JP2006336659A - Variable valve operating device for internal combustion engine - Google Patents

Abstract

A valve lift characteristic that is variably controlled is detected indirectly and reliably at a place where it does not move at high speed.
An annular disk 29 is interposed between a flange portion of a sleeve connected to a drive shaft 21 and a flange portion of a camshaft 22. If the center of the annular disc is decentered, rotation becomes inconstant speed and valve lift characteristics are obtained. Changes. A disk housing 34 that holds the annular disk 29 is supported by a first eccentric cam 41 and a second eccentric cam 43. When the first eccentric cam 41 is rotationally displaced by the hydraulic actuator 46, the disk housing 34 moves, and the amount of eccentricity of the annular disk 29 changes. A potentiometer 5 is attached to one end of the control cam shaft 42 of the first eccentric cam 41, and an actual valve lift characteristic is detected based on its rotational position.
[Selection] Figure 1

Description

  The present invention relates to a variable valve device that variably controls the opening / closing timing and operating angle of an intake valve and an exhaust valve according to the operating state of an internal combustion engine, and more particularly to a device that detects the valve lift characteristics.

  Conventionally, as shown in, for example, Patent Document 1 and Patent Document 2, various variable valve devices that variably control the opening and closing timings and operating angles of intake valves and exhaust valves according to the operating state of an internal combustion engine have been proposed. Has been. In addition, a valve lift characteristic detection device that detects how the actual valve lift characteristic is controlled in this type of variable valve apparatus has been conventionally proposed.

  For example, in Patent Document 3, a part of the intake / exhaust valve is made of a magnetic material, or a reflection plate is provided on a part thereof, and the displacement of the intake / exhaust valve is directly measured by a coil or a light receiving element arranged around the valve. Discloses a valve lift characteristic detecting device configured to detect the above.

  Patent Document 4 discloses a configuration for detecting the displacement of a rocker arm or a valve spring retainer that is displaced in relation to an intake / exhaust valve.

Further, Patent Document 5 discloses a valve lift characteristic detection device that indirectly detects a valve lift characteristic by measuring a switching hydraulic pressure for switching and controlling the characteristic of a variable valve operating apparatus.
Japanese Utility Model Publication No.57-198306 JP-A-5-202718 Japanese Utility Model Publication No. 62-21409 JP-A-2-308911 Japanese Examined Patent Publication No. 3-75730

  However, in the apparatus described in Japanese Utility Model Laid-Open No. 62-21409, it is necessary to provide some object to be detected to the valve that moves at high speed, and there is a problem in durability and strength. Although it is necessary to arrange a coil and a light receiving element around the valve, it is very difficult to avoid the interference with the valve spring and it is not practical.

  Also in the apparatus described in Japanese Patent Laid-Open No. 2-308911, since the rocker arm and the valve spring retainer move at high speed, there are still problems in durability and strength.

  In addition, in the method of detecting the valve lift characteristic indirectly from the hydraulic pressure as in the device described in the above Japanese Patent Publication No. 3-75730, the valve lift characteristic is erroneously determined when there is a failure in the hydraulic actuator portion. Resulting in. In other words, the present invention is essentially not applicable to the case where the actual valve lift characteristic is detected to detect a failure of the variable valve gear.

The valve lift characteristic detection device of the present invention has a drive shaft that rotates in synchronization with the rotation of the engine, and a cam that is provided on the same axis of the drive shaft so as to be relatively rotatable and that drives an intake / exhaust valve. A camshaft, a flange portion provided at an end portion of the camshaft and formed with an engagement groove along the radial direction, and provided on the drive shaft side so as to face the flange portion, and in the radial direction And a flange portion formed between the flange portions, and pins that are engaged between the flange portions of the flange portions in opposite directions. Swinging with a first eccentric cam and a second eccentric cam each having an annular disk projecting on the disk and a circular cam portion that rotatably holds the annular disk and is fitted in a pair of cam fitting holes, respectively. Possible supported And a drive mechanism for controlling the rotational position of the first eccentric cam, wherein the valve lift characteristic of the intake and exhaust valves is variably controlled by decentering the center of the annular disk. In
Detection means for detecting the rotational position of the first eccentric cam is provided.

  According to a second aspect of the invention, instead of detecting the rotational position of the first eccentric cam, a detecting means for detecting the rotational position of the second eccentric cam that follows the rotation of the first eccentric cam is provided.

  According to a third aspect of the present invention, the cam shaft of the first eccentric cam is continuous over a plurality of cylinders, and the rotation position thereof is detected by one detection means.

  According to a fourth aspect of the present invention, the drive mechanism is disposed at one end of the cam shaft of the first eccentric cam, and the detection means is disposed at the other end.

  The rotation of the drive shaft is transmitted to the camshaft via a pin that slides in the engaging groove of both flange portions and an annular disk. When the center of the annular disk coincides with the axis of the camshaft, the drive shaft and the camshaft are linked at a constant speed. On the other hand, when the center of the annular disk is decentered from the center of the drive shaft, the drive shaft and the camshaft are interlocked at unequal speed, and the angular velocity of the camshaft changes during rotation. That is, the rotational speed of the camshaft increases or decreases during one rotation, and the actual valve lift characteristic of the intake / exhaust valve driven by the cam changes.

  Here, the amount of eccentricity of the annular disk with respect to the drive shaft is determined by the first and second eccentric cams. That is, when the drive mechanism rotates the first eccentric cam, the disk housing moves along with this, and the amount of eccentricity changes. The second eccentric cam is driven as the disk housing moves.

  According to the first aspect of the present invention, the eccentric amount and thus the valve lift characteristic is detected by detecting the rotational position of the first eccentric cam. Since the valve lift characteristic is mechanically and uniquely determined by the rotational position of the first eccentric cam, there is no room for erroneous detection.

  According to the second aspect of the present invention, instead of the first eccentric cam, the rotational amount of the second eccentric cam and the valve lift characteristic are detected by detecting the rotational position of the second eccentric cam. The second eccentric cam rotates in accordance with the rotation of the first eccentric cam, and the relationship between the rotational positions of both is uniquely determined.

  In the configuration of the third aspect, the valve lift characteristics of the intake and exhaust valves of the plurality of cylinders are simultaneously controlled by a series of eccentric cams. The actual valve lift characteristic is detected based on the rotational position.

  According to the fourth aspect of the present invention, the cam shaft is driven by a drive mechanism disposed at one end of the cam shaft, and the rotational position is detected by the detecting means at the other end.

  According to the valve lift characteristic detecting device for a variable valve operating system for an internal combustion engine according to the present invention, the actual valve lift characteristic is detected from the rotational position of the first eccentric cam that mechanically determines the valve lift characteristic to be variably controlled. Therefore, the valve lift characteristics can be detected regardless of the portion that moves at high speed for each cycle of the engine, and the durability and strength problems can be avoided. Although the valve lift characteristics are indirectly detected, the rotational position of the first eccentric cam is mechanically related to the final valve lift characteristics, and unless the parts are damaged, the actual valve Since it corresponds to the lift characteristic correctly, there is no possibility of causing erroneous detection unlike the conventional one that indirectly detects the valve lift characteristic by detecting the hydraulic pressure.

  According to the second aspect of the present invention, since the rotational position of the second eccentric cam may be detected instead of the first eccentric cam, the degree of freedom in layout increases.

  According to the third aspect of the present invention, the valve lift characteristics of a plurality of cylinders can be controlled at the same time, and this can be detected by one detection means, and there is no need to detect for each cylinder.

  Furthermore, according to the fourth aspect of the present invention, the layout of a relatively large drive mechanism can be facilitated, and when the control cam shaft of the first eccentric cam is damaged in the middle, the abnormality can be reliably detected.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIGS. 1-7 has shown one Example which applied the variable valve apparatus based on this invention to the intake side. In the figure, 21 is a drive shaft to which rotational force is transmitted from an engine crankshaft (not shown) via the timing chain 1 (see FIG. 1), and 22 is arranged on the outer periphery of the drive shaft 21 with a certain clearance and is driven. This is a hollow cylindrical camshaft provided coaxially with the center X of the shaft 21. The drive shaft 21 extends in the longitudinal direction of the engine and is formed in a hollow shape. The camshaft 22 is divided for each cylinder.

  The camshaft 22 is rotatably supported by a cam bearing at the upper end of a cylinder head (not shown) and, as shown in FIG. 1, the intake valve 23 is resisted against the spring force of the valve spring at a predetermined position on the outer periphery. A plurality of cams 26 that are opened through the valve lifter 25 are integrally provided. The camshaft 22 is divided into a plurality of parts as described above, and a flange 27 is provided at one of the divided ends. A sleeve 28 and an annular disk 29 are disposed between the ends of the camshaft 22 divided into a plurality of parts. As shown in FIG. 4, the flange portion 27 is formed with an elongated rectangular engagement groove 30 extending in the radial direction from the hollow portion, and a flange surface 27 a that is in sliding contact with one surface of the annular disk 29. have.

  The sleeve 28 has a small-diameter one end portion rotatably inserted into the other divided end portion of the camshaft 22 and is fitted to the outer periphery of the drive shaft 21 and has a connecting pin 31 penetrating in the diametrical direction. It is connected and fixed to the drive shaft 21 via the via. Further, the flange portion 32 provided on the other end portion of the sleeve 28 is located opposite to the flange portion 27 on the camshaft 22 side, and as shown in FIG. An engaging groove 33 is formed, and a flange surface 28 a that is in sliding contact with the other surface of the annular disk 29 is provided on the outer peripheral surface. The engagement groove 33 is disposed on the opposite side of the engagement groove 30 of the camshaft 22 side flange portion 27 by 180 °.

  The annular disk 29 has a substantially donut plate shape, an inner diameter is formed to be substantially the same as the inner diameter of the camshaft 22, and an annular gap S is formed between the outer peripheral surface of the drive shaft 21. At the same time, the outer peripheral surface 29 a is rotatably held on the inner peripheral surface of the disk housing 34 via an annular bearing metal 35. Also, holding holes 29b and 29c are formed through the respective opposing positions on the diameter lines that are 180 ° different from each other, and the holding holes 29b and 29c have a pair of pins 36 and 36 that engage with the engaging grooves 30 and 33, respectively. 37 is fitted and arranged. The pins 36 and 37 protrude in opposite directions in the camshaft axial direction, and a base portion formed of a cylindrical surface is rotatably fitted and supported in the holding holes 29b and 29c, and from the surface of the annular disk 29. As shown in FIGS. 4 and 5, two-side-width flat portions 36 a, 36 b, 37 a, and 37 b that come into contact with the opposing inner surfaces 30 a, 30 b, 33 a, and 33 b of the engagement grooves 30 and 33 are formed at the protruding tip portions. Is formed. Further, the pins 36 and 37 are positioned in the axial direction. In the protruding direction, the step portions 36c and 37c formed between the cylindrical surface of the pins 36 and 37 and the flat portions 36a, 36b, 37a and 37b and the flanges are provided. The contact with the surfaces 27a and 28a is performed, and the backward direction is performed by contact between the base end surfaces 36d and 37d of the pins 36 and 37 passing through the holding holes 29b and 29c and the flange surfaces 28a and 27a. .

  The disk housing 34 has a substantially triangular shape as shown in FIGS. 1 and 6, and the annular disk 29 is held in the circular opening 34a. And the 1st cam fitting hole 38 and the 2nd cam fitting hole 39 are penetratingly formed in two places used as the top part of a triangle, respectively.

  The circular cam portions 41a and 43a of the first eccentric cam 41 and the second eccentric cam 43 are rotatably fitted in the first cam fitting hole 38 and the second cam fitting hole 39, respectively. Yes.

  As shown in FIG. 1, the second eccentric cam 43 includes a cylindrical shaft portion 43b and a circular cam portion 43a that are eccentric by a predetermined amount, and both are rotatably fitted and integrated. . The circular cam portion 43a is prevented from being detached by the snap ring 3. As shown in FIG. 1, the shaft portion 43 b is press-fitted and fixed to the bracket-like bracket portion 2 of the cylinder head.

  The first eccentric cam 41 includes a control cam shaft 42 that is continuous over a plurality of cylinders along the longitudinal direction of the engine, and a plurality of circular cam portions that are fixed to the cam shaft 42 corresponding to each cylinder. 41a, both of which are eccentric by a predetermined amount. The circular cam portion 41a of each cylinder is eccentric at a predetermined angular position of the cam shaft 42. As shown in FIG. 1, the control cam shaft 42 is rotatably held by the bracket portion 2 via a cam bracket 4. A rotary hydraulic actuator 46 is attached to one end of the control cam shaft 42 located at the rear of the internal combustion engine as a drive mechanism. A rotary potentiometer 5 is attached to the other end of the control cam shaft 42 located at the front of the internal combustion engine as a detecting means for detecting the rotational position of the control cam shaft 42, that is, the phase of the circular cam portion 41a. Yes.

  In this embodiment, the circular cam portion 41a of the first eccentric cam 41 and the circular cam portion 43a of the second eccentric cam 43 have the same diameter, and the eccentric amount thereof is also set equal. However, the present invention is not limited to this.

  FIG. 7 shows a configuration example of a hydraulic circuit for controlling the phase of the hydraulic actuator 46, and a two-blade rotating vane 49 rotatably provided in a cylindrical housing 48 of the hydraulic actuator 46, The rotary vane 49 is provided with first oil chambers 50 and 50 and second oil chambers 51 and 51 which are diagonally located and are connected to the control cam shaft 42. Yes.

  The hydraulic circuit includes first and second oil passages 52a and 52b for supplying and discharging hydraulic pressure to the first and second oil chambers 50 and 51, and a 4-port 2 provided at the ends of both the oil passages 52a and 52b. A position-type electromagnetic switching valve 53, an oil pump 55 provided at the upstream end of the oil main gallery 54, a drain passage 57 that communicates with the oil passages 52a and 52b as needed to return the working oil into the oil pan 56, And a relief valve 58 for controlling the pump discharge pressure to a constant pressure.

  The electromagnetic switching valve 53 is switch-controlled by a controller 59 that detects the engine operating state based on signals such as the engine speed and the intake air amount. As a result, the rotational position of the hydraulic actuator 46 is continuously variably controlled.

  Hereinafter, the operation of the embodiment configured as described above will be described.

  First, in a predetermined operating condition of the engine, for example, in a high speed region, the rotational position of the first eccentric cam 41 is controlled as shown in FIG. At this time, the center Y of the annular disk 29 coincides with the center X of the drive shaft 21. In this case, there is no rotational phase difference between the annular disk 29 and the drive shaft 21, and the center of the camshaft 22 and the center X of the annular disk 29 coincide with each other, so that a rotational phase difference between the two also occurs. Absent. For this reason, the drive shaft 21, the annular disk 29 and the camshaft 22 rotate synchronously at a constant speed via the pins 36 and 37. As a result, a valve lift characteristic as shown by the solid line in FIG.

  On the other hand, for example, in the low speed region of the engine, the rotational position of the first eccentric cam 41 is controlled as shown in FIG. As a result, the center Y of the annular disk 29 and the center X of the drive shaft 21 are decentered from each other so that the amount of eccentricity is indicated by Δ. In this state, similarly to a kind of inconstant speed shaft coupling, an inconstant speed rotation in which the angular velocity of the annular disk 29 changes is obtained. As a result, a phase difference corresponding to the amount of eccentricity Δ is given between the drive shaft 21 and the camshaft 22 as indicated by a one-dot chain line in FIG. Further, the same phase point (P point) exists in the middle of the maximum and minimum points of the rotational phase difference. In the characteristic diagram of FIG. 8B, the phase difference in the direction in which the camshaft 22 is relatively advanced is positive, and the phase difference in the direction in which the camshaft 22 is relatively delayed is negative. The opening timing of the intake valve 23 located in the region where the camshaft 22 is relatively delayed (region before the P1 point and region P2 to P3) is delayed with the phase difference. Conversely, the closing timing of the intake valve 23 located in the region where the camshaft 22 is relatively advanced (region P1 to P2) proceeds with the phase difference. Therefore, a valve lift characteristic as indicated by the alternate long and short dash line in FIG.

  FIG. 6B shows the first eccentric cam 41 rotated by 90 ° in the clockwise direction of the drawing with reference to the concentric control position of FIG. 6A. The rotation of the first eccentric cam 41 is shown in FIG. By changing the position continuously, the amount of eccentricity Δ can be changed continuously, and the valve lift characteristic changes continuously. Further, if the rotation is made counterclockwise in the figure, the phase difference shown in FIG. 8B can be obtained in the reverse direction.

  Note that the second eccentric cam 43 supporting the disk housing 34 together with the first eccentric cam 41 rotates following the rotation of the first eccentric cam 41, as is apparent from FIG. In other words, the disk housing 34 and the first and second eccentric cams 41 and 43 constitute a kind of four-bar linkage mechanism. When the first eccentric cam 41 is rotated as a driving node, the disk housing 34 and the second eccentric cam 41 and 43 are formed. The eccentric cam 43 moves in a limited manner as a driven node.

  Here, the rotational position of the first eccentric cam 41 is detected by the potentiometer 5. The detection signal of the potentiometer 5 is input to the controller 59, and an actual valve lift characteristic is detected based on this signal. That is, the eccentric amount Δ of the disk housing 34 is mechanically and uniquely determined by the eccentric position of the first eccentric cam 41, and the final valve lift characteristic is mechanically and uniquely determined according to the eccentric amount Δ. Is determined. Therefore, if the rotational position of the first eccentric cam 41 is known, the actual valve lift characteristics can be accurately recognized. The controller 59 can detect the abnormality of the drive mechanism, for example, the failure of the hydraulic actuator 46 or the abnormality of the hydraulic system, by comparing the valve lift characteristic detected in this way with the valve lift characteristic that is the control target. .

  According to such detection of the valve lift characteristic, the first eccentric cam 41 itself is not a member that moves at a high speed as the valve is opened and closed, so that it is extremely excellent in terms of durability. Further, since it can be detected at a position away from the intake valve 23 and the cam 26 that move at high speed, there is no restriction on the layout.

  In this embodiment, the valve lift characteristics of each cylinder are variably controlled by the first eccentric cam 41 integrated over a plurality of cylinders, and this can be detected by one potentiometer 5. Is possible. That is, it is not necessary to provide a valve lift characteristic detecting means for each cylinder, and the configuration can be simplified. In particular, in the above embodiment, the hydraulic actuator 46 is disposed at one end of the control cam shaft 42 and the potentiometer 5 is disposed at the other end, so that the layout is easy. Moreover, by providing the hydraulic actuator 46 at the rear end of the engine, layout restrictions with the timing chain 1 and the like can be avoided, and by providing the potentiometer 5 at the front end of the engine on the opposite side of the hydraulic actuator 46, First, there is an advantage that the control cam shaft 42 can be reliably detected when it is broken in the middle.

  In the above embodiment, the rotational position of the first eccentric cam 41 is detected by the potentiometer 5, but instead, the rotational position of the second eccentric cam 43 may be detected by an appropriate sensor. . In this case, since the sensor may be disposed near the second eccentric cam 43 of any cylinder, the degree of freedom in layout increases.

  Moreover, although the example applied to the intake valve side has been described in the above embodiment, it goes without saying that the present invention can be similarly applied to the exhaust valve side. Further, the variable valve mechanism on the intake valve side and the variable valve mechanism on the exhaust valve are arranged in parallel, and each annular disk 29 is eccentric by a disk housing 34 integrated on both the intake valve side and the exhaust valve side. It is also possible to configure it. In this case, the valve lift characteristics on both the intake valve side and the exhaust valve side can be variably controlled by the single first eccentric cam 41, and the valve lift characteristics can be detected by one detection means. it can.

1 is an exploded perspective view showing an embodiment of the present invention. The top view which shows the principal part of a present Example. The side sectional view of the notch of the principal part similarly. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. BB sectional drawing of FIG. It is explanatory drawing which shows the structure of a disk housing and a 1st, 2nd eccentric cam, Comprising: (A) is a concentric state, (B) is explanatory drawing which shows the mode of an eccentric state. The circuit diagram of the hydraulic circuit which drives a hydraulic actuator. The characteristic view which shows the rotational phase difference and valve lift characteristic of a drive shaft and a camshaft by contrast.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Potentiometer 21 ... Drive shaft 22 ... Cam shaft 23 ... Intake valve 29 ... Annular disk 34 ... Disk housing 41 ... 1st eccentric cam 43 ... 2nd eccentric cam 46 ... Hydraulic actuator

Claims (4)

A drive shaft that rotates in synchronization with the rotation of the engine;
A camshaft provided on the outer peripheral surface of the drive shaft so as to be relatively rotatable on the same axis and driving an intake / exhaust valve;
A flange portion provided at an end portion of the camshaft and formed with an engagement groove along a radial direction;
A flange portion provided on the drive shaft side so as to face the flange portion, and having an engagement groove formed along a radial direction;
An annular disc that is disposed between the flange portions, and on both sides thereof, pins that engage in the respective engagement grooves of the flange portions project in opposite directions; and
A disk housing rotatably supported by the first eccentric cam and the second eccentric cam, each having a circular cam portion that is rotatably held by the pair of cam fitting holes;
A drive mechanism for controlling the rotational position of the first eccentric cam;
A variable valve operating apparatus for an internal combustion engine that variably controls the valve lift characteristics of the intake and exhaust valves by decentering the center of the annular disk,
2. A valve lift characteristic detecting device for a variable valve operating system for an internal combustion engine, comprising detecting means for detecting the rotational position of the first eccentric cam.   2. The detecting device according to claim 1, further comprising a detecting means for detecting a rotational position of the second eccentric cam driven by the rotation of the first eccentric cam instead of detecting the rotational position of the first eccentric cam. A valve lift characteristic detecting device for a variable valve operating device of an internal combustion engine.   2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the cam shaft of the first eccentric cam is continuous over a plurality of cylinders, and the detection position is detected by one detection means. Valve lift characteristic detection device.   4. The valve lift characteristic detection of a variable valve gear for an internal combustion engine according to claim 3, wherein the drive mechanism is arranged at one end of the cam shaft of the first eccentric cam and the detection means is arranged at the other end. apparatus.

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