JP2010174763A - Double link type variable compression ratio device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively attenuate vibration of a variable compression ratio device under a heavy load caused by a combustion load by using a hydraulic piston mechanism 50 for changing a compression ratio. <P>SOLUTION: In a device including a double link type variable compression ratio mechanism and determining compression ratio by rotation position of a control shaft 18, a main actuator 30 using an electric motor 31 is connected via a first and a second links 42, 43, and a piston rod 55 of the hydraulic piston mechanism 50 is connected to the second link 43. In acceleration, compression ratio is quickly reduced according to combustion load by opening an oil chamber 53. At the minimum compression ratio position of the control shaft 18, three of the first link 42, the second link 43 (between connection points 44 and 46), and the piston rod 55 are arranged in one straight line. Consequently, force by alternating torque acting on the control shaft 18 is efficiently transferred to the hydraulic piston mechanism 50, and the hydraulic piston mechanism 50 functions as a kind of a hydraulic damper. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multi-link variable compression ratio device for an internal combustion engine using a multi-link piston-crank mechanism, and more particularly to an improvement of an actuator mechanism for changing the compression ratio.

  In order to variably control the compression ratio of an internal combustion engine, as exemplified in Patent Documents 1 and 2, a multi-link variable compression ratio device using a multi-link piston-crank mechanism is known. The piston and crankshaft of the internal combustion engine are connected via a plurality of link members, and are provided with a control link that restricts the degree of freedom of these link members. By changing the dynamic fulcrum position), the piston position is relatively displaced up and down to change the compression ratio. For example, a control shaft having an eccentric shaft to which the control link base end is connected is used to change the swing fulcrum position of the control link, and the rotational position of the control shaft is changed by an actuator such as an electric motor. It has a configuration.

  Further, in Patent Document 3, an electromagnetic clutch is interposed between a servo motor serving as an actuator and a control shaft, and the variable compression ratio mechanism becomes uncontrollable with a high compression ratio due to, for example, seizure of the servo motor. In this case, it is disclosed that the compression ratio variable mechanism is brought into a free state by shutting off the electromagnetic clutch, and is naturally returned to the low compression ratio state by the combustion pressure.

JP 2000-73804 A JP 2002-215902 A JP 2004-169660 A

  In the multi-link type piston-crank mechanism, a large vibration is generated by a combustion load, an inertial load of each component that reciprocates, and the like. In particular, the vibration increases in a high load region where the combustion load is large.

  In general, a variable compression ratio device for an internal combustion engine is controlled to a low compression ratio in order to avoid knocking in a high load range while a high compression ratio is set in a low and medium load range to improve thermal efficiency. Thus, in order to increase the responsiveness of changes in the compression ratio, such as when the load suddenly increases in a low-medium load region where the compression ratio is high, the actuator tends to increase in size.

  Therefore, the present invention is provided with a hydraulic piston mechanism that is a kind of actuator capable of changing the compression ratio in addition to the main actuator, and at the same time, the damping of vibration is achieved by this hydraulic piston mechanism. That is, the present invention has a control link in which a piston and a crankshaft of an internal combustion engine are connected via a plurality of link members, and restricts the degree of freedom of these link members. Is connected to the eccentric shaft of the control shaft in a swingable manner, and in a multi-link variable compression ratio device in which the compression ratio changes depending on the position of the eccentric shaft according to the rotational position of the control shaft, an arm fixed to the control shaft And a hydraulic actuator that is linked to the link mechanism and can change the compression ratio by moving the link mechanism. The first link that is swingably connected to the arm and the piston rod of the hydraulic piston mechanism are in direct contact with each other in a predetermined low compression ratio state. It is characterized in that aligned above.

  Alternatively, the angle formed by the first link pivotably connected to the arm and the piston rod of the hydraulic piston mechanism is configured to be an angle closest to 180 ° in the lowest compression ratio state.

  The variable compression ratio device is controlled to a low compression ratio in the engine high load range. At this time, since the first link and the piston rod of the hydraulic piston mechanism are in a straight line shape or a posture close to this, the alternating torque that acts on the control shaft via the control link due to combustion load or inertia load is effectively hydraulic. Input to the piston mechanism. Therefore, the hydraulic piston mechanism for changing the compression ratio in addition to the main actuator functions as a kind of hydraulic damper, and effectively attenuates the vibration of the variable compression ratio device in the high load range.

  According to the present invention, the hydraulic piston mechanism for changing the compression ratio is also used as a kind of hydraulic damper, and the vibration of the multi-link piston-crank mechanism in the engine high load region is effectively suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows one Example of this invention. Explanatory drawing which shows the link attitude | position in a high compression ratio state. Structure explanatory drawing which shows the different Example of this invention. Structure explanatory drawing which shows an example of the whole structure of a multilink type variable compression ratio apparatus.

  FIG. 4 shows an example of the basic configuration of a multi-link variable compression ratio device to which the actuator mechanism of the present invention is applied. As shown in the drawing, a piston is placed in a cylinder 6 formed in a cylinder block 5. 1 is slidably disposed, and one end of an upper link 11 is connected to the piston 1 via a piston pin 2 so as to be swingable. The other end of the upper link 11 is rotatably connected to one end portion of the lower link 13 via a first connecting pin 12. The lower link 13 is swingably attached to the crankpin 4 of the crankshaft 3 at the center thereof. The piston 1 receives combustion pressure from a combustion chamber defined above. The crankshaft 3 is rotatably supported on the cylinder block 5 by a crank bearing bracket 7.

  One end of a control link 15 is rotatably connected to the other end of the lower link 13 via a second connecting pin 14. The other end of the control link 15 is swingably supported by a part of the internal combustion engine body, and the position of the swing fulcrum 16 is displaced with respect to the internal combustion engine body in order to change the compression ratio. It is possible. Specifically, a control shaft 18 extending in parallel with the crankshaft 3 is provided, and the other end of the control link 15 is rotatably fitted to an eccentric shaft 19 provided eccentric to the control shaft 18. The control shaft 18 is rotatably supported between the crank bearing bracket 7 and the control bearing bracket 8.

  Therefore, when the control shaft 18 is rotationally driven by an actuator mechanism to be described later for changing the compression ratio, the center position of the eccentric shaft 19 serving as the swing fulcrum 16 of the control link 15 moves relative to the engine body. As a result, the motion restraint condition of the lower link 13 by the control link 15 changes, the stroke position of the piston 1 with respect to the crank angle changes, and consequently the engine compression ratio changes.

  The present invention is not limited to the specific type of multi-link variable compression ratio device as shown in the figure, but can be applied to various types of variable compression ratio devices using a multi-link type piston-crank mechanism. It is possible.

  FIG. 1 shows a configuration of an actuator mechanism that is a main part of the present invention. This actuator mechanism includes a main actuator 30 using an electric motor 31 and a hydraulic piston mechanism 50 including a cylinder 51 and a piston 52. I have. In this embodiment, the main actuator 30 outputs the rotation of the electric motor 31 to a coaxial output shaft 32 via a speed reduction mechanism (not shown), and a connecting rod by swinging of an arm 33 fixed to the output shaft 32. 34 is configured to perform a motion approximating a linear motion. The connecting rod 34 is swingably connected to the tip of the arm 33 at a connection point 47. The main actuator 30 may be configured to linearly move using a known ball screw mechanism.

  The hydraulic piston mechanism 50 has a configuration in which an oil chamber 53 is defined by a piston 52 and a return spring 54 is provided in a direction in which the oil chamber 53 expands, and a piston rod 55 connected to the piston 52 includes a piston rod 55. When urged in the backward direction, the oil in the oil chamber 53 is compressed to generate hydraulic pressure, and the load in the compression direction is supported. An open / close valve (not shown) is interposed in the oil passage leading to the oil chamber 53, and the tip of the oil passage is connected to a reservoir tank that is under atmospheric pressure or relatively low pressure.

  An arm 41 extending in the radial direction is fixed to the control shaft 18, and one end of the first link 42 is swingably connected to the tip thereof via a connection point 48. A second link 43 is swingably connected to the other end of the first link 42. In this embodiment, the second link 43 is a triangular link having connection points 44, 45, 46 at three locations, and the other end of the first link 42 is swingably connected to the connection point 44. The tip of the connecting rod 34 is swingably connected to the connecting point 45, and the tip of the piston rod 55 is swingably connected to the connecting point 46.

  As can be understood by those skilled in the art, the arms 33 and 41 do not necessarily have a physical arm member. For example, a pin provided eccentrically on the end surface of the control shaft 18 is regarded as the arm 41. be able to.

  The main actuator 30 and the hydraulic piston mechanism 50 that are connected to each other via the link mechanism as described above are related to each other, and if the piston 52 of the hydraulic piston mechanism 50 is moved while the main actuator 30 is fixed, the control shaft 18 rotates. On the contrary, if the main actuator 30 is moved with the hydraulic piston mechanism 50 fixed, the control shaft 18 is also rotated.

  Although the control link 15 described above is schematically shown in the figure, the combustion load acting on the piston 1 of the engine acts in the direction of pulling up the eccentric shaft 19 as indicated by the arrow F on the control link 15. To do. Therefore, in the configuration of this embodiment, the control shaft 18 receives a combustion load in the counterclockwise direction, and the combustion load is applied as a compression load to the oil chamber of the hydraulic piston mechanism 50 via the first and second links 42 and 43. Works. When the control shaft 18 is displaced in the clockwise direction, the compression ratio increases, and when the control shaft 18 is displaced in the counterclockwise direction, the compression ratio decreases. Therefore, as the hydraulic piston mechanism 50, the piston rod 55 protrudes. The displacement in the direction (left side in the figure) is on the high compression ratio side, the displacement in the backward direction of the piston rod 55 (right side in the figure) is on the low compression ratio side, and the main actuator 30 is the left side in the figure of the connecting rod 34. The displacement toward is the high compression ratio side, and the displacement to the right in the figure is the low compression ratio side.

  In this embodiment, the hydraulic piston mechanism 50 is basically controlled in a binary manner, and if the target compression ratio is on the high compression ratio side as in the low-medium load region, the piston rod 55 is in a protruding position, The oil chamber 53 is expanded. This state is restored using the urging force of the return spring 54, but the oil chamber 53 is sealed by the above-described on-off valve at the position where the piston rod 55 protrudes, and the force acting on the piston rod 55 can be resisted. it can. In this state, the main actuator 30 is feedback-controlled so that the position of the control shaft 18 corresponds to the target compression ratio.

  If the target compression ratio is on the low compression ratio side as in the high load region, the oil chamber 53 is opened by the on-off valve, and the piston 52 is displaced by the combustion load input through the piston rod 55, so that the piston rod 55 is the retracted position. In this state, the main actuator 30 is feedback controlled so that the position of the control shaft 18 corresponds to the target compression ratio.

  On the other hand, when the engine load suddenly increases in a state where the engine is operating at a high compression ratio (that is, in a low / medium load region), that is, when the accelerator opening operated by the driver increases rapidly, The on-off valve is opened and the oil chamber 53 is opened. As a result, the hydraulic piston mechanism 50 is instantaneously displaced under the force of the combustion load F, the piston rod 55 is retracted, and the compression ratio of the engine immediately decreases. In parallel with this, the main actuator 30 is also displaced to the low compression ratio side, but the compression ratio is lowered without waiting for the displacement of the main actuator 30, and therefore knocking can be avoided reliably.

  It should be noted that the position of the piston rod 55 can be determined by the balance between the urging force of the return spring 54 and the combustion load that changes depending on the level of the engine load, without having an on-off valve controlled from the outside. .

  The variable range of the compression ratio by the main actuator 30 and the hydraulic piston mechanism 50 (in other words, the amount of change in the angle of the control shaft 18) is the lowest compression in the main actuator 30 or the hydraulic piston mechanism 50 in the above embodiment. The entire range from the compression ratio to the maximum compression ratio cannot be covered, and the compression ratio of the entire range can be realized by controlling both. That is, when the main actuator 30 is moved in a state where the hydraulic piston mechanism 50 is fixed to the low compression ratio side, the control shaft 18 is displaced from the lowest compression ratio as the compression ratio within an angle range corresponding to the predetermined intermediate compression ratio. On the other hand, if the hydraulic piston mechanism 50 is moved in a state where the main actuator 30 is fixed to the high compression ratio side, the control shaft 18 is displaced as a compression ratio within a range of angles corresponding to the maximum compression ratio from a predetermined intermediate compression ratio. The amount of change in compression ratio that can be realized by the hydraulic piston mechanism 50 is relatively small with respect to the amount of change in compression ratio by the main actuator 30. In this way, by configuring both the main actuator 30 and the hydraulic piston mechanism 50 so as to realize the entire compression ratio range, the main actuator 30 and the hydraulic piston mechanism 50 have relatively small configurations, respectively. Since the hydraulic piston mechanism 50 does not require a large stroke, a small and small capacity is sufficient, and a small amount of oil is required. Moreover, even if one or both of the main actuator 30 and the hydraulic piston mechanism 50 cannot be controlled, the control shaft 18 does not rotate beyond a position corresponding to a predetermined maximum compression ratio. The situation where the position of 1 rises excessively and interferes with the valve can be reliably avoided.

  FIG. 1 shows the attitude of the link mechanism when the control shaft 18 is at the lowest compression ratio position. At this time, both the main actuator 30 and the hydraulic piston mechanism 50 are on the low compression ratio side. In this embodiment, as shown in the figure, at this lowest compression ratio position, the first link 42, the second link 43 (specifically, between the connecting points 44 and 46) and the piston rod 55 are in a straight line. Align. Therefore, the force generated in the tangential direction of the connection point 48 by the alternating torque acting on the control shaft 18 is efficiently transmitted to the hydraulic piston mechanism 50, and the hydraulic piston mechanism 50 functions as a kind of hydraulic damper, so that the control shaft 18 Thus, the vibration of the entire variable compression ratio device can be effectively suppressed. In addition, you may comprise so that it may restrict | limit to the state slightly bent near 180 degrees instead of becoming a perfect straight line shape.

  In addition, at the lowest compression ratio position shown in FIG. 1, at the same time, the angle θ1 formed by the arm 41 and the first link 42 is near 90 °, preferably 90 °. Thereby, the rotational torque of the control shaft 18 is efficiently converted as a force along the longitudinal direction of the first link 42. Further, at the same time, the attitude of the control link 15 on the control shaft 18 is such that the angle θ2 formed by the radial line of the control shaft 18 passing through the center of the eccentric shaft 19 and the control link 15 is near 90 °, preferably 90 °. Thereby, the force along the longitudinal direction of the control link 15 is efficiently converted as the rotational torque of the control shaft 18.

  Therefore, as a whole, the hydraulic piston mechanism 50 can most effectively give a vibration damping action to vibration input caused by a large combustion load in a high load region (low compression ratio state). Therefore, the necessity of measures for strength and vibration and noise is reduced, and the control shaft 18 and the control link 15, and consequently the increase in the size and weight of the engine body structure such as the cylinder block and the ladder frame that support them are suppressed. be able to.

  FIG. 2 shows the attitude of the link mechanism when the control shaft 18 is at the highest compression ratio position. At this time, both the main actuator 30 and the hydraulic piston mechanism 50 are on the high compression ratio side. In this state, the first link 42, the second link 43 (specifically, between the connection points 44 and 46) and the piston rod 55 are not necessarily arranged in a straight line, but even in this case, the hydraulic piston mechanism 50 is It will exhibit a certain amount of vibration damping action.

  Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the second link 43 is not provided, and the tip of the first link 42, the tip of the connecting rod 34, and the tip of the piston rod 55 are arranged. They are connected to each other at a connecting point 49 common to the three members so as to be swingable. In addition, you may comprise so that the hydraulic piston mechanism 50 can rock | fluctuate as needed.

  FIG. 3 shows the posture of the link mechanism when the control shaft 18 is at the lowest compression ratio position, as in FIG. 1, and both the main actuator 30 and the hydraulic piston mechanism 50 are on the low compression ratio side. Similar to the embodiment, at the lowest compression ratio position, the first link 42 and the piston rod 55 are in a straight line, and the angles θ1 and θ2 are both 90 °.

  As mentioned above, although one Example of this invention was described, this invention is not limited to these Examples, A various change is possible. For example, the hydraulic piston mechanism 50 is not limited to one of the above-described types of oil chambers or merely a binary moving type, and can be actively controlled to a type having two oil chambers or an intermediate position. Various types can be used.

  Further, in the above-described embodiment, it has been described that the desired link posture is obtained when the combustion compression load is at the lowest compression ratio position. However, even if the position is not necessarily the lowest compression ratio position, a predetermined value close to the lowest compression ratio is obtained. If the link posture relationship described above is established at the compression ratio position, the most effective vibration damping action can be obtained under a predetermined high load condition corresponding to the compression ratio.

  Each of the attached drawings is an explanatory diagram for explaining the configuration and principle of the present invention, and needless to say, the dimensional relationship of each part is not strict.

DESCRIPTION OF SYMBOLS 1 ... Piston 3 ... Crankshaft 11 ... Upper link 13 ... Lower link 15 ... Control link 18 ... Control shaft 19 ... Eccentric shaft 30 ... Main actuator 31 ... Electric motor 50 ... Hydraulic piston mechanism 51 ... Cylinder 52 ... Piston 42 ... 1st Link 43 ... Second link 55 ... Piston rod

Claims (8)

A piston and a crankshaft of an internal combustion engine are connected via a plurality of link members, and have a control link that limits the degree of freedom of these link members, and the base end of the control link is an eccentric shaft of the control shaft In a multi-link variable compression ratio device, wherein the compression ratio changes depending on the position of the eccentric shaft according to the rotational position of the control shaft.
A main actuator that is linked to the arm fixed to the control shaft via a link mechanism and moves the control shaft in the rotation direction, and a hydraulic piston that is linked to the link mechanism and can change the compression ratio by moving the link mechanism An internal combustion engine characterized in that a first link pivotably connected to the arm and a piston rod of the hydraulic piston mechanism are aligned with each other in a predetermined low compression ratio state Multi-link variable compression ratio device.   The multi-link variable compression ratio device for an internal combustion engine according to claim 1, wherein the arm and the first link are orthogonal to each other in the predetermined low compression ratio state.   3. The internal combustion engine according to claim 1, wherein the control link has a posture orthogonal to a radial line of the control shaft passing through the eccentric shaft in the predetermined low compression ratio state. Link type variable compression ratio device. A piston and a crankshaft of an internal combustion engine are connected via a plurality of link members, and have a control link that limits the degree of freedom of these link members, and the base end of the control link is an eccentric shaft of the control shaft In a multi-link variable compression ratio device, wherein the compression ratio changes depending on the position of the eccentric shaft according to the rotational position of the control shaft.
A main actuator that is linked to the arm fixed to the control shaft via a link mechanism and moves the control shaft in the rotation direction, and a hydraulic piston that is linked to the link mechanism and can change the compression ratio by moving the link mechanism And an angle formed between a first link pivotably connected to the arm and a piston rod of the hydraulic piston mechanism is an angle closest to 180 ° in a minimum compression ratio state. A multi-link variable compression ratio device for an internal combustion engine.   The multi-link variable compression ratio device for an internal combustion engine according to claim 4, wherein the arm and the first link are orthogonal to each other in a minimum compression ratio state.   The multi-link variable compression for an internal combustion engine according to claim 4 or 5, wherein the control link has a posture orthogonal to a radial line of the control shaft passing through the eccentric shaft in a minimum compression ratio state. Ratio device.   The multi-link variable compression ratio device for an internal combustion engine according to any one of claims 1 to 6, wherein the first link and the tip of the piston rod are directly linked to each other.   The internal combustion engine according to any one of claims 1 to 6, wherein a second link that is swingably connected to each other is interposed between the first link and the tip of the piston rod. Multi-link variable compression ratio device.

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