CN114763808A

CN114763808A - Scotch yoke assembly and method of assembling the same

Info

Publication number: CN114763808A
Application number: CN202110049072.5A
Authority: CN
Inventors: 刘涛; 赖海鹏; 张树旻; 刘君宇; 尹吉; 渠娜; 杨乐; 钟德华; 朱久莹; 邢海军; 郭培; 张东华
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2022-07-19

Abstract

The invention provides a Scotch yoke component and an assembling method thereof. According to the Scotch yoke assembly, the connecting rod and the sliding block which are of an integrated structure are adopted, so that the characteristics of the integrated structure of the connecting rod and the sliding block can be utilized, the overall mass of the assembly is reduced, the inertia force borne by the assembly is reduced, and the assembly of the overall assembly is facilitated.

Description

Scotch yoke assembly and method of assembling the same

Technical Field

The invention relates to the technical field of engines, in particular to a Scotch yoke assembly. Also, the present invention relates to a method of assembling the scotch yoke assembly.

Background

The conventional in-line four-cylinder machine is subject to the motion law of Otto cycle, and a balance shaft is required to counteract the vibration of second-order reciprocating inertia force, so that the weight of the whole machine is increased, and the friction loss is also increased. The Otto cycle in-line six-cylinder machine does not have the vibration problem of second-order inertia force, but has larger mass and volume, more cylinders and difficult reduction of oil consumption. Therefore, from the principle of engine operation, the adoption of the Scotch yoke assembly instead of the traditional Otto cycle structure is a better improved form.

The Scotch yoke assembly has simple operation rule, the track is a simple sine function, no multi-order reciprocating inertia force exists, and perfect balance can be realized. Meanwhile, the Scotch yoke assembly can realize complete opposition of two cylinders, and under the condition of the same displacement and the same cylinder number, the axial length of the Scotch yoke engine is smaller than that of an in-line engine and a horizontally-opposed engine of an Otto cycle, so that the Scotch yoke assembly has good application potential.

However, the conventional scotch yoke assembly has the defects of more assembling parts, complex assembling process, higher overall mass of the assembly and the like, and the application of the scotch yoke assembly is limited to a certain extent.

Disclosure of Invention

In view of the above, the present invention is directed to a scotch yoke assembly, which can reduce the overall assembly quality of the scotch yoke and facilitate the assembly thereof.

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

the utility model provides a scotch yoke subassembly, includes that the middle part is constructed the connecting rod that is the integral type structure that has the slip space, is located the slider in the slip space, and with the bent axle that the slider rotated to be connected, the both ends of connecting rod are equipped with the piston connecting hole respectively, the slider is injectd to be can in the slip space reciprocal straight line slides, just slider formula structure as an organic whole.

Furthermore, the crankshaft is provided with a connecting rod pin, the connecting rod pin penetrates through a connecting rod pin connecting hole on the sliding block, and a bushing sleeved outside the connecting rod pin is fixedly arranged in the connecting rod pin connecting hole.

Furthermore, two opposite side end surfaces of the sliding block are in sliding butt joint with two inner walls of the sliding space to limit the reciprocating linear sliding of the sliding block, and bearing bushes are respectively arranged on the two opposite side end surfaces of the sliding block.

Furthermore, the bearing bush is detachably fixed on the end face of the sliding block.

Further, the bent axle includes the multistage main journals of coaxial arrangement, the connecting rod round pin of bent axle passes through the crank portion and connects in adjacent two between the main journals, just the connecting rod round pin with between the crank portion, and the crank portion with cartridge links firmly respectively between the main journals.

Furthermore, the crank portion comprises two opposite cranks, the connecting rod pin is positioned between the two cranks, and the sliding block penetrated by the connecting rod pin is restrained between the two cranks to form a guide for the sliding block to slide in a reciprocating linear mode.

Furthermore, the cranks are provided with main journal insertion holes and connecting rod pin insertion holes, the main journals and the connecting rod pins on two sides of each crank are respectively inserted into the main journal insertion holes and the connecting rod pin insertion holes in an interference manner, the main journal insertion holes and the connecting rod pin insertion holes are partially overlapped, and at least one of the main journals and the connecting rod pins is provided with an avoiding groove.

Furthermore, a connecting line between the center of the main journal plug hole and the center of the connecting rod pin plug hole is coincident with or approximately coincident with the symmetrical center line of the crank, a planar positioning surface is arranged on the side part of the crank, and a connecting line between the center of the main journal plug hole and the center of the connecting rod pin plug hole is parallel to or approximately parallel to the positioning surface.

Furthermore, a connecting rod oil duct with one end communicated with the outer peripheral surface of the middle part of the connecting rod pin is constructed in the connecting rod pin, a main oil duct capable of being connected with an external oil supply oil path is constructed in the main journal on at least one side of the connecting rod pin, and the main oil duct is connected with the connecting rod oil duct along with the insertion of the connecting rod pin and the main journal on the crank.

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

according to the Scotch yoke assembly, the connecting rod and the sliding block which are of the integrated structure are adopted, so that compared with the existing split combined connecting rod and sliding block structure, the integral quality of the assembly is reduced, the inertia force borne by the assembly is reduced, the assembly of the integral assembly can be facilitated, and the Scotch yoke assembly has good practicability.

In addition, another object of the present invention is to provide an assembling method of a scotch yoke assembly, wherein during assembling, a crank in a crankshaft on one side of a connecting rod pin is pressed and installed, one end of the connecting rod pin is flush with the end surface of the crank on the side, then a slider is sleeved on the connecting rod pin, a connecting rod is assembled, and then the crank on the other side of the connecting rod pin is pressed and installed;

or, the assembling method is that during assembling, the crank in the crank shaft positioned on one side of the connecting rod pin is firstly placed on the support table, then the slider and the connecting rod are assembled, the assembled connecting rod and slider are placed on the end face of the crank on the side, then the crank on the other side is placed on the connecting rod and slider, and then the connecting rod pin is pressed in.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation of the invention. In the drawings:

FIG. 1 is a schematic structural view of a Scotch yoke assembly according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a connecting rod according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a slider according to an embodiment of the present invention;

FIG. 4 is a schematic illustration of a crankshaft according to an embodiment of the present invention;

FIG. 5 is an exploded view of the crankshaft of FIG. 4;

FIG. 6 is a front view of the crankshaft shown in FIG. 4;

FIG. 7 is a schematic structural diagram of a crank according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of a link pin according to an embodiment of the present invention;

fig. 9 is a schematic structural view of a second main journal according to an embodiment of the present invention;

FIG. 10 is a schematic view of a lubrication structure of a crankshaft according to an embodiment of the present invention;

FIG. 11 is a schematic view of another lubrication configuration for a crankshaft according to an embodiment of the present invention;

description of the reference numerals:

1. a cylinder; 2. a piston; 3. a connecting rod; 4. a crankshaft; 5. a slider; 6. a bushing; 7. bearing bushes; 8. a screw;

301. a sliding space; 302. a guide surface; 303. a piston connecting hole;

401. a first main journal; 402. a second main journal; 4021. a second main journal avoidance groove; 4022. an inclined oil duct; 4023. a longitudinal oil passage; 4024. a transverse oil duct; 4025. an oil sump; 4026. the oil duct is communicated; 403. a third main journal; 4031. a third main journal avoidance groove; 404. a link pin; 4041. a connecting rod oil passage; 4042. an oil inlet of the connecting rod oil duct; 4043. a connecting rod oil passage oil outlet; 4044. a first lightening hole; 4045. a second lightening hole; 4046. positioning holes; 405. a crank; 4051. a connecting rod pin insertion hole; 4052. a main journal plug hole; 4053. positioning the surface;

501. a connecting rod pin connecting hole; 502. a connecting rod contact surface.

Detailed Description

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

In the description of the present invention, it should be noted that, if terms indicating orientation or positional relationship such as "upper", "lower", "inside", "outside", etc. appear, they are based on the orientation or positional relationship shown in the drawings and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the appearances of the terms first, second, etc. in this specification are not necessarily all referring to the same item, but are instead intended to cover the same item.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The present embodiment relates to a scotch yoke assembly, which is constructed integrally, as shown in fig. 1, and includes a connecting rod 3 of an integrated structure having a sliding space 301 formed in the middle thereof, a slider 5 located in the sliding space 301, and a crankshaft 4 in which a connecting rod pin 404 is rotatably inserted through the slider 5. The slider 5 is defined to be linearly slidable back and forth in the sliding space 301, and the slider 5 is also formed in an integrated structure.

As shown in fig. 2, the present embodiment is also provided with piston connecting holes 303 at both ends of the connecting rod 3, respectively, the piston connecting holes 303 at each end are used for rotatably connecting the corresponding pistons 2 via piston pins, respectively, the pistons 2 are located in the cylinders 1, and the cylinders 1 of the present embodiment for the engine of the scotch yoke assembly are also horizontally facing.

The piston connecting holes 303 at the two ends of the connecting rod 3 are also symmetrically arranged with respect to the integral connecting rod 3, the sliding space 3 located at the middle part of the connecting rod 3 is substantially rectangular, the two ends of the sliding space penetrate through the connecting rod 3, and two opposite inner walls in the sliding space 301 also respectively form guide surfaces 302 for slidably abutting against the sliding block 5, so that the sliding block 5 linearly slides in the sliding space 301.

As shown in fig. 3, the link pin 404 of the crankshaft 4 of the present embodiment specifically passes through the link pin connecting hole 501 of the slider 5, and in order to reduce friction between the slider 5 and the link pin 404, a bushing 6 sleeved outside the link pin 404 is also fixedly arranged in the link pin connecting hole 501. Meanwhile, the slider 5 of the present embodiment also slidably abuts with the two opposing guide surfaces 302 in the sliding space 301 through the two opposing side end surfaces thereof, that is, the two link contact surfaces 502, to specifically limit the reciprocating linear sliding of the slider 5. In this case, also in view of reducing the friction coefficient between the link contact surface 502 and the guide surface 302, the two link contact surfaces 502 of the slider 5 are provided with the shoes 7, respectively.

The bearing bush 7 is preferably fixed to the end face of the slide 5 in a detachable manner, for example by fixing the bearing bush 7 with a screw 8. In addition, the bearing bush 7 and the bush 6 of the present embodiment may be implemented by using related components for reducing friction, which are commonly used in the prior art.

In this embodiment, the slider 5 and the connecting rod 3 of an integral structure may be formed by casting, or may be formed integrally by machining or other methods. And make both adopt the integral type structure, compare in the current generally used by bolt fastening's components of a whole that can function independently assembled connecting rod structure and slider structure, this embodiment is through giving up the bolt structure, alright effectively avoid bearing the shearing force because of the bolt, and the easy problem that breaks and loosen and take off. At the same time, the integral construction of the connecting rod 3 and the slide 5 also allows for a reduction in weight of both and facilitates assembly thereof in the scotch yoke assembly.

Based on the integrated structure of the connecting rod 3 and the sliding block 5, the crankshaft 4 of the present embodiment is correspondingly of a combined structure, and in this case, the crankshaft 4 integrally includes multiple main journals coaxially arranged, and a connecting rod pin 404 connected between two adjacent main journals through a crank portion. The crank portion includes two opposite cranks 405, the connecting rod pin 404 is located between the two cranks 405, and each crank 405 is fixedly connected with the main journal and the connecting rod pin 404 on two sides of the crank respectively.

According to the above general description of the crankshaft 4, as an exemplary structure of the crankshaft 4 of the combined structure of the present embodiment, as shown in fig. 4 to fig. 6, taking as an example the case where the crankshaft 4 is applied to a four-cylinder engine, that is, the scotch yoke assembly of the present embodiment is applied to a four-cylinder engine, each of the above main journals specifically includes a second main journal 402, and a first main journal 401 and a third main journal 403 which are respectively connected to both ends of the second main journal 402 through two crank portions. The link pin 404 is also specifically two link pins respectively provided at each crank portion, and a portion of the link pin 404 located between the two cranks 405 constitutes a connecting section exposed to be connected to the slider 5, and at the same time, each crank 405 is also connected to a corresponding main journal on the other side thereof.

The cranks 405 of this embodiment have the same structure and, in the specific implementation, as shown in fig. 6, the thickness of the slider 5 should also be substantially equal to the distance D between two adjacent cranks 405, so as to allow the slider 5, through which the connecting rod pin 404 passes, to be constrained between the two cranks 405, so as to be able to constitute a guide for the linear reciprocating sliding of the slider 5 by means of the cranks 405 on both sides. The crank 405 on both sides is used to guide the slider 5, so that the slider 5 can be prevented from being unstable in sliding due to the fact that the inner wall of the sliding space 301 cannot be provided with a guide groove.

As shown in fig. 7, in this embodiment, each crank 405 is respectively provided with a connecting rod pin insertion hole 4051 and a main journal insertion hole 4052, and the main journal and the connecting rod pin 404 on both sides are respectively inserted into the corresponding main journal insertion hole 4052 and the corresponding connecting rod pin insertion hole 4051 in an interference manner.

In addition, as an embodiment, when the radius of the crank is small, the main journal insertion hole 4052 and the link pin insertion hole 4051 may be partially overlapped as shown in fig. 7, and accordingly, an escape groove having an arc-shaped bottom surface may be provided on at least one of the main journal and the link pin 404. In view of the fact that the diameter of the main journal is larger than that of the connecting rod pin 404, the avoiding groove of the present embodiment is also disposed on the main journal, and specifically, it is a third main journal avoiding groove 4031 disposed at one end of the third main journal 403, a second main journal avoiding groove 4021 disposed at both ends of the second main journal 402, and a first main journal avoiding groove similar to the second main journal avoiding groove 4021 and the third main journal avoiding groove 4031 disposed at one end of the first main journal 401.

Still referring to fig. 7, as a preferred embodiment, the line connecting the center of the main journal insertion hole 4052 and the center of the link pin insertion hole 4051 should also coincide or nearly coincide with the center line P of symmetry of the crank 405. Meanwhile, in order to facilitate the assembling operation of the crankshaft 4, the planar positioning surface 4053 is disposed on the side portion of the crank 405 in this embodiment, the positioning surface 4053 may be matched with a tool during the assembling operation of the crankshaft 4, so as to achieve reliable positioning of the crank 405, and to ensure the positioning effect, a connection line between the center of the main journal insertion hole 4052 and the center of the connecting rod pin insertion hole 4051 should be parallel or approximately parallel to the positioning surface 4053.

In the present embodiment, the combined crankshaft suitable for the horizontally facing four-cylinder engine of the present embodiment is assembled by three main journals, each crank 405, and two connecting rod pins 4. And when the above components are assembled, the components are generally fixedly connected with each other in an interference press-fitting mode, so that the structural stability of the assembled crankshaft 4 is ensured. In addition, when the engine is not four cylinders, but two cylinders, six cylinders, or eight cylinders, for example, the structure of the crankshaft 4 of the combined structure for the scotch yoke mechanism may be modified accordingly in accordance with the four-cylinder case of the present embodiment.

As shown in fig. 8, in the present embodiment, a link oil passage 4041 having one end communicating with the outer peripheral surface of the middle portion of the link pin 404 is formed, and a main body oil passage connectable to an external oil supply passage is also formed in the main journal of at least one side of the link pin 404. The position of the outer peripheral surface of the middle portion of the connecting rod pin 404 is also the connecting section of the connecting rod pin 404 for connecting with the slider 5, and with the insertion of the connecting rod pin 404 and the main journal on the crank 405, the main oil duct of the embodiment may be connected with the connecting rod oil duct 401, so as to supply oil to the connecting section in a pressure lubrication manner, thereby realizing lubrication between the connecting rod pin 404 and the slider 5.

In the crankshaft 4 in the form of the four-cylinder engine of the present embodiment, as a preferred embodiment, the main body oil passage in the above-described main journal is specifically configured in the second main journal 402, and it also communicates with the link oil passages 4041 in the two link pins 404, respectively. At this time, as shown in fig. 9 and 10, the main oil gallery located in the second main journal 402 specifically includes two oblique oil galleries 4022, one end of each of the two oblique oil galleries 4022 is connected to an external oil supply oil passage, and the other end thereof is located at the second main journal avoiding groove 4021.

In this embodiment, the diameter of the inclined oil passage 4022 may be between 2 mm and 4mm, and one end of the inclined oil passage 4022 may utilize oil holes and oil supply grooves arranged circumferentially, so as to maintain the inclined oil passage 4022 to be always communicated with an external oil supply passage, thereby achieving uninterrupted oil supply.

In addition, the oblique oil passage 4022 in the present embodiment is also connected to the link oil passage 4041 in the link pin 404 at the second main journal avoiding groove 4021. At this time, in order to prevent the effect of communication between the oblique oil passage 4022 and the link oil passage 4041 from being affected by an installation error, as a preferred embodiment, an oil groove 4025 is also provided on the second main journal 402 at the position of the second main journal avoiding groove 4021, and the oblique oil passage 4022 is connected to the link oil passage 4041 via the oil groove 4025, and a communication port of the link oil passage 4041 connected to the oblique oil passage 4022 is located within a notch range of the oil groove 4025, so as to ensure complete communication.

In this embodiment, the oil groove 4025 is preferably elongated and extends along the circumferential direction of the second main journal 402, and in a specific implementation, the perpendicular distance between the two ends of the oil groove 4025 in the longitudinal direction may be set to be between 6 mm and 20mm, and may be preferably 15 mm.

As a preferred implementation form, the connecting rod oil passage 4041 in the connecting rod pin 404 of the present embodiment is also obliquely arranged, and the connecting rod oil passage oil inlet 4042 at one end is used for communicating with the oil groove 4025, and the connecting rod oil passage oil outlet 4043 at the other end is used for injecting oil to the connecting section for pressure lubrication. In addition, in order to reduce the weight of the link pin 404 and facilitate the lightweight design, weight reduction holes may be respectively formed at both ends of the link pin 404 in the present embodiment.

For convenience of description, the lightening holes at both ends, which are located at the center of the end of the link pin 404 and extend inward of the link pin 404 in the axial direction of the link pin 404, may be referred to as a first lightening hole 4044 and a second lightening hole 4045, respectively. In order to avoid the penetration of the lightening holes and the connecting rod oil passage 4041, the minimum distance between each lightening hole and the connecting rod oil passage 4041 is generally between 5 and 10 mm.

In addition to providing the first lightening hole 4044 and the second lightening hole 4045 at both ends, it is also possible to provide lightening holes at only one end in this embodiment, and it is also possible to provide main oil galleries in the main journals on both sides of the connecting rod pin 404 when lightening holes are provided at only one end. In practical implementation, the diameter of the link oil passage 4041 of the present embodiment may be set between 2 mm and 4mm, and in order to check whether the installation direction and the installation angle of the link pin 404 are appropriate or not in assembly, a positioning hole 4046 indicating the assembly orientation of the link pin 404 may be provided at one end of the link pin 404.

In addition, in addition to using the above-described oblique oil passage 4022 in the second main journal 402 in the crankshaft 4, as another possible implementation form, as shown in fig. 11, the present embodiment may also cause the main body oil passages in the second main journal 402 to specifically include a longitudinal oil passage 4023 in the middle of the second main journal 402 to be connected to an external oil supply oil passage, a lateral oil passage 4024 connected to the longitudinal oil passage 4023, and communication oil passages 4026 that respectively connect the lateral oil passage 4024 and the link oil passages 4041 in the two link pins 404.

In this embodiment, it is preferable that the longitudinal oil passage 4023 has two ends respectively penetrating radially to the outer peripheral surface of the second main journal 402, and is also connected to an external oil passage, that is, an engine block oil passage, and realizes uninterrupted oil supply. Meanwhile, in addition to penetrating both ends of the second main journal 402, it is also possible to penetrate only one end of the longitudinal oil passage 4023, but at this time, the oil supply groove arranged in the circumferential direction should be designed in a full circle form to ensure uninterrupted oil supply.

Further, the lateral oil passage 4024 of the present embodiment is arranged in the middle portion along the axial direction of the second main journal 402, but preferably, two communication oil passages 4026 may also be provided to be arranged radially on the second main journal 402, and each communication oil passage 4024 is also connected to the link oil passage 4041 in the link pin 404 at the position of the second main journal avoiding groove 4021.

In specific implementation, the transverse oil passage 4024 of this embodiment may be formed by axially penetrating and then sealing the two ends with balls. Meanwhile, in order to realize pressure lubrication and also consider reducing the influence on the structural strength of the second main journal 402, the diameters of the longitudinal oil passage 4023 and the transverse oil passage 4024 in the embodiment may be between 3 and 5mm, and preferably 4mm, and the diameter of the communicating oil passage 4026 may be selected between 2 and 3 mm.

In assembling the scotch yoke assembly of this embodiment, as an assembling method, a crank 405 is press-fitted to one side of the link pin 404 so that one end of the link pin 404 is flush with an end surface of the crank 405, and then the slider 5 is fitted over the link pin 404, and the link 3 is assembled. The crank 405 on the other side of the link pin 404 is then press fitted to effect assembly of one of the units. Finally, the main journal is press-fitted to each pre-assembled unit to complete assembly.

Alternatively, as another assembly method, the crank 405 on one side may be placed on the support table, the slider 5 and the connecting rod 3 may be assembled, the assembled connecting rod 3 and slider 5 may be placed on the end face of the crank 405, the crank 405 on the other side may be placed on the connecting rod 3 and slider 5, and then the connecting rod pin 404 may be pressed in to assemble one of the units. Finally, the main journal is press-fitted to each pre-assembled unit, thereby completing assembly of the assembly.

It should be noted that, when assembling each unit, a limit tool should be placed between the cranks 405 on both sides of the connecting rod pin 404 to ensure that the slider 5 and the connecting rod 3 have a certain axial clearance, so as to avoid affecting the relative movement between the connecting rod 3 and the slider 5 and the crankshaft 4.

The scotch yoke assembly of this embodiment is through adopting connecting rod 3 and the slider 5 that are the integral type structure, compares in the connecting rod and the slider structure of current components of a whole that can function independently combination formula, and the characteristics of usable both integral type structures reduce the whole quality of subassembly, reduce the inertia force that the subassembly receives to its assembly that also can be convenient for whole subassembly, and have fine practicality.

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 scotch yoke assembly, characterized by: the connecting rod (3) which is of an integrated structure and is provided with a sliding space (301) in the middle, a sliding block (5) which is arranged in the sliding space (301), and a crankshaft (4) which is connected with the sliding block (5) in a rotating mode, wherein piston connecting holes (303) are respectively formed in two ends of the connecting rod (3), the sliding block (5) is limited to be capable of sliding in the sliding space (301) in a reciprocating linear mode, and the sliding block (5) is of an integrated structure.

2. A scotch yoke assembly according to claim 1, wherein: a connecting rod pin (404) is arranged on the crankshaft (4), the connecting rod pin (404) penetrates through a connecting rod pin connecting hole (501) in the sliding block (5), and a bushing (6) sleeved outside the connecting rod pin (404) is fixedly arranged in the connecting rod pin connecting hole (501).

3. A scotch yoke assembly according to claim 1, wherein: the two opposite side end surfaces of the sliding block (5) are in sliding butt joint with the two inner walls of the sliding space (301) to limit the reciprocating linear sliding of the sliding block (5), and bearing bushes (7) are respectively arranged on the two opposite side end surfaces of the sliding block (5).

4. A scotch yoke assembly according to claim 3, wherein: the bearing bush (7) is detachably fixed on the end face of the sliding block (5).

5. A Scotch yoke assembly according to any one of claims 1 to 4, wherein: the crankshaft (4) comprises a plurality of sections of main journals which are coaxially arranged, a connecting rod pin (404) of the crankshaft (4) is connected between every two adjacent main journals through a crank part, and the connecting rod pin (404) is fixedly connected with the crank part and the crank part is fixedly connected with the main journals in an inserted mode respectively.

6. A Scotch yoke assembly as claimed in claim 5, wherein: the crank part comprises two opposite cranks (405), the connecting rod pin (404) is positioned between the two cranks (405), and the sliding block (5) penetrated by the connecting rod pin (404) is restrained between the two cranks (405) to form a guide for the reciprocating linear sliding of the sliding block (5).

7. A Scotch yoke assembly as claimed in claim 5, wherein: the crank (405) is provided with a connecting rod pin inserting hole (4051) and a main journal inserting hole (4052), the main journal and the connecting rod pin (404) on two sides of each crank are respectively inserted into the main journal inserting hole (4052) and the connecting rod pin inserting hole (4051) in an interference fit mode, the main journal inserting hole (4052) and the connecting rod pin inserting hole (4051) are partially overlapped, and at least one of the main journal and the connecting rod pin (404) is provided with a avoiding groove.

8. A Scotch yoke assembly as claimed in claim 5, wherein: the connecting line between the centers of the connecting rod pin inserting hole (4051) and the main journal inserting hole (4052) is coincident or approximately coincident with the symmetrical center line P of the crank (405), a planar positioning surface (4053) is arranged on the side portion of the crank (405), and the connecting line between the centers of the main journal inserting hole (4052) and the connecting rod pin inserting hole (4051) is parallel or approximately parallel to the positioning surface (4053).

9. A Scotch yoke assembly as claimed in claim 5, wherein: the connecting rod pin (404) is internally provided with a connecting rod oil duct (4041) with one end communicated with the outer peripheral surface of the middle part of the connecting rod pin (404), the main journal at least one side of the connecting rod pin (404) is internally provided with a main oil duct which can be connected with an external oil supply oil duct, and the main oil duct is connected with the connecting rod oil duct (404) along with the insertion of the connecting rod pin (404) and the main journal on the crank (405).

10. A method of assembling a scotch yoke assembly, comprising: during assembly, firstly press-fitting a crank (405) in a crankshaft (4) on one side of a connecting rod pin (404), enabling one end of the connecting rod pin (404) to be flush with the end face of the crank (405) on the side, then sleeving a sliding block (5) on the connecting rod pin (404), then assembling a connecting rod (3), and then press-fitting the crank (405) on the other side of the connecting rod pin (404);

or, the assembling method is that when assembling, firstly, the crank (405) in the crank shaft (4) positioned at one side of the connecting rod pin (404) is placed on the supporting table, then the sliding block (5) and the connecting rod (3) are assembled, the assembled connecting rod (3) and the assembled sliding block (5) are placed on the end surface of the crank (405) at the side, then, the crank (405) at the other side is placed on the connecting rod (3) and the sliding block (5), and then the connecting rod pin (404) is pressed in.