Compression ratio changing device and engine

Abstract

To enable suppression of damage to a first rod extending from a piston of an engine or to a movable piece.SOLUTION: A compression ratio changing device for changing the compression ratio of an engine, comprises: a first rod extending from a piston of the engine, the first rod having a first tip end surface that is inclined so as to approach the piston as the first tip end surface goes outward in the radial direction; a second rod extending from a crankshaft of the engine; a movable piece including a first contact surface, which abuts on the first tip end surface of the first rod and is inclined so as to approach the piston toward an outer side in the radial direction, and a second contact surface that abuts on a second tip end surface of the second rod; a push-in member configured to move the first rod in the extension direction of the first rod by moving the movable piece in the radial direction while abutting the first contact surface on the first tip end surface of the first rod and abutting the second contact surface on the second tip end surface of the second rod; and a resistance force application mechanism for applying resistance force to the first rod against moving force that moves the first rod to the piston side in the extension direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a compression ratio changing device for changing the compression ratio of an engine, and an engine equipped with this compression ratio changing device. [Background technology]

[0002] For example, Patent Document 1 discloses a compression ratio changing device that changes the compression ratio of an engine by moving a wedge (movable piece) in the radial direction to push and move a piston rod. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-8885 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if an unexpected drop in cylinder pressure or an increase in friction between the piston and the cylinder liner occurs, the piston rod may separate from the movable piece. If the piston rod separates from the movable piece, for example, the piston rod may fall, causing a collision between the piston rod and the movable piece, resulting in damage to at least one of the piston rod and the movable piece.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a compression ratio change device that can suppress damage to a first rod (piston rod) extending from a piston of an engine or to a movable piece, and an engine equipped with this compression ratio change device. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a compression ratio change device according to the present disclosure is a compression ratio change device for changing the compression ratio of an engine, and includes: a first rod extending from a piston of the engine, the first rod having a first tip end surface that is inclined so as to approach the piston as it extends radially outward; a second rod extending from a crankshaft of the engine; a movable piece including a first abutment surface that abuts against the first tip end surface of the first rod and is inclined so as to approach the piston as it extends radially outward; and a second abutment surface that abuts against the second tip end surface of the second rod; a pushing member configured to move the first rod in the extension direction by moving the movable piece in the radial direction while bringing the first abutment surface into abutment with the first tip end surface of the first rod and bringing the second abutment surface into abutment with the second tip end surface of the second rod; and a resistance force applying mechanism that applies to the first rod a resistance force that resists a moving force that moves the first rod toward the piston in the extension direction of the first rod. [Effects of the Invention]

[0007] According to the compression ratio changing device and engine of the present disclosure, damage to the first rod (piston rod) or the movable piece extending from the piston of the engine can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a compression ratio changing device according to a first embodiment. [Figure 2] 2 is a diagram schematically showing the configuration of a movable piece according to the first embodiment. FIG. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a drive mechanism according to the first embodiment. [Figure 4] FIG. 4 is a perspective view schematically showing another example of the configuration of the drive mechanism according to the first embodiment. [Figure 5] 3A to 3C are diagrams illustrating the configuration of a resistance force applying mechanism according to the first embodiment. [Figure 6]5A and 5B are diagrams for explaining a third zigzag shape and a fourth zigzag shape according to the first embodiment. [Figure 7] FIG. 4 is a diagram illustrating a schematic configuration of a compression ratio changing device according to a second embodiment. [Figure 8] FIG. 10 is a diagram illustrating a schematic configuration of a compression ratio changing device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a compression ratio changing device and an engine according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, but does not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0010] The compression ratio changing device according to the present disclosure changes the compression ratio of an engine. The engine is not particularly limited, and may be a diesel engine or a gas engine.

[0011] First Embodiment FIG. 1 is a diagram schematically illustrating the configuration of a compression ratio changing device 1A(1) according to a first embodiment. First, the configuration of an engine 100 in which the compression ratio changing device 1A is provided will be described. As shown in FIG. 1, the engine 100 includes the compression ratio changing device 1A, a piston 102, a cylinder liner 104 configured to accommodate the piston 102 so as to be slidable along an axial direction Oc, and a crankshaft 110 connected to the piston 102 and converting the reciprocating motion of the piston 102 into rotational motion. A combustion chamber 101 of the engine 100 is defined by the piston 102, a cylinder head (not shown), and the cylinder liner 104.

[0012] (composition) The configuration of a compression ratio changing device 1A according to the first embodiment will be described below. As shown in Fig. 1, the compression ratio changing device 1A includes a first rod 2, a second rod 4, a plurality of movable pieces 6, a pushing member 8, a drive mechanism 9, and a resistance force applying mechanism 10A (10).

[0013] The first rod 2 has a rod shape and extends from the piston 102 of the engine 100. In the embodiment illustrated in Fig. 1, the first rod 2 is a piston rod having a base end connected to an opposite surface 102a of the piston 102 opposite to the surface facing the combustion chamber 101.

[0014] Hereinafter, the direction in which the first rod 2 extends will be referred to as the "extension direction D1." The piston 102 side of the extension direction D1 will be referred to as one side of the extension direction D1, and the side opposite the piston 102 will be referred to as the other side of the extension direction D1. A direction that is perpendicular to the extension direction D1 and passes through the center line O of the first rod 2 will be referred to as the "radial direction D2," a direction toward the center line O will be referred to as the inner side of the radial direction D2, and a direction away from the center line O will be referred to as the outer side of the radial direction D2. The circumferential direction of the first rod 2 centered on the center line O will be referred to as the "circumferential direction D3."

[0015] As shown in FIG. 1 , the first rod 2 is inclined such that the first tip surface 12 on the other side of the extension direction D1 approaches the piston 102 as it moves outward in the radial direction D2. The first tip surface 12 extends linearly from the outer edge 12a to a center position P1 through which the center line O passes. The smaller of the angles formed by the first tip surface 12 and an imaginary line La extending in the radial direction D2 is defined as the inclination angle θ1 of the first tip surface 12. The first tip surface 12 may be a conical surface, or a surface formed by multiple planes intersecting each other, such as a polygonal pyramidal surface, a polygonal truncated pyramidal surface, or a wedge-shaped surface. In some embodiments, the first tip surface 12 is a polygonal pyramidal surface, and the first abutment surface 22, which will be described later, is a flat surface. This configuration increases the area over which the first tip surface 12 abuts against the first abutment surface, thereby improving the stability of the first rod 2, for example, by suppressing tilting of the first rod 2.

[0016] The second rod 4 extends from the crankshaft 110 of the engine 100. In the embodiment illustrated in FIG. 1, the second rod 4 is a connecting rod whose base end 4a is attached to the crankshaft 110 and connects the piston 102 to the crankshaft 110. In the embodiment illustrated in FIG. 1, the second rod 4 includes a wall portion 20 that extends from an outer edge portion 18 of a second tip surface 16 on one side in the extension direction D1 of the second rod 4 toward the piston 102. The wall portion 20 covers a part of the pushing member 8 (a base portion 32 described below) from the outside in the radial direction D2.

[0017] The movable piece 6 includes a first abutment surface 22 that abuts against the first tip surface 12 of the first rod 2 and is inclined so as to approach the piston 102 as it extends outward in the radial direction D2, and a second abutment surface 24 that abuts against the second tip surface 16 of the second rod 4. The first tip surface 12 of the first rod 2, the first abutment surface 22 of the movable piece 6, the second tip surface 16 of the second rod 4, and the second abutment surface 24 of the movable piece 6 are all flush with each other. The first tip surface 12 of the first rod 2 and the first abutment surface 22 of the movable piece 6 are inclined with respect to a direction perpendicular to the extension direction D1 (radial direction D2). If the smaller angle formed by the first abutment surface 22 of the movable piece 6 and the imaginary line La is defined as the inclination angle θ2 of the first abutment surface 22, the relationship θ2-1 degrees < θ1 < θ2+1 degrees is satisfied. The second tip surface 16 of the movable piece 6 and the second contact surface 24 of the second rod 4 are not inclined or are barely inclined with respect to the direction (radial direction D2) perpendicular to the extending direction D1.

[0018] 1, the movable piece 6 further includes a receiving surface 26 that is continuous with the first contact surface 22 and extends outward in the radial direction D2, an inner surface 28 that connects the first contact surface 22 and the second contact surface 24, and an outer surface 30 that connects the receiving surface 26 and the second contact surface 24 and is positioned outward in the radial direction D2 than the inner surface 28. The receiving surface 26 is inclined so as to approach the piston 102 as it moves inward in the radial direction D2. The inner surface 28 and the outer surface 30 extend along the extension direction D1.

[0019] FIG. 2 is a view schematically illustrating a configuration of a movable piece 6 according to the first embodiment, taken from the perspective of A in FIG. 1. In the first embodiment, as illustrated in FIG. 2, the multiple movable pieces 6 include a first movable piece 6A(6), a second movable piece 6B(6), a third movable piece 6C(6), and a fourth movable piece 6D(6), which are spaced apart from one another along the circumferential direction D3. The first movable piece 6A is disposed on the opposite side of the center line O from the fourth movable piece 6D. The first movable piece 6A is disposed symmetrically with the fourth movable piece 6D about the center line O. Similarly, the second movable piece 6B is disposed on the opposite side of the center line O from the third movable piece 6C. The second movable piece 6B is disposed symmetrically with the third movable piece 6C about the center line O. Note that, although the compression ratio change device 1 includes four movable pieces 6 in the first embodiment, the present disclosure does not limit the number of movable pieces 6 to this embodiment. The number of movable pieces 6 is any number equal to or greater than two, and may be an odd number.

[0020] The pushing member 8 is configured to move the movable piece 6 along the radial direction D2 while bringing the first contact surface 22 into contact with the first tip surface 12 of the first rod 2 and the second contact surface 24 into contact with the second tip surface 16 of the second rod 4. Furthermore, the pushing member 8 is configured to move the first rod 2 along the extension direction D1 by moving the movable piece 6 in the radial direction D2.

[0021] In the first embodiment, as illustrated in FIG. 1 , the pushing member 8 has a cylindrical shape extending along the extension direction D1, and is provided with a through hole 36 through which the first rod 2 is inserted. The through hole 36 extends along the extension direction D1. The pushing member 8 includes a base 32 and a head 34 located on one side of the base 32 in the extension direction D1. The head 34 extends further outward in the radial direction D2 than the base 32. A tip surface 38 of the base 32 on the other side in the extension direction D1 is inclined so as to approach the piston 102 as it moves inward in the radial direction D2. The tip surface 38 of the base 32 abuts against the receiving surface 26. The tip surface 38 of the base 32 and the receiving surface 26 are flush with each other. With this configuration, by moving the pushing member 8 toward the other side in the extending direction D1, the tip surface 38 of the base 32 presses the receiving surface 26, and the movable piece 6 moves inward in the radial direction D2. Furthermore, by moving the movable piece 6 inward in the radial direction D2, the first abutment surface 22 of the movable piece 6 presses the first tip surface 12 of the first rod 2, and the first rod 2 moves toward one side in the extending direction D1. As a result, the volume of the combustion chamber 101 decreases, and the compression ratio of the engine 100 changes. Hereinafter, the amount of movement of the first rod 2 in the extending direction D1 by the movable piece 6 when the pushing member 8 makes one rotation is referred to as a second movement amount X2.

[0022] The drive mechanism 9 is not particularly limited as long as it is configured to move the pushing member 8 to the other side in the extension direction D1. In the first embodiment, as shown in Fig. 1, the inner wall surface 40 of the wall portion 20 on the inside in the radial direction D2 has a third helical zigzag shape 84 (described later), and the outer surface 42 of the pushing member 8 on the outside in the radial direction D2 has a fourth helical zigzag shape 90 (described later). Therefore, the drive mechanism 9 according to the first embodiment applies a rotational force Fr to the pushing member 8 to rotate it, thereby moving the pushing member 8 to the other side in the extension direction D1.

[0023] FIG. 3 is a diagram schematically illustrating an example of the configuration of the drive mechanism 9 according to the first embodiment, in which the pushing member 8 is viewed from one side in the extension direction D1. In the configuration illustrated in FIG. 3, the drive mechanism 9 includes a rod-shaped rack 44, a pushing / pulling device 46 that can push and pull the rack 44 along the axial direction D4 of the rack 44, a large cylinder 48 attached to the rack 44, and a small cylinder 50 that has a smaller diameter than the large cylinder 48 and is configured to be pulled out from an end face 49 of the large cylinder 48 opposite the end face on the rack side. The tip of the small cylinder 50 is connected to the head 34 of the pushing member 8. With this configuration, for example, by pulling the rack 44 toward the pushing / pulling device 46, the large cylinder 48 moves to one side in the axial direction D4 (arrow h1). Then, the small cylinder 50 also moves along with the movement of the large cylinder 48, and a rotational force Fr is applied to the head 34 connected to the tip of the small cylinder 50, causing it to rotate (arrow h2). For the sake of explanation, in Fig. 3, the large cylinder 48 after movement is denoted by the reference symbol 48x, and the small cylinder 50 after movement is denoted by the reference symbol 50x. Furthermore, according to the configuration illustrated in Fig. 3, the small cylinder 50 is configured to be retractable from the large cylinder 48 (a so-called telescopic mechanism is applied), so even if the second rod 4 (connecting rod) moves in the vertical direction on the page of Fig. 3 depending on the operation of the engine 100, causing the distance between the rack 44 and the second rod 4 to fluctuate, the fluctuation can be absorbed by the retraction of the small cylinder 50.

[0024] FIG. 4 is a perspective view schematically illustrating another example of the configuration of the drive mechanism 9 according to the first embodiment. In the configuration illustrated in FIG. 4, the drive mechanism 9 includes a first bevel gear 52 provided at one end of the pushing member 8 on one side in the extension direction D1, a second bevel gear 54 configured to be able to mesh with the first bevel gear 52, a rod-shaped support portion 56 that supports the second bevel gear 54, and a transmission portion 60 that transmits a rotational force to the rod-shaped support portion 56 via a clutch 58. In the configuration illustrated in FIG. 4, the head portion 34 of the pushing member 8 is the first bevel gear 52. The clutch 58 is configured to transmit the rotational force of the transmission portion 60 to the support portion 56 by, for example, frictional force generated between two plates 58a and 58b. The two plates 58a and 58b are configured to be able to be coupled to each other at any timing, and are coupled to each other, for example, when the second rod 4 (connecting rod) approaches the combustion chamber 101 so that the distance therebetween is shorter than a predetermined distance. The transmission unit 60 is provided outside the engine 100. The transmission unit 60 has a handle 62 for generating a rotational force. With this configuration, by operating the handle 62, the rotational force is transmitted to the support unit 56. When the rotational force is transmitted to the support unit 56, a rotational force Fr is applied to the second bevel gear 54 (head 34) meshed with the first bevel gear 52, causing it to rotate.

[0025] The resistance force applying mechanism 10 applies to the first rod 2 a resistance force F2 that resists a moving force F1 that moves the first rod 2 to one side (toward the piston 102) in the extending direction D1 of the first rod 2.

[0026] A specific configuration of the resistance force applying mechanism 10 according to the first embodiment will be described with reference to FIG. 5. FIG. 5 is a diagram illustrating the configuration of the resistance force applying mechanism 10 according to the first embodiment. As illustrated in FIG. 5, in the first embodiment, the resistance force applying mechanism 10 includes a first zigzag spiral shape 70 in which first peaks 66 and first valleys 68 are alternately arranged on the outer circumferential surface 64 of the first rod 2, and a second zigzag spiral shape 78 in which second peaks 74 that engage with the first valleys 68 and second valleys 76 that engage with the first peaks 66 are alternately arranged on an inner surface 72 that faces the through hole 36 of the pushing member 8 and is on the inside in the radial direction D2. The first zigzag shape 70 is threadedly engaged with the second zigzag shape 78, and the first rod 2 moves along the extension direction D1 as the pushing member 8 rotates. In the following description, the amount of movement of the first rod 2 in the extension direction D1 due to the first zigzag shape 70 and the second zigzag shape 78 when the pushing member 81 rotates is referred to as a first movement amount X1.

[0027] In the embodiment illustrated in FIG. 5 , a virtual first straight line L1 is defined as a line passing through one end of the first zigzag shape 70 on one side in the extension direction D1 and the other end of the first zigzag shape 70 on the other side in the extension direction D1. The first peaks 66 protrude outward in the radial direction D2 from the virtual first straight line L1. The first valleys 68 are recessed inward in the radial direction D2 from the virtual first straight line L1. Similarly, a virtual second straight line L2 is defined as a line passing through one end of the second zigzag shape 78 on one side in the extension direction D1 and the other end of the second zigzag shape 78 on the other side in the extension direction D1. The second peaks 74 protrude inward in the radial direction D2 from the virtual second straight line L2. The second valleys 76 are recessed outward in the radial direction D2 from the virtual second straight line L2.

[0028] In the embodiment illustrated in FIG. 5 , the vertex 66a of the first mountain portion 66, which is located at the outermost position in the radial direction D2, is located more inward in the radial direction D2 than the second straight line L2. The vertex 66a of the first mountain portion 66 is located more outward in the radial direction D2 than the vertex 74a of the second mountain portion 74, which is located at the innermost position in the radial direction D2. The vertex 74a of the second mountain portion 74 is located more outward in the radial direction D2 than the first straight line L1. Hereinafter, the distance from the vertex 66a of the first mountain portion 66 to the vertex 67a of the first mountain portion 67 adjacent to this first mountain portion 66 is referred to as the pitch pi1 of the first zigzag shape 70. The distance from the vertex 74a of the second mountain portion 74 to the vertex 75a of the second mountain portion 75 adjacent to this second mountain portion 74 is referred to as the pitch pi2 of the second zigzag shape 78.

[0029] The compression ratio changing device 1 according to the first embodiment includes a third zigzag shape 84 and a fourth zigzag shape 90 for rotating the pushing member 8 and moving it to the other side in the extension direction D1. FIG. 6 is a diagram illustrating the third zigzag shape 84 and the fourth zigzag shape 90 according to the first embodiment. In the first embodiment, as illustrated in FIG. 6 , the inner wall surface 40 of the wall portion 20 has a spiral third zigzag shape 84 in which third peaks 80 and third valleys 82 are alternately arranged. The outer surface 42 of the pushing member 8 has a spiral fourth zigzag shape 90 in which fourth peaks 86 that engage with the third valleys 82 and fourth valleys 88 that engage with the third peaks 80 are alternately arranged. The fourth zigzag shape 90 is threadedly engaged with the third zigzag shape 84, and the pushing member 8 is moved along the extension direction D1 by a rotational force Fr applied by the drive mechanism 9.

[0030] In the first embodiment, the pitch pi1 of the first zigzag shape 70, the pitch pi2 of the second zigzag shape 78, the inclination angle θ1 of the first tip surface 12, and the inclination angle θ2 of the first abutment surface 22 are each configured (adjusted) so that the first movement amount X1 and the second movement amount X2 are equal to each other.

[0031] In the first embodiment, a first play 91 formed between the first zigzag shape 70 and the second zigzag shape 78 is larger than a second play 93 formed between the third zigzag shape 84 and the fourth zigzag shape 90. An example of how to measure the first play 91 and the second play 93 will be described. The first play 91 is the length of an imaginary vertical line (shown by a dotted line in FIG. 5) extending from the first peak 66 to the second peak 74. This vertical line is perpendicular to the plane of the first peak 66. The second play 93 is the length of an imaginary vertical line (shown by a dotted line in FIG. 6) extending from the fourth peak 86 to the third peak 80.

[0032] (Actions and Effects) The operation and effect of the compression ratio change device 1A according to the first embodiment will be described. While the engine 100 is operating, the pressure (internal cylinder pressure) in the combustion chamber 101 is high, so the first rod 2 is maintained in contact with the movable piece 6. When the compression ratio change device 1A is activated, the movable piece 6 presses the first rod 2 to one side in the extension direction D1, so that the first rod 2 moves in the extension direction D1 while maintaining its contact with the movable piece 6. However, for example, if an unintended decrease in the internal cylinder pressure occurs or if the frictional force between the piston 102 and the cylinder liner 104 increases, the first rod 2 may separate from the movable piece 6. If the first rod 2 separates from the movable piece 6, a collision between the first rod 2 and the movable piece 6 occurs, damaging at least one of the first rod 2 and the movable piece 6.

[0033] According to the first embodiment, even if the first rod 2 attempts to move to one side in the extension direction D1 so as to move away from the movable piece 6, the first zigzag shape 70 of the first rod 2 interferes with the second zigzag shape 78 of the pushing member 8, and a resistance force F2 is applied to the first rod 2. This prevents the first rod 2 from moving away from the movable piece 6. This prevents the first rod 2 from colliding with the movable piece 6, thereby preventing damage to the first rod 2 or the movable piece 6.

[0034] According to the first embodiment, the wall portion 20 has the third zigzag shape 84, and the pushing member 8 has the fourth zigzag shape 90, thereby providing a pushing member 8 that moves the movable piece 6 in the radial direction D2 when rotated. According to the first embodiment, the pitch pi1 of the first zigzag shape 70, the pitch pi2 of the second zigzag shape 78, the inclination angle θ1 of the first tip surface 12, and the inclination angle θ2 of the first abutment surface 22 are all adjusted so that the first movement amount X1 and the second movement amount X2 are equal to each other. Therefore, when changing the compression ratio of the engine 100, damage to the first zigzag shape 70 of the first rod 2 or the second zigzag shape 78 of the pushing member 8 caused by the difference between the first movement amount X1 and the second movement amount X2 can be suppressed. If the first movement amount X1 is greater than the second movement amount X2, there is a risk that the first rod 2 will move away from the movable piece 6. If the first movement amount X1 is smaller than the second movement amount X2, the load acting on each of the first zigzag shape 70 and the second zigzag shape 78 increases, and there is a risk that the first zigzag shape 70 or the second zigzag shape 78 may be damaged.

[0035] The first rod 2 is directly subjected to the in-cylinder pressure via the piston 102. Therefore, there is a risk that the first zigzag shape 70 or the second zigzag shape 78 may be damaged by the in-cylinder pressure. To address this risk, according to the first embodiment, the first play 91 is formed, which allows the in-cylinder pressure to be received by the movable piece 6, thereby suppressing damage to the first zigzag shape 70 or the second zigzag shape 78. Furthermore, by making the first play 91 larger than the second play 93, it is possible to increase the range of allowable manufacturing errors and prevent the first zigzag shape 70 and the second zigzag shape 78 from interfering with each other more than necessary during operation of the engine 100.

[0036] In some embodiments, the engine 100 is a horizontally opposed engine or an opposed-piston engine in which two pistons 102 are arranged horizontally opposite each other in one cylinder. In a horizontally opposed engine or an opposed-piston engine, the gravity of the piston 102 or the first rod 2 (piston rod) does not help move the first rod 2 to the other side (toward the movable piece 6) in the extension direction D1. Without this help, the first rod 2 is more likely to separate from the movable piece 6. For this reason, it is very advantageous to provide the compression ratio changing device 1 according to the present disclosure in a horizontally opposed engine or an opposed-piston engine. Note that the engine 100 may be an engine other than a horizontally opposed engine, such as a V-type engine or a four-stroke engine.

[0037] Second Embodiment A compression ratio changing device 1B(1) according to a second embodiment of the present disclosure will be described. The compression ratio changing device 1B according to the second embodiment differs from the first embodiment in the configuration of the resistance force applying mechanism 10. In the second embodiment, the same components as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0038] (composition) FIG. 7 is a diagram schematically illustrating the configuration of a compression ratio changing device 1B according to a second embodiment. The resistance force applying mechanism 10B (10) will be described after explaining the drive mechanism 9 according to the second embodiment. The drive mechanism 9 according to the second embodiment pulls the pushing member 8 toward the other side in the extension direction D1, thereby moving the pushing member 8 toward the other side in the extension direction D1. In the embodiment illustrated in FIG. 7, the drive mechanism 9 includes a spring 92 for applying a biasing force to the pushing member 8 toward one side in the extension direction D1, and a solenoid coil 94 built into the wall portion 20. In the embodiment illustrated in FIG. 7, one end 92a of the spring 92 on one side in the extension direction D1 is connected to the surface 35 of the head portion 34 on the other side in the extension direction D1, and the other end 92b on the other side in the extension direction D1 is connected to the surface 21 of the wall portion 20 on one side in the extension direction D1. When the solenoid coil 94 is energized and generates an electromagnetic force, it pulls the pushing member 8 to the other side in the extension direction D1 against the spring 92. In the compression ratio changing device 1B according to the second embodiment, energizing the solenoid coil 94 moves the pushing member 8 to the other side in the extension direction D1, thereby changing the compression ratio of the engine 100.

[0039] A resistance force applying mechanism 10B (10) according to the second embodiment will be described. As illustrated in Fig. 7, the resistance force applying mechanism 10B includes a coil 96 provided on the pushing member 8 and positioned outside the through-hole 36 in the radial direction D2, and a magnet 98 provided on the first rod 2 and positioned on the other side of the coil 96 in the extension direction D1 (the side opposite the piston 102) and inside the coil 96 in the radial direction D2. In the embodiment illustrated in Fig. 7, the coil 96 is built into the head 34. The magnet 98 is built into the first rod 2.

[0040] (Actions and Effects) The operation and effect of the compression ratio change device 1B according to the second embodiment will be described. According to the second embodiment, even if the first rod 2 attempts to move to one side in the extension direction D1 so as to move away from the movable piece 6, a magnetic field that prevents the magnet 98 from approaching the coil 96 is generated from the coil 96, and a resistance force F2 is applied to the first rod 2. This makes it possible to prevent the first rod 2 from moving away from the movable piece 6.

[0041] <Third embodiment> A compression ratio changing device 1C(1) according to a third embodiment of the present disclosure will be described. The compression ratio changing device 1C according to the third embodiment differs from the first and second embodiments in the configuration of the resistance force applying mechanism 10. In the third embodiment, the same components as those in the first or second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0042] (composition) 8 is a diagram schematically illustrating the configuration of a compression ratio changing device 1C according to the third embodiment. As illustrated in FIG. 8, the resistance force applying mechanism 10C(10) includes a flange portion 120, a box member 122, a first line 124, and a second line 126.

[0043] The flange portion 120 is provided on the first rod 2 and is located closer to the piston 102 than the end face 37 on one side (piston side) in the extending direction D1 of the pushing member 8. In the embodiment illustrated in Fig. 8, the flange portion 120 is integrally formed with the first rod 2. The flange portion 120 extends outward from the first rod 2 in the radial direction D2.

[0044] The box member 122 surrounds the flange portion 120 and an end portion 39 having an end face 37 of the pushing member 8. The internal space of the box member 122 is divided by the flange portion 120 into a first space 128 and a second space 130. The first space 128 faces the end face 37 of the pushing member 8. The second space 130 is located on the opposite side of the flange portion 120 from the first space 128 in the extension direction D1. In the embodiment illustrated in FIG. 8 , the box member 122 houses the head portion 34. The box member 122 is supported by the wall portion 20. Although not shown, in some embodiments, the compression ratio changing device 1C further includes a seal member interposed between the inner circumferential surface of the box member 122 and the outer circumferential surface of the flange portion 120 in the radial direction D2.

[0045] The first line 124 communicates with the first space 128, and has a flow path formed therein through which the first fluid 132 flows. The first line 124 is configured to allow the first fluid 132 to flow into the box member 122 or to allow the first fluid 132 to flow out from the box member 122. In the embodiment illustrated in FIG. 8, the compression ratio changing device 1C further includes a first valve 136 provided in the first line 124. The first fluid 132 is not particularly limited and may be, for example, oil.

[0046] The second line 126 is in communication with the second space 130, and has a flow path formed therein through which the second fluid 134 flows. The second line 126 is configured to allow the second fluid 134 to flow into the box member 122 or to allow the second fluid 134 to flow out from the box member 122. In the embodiment illustrated in FIG. 8 , the compression ratio changing device 1C further includes a second valve 138 provided in the second line 126. The second fluid 134 is not particularly limited and may be, for example, oil. The second fluid 134 may be the same fluid as the first fluid 132, or may be a fluid different from the first fluid 132.

[0047] The drive mechanism 9 according to the third embodiment presses the pushing member 8 toward the other side in the extension direction D1, thereby moving the pushing member 8 toward the other side in the extension direction D1. In the embodiment illustrated in FIG. 8 , the drive mechanism 9 includes a flange portion 120, a box member 122, and a first line 124. When a first fluid 132 is introduced from the first line 124 into the first space 128 to increase the pressure in the first space 128, the pushing member 8 is pressed toward the other side in the extension direction D1 by the first fluid 132. The compression ratio change device 1C according to the third embodiment is configured to change the compression ratio of the engine 100 by introducing the first fluid 132 into the first space 128, thereby moving the pushing member 8 toward the other side in the extension direction D1. When changing the compression ratio of the engine 100, both the first valve 136 and the second valve 138 are opened.

[0048] (Actions and Effects) According to the third embodiment, even if the first rod 2 attempts to move to one side in the extension direction D1 so as to move away from the movable piece 6, a resistance force F2 is applied to the first rod 2 by maintaining a constant pressure in the second space 130 into which the second fluid 134 flows. This makes it possible to prevent the first rod 2 from moving away from the movable piece 6. Furthermore, since the compression ratio of the engine 100 can be changed by the flow of the first fluid 132 into the first space 128, it is not necessary to provide a mechanism for changing the compression ratio of the engine 100 separately from the first space 128 and the first fluid 132.

[0049] The contents described in each of the above embodiments can be understood, for example, as follows.

[0050] [1] A compression ratio change device (1) according to the present disclosure is a compression ratio change device for changing the compression ratio of an engine (100), a first rod (2) extending from a piston (102) of the engine, the first rod (2) having a first tip surface (12) inclined so as to approach the piston as it moves outward in a radial direction (D2); a second rod (4) extending from the crankshaft (110) of the engine; a movable piece (6) including a first contact surface (22) that contacts the first tip surface of the first rod and is inclined so as to approach the piston as it moves outward in the radial direction, and a second contact surface (24) that contacts a second tip surface (16) of the second rod; a pushing member (8) configured to move the first rod in an extending direction (D1) of the first rod by moving the movable piece in the radial direction while bringing the first contact surface into contact with the first tip end surface of the first rod and bringing the second contact surface into contact with the second tip end surface of the second rod; and a resistance force applying mechanism (10) that applies to the first rod a resistance force (F2) that resists a moving force (F1) that moves the first rod toward the piston in the extension direction.

[0051] According to the configuration described in [1] above, even if an unintended decrease in cylinder pressure or an increase in friction between the piston and the cylinder liner occurs, a resistance force that resists the force that moves the first rod toward the piston in the extension direction is applied to the first rod, thereby preventing the first rod from moving away from the movable piece. This prevents a collision between the first rod and the movable piece and prevents damage to the first rod or the movable piece.

[0052] [2] In some embodiments, in the configuration described in [1] above, The pushing member extends along the extension direction and has a through hole (36) through which the first rod is inserted, The resistance force applying mechanism includes: a spiral first zigzag shape (70) in which first peaks (66) and first valleys (68) are alternately arranged on the outer peripheral surface (64) of the first rod; and a second zigzag spiral shape (78) on the radially inner inner surface (72) facing the through hole of the pushing member, in which second peaks (74) that engage with the first valleys and second peaks (76) that engage with the first valleys are alternately arranged.

[0053] According to the configuration described in [2] above, even if the first rod attempts to move toward the piston in the extension direction so as to move away from the movable piece, the first zigzag shape of the first rod interferes with the second zigzag shape of the pushing member, applying resistance to the first rod, thereby preventing the first rod from moving away from the movable piece.

[0054] [3] In some embodiments, in the configuration described in [2] above, the second rod includes a wall portion (20) extending from an outer edge portion (18) of the second tip surface of the second rod toward the piston and covering the pushing member from the outside in the radial direction, an inner wall surface (40) on the inner side in the radial direction of the wall portion has a third zigzag shape (84) in a spiral shape in which third peaks (80) and third valleys (82) are alternately arranged; an outer surface (42) on the outside in the radial direction of the pushing member has a fourth zigzag shape (90) in a spiral shape in which fourth peaks (86) that engage with the third valleys and fourth valleys (88) that engage with the third peaks are alternately arranged; The pitch (pi1) of the first zigzag shape, the pitch (pi2) of the second zigzag shape, the inclination angle (θ1) of the first tip surface, and the inclination angle (θ2) of the first abutment surface are configured so that the amount of movement (X1) of the first rod in the extension direction due to the first zigzag shape and the second zigzag shape and the amount of movement (X2) of the first rod in the extension direction due to the movable piece are equal to each other.

[0055] According to the configuration described in [3] above, by providing a pushing member in which the wall portion has a third zigzag shape and the pushing member has a fourth zigzag shape, it is possible to provide a pushing member that moves the movable piece radially when rotated. Furthermore, when changing the compression ratio of the engine, it is possible to suppress damage to the first zigzag shape of the first rod or the second zigzag shape of the pushing member caused by the difference between the amount of movement of the first rod in the extension direction due to the first zigzag shape and the second zigzag shape and the amount of movement of the first rod in the extension direction due to the movable piece.

[0056] [4] In some embodiments, in the configuration described in [3] above, A play (91) formed between the first zigzag shape and the second zigzag shape is larger than a play (93) formed between the third zigzag shape and the fourth zigzag shape.

[0057] The first rod is directly subjected to the in-cylinder pressure via the piston. Therefore, there is a risk that the first zigzag shape or the second zigzag shape may be damaged by the in-cylinder pressure. To address this risk, the configuration described in [4] above provides clearance between the first zigzag shape and the second zigzag shape, allowing the in-cylinder pressure to be received by the movable piece, thereby suppressing damage to the first zigzag shape or the second zigzag shape. Furthermore, by making the clearance between the first zigzag shape and the second zigzag shape larger than the clearance between the third zigzag shape and the fourth zigzag shape, it is possible to increase the range of allowable manufacturing errors and prevent unnecessary interference between the first zigzag shape and the second zigzag shape during engine operation.

[0058] [5] In some embodiments, in the configuration described in [1] above, The pushing member extends along the extension direction and has a through hole (36) through which the first rod is inserted, The resistance force applying mechanism includes: a coil (96) provided on the pushing member and positioned radially outward of the through hole; a magnet (98) provided on the first rod at a position opposite to the piston side in the extension direction relative to the coil and more inward in the radial direction relative to the coil.

[0059] According to the configuration described in [5] above, even if the first rod attempts to move toward the piston in the extension direction so as to move away from the movable piece, a magnetic field that prevents the magnet from approaching the coil is generated from the coil, and a resistance force is applied to the first rod, thereby preventing the first rod from moving away from the movable piece.

[0060] [6] In some embodiments, in the configuration described in [1] above, a spring (92) for applying a biasing force to the pushing member toward one side of the extension direction; The engine further includes a solenoid coil (94) that is built into the second rod and is configured to adjust the compression ratio of the engine by an electromagnetic force that resists the biasing force when energized.

[0061] According to the configuration described in [6] above, it is possible to provide a compression ratio changing device that can change the compression ratio of an engine by the electromagnetic force generated by the solenoid coil.

[0062] [7] In some embodiments, in the configuration described in [1] above, The resistance force applying mechanism includes a flange portion (120) provided on the first rod and positioned closer to the piston than an end face (37) of the pushing member on the piston side in the extension direction; a box member (122) that surrounds the flange portion and the end portion (39) of the pushing member having the end face, the box member having an internal space that is divided by the flange portion into a first space (128) facing the end face of the pushing member and a second space (130) located on the opposite side of the first space with the flange portion in between; a first line (124) communicating with the first space for introducing a first fluid (132) into the box member or discharging the first fluid from the box member; and a second line (126) communicating with the second space for introducing a second fluid (134) into the box member or discharging the second fluid from the box member.

[0063] According to the configuration described in [7] above, even if the first rod attempts to move toward the piston in the extension direction so as to separate from the movable piece, a resistance force is applied to the first rod by maintaining a constant pressure in the second space into which the second fluid flows, thereby preventing the first rod from separating from the movable piece.

[0064] [8] The engine (100) according to the present disclosure includes: The compression ratio changing device (1) according to any one of the above [1] to [7] is provided.

[0065] According to the configuration described in [8] above, it is possible to provide an engine that can suppress damage to the first rod or the movable piece. [Explanation of symbols]

[0066] 1 Compression ratio change device 1A Compression ratio changing device (first embodiment) 1B Compression ratio changing device (second embodiment) 1C Compression ratio changing device (third embodiment) 2. First Rod 4 Second Rod 4a Proximal end 6 Movable piece 6A First moving piece 6B Second moving piece 6C Third moving piece 6D Fourth moving piece 8 Push-in member 9 Drive mechanism 10 Resistance Mechanism 10A Resistance force applying mechanism (first embodiment) 10B Resistance force applying mechanism (second embodiment) 10C Resistance force applying mechanism (third embodiment) 12 1st tip surface 12a outer edge 16 2nd tip surface 18 outer edge 20 Wall 22 First contact surface 24 Second contact surface 26 Receiving surface 28 Inner 30 Exterior 32 Base 34 Head 36 Through hole 37 End face of pushing member 38 Tip surface of pushing member 39 End 40 Inner wall surface of wall 42 Outer surface of the pushing member 44 racks 46 Push / pull device 48 Large tube 50 small tube 52 First bevel gear 54 Second bevel gear 56 Support part 58 Clutch 60 Transmission Unit 62 Handle 64 outer surface of first rod 66 First Mountain Section 68 First Valley 70 First zigzag shape 72 Inner surface of the pushing member 74 Second Mountain 76 Second Valley 78 Second zigzag shape 80 Third Mountain 82 Third Valley 84 Third Zigzag Shape 86 4th Mountain Section 88 4th Valley 90 4th Zigzag Shape 91 First Play 92 Spring 93 Second Play 94 Solenoid coil 96 Coil 98 Magnet 100 Engine 101 Combustion chamber 102 Piston 104 Cylinder liner 110 crankshaft 120 flange 122 Box material 124 First Line 126 Second Line 128 1st space 130 Second space 132 First Fluid 134 Second Fluid 136 First Valve 138 Second Valve D1 Extending direction D2 radial direction D3 Circumferential direction D4 Axial direction F1 Movement F2 resistance Fr rotational force L1 1st straight line L2 2nd straight line La Virtual Line O center line Oc axial direction P1 center position X1 1st travel amount X2 2nd travel amount pi1 Pitch of the first zigzag shape pi2 Pitch of the second zigzag shape

Claims

1. A compression ratio changing device for changing the compression ratio of an engine, a first rod extending from a piston of the engine, the first rod having a first tip surface inclined so as to approach the piston as it extends radially outward; a second rod extending from the crankshaft of the engine; a movable piece including a first contact surface that contacts the first tip end surface of the first rod and is inclined so as to approach the piston as it extends radially outward, and a second contact surface that contacts a second tip end surface of the second rod; a pushing member configured to move the first rod in the extending direction of the first rod by moving the movable piece in the radial direction while bringing the first contact surface into contact with the first tip end surface of the first rod and bringing the second contact surface into contact with the second tip end surface of the second rod; a resistance force applying mechanism that applies a resistance force to the first rod that resists a moving force that moves the first rod toward the piston in the extension direction, Compression ratio change device.

2. the pushing member extends along the extension direction and has a through hole through which the first rod is inserted, The resistance force applying mechanism includes: a first zigzag spiral shape in which first peaks and first valleys are alternately arranged on an outer circumferential surface of the first rod; a second zigzag spiral shape in which second peaks engaged with the first valleys and second peaks engaged with the first valleys are alternately arranged on an inner surface of the pushing member facing the through hole in the radial direction, The compression ratio changing device according to claim 1 .

3. the second rod includes a wall portion that extends from an outer edge portion of the second tip surface of the second rod toward the piston and covers the pushing member from the outside in the radial direction, an inner wall surface of the wall portion on the inside in the radial direction has a third zigzag spiral shape in which third peaks and third valleys are alternately arranged, an outer surface on the outside in the radial direction of the pushing member has a fourth zigzag spiral shape in which fourth peak portions that engage with the third valley portions and fourth valley portions that engage with the third peak portions are alternately arranged, the pitch of the first zigzag shape, the pitch of the second zigzag shape, the inclination angle of the first tip end surface, and the inclination angle of the first abutment surface are configured so that the movement amount of the first rod in the extension direction due to the first zigzag shape and the second zigzag shape and the movement amount of the first rod in the extension direction due to the movable piece are equal to each other. The compression ratio changing device according to claim 2.

4. a play formed between the first zigzag shape and the second zigzag shape is larger than a play formed between the third zigzag shape and the fourth zigzag shape; The compression ratio changing device according to claim 3.

5. the pushing member extends along the extension direction and has a through hole through which the first rod is inserted, The resistance force applying mechanism includes: a coil provided on the pushing member and positioned radially outward of the through hole; a magnet provided on the first rod, the magnet being positioned on the opposite side of the coil from the piston in the extension direction and on the inner side of the coil in the radial direction, The compression ratio changing device according to claim 1 .

6. a spring for applying a biasing force to the pushing member toward one side of the extension direction; a solenoid coil that is built into the second rod and that, when energized, adjusts the compression ratio of the engine by an electromagnetic force that resists the biasing force, The compression ratio changing device according to claim 1 .

7. the resistance force applying mechanism includes a flange portion provided on the first rod and positioned closer to the piston than an end face of the pushing member on the piston side in the extension direction; a box member that encloses the flange portion and the end portion having the end face of the pushing member, the box member having an internal space that is divided by the flange portion into a first space facing the end face of the pushing member and a second space located on the opposite side of the flange portion from the first space; a first line communicating with the first space for allowing a first fluid to flow into the box member or for allowing the first fluid to flow out of the box member; a second line communicating with the second space for introducing a second fluid into the box member or for discharging the second fluid from the box member; The compression ratio changing device according to claim 1 .

8. A compression ratio changing device according to any one of claims 1 to 7, engine.

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