is regulated by the control rank 26. !
lJ @U outer cylinder ++l depending on the rotational position of sleeve Z8
The protruding oJ function stroke l of S29 changes. Note that the passage edge 37a on the proximal end side can be formed into any arbitrary shape when the passage 37 is in communication with the oil gear rally 38; It may be something.

Further, the outer cylindrical portion z9 has a pivot portion 29 as shown in FIG.
The fitting part 2 (IC) between the lever 20 and the lever 20 prevents rotation.

As shown in FIG. 5, the control rack 26 is configured to operate the sleeves 28 of the cylinders in sequence, and may be provided with an appropriate actuator 41 such as a near motor or hydraulic cylinder at one end. The amount of movement is determined by the displacement of a potentiometer, etc., and the direction device 42, and the amount of movement is 4! A is issued and feedback control is performed directly on target 1. That is, various data 43 such as suction negative pressure, engine speed, cooling water temperature, etc.
Based on this, the arithmetic circuit 44 and the control 1st shift determination output conversion circuit 45 output a control target signal according to the engine operating conditions, and the comparison circuit 46 outputs a control target signal and the control target signal.
The output a from the 1-displacement 1 extractor 42 via the converter 47
The difference detection circuit 48 outputs the same number corresponding to the II'Iii run of the 1IIIth person. Then, the output circuit 49 is valved by this ・aIIi difference signal to drive the actuator 41, and the control rack 26
The forward and backward positions of the engine are controlled directly according to engine operating conditions.

Next, the operation of the above configuration will be explained.

First, in FIG. 3, when the control rack 2b is controlled to move to the left in the figure, the relative rotation of the control sleeve 28 and the outer part 29 causes the oil hole 36 to reach the limit that can be traced, that is, the passage end. The axial position of the edge 37b moves upward in the figure, and the protrusive stroke l of the outer cylinder part 29 decreases as indicated by 11 in FIG. 3. In other words, the outer surface 2
9 projects the biasing force of the coil spring 32,
Along with this, lubricating oil is supplied into the hydraulic chamber 33 from the oil gear gallery 38, but this oil is no longer supplied when the oil hole 36 is closed at the passage edge 37t) of the hydraulic pressure supply passage; , the outer cylinder part 29 does not protrude any further,
As a result, the total length of the hydraulic actuator 25 becomes shorter as the stroke moves to the right as oil in the hydraulic chamber 33 escapes from the gap between the outer cylinder part 29 and the inner cylinder part 31. As a result, the lever 20, whose one end 20a is supported by the adjustment screw 24, swings relatively upward, and when the pulp drive cam 11 is in the base circle, the lever 20, which has one end 20a supported by the adjustment screw 24, swings relatively upward, and when the pulp drive cam 11 is in the base circle,
It becomes a state separated from. Therefore, when the lift of the curl drive cam 11 starts (from this state), as shown in FIG.
As shown in the figure, the valve opening timing is delayed by a certain period of time from the rise of the pulp drive cam 11, and similarly, the closing P timing is a certain period of time earlier than the fall of the valve m+lJ cam 11, and when the pulp drive cam 11 is at its peak lift. The result is a large lift and a small amount.

Here, a rotational force acts on the lever 20 in the clockwise direction in the figure as the rocker arm 17 is pushed up, but the hydraulic pressure of the hydraulic pressure amount 33 is maintained in the hydraulic actuator 25 by the action of the check valve 34. Therefore, the overall view of the hydraulic actuator 25 hardly changes, and the inclination of the lever 20 remains unchanged. To explain in detail, during Ikaku operation, the hydraulic actuator 25 leaks a little oil in the hydraulic chamber 33 from the N gap with the control sleeve path every time the pulp drive cam 11 is lifted. , and at the end of the lift, the oil gear valve opens the oil reservoir chamber (support) to replenish the required amount of oil into the hydraulic chamber 33.As a result, macroscopically, the oil hole is always closed. The amount of protrusion of the outer cylindrical portion 29 is insufficient to reach a state in which the upper part of the outer cylinder 36 is just visible inside the hydraulic pressure supply passage 37, that is, a state in which the amount of oil leakage and the supplementary charge are balanced. Passage y1 prayer acupuncture 37
According to the shape b, the total length of the rotational position of the control sleeve 28 can always be accurately obtained.

Next, when the control rack 26 moves to the right in FIG. 3 according to the transmission operating conditions, the outer cylinder part 29 of the hydraulic actuator 25 is determined from the position and thread between the hydraulic supply passage 37 and the oil hole 36. Since the ejectable strokes of the pulp drive cam 110 extend as shown in 6, there is a period when the reaction force of the pulp spring 13 does not act on the lever 20.
Period I when the rocker arm 17 is in contact with the base circle
At Mj, its total length increases in accordance with the stroke J. Therefore, the lever 20 swings counterclockwise,
The back surface 19 of the rocker arm 17 and the rocker arm support portion 21 of the lever 20 are in close proximity. Therefore, from this state, when the lift of the pulp drive cam 11 starts, the intake and exhaust valves 12 move at a rate approximately the same as that of the rise and fall of the pulp drive cam 11, as shown in FIG. 6(b). It opens and closes at the right timing, and the foot of the maximum lift becomes a person. Also, during this lift, due to the action of the check valve 34, the reno < -20
As mentioned above, the slope of is maintained.

Note that when the control rack 26 is moved to the left in the figure again from the state in which the hydraulic actuator 25 is extended as shown above, the oil leakage at each cam lift will change as described above.
c, the width gradually becomes shorter, but the leakage amount is: I
By installing it in a straight line, even if the water changes suddenly, it will actually be able to be followed up with just a few cam lifts.

According to the configuration in which the hydraulic actuator 25 is used for each reno (-20) in this way, the inclination of the reno (-20) can be quickly controlled during the period when the reaction force of the nokulp spring 13 does not act. Actuator 25
The driving force required for the control system actuator 41 is extremely small, there is no need to worry about installing a large and powerful hydraulic system as in the past, and power loss can be significantly reduced, and the lever 20 responds to changes in operating conditions. The properties are also good. Furthermore, there is a 4% risk of premature wear on the lever 20 as in the conventional case. Moreover, control rack 26
The amount of protrusion of the hydraulic actuator 25 can be controlled with crystal precision depending on the rotational position of the control sleeve 4, which is not affected by changes in oil viscosity, etc., and variations in each hydraulic actuator 25 can be prevented even in a multi-cylinder engine. It never occurs.

The valve clearance required to cope with thermal expansion of the valve stem 12a can be adjusted very easily by moving the adjustment screw 24, which supports one end of the lever 2o, back and forth.

Next, FIG. 7 shows a different embodiment of the hydraulic actuator 25 that moves on the control rack 26. In this embodiment, the control sleeve 281 body is in the protruding section Vj.
The control sleeve 28' has a hemispherical pivot portion side 'b, which is fitted into one end 20b of the lever 20, and an inner cylindrical portion 31 is disposed within the control sleeve 28'.

The hydraulic pressure supply f provided to this control sleeve A' is
ii% 37' is always in communication with the oil hole 35 of the inner cylinder part 31, while the limit of communication with the oil gear rally 38 changes depending on the rotation axis of the control sleeve 28', and is different from the above embodiment. On the other hand, as shown in FIG. 8, the passage edge 37'a on the proximal end side, which is the limit for communication, has an inclined, substantially triangular shape. Therefore, in this embodiment as well, as in the previous embodiment, it is possible to maintain the tilted position 1t of the lever 20 according to the position of the control rack 26 with good angle <1l (Ii).
In the illustrated example, a separate sleeve 51 is fixed to the bracket 14, but it is also possible to omit this.

An embodiment of the present invention has been described above, but the present invention is/
/J Theory The present invention is not limited to these examples. For example, as a means for driving the control sleeve of the hydraulic actuator, in addition to the above-mentioned engagement mechanism between the binion portion and the control rack, a link mechanism or a winding mechanism of a rope or belt may be used. Furthermore, instead of simply increasing or decreasing the total length of the hydraulic actuator in response to rotation of the control sleeve in one direction, it is also possible to configure the hydraulic actuator to increase or decrease in accordance with a predetermined characteristic.

As is clear from the above explanation, according to this proposal, the inclination position of the lever can be changed to i[lJ 11!41 for each valve by using the rest period when the intake and exhaust valves are not lifted. Therefore, the driving force is small, and the large 7
It eliminates the need to use a cutter, solves the problems of power loss and early pillars of the lever temple, and
The overwave response of tl # is the same as above. In addition, since the extension/retraction position of the hydraulic actuator is forcibly regulated by oil supply regulation according to the 1" transmission position of the control sleeve, there is no possibility that the 1111m run will be restricted due to changes in the viscosity of the oil.
Even in the case of high speed control, it is possible to prevent variations among cylinders and to achieve highly accurate control.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional intake/exhaust valve drive device, Fig. 2 is a sectional view of the intake/exhaust valve drive device +Pt according to the present invention, Fig. 3 is a side view of the main parts of the hydraulic actuator, and Fig. 4 The figure is a perspective view of the main parts, FIG. 5 is a block diagram showing the control circuit of the control rack, FIG. 6 is a lift characteristic diagram showing an example of the valve lift characteristic of the present invention, and FIG. 7 is a diagram showing the lift characteristic according to the present invention. Intake/exhaust valve part @I side view of the main part showing different embodiments of the device, Figure 8 is the jiA of the hydraulic actuator.
FIG. 11... Valve drive cam, 12... Intake and exhaust valve, 14
...Bracket, 17...Rocker arm, 20.l
・Lever, 21... Mouth lock arm support surface, 7.5...
・Hydraulic actuator, 2G...Control rack, 28.26'...Control unit IJ-7', 37.37
'... Hydraulic supply passage; 58... Oil gear rally.

Claims (2)

[Claims] (1) A valve drive system that rotates in synchronization with engine rotation,
- a rocker arm whose abutment contacts the pulp drive cam and whose other end is linked to the pulp stem; and a lever provided with a rocker arm support surface that is disposed approximately along the back of the rocker arm and whose front surface comes into contact with the fulcrum; , a bracket that supports 5t% of the pulp side of this lever, and the lever of the above lever.
An intake/exhaust valve for an internal combustion engine, comprising a hydraulic actuator that supports one end of the lever on the cam side to control tH, and whose expansion and contraction are regulated by regulating oil supply to a hydraulic chamber according to the rotational position of a control sleeve. Drive device. (2) The hydraulic actuator includes a control sleeve that is mounted low on the bracket and rotates in conjunction with the control rack, and a control sleeve that is slidably disposed within the control sleeve and has an external part that is connected to the lever. a cylindrical portion, an inner cylindrical portion that is slidably disposed within the outer surface portion and has an oil reservoir chamber therein, a hydraulic chamber defined between the inner rtIi portion and the outer cylindrical portion, and the hydraulic chamber. a coil spring compressed and disposed in the oil reservoir chamber; a check valve interposed between the hydraulic pressure chamber and the oil reservoir chamber; and an oil hole opening in the side wall of the outer cylinder part and constantly communicating with the oil reservoir chamber. , which is formed along the circumferential direction of the control sleeve to communicate the oil gear lary of the bracket with the oil hole, and has a passage end edge that is the limit of communication with the oil hole with respect to the protrusion of the outer cylindrical portion. 1. An intake/exhaust valve driving device according to claim 1, which comprises a hydraulic pressure supply passage whose position changes along the circumferential direction of the control sleeve.