JP2008106676A - Variable stroke characteristics engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a decrease in rigidity of a cylinder due to the notch when a notch for preventing interference is formed in a lower end portion of a cylinder of a variable stroke characteristic engine.
SOLUTION: Since a first notch 5a through which the upper link 61 passes and the lower link 60 does not pass is formed at the lower end portion of the cylinder 5 on the first connecting portion side that connects the upper link 61 and the lower link 60, A reduction in rigidity of the cylinder 5 can be minimized as compared with the case where the first notch 5a through which the entire first connecting portion passes is formed. In addition, since a single second notch 5b through which the lower link 60 passes is formed at the lower end of the cylinder 5 on the second connecting part side that connects the lower link 60 and the control link 63, a plurality of second notches 5b. Compared with the case of forming, the number of the second cutouts 5b can be reduced to minimize the decrease in the rigidity of the cylinder 5.
[Selection] FIG.

Description

  The present invention relates to a piston that is slidably fitted to a cylinder, a crankshaft, and a variable stroke link mechanism that connects a control shaft, a lower link that is swingably supported by the crankshaft, and a lower link that is a piston. This invention relates to a variable stroke characteristic engine comprising an upper link connected to a control link and a control link connecting a lower link to a control shaft.

  An upper link having one end connected to the piston pin of the piston, a lower link connected to the other end of the upper link and connected to the crank pin of the crankshaft, and one end connected to the lower link, A variable stroke characteristic engine that includes a variable stroke link mechanism including a control link that is swingably connected to an engine body, and that can move a piston movement stroke by driving the control link with an actuator. 1 is known.

  In such a variable stroke characteristic engine, the moving range of the variable stroke link mechanism including the upper link, the lower link, and the control link is wider than the moving range of a simple connecting rod. In order to avoid the interference, there is a problem that the size of the engine in the cylinder axial direction increases.

Therefore, the one described in the above cited document 1 is such that the connecting portion of the upper link and the lower link passes through one side of the lower end portion of the cylinder in order to prevent the variable stroke link mechanism from interfering with the lower end portion of the cylinder. A single cutout is formed, and a plurality of cutouts through which the lower link passes are formed on the other side of the lower end portion of the cylinder.
JP 2006-183595 A

  However, if a notch is formed in the lower end portion of the cylinder in order to avoid interference with the variable stroke link mechanism, there is a problem that the rigidity of the cylinder decreases due to the notch.

  The present invention has been made in view of such circumstances, and when a notch for preventing interference is formed at the lower end portion of a cylinder of a variable stroke characteristic engine, a reduction in cylinder rigidity due to the notch is minimized. With the goal.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a variable stroke link mechanism for connecting a piston, a crankshaft, and a control shaft that are slidably fitted to a cylinder, and a crankshaft. The upper link and the lower link are connected in a variable stroke characteristic engine consisting of a lower link supported in a swingable manner, an upper link that connects the lower link to the piston, and a control link that connects the lower link to the control shaft. A variable stroke characteristic engine is proposed in which a notch through which the upper link passes and the lower link does not pass is formed at the lower end of the cylinder on the connecting portion side.

  According to the second aspect of the present invention, the stroke variable link mechanism that connects the piston, the crankshaft, and the control shaft that are slidably fitted to the cylinder is supported by the crankshaft so as to be swingable. In a variable stroke characteristic engine composed of a lower link, an upper link that connects the lower link to the piston, and a control link that connects the lower link to the control shaft, the cylinder on the connecting side that connects the lower link and the control link A variable stroke characteristic engine is proposed, characterized in that a single notch through which the lower link passes is formed at the lower end.

  According to a third aspect of the present invention, in addition to the configuration of the first aspect, there are receiving surfaces for receiving the skirt portion of the piston on both sides in the circumferential direction of the notch, and the circle of the notch. A variable stroke characteristic engine is proposed, characterized in that the circumferential width is smaller than the width between the outer end faces of the lower link.

  According to the invention described in claim 4, in addition to the structure of claim 2, there are receiving surfaces for receiving the skirt portion of the piston on both sides in the circumferential direction of the notch, and the circle of the notch. A variable stroke characteristic engine is proposed in which the width in the circumferential direction is smaller than the width between the outer end surfaces of a pair of counterweights provided on the crankshaft.

  According to the fifth aspect of the present invention, the stroke variable link mechanism that connects the piston slidably fitted to the cylinder, the crankshaft, and the control shaft is supported by the crankshaft so as to be swingable. In the variable stroke characteristic engine composed of the lower link, the upper link that connects the lower link to the piston, and the control link that connects the lower link to the control shaft, the first connecting portion side that connects the upper link and the lower link A first notch through which the upper link passes and the lower link does not pass is formed at the lower end portion of the cylinder, and the lower link passes through the lower end portion of the cylinder on the second connecting portion side that connects the lower link and the control link. A single second cutout is formed on both sides in the circumferential direction of the first and second cutouts. There is a receiving surface for receiving the skirt portion of the piston, the circumferential width of the first notch is narrower than the circumferential width of the second notch, and the cylinder axis direction of the first notch A variable stroke characteristic engine is proposed, characterized in that the height is higher than the height of the second notch in the cylinder axis direction.

  According to the first aspect of the present invention, since the notch through which the upper link passes and the lower link does not pass is formed at the lower end portion of the cylinder on the connecting portion connecting the upper link and the lower link, the entire connecting portion Compared with the case of forming a notch through which the cylinder passes, the notch can be made smaller to minimize the decrease in the rigidity of the cylinder.

  According to the second aspect of the present invention, since the single notch through which the lower link passes is formed at the lower end of the connecting portion side cylinder that connects the lower link and the control link, a plurality of lower links pass through. Compared with the case where notches are formed, the number of notches can be reduced to minimize a decrease in cylinder rigidity.

  According to the third aspect of the present invention, there is a receiving surface for receiving the skirt portion of the piston on both sides in the circumferential direction of the notch at the lower end portion of the cylinder, and the circumferential width of the notch is lower than that of the lower link. Since it is smaller than the width between the outer end faces, it is possible to suppress the enlargement of the notch and to prevent the piston from becoming unstable due to the formation of the notch.

  According to the fourth aspect of the present invention, there is a receiving surface for receiving the skirt portion of the piston on both sides in the circumferential direction of the notch at the lower end portion of the cylinder, and the circumferential width of the notch is in the crankshaft. Since the width is smaller than the width between the outer end surfaces of the pair of counterweights provided, it is possible to suppress an increase in size of the notch and to prevent the piston from becoming unstable due to the formation of the notch.

  Further, according to the configuration of the fifth aspect, since the first notch through which the upper link passes and the lower link does not pass is formed at the lower end portion of the cylinder on the first connecting portion side that connects the upper link and the lower link. Compared with the case where the first notch through which the entire first connecting portion passes is formed, the first notch can be made smaller to minimize the decrease in the rigidity of the cylinder. In addition, since a single second notch through which the lower link passes is formed at the lower end of the cylinder on the second connecting portion side that connects the lower link and the control link, a plurality of second notches through which the lower link passes are formed. Compared with the case of forming, the number of second notches can be reduced to minimize the decrease in cylinder rigidity. Also, since there are receiving surfaces for receiving the skirt of the piston on both sides in the circumferential direction of the first and second cutouts at the lower end of the cylinder, the piston behavior is not improved by forming the first and second cutouts. It can prevent becoming stable. The circumferential width of the first notch is narrower than the circumferential width of the second notch, and the height of the first notch in the cylinder axial direction is greater than the height of the second notch in the cylinder axial direction. Therefore, the difference in area between the first and second notches can be reduced to prevent the piston behavior from becoming unstable.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 13 show a first embodiment of the present invention. FIG. 1 is a schematic overall perspective view of a variable stroke characteristic engine, FIG. 2 is a view in the direction of the arrow 2 in FIG. 1, and FIG. 4 is a sectional view taken along line 3-3 (high compression ratio state), FIG. 4 is a sectional view taken along line 4-4 in FIG. 1 (low compression ratio state), FIG. 5 is a sectional view taken along line 5-5 in FIG. 5 is a cross-sectional view taken along line 6-6, FIG. 7 is an enlarged vertical view taken along line 7-7 in FIG. 5, FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 3, and FIG. 10 is an exploded perspective view of the actuator, FIG. 11 is a hydraulic circuit diagram of the control system of the actuator, FIG. 12 is an enlarged sectional view of the main part of the engine, and FIG. 13 is an enlarged sectional view taken along line 13-13 of FIG.

  As shown in FIGS. 1 to 4, the variable stroke characteristic engine E according to the present invention is for an automobile and is placed horizontally in an engine room of an automobile (not shown) (the crankshaft 30 is in the traveling direction of the automobile). Mounted horizontally). When this engine E is mounted on an automobile, as shown in FIG. 2, the cylinder is slightly tilted backward, that is, its cylinder axis LL is slightly tilted backward with respect to the vertical line.

  The variable stroke characteristic engine E is an in-line four-cylinder OHC type four-cycle engine. The engine body 1 includes a cylinder block 2 in which four cylinders 5 are provided in parallel in the lateral direction, and the cylinder block. The cylinder head 3 is integrally coupled to the two deck surfaces via the gasket 6, the upper block 40 (upper crankcase) is integrally formed at the lower portion of the cylinder block 2, and is integrally coupled to the lower surface thereof. The lower block 41 (lower crankcase) is provided, and the crankcase 4 is formed by the upper block 40 and the lower block 41. A head cover 9 is integrally crowned on the upper surface of the cylinder head 3 via a sealing material 8, and an oil pan 10 is integrally coupled to the lower surface of the lower block 41 (lower crankcase).

  Pistons 11 are slidably fitted to the four cylinders 5 of the cylinder block 2, and four combustion chambers 12 are provided on the lower surface of the cylinder head 3 facing the top surfaces of the pistons 11. An intake port 14 and an exhaust port 15 communicating with those combustion chambers 12 are formed. An intake valve 16 is provided in the intake port 14 and an exhaust valve 17 is provided in the exhaust port 15 so as to be opened and closed. On the cylinder head 3, a valve operating mechanism 18 for opening and closing the intake valve 16 and the exhaust valve 17 is provided. The valve mechanism 18 swings on an intake side cam shaft 20 and an exhaust side cam shaft 21 that are rotatably supported by the cylinder head 3, and on an intake side and exhaust side rocker shafts 22, 23 provided on the cylinder head 3. The intake side and exhaust side camshafts 20 and 21 and the intake side and exhaust side rocker arms 24 and 25 connected to the intake valve 16 and the exhaust valve 17 so as to be pivotally supported are provided. According to the rotation of the shafts 20 and 21, the intake side and exhaust side rocker arms 24 and 25 are swung against the valve closing force of the valve springs 26 and 27, and the intake valve 16 and the exhaust valve 17 are moved at a predetermined timing. Can open and close.

  As shown in FIG. 2, the intake-side and exhaust-side camshafts 20, 21 are interlocked with a crankshaft 30 described later via a conventionally known timing transmission mechanism 28, and according to the rotation of the crankshaft 30, It is driven at half the rotational speed. The valve mechanism 28 is covered with a head cover 9 that is integrally crowned on the cylinder head 3. The cylinder head 3 is provided with a cylindrical plug insertion cylinder 31 corresponding to the four cylinders, and a spark plug 32 is inserted into the plug insertion cylinder 31.

  A plurality of intake ports 14 corresponding to the four cylinders 5 are opened toward the front surface of the engine body 1, that is, toward the front side of the vehicle, and an intake manifold 34 of the intake system IN is connected thereto. Since the intake system IN has a conventionally known structure, a detailed description thereof will be omitted.

  A plurality of exhaust ports 15 corresponding to the four cylinders 5 are opened toward the rear surface of the engine body 1, that is, toward the rear side of the vehicle, and an exhaust manifold 35 of the exhaust system EX is connected thereto. Since the exhaust system EX has a conventionally known structure, a detailed description thereof is omitted.

  As shown in FIGS. 3 and 4, the crankcase 4 including the upper block 40 (upper crankcase) at the lower part of the cylinder block 2 and the lower block 41 (lower crankcase) is more than the portion of the cylinder 5 of the cylinder block 2. Stretching forward (in front of the vehicle), in the crank chamber CC of the overhanging portion 36, a stroke variable link mechanism LV (described later) that makes the moving stroke of the piston 11 variable, and a hydraulic actuator AC that drives the link mechanism LV. (Described later) is provided.

  As shown in FIGS. 2, 3, 5, and 6, a lower block 41 is fixed to the lower surface of the upper block 40 integrally formed with the lower portion of the cylinder block 2 with a plurality of connecting bolts 42. The center bearing member 54 is fixed with a bearing cap tightening bolt 57.

  The journal shaft 30J of the crankshaft 30 is rotatably supported by a plurality of journal bearing portions 43 formed on the mating surfaces of the upper block 40 and the lower block 41 (see FIG. 8).

  As shown in FIG. 5, the lower block 41 is cast and molded in a closed cross-sectional structure having a square shape in plan view, and end bearing members 50 and 51 are provided at the left and right ends thereof, and a left portion thereof is provided at the intermediate portion thereof. The right intermediate bearing members 52 and 53 are further provided with a central bearing member 54 (a housing HU described later is integrally formed) as a bearing cap at the center thereof. The journal shaft 30J of the shaft 30 is supported.

  As shown in FIGS. 5, 6, and 9, the central bearing member, that is, the bearing cap 54 is formed separately from the lower block 41, and a plurality of bearing cap tightening bolts 56 are attached to the lower block 41. The bearing cap 54 is also firmly fixed to the lower surface of the upper block 40 by other bearing cap tightening bolts 57. One side portion of the central bearing member, that is, the bearing portion 54A of the crankshaft 30 of the bearing cap 54 that is biased toward one side (the front of the engine body 1) is an enormous portion 58 that has an enlarged vertical width and is thick. This enormous portion 58 is provided with a housing HU for a hydraulic actuator AC, which will be described in detail later.

  Here, the housing HU may be cast and formed in the enormous portion 58 of the bearing cap 54.

  Next, returning to FIGS. 3 and 4, the structure of the variable stroke link mechanism LV that makes the moving stroke of the piston 11 variable will be described. The structure is rotatably supported on the mating surface of the upper block 40 and the lower block 41. An intermediate portion of a triangular lower link 60 is pivotally connected to the plurality of crank pins 30P of the crankshaft 30 so as to be swingable. One end (upper end) of the lower link 60 is pivotally connected to the lower end (large end) of an upper link (connecting rod) 61 pivotally connected to the piston pin 13 of the piston 11 via a first connecting pin 62. The upper end of the control link 63 is pivotally connected to the other end (lower end) of each lower link 60 via the second connecting pin 64. The control link 63 extends downward, and an eccentric pin 65P of a control shaft 65 (detailed later) is pivotally connected to the lower end of the control link 63. The control shaft 65 is driven within a predetermined angle range (about 90 degrees) by a hydraulic actuator AC (described in detail later), and the control link 63 is driven to swing by the displacement of the eccentric pin 65P. Specifically, the control shaft 65 rotates between a first position shown in FIG. 3 (the eccentric pin 65P is a lower position) and a second position shown in FIG. 4 (the eccentric pin 65P is a left position). Is possible. In the first position shown in FIG. 3, the eccentric pin 65P of the control shaft 65 is positioned below, so that the control link 63 is pulled down and the lower link 60 swings clockwise around the crank pin 30P of the crankshaft 30. As a result, the upper link 61 is pushed up, and the position of the piston 11 becomes higher than the cylinder 5, and the engine E enters a high compression ratio state. On the other hand, in the second position shown in FIG. 4, the eccentric pin 65P of the control shaft 65 is located to the left (higher than the first position), so that the control link 63 is pushed up to lower link 60. Swings counterclockwise around the crankpin 30P of the crankshaft 30, the upper link 61 is pushed down, and the position of the piston 11 is lowered to a high position relative to the cylinder 5, and the engine E is in a low compression ratio state. As described above, by the rotation control of the control shaft 65, the control link 63 swings, the motion constraint condition of the lower link 60 changes, and the stroke characteristics including the top dead center position of the piston 11 change. It becomes possible to arbitrarily control the compression ratio of the engine E.

  Thus, the upper link 60, the first connecting pin 62, the lower link 60, the second connecting pin 64, and the control link 63 constitute a variable stroke link mechanism LV according to the present invention.

  As shown in FIGS. 6, 7, 9, and 10, the control shaft 65 that is connected to the control link 63 and operates the stroke variable link mechanism LV is the same as the crankshaft 30 and has a plurality of journal shafts 65 </ b> J and eccentricity. The pins 65P are alternately connected via the arm A to form a crank shape, and a cylindrical vane shaft 66 is integrally provided between the eccentric pins 65P in the center in the axial direction. The control shaft 65 is biased to one side of the lower block 41 (the front side of the engine body 1), and the journal shaft 65J is a bearing that is fixed to the lower block 41 and a plurality of connecting bolts 68 on the lower surface thereof. It is rotatably supported between the block 70. The bearing block 70 includes a vertical frame 71 that extends in the axial direction of the control shaft 65, a plurality of bearing walls 72 that stand up together with the vertical frame 71, and a central housing receiving portion 73. A bearing between the mating surfaces of the upper surfaces of the plurality of bearing walls 72 and the lower surfaces of the bearing walls 50a, 51a, 52a, 53a extending from the bearing members 50, 51, 52, 53 of the lower block 40 is provided. The journal shaft 65J of the control shaft 65 is rotatably supported by the portion.

  As will be described later, the lower portion of the housing HU provided on the central bearing member 54 is fixedly supported by a plurality of bolts 74 on the central housing receiving portion 73 formed in the bearing block 70 (see FIG. 6).

  As shown in FIGS. 6 and 7, the hydraulic actuator AC that drives the control shaft 65 is provided in the crank chamber CC of the engine body 1, and the housing HU that accommodates and supports the hydraulic drive unit includes the central bearing. The member 54 (fixed integrally with the upper block 40 and the lower block 41) is provided on the enlarging portion 58 on one side. The housing HU is formed with a short cylindrical vane chamber 80 whose both end surfaces are open, and a vane shaft 66 at the center of the control shaft 65 is passed through and accommodated in the vane chamber 80. The housing HU is rotatably supported by left and right vane bearings 81 and 82 which are other housings fixed with a plurality of bolts 83 on both sides of the housing HU, and the open side surface of the vane chamber 80 is closed by the left and right vane bearings 81 and 82. A pair of fan-shaped vane oil chambers 86 are formed between the inner peripheral surface of the vane chamber 20 and the vane shaft 66 with a phase difference of about 180 °, and the vane shafts are formed in the vane oil chambers 86. A pair of vanes 87 projecting integrally from the outer peripheral surface of the central portion of 66 is accommodated, and each vane 87 is oil-tightly divided into two control oil chambers in a fan-shaped vane oil chamber 86. By supplying and discharging hydraulic oil from a hydraulic circuit, which will be described later, to and from the two control oil chambers, the vane shaft 66, that is, the control shaft 65 can be reciprocated within a predetermined angle range.

  As described above, the housing HC of the hydraulic actuator AC that drives the control shaft 65 is compact using the central bearing member of the lower block 41 (formed separately from the lower block 41 and fixed thereto). In addition, the number of parts can be reduced, the volume occupied by the housing HC in the crank chamber CC can be reduced, and the bulk of the crankcase can be prevented from increasing.

  As shown in FIGS. 5, 7, and 9, the upper surface of the housing HU formed in the central bearing member 54 has a dovetail shape from the bearing portion 54 </ b> A of the crankshaft 30 toward the end portion on the housing HU side. An expanding flat mounting surface 90 is formed. As shown in FIG. 7, the width D1 of the mounting surface 90 in the direction of the control shaft 65 is wider than the width D2 of the housing HU. The valve unit 92 of the hydraulic control circuit of the actuator AC is fixedly supported by a plurality of bolts 91, and this valve unit 92 passes through the wall surface of the cylinder block 2 and is exposed on the upper surface thereof ( (See FIG. 1). As a result, the valve unit 92 can be firmly fixed on the mounting surface of the housing HU. The valve unit 92 is on the mounting wall surface of the cylinder block 2 and is open on all four sides. The switching operation and maintenance of the type vane actuator AC are facilitated.

  Next, a hydraulic circuit of a hydraulic actuator AC that drives and controls the stroke variable long mechanism LV will be described with reference to FIG.

  As described above, the two control oil chambers that divide the inside of the pair of fan-shaped vane oil chambers 86 formed by the vane shaft 66 of the control shaft 65 and the housing HU by the vanes 87 are connected to the oil tank T via the hydraulic circuit. An oil pump P driven by a motor M, a check valve C, an accumulator A, and an electromagnetic switching valve V are connected to the hydraulic circuit. An oil tank T, a motor M, an oil pump P, a check valve C, and an accumulator A constitute a hydraulic pressure supply device S, which is provided at an appropriate position of the engine body 1, and an electromagnetic switching valve V is provided inside the valve unit 92 described above. Is provided. The hydraulic pressure supply device S and the electromagnetic switching valve V are connected by two pipes P1 and P2, and the electromagnetic switching valve V and the hydraulic actuator AC are connected by two pipes P3 and P4. Accordingly, in FIG. 11, the vane 87 is pushed by the hydraulic pressure generated by the oil pump P that switches the electromagnetic switching valve V to the left, and the control shaft 65 rotates counterclockwise. Conversely, the electromagnetic switching valve V is moved to the right. The phase of the eccentric pin 65P of the control shaft 65 changes when the vane 87 is pushed by the hydraulic pressure generated by the oil pump P to be switched and the control shaft 65 rotates clockwise. The control link 63 of the stroke variable link mechanism LV is pivotally connected to the eccentric pin 65P of the control shaft 65 so that the control pin 65 is driven (about 90 °), and the eccentric pin 65P of the control shaft 65 is driven. As described above, the stroke variable link mechanism LV is operated by the phase change.

  As shown in FIGS. 12 and 13, a notch 5 a is formed at one place in the circumferential direction at the lower end of the cylinder 5. The lower end portion of the cylinder 5 corresponds to the lower end portion of the cylinder sleeve constituting the cylinder 5 and the lower end portion of the cylinder block 2 that supports the cylinder sleeve. To do.

  One end of the lower link 60 is formed in a bifurcated shape by the first slit 60 a, and the lower end of the upper link 61 is fitted into the first slit 60 a and is pivotally supported by the first connecting pin 62. The other end of the lower link 60 is formed in a bifurcated shape by the second slit 60b. The upper end of the control link 63 is fitted into the second slit 60b and is pivotally supported by the second connecting pin 64.

  The notch 5a is formed on the outer periphery of the lower end of the cylinder 5 on the connecting portion side of the upper link 61 and the lower link 60, and only the upper link 61 passes and the lower link 60 does not pass. It is formed. Accordingly, the circumferential width W1 of the notch 5a is smaller than the minimum width through which the upper link 61 thinner than the lower link 60 can pass, that is, the width W4 between the outer end surfaces of the lower link 60 (see FIG. 13). The width. A pair of skirt portions 11a project downward from the lower edges of the front and rear portions of the piston 11, and the circumferential width W3 of the skirt portion 11a is larger than the circumferential width W1 of the notch 5a. . Accordingly, there are two receiving surfaces 5c (shaded portions in FIG. 13) for receiving one skirt portion 11a of the piston 11 on both sides in the circumferential direction of the notch 5a of the cylinder 5.

  As described above, the notch 5a for avoiding interference with the upper link 61 is formed at the lower end portion of the cylinder 5 on the connecting portion side of the upper link 61 and the lower link 60 of the variable stroke link mechanism LV. Even if the size of E in the cylinder axis LL direction is reduced, the upper link 61 can be prevented from interfering with the lower end portion of the cylinder 5. At this time, since only the upper link 61 passes through the notch 5a and the lower link 60 thicker than the upper link 61 does not pass, the width W1 of the notch 5a can be minimized, so that the notch 5a is formed. Therefore, a decrease in the rigidity of the cylinder 5 due to this can be minimized.

  Further, since there are two receiving surfaces 5c for receiving one skirt portion 11a of the piston 11 on both sides in the circumferential direction of the notch 5a, the behavior of the piston 11 is prevented from becoming unstable due to the notch 5a. 11 is reliably prevented from being caught in the cylinder 5.

  FIGS. 14 and 15 show a second embodiment of the present invention. FIG. 14 is a view corresponding to FIG. 12, and FIG. 15 is an enlarged sectional view taken along line 15-15 of FIG.

  In the first embodiment, a notch 5a is formed on the connecting portion side of the upper link 61 and the lower link 60 in the outer periphery of the lower end portion of the cylinder 5, but in the second embodiment, the lower end of the cylinder 5 is formed. A notch 5b is formed on the connecting part side of the lower link 60 and the control link 63 in the outer periphery of the part. The number of the notches 5b is one, and the lower link 60 passes therethrough. Therefore, the circumferential width W2 of the notch 5b is smaller than the minimum width through which the lower link 60 can pass, that is, the width W5 between the outer end surfaces of the pair of counterweights of the crankshaft 30 (see FIG. 8). The width. The circumferential width W3 of the skirt portion 11a of the piston 11 is larger than the circumferential width W2 of the notch 5b. Therefore, one of the pistons 11 is disposed on both sides of the notch 5b of the cylinder 5 in the circumferential direction. There are two receiving surfaces 5c (shaded portions in FIG. 15) for receiving the skirt portion 11a.

  As described above, the notch 5b for avoiding interference with the lower link 60 is formed at the lower end portion of the cylinder 5 on the connecting portion side of the lower link 60 and the control link 63 of the variable stroke link mechanism LV. Even if the dimension of E in the cylinder axis LL direction is reduced, the lower link 60 can be prevented from interfering with the lower end portion of the cylinder 5. At this time, since the notch 5b is one of the minimum number and the size is the minimum necessary, it is possible to minimize a decrease in rigidity of the cylinder 5 due to the formation of the notch 5b.

  Further, since there are two receiving surfaces 5c that receive the other skirt portion 11a of the piston 11 on both sides in the circumferential direction of the notch 5b, the behavior of the piston 11 is prevented from becoming unstable due to the notch 5b. 11 is reliably prevented from being caught in the cylinder 5.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  In the third embodiment, a notch 5a (first notch 5a) of the first embodiment and a notch 5b (second notch) of the second embodiment are provided at the lower end of the cylinder 5. The notch 5b) is provided. The structures of the first and second notches 5a and 5b are the same as those of the first and second embodiments. Therefore, according to the third embodiment, it is possible to achieve both the operational effects of the first embodiment and the operational effects of the second embodiment.

  Further, in the third embodiment, the height H1 (see FIG. 13) of the first notch 5a in the cylinder axis LL direction is the height of the second notch 5b in the cylinder axis LL direction. It is larger than H2 (see FIG. 15). That is, since the first notch 5a has a small width W1 and a large height H1, and the second notch 5b has a large width W2 and a small height H2, the circles of the first and second notches 5a and 5b. A sufficient area of the receiving surface 5c for receiving the skirt portion 11a of the piston 11 can be ensured on both sides in the circumferential direction, thereby suppressing the behavior of the piston 11 from becoming unstable. In addition, there is no significant difference in the areas of the first and second notches 5a and 5b, thereby preventing the sliding resistance of the front and rear surfaces of the piston 11 from becoming uneven and stabilizing the behavior of the piston 11. be able to.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the first and second notches 5a and 5b are formed across the cylinder sleeve and the cylinder block 2, but may be formed only on the cylinder sleeve and not on the cylinder block 2. is there.

1 is a schematic overall perspective view of a variable stroke characteristic engine according to a first embodiment. 2 direction view of FIG. Sectional view along line 3-3 in FIG. 1 (high compression ratio state) Sectional view taken along line 4-4 in FIG. 1 (low compression ratio state) Sectional view along line 5-5 in FIG. 6-6 cross-sectional view of FIG. 7-7 enlarged vertical view of FIG. Sectional view taken along line 8-8 in FIG. 9 direction arrow view of FIG. Exploded perspective view of actuator Hydraulic circuit diagram of actuator control system Enlarged sectional view of the main part of the engine FIG. 13 is an enlarged cross-sectional view taken along line 13-13 of FIG. The figure corresponding to the said FIG. 12 based on 2nd Embodiment 14 is an enlarged cross-sectional view taken along line 15-15 in FIG. The figure corresponding to the said FIG. 12 based on 3rd Embodiment

Explanation of symbols

5 Cylinder 5a Notch, 1st notch 5b Notch, 2nd notch 5c Receiving surface 11 Piston 11a Skirt part 30 Crankshaft 60 Lower link 61 Upper link 63 Control link 65 Control shaft LV Stroke variable link mechanism H1 First cut Height H2 in the cylinder axial direction of the notch Height W1 in the cylinder axial direction of the second notch Circumferential width W2 of the first notch Circumferential width W4 of the second notch Between the outer end surfaces of the lower links Width W5 Width between the outer end surfaces of a pair of counterweights provided on the crankshaft

Claims (5)

A variable stroke link mechanism (LV) that connects the piston (11) slidably fitted to the cylinder (5), the crankshaft (30), and the control shaft (65) is swung to the crankshaft (30). A lower link (60) supported movably, an upper link (61) for connecting the lower link (60) to the piston (11), and a control link for connecting the lower link (60) to the control shaft (65) ( 63), the variable stroke characteristic engine
A notch (5a) through which the upper link (61) passes and the lower link (60) does not pass is passed to the lower end of the connecting part side cylinder (5) that connects the upper link (61) and the lower link (60). A variable stroke characteristic engine characterized by being formed. A variable stroke link mechanism (LV) that connects the piston (11) slidably fitted to the cylinder (5), the crankshaft (30), and the control shaft (65) is swung to the crankshaft (30). A lower link (60) supported movably, an upper link (61) for connecting the lower link (60) to the piston (11), and a control link for connecting the lower link (60) to the control shaft (65) ( 63), the variable stroke characteristic engine
It is characterized in that a single notch (5b) through which the lower link (60) passes is formed at the lower end of the cylinder (5) on the connecting portion side connecting the lower link (60) and the control link (63). Variable stroke characteristics engine.   On both sides in the circumferential direction of the notch (5a), there are receiving surfaces (5c) for receiving the skirt portion (11a) of the piston (11), and the circumferential width (W1) of the notch (5a). The stroke characteristic variable engine according to claim 1, wherein is smaller than a width (W4) between outer end faces of the lower link (60).   On both sides in the circumferential direction of the notch (5b), there are receiving surfaces (5c) for receiving the skirt portion (11a) of the piston (11), and the circumferential width (W2) of the notch (5b). The stroke characteristic variable engine according to claim 2, wherein is smaller than a width (W5) between outer end surfaces of a pair of counterweights provided on the crankshaft (30). A variable stroke link mechanism (LV) that connects the piston (11) slidably fitted to the cylinder (5), the crankshaft (30), and the control shaft (65) is swung to the crankshaft (30). A lower link (60) supported movably, an upper link (61) for connecting the lower link (60) to the piston (11), and a control link for connecting the lower link (60) to the control shaft (65) ( 63) In the variable stroke characteristic engine configured as
A first notch through which the upper link (61) does not pass and the lower link (60) does not pass through the lower end portion of the cylinder (5) on the side of the first connecting portion that connects the upper link (61) and the lower link (60). A single second notch (5b) through which the lower link passes at the lower end of the cylinder (5) on the second connecting part side that forms (5a) and connects the lower link (60) and the control link (63). And a receiving surface (5c) for receiving the skirt portion (11a) of the piston (11) is present on both sides in the circumferential direction of the first and second notches (5a, 5b). The circumferential width (W1) of the notch (5a) is narrower than the circumferential width (W2) of the second notch (5b), and the height of the first notch (5a) in the cylinder axis direction is high. (H1) is in the cylinder axial direction of the second notch (5b). Being higher than the (H2), stroke characteristic variable engine.

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