JP6509666B2 - Variable compression ratio device for internal combustion engine - Google Patents

Description

  The present invention relates to, for example, a variable compression ratio device that makes an actual compression ratio of an internal combustion engine variable.

  As a conventional variable compression ratio device for an internal combustion engine, one described in Patent Document 1 below is known.

  The variable compression ratio device includes a link mechanism connecting a piston and a crankshaft by an upper link and a lower link, a connection mechanism connecting the link mechanism by a plurality of link members and the like, driving the connection mechanism, and a speed reduction mechanism And an actuator comprising a drive motor.

  One end of the connection mechanism is rotatably connected to one end of the lower link by a connection pin, and the other end is rotatably connected to the first control shaft via the first eccentric shaft and the first arm. A control link, and a connecting link whose one end is connected to the first control shaft via the second eccentric shaft portion and the second arm and whose other end is connected to the second control shaft via the link arm; Is equipped.

  The second control shaft is rotatably supported in the housing via a plurality of journals and is rotationally driven by an actuator. The actuator is controlled to rotate by a control current output from a control unit that detects an engine operating state.

  The second control shaft is rotationally driven by the rotational driving force output from the actuator, and the attitude of the lower link is controlled via the link arm, the connection link, the first control shaft, and the control link. The stroke characteristics are changed to control the actual compression ratio of the engine.

JP, 2011-169152, A

  However, in the actuator of the conventional variable compression ratio device, since the second control shaft and the link arm are integrally coupled, an excessive control current is output from the control unit and a drive motor is required. When the above rotational torque is generated, an excessive load may be applied to the entire multilink piston-crank mechanism including the connection mechanism from the second control shaft via the link arm, which may lead to a decrease in durability.

  The present invention has been made in view of the above-described conventional technical problems, and when an excessive rotational torque is generated on the second control shaft by the actuator, the second control shaft slips at the connection point of the link arm. An object of the present invention is to provide a variable compression ratio device of an internal combustion engine capable of absorbing excessive torque by generating rotation and suppressing deterioration in durability of each link member such as a connection mechanism.

In the present invention, among other things, the coupling mechanism includes a control link whose one end is rotatably coupled to the lower link, and a first one rotatably coupled to the other end of the control link via a first arm. a control shaft, a connection link having one end connected through the second arm portion on the first control shaft, a link arm rotatably connected to the other end of the connecting link, is formed in the housing were together is rotatably supported in the support hole, and a second control shaft coupled, the second control shaft is rotated by press-fitting the press-fit hole formed in the link arm, said link An actuator for transmitting a rotational driving force to the arm;
Equipped with
The second control shaft has a journal portion formed on the rear end side in the axial direction, and a fixing portion formed on the central side in the axial direction and press-fit into the press-fit hole,
Between the journal portion and the fixing portion, there is a step portion that restricts the movement of the link arm toward the journal portion when the fixing portion of the second control shaft is press-fit into the press-fitting hole. It is characterized by being formed .

  According to the present invention, even if an excessive rotational torque is applied from the actuator to the second control shaft, it is possible to suppress the decrease in the durability of the link mechanism and the connection mechanism.

FIG. 1 is a schematic view schematically illustrating an embodiment of a variable compression ratio device according to the present invention. It is a perspective view which disassembles and shows a part of coupling mechanism and actuator which are provided to the variable compression ratio apparatus of this embodiment. It is a top view of a part of said connection mechanism, and an actuator. It is a longitudinal cross section of a part of the connection mechanism, and an actuator. It is sectional drawing which shows the state connected by press injection of the 2nd control axis and link arm in this embodiment. It is sectional drawing which shows the state which the link arm has contact | abutted to the 1st stopper part by the excessive rotational torque of the 2nd control axis in this embodiment. It is a conceptual diagram which shows the absolute value which determines the setting range of compression ratio control by the control unit of this embodiment, and a setting range. It is a characteristic view showing the correlation between the slip torque and press fit interference between the 2nd control axis and link arm which are provided to this embodiment.

Hereinafter, an embodiment of a variable compression ratio device for an internal combustion engine according to the present invention will be described based on the drawings. In this embodiment, a variable compression ratio device (VCR) capable of changing the mechanical compression ratio is applied to an in-line four-cylinder internal combustion engine of gasoline specification.
First Embodiment
FIG. 1 schematically describes the variable compression ratio device of the present invention, which is the same as that described in FIG. 1 of Japanese Patent Application Laid-Open No. 2011-169152 cited above as the prior art, and thus, explain.

  That is, a link mechanism 01 connecting the piston 1 and the crankshaft 4 reciprocating in the cylinder of the cylinder block of the internal combustion engine, a connection mechanism 02 controlling the posture of the link mechanism 01, a speed reduction mechanism 21 and a drive motor described later And an actuator for rotationally driving the connection mechanism 02.

  The link mechanism 01 includes an upper link 3 whose upper end is rotatably connected to the piston pin 2 of the piston 1 and a lower link 5 rotatably connected to the crank pin 4 a of the crankshaft 4 There is. One end portion of the lower link 5 is rotatably connected at the lower end of the upper link 3 via a connection pin 6.

  The connection mechanism 02 is connected to the control link 7 provided to each cylinder whose one end is rotatably connected to the other end of the lower link 5 via the connection pin 8 and to the other end of the control link 7 The first control shaft 10 and the second control shaft 14 rotatably connected to the first control shaft 10 via the connection link 12 and the link arm 13 are provided.

  The first control shaft 10 extends in the cylinder row direction inside the engine parallel to the crankshaft 4 and is rotatably supported by the engine main body with a first journal portion 10a and a lower end of each control link 7 of each cylinder A plurality of first eccentric shaft portions 10b to which portions are rotatably mounted, and a second eccentric shaft portion 10c to which one end 12a of the connection link 12 is rotatably mounted.

  The first eccentric shaft portion 10b is provided at a position eccentrically with respect to the first journal portion 10a by a predetermined amount via the first arm portion 10d, while the second eccentric shaft portion 10c is provided with a second arm portion 10e. The first journal portion 10a is provided at a position eccentric to the first journal portion 10a by a predetermined amount.

  The connecting link 12 is formed in a lever shape, as shown in FIGS. 2 and 5, while the one end 12a connected to the second eccentric shaft 10c is formed substantially straight. The other end 12b to which the link arm 13 is connected is bent in a substantially curved shape. An insertion hole 12c through which the second eccentric shaft portion 10c is rotatably inserted is formed at the tip end of the one end 12a. On the other hand, in the other end 12b, a projection 13b (described later) of the link arm 13 is held between the bifurcated tip portions 12d and 12d, and is connected to the projection 13b. Fixing holes 12e and 12e through which the connecting pin 11 is press-fitted and fixed are formed through.

  The link arm 13 is formed separately from the second control shaft 14 and is entirely formed of iron-based metal in a thick raindrop annular shape, and the second control shaft 14 is formed at the center position of the annular main body 13a. A press-fit hole 13c press-fitted and fixed to a fixed portion formed between each of the front and rear journals is formed through, and a U-shaped protrusion projecting in the radial direction is formed on the outer periphery of the main body 13a. 13b is integrally provided. A connecting hole 13d in which the connecting pin 11 is rotatably supported is formed in the projecting portion 13b, and an axial center (connecting pin 11) of the connecting hole 13d is through the projecting portion 13b. A predetermined amount of eccentricity is made in the radial direction from the axis of the second control shaft 14.

  The second control shaft 14 is rotatably supported in a housing 20 described later via a plurality of journals, and is connected to the other end 12 b of the connection link 12 via a link arm 13. .

  Specifically, as shown in FIGS. 2 and 4, the second control shaft 14 is integrally formed with a shaft main body 23 integrally formed of iron-based metal and a rear end portion of the shaft main body 23. And a fixing flange 24 provided on the The shaft portion main body 23 is formed in a step diameter shape in the axial direction, and the small diameter first journal portion 23a on the tip end side, and the link arm 13 from the first journal portion 23a side via the press-fit hole 13c. It has an intermediate diameter fixed portion 23b on the central portion side to be press-fitted and a large diameter second journal portion 23c on the fixing flange 24 side. Further, a first stepped portion 23d is formed between the fixed portion 23b and the second journal portion 23c, and a second stepped portion 23e is formed between the first journal portion 23a and the fixed portion 23b. Is formed.

When the first step portion 23d press-fits the press-fit hole 13c of the link arm 13 into the fixed portion 23b from the first journal portion 23a side, one side hole of the press-fit hole 13c on the second journal portion 23c side It abuts the edge in the axial direction to restrict movement of the link arm 13 in the direction of the second journal portion 23c. Meanwhile, the second stepped portion 23e, when inserted through the shaft body 23 to the support hole 30, so as to regulate the movement in the axial direction in contact with the later-described step hole edge 30c of the support hole 30 .

  The fixing flange 24 has six bolt insertion holes 24a formed at equal intervals in the circumferential direction on the outer peripheral portion, and the thrust plate 26 is formed by six bolts 25 inserted through the bolt insertion holes 24a. It is coupled to a circular spline 27 which is an internal gear of the reduction gear 21.

  The second control shaft 14 is changed in rotational position by the rotational force transmitted from the drive motor 22 via the reduction gear 21 which is a part of the actuator, and the second control shaft 14 is connected via the connection link 12 or the like. (1) The control shaft 10 rotates and the position of the lower end of the control link 7 moves. As a result, when the attitude of the lower link 5 changes, the engine compression ratio changes as the stroke characteristic of the piston 1 changes.

  As shown in FIGS. 2 to 4, the actuator includes a housing 20 rotatably supporting the second control shaft 14 and the like therein, and a speed reducer 21 provided inside the rear end side of the housing 20. A drive motor 22 mounted on the rear end side of the reduction gear 21 and a control unit 58 which is an electronic controller for controlling forward and reverse rotation of the drive motor 22 by a control current are mainly included.

  The housing 20 is formed substantially in a cube as a whole by an aluminum alloy material, and a large-diameter annular opening groove 28a is formed inside the rear end side (drive motor 22 side), and the opening groove 28a is formed. An annular storage chamber 28b is formed on the front side than the inner side.

  The opening groove portion 28a is for accommodating and arranging the reduction gear 21 mainly inside, and a step circle for inserting and arranging the shaft portion main body 23 of the second control shaft 14 in the inner axial direction from the center position of the bottom surface A columnar support hole 30 is formed to penetrate along the axial direction so as to be orthogonal to the storage chamber 28b.

  The accommodation chamber 28b accommodates and arranges a connection portion between the other end 12b of the control link 12 and the link arm 13 by the connection pin 11, as shown in FIGS. Is formed in a space that ensures free swinging of the control link 12 and the link arm 13, and the width length is formed slightly larger than the width of the other end 12b of the control link 12 during operation I'm suppressing the play.

  As shown in FIG. 4, the support hole 30 is formed in a step diameter shape so that the outer diameter of the inner peripheral surface matches the outer diameter of the shaft portion main body 23 of the second control shaft 14, and the first journal portion 23a Of the small diameter first bearing hole 30a in which the bearing is supported, a position corresponding to the fixed portion 23b, that is, a portion opened in the accommodation chamber 28b, and a large diameter second bearing hole in which the second journal portion 23c is bearing And 30b.

  When the second shaft portion main body 23 is inserted into the support hole 30, the stepped hole edge 30c of the first bearing hole 30a facing the accommodation chamber 28b is in contact with the second stepped portion 23e from the axial direction and is longer than that Is designed to regulate the insertion of The maximum insertion movement position control of the shaft portion main body 23 with respect to the support hole 30 is also performed by bringing the inner peripheral portion of the fixing flange 24 into contact with the outer hole edge of the second bearing hole 30b. There is.

  Further, the opening end of the opening groove portion 28 a is closed by the cover 29 via the O-ring 51. In the cover 29, a motor shaft insertion hole 29a is formed at a central position, and bolt insertion holes are formed in the four bosses 29b protruding in the radial direction on the outer peripheral surface. The hole 20 is fixed to the housing 20 by four bolts 43 inserted from the drive motor 22 side.

  An angle sensor 32 for detecting the rotational angle position of the second control shaft 14 is housed and disposed in the small diameter holding hole 31 axially extended from the support hole 30. As shown in FIGS. 2 and 4, the angle sensor 32 has a cap-shaped sensor cover 32a press-fitted and fixed to the inner peripheral surface of the holding hole 31, and an angle disposed on the inner peripheral side of the sensor cover 32a. A detection rotor 32b and a sensor portion 32c provided at the center of the sensor cover 32a for detecting the rotational position of the rotor 32b are mainly configured.

  The sensor cover 32 a is sealed between the sensor cover 32 and the holding hole 31 by a gasket 33, and is attached to the housing 20 together with the sensor portion 32 c by two bolts 34. Further, two O-rings 35 are provided on the outer periphery of the cylindrical portion of the sensor cover 32a, thereby restricting the entry of oil in the direction of the sensor portion 32c.

  The rotor 32 b has a rear end side protrusion 32 d press-fitted and fixed in a fixing hole formed inside the front end side of the shaft portion main body 23. The sensor unit 32c is configured to output a detected signal to a control unit 58 described later that detects an engine operating state.

  The housing 20 is connected to cooling water pipes 44a and 44b for supplying and discharging the cooling water for cooling the angle sensor 32 to the inside.

  The reduction gear 21 is a harmonic drive (registered trademark) type, and is accommodated in the opening groove 28 a of the housing 20 in which each component is closed by the cover 29. That is, the first circular spline 27 in an annular shape is fixed to the fixing flange 24 of the shaft portion main body 23 by bolts and has a plurality of inner teeth 27 a formed on the inner periphery, and the inside of the first cure spline 27. A flexible deformable flex spline 36 which is an external gear that is disposed and has a plurality of external teeth 36 a meshing with the respective internal teeth 27 a on the outer circumferential surface, and an outer peripheral surface formed in an elliptical shape A wave generator 37, which is a wave generator sliding along a portion of the circumferential surface, and an inner tooth 38a disposed on the outer circumferential side of the flex spline 36 and meshed with each outer tooth 36a on the inner circumferential surface The second circular spline 38 is mainly composed of:

  The first circular spline 27 is formed with six female screw holes 27b into which the bolts 25 at equally spaced positions in the circumferential direction are screwed.

  The flex spline 36 is formed in a thin-walled cylindrical shape that can be bent and deformed by a metal material, and the number of teeth of each of the external teeth 36 a is the same as the number of teeth of each of the internal teeth 27 a of the first circular spline 27. .

  The wave generator 37 is formed in a substantially annular shape, and a through hole 37a of a relatively large diameter is formed at the center, and a plurality of internal teeth 37b are formed on the inner peripheral surface of the through hole 37a. Further, the wave generator 37 is provided by front and rear ball bearings 39, 40 provided between a cylindrical portion projecting in the axial direction from the front and rear hole edge of the through hole 37a and the fixing flange 24 and the cover 29. It is rotatably supported. The wave generator 37 has a flat outer peripheral surface and is in sliding contact with the flat inner peripheral surface of the flex spline 36.

  In the second circular spline 38, six bolt insertion holes are formed through the flange 38b on the outer peripheral side, and a second thrust is applied to the inner end of the cover 29 by six bolts 41 inserted through the respective bolt insertion holes. It is fixed via a plate 42. Further, the number of teeth of each of the internal teeth 38a of the second circular spline 38 is two more than the number of the external teeth 36a of the flex spline 36. Accordingly, the number of teeth is two more than the number of teeth of each internal tooth 27a of the first circular spline 27. The speed reduction ratio is determined by such a difference in the number of teeth.

  The drive motor 22 is a brushless type electric motor, and as shown in FIGS. 2 and 4, a cylindrical motor casing 45 with a bottom and a cylindrical shape fixed to the inner peripheral surface of the motor casing 45 A coil 46, a magnet rotor 47 rotatably provided inside the coil 46, and a motor shaft 48 having one end 48a fixed at the axial center of the magnet rotor 47 are mainly included.

  The motor casing 45 is attached to the rear end portion of the cover 29 through an O-ring 50 by four bolts 49 inserted through bolt insertion holes 45b provided in four bosses 45a formed on the outer periphery of the front end. Further, on the outer periphery of the motor casing 45, a connector portion 67 for inputting a control current from the control unit is integrally provided.

  In the magnet rotor 47, positive and negative magnetic poles are alternately arranged in the circumferential direction on the outer periphery, and a fixing hole 47a to which one end portion 48a of the motor shaft 48 is press-fitted and fixed is formed at the center of the shaft. There is.

  The motor shaft 48 is supported by a ball bearing 52 whose outer ring is fixed in the end wall of the motor casing 45 while the tip end of one end 48a protruding from one end face of the magnet rotor 47 is supported by the other end 48b The outer ring is supported by a ball bearing 53 fixed to the inner periphery of the motor shaft insertion hole 28 a of the cover 29. Further, on the outer peripheral surface of the other end portion 48b, an external tooth 48c with which the internal tooth 37b of the wave generator 37 is engaged is formed.

  The ball bearing 53 is held in the holding groove of the cover 29 by a screw 55 via a substantially disc-like retainer 54.

  A resolver 55 for detecting the rotational angle of the motor shaft 48 is disposed substantially at the center of the motor shaft 48 in the axial direction. The resolver 55 includes a resolver rotor 55a press-fitted and fixed to the outer periphery of the motor shaft 48, and a sensor portion 55b for detecting a multi-leaf target formed on the outer peripheral surface of the resolver rotor 55a. The sensor unit 55b is fixed to the inside of the cover 29 by two screws 56, and outputs a detection signal to the control unit 58.

  Further, in the inner axial direction and the radial direction of the second control shaft 14, an introducing portion for introducing lubricating oil pumped from an oil pump (not shown) and a radial direction hole 65 communicating with the introducing passage are formed. There is. The introduction portion is formed at the center of the fixing flange 24 and is provided with a conical oil chamber 64a to which lubricating oil is supplied from an oil hole not shown, and an inner axial center of the second control shaft 14 from the oil chamber 64a. And an axial hole 64b formed along the direction.

  An inner end of the radial hole 65 is formed at the tip of the axial hole 64b, and an outer end of the radial hole 65 is opened at the clearance between the outer peripheral surface of the first journal portion 23a and the first bearing hole 30a. Lubricating oil is supplied here.

  The control unit 58 detects the current engine operating condition based on information signals from various sensors such as a crank angle sensor, an engine load sensor, a water temperature sensor, a throttle valve opening sensor, etc. It performs engine control such as ignition timing.

  Further, the control unit 58 processes the current rotation angle position of the second control shaft 14 by the angle sensor 32 and the current rotation angle position of the motor shaft 58 by the resolver 55 to the drive motor 22. By outputting the control current, the drive motor 22 is controlled in forward and reverse directions to variably control the actual compression ratio of the piston 1 to a low compression ratio-high compression ratio.

  When the link arm 13 is turned counterclockwise by the second control shaft 14 as shown in FIGS. 5 and 6, the inner wall surface of the housing 20 which forms the storage chamber 28b is: A first stopper portion 57, which is a stopper on one side that regulates the maximum rotational position of the link arm 13, is provided.

  The first stopper portion 57 is formed by forming the lower portion of the inner wall surface forming the storage chamber 28b in an inclined surface shape, and one straight side surface 13e of the projection portion 13b of the link arm 13 abuts on the link One maximum rotation position of the arm 13 is regulated.

  The maximum pivoting position on one side of the link arm 13 is a position at which the compression ratio is lower than the normal low compression ratio position of the piston 1 controlled by the control unit 58 via the drive motor 22 etc. The position is not controlled by the control unit 58.

  On the other hand, on the side of the first control shaft 10, a second stopper portion (not shown) that restricts further rotation of the first control shaft 10 to a position where the compression ratio is higher than the high compression ratio position of the piston 1 The maximum rotational position of the other side of the first control shaft 10, whose rotation is restricted by the second stopper portion, is controlled by the control unit 58 via the drive motor 22 or the like. It is a position where the compression ratio is higher than the specific position, and this position is not controlled.

  That is, as shown in FIG. 7, the control range of the low compression ratio and high compression ratio of the piston 1 by the control unit 58 is the rotation angle of the second control shaft 14 in which the link arm 13 is restricted by the first stopper portion 57. The position is set to 0 on the low compression ratio side, and the rotation angle position of the second control shaft 14 whose rotation is restricted by the second stopper portion is set to the absolute value 0 'on the high compression ratio side. The compression ratio control is performed within the setting range X (normal control range) of the target compression ratio that is within the rotation range Y and the angle between the absolute values 0, 0 'is the rotation range Y. It has become. As a result, even under the operating conditions under which the maximum or minimum compression ratio is set as the target compression ratio, it is sufficient to rotate the second control shaft 14 to the rotation angle before coming into contact with any stopper portion. It is set.

  The friction force between the outer peripheral surface of the fixed portion 23b of the second control shaft 14 and the inner peripheral surface of the press-fitting hole 13c of the link arm 13 to which the outer peripheral surface is press-fitted is determined by the drive motor 22. When a predetermined rotational torque (preferably, the maximum rotational torque of the drive motor 22) is applied to the second control shaft 14, it is set so as to slide and rotate for the first time between the two 23b and 13c.

  That is, an erroneous overcurrent is temporarily output from the control unit 58 to the drive motor 22, and the drive motor 22 is further driven to rotate in one direction out of the setting range X of the target compression ratio, as shown in FIG. Thus, the link arm 13 is synchronized with the link arm 13 from the P position in FIG. 6 where the link 13 is synchronously rotated in the same direction and the projection 13b abuts against the stopper 57 of the housing 20 to restrict further rotation. When a rotational torque in the direction (arrow direction) is applied, the fixed portion 23b of the second control shaft 14 is slipped, rotated and idled to the position Q in FIG. 6 in the press-fitting hole 13c.

  The relationship between the slip rotation torque (slip torque) and the frictional force (press-in interference) between the outer peripheral surface of the fixed portion 23b of the second control shaft 14 and the inner peripheral surface of the press-fit hole 13c of the link arm 13 is It is set as shown in FIG. That is, with normal rotational torque by the drive motor 22, no slip rotation (slip) occurs between the inner peripheral surface of the press-fitting hole 13c and the outer peripheral surface of the fixed portion 23b, and the fastening state of both 13 and 23 Is held (holding torque), but the operation of the drive motor 22 becomes abnormal due to the excessive control current from the control unit 58, and an excessive rotational torque in one direction is generated. When the compression ratio setting range X is overshooted to abut against the stopper portion 57 and a rotational torque is applied, a slip is generated between the two 13 and 23.

[Operation of this embodiment]
According to this embodiment of the above configuration, the second control shaft 14 and the link arm 13 are separately formed, and the link arm 13 is coupled to the shaft main body 23 in the accommodation chamber 28 b. Thus, it is not necessary to form the inner diameter of the motor shaft insertion hole 30 of the housing 20 large to allow the link arm 13 to be inserted, as in the case where both 23 and 13 are integrally formed. There is no need to split up and down at all.

  Therefore, the enlargement of the entire housing 20 is suppressed, and the downsizing and weight reduction of the housing 20 can be achieved. As a result, the mountability of the variable compression ratio device to the engine is improved.

  Also, by making the second control shaft 14 and the link arm 13 separate, the degree of freedom of the length of the link arm 13 is improved, and the length can be set according to the size of the storage chamber 28b. It is possible to reduce the reverse input load from the control link 12 to the second control shaft 14 side. Thereby, the load on the reduction gear 21 and the drive motor 22 can be reduced.

  Moreover, in the present embodiment, an excessive control current is temporarily output from the control unit 58 to the drive motor 22, causing the drive motor 22 to malfunction, for example, generating an excessive rotational torque in one direction. The link arm 13 abuts on the first stopper portion 57 beyond the setting range X of the target compression ratio on the low compression ratio side by the generation of an excessive rotational torque in one direction on the second control shaft 14 (absolute value (absolute value 0) After that, if a rotational torque equal to or more than a predetermined value is applied, the outer peripheral surface of the fixed portion 23b of the second control shaft 14 slips in the press-fit hole 13c of the link arm 13 and excessive rotational torque is absorbed. Be done.

  For this reason, generation | occurrence | production of the big load with respect to the connection mechanism 02 below the link arm 13 or the link mechanism 01 whole is suppressed. As a result, the reduction in durability of the link mechanism 01 and the connection mechanism 02 can be suppressed.

  On the other hand, when an excessive rotational torque in the other direction of the drive motor 22 is transmitted to the second control shaft 14 by the control current from the control unit 58, this rotational torque is transmitted via the link arm 13 or the connecting link 12. When the torque is transmitted to the first control shaft 10 and its rotation is restricted by the second stopper (absolute value 0 ') and an excessive rotational torque is applied, the second control shaft 14 and the link arm 13 are again operated in this case. Slips between them and absorbs excessive torque. As a result, the occurrence of a large load on the coupling mechanism 02 and the link mechanism 01 is similarly suppressed.

  Further, as described above, the link arm 13 abuts on the first stopper portion 57 beyond the setting range X of the target compression ratio, or the first control shaft 10 is restricted by the second stopper portion from further rotation. When the second control shaft 14 slips in the forward rotation or reverse rotation direction in the press-fit hole 13c, the control unit 58 is operated on the low compression ratio side or the high compression ratio side from the angle sensor 32. If the rotation angle of the second control shaft 14 at one of the absolute values 0 and 0 'is deviated from the predetermined rotation angle (reference rotation angle) by a predetermined amount or more, it is determined that the slip state has occurred. The rotation control of the drive motor 22 is stopped. Then, the piston 1 is pushed down by the combustion pressure of the combustion chamber and mechanically changed to the low compression ratio side. For this reason, it will be in the driving | running state which can avoid generation | occurrence | production of a knocking.

  Further, as described above, when the control unit 58 determines that the second control shaft 14 is slipping at the press-fit hole 13c of the link arm 13, the control unit 58 temporarily stops the rotation control of the drive motor 22. Thereafter, after a predetermined time has elapsed, a control current is output to the drive motor 22 to separate the link arm 13 from the first stopper portion 57 via the second control shaft 14. Thereafter, the link arm 13 is again brought into contact with the first stopper portion 57, whereby the absolute value 0 of the second control shaft 14 is detected again from the angle sensor 32, and based on this rotational angle position and the original rotational angle position. Thus, the displacement of the rotational position of the second control shaft 14, that is, the displacement of the compression ratio due to the slip is detected.

  As a result, the control unit 58 restores the normal rotation control of the drive motor 22 from the slipping state of the second control shaft 14, and then performs the initialization operation. That is, the drive motor 22 is controlled to rotate by a normal control current, and the link arm 13 is brought into contact with the first stopper portion 57 to detect the absolute values 0 and 0 'which are the rotation angles of the second control shaft 14 And set the reference rotation angle based on the absolute value 0, 0 '. Thereafter, normal actual compression ratio control is performed via the coupling mechanism 02 and the link mechanism 01.

  Also, when the second control shaft 14 generated by the excessive rotational torque of the drive motor 22 mentioned above is slidingly rotating, and at the same time, the current actual compression ratio by the control unit 58 becomes undetectable. The rotation control of the drive motor 22 by the control unit 58 is stopped. As a result, the actual compression ratio is mechanically changed to the low compression ratio side by depression of the piston 1 by the combustion pressure, and failsafe control is performed.

  Further, in the present embodiment, the diameter of the shaft main body 23 is reduced stepwise from the second journal portion 23c having the largest diameter to the fixed portion 23b having the medium diameter and the first journal portion 23a having the smallest diameter. Thus, the insertability into the support hole 30 is improved.

  Further, since the link arm 13 is press-fit and coupled in the axial direction with the fixing portion 23b of the shaft portion main body 23 through the press-fitting hole 13c, the connection work of both 13 and 23 becomes easy.

  Further, by bringing the second step portion 23e of the shaft portion main body 23 into contact with the step hole edge 30c of the support hole 30, positioning in the axial direction when the shaft portion main body 23 is inserted becomes easy. Since the position control of the link arm 13 in the axial direction can be performed at the time of press-fitting by utilizing the first step portion 23d of the above, positioning is facilitated also at this point.

  Furthermore, since the shaft main body 23 is supported by the two front and rear first and second bearing holes 30a and 30b of the support hole 30 via the front and back two first and second journals 23a and 23c, 2) It becomes possible to always support the control shaft 14 stably.

  Further, while the shaft body 23 of the second control shaft 14 is formed of iron-based metal, the entire housing 20 including the first and second bearing holes 30a and 30b is formed of an aluminum alloy material, and the first bearing Since the hole 30a is formed in a small diameter, the difference between iron and aluminum alloy due to thermal expansion and contraction is reduced, thereby generating a runout due to rattle between the first journal portion 23a and the first bearing hole 30a. It can be suppressed.

  The present invention is not limited to the configuration of the embodiment, and, for example, the second stopper portion for restricting the maximum rotational position of the first control shaft 10 is the same as the first stopper portion 57 as the accommodation chamber of the housing 20. It is also possible to contact the opposite side of the projection 13 b of the link arm 13 by providing it at a position opposite to the first stopper portion 57 of 28 b.

  Further, as a structure of each of the stopper portions, a stopper pin may be provided on the inner wall surface of the housing 20 accommodation chamber 28b, and the projection 13b of the link arm 13 may be made to abut on this stopper pin.

DESCRIPTION OF SYMBOLS 01 ... Link mechanism 02 ... Connection mechanism 1 ... Piston 3 ... Upper link 4 ... Crankshaft 5 ... Lower link 7 ... Control link 10 ... 1st control axis 10d ... 1st arm part 10e ... 2nd arm part 12 ... Connection link 12a ... one end 12b ... the other end 13 ... link arm 13a ... main body 13b ... projection 13c ... hole for press fit 14 ... second control shaft 20 ... housing 21 ... reduction gear 22 ... drive motor 23 ... shaft section main body 23a ... first Journal portion 23b: Fixing portion 23c: Second journal portion 28a: Opening groove portion 28b: Storage chamber 29: Cover

Claims (8)

The piston of the engine and the crankshaft are connected by the lower link and the upper link of the link mechanism, and the posture of the lower link is controlled by the actuator via the connection mechanism to change the stroke characteristics of the piston to change the engine A variable compression ratio device for an internal combustion engine that controls a compression ratio, comprising:
The coupling mechanism is
A control link whose one end is rotatably connected to the lower link;
A first control shaft rotatably connected to the other end side of the control link via a first arm;
A connecting link whose one end is connected to the first control shaft via a second arm;
A link arm rotatably coupled to the other end of the coupling link;
With and is rotatably supported by a support hole formed in the housing, and a second control shaft coupled by press-fitting the press-fit hole formed in the link arm,
An actuator for rotationally driving the second control shaft to transmit a rotational driving force to the link arm;
Equipped with
The second control shaft has a journal portion formed on the rear end side in the axial direction, and a fixing portion formed on the central side in the axial direction and press-fit into the press-fit hole,
Between the journal portion and the fixing portion, there is a step portion that restricts the movement of the link arm toward the journal portion when the fixing portion of the second control shaft is press-fit into the press-fitting hole. A variable compression ratio device for an internal combustion engine, characterized in that it is formed . In the variable compression ratio device for an internal combustion engine according to claim 1,
A variable compression ratio device for an internal combustion engine, comprising: a stopper that regulates a maximum rotational position of the link arm. In the variable compression ratio device for an internal combustion engine according to claim 2,
In a state in which the link arm is in contact with the stopper rotates in one direction, when the maximum torque of the actuator acts on the second control shaft, the press-fit hole of the second control shaft is the link arm A variable compression ratio device for an internal combustion engine, characterized by sliding against. In the variable compression ratio device for an internal combustion engine according to claim 2,
An angle sensor for detecting the rotational position of the second control axis is provided, and an electronic controller for controlling the actuator in accordance with the rotational angle position detected by the angle sensor is provided.
After engine startup, when the link arm is in contact with the stopper, that rotation angle of the second control shaft is shifted relative to the predetermined rotational angle when detecting said angle sensor, the electronic A variable compression ratio device for an internal combustion engine, wherein a controller determines that the second control shaft is slidingly rotating with respect to the link arm. In the variable compression ratio device for an internal combustion engine according to claim 4,
When the electronic controller determines that the second control shaft is slidingly rotating with respect to the link arm, the control of the actuator by the electronic controller is stopped to utilize the actual compression ratio of the engine using the combustion pressure A variable compression ratio device for an internal combustion engine, which is mechanically reduced by the In the variable compression ratio device for an internal combustion engine according to claim 4,
Said electronic controller is spaced when the link arm is determined that contact with the stopper rotating sliding the second control shaft relative to the link arm, said link arm by controlling the actuator from the stopper After that, by making the link arm abut against the stopper again, the amount of deviation from the actual compression ratio is detected based on the rotation angle detection information from the angle sensor, and the variable compression ratio device of the internal combustion engine . In the variable compression ratio device for an internal combustion engine according to claim 6,
When the detection impossible state of the actual compression ratio by the electronic controller occurs simultaneously with the sliding rotation state of the second control shaft, the control of the actuator by the electronic controller is stopped, and the actual compression ratio of the engine is A variable compression ratio device for an internal combustion engine, which is mechanically reduced using combustion pressure. In the variable compression ratio device for an internal combustion engine according to claim 6,
It said after returning to the normal control state with respect to the actuator by the electronic controller from a second state where the control shaft is sliding rotation, is brought into contact with the link arm to the stopper, and the link arm and the stopper A variable compression ratio device for an internal combustion engine, wherein a rotation angle of the second control shaft in an abutting state is set to a reference rotation angle.

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