CN110284966B

CN110284966B - Lower connecting rod and engine with same

Info

Publication number: CN110284966B
Application number: CN201910580253.3A
Authority: CN
Inventors: 刘涛; 刘俊杰; 林文; 钟德华; 渠娜; 张树旻; 杨乐; 姜志永; 尹吉; 刘君宇; 董高峰; 苏旭朝; 王文远
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2019-06-28
Filing date: 2019-06-28
Publication date: 2021-04-20
Anticipated expiration: 2039-06-28
Also published as: CN110284966A

Abstract

The invention discloses a lower connecting rod and an engine with the same. Be provided with on this lower connecting rod with bent axle complex centre bore, lower connecting rod includes: the connecting rod part is connected with the control connecting rod part, at least one connecting point is a rotating connecting point, and the rotating axis of the rotating connecting point is parallel to the axis of the central hole. According to the lower connecting rod, the upper connecting rod part and the control connecting rod part can rotate relatively around the rotating connecting point, so that the assembling process of the lower connecting rod and the crankshaft is simplified, the assembling difficulty is reduced, and the upper connecting rod part and the control connecting rod part are rotatably connected through the hinge pin at the rotating connecting point, so that the stress of the lower connecting rod is favorably improved.

Description

Lower connecting rod and engine with same

Technical Field

The invention relates to the field of automobiles, in particular to a lower connecting rod and an engine with the same.

Background

The compression ratio of the engine is the ratio of the volume of the cylinder when the piston moves to the bottom dead center to the volume of the combustion chamber when the piston moves to the top dead center. Most of the existing engines are fixed compression ratio engines, and have low fuel combustion efficiency, poor economical efficiency and high emission. With the development of the variable compression ratio technology, the engine starts to increase a compression ratio adjusting mechanism, changes the volume of a combustion chamber by changing the top dead center position of a piston and the like, thereby changing the compression ratio to meet different engine load requirements and enable the engine to work in an optimal working area all the time, thereby improving the dynamic property, reducing the oil consumption, reducing the emission and well solving the contradiction between the dynamic property and the economical efficiency as well as the emission.

At present, a typical structure for changing the top dead center position of an engine piston is a multi-connecting rod mechanism, a lower connecting rod of the multi-connecting rod mechanism is connected with a connecting rod neck of a crankshaft, but when the engine works, the lower connecting rod is stressed maximally due to inertia force, the structural design requirement is strict, and the assembly is complex.

Disclosure of Invention

In view of the above, the present invention is directed to a lower connecting rod to optimize an assembling process of the lower connecting rod.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a lower connecting rod is provided with a center hole matched with a crankshaft, and comprises: the connecting rod part is connected with the control connecting rod part, at least one connecting point is a rotating connecting point, and the rotating axis of the rotating connecting point is parallel to the axis of the central hole.

According to some embodiments of the invention, at the rotational connection point, the upper link part and the control link part are rotationally connected by a hinge pin.

Furthermore, one of the upper connecting rod part and the control connecting rod part is provided with a hinge hole seat, the other one is provided with a connecting arm, and the hinge hole seat and the connecting arm are provided with hinge pin holes for mounting the hinge pins.

Optionally, the connecting arm includes a first connecting arm and a second connecting arm that are disposed along the hinge pin axis direction at intervals, and the reaming base is sandwiched between the first connecting arm and the second connecting arm.

Optionally, the reamer seat is a single reamer seat.

Optionally, the hinge hole seat includes a first hinge hole seat and a second hinge hole seat arranged at intervals along the axis direction of the hinge pin, and the hinge pin hole is arranged on the first hinge hole seat and the second hinge hole seat.

According to some embodiments of the present invention, a parting surface is formed between the upper connecting rod portion and the control connecting rod portion, an upper central half hole is formed on the upper connecting rod portion, a lower central half hole is formed on the control connecting rod portion, the upper central half hole and the lower central half hole enclose the central hole, and a plane of the parting surface is arranged to pass through an axis of the central hole.

Further, the axis of the hinge pin hole is located in the plane of the parting plane.

According to some embodiments of the invention, the upper link portion is provided with an upper link pin hole, the control link portion is provided with a control link pin hole, and the parting plane includes, as viewed in an axial direction of the center hole of the lower link: the hinge pin is located at the upper section parting surface.

According to some embodiments of the invention, one of the connection points of the upper link portion and the control link portion is a threaded connection point.

Furthermore, an upper connecting rod pin hole is formed in the upper connecting rod portion, a control connecting rod pin hole is formed in the control connecting rod portion, the upper connecting rod portion and the control connecting rod portion are surrounded to form the central hole, the rotating connection point is located on one side, close to the upper connecting rod pin hole, of the central hole, and the screw connection point is located on one side, close to the control connecting rod pin hole, of the central hole.

Optionally, a bolt is arranged at the bolt joint, and a central axis of the bolt is perpendicular to a central axis of the hinge pin.

According to some embodiments of the invention, one of the hinge pin hole in the connecting arm and the hinge pin hole in the hinge hole seat is an interference fit when engaged with the hinge pin, and the other is a clearance fit when engaged with the hinge pin.

According to some embodiments of the invention, the upper link portion and the control link portion are connected by two connection points, and both of the connection points are rotational connection points.

Compared with the prior art, the lower connecting rod has the following advantages:

(1) according to the lower connecting rod, the upper connecting rod part and the control connecting rod part can rotate relatively around the rotating connecting point, so that the assembling process of the lower connecting rod and the crankshaft is simplified, and the assembling difficulty is reduced.

(2) According to the lower connecting rod, at least one connecting point of the upper connecting rod part and the control connecting rod part is a rotating connecting point, and the upper connecting rod part and the control connecting rod part are rotatably connected through the hinge pin at the rotating connecting point, so that the stress of the lower connecting rod is favorably improved.

Another object of the invention is to propose an engine comprising: a piston adapted to move within a cylinder of the engine; a crankshaft, a main journal of which is rotatably provided on a cylinder block of the engine; the lower connecting rod is sleeved on the connecting rod neck of the crankshaft; an upper connecting rod connected between the piston and the lower connecting rod; a compression ratio adjustment mechanism for adjusting a position of the piston within the cylinder, the compression ratio adjustment mechanism comprising: and the control connecting rod is hinged with the lower connecting rod.

Compared with the prior art, the engine has the following advantages:

(1) the engine has the advantages that the number of parts of the compression ratio adjusting mechanism is small, so that the purpose of changing the compression ratio of the engine can be achieved, the assembly process of the engine is favorably reduced, the number of parts is small, and the working reliability of the compression ratio adjusting mechanism is favorably improved.

(2) After the lower connecting rod is adopted, at least one connecting point of the upper connecting rod part and the control connecting rod part is a rotating connecting point, so that the lower connecting rod and the crankshaft are convenient to assemble, and the stress of the lower connecting rod can be improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is an assembled schematic view of a piston, an upper connecting rod, a lower connecting rod, a crankshaft, a compression ratio adjustment mechanism;

FIG. 2 is an assembled view of the piston, upper link, lower link, and compression ratio adjustment mechanism;

FIG. 3 is an exploded view of the upper connecting rod, lower connecting rod, crankshaft, control connecting rod, and bearing shell;

FIG. 4 is a schematic view of the assembly of the upper link, lower link, link neck, control link, and bearing shell;

FIG. 5 is a schematic view of the lower bearing shell and the height of the remainder of the lower bearing shell;

FIG. 6 is an assembled view of the upper link, the control link, and the lower link of the first embodiment;

FIG. 7 is an exploded schematic view of the lower link of the first embodiment;

FIG. 8 is a schematic view of the connection of the hinge socket, the connecting arm and the hinge pin;

FIG. 9 is a force analysis diagram of the upper link, control link, lower link of the first embodiment;

FIG. 10 is a schematic view of a force analysis of the upper link portion and the control link portion using a link bolt connection at both ends;

FIG. 11 is an assembled view of the upper link, the control link, and the lower link of the second embodiment;

FIG. 12 is an exploded schematic view of a lower link of a third embodiment;

FIG. 13 is an assembled view of the lower link of the fourth embodiment;

FIG. 14 is an exploded schematic view of a lower link of the fourth embodiment;

FIG. 15 is an exploded schematic view of a lower link of the fifth embodiment;

FIG. 16 is a cross-sectional view of the upper link portion and the control link portion with one end pivotally connected and the other end bolted using a link bolt;

FIG. 17 is a schematic view of a projection area of the lower link of the first embodiment;

FIG. 18 is a schematic illustration of the projected area interfering with the central aperture;

FIG. 19 is an exploded view of the upper link portion and the control link portion of the lower link of the first embodiment;

FIG. 20 is an exploded view of the upper link portion and the control link portion of the lower link of the fifth embodiment;

FIG. 21 is a schematic view of the relative rotational angles of the upper link portion and the control link portion;

FIG. 22 is a top view of the boss disposed on the upper link portion;

FIG. 23 is an enlarged partial schematic view at M of FIG. 22;

FIG. 24 is a perspective view of the boss provided on the upper link portion;

FIG. 25 is a schematic view of the boss being located on the control link portion with the lower bearing shell having a clearance height;

FIG. 26 is an enlarged partial schematic view at N of FIG. 25;

FIG. 27 is a schematic view of the assembly of the lower connecting rod with the upper and lower bearing shells;

fig. 28 is an exploded view of the lower link and the upper and lower bearing shells.

Description of reference numerals:

the piston 1, the upper connecting rod 2, the crankshaft 4, the main journal 41, the connecting journal 42, the compression ratio adjusting mechanism 7, the control connecting rod 5, the eccentric shaft 6, the drive shaft 61, the eccentric wheel 62, the piston pin a, the connecting pin B, the bearing bush C, the control connecting pin D, the lower connecting rod 3, the upper connecting rod part 31, the upper connecting pin hole 311, the first screw hole 314, the upper center half hole 316, the control connecting rod part 32, the control connecting pin hole 321, the second screw hole 323, the second screw hole 324, the lower center half hole 326, the center hole 33, the connecting rod bolt 35, the boss 37, the hinge hole seat boss 371, the connecting arm boss 372, the reinforcing rib 38, the parting surface 40, the upper section parting surface 401, the lower section 402, the hinge hole seat 51, the first hinge hole seat 511, the second hinge hole seat 512, the connecting arm 52, the first connecting arm 521, the second connecting arm 522, the hinge pin 53, the hinge pin hole 54, the upper bearing bush 81, the lower, The area Q is projected.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention will be described in detail with reference to fig. 1 to 28 in conjunction with the embodiments.

Referring to fig. 1-3, an engine may include: the piston 1, the upper connecting rod 2, the lower connecting rod 3, the crankshaft 4 and the compression ratio adjusting mechanism 7.

Specifically, the lower connecting rod 3 of the embodiment of the invention is suitable for being connected with a crankshaft 4 of an engine in an articulated mode, and the piston 1 can move in a cylinder of the engine, and the piston 1 can move in the cylinder hole of the cylinder in the up-and-down direction of the figures 1-2 in combination with the figures 1-2.

The main journal 41 of the crankshaft 4 is rotatably provided in the cylinder block of the engine, and the connecting journal 42 of the crankshaft 4 is offset from the central axis of the main journal 41. There may be a plurality of connecting journals 42 of the crankshaft 4.

The lower connecting rod 3 is sleeved on one of the connecting rod necks 42, specifically, the lower connecting rod 3 is provided with a central hole 33, the connecting rod neck 42 is positioned in the central hole 33, and the lower connecting rod 3 and the connecting rod neck 42 can rotate mutually. In some embodiments, a journal pin or bushing C may be disposed between the lower link 3 and the journal 42 to reduce wear of the lower link 3 and the journal 42 and extend the component life of the engine.

The upper connecting rod 2 is connected between the piston 1 and the lower connecting rod 3, that is, a first end of the upper connecting rod 2 is connected to the piston 1, and a second end of the upper connecting rod 2 is connected to the lower connecting rod 3. Specifically, the first end of the upper connecting rod 2 is hinged to the piston 1, and the second end of the upper connecting rod 2 is hinged to the lower connecting rod 3, so that the upper connecting rod 2 and the piston 1 can rotate relative to each other, and the upper connecting rod 2 and the lower connecting rod 3 can rotate relative to each other, so that when the lower connecting rod 3 rotates around the connecting rod neck 42 sleeved with the lower connecting rod 3, the upper connecting rod 2 can be driven to move, and then the piston 1 is driven to move up and down.

The compression ratio adjusting mechanism 7 is used for adjusting the position of the piston 1 in the cylinder, so that the position of the piston 1 relative to the cylinder at the top dead center and the bottom dead center is changed, and then the compression ratio is changed. As shown in fig. 1 to 2, the compression ratio adjustment mechanism 7 may include: the eccentric shaft 6 and the control connecting rod 5, the control connecting rod 5 is connected between the lower connecting rod 3 and the eccentric shaft 6, the first end of the control connecting rod 5 is connected with the lower connecting rod 3, and the second end of the control connecting rod 5 is eccentrically connected with the eccentric shaft 6, so that when the eccentric shaft 6 rotates, the power of the eccentric shaft 6 can be transmitted to the lower connecting rod 3 through the control connecting rod 5, and the lower connecting rod 3 rotates around a connecting rod neck 42 sleeved with the lower connecting rod 3.

Specifically, when the eccentric shaft 6 rotates, the control connecting rod 5 is pushed to rotate, the control connecting rod 5 pushes the lower connecting rod 3 to rotate, the lower connecting rod 3 pushes the upper connecting rod 2 to rotate, and the upper connecting rod 2 pushes the piston 1 to move up and down, so that the position of the piston 1 in the cylinder can be adjusted. The piston 1 moves up and down, changing the volume of the combustion chamber and thus the compression ratio. That is, the compression ratio adjustment mechanism 7 may function to change the engine compression ratio. By changing the compression ratio, the requirements of different loads of the engine can be met, and the engine can always work in the optimal working area, so that the dynamic property is improved, the oil consumption is reduced, the emission is reduced, the contradiction between the dynamic property and the economical efficiency and the emission is well solved, and the engine can always work in the optimal oil consumption area.

It should be noted that, in the description of the present invention, the "first end" of the component refers to the upper end of the drawing, and the "second end" refers to the lower end of the drawing, but the words indicating the orientation such as "first end", "second end", "upper", "lower", etc. are only for convenience of description, and should not be construed as limiting the present invention.

In the specific embodiment, the compression ratio adjusting mechanism 7 has fewer parts, so that the purpose of changing the compression ratio of the engine can be achieved, the assembly process of the engine is favorably reduced, and the working reliability of the compression ratio adjusting mechanism 7 is favorably improved due to the fewer parts.

Referring to fig. 1, the eccentric shaft 6 may include: the driving shaft 61 is rotatably arranged on the cylinder body, the eccentric wheel 62 is eccentrically sleeved on the driving shaft 61, and the eccentric wheel 62 is fixed relative to the driving shaft 61. A first end of the control link 5 is hinged to the lower link 3, and a second end of the control link 5 is hinged to the driving shaft 61 via an eccentric 62, thereby allowing the control link 5 and the lower link 3 to rotate relative to each other and the control link 5 and the driving shaft 61 to rotate relative to each other.

Further, the compression ratio adjustment mechanism 7 may further include: and the driving device is connected with the driving shaft 61 and is used for driving the driving shaft 61 to rotate. Specifically, the drive device provides a drive torque to the drive shaft 61 to rotate the drive shaft 61.

The first end of the upper connecting rod 2 is hinged with the piston 1 through a piston pin A, and the second end of the upper connecting rod 2 is hinged with the lower connecting rod 3 through a connecting rod pin B.

Referring to fig. 1 to 3, further, the first end of the control link 5 is hinged to the lower link 3 by a control link pin D, and the link pin B and the control link pin D are disposed at two sides of a link neck 42 sleeved on the lower link 3. In other words, the lower link 3 is provided with the upper link pin hole 311 and the control link pin hole 321, and the upper link pin hole 311 and the control link pin hole 321 are provided at both sides of the central hole 33 of the lower link 3, and preferably, a line connecting the center lines of the upper link pin hole 311 and the control link pin hole 321 passes through the center line of the central hole 33. Link pin B is located in upper link pin hole 311 and control link pin D is located in control link pin hole 321.

The crankshaft 4 is disposed between the piston 1 and the eccentric shaft 6, thereby bringing the crankshaft 4 closer to the piston 1 so that kinetic energy of the piston 1 can be rapidly transferred to the crankshaft 4 upon combustion of fuel, reducing loss of kinetic energy.

The lower link 3 of the present invention will be described in detail with reference to fig. 1 to 28 in conjunction with the embodiment.

Referring to fig. 2 to 4, 6 to 9, 11 to 21, and 27 to 28, the lower link 3 according to an embodiment of the present invention may include: the upper connecting rod portion 31 and the control connecting rod portion 32, the upper connecting rod portion 31 is connected with the control connecting rod portion 32, at least one connecting point is a rotating connecting point, the upper connecting rod portion 31 and the control connecting rod portion 32 can rotate relatively around the rotating connecting point, so that the upper connecting rod portion 31 and the control connecting rod portion 32 can be rotatably installed on a connecting rod neck 42 of the crankshaft 4, namely, the lower connecting rod 3 is assembled with the crankshaft 4 in a mode of rotating around the rotating connecting point.

Compared with the traditional mode of simply using a plurality of bolts to connect the upper connecting rod part 31 and the control connecting rod part 32, the rotary installation mode in the invention can ensure that at least one end of the upper connecting rod part 31 and the control connecting rod part 32 is assembled in advance at the rotary connection point, and then the opening angle of the upper connecting rod part 31 and the control connecting rod part 32 is changed, so that the upper connecting rod part 31 and the control connecting rod part 32 are matched with the connecting rod neck 42, the assembly process of the lower connecting rod 3 and the crankshaft 4 can be simplified, and the assembly difficulty is reduced.

The rotation axis of the rotation connection point is parallel to the axis of the central hole 33, so that the rotation track of the upper link part 31 and the rotation track of the control link part 32 are in the same plane, and when one end of the upper link part 31 and one end of the control link part 32 rotate relatively at the time of the rotation connection point, the opening angle of the other end of the upper link part 31 and the other end of the control link part 32 can be changed.

According to the lower connecting rod 3 of the embodiment of the invention, the upper connecting rod part 31 and the control connecting rod part 32 can rotate relatively around the rotating connecting point, so that the assembling process of the lower connecting rod 3 and the crankshaft 4 is simplified, and the assembling difficulty is reduced.

Referring to fig. 2 to 4, 6 to 9, 11 to 18, and 27 to 28, at the rotational connection point, the upper link portion 31 and the control link portion 32 are rotationally connected by a hinge pin 53. In other words, the hinge pin 53 passes through the upper link portion 31 and the control link portion 32 to achieve the hinge connection of the upper link portion 31 and the control link portion 32. That is, the hinge pin 53 is at the pivot connection point.

Further, as shown in fig. 2 to 4, 6 to 7, 9, 11 to 21, and 27 to 28, one of the upper link portion 31 and the control link portion 32 is provided with a hinge seat 51, the other is provided with a connecting arm 52, the hinge seat 51 and the connecting arm 52 are provided with hinge pin holes 54 for mounting hinge pins 53, and the hinge pins 53 pass through the hinge pin holes 54 of the hinge seat 51 and the hinge pin holes 54 of the connecting arm 52, thereby realizing the hinge connection of the upper link portion 31 and the control link portion 32 at the hinge pins 53. The hinge pin 53, the hinge socket 51 and the connecting arm 52 constitute a hinge structure where the above-mentioned pivotal connection point is formed.

For example, in the embodiment shown in fig. 11-12, 15, 20-21, the upper link portion 31 is provided with a socket 51 and the control link portion 32 is provided with a connecting arm 52. In the embodiment shown in fig. 2-4, 6-7, 9, 13-14, 16-19, 27-28, the control link part 32 is provided with a hinge socket 51 and the upper link part 31 is provided with a connecting arm 52.

Alternatively, as shown in fig. 7 to 8, 12 to 15, and 19 to 20, the connecting arm 52 includes a first connecting arm 521 and a second connecting arm 522, the first connecting arm 521 and the second connecting arm 522 are spaced apart along the axial direction of the hinge pin 53, the hinge seat 51 is sandwiched between the first connecting arm 521 and the second connecting arm 522, and the hinge pin 53 sequentially passes through the first connecting arm 521, the hinge seat 51, and the second connecting arm 522. In other words, the connecting arm 52 is a bifurcated structure supporting both ends of the hinge socket 51. The hinge hole seat 51 is a convex structure, and the hinge hole seat 51 is positioned on the inner side of the connecting arm 52 after assembly and supports the middle part of the hinge pin 53. The hinge pin 53 connects the upper link part 31 and the control link part 32 of the lower link 3 together through the hinge hole seat 51 and the hinge pin hole 54 of the connecting arm 52, while the upper link part 31 and the control link part 32 can relatively rotate about the hinge pin 53 to change the opening angle of the upper link part 31 and the control link part 32.

Alternatively, in the embodiment shown in fig. 7-8, 12, 19, the reaming base 51 is a single reaming base 51.

Alternatively, in the embodiment shown in fig. 13-15 and 20, the hinge socket 51 includes a first hinge socket 511 and a second hinge socket 512, and the first hinge socket 511 and the second hinge socket 512 are spaced along the axial direction of the hinge pin 53, so that the thickness of the hinge socket 51 can be reduced, and the material of the hinge socket 51 can be saved, and the hinge pin hole 54 is disposed on each of the first hinge socket 511 and the second hinge socket 512. When the hinge seat 51 is sandwiched between the first connecting arm 521 and the second connecting arm 522, the first hinge seat 511 is attached to the first connecting arm 521, the second hinge seat 512 is attached to the second connecting arm 522, and the hinge pin 53 sequentially passes through the hinge pin holes 54 of the first connecting arm 521, the first hinge seat 511, the second hinge seat 512, and the second connecting arm 522, so as to connect the upper link portion 31 and the control link portion 32 together.

In some embodiments of the present invention, as shown in fig. 6, 9, and 17, a parting surface 40 is formed between the upper link part 31 and the control link part 32, the lower link 3 is divided into two parts at the parting surface 40, and both the surface of the upper link part 31 facing the control link part 32 and the surface of the control link part 32 facing the upper link part 31 are the parting surface 40.

Referring to fig. 7, 12, 14-15, and 19-20, the upper connecting rod portion 31 is provided with an upper central half-hole 316, the control connecting rod portion 32 is provided with a lower central half-hole 326, the upper central half-hole 316 and the lower central half-hole 326 surround a central hole 33, the central hole 33 is adapted to be sleeved on the connecting rod neck 42 of the crankshaft 4, and the crankshaft 4 drives the lower connecting rod 3 to move when rotating.

The plane of parting plane 40 is disposed through the axis of central bore 33, thereby facilitating weight balance between upper link portion 31 and control link portion 32, facilitating dynamic balance performance of lower link 3, and facilitating simplification of the machining process of upper link portion 31 and control link portion 32.

The hinge socket 51, which mainly serves to connect the upper link part 31 and the control link part 32 and to support the hinge pin 53, may be provided on either side of the parting surface 40 of the lower link 3, and the hinge socket 51 may be provided on the other side of the parting surface 40 of the lower link 3.

There are two main types of structures of the hinge hole seat 51 on the parting surface 40 side of the lower connecting rod 3. In the first configuration, the hinge eye seat 51 and the upper link pin hole 311 are both located on the upper link portion 31, as shown in fig. 11-12, 15, 20-21. The upper link part 31 is a bifurcated structure, supports both ends of the link pin B, and the upper link part 31 and the reaming base 51 form a Y-shaped structure, wherein the reaming base 51 is a Y-shaped bottom, and the upper link part 31 is a Y-shaped top. When the structure is stressed, stress concentration is easy to occur at the joint of the reaming seat 51 and the upper connecting rod part 31, and the joint transition of the reaming seat and the upper connecting rod part is in large arc transition. Meanwhile, in the embodiment of fig. 11 and 21, in order to avoid the movement track of the upper link 2 connected to the upper link pin hole 311, an avoiding groove is provided at the joint of the hinge hole seat 51 and the upper link part 31. In the second configuration, the hinge eye mount 51 and the control link pin hole 321 are both located at the control link portion 32, as shown in fig. 2-4, 6-7, 9, 13-14, 16-19, and 27-28. In the structure, an avoiding groove is not required to be arranged on the reaming base 51, so that the reaming base 51 is slightly superior to the first structure in terms of stress and rigidity, and the machining process is simple because the avoiding groove is not arranged any more.

Further, as shown in fig. 9 and 11, the axis of the hinge pin hole 54 is located in the plane of the parting plane 40, that is, the axis of the hinge pin 53 is located in the plane of the parting plane 40, that is, the plane of the parting plane 40 passes through the center of the hinge pin 53, so that the lower connecting rod 3 is prevented from interfering with the crankshaft 4 during the assembling process, and the assembling work is ensured to be performed smoothly.

Alternatively, the axis of the hinge pin hole 54 is parallel to the axis of the central hole 33, and when the upper link portion 31 and the control link portion 32 rotate relatively, the rotation center line is the axis of the hinge pin hole 54, thereby ensuring that the rotation locus of the upper link portion 31 and the rotation locus of the control link portion 32 are in the same plane.

In some embodiments of the present invention, referring to fig. 7, 12 to 16, 19 to 21, and 27 to 28, the upper link portion 31 is provided with an upper link pin hole 311, and the control link portion 32 is provided with a control link pin hole 321, and as shown in fig. 11, when viewed from the axial direction of the lower link 3, the parting plane 40 includes: an upper segment land 401 adjacent upper link pin bore 311 and a lower segment land 402 adjacent control link pin bore 321, hinge pin 53 being located at upper segment land 401.

In some embodiments of the present invention, as shown in fig. 3-4, 7, 12-16, one of the connection points of the upper link portion 31 and the control link portion 32 is a threaded connection point.

Further, as shown in fig. 3-4, 7, 13-14, and 16, the upper link portion 31 is provided with an upper link pin hole 311, the control link portion 32 is provided with a control link pin hole 321, the upper link portion 31 and the control link portion 32 enclose a central hole 33, the rotation connection point is located on one side of the central hole 33 close to the upper link pin hole 311, and the screw connection point is located on one side of the central hole 33 close to the control link pin hole 321.

If the distance between the center line of the hinge pin 53 and the center line of the center hole 33 is small, the wall thickness of the center hole 33 near the hinge pin 53 is reduced, and when a force is applied, the deformation generated in the reduced area is large, so that the failure risk of the lower connecting rod 3 is increased. On the other hand, if the distance between the center line of the hinge pin 53 and the center line of the center hole 33 is increased, the entire structure of the lower link 3 becomes large, which is disadvantageous to the entire assembly of the lower link 3. Therefore, the distance between the center line of the hinge pin 53 and the center line of the center hole 33 is preferably in the range of 39mm to 45 mm.

Alternatively, a connecting bolt 35 is provided at the screw-coupling point, and when the lower connecting rod 3 is assembled with the neck 42 of the crankshaft 4, the upper connecting rod portion 31 is hinge-coupled with one end of the control connecting rod portion 32 using the hinge pin 53, and then at least one of the upper connecting rod portion 31 and the control connecting rod portion 32 is rotated to increase the opening angle of the upper connecting rod portion 31 and the control connecting rod portion 32, thereby facilitating the setting of the upper connecting rod portion 31 and the control connecting rod portion 32 on the neck 42 of the crankshaft 4, and then the upper connecting rod portion 31 and the control connecting rod portion 32 are rotated in the opposite direction to bring the upper connecting rod portion 31 into contact with the other end of the control connecting rod portion 32 and fixed using the connecting bolt 35 at the contact position, thereby completing the assembly of the lower connecting rod 3 with the crankshaft 4.

Alternatively, the central axis of the link bolt 35 is perpendicular to the central axis of the hinge pin 53, thereby facilitating the tightening or loosening operation of the link bolt 35.

Referring to fig. 12 and 15, a second bolt hole 323 is formed in the control link portion 32, a first threaded hole 314 (not shown in fig. 15) is formed in the upper link portion 31, and the link bolt 35 is inserted through the second bolt hole 323 and then screwed into the first threaded hole 314, so that the upper link portion 31 and the control link portion 32 are screwed at a screw connection point.

Referring to fig. 3 and 14, a second threaded hole 324 is formed in the control link portion 32, a first bolt hole (not shown in fig. 3 and 14) is formed in the upper link portion 31, and the link bolt 35 is threaded through the first bolt hole and then screwed into the second threaded hole 324, so that the upper link portion 31 and the control link portion 32 are screwed at a screw connection point.

The force applied to the lower link 3 will be described with reference to fig. 9 to 10.

In fig. 9-10 and 17, Fa ' are the forces of control link 5 on lower link 3, Fb ' are the resultant forces exerted on lower link 3, Fc ' are the forces of upper link 2 on lower link 3, Fx ' are the shear forces, Fy ' are the pressing forces. When the engine is operated, the explosion pressure of the cylinder is transmitted to the upper connecting rod 2 through the piston 1, and the upper connecting rod 2 transmits a force Fc to the lower connecting rod 3. Fc generates a component force, which is a shearing force Fx, at the parting surface 40 of the lower link 3.

Fig. 10 is a force analysis diagram of the upper link portion 31 and the control link portion 32 connected at both ends by the link bolt 35, Fx' acts on the link bolt 35, and the shear resistance of the link bolt 35 is weak, so that the left link bolt 35 shown in fig. 10 is easily damaged. In the structure of the lower link 3 shown in fig. 10, in order to reduce the shearing force Fx ' applied to the link bolt 35, it is necessary to ensure that the direction of the force Fc ' transmitted from the upper link 2 to the lower link 3 is substantially perpendicular to the parting plane 40 of the lower link 3 at a time near the maximum explosive pressure of the engine, and at this time, the range of the included angle θ ' between the parting plane 40 and the connecting line between the upper link pin hole 311 and the control link pin hole 321 is small, which is not beneficial to the adjustment of the structure and size of the lower link 3.

Fig. 9 is a schematic view showing a force analysis in which the upper link portion 31 and the control link portion 32 are connected at one end by the hinge pin 53 and at the other end by the link bolt 35, and at the maximum explosion pressure of the engine, the lower link 3 is subjected to a force that tensions the control link portion 32 and the upper link portion 31 is pressed. When the inertia force is maximum, the control link portion 32 is pressed by the force applied to the lower link 3, and the upper link portion 31 is tensioned. Since the maximum explosive pressure is much larger than the maximum inertia force, the hinge pin 53 is more stressed near the upper link pin hole 311 than the hinge pin 53 is stressed near the control link pin hole 321, and thus the hinge pin 53 is preferably designed near the upper link pin hole 311, as shown in fig. 2 to 4, 6 to 7, 9, 11, 13 to 14, 16 to 19, 21, and 27 to 28. Because the lower connecting rod 3 adopts the hinge pin 53, the shearing force Fx acts on the hinge pin 53 through the hinge hole seat 51 and the connecting arm 52, and finally the hinge pin 53 overcomes the shearing force Fx, and the shearing resistance of the hinge pin 53 is obviously superior to that of the connecting rod bolt 35, so that the stress of the lower connecting rod 3 is improved.

In addition, the explosion pressure of the cylinder is transmitted to the force Fc of the lower link 3, so that the upper link portion 31 of the lower link 3 is pressed, and if the connection is performed by the link bolt 35, when the pressing force Fy acts on the link bolt 35, the end of the threaded hole is likely to have stress concentration, resulting in thread failure. And by adopting the hinge structure, the pressing force Fy acts on the hinge pin 53 through the connecting arm 52, and the hinge pin hole 54 on the connecting arm 52 disperses the pressing force Fy along the edge of the hole, so that the hinge pin 53 is stressed uniformly, and the phenomenon of stress concentration caused by connection of the connecting rod bolt 35 is avoided.

In fig. 9, the hinge pin 53 can bear a large shearing force, when the engine is near the maximum explosive pressure, the direction of the force Fc transmitted from the upper link 2 to the lower link 3 may not be nearly perpendicular to the parting plane 40 of the lower link 3, the range of the included angle θ between the parting plane 40 and the connecting line between the upper link pin hole 311 and the control link pin hole 321 is larger than the range of the included angle θ' when the two link bolts 35 are connected, and the included angle θ is between 45 ° and 65 °.

In addition, since the hinge pin 53 itself cannot apply a preload to the lower link 3, a connection manner capable of applying a preload is required at the other end of the lower link 3, and a connection manner of the upper link portion 31 and the link bolt 35 at the other end of the control link portion 32 is a connection manner capable of applying a preload. The connecting rod is connected by the connecting rod bolt 35, so that the overall size, weight and processing difficulty of the lower connecting rod 3 can be reduced. Since the shear force generated on the lower link 3 is mainly overcome by the hinge pin 53, the link bolt 35 is hardly subjected to the shear force, reducing the risk of failure of the link bolt 35. Meanwhile, the connecting rod bolt 35 can adopt a smaller specification, so that the size and the weight of the lower connecting rod 3 can be reduced, and the reciprocating inertia force of the lower connecting rod 3 is reduced.

That is, after the upper link portion 31 and the control link portion 32 are hinged, the stress on the other end of the link bolt 35 is improved, so that the usage specification of the link bolt 35 can be properly reduced to save the cost.

Alternatively, in the embodiment shown in fig. 12, 15, 20, the hinge pin 53 may be designed in a position close to the control link pin hole 321.

To reduce the axial deformation of the lower link 3, one of the hinge pin hole 54 on the link arm 52 and the hinge pin hole 54 on the hinge hole base 51 is in interference fit when engaged with the hinge pin 53. Since the upper link part 31 and the control link part 32 of the lower link 3 are rotatable about the hinge pin 53, the other of the hinge pin hole 54 on the connecting arm 52 and the hinge pin hole 54 on the hinge hole seat 51 may be in clearance fit with the hinge pin 53, for example, in some embodiments of the present invention, referring to fig. 8, the hinge pin 53 is in interference fit with the hinge pin hole 54 of the hinge hole seat 51, and the hinge pin 53 is in clearance fit with the hinge pin hole 54 of the connecting arm 52. However, in order to reduce the risk of separation of the lower connecting rod 3 during operation due to play between the joint pin 53 and the joint pin hole 54, a transition fit is recommended. To further eliminate the gap between the hinge pin 53 and the hinge pin hole 54, after the lower connecting rod 3 and the crankshaft 4 are assembled, pressing force may be applied to both sides of the hinge pin 53 to deform it by force, thereby increasing the radial dimension. In this case, the hinge pin 53 may be in interference fit with the hinge pin hole 54 of the hinge hole seat 51, and the hinge pin 53 may be in transition fit with the hinge pin hole 54 of the connecting arm 52.

In some embodiments of the invention, not shown, the upper link portion 31 and the control link portion 32 are connected by two connection points, both of which are rotational connection points. When the upper connecting rod part 31 and the control connecting rod part 32 are assembled, the upper connecting rod part 31 and the control connecting rod part 32 are hinged at one of the rotary connecting points, then the opening angles of the upper connecting rod part 31 and the control connecting rod part 32 are adjusted, the upper connecting rod part 31 and the control connecting rod part 32 are installed on the crankshaft 4, and finally the upper connecting rod part 31 and the control connecting rod part 32 are fixed at the other rotary connecting point, so that the lower connecting rod 3 is installed on the crankshaft 4.

Referring to fig. 17 to 18, the lower link 3 according to the present invention may include: the engine comprises an upper connecting rod part 31 and a control connecting rod part 32, wherein at least one end of the connection part of the upper connecting rod part 31 and the control connecting rod part 32 is hinged and connected through a hinge pin 53, an upper connecting rod pin hole 311 suitable for being rotatably connected with an upper connecting rod 2 is arranged on the upper connecting rod part 31, a projection area Q is formed in the extension direction of the connection line of the axis of a piston pin A and the axis of a connecting rod pin B by the upper connecting rod pin hole 311, and when the engine is under the maximum explosion pressure, the hinge pin 53 is positioned in the projection area Q.

Fig. 17 is also a schematic diagram of the force applied to the lower link 3 when the engine is in the vicinity of the maximum explosion pressure time, specifically, when the hinge pin 53 is in the projection region Q and the engine is operated to the vicinity of the maximum explosion pressure time, the force acting on the lower link 3 from the upper link 2 in the direction of the arrow in fig. 17 is Fc, and the force Fc is resolved in the direction of the parting plane 40 of the lower link 3, and the two force components are: a shearing force Fx in the direction of the parting plane 40, and a pressing force Fy in the direction perpendicular to the parting plane. The force Fy presses the upper link part 31 of the lower link 3, and near the moment of the maximum explosive pressure, the force Fc is near the maximum value, so that the component force Fy is also relatively large, and the risk of separation of the bearing bush C caused by the gap between the hinge pin 53 and the hinge pin hole 54 is effectively reduced. When hinge pin 53 is located in projection area Q, parting plane 40 of lower link 3 is closest to perpendicular to force Fc, i.e. β is approximately equal to 90 °, so that shearing force Fx is small, and shearing force Fx is mainly borne by hinge pin 53, so that link bolt 35 is substantially free from shearing force, and the stress requirement on link bolt 35 is reduced.

According to the lower link 3 of the embodiment of the present invention, the hinge pin 53 is located in the projection area Q when the engine is at the maximum explosion pressure, whereby the stress of the lower link 3 can be improved.

In some embodiments of the present invention, as shown in fig. 7 and 17, the control link portion 32 is provided with a control link pin hole 321, an included angle between a central connecting line of the upper link pin hole 311 and the control link pin hole 321 and the parting plane 40 is θ, where θ satisfies: theta is more than or equal to 45 degrees and less than or equal to 65 degrees.

In some embodiments of the invention, and as shown in connection with fig. 17-18, the area between the projected area Q and the central aperture 33 is provided with stiffening ribs 38 to increase the strength and rigidity of that area.

Further, as shown in fig. 18, there is an interference region between the projected region Q and the center hole 33, and the rib 38 is located at least partially in the projected region Q between the interference region and the upper link pin hole 311.

Specifically, the maximum ratio of the interference area to the central hole 33 is not more than 1% so as to avoid the influence of the overlarge interference area on the bearing performance of the lower connecting rod 3.

Specifically, as shown in fig. 17, a force transmitted from the upper link 2 acts on the lower link 3 through the upper link pin hole 311 in the direction of the arrow, and this force causes deformation in the vicinity of the upper link pin hole 311, so that the distance between the upper link pin hole 311 and the center hole 33 can be shortened to increase the overall rigidity in the vicinity of the upper link pin hole 311. Since the distance between the upper link pin hole 311 and the center hole 33 is shortened, the overall size of the lower link 3 is reduced, making the engine mechanism more compact. Meanwhile, the weight of the lower connecting rod 3 is reduced, the lower connecting rod 3 is lighter, and the inertia force borne by the lower connecting rod is reduced.

The distance between the upper link pin hole 311 and the center hole 33 is shortened so that, in the vicinity of the highest compression ratio of the engine, a projected area Q of the link pin B projected along a straight line passing through the centers of the piston pin a and the link pin B during operation of the mechanism slightly interferes with the center hole 33, that is, an interference area exists between the projected area Q and the center hole 33, and the area of the maximum interference area of the projected area Q and the center hole 33 is about 0.4% of the area of the center hole 33. In the vicinity of the highest compression ratio range, the working condition of the engine is low load, and because the maximum explosion pressure of the low-load working condition is much lower than that of the high-load working condition, under the working condition, the slight interference between the projection region Q and the central hole 33 region has a stress deformation influence on the central hole 33, and the problem can be solved by improving the structural strength of the lower connecting rod 3 in the interference region. The structural rigidity can be enhanced by adjusting the positions of the reinforcing ribs 38 so that the positions of the reinforcing ribs 38 are included in the projection area Q, and the enhancement of the structural rigidity can eliminate the negative influence caused by the deformation under force.

In some embodiments of the present invention, one of the connection points of the upper link portion 31 and the control link portion 32 is a screw connection point, and the screw connection point is located outside the projection area Q. For example, in fig. 17, the hinge pin 53 is located on the left side of the central bore 33 and the bolted connection point is located on the right side of the central bore 33.

In some embodiments of the present invention, the inner surfaces of the upper center half hole 316 and the lower center half hole 326 are provided with the wear-resistant coating, so that the wear-resistant performance of the inner surfaces of the upper center half hole 316 and the lower center half hole 326 can be improved, and thus, when the lower connecting rod 3 is assembled with the connecting rod journal 42 of the crankshaft 4, the bearing bush C can be eliminated, and the wear-resistant coating can replace the bearing bush C, thereby reducing the number of parts and simplifying the assembly process.

Referring to fig. 19 to 21, the lower link 3 according to the present invention may include: the connecting structure comprises an upper connecting rod part 31 and a control connecting rod part 32, wherein at least one end of the connecting part of the upper connecting rod part 31 and the control connecting rod part 32 is rotatably connected, so that the upper connecting rod part 31 and the control connecting rod part 32 can rotate relatively around a rotating connecting point.

Referring to fig. 21, the angle of relative rotation between the upper link part 31 and the control link part 32 is α, which is in the range of 0 ° -170 °, for example, the opening angle α of the upper link part 31 and the control link part 32 around the hinge pin 53 can reach 160 ° -170 °, and the lower link 3 can be conveniently placed in the cylinder hole during assembly by adjusting the opening angle of the upper link part 31 and the control link part 32.

In some embodiments of the present invention, one of the upper link portion 31 and the control link portion 32 is provided with a hinge seat 51, and the other is provided with a connecting arm 52, and the hinge seat 51 and the connecting arm 52 are rotatably connected.

Further, there is at least one hinge hole seat 51 and at least one connecting arm 52.

For example, in some embodiments not shown, the hinge socket 51 and the link arm 52 are each one, and the hinge socket 51 and the link arm 52 are disposed adjacent to each other.

In some embodiments of the present invention, the thicknesses of the upper link part 31 and the control link part 32 are equal, and the sum of the thicknesses of the reaming base 51 and the connecting arm 52 is equal to the thickness of the upper link part 31 or the control link part 32, thereby being advantageous in ensuring weight balance of the two parts of the lower link 3.

Further, the upper link part 31 is provided with an upper link pin hole 311, the control link part 32 is provided with a control link pin hole 321, and in the embodiment of fig. 11 and 21, the hinge hole seat 51 is also located at a position close to the upper link pin hole 311, so that an avoiding groove is provided on the hinge hole seat 51, and the avoiding groove is recessed in a direction away from the upper link pin hole 311 to avoid a movement track of the upper link 2 connected to the upper link pin hole 311.

Further, as shown in fig. 9 and 11, the center of the rotational connection point is located in the plane of the parting plane 40, that is, the plane of the parting plane 40 passes through the center of the rotational connection point, thereby preventing the lower connecting rod 3 from interfering with the crankshaft 4 during the assembly process.

Referring to fig. 3 to 4, 7, and 12 to 16, the lower link 3 according to the present invention may include: the upper connecting rod portion 31 and the control connecting rod portion 32, the upper connecting rod portion 31 is connected with the control connecting rod portion 32, one of the connecting points is a rotating connecting point, and the other connecting point is an adjustable connecting point.

As shown in fig. 22 to 28, a parting surface 40 is formed between the upper link part 31 and the control link part 32, and a boss 37 is provided at the parting surface 40 at one end of the upper link part 31 rotatably connected to the control link part 32.

At the rotational connection point, the hinge pin 53 passes through the hinge pin hole 54 of the upper link portion 31 and the control link portion 32, thereby achieving rotational connection of the upper link portion 31 and the control link portion 32. Due to the clearance between the hinge pin hole 54 and the hinge pin 53, the risk of the bearing shell C separating during operation of the engine is increased. The risk of separation of the bearing shells C can be reduced by providing a boss 37 at the parting plane 40 at the point of the rotary joint and applying an adjusting force at the point of the adjustable joint. Specifically, due to the lever principle, when a small adjusting force is applied to the adjustable connecting point, the boss 37 can generate large deformation, so that the lower connecting rod 3 can apply large pretightening force to the bearing bush C, and the risk of separation of the bearing bush C is reduced. Meanwhile, the pretightening force can also prevent the deformation of the central hole 33 of the lower connecting rod 3 caused by the elastic tension of the bearing bush C.

According to the lower connecting rod 3, the boss 37 is arranged on the parting surface 40 at the rotary connecting point, and the adjusting force is applied to the adjustable connecting point, so that the boss 37 can be greatly deformed, the lower connecting rod 3 can apply a large pre-tightening force to the bearing bush C, and the risk of separating the bearing bush C is reduced.

In some embodiments of the present invention, referring to fig. 3, 7, 12, 14-15, the upper link portion 31 is provided with an upper central half-hole 316, the control link portion 32 is provided with a lower central half-hole 326, the upper central half-hole 316 and the lower central half-hole 326 enclose a central hole 33, the adjustable connection points are bolt connection points, and the bolt connection points and the rotation connection points are distributed on parting surfaces 40 at two sides of the central hole 33. The connecting rod bolt 35 is arranged at the screwed connection point, and the size of the adjusting force can be changed by changing the screwing degree of the connecting rod bolt 35, so that the pre-tightening force applied to the bearing bush C by the lower connecting rod 3 is changed.

In some embodiments of the present invention, the hinge socket 51 is disposed at one end of the parting surface 40, and the boss 37 is disposed on the parting surface 40 on one side of the hinge socket 51, as shown in fig. 25, the hinge socket 51 is disposed on the control link portion 32, and both the boss 37 and the hinge socket 51 extend from the parting surface 40 of the control link portion 32 and extend toward the parting surface 40 of the upper link portion 31, and when the upper link portion 31 and the control link portion 32 are assembled and the link bolt 35 at the adjustable connection point is tightened, the boss 37 and the parting surface 40 of the upper link portion 31 are deformed by contact, so as to increase the preload of the lower link 3 on the bearing bush C.

In other embodiments of the present invention, the connecting arm 52 is disposed at one end of the parting surface 40, and the boss 37 is disposed on the parting surface 40 on the side of the connecting arm 52, as shown in fig. 22-24, the connecting arm 52 is disposed on the upper link part 31, and the boss 37 and the connecting arm 52 both extend from the parting surface 40 of the upper link part 31 and extend toward the parting surface 40 of the control link part 32, so that the hinge seat boss 371 and the parting surface 40 of the control link part 32 are deformed by contact when the upper link part 31 and the control link part 32 are assembled and the link bolt 35 at the adjustable connecting point is tightened, to increase the preload of the lower link 3 on the bearing bush C.

In some other alternative embodiments of the present invention, the reaming base 51 and the connecting arm 52 each extend from the corresponding parting plane 40, and the boss 37 includes: the bearing bush comprises a reaming seat boss 371 and a connecting arm boss 372, wherein the reaming seat boss 371 extends from a parting surface 40 where a reaming seat 51 is located, and the connecting arm boss 372 extends from the parting surface 40 where a connecting arm 52 is located, that is, bosses 37 are arranged on the reaming seat 51 and the parting surface 40 where the connecting arm 52 is located, for example, a reaming seat 51 and a reaming seat boss 371 are arranged on the parting surface 40 of a control connecting rod part 32, and a connecting arm 52 and a connecting arm boss 372 are arranged on the parting surface 40 of an upper connecting rod part 31, so that when the connecting rod bolt 35 at an adjustable connecting point is screwed after the upper connecting rod part 31 and the control connecting rod part 32 are assembled, the reaming seat boss 371 and the connecting arm boss 372 are in contact with each other to deform, and the pre-tightening force of a lower connecting rod 3 on a bearing bush.

In some embodiments of the present invention, as shown in fig. 27-28, the lower connecting rod 3 further includes a bearing bush C respectively disposed in the upper connecting rod portion 31 and the control connecting rod portion 32, the two bearing bushes C are mounted in the central hole 33 in a relatively engaged manner, and as shown in fig. 25-26, the thickness of the boss 37 is not less than the height 91 of the rest surface of the corresponding bearing bush C, thereby ensuring that the boss 37 can be deformed to preload the bearing bush C when the adjusting force for adjusting the adjustable connecting point is large. Specifically, the bush C provided in the upper link part 31 is the upper bush 81, the bush C provided in the control link part 32 is the lower bush 82, and the boss 37 on the parting surface 40 of the control link part 32 is not less in thickness than the height 91 of the residual surface of the lower bush 82, taking the control link part 32 as an example.

In some embodiments of the present invention, the boss 37 is an elongated boss 37, which facilitates the processing, and the length direction of the boss 37 is parallel to the axis of the central hole 33. The number of the bosses 37 is at least one.

An engine according to another aspect of the present invention includes the lower link 3 of the above embodiment. Compared with the prior art, the engine has the following advantages:

(1) after the engine of the invention adopts the lower connecting rod 3, at least one connecting point of the upper connecting rod part 31 and the control connecting rod part 32 is a rotating connecting point, thereby facilitating the assembly of the lower connecting rod 3 and the crankshaft 4 and improving the stress of the lower connecting rod 3.

(2) According to the engine, the boss 37 is arranged on the parting surface 40 at one end, rotatably connected with the control connecting rod part 32, of the upper connecting rod part 31, so that the bearing bush C can be pre-tightened, and the risk of separation of the bearing bush C is reduced.

Referring to fig. 1 to 5 and 25 to 28, an upper bearing bush 81 is disposed between the upper center half hole 316 and the connecting rod neck 42, a lower bearing bush 82 is disposed between the lower center half hole 326 and the connecting rod neck 42, the upper bearing bush 81 and the lower bearing bush 82 are mounted in the central hole 33 of the lower connecting rod 3 in a relatively engaging manner, and before the upper connecting rod portion 31 and the control connecting rod portion 32 are assembled, the height 91 of the upper bearing bush 81 and/or the height 91 of the lower bearing bush 82 is greater than 0, that is, only the height 91 of the upper bearing bush 81 may be greater than 0, only the height 91 of the lower bearing bush 82 may be greater than 0, and both the heights 91 of the upper bearing bush 81 and the lower bearing bush 82 may be greater than 0. For convenience of description, only the above-mentioned example in which the height 91 of the remaining surface of the upper bush 81 and the lower bush 82 is greater than 0 is described below.

By increasing the height 91 of the residual surface of the upper bearing bush 81 and the lower bearing bush 82, the assembling pretightening force of the upper bearing bush 81 and the lower bearing bush 82 is increased, the joint rate of the upper bearing bush 81 and the lower bearing bush 82 is increased, and the failure risk caused by the separation of the upper bearing bush 81 and the lower bearing bush 82 is reduced.

According to the engine, the height 91 of the residual surfaces of the upper bearing bush 81 and the lower bearing bush 82 is set to be larger than 0, so that the assembling pretightening force of the upper bearing bush 81 and the lower bearing bush 82 can be increased, the attaching rate of the upper bearing bush 81 and the lower bearing bush 82 is increased, and the separation risk of the upper bearing bush 81 and the lower bearing bush 82 is reduced.

In some embodiments of the present invention, the upper link portion 31 is provided with an upper link pin hole 311, the upper link pin hole 311 is hinged to the upper link 2, the control link portion 32 is provided with a control link pin hole 321, and the control link pin hole 321 is hinged to the control link 5.

Further, the upper link portion 31 and the control link portion 32 have two connection points to fix the upper link portion 31 and the control link portion 32, and the two connection points are located at two sides of a connection line between the upper link pin hole 311 and the control link pin hole 321.

In the embodiments shown in fig. 3-4, 7, 12-16, one of the connection points is a pivot connection point and the other connection point is a bolt connection point.

In some embodiments, not shown, both attachment points are rotational attachment points.

In other embodiments, not shown, both attachment points are bolted attachment points.

In some embodiments of the present invention, the height 91 of the remaining surface of the upper bearing bush 81 and the lower bearing bush 82 is 60 μm to 100 μm.

Meanwhile, the increase of the pretightening force of the bearing bush C can lead to the increase of the stress deformation of the upper bearing bush 81 and the lower bearing bush 82, and the overall thickness of the bearing bush C should be correspondingly increased for reducing the deformation of the upper bearing bush 81 and the lower bearing bush 82. In some embodiments of the present invention, the thickness of the upper bearing bush 81 and the lower bearing bush 82 is 1.6mm to 2 mm. By increasing the thickness of the upper shell 81 and the lower shell 82, the amount of deformation of the upper shell 81 and the lower shell 82 can be reduced.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A lower connecting rod (3), characterized in that a central hole (33) cooperating with a crankshaft (4) is provided in the lower connecting rod (3), the lower connecting rod (3) comprising: go up connecting rod portion (31), control connecting rod portion (32), go up connecting rod portion (31) with control connecting rod portion (32) are connected, and at least one tie point is the rotation tie point, the axis of rotation tie point with the axis of centre bore (33) is parallel.

2. A lower link (3) according to claim 1, characterized in that at the rotational connection point the upper link part (31) and the control link part (32) are rotationally connected by means of a hinge pin (53).

3. A lower link (3) according to claim 2, wherein one of the upper link portion (31) and the control link portion (32) is provided with a hinge hole seat (51) and the other is provided with a connecting arm (52), and the hinge hole seat (51) and the connecting arm (52) are provided with a hinge pin hole (54) for mounting the hinge pin (53).

4. A lower link (3) according to claim 3, wherein the connecting arm (52) comprises a first connecting arm (521) and a second connecting arm (522) arranged at intervals along the axial direction of the hinge pin (53), and the hinge hole seat (51) is interposed between the first connecting arm (521) and the second connecting arm (522).

5. A lower link (3) according to claim 3 or 4, characterized in that the reaming socket (51) is a single reaming socket (51).

6. The lower connecting rod (3) according to claim 3 or 4, wherein the hinge socket (51) comprises a first hinge socket (511) and a second hinge socket (512) spaced apart from each other along the axial direction of the hinge pin (53), and the hinge pin hole (54) is formed in the first hinge socket (511) and the second hinge socket (512).

7. A lower connecting rod (3) according to claim 3, characterized in that a parting plane (40) is formed between the upper connecting rod part (31) and the control connecting rod part (32), and an upper central half-hole (316) is provided on the upper connecting rod part (31), and a lower central half-hole (326) is provided on the control connecting rod part (32), and the upper central half-hole (316) and the lower central half-hole (326) enclose the central hole (33), and the parting plane (40) is arranged through the axis of the central hole (33).

8. The lower connecting rod (3) according to claim 7, wherein the axis of the hinge pin hole (54) lies in the plane of the parting plane (40).

9. The lower link (3) according to claim 7, wherein the upper link portion (31) is provided with an upper link pin hole (311), the control link portion (32) is provided with a control link pin hole (321), and the parting surface (40) includes, as viewed in an axial direction of the center hole (33) of the lower link (3): the hinge pin is characterized by comprising an upper section parting surface (401) close to the upper connecting rod pin hole (311) and a lower section parting surface (402) close to the control connecting rod pin hole (321), and the hinge pin (53) is located at the upper section parting surface (401).

10. A lower link (3) according to claim 2, characterized in that one of the connection points of the upper link portion (31) and the control link portion (32) is a threaded connection point.

11. The lower connecting rod (3) according to claim 10, wherein the upper connecting rod portion (31) is provided with an upper connecting rod pin hole (311), the control connecting rod portion (32) is provided with a control connecting rod pin hole (321), the upper connecting rod portion (31) and the control connecting rod portion (32) enclose the central hole (33), the rotation connection point is located on one side of the central hole (33) close to the upper connecting rod pin hole (311), and the screw connection point is located on one side of the central hole (33) close to the control connecting rod pin hole (321).

12. The lower connecting rod (3) according to claim 10, characterized in that a bolt (35) is provided at the screw connection point, the central axis of the bolt (35) being perpendicular to the central axis of the hinge pin (53).

13. The lower connecting rod (3) according to claim 3, wherein one of the hinge pin hole (54) on the connecting arm (52) and the hinge pin hole (54) on the hinge hole seat (51) is an interference fit when engaged with the hinge pin (53), and the other is a clearance fit when engaged with the hinge pin (53).

14. A lower link (3) according to claim 1, characterized in that the upper link part (31) and the control link part (32) are connected by two connection points, and both connection points are rotational connection points.

15. An engine, comprising:

a piston (1), said piston (1) being adapted to move within a cylinder of said engine;

a crankshaft (4), a main journal (41) of the crankshaft (4) being rotatably provided on a cylinder block of the engine;

the lower connecting rod (3) according to any one of claims 1 to 14, the lower connecting rod (3) being fitted over a connecting rod journal (42) of the crankshaft (4);

the upper connecting rod (2), the said upper connecting rod (2) is connected between said piston (1) and said lower connecting rod (3);

a compression ratio adjustment mechanism (7), the compression ratio adjustment mechanism (7) for adjusting the position of the piston (1) within the cylinder, the compression ratio adjustment mechanism (7) comprising: the control connecting rod (5), the control connecting rod (5) with lower connecting rod (3) are articulated.