JP4252996B2 - Variable compression ratio device for internal combustion engine - Google Patents

Description

  The present invention relates to a compression ratio variable device for an internal combustion engine, and in particular, a piston inner connected to a connecting rod via a piston pin, and a piston inner while being connected to the piston inner and having an outer end face facing a combustion chamber. And a piston outer that can move between a low compression ratio position close to the combustion chamber and a high compression ratio position close to the combustion chamber. The piston outer is operated to a low compression ratio position to lower the compression ratio of the engine and to a high compression ratio position. It is related to the improvement of the one that is operated to increase the compression ratio.

Such a variable compression ratio device for an internal combustion engine is already known as disclosed in Patent Documents 1, 2, and 3 below.
JP-A-11-117779 USP 5,476,074 Patent Specification JP 2005-54691 A

  By the way, the device disclosed in Patent Document 1 is such that the piston outer is screwed onto the outer periphery of the piston inner, and the piston outer is moved forward and backward with respect to the piston inner by rotating forward and backward. In this case, in order to operate the piston outer to the low compression ratio position and the high compression ratio position, it is necessary to rotate the piston outer. Can not be set freely according to the ceiling surface shape of the combustion chamber and the arrangement of the intake and exhaust valves, and it is difficult to sufficiently increase the compression ratio of the engine at a high compression ratio position.

  The device of Patent Document 2 is such that the piston outer can move between a low compression ratio position near the piston inner and a high compression ratio position near the combustion chamber along the axial direction with respect to the piston inner. A flange formed on the outer periphery of the piston inner and having a wall thickness smaller than the width of the annular groove is slidably fitted in the circumferential groove formed on the inner periphery of the outer, and the flange is formed on the groove. At the low compression ratio position of the outer piston that is in contact with the upper surface, a pair of arc-shaped first latch plates attached to the piston inner expand radially and engage the piston outer to lock the outer piston. At the high compression ratio position of the outer piston where the flange abuts the lower surface of the groove, a pair of arc-shaped second latch plates that are also attached to the piston inner are radially extended to extend the pin. The outer piston is locked by engaging with the ton outer. In this device, a pair of arc-shaped first and second latch plates are arranged on the same plane in the circumferential direction of the piston inner. Therefore, when the first or second latch plate is in operation, the load that the latching part of the pair of latch plates bears due to the pressure in the cylinder and the inertial force acting on the piston, and durability against that load is increased. In order to increase it, the weight of the piston must be increased.

  Further, the device of Patent Document 3 is provided with a regulating means provided between a piston inner and a piston outer, which are slidably fitted in each other in an axial direction, to regulate the amount of movement in the axial direction, and a head portion between the piston inner and the piston outer. A first cam mechanism interposed between them and controlling a first axial distance therebetween, and a second cam mechanism interposed between a piston inner and the restricting means to control an axial distance therebetween. In this device, the first and second cam mechanisms are stacked in the axial direction of the piston so as to extend over the entire circumference of the piston. Although easy, it is difficult to reduce the piston size and weight.

  The present invention has been made in view of such circumstances, and can be operated to a low compression ratio position and a high compression ratio position without rotating the piston outer, and can be made compact, lightweight, and durable. An object of the present invention is to provide a variable compression ratio device for an internal combustion engine.

  In order to achieve the above object, a variable compression ratio device for an internal combustion engine according to the present invention includes a piston inner coupled to a connecting rod via a piston pin; and is fitted to the outer periphery of the piston inner so as to be slidable only in the axial direction. A piston outer that can move between the low compression ratio position near the piston inner and the high compression ratio position near the combustion chamber, with the outer end face facing the combustion chamber; interposed between the piston inner and the outer A lift release position that allows the piston outer to move to a low compression ratio position, and a lift member that can move between lift positions that hold the piston outer at a high compression ratio position; the lift member at the lift release position and the lift position; A first actuator that operates between the piston inner and the piston outer, and is fixed when the piston outer reaches a low compression ratio position. A locking mechanism that prevents relative movement of the inner and piston outer in the axial direction. The locking mechanism includes an axial female spline formed on the inner peripheral surface of the piston outer, and a groove portion of the female spline. And a male spline corresponding to the female spline on the outer periphery. When the piston outer is at the high compression ratio position (H), the male spline is connected to the female spline. When the piston outer is in the low compression ratio position, the male spline enters and rotates into the lock groove to prevent sliding with respect to the female spline. The lock plate is attached to the piston inner so as to occupy the lock position, and the lock plate includes the lock release position and the lock plate. That connects the second actuator for operating the location and the first feature.

  According to the present invention, in addition to the first feature, a shaft portion connected to both ends of the piston pin is fitted into a long hole formed in the piston outer and having a long diameter in the axial direction. The second feature is that relative rotation of the piston inner and the piston outer is prevented.

  Furthermore, in addition to the second feature, the present invention regulates the movement limit of the piston outer toward the high compression ratio position side by bringing the shaft portion into contact with the lower end wall of the elongated hole. This is the third feature.

  In addition to the second feature of the present invention, the groove portion of the female spline is provided with a blocking portion that receives the tooth portion of the male spline and restricts the movement limit of the piston outer toward the high compression ratio position. This is the fourth feature.

  According to the first feature of the present invention, by alternately operating the lift member to the lift release position and the lift position, it is possible to control to the low compression ratio position and the high compression ratio position without rotating the piston outer. . At this time, in particular, an axial female spline formed on the inner peripheral surface of the piston outer is provided with a lock mechanism that prevents the relative movement of the piston inner and the piston outer in the axial direction when the piston outer reaches the low compression ratio position. A lock groove that communicates the upper end of the groove of the female spline with each other, and a male spline corresponding to the female spline on the outer periphery. When the piston outer is in the high compression ratio position, the male spline is connected to the female spline. When the piston outer is in the low compression ratio position, the male spline enters the lock groove and occupies a lock position where the sliding against the female spline is prevented. In this way, the lock plate is attached to the piston inner so that the load in the separation direction acting on the piston outer and piston inner The load can be distributed over the entire circumference of the mechanism, the durability of the lock mechanism can be improved, and the structure is simple and compact, making the piston more compact, lighter and more durable. it can.

  According to the second feature of the present invention, the relative rotation of the piston inner and the piston outer can be prevented with a simple structure.

  According to the third feature of the present invention, the movement limit of the piston outer to the high compression ratio position side can be regulated by utilizing the structure that prevents the relative rotation of the piston inner and the piston outer, and the structure is simplified. Can be achieved.

  According to the fourth feature of the present invention, the movement limit of the piston outer 5b to the high compression ratio position H side can be surely restricted by an extremely simple structure in which the closed portion is provided in the groove portion of the female spline.

  Embodiments of the present invention will be described below on the basis of preferred embodiments of the present invention shown in the accompanying drawings.

  FIG. 1 is a longitudinal sectional front view of an essential part of an internal combustion engine provided with a compression ratio variable device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the compression ratio variable device from above, and FIG. 4 is an exploded perspective view from below, FIG. 4 is an enlarged view of the main part of FIG. 1 (low compression ratio state), FIG. 5 is a sectional view taken along line 5-5 in FIG. 4, and FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5, FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 5, FIG. 9 shows a high compression ratio state, FIG. 10 is a sectional view taken along the line 11-11 in FIG. 10, FIG. 12 is a sectional view taken along the line 12-12 in FIG. 10, and FIG. 13 is a sectional view taken along the line 13-13 in FIG. 14 shows a high compression ratio state, a corresponding diagram with FIG. 13, FIG. 15 is an enlarged view of the auxiliary switching valve portion in FIG. 1 (low compression ratio state), and FIG. 16 shows a high compression ratio state. Correspondence figure, figure with FIG. 7 is a diagram showing a change in hydraulic pressure of the hydraulic actuator accompanying the operation of the auxiliary switching valve, FIG. 18 is an enlarged view of a portion 18 in FIG. 17, and FIG. 19 shows another embodiment of the present invention, corresponding to FIG. 20 is a cross-sectional view taken along line 20-20 in FIG.

  1 and 5, an engine body 1 of an internal combustion engine E includes a cylinder block 2 having a cylinder bore 2a, a crankcase 3 coupled to the lower end of the cylinder block 2, and a pent roof type combustion connected to the upper end of the cylinder bore 2a. The cylinder head 4 has a chamber 4a and is coupled to the upper end of the cylinder block 2. The cylinder head 4 opens and closes an intake port 30i and an exhaust port 30e that open on the ceiling surface of the combustion chamber 4a. An intake valve 31i and an exhaust valve 31e that are to be turned on, and a spark plug 32 that faces the electrode at the center of the combustion chamber 4a are screwed.

  A small end 7a of a connecting rod 7 is connected via a piston pin 6 to a piston 5 slidably fitted in the cylinder bore 2a, and a large end 7b of the connecting rod 7 is connected via a pair of left and right bearings 8 and 8. And connected to a crank pin 9a of a crank shaft 9 rotatably supported by the crank case 3.

  As shown in FIGS. 2 to 5, the piston 5 is slidably fitted to a piston inner 5a connected to a small end 7a of a connecting rod 7 via a piston pin 6 and an outer peripheral surface of the piston inner 5a. The piston outer 5b has a top surface facing the combustion chamber 4a, and a plurality of piston rings 10a to 10c that are slidably in close contact with the inner peripheral surface of the cylinder bore 2a are mounted on the outer periphery of the piston outer 5b. Is done.

  The piston inner 5a slides on the inner peripheral surface of the cylinder bore 2a except for a pair of pin boss portions 11, 11 supporting both ends of the piston pin 6 and a portion corresponding to the outer ends of the pin boss portions 11, 11. A pair of arc-shaped skirt portions 12 and 12 that are freely fitted are integrally formed. The piston pin 6 is hollow.

  On the other hand, the piston outer 5b ends the peripheral wall on which the piston rings 10a to 10c are mounted at a position facing the upper end surface 12a of the skirt portions 12 and 12. The piston outer 5b is integrally formed with a pair of ear portions 13, 13 that are opposed to the outer ends of the pin boss portions 11, 11. These are provided with long holes 14 and 14 having a long diameter in the axial direction of the piston 5, and the long holes 14 and 14 have both end portions of the extension shaft 15 penetrating through the hollow portion of the piston pin 6. The extension shaft 15 is slidably fitted along the axial direction of the piston 5 and is fixed to the piston pin 6 by press fitting or the like. Thus, by fitting the long holes 14 and 14 and the extension shaft 15, the piston inner 5a and the piston outer 5b are allowed to slide in the axial direction while being prevented from rotating relative to each other. 14, 14 is in contact with the lower surface of the piston 14, the lower sliding limit of the piston inner 5a relative to the piston outer 5b is regulated.

  A pair of inner sliding flat surfaces 23, 23 extending in the axial direction of the piston pin 5 are formed on both sides of the outer surface of the piston inner 5 a facing both end surfaces of the piston pin 6. , 23 are formed on the inner side surfaces of the ear portions 13, 13 of the piston outer 5b. The sliding flat surfaces 23, 24 are also formed on the piston inner 5a and the piston outer 5b. Relative sliding in the axial direction is allowed while preventing relative rotation. Therefore, the relative rotation of the piston inner 5a and the piston outer 5b is strengthened by the fitting between the long holes 14, 14 and the extension shaft 15 and the contact between the inner and outer sliding flat surfaces 23, 24. Can be blocked. As described above, the engagement structure between the long holes 14 and 14 and the extension shaft 15 and the contact structure of the inner and outer sliding flat surfaces 23 and 24 are used together to prevent the piston inner 5a and the piston outer 5b from rotating together. This is effective in reducing the load burden of each structure, improving wear resistance, and strengthening the anti-rotation rigidity between the piston inner 5a and the piston outer 5b. It is possible to adopt only one of these.

  2, 3 and 5, the piston inner 5a and the outer inner 5b are slidably fitted to the extension shaft 15 and the long holes 14, 14 and a pair of arcuate surfaces 33, 33 on the outer periphery of the piston inner 5a. In addition, a sufficient axial relative sliding support length is obtained by the slidable fitting of the inner peripheral surface 42a of the female spline 42 of the outer inner 5b, and stable axial relative sliding can be ensured. The circular arc surfaces 33, 33 are formed vertically so as to connect the upper end surfaces 12 a of the pair of skirt portions 12, 12 and the first support surface 17.

  As clearly shown in FIGS. 3 to 5, the upper part of the piston inner 5 a has an annular first support surface 17 that faces upward from the outer peripheral side, and a first pivot that stands up from the inner peripheral edge of the first support surface 17. 18, an annular second support surface 19 formed at the upper end of the first pivot 18, a second pivot 20 erected from the inner periphery of the second support surface 19, and an upper end surface of the second pivot 20. An annular third support surface 21 is formed coaxially with the piston inner 5a. The second pivot 20 is divided into a plurality of blocks along the circumferential direction in order to reduce the weight, and an opening 22 is provided at the center of the second pivot 20 so that the small end 7a of the connecting rod 7 faces. The scattered lubricating oil generated in the crankcase 3, that is, in the crank chamber 3 a passes through the opening 22.

  An annular lock plate 25 placed on the first support surface 17 is rotatably fitted to the first pivot 18 and is fitted to the second pivot 20 so as to face the upper surface of the lock plate 25. The annular first pressing plate 26 to be joined is fixed to the second support surface 19 by a plurality of screws 27, 27. Further, an annular lift member 28 placed on the first pressing plate 26 is rotatably fitted to the second pivot 20, and a second pressing plate 29 facing the upper surface of the inner peripheral edge of the lift member 28. Are fixed to the third support surface 21 by a plurality of screws 34, 34.

  The lift member 28 can reciprocate between a lift position B and a lift release position A set around the second pivot 20, and the piston outer 5 b is moved toward the piston inner 5 a with the reciprocal rotation. It constitutes a main part of a cam mechanism 37 that holds alternately at a position L (see FIGS. 4 and 5) and a high compression ratio position H (see FIGS. 9 and 10) near the combustion chamber 4a.

  That is, as shown in FIGS. 4, 5 and 8, the cam mechanism 37 includes the lift member 28 and a plurality of first cam peaks 38 in an annular arrangement integrally projecting on the upper surface of the lift member 28. 38, and second cam peaks 39, 39, which are annularly arranged to protrude from the lower surface of the head portion of the piston outer 5b, and the top surfaces of the cam peaks 38, 39 are flat. At the same time, both side surfaces arranged in the arrangement direction of the cam peaks 38 and 39 are formed in a rectangular cross-sectional shape that is a vertical surface with respect to the top surface.

  Thus, when the lift member 28 is at the lift release position A, the upper second cam peaks 39, 39... Can enter and leave the valley between the first cam peaks 38, 38. 13), the transition of the piston outer 5b to the low compression ratio position L or the high compression ratio position H is allowed. If the first and second cam peaks 38 and 39 mesh with each other and the top surface of at least one cam peak comes into contact with the valley bottom between the other cam peaks, the cam mechanism 37 is in an axially contracted state, and the piston outer 5b is lowered. A compression ratio position L is given.

  When the lift member 28 is in the lift position B, the first and second cam peaks 38 and 39 abut each other on a flat top surface (see FIG. 14), so that the cam mechanism 37 is in the axially expanded state. Thus, a high compression ratio position H is given to the piston outer 5b. At this time, the extension shaft 15 fixed to the piston pin 6 as described above comes into contact with the lower side surfaces of the long holes 14 and 14 of the ear portions 13 and 13 in the piston outer 5b, so that the piston outer 5b is compressed at a predetermined high compression. Moving beyond the specific position H to the combustion chamber 4a side is prevented.

  As shown in FIGS. 4, 5 and 7, the lock plate 25 reciprocates between an unlock position C (see FIG. 12) and a lock position D (see FIG. 7) set around the first pivot 18. The main part of the lock mechanism 40 that holds the axially contracted state of the cam mechanism 37 at the lock position D is formed.

  That is, the lock mechanism 40 is formed on the lock plate 25, the male spline 41 formed on the outer periphery of the lock plate 25, and the inner periphery of the piston outer 5b so that the male spline 41 is slidably fitted. The female spline 42 and an annular lock groove 43 that allows the upper end of the groove portion of the female spline 42 to communicate with each other and allow the tooth portion of the male spline 41 to rotate and enter, and the low compression of the piston outer 5b. When switching the position between the specific position L and the high compression ratio position H, the lock plate 25 is set to the unlock position C, the male spline 41 is placed in a sliding relationship with the female spline 42, and the piston outer When 5b comes to the low compression ratio position L, the lock plate 25 is rotated to the lock position D so that the tooth portion of the male spline 41 enters the lock groove 43, and the tooth portion of the male spline 41 and the female spline 41 By abutting the end faces to each other with the teeth portion of the in-42, a low compression ratio position L of the piston outer 5b is locked.

  As shown in FIGS. 2 and 10, in order to strengthen the pressing of the lock plate 25 by the first pressing plate 26, it is arranged in a plurality of grooves of the male spline 41 and supports the lower surface of the outer peripheral portion of the first pressing plate 26. Are formed integrally with the piston inner 5a, and the outer periphery of the first pressing plate 26 is fixed to the bosses 35, 35 with a plurality of screws 27 ', 27'. Of course, the bosses 35, 35... Are formed so as not to prevent the male spline 41 from turning to the unlocked position C and the locked position D.

The piston inner 5a is provided with first and second actuators 45 ₁ and 45 _{2 for} driving the lift member 28 and the lock plate 25, respectively, with reference to FIGS. 5, 6, 13 and 14. explain.

First, the first actuator 45 ₁ will be described. The piston inner 5a, a cylinder bore 46 ₁ one side to the same bottom extending parallel of the piston pin 6, a series of long to penetrate the upper wall and the first pressing plate 26 in the middle portion of the cylinder bore 46 ₁ A hole 47 ₁ is provided, and a pressure receiving pin 48 ₁ protruding from the lower surface of the lift member 28 faces the cylinder hole 46 ₁ through the long hole 47 ₁ .

The pressure receiving pin 48 _1, disc-shaped slider 49 ₁ to obtain play in the radial direction in the cylinder bore 46 within ₁ loosely fitted in the cylinder bore 46 ₁ is mounted for relative swinging. An operating plunger 50 ₁ and a bottomed cylindrical return plunger 51 ₁ are slidably fitted in the cylinder hole 46 ₁ with the slider 49 ₁ interposed therebetween. Therefore, the slider 49 ₁ is interposed between the pressure receiving pin 48 ₁ and the operating plunger 50 ₁ and the return plunger 51 ₁ , but the pressure receiving pin 48 ₁ around the center of rotation of the lift member 28. The circular arc movement is permitted by moving the slider 49 ₁ in the cylinder hole 46 ₁ while sliding between the operating plunger 50 ₁ and the return plunger 51 ₁ . Moreover, since the contact between the pressure receiving pin 48 ₁ and the operation plunger 50 ₁ and the return plunger 51 ₁ is always surface contact, the wear resistance of the contact portion is ensured.

A hydraulic chamber 52 ₁ facing the inner end of the operating plunger 50 ₁ is defined in the cylinder hole 46 _{1. When} hydraulic pressure is supplied to the hydraulic chamber 52 ₁ , the operating plunger 50 ₁ receives the hydraulic pressure and the slider 50 ₁ receives the hydraulic pressure. The lift member 28 is rotated to the lift position B via 49 ₁ and the pressure receiving pin 48 ₁ , and the elongated hole 47 ₁ has a size that does not hinder the movement of the pressure receiving pin 48 ₁ at that time. ing.

Also the open end of the cylinder bore 46 _1, the cylindrical spring holding tube 53 ₁ is engaged through the retaining ring 54 _1, between the plunger 51 ₁ returning said this spring holding cylinder 53 _1, its return spring 55 ₁ return for biasing the plunger 51 ₁ on the pressure receiving pin 48 ₁ side is provided in a compressed state.

Thus, the lift release position A of the lift member 28 is defined by the pressure receiving pin 48 ₁ coming into contact with the inner end wall of the elongated hole 47 ₁ on the operating plunger 51 ₁ side (see FIG. 13). lift position B is defined by the pressure receiving pin 48 ₁ comes into contact with the spring holding tube 53 ₁ through a slider 49 ₁ and return the plunger 51 ₁ (see FIG. 14).

Second actuator 45 _2, first actuator 45 ₁ and is axially symmetrical or point-symmetrically disposed across the piston pin 6, the pressure receiving pin 48 ₂ is protruded from the lower surface of the lock plate 25. Since the other configuration is the same as that of the first actuator 45 ₁ , in the drawing, the parts corresponding to the first actuator 45 ₁ are denoted by the same reference numerals with “ ₂ ” as the suffix only, and the details thereof are described. Description is omitted.

Thus, the unlocking position C of the lock plate 25 is defined by the pressure receiving pin 48 ₂ coming into contact with the inner end wall of the long hole 47 _{2 on} the side of the operating plunger 50 ₂ , and the lock position D of the lock plate 25 is is defined by the pressure receiving pin 48 ₂ is brought into contact with the spring holding cylinder 53 ₂ via the slider 49 ₂ and the return plunger 51 _2.

By the way, if the operation strokes of the pressure receiving pins 48 ₁ and 48 ₂ are defined by the inner end walls of the long holes 47 ₁ and 47 ₂ , the operation strokes of the pressure receiving pins 48 ₁ and 48 ₂ can be defined with high accuracy. If the operation strokes of the pressure receiving pins 48 ₁ and 48 ₂ are restricted by bringing the operation plungers 50 ₁ and 50 ₂ and the return plungers 51 ₁ and 51 ₂ into contact with the inner end walls of the cylinder holes 46 ₁ and 46 ₂ , respectively. The load can be removed from the pressure receiving pins 48 ₁ and 48 _{2 at} the operation limit of the pressure receiving pins 48 ₁ and 48 ₂ .

Thus, the first and second actuators 45 ₁ and 45 ₂ are configured to have substantially the same structure, and below the lift member 28 and the lock plate 25 that are stacked one above the other with the first pressing plate 26 in between. It arrange | positions so that the axis line of piston inner 5a may be pinched | interposed. In addition, compatibility is given to parts corresponding to each other of the first and second actuators 45 ₁ and 45 ₂ . As a result, the components of the first and second actuators 45 ₁ and 45 ₂ can be shared, and the cost can be greatly reduced.

As shown in FIGS. 1 and 6, a cylindrical oil chamber 57 is defined between the piston pin 6 and the extension shaft 15 fitted in the hollow portion thereof. First and second distribution oil passages 58 ₁ and 58 ₂ connected to the hydraulic chambers 52 ₁ and 52 ₂ of the second actuators 45 ₁ and 45 ₂ are provided across the piston pin 6 and the piston inner 5a. The oil chamber 57 is connected to an oil passage 59 provided across the piston pin 6, the connecting rod 7 and the crankshaft 9, and this oil passage 59 is connected to an oil pump 61 as a hydraulic pressure source via an electromagnetic main switching valve 60. The oil sump 62 is switchably connected. The oil sump 62 is an oil pan attached to the bottom of the crankcase 3, and therefore the lubricating oil of the engine E is used as the operating oil for the first and second actuators 45 ₁ and 45 ₂ .

  In FIG. 4, the extension shaft 15 has a hollow portion 15b whose open surfaces at both ends are closed by end plates 15a and 15a, and the hollow portion 15b passes through a through hole 16a in the central portion of the extension shaft 15 to form a piston. The hollow portion 15b communicates with the cylindrical oil chamber 57 in the pin 6, and the hollow portion 15b communicates with the long holes 14 and 14 of the ear portions 13 and 13 through the injection holes 16b and 16b at both ends of the extension shaft 15. Is done. At that time, it is desirable that the nozzle holes 16b at each end of the extension shaft 15 are arranged so as to open toward the lower end surface of the corresponding long hole 14, and in the illustrated example, the nozzle holes 16b are arranged at the ends of the extension shaft 15. Even if the piston pin 6 rotates, at least one nozzle hole 16b is directed to the lower end surface of the long hole 14 even if the piston pin 6 rotates.

  As shown in FIGS. 15 and 16, a hydraulic auxiliary switching valve 65 that moves the oil passage 59 in response to the discharge pressure of the oil pump 61 is provided at the large end 7 b of the connecting rod 7. The auxiliary switching valve 65 has a valve chamber 66 formed in the large end portion 7b so as to divide the oil passage 59 into an upstream oil passage 59a on the crankpin 9a side and a downstream oil passage 59b on the piston pin 6 side. And a piston-like valve body 67 slidably accommodated in the valve chamber 66. The valve chamber 66 and the valve body 67 are arranged so that the operating direction of the valve body 67 is parallel to the crankpin 9a. One end of the valve chamber 66 is closed by a screw plug 68, and an end hole 66a is provided in the end wall 66a opposite to the valve chamber 66 to directly open the valve chamber 66 into the crankcase 3. The valve body 67 is configured by integrally connecting hollow cylindrical first and second valve portions 67a and 67b via a partition wall 67c, and the peripheral wall of the first valve portion 67a on the screw plug 68 side is provided with a peripheral wall. A plurality of inlet holes 70 arranged in the direction are provided, and a plurality of outlet holes 71 arranged in the circumferential direction are provided in the peripheral wall of the second valve portion 67b. The valve chamber 66 accommodates a valve spring 72 that urges the valve body 67 toward the screw plug 68 with a predetermined set load. At that time, most of the valve spring 72 is placed in the hollow portion of the second valve portion 67b, and the movable end portion thereof is placed in pressure contact with the partition wall 67c.

  The valve body 67 moves between a retracted position in contact with the screw plug 68 and an advanced position in contact with the end wall 66a. The valve chamber 66 is divided into a switching operation chamber 73 on the screw plug 68 side and an escape chamber 74 on the end wall 66a side by a partition wall 67c of the valve body 67, and the upstream oil passage 59a is formed in the switching operation chamber 73. The downstream oil passage 59b is connected to the escape chamber 74 via the outlet hole 71 when the valve body 67 is in the retracted position, and to the switching operation chamber 73 via the inlet hole 70 when the valve body 67 is advanced. It has come to be.

  In order to avoid interference between the lift member 28, the first pressing plate 26 and the lock plate 25 in the piston outer 5b and the outer sliding flat surfaces 24, 24 on the inner periphery of the piston outer 5b. , Flat chamfering is performed on the outer peripheral surfaces of the lift member 28 and the first pressing plate 26, and a part of the male spline 41 is cut off.

  Next, the operation of the first embodiment will be described.

  As shown in FIGS. 3 to 8 and 13, the lift member 28 of the cam mechanism 37 is in the lift release position A, and the lock plate 25 is engaged with the lock groove 43. Is held at the low compression ratio position L on the piston inner 5a side. Therefore, the compression ratio of the internal combustion engine E operated in this state is controlled to be relatively low.

In order to obtain a high compression ratio state in order to improve the output, for example, at high speed operation of the internal combustion engine E from such a state, the main switching valve 60 is turned on, that is, turned on, and the oil passage 59 is connected to the oil pump 61. Connect to. As a result, the hydraulic oil discharged from the oil pump 61 first flows into the switching operation chamber 73 of the auxiliary switching valve 65 through the upstream oil passage 59a, and the hydraulic pressure of the valve body 67 is changed to the valve valve 67 as shown in FIG. The spring 72 is pushed to the forward position against the set load, and the inlet hole 70 of the valve body 67 is communicated with the downstream oil passage 59b. As a result, the hydraulic oil moves to the downstream oil passage 59b through the inlet hole 70, and the hydraulic pressures of the first and second actuators 45 ₁ and 45 ₂ through the first and second distribution oil passages 58 ₁ and 58 _2. It is supplied to the chambers 52 ₁ and 52 ₂ .

Then, first, as shown in FIG. 9, actuating plunger 50 of the _second actuator 45 ₂ receives the hydraulic pressure in the hydraulic chamber 52 ₂ with slider 49 ₂ pressure receiving pin 48 _2, return biasing force of the spring 55 ₂ since presses against the pressure receiving pin 48 ₂ rotates the lock plate 25 from the locked position D to the unlocked position C, the sliding of the female spline 42 of the male spline 41 and the piston outer 5b of the lock plate 25 The fitting is possible.

  Therefore, the piston outer 5b moves to the high compression ratio position H by the action of the following natural external force. That is, when the piston outer 5b is attracted to the combustion chamber 4a side by the intake negative pressure during the intake stroke of the engine, or by the friction resistance generated between the piston rings 10a to 10c and the inner surface of the cylinder bore 2a during the downward stroke of the piston 5, the piston outer 5b When the piston inner 5a is left behind, or when the piston outer 5b decelerates the piston inner 5a in the latter half of the upward stroke of the piston 5, the piston outer 5b attempts to lift from the piston inner 5a due to its inertial force. The outer 5b is displaced in a direction away from the piston inner 5a toward the combustion chamber 4a, and the extension shaft 15 supported by the piston inner 5a is moved relative to the long holes 14 and 14 of the ear portions 13 and 13 of the piston outer 5b. By lowering and abutting against the lower end walls of the long holes 14, 14, the piston arm Motor 5b is the displacement is prevented by the predetermined high compression ratio position H.

Therefore, the movement limit of the piston outer 5b toward the high compression ratio position can be restricted without using a special stopper member, which can contribute to simplification of the structure of the device. In addition, the impact at the time of restricting the movement limit of the piston outer 5b to the high compression ratio position side is directly transmitted from the piston outer 5b to the piston pin 6 through the long holes 14 and 14 and the extension shaft 15 that are in contact with each other. Since it is not transmitted to the piston inner 5a, it is possible to prevent the influence of the impact on the cam mechanism 37, the lock mechanism 40, the first and second actuators 45 ₁ , 45 _{2 and the} like provided on the piston inner 5a. Durability and operational stability can be ensured.

When the piston outer 5b comes to the high compression ratio position H, the first cam peaks 38, 38... Of the lift member 28 disengage from the valleys between the second cam peaks 39, 39. in 45 _1, already pushed against the urging force of the hydraulic chamber 52 actuating plunger 50 ₁ had received the oil pressure of ₁ returns the pressure receiving pin 48 ₁ with the slider 49 _first spring 55 _1, the lift member 28 It rotates from the lift release position A to the lift position B. Therefore, as shown in FIG. 14, the first cam peaks 38, 38... And the second cam peaks 39, 39. That is, the cam mechanism 37 is in the axially expanded state.

  Thus, the piston outer 5b is held at the high compression ratio position H by the axially expanded state of the cam mechanism 37 and the contact between the extension shaft 15 and the long holes 14, 14 at the lower end walls. Therefore, the piston inner and the outer 5a, 5b can move up and down in the cylinder bore 2a together while increasing the compression ratio, thereby contributing to the improvement of the output performance of the engine. In addition, in the cam mechanism 37, the contact surfaces of the top surfaces of the first and second cam peaks 38, 39 that are annularly contacted with each other are evenly distributed over the entire circumference of the piston 5, and the total area thereof is wide. Therefore, the cam mechanism 37 can sufficiently withstand a large in-cylinder pressure in the expansion stroke and compression stroke of the engine E.

By the way, when the main switching valve 60 is turned on and the oil passage 59 is connected to the oil pump 61, the hydraulic oil that has traveled up the oil passage 59 is transferred to the first and second actuators 45 ₁ and 45 ₂ . In addition to the supply, the oil chamber 57 in the piston pin 6, the through hole 16 a and the hollow portion 15 b of the extension shaft 15 are sequentially passed through the nozzle holes 16 b and 16 b to the inside of the long holes 14 and 14 of the ear portions 13 and 13 of the piston inner 5 a. Since the inside of the long holes 14 and 14 is filled with hydraulic oil, the extension shaft 15 becomes an ear portion as the piston outer 5b moves from the low compression ratio position L to the high compression ratio position H. The lower half circumferential surface of the extension shaft 15 presses the working oil in the long holes 14 and 14 by lowering the long holes 14 and 14 of the thirteen and thirteen, and the working oil passes through the gaps around the ear portions 13 and 13. Extruded out of the long holes 14, 14 Due to the damping force, the abutment impact of the extension shaft 15 on the bottom holes 14 and 14 of the lower end wall is mitigated, and the piston outer 5b can be reliably restricted to the high compression ratio position H. The durability of 15 can be improved.

  In addition, it is desirable that the nozzle hole 16b provided in the extension shaft 15 be one that faces the lower end wall of the corresponding long hole 14. In this way, when the outer inner 5b comes to the high compression ratio position H, the single injection hole 16b is closed by the lower end wall of the corresponding long hole 14, and unnecessary outflow of hydraulic oil from the injection hole 16b is suppressed. This is because the capacity of the oil pump 61 can be reduced.

  Further, in the intake stroke, the load in the separation direction acting on the piston outer 5b and the piston inner 5a has an extension shaft 15 supported by the piston inner 5a and elongated holes 14 and 14 into which the extension shaft 15 is fitted. The ears 13 and 13 of the piston outer 5b can be reliably supported, and the extension shaft 15 and the long holes 14 and 14 serve to prevent relative rotation of the piston inner 5a and the piston outer 5b. Contributes to simplification of structure. Moreover, since the piston outer 5b is strong enough to make the ears 13 and 13 forming the long holes 14 and 14 thick, it can contribute to the weight reduction of the piston outer 5b.

  Next, to switch the engine E from the high compression ratio state to the low compression ratio state again, the main switching valve 60 is turned off as shown in FIG. The reservoir 62 is opened. Then, as the upstream oil passage 59a is depressurized, the switching operation chamber 73 of the auxiliary switching valve 65 is also depressurized. It communicates with the downstream oil passage 59b. As a result, the downstream oil passage 59b is directly released to the crank chamber 3a (see FIG. 1) through the outlet hole 71, the escape chamber 74, and the escape hole 69 of the auxiliary switching valve 65.

Thereafter, before and after the piston 5 passes through the bottom dead center, the hydraulic oil in the downstream oil passage 59b in the connecting rod 7 has a downward inertial force. Discharge immediately to 3a. As a result, the hydraulic chambers 52 ₁ and 52 ₂ of the first and second actuators 45 ₁ and 45 ₂ connected to the downstream oil passage 59b are immediately decompressed, and the pressure receiving pins 48 of the first and second actuators 45 ₁ and 45 ₂ are used. ₁ and 48 ₂ are placed under the control of return plungers 51 ₁ and 51 ₂ receiving the urging forces of the return springs 55 ₁ and 55 ₂ , respectively.

The main selector valve 60 in the off state, while the process until the hydraulic chamber 52 of the _first and second actuators 45 _1, 45 _2, 52 ₂ depressurized with reference to the diagram of FIG. 17 and FIG. 18 described To do.

In FIGS. 17 and 18, the line X is the in-cylinder pressure of the engine E, the line Y is the pressure in the hydraulic chambers 52 ₁ and 52 ₂ of the first and second actuators 45 ₁ and 45 ₂ , and the line Z is the auxiliary switching valve 65. shows the discharge pressure of the oil pump 61 according to the switching operation chamber 73, respectively, also the line S is the threshold value of the pressure applied to the hydraulic pressure chamber 52 _1, 52 _2, first and second actuator if the pressure is above the threshold value S 45 ₁ and 45 ₂ are in an activated state, and when the value is less than the threshold value S, the first and second actuators 45 ₁ and 45 ₂ are inactivated.

The pressure of the hydraulic chambers 52 _1, 52 ₂ are pulsations in the on state of the main selector valve 60, the inertia of the working oil of the piston 5 and the hydraulic chamber 52 ₁ In conjunction with the reciprocating motion of the connecting rod 7, 52 ₂ and the oil passage 59 By changing the direction of force.

When the main switching valve 60 is turned off at time T and the auxiliary switching valve 65 is moved backward, before and after the bottom dead center between the explosion stroke and the exhaust stroke of the engine E and before and after the bottom dead center between the suction stroke and the compression stroke. , There is a time when the hydraulic oil in the downstream oil passage 59b has a downward inertial force, so at any time, the hydraulic oil in the downstream oil passage 59b enters the crank chamber 3a from the relief hole 69 of the auxiliary switching valve 65. By discharging, the pressure in the hydraulic chambers 52 ₁ and 52 ₂ can be quickly reduced below the threshold value.

If there is no such auxiliary switching valve 65, the first and second actuators 45 ₁ and 45 ₂ are forced to set a large set load of the return springs 55 ₁ and 55 _2. Along with this, it is necessary to increase the hydraulic pressure of the operating plungers 51 ₁ and 51 ₂ , that is, the discharge pressure of the oil pump 61, which increases the pressure of the oil pump 61 and consequently increases the power consumption for driving the oil pump 61. .

Thus, when the hydraulic pressure chamber 52 _1, 52 ₂ decreases below a threshold, first, the first actuator 45 _1, returns the plunger 51 ₁ is pushed by the oil pressure chamber 52 ₁ side pressure receiving pin 48 ₁ with the slider 49 ₁ Then, the lift member 28 is rotated to the lift release position A, and the first cam peaks 38, 38... And the second cam peaks 39, 39. In the expansion stroke and compression stroke, the piston outer 5b is pressed against the piston inner 5a by the in-cylinder pressure, or the friction resistance generated between the piston rings 10a to 10c and the inner surface of the cylinder bore 2a in the upward stroke of the piston 5 When the outer 5b is pressed against the piston inner 5a or when the piston inner 5a is decelerated in the latter half of the downward stroke of the piston 5, the piston outer 5b When the piston outer 5b is pressed against the piston inner 5a by the inertial force of FIG. 13, the piston outer 5b engages the first cam peaks 38, 38... And the second cam peaks 39, 39. The low compression ratio position L of the piston outer 5b is determined by the displacement so as to be close to the piston inner 5a and the top of one cam peak 39 abutting against the valley bottom between the other cam peaks 38.

When the piston outer 5b reaches the low compression ratio position L, the male splines 41 of the lock plate 25, since it is possible enter the locking groove 43 of the piston outer 5b, the spring plunger 51 ₂ return of the second actuator 45 ₂ returns 55 the pressure receiving pin 48 ₂ with slider 49 _{2 2} with a force and pushes the hydraulic chamber 52 ₂ side, rotates the lock plate 25 to the locking position D, and the locking mechanism 40 in a locked state. That is, the male spline 41 of the lock plate 25 is made to face the upper end surface of the female spline 42 of the piston outer 5b, thereby preventing the two splines 41 and 42 from sliding relative to each other.

  By the way, the first pressing plate 26 that prevents the lock plate 25 from lifting from the first support surface 17 of the piston inner 5a is supported by the second support surface 19 of the piston inner 5a. Even if a thrust load is applied to the holding plate 26, the load is received by the second support surface 19 and is prevented from being transmitted to the lock plate 25, so that the lock plate 25 always rotates smoothly around the first pivot 18. can do.

  Thus, the piston outer 5 b is held at the low compression ratio position L by the axially contracted state of the cam mechanism 37 and the locked state of the lock mechanism 40. Even in this state, in the cam mechanism 37, the top of one cam peak 39 of the first and second cam peaks 38, 39 in the annular arrangement hits the valley bottom between the other cam peaks 38. Are uniformly distributed over the entire circumference of the piston 5 and have a large total area, the cam mechanism 37 can sufficiently withstand a large in-cylinder pressure during the expansion stroke and compression stroke of the engine E.

  Further, the load in the separating direction acting on the piston outer 5b and the piston inner 5a during the intake stroke or the like acts on the end surface contact portion between the male spline 41 of the lock plate 25 and the female spline 42 of the piston outer 5b. Since the abutting portions are evenly distributed over the entire circumference of the piston 5 and the total area thereof is wide, the lock mechanism 40 can sufficiently withstand the load in the separation direction.

  As described above, the cam mechanism 37 is annularly disposed between the piston inner and the outer 5a, 5b, so that the piston inner and the outer 5a, 5b are placed around the entire circumference of the cam inner 37 via the cam mechanism 37. Therefore, the heat transfer between the piston inner and the outer 5a, 5b, in particular, the heat drawing from the high temperature piston outer 5b to the low temperature piston inner 5a is smooth, and the piston 5 is good. Coolability can be ensured. At the same time, the transmission of thrust between the piston inner and the outer 5a, 5b is efficient, which can contribute to improving the durability of the piston 5.

  Moreover, the piston inner 5a is integrally formed with skirt portions 12, 12 that are guided to slide on the inner peripheral surface of the cylinder bore 2a of the engine E, and the peripheral wall on which the piston rings 10a to 10c of the piston outer 5b are mounted. Since the piston outer 5b does not have a skirt portion because it ends immediately above the skirt portions 12, 12, the piston outer 5b is positioned between the low compression ratio position L and the high compression ratio position H by utilizing its inertial force. Even when switching, the piston outer 5b can smoothly switch the position without being obstructed by the frictional resistance between the skirt portions 12, 12 and the inner peripheral surface of the cylinder bore 2a.

  Further, since the skirt portions 12 and 12 are formed on the piston inner 5a, the double overlapping portion of the piston inner and the outer 5a and 5b is greatly reduced, the piston is significantly reduced in weight, and the output performance of the engine E is achieved. And it can contribute to improvement of durability.

  Furthermore, without interfering with the skirt portions 12 and 12 of the piston inner 5 a, the long holes 14 and 14 of the ear portions 13 and 13 of the piston outer 5 b disposed to face the piston pin 6 protrude from both ends of the piston pin 6. The relative rotation of the piston inner and the outer 5a, 5b can be reliably prevented by an extremely simple structure in which the extension shaft 15 is slidably fitted.

Further, an opening 22 is provided at the center of the second pivot 20 of the piston inner 5a so that the small end 7a of the connecting rod 7 faces, and the scattered lubricating oil generated in the crankcase 3, that is, in the crank chamber 3a, is provided in the opening. Therefore, during the operation of the engine E, scattered lubricating oil is supplied to the cam mechanism 37 through the opening 22 to lubricate and cool the mechanism 37, and the reliability and durability of the operation is ensured. It can contribute to the improvement of sex. In addition, since the lubricating oil of the engine E is used as the hydraulic oil for the first and second actuators 45 ₁ and 45 ₂ , the cam mechanism 37 is lubricated by the hydraulic oil leaking from the actuators 45 ₁ and 45 _2. It can be performed more effectively.

  On the other hand, the valve element 67 of the auxiliary switching valve 65 provided at the large end portion 7b of the connecting rod 7 rotates with the large end portion 7b, and therefore receives a simple centrifugal force. Among these, since the impact received by the valve body 67 is small, its durability can be easily ensured. In addition, during the rotation of the large end portion 7b, the valve element 67 receives a centrifugal force in a direction orthogonal to the operation direction thereof, so that a malfunction due to the centrifugal force can be avoided. This makes it possible to set the valve spring 72 with a low set load, and is effective in enhancing the hydraulic response of the valve body 67.

  The set load of the valve spring 72 that urges the valve body 67 in the backward direction is set to a size that can hold the valve body 67 in the backward position even by the pressure increase due to the centrifugal force of the residual oil in the switching operation chamber 73. Needless to say, there is a need.

By the way, as described above, the lock plate 25 and the lift member 28 are configured to be rotatably supported on the first and second pivots 18 and 20 integral with the piston inner 5a, respectively, and operate the first. Since the second actuators 45 ₁ and 45 ₂ are arranged so as to sandwich the axis of the piston inner 5a, the weight of the piston 5 can be reduced and the size thereof can be reduced. In particular, the lift member 28 and the lock plate 25 and the first and second actuators 45 ₁ and 45 ₂ are arranged below the lift member 28 and the lock plate 25 that are arranged one above the other. The actuators 45 ₁ and 45 ₂ can be rationally concentrated, and the weight and size of the piston 5 can be further reduced.

  In addition, since both the rotary lift member 28 and the lock plate 25 are given vibration due to the reciprocating motion of the piston and are supplied with lubricating oil, they are reliably secured by the single first and second actuators. Can be rotated.

  Next, another embodiment of the present invention shown in FIGS. 19 and 20 will be described.

  In this other embodiment, the closed portion 42a integrated with the piston inner 5a that restricts the movement limit of the piston outer 5b toward the high compression ratio position H by receiving the teeth of the male spline 41 in the groove of the female spline 42. Is provided. In this case, at the high compression ratio position H of the piston outer 5b, the long holes 14, 14 of the ear portions 13, 13 in the piston outer 5b are provided in order to ensure the contact of the teeth of the male spline 41 with the closing portion 42a. The extension shaft 15 that moves up and down together with the piston pin 6 does not contact the lower end wall. Since other configurations are the same as those of the previous embodiment, portions corresponding to those of the previous embodiment in FIG. 16 and FIG. 17 are denoted by the same reference numerals, and redundant description is omitted.

  Thus, according to this other embodiment, the limit of movement of the piston outer 5b to the high compression ratio position H side is surely regulated by a very simple structure in which the closed portion 42a is provided in the groove portion of the female spline 42. be able to.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the scope of the invention. For example, the auxiliary switching valve 65 may be configured as an electromagnetic type that is turned on / off simultaneously with the electromagnetic main switching valve 60. In order to regulate the low compression ratio position L of the piston outer 5b, the lower end surface of the piston outer 5b can be brought into contact with the upper end surfaces 12a, 12a of the skirt portions 12, 12 of the piston inner 5a. Further, the variable compression ratio device of the above embodiment is low when the first and second actuators 45 ₁ , 45 ₂ are inoperative, that is, when the operating plungers 50 ₁ , 50 ₂ are retracted by the biasing force of the return springs 55 ₁ , 55 ₂ . Although the compression ratio state is obtained so that the low compression ratio is emphasized, the high compression ratio is emphasized when the first and second actuators 45 ₁ and 45 ₂ are not operated. It can also be configured.

  In the above embodiment, the shock absorber for reducing the contact impact of the extension shaft 15 against the lower end wall of the long hole 14 is hydraulic. However, the extension shaft 15 is made of an elastic member embedded in the lower end wall of the long hole 14. It can be configured as a mechanical type that can be elastically received, or the above-described hydraulic type can be used in combination.

1 is a longitudinal sectional front view of a main part of an internal combustion engine provided with a variable compression ratio device according to an embodiment of the present invention. It is a disassembled perspective view from the upper part of the said compression ratio variable apparatus. It is a disassembled perspective view from the downward direction of the compression ratio variable apparatus. It is a principal part enlarged view (low compression ratio state) of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 5. FIG. 5 is a correspondence diagram with FIG. 4 showing a high compression ratio state. FIG. 10 is a sectional view taken along line 10-10 in FIG. 9; It is the 11-11 line sectional view of FIG. 12 is a sectional view taken along line 12-12 of FIG. FIG. 13 is a cross-sectional view taken along line 13-13 in FIG. 5 (low compression ratio state). FIG. 14 is a diagram corresponding to FIG. 13 showing a high compression ratio state. It is an enlarged view (low compression ratio state) of the auxiliary switching valve part in FIG. FIG. 16 is a correspondence diagram with FIG. 15 showing a high compression ratio state. It is a diagram which shows the hydraulic pressure change of the hydraulic actuator accompanying the action | operation of an auxiliary switching valve. FIG. 18 is an enlarged view of a portion 18 in FIG. 17. FIG. 13 is a view corresponding to FIG. 12 showing another embodiment of the present invention. FIG. 20 is a sectional view taken along line 20-20 in FIG. 19.

Explanation of symbols

A ... Lift release position B ... Lift position C ... Lock release position D ... Lock position H ... High compression ratio position L ... Low compression ratio position 5 ... Piston 5a ... Piston inner 5b ... Piston outer 6 ...・ Piston pin 7 ・ ・ ・ ・ ・ ・ Connecting rod 14 ・ ・ ・ ・ ・ ・ ・ ・ Long hole 15 ・ ・ ・ ・ ・ ・ ・ ・ Shaft (extension shaft)
25... Lock plate 28... Lift member 37... Cam mechanism 38. ...... lock mechanism 41 ...... male spline 42 ...... female splines 42a ..... closed portion 43 ...... locking groove 45 ₁ ..... 1st actuator 45 ₂ ... 2nd actuator

Claims (4)

A piston inner (5a) connected to the connecting rod (7) via a piston pin (6); and an outer periphery of the piston inner (5a) is slidably fitted only in the axial direction, and the outer end surface is connected to a combustion chamber ( A piston outer (5b) capable of moving between the low compression ratio position (L) near the piston inner (5a) and the high compression ratio position (H) near the combustion chamber (4a) while facing 4a); The lift release position (A), which is interposed between the piston inner and the outer (5a, 5b) and allows the piston outer (5b) to move to the low compression ratio position (L), and the piston outer (5b) are highly compressed. A lift member (28) capable of moving between the lift positions (B) held at the specific position (H); and a first member that operates the lift member (28) to the lift release position (A) and the lift position (B). actuator (45 ₁ And disposed between the piston inner (5a) and the piston outer (5b), and when the piston outer (5b) comes to the low compression ratio position (L), the piston inner (5a) and the piston outer (5b) A locking mechanism (40) for preventing relative movement in the axial direction;
The lock mechanism (40) is a lock groove that allows the axial female spline (42) formed on the inner peripheral surface of the piston outer (5b) to communicate with the upper end of the groove of the female spline (42). (43) and a male spline (41) corresponding to the female spline (42) on the outer periphery, and when the piston outer (5b) is at the high compression ratio position (H), the male spline (41) Occupies an unlocked position (C) that can slide with respect to the female spline (42), and when the piston outer (5b) is in the low compression ratio position (L), the male spline (41) A lock plate (25) attached to the piston inner (5a) so as to occupy a lock position (D) that enters and rotates into the lock groove (43) and is prevented from sliding with respect to the female spline (42). Constituted by a, in its locking plate (25), characterized in that it was connected to a second actuator (45 ₂₎ which operates in the unlocking position (C) and locking position (D), the internal combustion engine Variable compression ratio device. In the internal combustion engine variable compression ratio device according to claim 1,
By fitting a shaft portion (15) connected to both ends of the piston pin (6) into a long hole (14) formed in the piston outer (5b) and having a long diameter in the axial direction thereof, A variable compression ratio device for an internal combustion engine, wherein relative rotation of the piston inner (5a) and the piston outer (5b) is prevented. In the internal combustion engine variable compression ratio device according to claim 2,
The movement limit of the piston outer (5b) to the high compression ratio position (H) side is regulated by bringing the shaft (15) into contact with the lower end wall of the long hole (14). An internal combustion engine variable compression ratio device. In the internal combustion engine variable compression ratio device according to claim 2,
In the groove portion of the female spline (42), a blocking portion (42a) that receives the tooth portion of the male spline (41) and restricts the movement limit of the piston outer (5b) to the high compression ratio position (H) side. A variable compression ratio device for an internal combustion engine, comprising:

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