JP2008088889A - Bearing structure of control shaft in variable stroke characteristic engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the supporting rigidity of the bearing part of a control shaft operating a variable stroke link mechanism, and to increase the variable mount of the stroke of a piston, in a variable stroke characteristics engine varying the moving stroke of the piston. <P>SOLUTION: In this bearing structure of the control shaft in the variable stroke characteristics engine, the piston and a crankshaft 30 are coupled to the control shaft 65 through the variable stroke link mechanism, and the control shaft 65 is driven by an actuator provided on the control shaft 65 to vary the moving stroke of the piston. The bearing wall part 52a of a bearing member 52 supporting the control shaft 65 is made from material having higher rigidity than that of a crank case 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, a piston and a crankshaft are connected to a control shaft through a stroke variable link mechanism, and an actuator is provided on the control shaft. The actuator is driven by the actuator to operate the stroke variable link mechanism to The present invention relates to a bearing structure of a control shaft in a variable stroke characteristic engine in which a moving stroke is variable.

Conventionally, 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, the other An engine having a variable stroke link mechanism comprising a control link whose end is slidably connected to a control shaft, wherein the control shaft is driven by a drive source such as a motor provided therein to vary the compression ratio of the piston. Is known (see Patent Document 1 below).
JP 2002-47955 A

  By the way, in such an engine, during operation, an excessive load is applied to the bearing portion of the control shaft, and the load fluctuation is large. Therefore, when high support rigidity cannot be obtained in the bearing portion, the engine operation is performed. There are problems that the conditions are limited and that the stroke variable amount is limited to a narrow range.

  However, in the thing of the said patent document 1, since the special technical consideration for raising the support rigidity is not made | formed to the bearing part of the control shaft, it has not reached to solve the said problem.

  The present invention has been made in view of such a situation, and has a control shaft bearing structure in a novel variable stroke characteristic engine that solves the above-described problems by improving the support rigidity of the control shaft as much as possible with a simple configuration. The main purpose is to provide.

  In order to achieve the above object, according to the present invention, a piston and a crankshaft are connected to a control shaft via a stroke variable link mechanism, and the control shaft is driven by an actuator. Is a bearing structure of a control shaft in a variable stroke characteristic engine in which the moving stroke of the piston is made variable by operating the at least part of the bearing wall supporting the control shaft, which is higher in rigidity than the material constituting the crankcase It is characterized by being composed of the material.

  In order to achieve the above object, the invention according to claim 2 is the one according to claim 1, wherein the bearing wall portion of the control shaft made of a highly rigid material is provided via the variable stroke link mechanism. It is characterized by being provided at the maximum load position generated on the control shaft.

  In order to achieve the above object, according to a third aspect of the present invention, in the first or second aspect of the invention, the control shaft is disposed below the crankshaft, and the stroke is variable on the bearing wall. A maximum upward load is generated via the link mechanism, and at least a part of the upper half of the bearing wall is made of a material having higher rigidity than a material constituting the crankcase. It is a feature.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the third aspect of the present invention, the bearing wall portion of the control shaft formed of the high-rigidity material is positioned at both ends in the control shaft direction. It is provided in the bearing wall except the bearing wall which carries out.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the first, second, third or fourth aspect, the bearing wall made of the high-rigidity material is cast into a crankcase. It is a member.

  In order to achieve the above object, according to a sixth aspect of the present invention, in the fifth aspect of the present invention, at least a part of a bearing wall of the crankshaft is made of a highly rigid material and is cast into a crankcase. The crankshaft has a highly rigid bearing wall portion and a control shaft bearing wall portion formed of a highly rigid material.

  In order to achieve the above object, according to a seventh aspect of the present invention, there is provided the invention according to the fifth or sixth aspect, wherein the communication passage that constitutes the engine body and communicates the cylinder head and the crankcase is the high-rigidity material. The engine main body is provided at a position avoiding the bearing wall portion.

  According to the first aspect of the present invention, at least a part of the bearing wall that supports the control shaft is made of a material that is higher in rigidity than the material that forms the crankcase. The support rigidity can be increased, and the operating conditions of the engine and the variable amount of the stroke of the piston can be expanded.

  According to the second aspect of the present invention, at least a part of the bearing wall of the control shaft, which is made of a highly rigid material, is provided at the maximum load position generated in the bearing wall. The support rigidity of the bearing portion can be further increased.

  According to the third aspect of the present invention, the bearing wall of the control shaft has the upper half portion of the bearing wall where the maximum load is generated made of a material having higher rigidity than the material constituting the crankcase. The increase in the weight of the bearing portion can be suppressed while ensuring the high support rigidity of the bearing wall of the control shaft.

  According to the fourth aspect of the present invention, since the highly rigid bearing wall portion of the control shaft is provided on the bearing wall excluding the bearing walls positioned at both ends in the control shaft direction, one layer of the bearing portion of the control shaft is provided. The increase in the weight of the engine body can be suppressed and the increase in size of the engine body in the control axis direction can be suppressed.

  According to the fifth aspect of the present invention, since the bearing wall portion made of a highly rigid material is a cast member cast into the crankcase, the increase in the number of parts can be suppressed and the size can be reduced. In addition, the cost can be reduced.

  According to the sixth aspect of the present invention, at least a part of the bearing wall of the crankshaft is made of a highly rigid material and cast into the crankcase, the highly rigid bearing wall portion of the crankshaft, Since the bearing wall portion of the control shaft formed of a rigid material is integrally formed, both the support rigidity of the crankshaft and the control shaft can be greatly increased.

  According to the seventh aspect of the present invention, the communication path that connects the cylinder head and the crankcase, which constitutes the engine body, is located in the engine body at a position that avoids the bearing wall portion made of the highly rigid material. Since it is provided, it is possible to easily form a communication passage used for an oil return passage, a blow-by gas passage and the like while ensuring a high support rigidity of the control shaft.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on examples of the present invention shown in the accompanying drawings.

  First, a first embodiment of the present invention will be described with reference to FIGS.

  1 is a schematic overall perspective view of a variable stroke characteristic engine, FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1, FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1 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. 2, and FIG. 6 is a sectional view taken along line 6-6 in FIG. 7 is a longitudinal view taken along line 7-7 in FIG. 5, FIG. 8 is a sectional view taken along line 8-8 in FIG. 5, and FIG. 9 is a sectional view taken along line 9-9 in FIG. 10 is a cross-sectional view taken along line 10-10 in FIG. 3, FIG. 11 is a perspective view taken along arrow 11 in FIG. 5, FIG. 12 is an exploded perspective view of the vane hydraulic actuator, and FIG. FIG. 14 is a hydraulic circuit diagram of the control system of the vane type hydraulic actuator.

  1 to 4, a 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 arranged laterally with respect to the traveling direction of the automobile). ). When the engine E is mounted on a vehicle, as shown in FIG. 2, the cylinder E 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 a part of the lower crankcase is formed on the lower surface of the lower block 41 (lower crankcase). The oil pan 10 is integrally coupled.

  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 to open and close the intake valve 16 and the exhaust valve 17 at a predetermined timing. Can be operated.

  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 5, and a spark plug 32 is inserted into the plug insertion cylinder 31.

  The plurality of intake ports 14 corresponding to the four cylinders 5 are opened toward the front surface of the engine body 1, that is, 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 forward than the cylinder 5 part of the cylinder block 2. A variable stroke link mechanism LV (described later) and a vane hydraulic actuator that drives the variable stroke link mechanism LV are provided in the crank chamber CC of the extended portion 36 so as to make the moving stroke of the piston 11 variable. AC (described later) is provided.

  As shown in FIGS. 2, 3 and 5, 6, a lower block 41 is fixed to the lower surface of the upper block 40 integrally formed at the lower portion of the cylinder block 2 with a plurality of connecting bolts 42. The journal shaft 30J of the crankshaft 30 is rotatably supported by a plurality of journal bearing portions 45 formed on the mating surfaces of the upper block 40 and the lower block 41 (see FIG. 10).

  As shown in FIG. 5, the lower block 41 is made of an aluminum alloy and cast into 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. In the middle part, left and right middle bearing members 52 and 53 are provided, and in the center, a central bearing member 54 (a housing HU described later is integrally formed) as a bearing cap is provided. The journal shaft 30J of the crankshaft 30 is rotatably supported by the bearing members 50 to 54.

  As shown in FIGS. 5, 6, and 9, the central bearing member, that is, the bearing cap 54, is separately formed from the lower block 41, and is cast from a highly rigid material such as an iron material or a fiber reinforced composite material (FRM). The bearing cap 54 is firmly fixed to the side surface of the lower block 41 by a plurality of bearing cap tightening bolts 56, and the bearing cap 54 is also firmly fixed to the lower surface of the upper block 40 by a plurality of other bearing cap tightening bolts 57. Has been. One side portion of the bearing cap 54 that is biased from the bearing portion 54A of the crankshaft 30 toward one side (the front side of the engine body 1) is an enlarging portion 58 that has an enlarged vertical width and is thick. The portion 58 is integrally provided with a housing HU of a vane type hydraulic actuator AC, which will be described in detail later.

  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. A crank that 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 shaft 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 provided with a vane type hydraulic actuator AC (described later in detail) coaxially therewith, and the control shaft 65 is rotated within a predetermined angle range (about 90 degrees) by driving the vane type hydraulic actuator. The control link 63 is driven to swing by the phase shift 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 crank pin 30P of the crankshaft 30, the upper link 61 is pushed down, and the position of the piston 11 is lowered with respect to the cylinder 5, and the engine E enters 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.

  Accordingly, the upper link 61, 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 to 12, the control shaft 65 that is connected to the control link 63 and operates the variable stroke link mechanism LV is similar to the crankshaft 30 and includes a plurality of journal shafts 65J and eccentric pins 65P that support the arm 65A. Are connected to each other through a crank shape. A cylindrical vane shaft 66 of the vane type hydraulic actuator AC is integrally and coaxially formed at the center in the axial direction, and the eccentric pins 65 of the control shaft 65 are directly at the eccentric positions on both side surfaces of the vane shaft 66. It is fixed. The control shaft 65 is biased to one side of the lower block 41 (the front side of the engine body 1) and is provided in parallel to and below the crankshaft 30. The journal shaft 65J is connected to the lower block 41 and the lower block 41. It is rotatably supported between a bearing block 70 fixed to the lower surface with a plurality of connecting bolts 68.

  As shown in FIGS. 6 to 11, the bearing block 70 that supports the control shaft 65 is integrated with a connecting member 71 that extends in the axial direction of the control shaft 65, and the connecting member 71 that is spaced apart in the longitudinal direction. A plurality of bearing walls 72 standingly coupled to each other and a central housing receiving portion 73 provided at a central portion in the longitudinal direction of the connecting member 71, which are cast into a block shape so as to ensure high rigidity. The bearing portion formed on the mating surface of the upper surface of the bearing wall 72 and the lower surface of the bearing walls 50a, 51a, 52a, 53a extended from the bearing members 50, 51, 52, 53 of the lower block 41 is described above. As described above, a plurality of journal shafts 65J of the control shaft 65 are rotatably supported. Further, as shown in FIG. 9, the central housing receiving portion 73 is formed in a concave shape downward in a direction away from the housing HU, and the lower portion of the housing HU is formed on the central housing receiving portion 73 with a plurality of fastening bolts. 74 is fastened. Therefore, the housing HU of the hydraulic actuator AC is integrally fastened and supported by the bearing block 70 that supports the control shaft 65.

  As shown in FIGS. 6, 9, and 11, the vane hydraulic actuator AC that drives the control shaft 65 is provided at the center of the control shaft 65, and its housing HU is a central bearing member, that is, a bearing cap 54. (It is integrally fixed to the upper block 40 and the lower block 41). A short cylindrical vane chamber 80 whose both end surfaces are opened is formed in the central portion of the housing HU in the axial direction, and the vane shaft 66 integral with the control shaft 65 is accommodated in the vane chamber 80. Yes. A pair of vanes 87 are integrally formed at the central portion in the axial direction of the outer peripheral surface of the vane shaft 66 with a phase difference of about 180 °. The left and right side portions of the vane shaft 66 in the axial direction (slightly smaller in diameter than the central portion) are fixed to the left and right cover members 81 and 82 by a plurality of bolts 83 on both side portions of the housing HU via surface bearings. It is supported rotatably. The opening side surface of the housing HU is closed by the cover members 81 and 82. A pair of fan-shaped vane oil chambers 86 are defined between the inner peripheral surface of the vane chamber 80 and the outer peripheral surface of the vane shaft 66 with a phase difference of about 180 °. In addition, a pair of vanes 87 are respectively accommodated, and the outer peripheral surfaces thereof are slidably contacted with the inner peripheral surfaces of the vane oil chambers 86 through packings, and each vane 87 passes through the fan-shaped vane oil chamber 86. It is oil-tightly divided into two control oil chambers 86a and 86b.

  As shown in FIGS. 5, 7, and 8, among the bearing walls 50 a to 54 a of the plurality of bearing members 50 to 54 of the lower block 41, the bearing walls 52 a and 53 a of the left and right intermediate bearing members 52 and 53 have high rigidity. The bearing wall portions 52b and 53b are integrally cast and formed on both outer surfaces in the width direction of the bearing wall portions 52b and 53b on the concave and convex surfaces 55, and cast with the bearing walls 52a and 53a. Bond strength is increased. For example, when the base material of the bearing members 52 and 53 is formed of an aluminum alloy material, the bearing wall portions 52b and 53b are formed of an iron material or a fiber composite reinforcing material (FRM).

  As shown in FIGS. 7 and 8, a semicircular lower half portion of the journal bearing portion 45 of the crankshaft 30 is formed on one side of the upper surface of the highly rigid bearing wall portions 52b and 53b, and the other side of the lower surface thereof. Is formed with a semicircular upper half of the journal bearing portion 67 of the control shaft 65.

  By the way, during operation of the engine E, the explosion variable combustion causes the stroke variable link mechanism LV to operate, so that the control shaft 65 has a connection point between the lower link 60 and the control link 63, that is, the direction of the second connection pin 64. A maximum upward load is generated through the control link 63 (in the direction of the arrow a in FIGS. 7 and 8) (when the engine E is operated at the lowest low compression state, the maximum load becomes the largest), and Since a downward maximum load is generated on the crankshaft 30, each of the high-rigidity bearing wall portions 52b and 53b is disposed to receive the maximum load as described above, and the crankshaft 30 and the control shaft 65 Support rigidity can be increased.

  As shown in FIG. 13, the highly rigid bearing walls 52b and 53b have a crankshaft direction width of the support region of the crankshaft 30 and the maximum load generation region of the control shaft 65 as d1, and the remaining regions in the same direction. When the width is d2, d1> d2. By doing so, it is possible to reduce the weight of the highly rigid bearing wall portions 52b and 53b while ensuring sufficient support rigidity in the maximum load generation region, and thus to reduce the weight of the bearing portions of the crankshaft 30 and the control shaft 65. It is done.

  Further, the rigidity of the crankshaft 30 and the control shaft 65 is ensured by casting the highly rigid bearing wall portions 52b and 53b specifically for the bearing walls 52a and 53a of the left and right intermediate bearing members 52 and 53. However, an increase in size and weight of the lower block 41 can be suppressed, and further an increase in the size of the engine body 1 in the direction of the control shaft 65 is suppressed.

  The bearing block 70 fastened to the lower surface of the lower block 41 and supporting the control shaft 65 in cooperation with the lower block 41 may be formed of the same material as the base material of the lower block 41. You may form with the same material as the said highly rigid bearing wall part 52b, 53b.

  As shown in FIGS. 5, 9, 11, and 12, the upper surface of the housing HU formed on the central bearing member, that is, the bearing cap 54, is directed from the bearing portion 54 </ b> A of the crankshaft 30 toward the end portion on the housing HU side. A flat mounting surface 90 extending in a dovetail shape is formed. As shown in FIG. 9, 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. A valve unit 92 that accommodates the electromagnetic valve V (FIG. 11) of the hydraulic circuit of the vane hydraulic actuator AC is fixedly supported on the surface 90 with a plurality of bolts 91. It penetrates a wall surface and is arrange | positioned in the exposed state on the upper surface (refer FIG. 1).

  As shown in FIGS. 2, 5 and 7, 8, provided in the engine body 1, the cylinder head 3 communicates with the crankcase 4, and an oil return passage, blowby gas passage, or oil passage, in the crankcase 4 The communication passage 38 used for the press-fitting fluctuation mitigation passage is provided at a position avoiding the high-rigidity bearing wall portions 52b and 53b, and the communication passage 38 is provided with the high-rigidity bearing wall portion 52b, The support rigidity by 53b is not lowered, and the passage 38 is easily formed.

  The communication passage 38 is provided on the opposite side of the control shaft 65 with the crankshaft 30 in between, so that the flow of oil and blow-by gas flowing through the communication passage 38 operates the variable stroke link mechanism LV. There is no worry to be disturbed by.

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

  As described above, 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 is divided into two control oil chambers 86a and 86b by the vanes 87, respectively. The control oil chambers 86a and 86b are connected to the oil tank T via a hydraulic circuit described later. 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 control oil chambers 86a and 86b of the vane hydraulic actuator AC are two pipes P3 and P4. Connected with. Therefore, in FIG. 14, when the electromagnetic switching valve V is switched to the right position, the hydraulic oil generated by the oil pump P is supplied to the control oil chamber 86b, and the vane 87 is pushed by the hydraulic pressure to rotate the control shaft 65 clockwise. When the electromagnetic switching valve V is switched to the left position, the hydraulic oil generated by the oil pump P is supplied to the control oil chamber 86a, and the vane 87 is pushed by the hydraulic pressure, so that the control shaft 65 is counterclockwise. By rotating in the direction, the phase of the eccentric pin 65P of the control shaft 65 changes. As described above, the control link 63 of the variable stroke link mechanism LV is pivotally connected to the eccentric pin 65P of the control shaft 65 so that the control shaft 65 can be swung. The stroke variable link mechanism LV is operated by the phase change of the eccentric pin 65P.

  By the way, according to the first embodiment, the bearing wall portions 52b and 53b of the bearing walls 52a and 53a of the lower block 41 that support the control shaft 65 are made of a material having higher rigidity than the material constituting the crankcase 4. Therefore, the support rigidity of the bearing portion of the control shaft 65 can be significantly increased, and the variable amount of the stroke of the piston 11 can be increased. In particular, by providing the highly rigid bearing wall portions 52b and 53b at the maximum load position generated in the bearing portion of the control shaft 65, the support rigidity of the bearing portion of the control shaft 65 can be further increased.

  The control shaft 65 is disposed below the crankshaft 30, and the bearing walls 50a to 54a generate a maximum upward load via the variable stroke link mechanism LV. Since the upper half of the bearing wall portions 52b and 53b is formed of a material having higher rigidity than the material constituting the crankcase 4, the weight of the bearing portion is secured while ensuring high support rigidity of the control shaft 65. Can be suppressed.

  Further, since the highly rigid bearing wall portions 52b and 53b of the control shaft 65 are provided on the bearing walls 52a and 53a excluding the bearing walls 50a and 51a located at both ends in the control shaft direction, the bearing portion of the control shaft 65 is provided. Further increase in the weight of the engine body 1 can be suppressed, and an increase in the size of the engine body 1 in the control axis direction can be suppressed.

  Furthermore, since the bearing wall portions 52b and 53b made of a highly rigid material are cast members cast into the crankcase 4, an increase in the number of components can be suppressed, and the size and cost can be reduced. Can be achieved.

  Further, at least a part of the bearing walls 50 to 54 of the crankshaft 30 is made of a highly rigid material and cast into the crankcase 4, and the highly rigid bearing wall portions 52 b and 52 b of the crankshaft 30, Since the bearing wall portions 52b and 53b of the control shaft formed of a rigid material are integrally formed, both the support rigidity of the crankshaft 30 and the control shaft 65 can be significantly increased.

  Furthermore, the communication passage 38 that communicates the cylinder head 3 and the crankcase 4 that constitutes the engine body 1 is located in the engine body 1 at a position that avoids the bearing wall portions 52b and 53b made of the highly rigid material. Accordingly, the communication passage 38 used for an oil return passage, a blow-by gas passage, or the like can be easily formed while ensuring a high support rigidity of the control shaft 65.

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

  FIG. 15 is a diagram corresponding to FIG. 5 of the first embodiment, and the same reference numerals are given to the same elements as those of the first embodiment.

  In the second embodiment, among the plurality of bearing walls 50a to 54a provided in the lower block 41, the bearing walls 50a and 51a supporting both ends of the crankshaft 30 and the control shaft 65 are bearing walls made of a highly rigid material. The parts 50b and 51b are cast and formed, and these bearing wall parts 50b and 51b have the same structure as that of the first embodiment, and can increase the support rigidity of the crankshaft 30 and the control shaft 65. In particular, since both end portions of the control shaft 30 and the control shaft 65 are supported by the highly rigid bearing wall portions 50b and 51b, the support span can be made longer, and the support rigidity is further enhanced.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the Example, A various Example is possible within the scope of the present invention.

  For example, in the above embodiment, the case where the present invention is a variable compression ratio engine that changes the top dead position of the piston by changing the phase of the eccentric pin of the control shaft has been described. Is also applicable. In the above-described embodiment, a case has been described in which high-rigidity bearing wall portions are provided in some of the plurality of bearing walls that support the control shaft. However, high-rigidity bearing wall portions are provided in all of these bearing walls. May be.

Schematic overall perspective view of engine with variable stroke characteristics 2 arrow view of FIG. Sectional view along line 3-3 in FIG. 1 (high compression ratio state) Sectional view along line 4-4 in FIG. 1 (low compression ratio state) Sectional view along line 5-5 in FIG. Cross-sectional view along line 6-6 in FIG. Vertical view along line 7-7 in FIG. Sectional drawing which follows the 8-8 line of FIG. Sectional drawing which follows the 9-9 line of FIG. Sectional drawing which follows the 10-10 line of FIG. 11 perspective view of FIG. Disassembled perspective view of vane hydraulic actuator Sectional view along line 13-13 in FIG. Hydraulic circuit diagram of the control system of the vane hydraulic actuator FIG. 5 is a diagram corresponding to FIG. 5 according to the second embodiment of the present invention.

Explanation of symbols

1 ... Engine body 3 ... Cylinder head 4 ... Crankcase 11 ... Piston 30 ... Crankshaft 38 ... Communication path 50a ... Bearing wall 51a ... Bearing wall 52a ... Bearing wall 53a ... Bearing wall 50b・ ・ ・ ・ ・ Bearing wall (high rigidity)
51b ... Bearing wall (high rigidity)
52b ・ ・ ・ ・ ・ ・ Bearing wall (high rigidity)
53b ... ・ Bearing wall (high rigidity)
65 ········ Control shaft AC ··············· Vane hydraulic actuator LV

Claims (7)

The piston (11) and the crankshaft (30) are connected to a control shaft (65) via a variable stroke link mechanism (LV), and the control shaft (65) is driven by an actuator (AC) to change the stroke. A control shaft bearing structure in a variable stroke characteristic engine that operates a link mechanism (LV) to change a moving stroke of the piston (11),
A stroke characterized in that at least a part of the bearing walls (50a to 53a) supporting the control shaft (65) is made of a material having rigidity higher than that of the crankcase (4). Bearing structure of the control shaft in the variable characteristic engine.   The bearing wall portions (52a, 53b; 50b, 51b) of the control shaft (65), which are made of a highly rigid material, are the maximum generated on the control shaft (65) via the stroke variable link mechanism (LV). 2. A bearing structure for a control shaft in a variable stroke characteristic engine according to claim 1, wherein the bearing structure is provided at a load position.   The control shaft (65) is disposed below the crankshaft (30), and a maximum upward load is generated on the bearing walls (51a to 53a) via the stroke variable link mechanism (LV). The upper half of at least a part of the bearing walls (51a to 53a) is made of a material having higher rigidity than the material constituting the crankcase (4). Item 3. The bearing structure of the control shaft in the variable stroke characteristic engine according to item 1 or 2.   The bearing walls (52b, 53b) of the control shaft (65) formed of the high-rigidity material are bearing walls (52a, 52a) excluding the bearing walls (50a, 51a) located at both ends in the control axis direction. The bearing structure of the control shaft in the variable stroke characteristic engine according to claim 3, wherein   The bearing walls (52b, 53b; 50b, 51b) made of the high-rigidity material are cast members that are cast into the crankcase (4). Bearing structure of the control shaft in the described stroke characteristic variable engine.   At least a part of the bearing walls (51a to 53a) of the crankshaft (30) is made of a highly rigid material and cast into the crankcase (4). The highly rigid bearing wall of the crankshaft (30) The part (52b, 53b; 50b, 51b) and the bearing wall part (52b, 53b; 50b, 51b) of the control shaft (65) formed of a highly rigid material are formed integrally. The bearing structure of the control shaft in the variable stroke characteristic engine according to claim 5.   The communication passage (38) composing the cylinder head (3) and the crankcase (4) constituting the engine body (1) is a bearing wall portion (52b, 53b; 50b, 51b) made of the highly rigid material. The bearing structure of the control shaft in the variable stroke characteristic engine according to claim 5 or 6, characterized in that it is provided in the engine body (1) at a position avoiding the above.

Images