A multi-stage variable connecting rod

Abstract

This invention discloses a multi-stage variable connecting rod, relating to the field of engine technology. The variable connecting rod includes a connecting rod body and an eccentric rocker arm. Two pistons, A-side and B-side, are connected to each other via connecting members on opposite sides of the eccentric rocker arm. At least one adjustable piston is connected in series on the side of at least one piston facing away from the eccentric rocker arm. Each piston's side facing away from the eccentric rocker arm forms a controlled oil chamber. A hydraulic control system controls the high and low pressure states of each controlled oil chamber, ensuring that one of the A-side and B-side controlled oil chambers is in a high-pressure state while the other is in a low-pressure state. By adjusting the position of the low-pressure chamber and the position of the first high-pressure chamber among the remaining controlled oil chambers on that side, multi-stage variable length of the connecting rod is achieved. This invention has a compact structure, wide engine adaptability, and overcomes the limitation of existing technologies that can only achieve two-stage compression ratio adjustment, significantly improving the flexibility of compression ratio adjustment.

Description

Technical Field

[0001] This invention belongs to the field of engine technology, and specifically relates to a multi-stage variable link for a variable compression ratio mechanism. Background Technology

[0002] Faced with increasingly serious energy security, environmental pollution, and global climate issues, improving engine efficiency and reducing pollutant and greenhouse gas emissions are urgently needed while ensuring long-term engine reliability and environmental adaptability. Regardless of fuel type and operating conditions, the compression ratio has a significant impact on engine mechanical and thermal loads, as well as its combustion and emission performance. The optimal compression ratio required by an engine varies significantly under different operating conditions, especially for high-performance engines with a wide operating range, where it is difficult to simultaneously meet the compression ratio requirements of both high and low operating conditions. Therefore, the development of variable compression ratio mechanisms is crucial for broadening the engine's operating range and improving engine performance across the entire operating range.

[0003] Currently, major domestic and international automotive companies and research institutions have proposed various variable compression ratio solutions. Based on the different methods of achieving variable compression ratio, variable compression ratio mechanisms are mainly classified into several types, including multi-link type, movable cylinder head type, eccentric connecting rod big end type, eccentric connecting rod small end type, variable piston height type, and eccentric crankshaft bearing type. The multi-link type, represented by Nissan and MCE-5, while achieving continuously adjustable compression ratios, significantly increases engine dimensions and is difficult to apply to V-type engines. Saab's movable cylinder head type achieves continuously adjustable compression ratios by adjusting the angle between the upper and lower engine block components, but faces multiple challenges such as difficulties in engine accessory placement and sealing, and deterioration in overall engine rigidity and NVH performance. The eccentric connecting rod big end type, represented by Gomecsys, adds an eccentric sleeve between the connecting rod big end and the crankpin, adjusting the compression ratio by regulating the phase of the eccentric sleeve relative to the crankshaft. While this solution broadens the range of engine models it can be applied to, it faces multiple challenges, including a significant increase in engine axial dimensions and the need to improve the durability of the eccentric sleeve and gear system. The eccentric connecting rod small-end solution, developed by FEV, adds an eccentric sleeve and hydraulic locking mechanism between the connecting rod small end and the piston pin. This solution has high integration but can only achieve two-stage variable compression ratios. The piston height variable solution, designed by Honda, achieves two-stage variable compression ratios by controlling the distance between the inner and outer pistons, but requires solutions to sealing and component reliability issues. WinGD integrates a hydraulic actuator within the crosshead pin, changing the relative piston height by controlling the oil volume in the hydraulic chamber below the piston rod. This solution places extremely high demands on the sealing, durability, and responsiveness of the hydraulic actuator and is only suitable for low-speed engines. The eccentric crankshaft bearing solution adds an eccentric bearing assembly between the crankshaft main journal and the engine block mounting hole. By controlling the phase of this assembly, the position of the crankshaft relative to the engine block can be changed, and the compression ratio can be continuously adjusted. However, the reliable locking problem of this assembly needs to be solved, and this solution is only suitable for inline engines.

[0004] In summary, variable compression ratio technology is of great significance for achieving efficient and stable combustion, clean and low-carbon emissions, and long-term reliable operation of engines. However, existing variable compression ratio solutions all have their own problems that need to be solved. Therefore, how to provide a new type of variable compression ratio mechanism that balances multiple objectives such as flexibility in compression ratio adjustment, compact structure, operational reliability, and engine applicability, in order to broaden the engine's operating range, improve its operational reliability and environmental adaptability, and enhance its combustion and emission performance, has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a multi-stage variable connecting rod. While retaining the advantages of the compact structure and wide adaptability of the eccentric connecting rod small-end type scheme, this invention breaks through the limitation of the prior art that can only achieve two-stage variable compression ratio, and realizes multi-stage variable compression ratio, thereby broadening the engine operating range and further improving the engine's operating reliability, environmental adaptability and combustion and emission performance in the entire operating range.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-stage variable linkage includes a linkage body and an eccentric rocker arm mounted on the linkage body. The outer circle of the eccentric rocker arm is rotatably connected to a through hole in the linkage body. The inner hole of the eccentric rocker arm is connected to a piston pin or a crank pin. The axis of the outer circle of the eccentric rocker arm is parallel to but not collinear with the axis of the inner hole of the eccentric rocker arm. A connecting member on side A and a connecting member on side B are respectively connected to both sides of the eccentric rocker arm. The other end of the connecting member on side A is connected to a first piston on side A, and the other end of the connecting member on side B is connected to a first piston on side B. A series of connecting members are arranged on the side of the first piston on side A and / or the first piston on side B away from the eccentric rocker arm. One less adjustable plunger; wherein, the total number of plungers on side A is M, and each plunger is arranged in series with its effective stroke decreasing sequentially in the direction away from the eccentric rocker arm. The side of each plunger on side A away from the eccentric rocker arm forms the corresponding controlled oil chamber A1...AM; the total number of plungers on side B is N, and each plunger is arranged in series with its effective stroke decreasing sequentially in the direction away from the eccentric rocker arm. The side of each plunger on side B away from the eccentric rocker arm forms the corresponding controlled oil chamber B1...BN; one of M and N is at least 2, and the other is at least 1; by controlling the hydraulic state of each controlled oil chamber, different effective connecting rod lengths are obtained.

[0007] Furthermore, the eccentric swing arm can be a circumferentially split eccentric swing arm, a radially split eccentric swing arm, or an integral eccentric swing arm. When a circumferentially split eccentric swing arm is used, the eccentric swing arm includes an eccentric sleeve and a swing arm. The corresponding part of the connecting rod body adopts a hollow structure along the axial direction, and the swing arm is inserted into the hollow structure of the connecting rod body. Alternatively, the swing arm itself is a swing arm with a hollow structure along the axial direction, and the connecting rod body is inserted into the hollow structure of the swing arm. After the swing arm and connecting rod body are inserted, the inner hole of the swing arm is aligned with the through hole of the connecting rod body, and the eccentric sleeve is fitted into the inner hole of the swing arm and the through hole of the connecting rod body, so that the eccentric sleeve swings synchronously with the swing arm and the outer circle of the eccentric sleeve is located within the through hole of the connecting rod body, thereby limiting the relative rotation of the eccentric swing arm and the connecting rod body. When a radially split eccentric swing arm is used, the eccentric swing arm includes an eccentric swing arm body one and an eccentric swing arm body two, which are fixedly connected to form the outer circle, inner hole, and swing arm portion of the eccentric swing arm; the connecting rod body also adopts a radially split structure, and the connecting rod body includes a connecting rod body and an end cap, which are fixedly connected to form the through hole portion of the connecting rod body; the corresponding parts of the connecting rod body and the end cap both adopt a hollow structure along the axial direction. After the eccentric swing arm body one and the eccentric swing arm body two are fixedly connected, the eccentric... The swing arm portion of the swing arm is inserted into the hollow structure of the connecting rod body, such that the outer circle of the eccentric swing arm is located within the through hole, and the relative rotation between the eccentric swing arm and the connecting rod body is limited by the end cap; or, the swing arm portion of the eccentric swing arm adopts a hollow structure along the axial direction, after the first eccentric swing arm body and the second eccentric swing arm body are fixedly connected, the connecting rod body is inserted into the hollow structure of the swing arm portion, such that the outer circle of the eccentric swing arm is located within the through hole, and the relative rotation between the eccentric swing arm and the connecting rod body is limited by the end cap. When an integrated eccentric swing arm is used, the connecting rod body adopts a radially split structure. The connecting rod body includes a connecting rod body and an end cap, which are fixedly connected to form a through hole portion of the connecting rod body. The corresponding portions of the connecting rod body and the end cap both adopt a hollow structure along the axial direction. The swing arm portion of the eccentric swing arm is inserted into the hollow structure of the connecting rod body, and the outer circle of the eccentric swing arm is located within the through hole. The end cap limits the relative rotation between the eccentric swing arm and the connecting rod body. Alternatively, the swing arm portion of the eccentric swing arm adopts a hollow structure along the axial direction. The connecting rod body is inserted into the hollow structure of the swing arm portion, and the outer circle of the eccentric swing arm is located within the through hole. The end cap limits the relative rotation between the eccentric swing arm and the connecting rod body.

[0008] Furthermore, it also includes a hydraulic control system, which includes a check valve and a controlled valve; the hydraulic control system includes a primary oil supply circuit that supplies oil unidirectionally to controlled oil chamber A1 and controlled oil chamber B1 (only inflow, no outflow) from the supply end; a secondary oil supply circuit that supplies oil unidirectionally to each adjustable plunger from the supply end and / or controlled oil chamber A1 and / or controlled oil chamber B1 (only inflow, no outflow); and a primary drain circuit connecting each controlled oil chamber to the supply end or the drain end; the check valve is installed on the oil supply circuit to achieve unidirectional oil supply. The controlled valve is used to control the on / off state of each oil circuit; the hydraulic control system controls the working state of the controlled valve, and is used to control the high and low pressure states of each controlled oil chamber: the high pressure state refers to the controlled oil chamber being in a unidirectional oil supply state where hydraulic oil only enters and does not exit, and the corresponding oil inlet circuit of the controlled oil chamber is connected and its drain circuit is disconnected; the low pressure state refers to the state where the controlled oil chamber is connected to the oil supply end or the oil drain end, and the corresponding oil inlet circuit and drain circuit of the controlled oil chamber are both connected, or the corresponding oil inlet circuit of the controlled oil chamber is disconnected and its drain circuit is connected; The hydraulic control system is used to ensure that one of the controlled oil chambers A1 and B1 is in a high-pressure state and the other is in a low-pressure state. Different effective link lengths are obtained by controlling the position of the low-pressure oil chamber and the position of the first high-pressure oil chamber among the remaining controlled oil chambers on that side: When controlled oil chamber A1 is in a high-pressure state, B1 is in a low-pressure state; the effective link length is determined by controlling the position of the first high-pressure controlled oil chamber among B2…BN, while the remaining controlled oil chambers are allowed to be in either a high-pressure or low-pressure state; When controlled oil chamber B1 is in a high-pressure state, A1 is in a low-pressure state; the effective link length is determined by controlling the position of the first high-pressure controlled oil chamber among A2…AM, while the remaining controlled oil chambers are allowed to be in either a high-pressure or low-pressure state. The hydraulic control system controls the controlled valves according to the engine operating conditions, ensuring that the high and low pressure states of each controlled oil chamber are at the target high and low pressure states corresponding to the target effective link length.

[0009] Furthermore, a mating structure is formed between the upper end of the adjustable plunger and its mounting hole to obtain the oil drain chamber of the adjustable plunger; the hydraulic control system also includes an oil circuit connecting the oil drain chamber to the oil supply end or to the oil drain end.

[0010] Furthermore, at least one of the adjustable plungers has a controllable drain port on the side wall of its drain chamber: when the adjustable plunger is at its upper limit position, the controllable drain port is blocked by the adjustable plunger, and the controllable drain port is not connected to the drain chamber of the adjustable plunger; when the adjustable plunger is not at its upper limit position, the controllable drain port is not blocked by the adjustable plunger, and the controllable drain port is connected to the drain chamber of the adjustable plunger. The hydraulic control system also includes at least one secondary drain oil circuit for the controlled oil chambers A1 and / or B1; the secondary drain oil circuit is an oil circuit that connects the controlled oil chambers to the oil supply end or to the oil drain end through a set of valve ports of the controlled valve and the drain chamber of at least one adjustable plunger with a controllable drain port: when the number of adjustable plungers involved in the oil circuit is more than one, the drain chambers of the corresponding adjustable plungers are connected in series, and at most one of the controlled oil chambers of each adjustable plunger is in a high-pressure state. The on / off state of the secondary drain oil circuit is determined by the operating state of the controlled valve and the positions of the corresponding adjustable plungers: when it is necessary for all the controlled oil chambers of the adjustable plungers in the circuit to switch to the low-pressure state, the hydraulic control system also controls the corresponding valve port of the controlled valve to open, so that the oil circuit is in the off state. When it is necessary for the controlled oil chamber of any one of the adjustable plungers in the circuit to switch from the low-pressure state to the high-pressure state, the hydraulic control system controls the corresponding valve port of the controlled valve to open, so that the on / off state of the oil circuit is determined by the positions of the corresponding adjustable plungers: during the switching process, when the adjustable plunger has not reached its upper limit position, the oil circuit is in the open state; when the adjustable plunger reaches its upper limit position, the oil circuit is in the off state.

[0011] Furthermore, the secondary oil drain circuit of the controlled oil chamber A1 or B1 includes an oil drain chamber with an adjustable plunger having a controllable oil drain port on the opposite side of the controlled oil chamber.

[0012] Furthermore, a controllable oil drain port is provided on the oil drain chamber sidewall of the adjustable plunger on the side with the smaller plunger diameter between the No. 1 plunger on side A and the No. 1 plunger on side B.

[0013] Furthermore, the hydraulic control system also adds a three-stage drain circuit for the controlled oil chambers A1 and / or B1; the three-stage drain circuit is an oil circuit connecting the aforementioned controlled oil chambers to the oil supply end or to the drain end through controlled valves. The hydraulic control system also has a three-stage drain mode. When it is necessary to switch the controlled oil chamber of at least one adjustable plunger from a low-pressure state to a high-pressure state, the system determines whether to activate the three-stage drain mode based on the effective length of the connecting rod before switching and the effective length of the target connecting rod: when the three-stage drain mode needs to be activated, during the switching process, the hydraulic control system controls the corresponding controlled valve to switch the oil circuit to the connected state; after all the adjustable plungers reach their upper limits, the three-stage drain mode is closed, and the hydraulic control system controls the corresponding controlled valve to switch the oil circuit to the disconnected state. When the three-stage drain mode does not need to be activated, the hydraulic control system controls the corresponding controlled valve to keep the oil circuit in the disconnected state.

[0014] Furthermore, the hydraulic control system also includes a reciprocating drain mode. When it is necessary to switch the controlled oil chamber of at least one adjustable plunger from a low-pressure state to a high-pressure state, the system determines whether to activate the reciprocating drain mode based on the effective length of the connecting rod before switching and the effective length of the target connecting rod. When the reciprocating drain mode needs to be activated, it is activated during the switching process, and the hydraulic control system also controls the corresponding controlled valve to repeatedly switch the high and low pressure states of controlled oil chambers A1 and B1. After all the adjustable plungers reach their upper limits, the reciprocating drain mode is deactivated, and the hydraulic control system controls the corresponding controlled valve to switch the high and low pressure states of controlled oil chambers A1 and B1 to the target high and low pressure states. When the reciprocating drain mode does not need to be activated, the hydraulic control system controls the corresponding controlled valve to switch the high and low pressure states of controlled oil chambers A1 and B1 to the target high and low pressure states.

[0015] Furthermore, the axis of the controlled valve core is parallel or perpendicular to the crankshaft axis, and a valve core positioning and limiting mechanism is provided on the controlled valve.

[0016] Furthermore, the plunger is a composite plunger; the composite plunger includes one central plunger and at least one hollow plunger; the number of hollow plungers is L, namely hollow plunger No. 1, hollow plunger No. 2...L hollow plunger, where L is at least 1; the central plunger and each of the hollow plungers are arranged coaxially in a nested manner, and in any two adjacent plungers, the plunger located on the radially outer side forms an axial limit on the plunger located on the radially inner side to define the upper limit of the stroke of the inner plunger relative to the outer plunger; the central plunger and each hollow plunger form a controlled oil chamber C0, C1, C2...CL on the side away from the eccentric rocker arm; the controlled oil chambers C0, C1, C2...CL-1 are the control oil chambers for the effective length of the composite plunger, and different effective plunger lengths are obtained by controlling the hydraulic state of the controlled oil chambers C0, C1, C2...CL-1; the controlled oil chamber CL is the controlled oil chamber of the composite plunger.

[0017] The beneficial effects of this invention are as follows: 1. Compared with multi-link and eccentric crankshaft bearing solutions, this invention has the advantages of wide applicability to engine models, convenient modification, compact structure, low cost, and convenient control: This invention can not only adapt to all engine models, but also only requires the replacement of the connecting rod, without the need for major modifications to the engine or an increase in the engine's external dimensions. Furthermore, the parts processing and assembly technology is mature, and the switching of the controlled valve is relatively simple, without increasing engine cost or control difficulty.

[0018] 2. Compared with the existing eccentric connecting rod small end type solution, the present invention not only has the advantages of the existing solution, but also overcomes the disadvantage of low flexibility of the existing technology in terms of variable compression ratio, realizes multi-stage variable compression ratio, further expands the engine's operating range and improves the engine's operating reliability, environmental adaptability and combustion and emission performance across the entire operating range. Attached Figure Description

[0019] Figure 1 This is a structural diagram of a four-stage variable linkage.

[0020] Figure 2 This is a simplified diagram of the oil circuit layout for one type of four-stage variable linkage with a controllable drain port on one side.

[0021] Figure 3 Based on Figure 2 The stroke curves of each plunger and the position curve of the controlled valve core are shown in the diagram.

[0022] Figure 4 This is a simplified diagram of the oil circuit layout for one type of four-stage variable linkage with a reciprocating oil discharge mode.

[0023] Figure 5 Based on Figure 4The stroke curves of each plunger and the position curve of the controlled valve core are shown in the diagram.

[0024] Figure 6 The piston stroke curves and controlled valve spool position curves are for one of the oil circuit layout schemes with a three-stage oil drain mode based on a four-stage variable linkage.

[0025] Figure 7 This is a simplified diagram of the hydraulic circuit layout for one type of three-stage variable linkage with a three-position five-way valve.

[0026] Figure 8 This is a cross-sectional view of a six-stage variable linkage.

[0027] Figure 9 This is a simplified diagram of the oil circuit layout for one type of six-stage variable linkage with a reciprocating oil discharge mode.

[0028] Figure 10 This is a simplified diagram of the oil circuit layout for one type of six-stage variable linkage with a controllable drain port on one side.

[0029] Figure 11 This is a schematic diagram of the first structure of the No. 1 controlled valve.

[0030] Figure 12 This is a schematic diagram of the second structure of the No. 1 controlled valve.

[0031] Figure 13 This is a schematic diagram of the first structure of the second controlled valve.

[0032] Figure 14 This is a schematic diagram of the second structure of the second controlled valve.

[0033] Figure 15 This is a schematic diagram of one of the structures of the No. 3 controlled valve.

[0034] Figure 16 This is a schematic diagram of one of the structures of the No. 5 controlled valve.

[0035] Figure 17 This is a schematic diagram of the first structure of the No. 6 controlled valve.

[0036] Figure 18 This is a schematic diagram of the second structure of the No. 6 controlled valve.

[0037] Figure 19 This is a schematic diagram of one of the structures of the No. 7 controlled valve.

[0038] Figure 20 This is a schematic diagram of a combined plunger with a hollow plunger.

[0039] Figure 21 This is a schematic diagram of a combined plunger with two hollow plungers.

[0040] In the diagram: 1. Swing arm; 2. Eccentric sleeve; 2HJ. Spline; 2W. Outer circle; 2N. Inner hole; 3. Connecting rod body; O1. Inner hole axis; O2. Outer circle axis; O3. Lower circle axis; Q1. Bushing No. 1; Q2. Bushing No. 2; GA. Connecting rod on side A; GB. Connecting rod on side B; ZA1. Piston No. 1 on side A; ZB1. Piston No. 1 on side B; ZA2. Piston No. 2 on side A; ZB2. Piston No. 2 on side B; ZA3. Piston No. 3 on side A; ZB3. Piston No. 3 on side B; ZC0. Center piston; ZC1. Hollow piston No. 1; ZC2. Hollow piston No. 2; DKA. Block on side A; DKB. Block on side B; DKA2. Block No. 2 on side A; DKB2. Block No. 2 on side B; DKC. Connecting rod block; DKC 1. No. 1 plug; DKC2. No. 2 plug; HA2. No. 2 plunger sleeve on side A; HB2. No. 2 plunger sleeve on side B; HA3. No. 3 plunger sleeve on side A; HB3. No. 3 plunger sleeve on side B; A1. No. 1 oil chamber on side A; B1. No. 1 oil chamber on side B; A2. No. 2 oil chamber on side A; B2. No. 2 oil chamber on side B; A3. No. 3 oil chamber on side A; B3. No. 3 oil chamber on side B; C0. No. 0 oil chamber; C1. No. 1 oil chamber; C2. No. 2 oil chamber; A2T. No. 2 drain chamber on side A; B2T. No. 2 drain chamber on side B; A3T. No. 3 drain chamber on side A; B3T. No. 3 drain chamber on side B; C0T. No. 0 drain chamber; C1T. No. 1 drain chamber; C2T. No. 2 drain chamber; B2X1. No. 2 first drain port on side B; B2X2. Side 2 No. 2 oil drain port; B3X1, B side 3 No. 1 oil drain port; B3X2, B side 3 No. 2 oil drain port; C0X1, No. 0 No. 1 oil drain port; C0X2, No. 0 No. 2 oil drain port; C1X1, No. 1 No. 1 oil drain port; C1X2, No. 1 No. 2 oil drain port; C2X1, No. 2 No. 1 oil drain port; C2X2, No. 2 No. 2 oil drain port; D1, No. 1 check valve; DA1, A side No. 1 check valve; DB1, B side No. 1 check valve; DA2, A side No. 2 check valve; DB2, B side No. 2 check valve; FK1, No. 1 valve hole; FK2, No. 2 valve hole; F1, No. 1 controlled valve; F2, No. 2 controlled valve; F3, No. 3 controlled valve; F4, No. 4 controlled valve; F5, No. 5 controlled valve; F6, No. 6 controlled valve; F7 1. Controlled valve No. 7; X11. Valve port 1; X12. Valve port 1; X13. Valve port 1; X21. Valve port 2; X22. Valve port 2; X23. Valve port 2; X24. Valve port 2; X25. Valve port 2; X31. Valve port 3; X32. Valve port 3; X33. Valve port 3; X34. Valve port 3; X41. Valve port 4; X42. Valve port 4; X43. Valve port 4; X51. Valve port 5; X52. Valve port 5; X53. Valve port 5; X54. Valve port 5; X55. Valve port 5; X61. Valve port 6; X62. Valve port 6.X63, No. 6 third valve port; X64, No. 6 fourth valve port; X71, No. 7 first valve port; X72, No. 7 second valve port; X73, No. 7 third valve port; X74, No. 7 fourth valve port; X75, No. 7 fifth valve port; X76, No. 7 sixth valve port; F1D, No. 1 limit block; F2D, No. 2 limit block; F3D, No. 3 limit block; F5D, No. 5 limit block; F6D, No. 6 limit block; F7D, No. 7 limit block; F1X, No. 1 valve core; F2X, No. 2 valve core; F3X, No. 3 valve core; F4X, No. 4 valve core; F5X, No. 5 valve core; F6X, No. 6 valve core; F7X, No. 7 valve core; K, connecting hole; XWC, limit groove; P, oil supply end; T, oil drain end. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings. Terms such as "center," "upper," "lower," "inner," "outer," "horizontal," "vertical," "high," "low," and "one side" are used only based on the orientation or positional relationship shown in the drawings; terms such as "first," "second," "number one," and "number two" are used only for descriptive purposes; furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly, for example, as fixed connection, detachable connection, or integral connection; as mechanical connection, electrical connection, or hydraulic connection; as direct connection, indirect connection through an intermediate medium, or connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] Example 1: This embodiment illustrates the structure and working principle of the four-stage variable linkage by taking the example of adding an adjustable plunger below each of the first plunger ZA1 on side A and the first plunger ZB1 on side B. All embodiments given in this invention use the case where the plunger diameter of the first plunger ZA1 on side A is larger than that of the first plunger ZB1 on side B as an example. Figure 1 This is a structural diagram of a four-stage variable linkage, in which... Figure 1 (a) and Figure 1 (b) are the exploded view and assembly view of the connecting rod, respectively. Figure 1 (c) is a cross-sectional view of the connecting rod at its second length. For clarity, the connecting rod body is cut open in the assembly drawing; the cross-sectional view does not include section lines on the connecting rod body. Figure 1As can be seen, in this embodiment, the variable connecting rod includes a connecting rod body 3 and an eccentric swing arm disposed on the connecting rod body 3. The eccentric swing arm is a circumferentially split eccentric swing arm, consisting of a swing arm 1 and an eccentric sleeve 2. The corresponding part of the connecting rod body 3 adopts a hollow structure along the axial direction. The installation process is as follows: first, the second plunger ZA2 on side A and the second plunger ZB2 on side B are installed onto the connecting rod body 3 respectively, and then the second plug DKA2 on side A and the second plug DKB2 on side B are installed onto the connecting rod body 3 respectively, thereby forming a connecting rod assembly. Next, both sides of the swing arm 1 are connected to the connecting rod GA on side A and the connecting rod GB on side B respectively, the other side of the connecting rod GA on side A is connected to the first plunger ZA1 on side A, and the other side of the connecting rod GB on side B is connected to the first plunger ZB1 on side B, thereby forming a swing arm assembly. Then, the first plunger ZA1 on side A and the first plunger ZB1 on side B are installed onto the connecting rod body 3, respectively. The rocker arm 1 is inserted into the hollow structure of the connecting rod body 3, and the internal spline hole on the rocker arm 1 is aligned with the through hole on the connecting rod body 3. The eccentric sleeve 2 is fitted into the internal spline hole of the rocker arm 1 and the through hole of the connecting rod body 3, and the rocker arm 1 and the eccentric sleeve 2 rotate synchronously by means of the spline. Finally, the first bushing Q1 and the second bushing Q2 are installed between the through hole on the connecting rod body 3 and the outer circle 2W of the eccentric sleeve 2, thereby connecting the eccentric sleeve 2 and the connecting rod body 3 and allowing them to rotate relative to each other, thus realizing the rotatable connection between the eccentric rocker arm and the connecting rod body 3. After the connecting rod assembly is fully installed, the piston pin is installed in the inner hole 2N of the eccentric sleeve 2, thereby connecting the connecting rod assembly and the piston. The outer circular axis O2 of the eccentric sleeve 2 is parallel to but not collinear with its inner hole axis O1. Therefore, by swinging the eccentric rocker arm relative to the connecting rod body 3, the distance between the piston pin axis (determined by the inner hole axis O1 of the eccentric sleeve 2) and the lower circular axis O3 of the connecting rod body 3 is changed accordingly, thereby obtaining different effective connecting rod lengths (referred to as connecting rod lengths).

[0043] The specific structure of the eccentric rocker arm in this invention needs to be determined comprehensively based on factors such as the connection object (piston pin or crank pin) to the inner hole of the eccentric rocker arm, as well as the structure and dimensions of related engine components. When the connection object is a piston pin or a split crank pin, a circumferential split or one-piece eccentric rocker arm is preferred. When the connection object is a conventional crank pin, a radial split eccentric rocker arm is preferred. To improve the stress, lubrication, and friction and wear characteristics between the eccentric rocker arm and the connecting rod, it is preferable that one of the eccentric rocker arm or connecting rod has a hollow structure along the axial direction, and the other is inserted into the hollow structure.

[0044] This embodiment presents one structure of a circumferentially split eccentric swing arm. In this split eccentric swing arm, the swing arm 1 is a one-piece structure. To ensure the feasibility of assembling and disassembling the swing arm 1 and eccentric sleeve 2 with the connecting rod 3, and to ensure good stress, lubrication, and friction and wear characteristics, the corresponding part of the connecting rod 3 is a hollow structure along the axial direction, such as... Figure 1As shown, the rocker arm 1 is inserted into the hollow structure of the connecting rod body 3. A circumferentially split eccentric rocker arm can also be a rocker arm with a hollow structure. Specifically, the rocker arm can be integral or split. In short, the rocker arm has a hollow structure along the axial direction, and the connecting rod body is inserted into the hollow structure of the rocker arm. Furthermore, for the integral eccentric rocker arm design, the corresponding part of the connecting rod body preferably has a radially split structure. Specifically, the connecting rod body adopts a structure of connecting rod body and end cap, thereby ensuring the feasibility of disassembling and assembling the integral eccentric rocker arm and the split connecting rod body. For engines using conventional crankshafts, when the connection object of the eccentric rocker arm is the crank pin, it is obviously necessary to use a radially split eccentric rocker arm. That is, the eccentric rocker arm is divided into two parts to ensure the feasibility of disassembling and assembling the eccentric rocker arm and the crank pin and to achieve a rotational connection between the two. These two parts are fixedly connected and form the outer circle, inner hole, and rocker arm part of the eccentric rocker arm. The corresponding connecting rod body also needs to adopt a radially split structure to ensure the feasibility of disassembly and assembly. In summary, the connection relationship between the eccentric rocker arm and the connecting rod body is as follows: the outer circle of the eccentric rocker arm is connected to the through hole on the connecting rod body, and the two rotate relative to each other; the inner hole of the eccentric rocker arm is connected to the piston pin or the crank pin; and the outer circle axis of the eccentric rocker arm is parallel to but not collinear with the inner hole axis. Any connection relationship satisfying the above conditions falls within the protection scope of this invention.

[0045] A controlled oil chamber for each plunger is formed on the side of each plunger away from the eccentric rocker arm. In this embodiment, the controlled oil chamber is formed by... Figure 1As can be seen, a first oil chamber A1 is formed between the lower part of plunger ZA1 on side A and the second plug DKA2 on side A. The upper end of plunger ZA2 on side A is inserted into the through hole of the second plug DKA2 on side A, and a second oil chamber A2 is formed below plunger ZA2 on side A. When the second oil chamber A2 on side A is filled with hydraulic oil, the upper end of plunger ZA2 on side A protrudes from the second plug DKA2 on side A, causing the lower limit of plunger ZA1 on side A to increase. A first oil chamber B1 is formed between the lower part of plunger ZB1 on side B and the second plug DKB2 on side B. The upper end of plunger ZB2 on side B is inserted into the through hole of the second plug DKB2 on side B, and a second oil chamber B2 is formed below plunger ZB2 on side B. When oil chamber B2 on side B is filled with hydraulic oil, the upper end of plunger ZB2 on side B extends from block DKB2 on side B, causing the lower limit of plunger ZB1 on side B to rise. By controlling the high and low pressure states of the four controlled oil chambers, the four-stage adjustment of the connecting rod length can be achieved. Table 1 shows the relationship between the state of each oil chamber and the connecting rod length. It should be noted that the high pressure state in this invention refers to the corresponding controlled oil chamber being in a unidirectional oil supply state where oil only flows in and does not flow out; the low pressure state refers to the corresponding controlled oil chamber being connected to either the oil supply end or the oil drain end; and the "allowable" state means that the controlled oil chamber is allowed to be in either a high pressure state or a low pressure state. The oil supply end preferably comes from the lubrication oil passage of the engine crankshaft. The oil drain end can be connected to the crankcase or oil pan, or it can be connected to the engine lubrication oil passage.

[0046] Table 1. Relationship between the state of each oil chamber and the length of the connecting rod.

[0047] As shown in Table 1, the same variable connecting rod can be arranged in different hydraulic circuits; therefore, the above connecting rod installation instructions do not include the installation of hydraulic circuit-related accessories. Connecting oil chamber A2 on side A and oil chamber B2 on side B simplifies the hydraulic circuit. Table 2 shows the relationship between the simplified oil chamber states and the connecting rod lengths. Figure 1 This simplified approach is adopted.

[0048] Table 2 Relationship between the state of each oil chamber and the length of the connecting rod

[0049] Example 2: To improve the switching responsiveness of the variable linkage, based on Embodiment 1, a further preferred embodiment is proposed: A mating fit is formed between the upper end of the second plunger ZA2 on side A and the through hole of the second plug DKA2 on side A; a second drain chamber A2T on side A is formed between the lower end of the second plug DKA2 on side A and the second plunger ZA2 on side A; a mating fit is formed between the upper end of the second plunger ZB2 on side B and the through hole of the second plug DKB2 on side B; a second drain chamber B2T on side B is formed between the lower end of the second plug DKB2 on side B and the second plunger ZB2 on side B. In this case, at least the aforementioned drain chambers are connected to an oil supply end or an oil passage connected to the drain end.

[0050] It should be noted that a large clearance can be used between the upper end of the No. 2 plunger ZA2 on side A and the through hole of the No. 2 plug DKA2 on side A, and between the upper end of the No. 2 plunger ZB2 on side B and the through hole of the No. 2 plug DKB2 on side B, and correspondingly, there is no oil drain chamber.

[0051] Example 3: For the multi-stage variable linkage, the basic oil circuit layout includes a primary oil supply circuit that supplies oil unidirectionally to oil chamber A1 on side A (only inlet, no outlet) and oil chamber B1 on side B (only inlet, no outlet); a secondary oil supply circuit that supplies oil unidirectionally to the controlled oil chambers of each adjustable plunger from oil supply end P and / or oil chambers A1 on side A and / or oil chamber B1 on side B (only inlet, no outlet); and a primary drain oil circuit connecting each controlled oil chamber to the oil supply end or the drain end. A check valve is installed on the oil supply circuit to achieve unidirectional oil supply, and a controlled valve is used to control the on / off state of each oil circuit.

[0052] The relationship between each controlled oil chamber and the connecting rod length is as follows: By controlling the position of the oil chamber in the low-pressure state in oil chamber A1 on side A and oil chamber B1 on side B, and the position of the first oil chamber in the high-pressure state among the remaining controlled oil chambers on that side (including the remaining controlled oil chambers on that side being in the low-pressure state), different connecting rod lengths can be obtained. From this, a table showing the relationship between the high and low pressure states of each controlled oil chamber and the connecting rod length for different adjustable plunger arrangement schemes can be obtained for the multi-stage variable connecting rod.

[0053] The basic control method is as follows: Based on the above relationship table, the hydraulic control system controls the high and low pressure states of each controlled oil chamber by controlling the working state of the controlled valve, thereby obtaining different connecting rod lengths. Specifically, under high pressure, the oil inlet circuit of the corresponding controlled oil chamber is connected and its oil drain circuit is disconnected; under low pressure, both the oil inlet and oil drain circuits of the corresponding controlled oil chamber are connected, or the oil inlet circuit of the corresponding controlled oil chamber is disconnected and its oil drain circuit is connected.

[0054] The inventors discovered that for most multi-stage variable linkages, when the controlled oil chamber of one or a group of adjustable plungers needs to be switched to a high-pressure state, additional oil drainage is required for oil chamber A1 on side A and / or oil chamber B1 on side B when necessary. The oil inlet or outlet volume of each plunger corresponding to the target linkage length before switching determines whether additional oil drainage is required for oil chamber A and / or oil chamber B1 on side B during the switching process. Once the parameters such as the diameter and stroke of each plunger are determined, it is only necessary to judge based on the length of the target linkage before switching. If any switching process requires additional oil drainage, the following should be further adopted: (1) an oil circuit layout scheme with a controllable drain port combined with a basic control method; (2) a basic oil circuit layout scheme combined with a control method with a reciprocating switching mode; (3) an oil circuit layout scheme with a three-stage drain mode and a corresponding control method; (4) a combination of the above schemes and methods. The secondary fuel supply circuit uses a unidirectional fuel supply scheme with supply end P. If an adjustable plunger is installed on either side A or B, additional oil drainage is required from the first oil chamber on the other side when necessary. This creates a conflict between the number of variable stages and the complexity of the fuel circuit, and the switching response of this scheme is poor. Therefore, the secondary fuel supply circuit preferably uses the first oil chamber A1 on side A and / or the first oil chamber B1 on side B for unidirectional fuel supply.

[0055] In the preferred embodiment of Example 2, additional oil drainage is required for oil chamber A1 on side A when necessary, but additional oil drainage is never required for oil chamber B1 on side B. When additional oil drainage is required for oil chamber A1 on side A, it is easier to facilitate the upward movement of plunger ZA2 on side B compared to plunger ZB2 on side B. Therefore, it is preferable to provide a controllable drain port on the side wall of oil chamber B2T on side B (i.e., preferably on the drain chamber side wall of the adjustable plunger with the smaller plunger diameter between plungers A1 and B1 on side A). The secondary drain oil path of oil chamber A1 on side A adopts a scheme connected to oil chamber B2T on side B (i.e., the secondary drain oil path of oil chamber A1 on side A or oil chamber B1 on side B preferably includes the drain chamber of the adjustable plunger with a controllable drain port on the opposite side of the controlled oil chamber). Figure 2 This is a simplified diagram of the corresponding oil circuit layout. Figure 3 Based on Figure 2 The scheme includes the stroke curves of each plunger and the spool position curve of the controlled valve. Among them, Figure 3 (a) shows the case when switching sequentially from the first, second, third, fourth, and second lengths. Figure 3 (b) shows the case when switching lengths sequentially from the first, fourth, third, second, first, and third. (From...) Figure 2 As can be seen, the oil circuit includes four check valves and two controlled valves. Among them, the first controlled valve, F1, is a two-position three-way valve. Its first state is: the first valve port X11 is blocked, and the second valve port X12 and the third valve port X13 are connected. Figure 3The low position of F1X; the second state is: the second valve port X12 is blocked, and the first valve port X11 and the third valve port X13 are connected, corresponding to Figure 3 The high position of F1X. Controlled valve F2 is a two-position five-way valve. Its first state is: valve port X23 is blocked; valve port X21 is connected to valve port X25; valve port X22 is connected to valve port X24. Figure 3 The low position of F2X; the second state is: valve ports X21, X22, and X25 are all blocked, while valve ports X23 and X24 are connected. Figure 3 The high position of F2X in China.

[0056] The oil circuit connections are as follows: Oil supply terminal P supplies oil unidirectionally to oil chamber A1 on side A through check valve DA1 on side A, and oil supply terminal P supplies oil unidirectionally to oil chamber B1 on side B through check valve DB1 on side B. Oil chamber A1 on side A is connected to the first valve port X11, oil chamber B1 on side B is connected to the second valve port X12, and the third valve port X13 is connected to the drain terminal T. Oil chamber A1 on side A supplies oil unidirectionally to the second valve port X22 on side A through check valve DA2 on side A, oil chamber B1 on side B supplies oil unidirectionally to the second valve port X22 on side B through check valve DB2 on side B, the third valve port X23 is connected to oil supply terminal P, and both oil chambers A2 on side A and B2 on side B are connected to the fourth valve port X24. The specific details regarding the controllable drain ports are as follows: On the side wall of the second drain chamber B2T on side B, there are also a second drain port B2X1 and a second drain port B2X2, both connected to the second drain chamber B2T. The position of the second plunger ZB2 on side B determines whether the first drain port B2X1 is blocked. When the second plunger ZB2 is at its upper limit, it blocks the first drain port B2X1. When the second plunger ZB2 has not yet reached its upper limit, it cannot completely block the first drain port B2X1. Based on this, a two-stage drain circuit is formed in oil chamber A1 on side A. Specifically, oil chamber A1 on side A sequentially passes through valve port X21, valve port X25, drain port B2X1 on side B, oil chamber B2T on side B, and drain port B2X2 on side B, before connecting to the oil supply terminal P. When the controlled valve F2 is in a low position, valve port X21 and valve port X25 are connected, so the connection state of this circuit is determined by the position of plunger ZB2 on side B. When the controlled valve F2 is in a high position, both valve port X21 and valve port X25 are blocked, so the circuit is disconnected. Since it is not necessary to install a controllable drain port on the side wall of oil chamber A2T on side A, it can simply be connected to the oil supply terminal P. By controlling the first controlled valve F1, the high and low pressure states of oil chamber A1 on side A and oil chamber B1 on side B are controlled. By controlling the second controlled valve F2, the high and low pressure states of oil chamber A2 on side A and oil chamber B2 on side B are controlled. Combining these two methods allows for four-stage variable linkage length. Table 3 shows the relationship between the valve core position of each controlled valve and the linkage length, and the corresponding oil chamber states are shown in Table 2.

[0057] Table 3 Relationship between the operating state of the controlled valve and the connecting rod length

[0058] The specific control method and the working process of the variable linkage are as follows: When the engine needs to switch the variable linkage to the first length, the first controlled valve F1 is in a low position and the second controlled valve F2 is in a high position, thereby realizing the intermittent unidirectional oil supply from the oil supply end P to the first oil chamber A1 on side A. The first oil chamber B1 on side B is connected to the oil drain end T. The second oil chambers A2 on side A and B2 on side B are both connected to the oil supply end P. Under the combined action of the engine piston inertial force and gas force, the eccentric rocker arm is always subjected to alternating torque. When the plungers have not reached the target position required by the first length, the alternating torque causes plunger ZA1 on side A to move upward and plunger ZB1 on side B to move downward (and, if necessary, also pushes plunger ZB2 on side B downward), until plunger ZA1 on side A moves upward to its highest upper limit and plunger ZB1 on side B moves downward to its lowest lower limit. Simultaneously, although the hydraulic pressure in oil chamber A1 on side A fluctuates, it is generally high. This hydraulic pressure directly acts on the upper end of plunger ZA2 on side A, causing plunger ZA2 to remain stationary at its lowest lower limit or pushing it downward until it reaches its lowest lower limit and remains stationary. At this point, the connecting rod has been completely switched to the first length.

[0059] When the engine needs to switch the variable linkage to the second length, both controlled valves F1 and F2 are in the low position. When plunger ZB2 on side B has not yet reached its upper limit, the secondary drain circuit of oil chamber A1 on side A is connected. Under the action of alternating torque, oil chambers A1 on side A and B1 on side B intermittently supply oil unidirectionally to oil chambers A2 and B2 on side A and B respectively. Simultaneously, additional oil draining from oil chamber A1 on side A is performed when necessary, ultimately causing plungers ZA2 on side A and ZB2 on side B to rise to their respective upper limits. When plunger ZB2 on side B reaches its upper limit, the secondary drain circuit of oil chamber A1 on side A is disconnected, and oil chamber A1 on side A is completely in an intermittent unidirectional oil supply state. The alternating torque eventually causes plunger ZA1 on side A to reach its second-highest upper limit and plunger ZB1 on side B to reach its second-lowest lower limit (i.e., the position where plunger ZB1 on side B contacts the upper end of plunger ZB2 on side B). At this point, the connecting rod has been completely switched to the second length.

[0060] When the engine needs to switch the variable linkage to the third length, the first controlled valve F1 is in the high position and the second controlled valve F2 is in the low position. Oil chamber A1 on side A is connected to the drain end T, and the supply end P intermittently supplies oil unidirectionally to oil chamber B1 on side B. Oil chambers A1 and B1 intermittently supply oil unidirectionally to oil chambers A2 and B2 on side A and B, respectively. Simultaneously, when plunger ZB2 on side B has not yet reached its upper limit, oil chamber A1 on side A is connected to both the drain end T and the supply end P; when plunger ZB2 on side B reaches its upper limit, oil chamber A1 on side A is connected to the drain end T. Under the action of alternating torque, both pistons ZA2 on side A and ZB2 on side B remain at their respective upper limits or move upwards to their respective upper limits. Piston ZA1 on side A moves to its second-lower limit (i.e., the position where the upper ends of piston ZA1 and piston ZA2 on side A are in contact) and piston ZB1 on side B moves to its second-highest limit. At this point, the connecting rod has been completely switched to the third length.

[0061] When the engine needs to switch the variable linkage to the fourth length, both controlled valves F1 and F2 are in the high position. The oil supply terminal P intermittently supplies oil unidirectionally to oil chamber B1 on side B. Oil chamber A1 on side A is connected to the drain terminal T, and oil chambers A2 on side A and B2 on side B are both connected to the oil supply terminal P. Under the action of alternating torque, plunger ZA1 on side A eventually descends (and, if necessary, pushes plunger ZA2 on side A downwards) until it reaches its lowest limit, while plunger ZB1 on side B ascends to its highest limit. Simultaneously, although the hydraulic pressure in oil chamber B1 on side B fluctuates, it is generally very high. This hydraulic pressure directly acts on the upper end of plunger ZB2 on side B, causing plunger ZB2 to remain stationary at its lowest limit or pushing it downwards to its lowest limit and remain stationary. At this point, the linkage has been completely switched to the fourth length.

[0062] Depend on Figure 3 It is evident that regardless of the required linkage length, controlling the two controlled valves based on the valve core position corresponding to the target linkage length will allow for smooth switching of each plunger to its target position. Furthermore, after switching, each plunger will remain stable in its target position. Therefore, the oil circuit arrangement with controllable drain ports offers the advantage of the simplest control of the controlled valves. It should be noted that the No. 1 third valve port X13, the No. 2 drain chamber A2T on side A, the No. 2 second drain port B2X2 on side B, and the No. 2 third valve port X23 can all be connected to either the supply end P or the drain end T. Similarly, the drain circuit of this invention can be selectively connected to either the supply end P or the drain end T.

[0063] Example 4: Figure 4 This is a simplified diagram of an oil circuit layout with a reciprocating oil draining mode, corresponding to one of the preferred schemes of Example 2. Figure 5 Based on Figure 4 The scheme includes the stroke curves of each plunger and the spool position curve of the controlled valve, as well as the switching sequence of each connecting rod length. Figure 3 Same. By Figure 4 As can be seen, the oil circuit includes three check valves and two controlled valves. Among them, the third controlled valve, F3, is a two-position four-way valve. Its first state is: the first valve port X31 of F3 is connected to the fourth valve port X34 of F3, and the second valve port X32 of F3 is connected to the third valve port X33 of F3. Figure 5 The low position of F3X; the second state is: the first valve port X31 of the third valve is connected to the third valve port X33 of the third valve, and the second valve port X32 of the third valve is connected to the fourth valve port X34 of the third valve, corresponding to Figure 5 The high position of F3X. Controlled valve F4 is a two-position three-way valve. Its first state is: valve port X42 is blocked, and valve port X41 is connected to valve port X43. Figure 5 The low position of F4X; the second state is: the first valve port X41 of the fourth valve is blocked, and the second valve port X42 of the fourth valve is connected to the third valve port X43 of the fourth valve, corresponding to Figure 5 The high position of F4X.

[0064] The oil circuit connections are as follows: Oil chamber A1 on side A is connected to valve port X31 (first valve). Oil chamber B1 on side B is connected to valve port X32 (second valve). The oil supply end P supplies oil unidirectionally to valve port X34 (fourth valve) via check valve D1 (first check valve). Oil chamber A1 on side A supplies oil unidirectionally to valve port X41 (first valve) via check valve DA2 (second check valve). Oil chamber B1 on side B supplies oil unidirectionally to valve port X41 (first valve) via check valve DB2 (second check valve). Oil chambers A2 on side A and B2 on side B are both connected to valve port X43 (third valve). Oil drain chambers A2T on side A, B2T on side B, valve port X33 (third valve), and valve port X42 (second valve) on side B are all connected to the oil supply end P. Controlled valve F3 (number 3) controls the high and low pressure states of oil chamber A1 on side A and oil chamber B1 on side B, while controlled valve F4 (number 4) controls the high and low pressure states of oil chamber A2 on side A and oil chamber B2 on side B. Combining these two controls allows for four-stage variable linkage length. Table 4 shows the relationship between the valve core position of each controlled valve and the linkage length; the corresponding oil chamber states are shown in Table 2.

[0065] Table 4 Relationship between the position of the valve core and the length of the connecting rod of the controlled valve

[0066] The specific control method and the working process of the variable linkage are as follows: When the engine needs to switch the variable linkage to the first length, the third controlled valve F3 is in the low position and the fourth controlled valve F4 is in the high position. This connects the first oil chamber B1 on side B, the second oil chamber A2 on side A, and the second oil chamber B2 on side B to the oil supply end P; the oil supply end P intermittently supplies oil to the first oil chamber A1 on side A in one direction. The alternating torque acting on the eccentric rocker arm eventually causes the linkage to be completely switched to the first length.

[0067] When the engine needs to switch the variable linkage to the second length, the fourth controlled valve F4 is in the low position, and the third controlled valve F3 is controlled according to the linkage length before the switch. When the linkage length before the switch is the third length, the third controlled valve F3 is in the low position. The alternating torque causes the oil supply end P to intermittently supply oil to the first oil chamber A1 on side A, and the first oil chamber B1 on side B to discharge oil to the oil supply end P, eventually causing the linkage to be completely switched to the second length. When the linkage length before the switch is the first or fourth length, it is also necessary to determine whether the reciprocating oil drain mode needs to be activated according to the linkage length before the switch. When the linkage length before the switch is the first length, the reciprocating oil drain mode is activated during the switching process, switching the third controlled valve F3 back and forth (corresponding to...). Figure 5 (F3X is repeatedly changed between low and high positions), using alternating torque to achieve the reciprocating swing of the eccentric rocker arm, which in turn drives the reciprocating movement of plunger ZA1 on side A and plunger ZB1 on side B. This accelerates the rate at which oil chambers A1 on side A and B1 on side B intermittently supply oil to oil chambers A2 on side A and B2 on side B, and achieves additional oil drainage in oil chamber A1 on side A, ultimately enabling plungers ZA2 on side A and ZB2 on side B to move rapidly towards their respective upper limits. When both plungers reach their respective upper limits, the reciprocating drainage mode is closed, i.e., the controlled valve F3 is switched to the low position. The alternating torque ultimately causes the connecting rod to be completely switched to the second length. When the previous length was the fourth length, the reciprocating drainage mode does not need to be activated, and the controlled valve F3 is switched to the low position. The alternating torque causes oil to be discharged from oil chamber B1 on side B to oil supply end P. Oil supply end P intermittently supplies oil to oil chamber A1 on side A in one direction. Oil chamber A1 on side A and oil chamber B1 on side B also intermittently supply oil to oil chamber A2 on side A and oil chamber B2 on side B in one direction, eventually causing the connecting rod to be completely switched to the second length.

[0068] When the engine needs to switch the variable linkage to the third length, the controlled valve F3 (number three) is in the high position and the controlled valve F4 (number four) is in the low position, and the linkage is eventually completely switched to the third length. The difference is: when the previous length was the second length, the alternating torque causes the oil supply end P to intermittently supply oil to oil chamber B1 on side B, and oil chamber A1 on side A to discharge oil to the oil supply end P. When the previous length was the first or fourth length, the alternating torque causes the oil supply end P to intermittently supply oil to oil chamber B1 on side B, and also causes oil chambers A1 on side A and B1 on side B to intermittently supply oil to oil chambers A2 on side A and B2 on side B. Furthermore, when the previous length was the first length, oil chamber A1 on side A discharges oil to the oil supply end P; when the previous length was the fourth length, the oil supply end P also replenishes oil to oil chamber A1 on side A.

[0069] When the engine needs to switch the variable connecting rod to the fourth length, both controlled valves F3 (number 3) and F4 (number 4) are switched to the high position. The alternating torque causes the oil supply end P to intermittently supply oil to oil chamber B1 on side B, while oil chambers A1 (number 1) on side A, A2 (number 2) on side A, and B2 (number 2) on side B all discharge oil to the oil supply end P, ultimately causing the connecting rod to be completely switched to the fourth length.

[0070] Depend on Figure 5 As can be seen, when adopting the oil circuit layout scheme with a reciprocating oil drain mode, regardless of the required connecting rod length, it is only necessary to control the two controlled valves according to the valve core position of the controlled valve corresponding to the target connecting rod length, and to activate the reciprocating oil drain mode when necessary based on the connecting rod length before switching. This ensures smooth switching of each plunger to its target position, and after switching, each plunger can stabilize at its target position. Compared with the scheme with a controllable oil drain port, the oil circuit on the variable connecting rod and the structure of the fourth controlled valve are simpler with this scheme, but the control complexity is increased.

[0071] It should be noted that, regarding the oil circuit layout scheme for controlling the high and low pressure states of oil chamber A1 on side A and oil chamber B1 on side B, Figure 2 The scheme of using the first controlled valve F1 in conjunction with the first check valve DA1 on side A and the first check valve DB1 on side B is similar to... Figure 4 The combination of controlled valve F3 (number 3) and check valve D1 (number 1) is interchangeable. If a reciprocating drain mode is further adopted, then when the reciprocating drain mode needs to be activated, it is necessary to switch between controlled valve F1 (number 1) and controlled valve F3 (number 3).

[0072] Example 5: exist Figure 4Based on the existing design, adding a two-position two-way valve or replacing the third controlled valve with a three-position four-way valve can both achieve a hydraulic circuit layout scheme with a three-stage drain mode for the four-stage variable linkage. Taking the scheme of adding a two-position two-way valve as an example, its hydraulic circuit layout scheme requires adding a three-stage drain oil circuit to the first oil chamber A1 on side A. That is, this oil chamber is connected to the oil supply end or the drain end through a two-position two-way valve, and the on / off state of this oil circuit is controlled by the two-position two-way valve. Figure 6 The diagram shows the plunger stroke curves and controlled valve spool position curves for a scheme with a three-stage oil drain mode. Figure 6 The switching order and Figure 5 (a) is the same. Other switching procedures are the same as... Figure 5 The similarities are very similar, so they will not be repeated.

[0073] The control method is as follows: The two controlled valves are controlled according to the valve core positions of the third and fourth controlled valves corresponding to the target linkage length; except for the switching process from the first length to the second length, all other switching processes and the linkage length holding phase require keeping the two-position two-way valve in the open state (corresponding to...). Figure 6 (Low position of FX). When switching from the first length to the second length, in addition to keeping both the third and fourth controlled valves in the low position, during the switching process, if the second plunger ZA2 on side A and the second plunger ZB2 on side B have not reached their respective upper limits, it is also necessary to activate the three-stage oil drain mode to keep the two-position two-way valve in the connected state (corresponding to...). Figure 6 (At the high position of FX), the three-stage drain circuit is switched to the connected state to achieve additional draining of oil from oil chamber A1 on side A; when both plungers have reached their respective upper limits, the three-stage drain mode is closed, and the two-position two-way valve is controlled to be in the open state, so that the three-stage drain circuit is switched back to the open state. Under the action of alternating torque, the connecting rod is finally completely switched to the second length.

[0074] Depend on Figure 6 As can be seen, when adopting the three-stage drain mode scheme, regardless of the required connecting rod length, it is only necessary to control the three controlled valves according to the valve core position of the controlled valve corresponding to the target connecting rod length, and to activate the three-stage drain mode when necessary based on the connecting rod length before switching. This ensures a smooth switching of each plunger to its target position, and after switching, each plunger can stabilize at its target position. In terms of control complexity, as well as oil circuit and structural complexity, the scheme with the three-stage drain mode falls between the other two schemes mentioned above.

[0075] It should also be noted that a four-stage variable linkage can also be obtained by adding two adjustable plungers to one side (A or B) and not adding any adjustable plungers to the other side. However, based on the relationship between the state of each oil chamber and the length of the linkage, it is easy to see that the scheme with a large difference in the number of plungers on side A and side B requires more complex hydraulic circuits and controlled valves. For example, even with the basic circuit layout, using controlled valve F1 or controlled valve F3 to control the high and low pressure states of oil chamber A1 on side A and oil chamber B1 on side B, a three-position four-way valve is still needed to control the high and low pressure states of oil chamber A2 and oil chamber A3 on side A. From the perspective of simplifying the circuit layout, the four-stage variable linkage is preferably achieved by adding one adjustable plunger to each side (A and B). Similarly, the multi-stage variable linkage is also preferably achieved by minimizing the difference in the number of plungers on side A and side B.

[0076] Example 6: Adding an adjustable plunger to side A or B creates a three-stage variable linkage. Removing the relevant oil passages from oil chambers A2 or B2 in a four-stage variable linkage circuit layout allows for the creation of a three-stage variable linkage. Alternatively, a circuit layout with a three-position multi-way controlled valve can also be used for the three-stage variable linkage. Figure 7 One possible hydraulic circuit layout is presented when using plunger #2 on side A. This hydraulic circuit includes four check valves and one controlled valve. Controlled valve #5, F5, is a three-position five-way valve. The hydraulic circuit connections are as follows: Supply port P supplies oil unidirectionally to oil chamber A1 on side A through check valve #1 (DA1); supply port P also supplies oil unidirectionally to oil chamber B1 on side B through check valve #1 (DB1). Oil chamber A1 on side A supplies oil unidirectionally to valve port X51 on side 5 through check valve #2 (DA2); oil chamber B1 on side B supplies oil unidirectionally to valve port X51 on side 5 through check valve #2 (DB2); oil chamber A1 on side A is connected to valve port X53 on side 5; oil chamber B1 on side B is connected to valve port X52 on side 5; and oil chamber A2 on side A is connected to valve port X55 on side 5. Both the fourth valve port X54 on side 5 and the second drain chamber A2T on side A are connected to the oil supply end P. The high and low pressure states of each oil chamber are controlled by controlling the controlled valve F5 on side 5. Table 5 shows the relationship between the working state of the controlled valve, the state of each oil chamber, and the length of the connecting rod. Since this embodiment does not require additional oil draining from oil chamber A1 on side A or oil chamber B1 on side B during the process of moving the second plunger on side A to its upper limit, this embodiment can achieve smooth switching between the lengths of each connecting rod by adopting the basic oil circuit layout scheme and basic control method.

[0077] Table 5. Relationship between the operating state of the controlled valve, the state of each oil chamber, and the length of the connecting rod.

[0078] Example 7: Considering that the optimal solution for multi-stage variable linkages is the one with the smallest difference in the number of adjustable plungers on sides A and B, the following section focuses on several preferred hydraulic circuit layout schemes for this type of linkage. The first scheme involves using either controlled valve F1 (number one) or controlled valve F3 (number three) to control the high and low pressure states of oil chamber A1 on side A and oil chamber B1 on side B. Based on this, the hydraulic circuit layout is further designed according to the number of variable stages. For an even number of variable stages, the hydraulic circuits for each adjustable plunger can adopt a combined hydraulic circuit layout. For example, a six-stage variable linkage also requires two two-position multi-way valves (such as controlled valve F2 (number two) and controlled valve F4 (number four)) or one three-position multi-way valve (as described later). Figure 9 The sixth controlled valve F6 in the middle Figure 10 Schemes such as the controlled valve F7 (number 7 in the example). For schemes with an odd number of variable stages (2N-1), the relevant oil circuits of the corresponding end adjustable plunger can be removed from the above schemes with an even number of variable stages (2N). For example, removing the relevant oil circuits of plunger No. 3 on side A or side B in the oil circuit of a six-stage variable connecting rod allows it to be used for a five-stage variable connecting rod.

[0079] The second approach is as follows: For variable links with an odd number of variable stages, a three-position multi-way valve can be used to control the high and low pressure states of the controlled oil chambers A1 on side A, B1 on side B, and one of the controlled oil chambers of the adjustable plunger on the side with more adjustable plungers. Other adjustable plungers use the same oil circuit arrangement as described above for variable links with an even number of adjustable plungers. For example, for a variable link where there is one more adjustable plunger on side A than on side B, controlled valve F5 (number 5) can be used to control the high and low pressure states of the controlled oil chambers A1 on side A, B1 on side B, and one of the controlled oil chambers of the adjustable plunger on side A. For a variable link where there is one less adjustable plunger on side A than on side B, the connection relationships of the valve ports of controlled valve F5 need to be modified, and it should be used to control the high and low pressure states of the controlled oil chambers (denoted by BX) of the controlled oil chambers A1 on side A, B1 on side B, and one of the controlled oil chambers of the adjustable plunger on side B. Table 6 shows the relationship between the operating state of one of the selectable controlled valves, the state of each oil chamber, and the connecting rod length. Specifically, valve port X54 (number 5) is connected to the controlled oil chamber of the adjustable plunger selected on side B. The other valve ports are connected to... Figure 7 The same applies. Obviously, this requires the use of a reciprocating switching mode when necessary to ensure that the adjustable plunger selected on side B above reliably operates to its upper limit.

[0080] Table 6. Relationship between the operating state of the controlled valve, the state of each oil chamber, and the length of the connecting rod.

[0081] The above solutions are only a small subset of embodiments of the present invention, including two types of solutions and combinations thereof: one with a single-sided controllable drain port and the other with a reciprocating drain mode. Based on the description of the above solutions, it is easy to obtain an oil circuit arrangement scheme for a multi-stage variable connecting rod with a double-sided controllable drain port, a three-stage drain mode, and a larger difference in the number of adjustable plungers on side A and side B. Considering space limitations, only some preferred oil circuit arrangement schemes for a six-stage variable connecting rod will be given below.

[0082] Example 8: Figure 8 A cross-sectional view of the six-stage variable connecting rod with two adjustable plungers added to both sides A and B. Compared to Embodiment 1, this embodiment uses a plunger sleeve scheme. Specifically, plunger sleeves HA2 (side A), HB2 (side B), HA3 (side A), and HB3 (side B) are respectively installed in the corresponding mounting holes of the connecting rod body 3. Each of these plunger sleeves contains a corresponding plunger ZA2 (side A), ZB2 (side B), ZA3 (side A), and ZB3 (side B) to form a mating pair. A-side plug DKA is used to fix plunger sleeves HA2 and HA3 in the mounting holes of the connecting rod body 3; a B-side plug DKB is used to fix plunger sleeves HB2 and HB3 in the mounting holes of the connecting rod body 3. For variable linkages with a large number of variable stages, using a plunger sleeve design is beneficial for improving the stress and frictional wear characteristics of the various components of the variable linkage, especially when the end adjustable plunger is under high pressure. A controlled oil chamber is formed on the side of each plunger away from the eccentric rocker arm. In this embodiment, oil chamber A1 is formed between the lower part of plunger ZA1 on side A and plunger sleeve HA2 on side A; oil chamber A2 is formed between the lower part of plunger ZA2 on side A and plunger sleeve HA3 on side A; oil chamber A3 is formed below plunger ZA3 on side A; oil chamber B1 is formed between the lower part of plunger ZB1 on side B and plunger sleeve HB2 on side B; oil chamber B2 is formed between the lower part of plunger ZB2 on side B and plunger sleeve HB3 on side B; oil chamber B3 is formed below plunger ZB3 on side B. Six-stage variable link length was achieved by controlling the above six controlled oil chambers. Table 7 shows one simplified relationship between the state of each controlled oil chamber and the link length.

[0083] Further optimization: A pair of fittings are formed between the upper end of plunger ZA2 on side A and the through hole on plunger sleeve HA2 on side A; between the upper end of plunger ZB2 on side B and the through hole on plunger sleeve HB2 on side B; between the upper end of plunger ZA3 on side A and the through hole on plunger sleeve HA3 on side A; and between the upper end of plunger ZB3 on side B and the through hole on plunger sleeve HB3 on side B. A corresponding drain chamber for each adjustable plunger is formed between each adjustable plunger and its corresponding plunger sleeve. In this embodiment, a second drain chamber A2T is formed between the second plunger ZA2 on side A and the second plunger sleeve HA2 on side A; a third drain chamber A3T is formed between the third plunger ZA3 on side A and the third plunger sleeve HA3 on side A; a second drain chamber B2T is formed between the second plunger ZB2 on side B and the second plunger sleeve HB2 on side B; and a third drain chamber B3T is formed between the third plunger ZB3 on side B and the third plunger sleeve HB3 on side B.

[0084] Table 7 Relationship between the state of each oil chamber and the length of the connecting rod

[0085] Example 9: Figure 9 This is a simplified diagram of the hydraulic circuit layout for one type of reciprocating oil discharge mode in a six-stage variable linkage. The hydraulic circuit includes three check valves and two controlled valves. Controlled valve F6 (position 6) is a three-position four-way valve. Its first state is: valve port X61 is blocked, and valve ports X62, X63, and X64 are connected, corresponding to the low position. The second state is: valve ports X61 and X64 are connected, and valve ports X62 and X63 are connected, corresponding to the middle position. The third state is: valve port X62 is blocked, and valve ports X61, X63, and X64 are connected, corresponding to the high position. The hydraulic circuit connections are as follows: the connection status of each valve port of controlled valve F6 is... Figure 4The same applies. Oil chamber A1 on side A supplies oil unidirectionally to valve port X61 (number 6) via check valve DA2 on side A. Oil chamber B1 on side B supplies oil unidirectionally to valve port X61 (number 6) via check valve DB2 on side B. Oil chambers A2 on side A and B2 on side B are both connected to valve port X63 (number 6). Oil chambers A3 on side A and B3 on side B are both connected to valve port X64 (number 6). Valve port X62 (number 6), drain chambers A2T on side A, B2T on side B, drain chambers A3T on side A and B3T on side B are all connected to the oil supply end P. The high and low pressure states of oil chambers A1 on side A and B1 on side B are controlled by controlling valve F3 (control valve number 3). The high and low pressure states of oil chambers A2 on side A and B2 on side B, as well as oil chambers A3 on side A and B3 on side B, are controlled by controlling valve F6 (control valve number 6). Combining these two methods allows for six-stage variable linkage length. Table 8 shows the relationship between the valve core position of each controlled valve and the linkage length, and the corresponding oil chamber states are shown in Table 7. In the third and fourth lengths, oil chambers A3 on side A and B3 on side B are both in an "either / or" state; this embodiment uses a high-pressure state. Regardless of the linkage length to be switched to, simply controlling the two controlled valves according to the valve core position of the controlled valve corresponding to the target linkage length, and combining this with the linkage length before switching to activate the reciprocating oil discharge mode when necessary, ensures smooth switching of each plunger to its target position. After switching, each plunger remains stable at its target position.

[0086] Table 8. Relationship between valve core position and connecting rod length for each controlled valve

[0087] Example 10: Figure 10This is a simplified diagram of the hydraulic circuit layout for one type of six-stage variable linkage with a controllable drain port on one side. The hydraulic circuit includes three check valves and two controlled valves. Among them, the controlled valve F7 (No. 7) is a three-position six-way valve. Its first state is as follows: both valve ports X71 and X72 are blocked; valve ports X73, X74, X75, and X76 are connected, corresponding to the low position. The second state is as follows: valve ports X71 and X76 are connected; valve ports X72 and X75 are connected; valve ports X73 and X74 are connected, corresponding to the middle position. The third state is as follows: valve ports X71 and X76 are connected; valve ports X72 and X74 are connected; valve ports X73 and X75 are connected, corresponding to the high position. This embodiment includes a secondary drain oil circuit for oil chamber A1 on side A. Correspondingly, controllable drain ports are provided on the second drain chamber B2T and the third drain chamber B3T on side B. The details regarding the controllable drain port on the side wall of the second drain chamber B2T and the related connections of the third controlled valve are as follows: Figure 2 The same applies. On the side wall of the third drain chamber B3T on side B, there are also the first drain port B3X1 and the second drain port B3X2, both connected to the third drain chamber B3T. The position of the second plunger ZB2 on side B determines whether the first drain port B2X1 is blocked. The position of the third plunger ZB3 on side B determines whether the first drain port B3X1 is blocked. The connection relationship of the remaining oil circuits is as follows: the first oil chamber A1 on side A is connected to the first valve port X71 of the seventh valve; the first oil chamber A1 on side A supplies oil unidirectionally to the second valve port X72 of the seventh valve through the second check valve DA2 on side A; the first oil chamber B1 on side B supplies oil unidirectionally to the second valve port X72 of the seventh valve through the second check valve DB2 on side B; the second oil chamber A2 on side A and the second oil chamber B2 on side B are both connected to the fourth valve port X74 of the seventh valve; the third oil chamber on side A... Both cavity A3 and oil cavity B3 on side B are connected to valve port X75 on side 7. Valve port X76 on side 7 is connected to oil drain port B2X1 on side B. Oil drain port B2X2 on side B is connected to oil drain port B3X1 on side B. Valve port X73 on side 7, oil drain cavity A2T on side A, oil drain cavity A3T on side A, and oil drain port B3X2 on side B are all connected to the oil supply end P. The high and low pressure states of oil cavity A1 on side A and oil cavity B1 on side B are controlled by controlling valve F3 on side 3. The high and low pressure states of oil cavity A2 on side A and oil cavity B2 on side B, as well as oil cavity A3 on side A and oil cavity B3 on side B, are controlled by controlling valve F7 on side 7. The combination of these two methods achieves six-stage variable linkage length.

[0088] Table 9 shows the relationship between the valve core position of each controlled valve and the connecting rod length, and the corresponding oil chamber states are shown in Table 7. In this embodiment, under the third and fourth lengths, oil chamber A3 on side A and oil chamber B3 on side B can only be in a low-pressure state (reason: when the number of adjustable plungers involved in the secondary drain circuit is more than one, the drain chambers of each adjustable plunger are connected in series, and at most only one of the controlled oil chambers of each adjustable plunger is in a high-pressure state). Regardless of which connecting rod length needs to be switched to, it is only necessary to control the above two controlled valves according to the valve core position of the controlled valve corresponding to the target connecting rod length to achieve a smooth switching of each plunger to its target position, and after the switching is completed, each plunger can be stably in its target position.

[0089] Table 9 Relationship between valve core position and connecting rod length for each controlled valve

[0090] Obviously, for an eight-stage variable linkage, it is possible to... Figure 10 Based on the existing design, a second controlled valve F2 is added, thus forming a scheme with a single-sided controllable drain port. This scheme has two secondary drain circuits for the first oil chamber on side A. The first secondary drain circuit connects the first oil chamber on side A to the oil supply end P via the relevant valve port of the seventh controlled valve F7, the second drain chamber B2T on side B, the third drain chamber B3T on side B, and the second secondary drain circuit connects the first oil chamber on side A to the oil supply end P via the relevant valve port of the second controlled valve F2, the fourth drain chamber B4T on side B.

[0091] Example 11: To prevent uncontrolled movement or even detachment of the valve core due to engine vibration, a valve core positioning and limiting mechanism is preferably provided on the controlled valve. To facilitate the arrangement of the valve core switching mechanism, the axis of the controlled valve core is preferably arranged parallel or perpendicular to the crankshaft axis, especially a perpendicular arrangement which is beneficial for multi-position multi-way valves. The arrangement position of the controlled valve on the connecting rod body needs to be comprehensively considered based on the actual situation. For example, in Embodiment 1, both controlled valves adopt a parallel arrangement, respectively located in the first valve hole FK1 and the second valve hole FK2 on the connecting rod body 3. Furthermore, regarding... Figure 9 and Figure 10 In the proposed scheme, the third controlled valve is preferably arranged on the side closer to the piston pin, and preferably in a parallel arrangement. The sixth and seventh controlled valves are both preferably arranged on the side closer to the crank pin, and preferably in a vertical arrangement.

[0092] The controlled valve can adopt various structures. This invention takes an axially movable valve core as an example and provides some optional structures for various types of controlled valves mentioned in the previous embodiments. See details. Figures 11-19 .in, Figure 11 and Figure 12These are schematic diagrams of two different structures of the No. 1 controlled valve. Figure 12 (a)- Figure 12 (d) are the front view, top view, AA section and BB section of the second structure of the valve, respectively. Figure 13 and Figure 14 These are schematic diagrams of two different structures of the No. 2 controlled valve. Figure 13 (a) and Figure 13 (b) are the front view and top view sectional views corresponding to the first structure, respectively. Figure 14 (a)- Figure 14 (d) are the front view, top view, AA section and BB section corresponding to the second structure, respectively. Figure 15 This is a schematic diagram of one possible structure of the No. 3 controlled valve. Figure 15 (a)- Figure 15 (d) are the front view, top view, AA section and BB section of the valve, respectively. Figure 16 This is a schematic diagram of one possible structure of the No. 5 controlled valve, in which... Figure 16 (a) and Figure 16 (b) are the front view and top view sectional views of the valve, respectively. Figure 17 and Figure 18 These are schematic diagrams of two different structures of the controlled valve No. 6. Figure 17 (a) and Figure 17 (b) are the front view and top view sectional views of the valve, respectively. Figure 18 (a)- Figure 18 (e) are the front view, top view, section AA, section BB, and section CC of the valve, respectively. Figure 19 This is a schematic diagram of one possible structure of the No. 7 controlled valve. Figure 19 (a)- Figure 19 (h) shows the front view, top view, AA section, BB section, CC section, DD section, EE section, and FF section of the valve, respectively. The main differences between the controlled valves are: the number of valve ports and the number of stable working positions of the valve core; the different connectivity relationships between the valve ports under each stable working position of the valve core; and the different positions of the valve ports, limit blocks, and spring ball positioning mechanisms, as well as the different arrangements of the corresponding valve core oil passages (such as oil grooves or oil holes). The installation, switching, positioning, limiting, and flow rate control methods for each controlled valve are all conventional techniques and will not be repeated.

[0093] Example 12: The plunger involved in this invention can also be a combined plunger, which has a variable plunger length. When using a combined plunger, the number of variable connecting rod length stages can be significantly increased while maintaining the same total number of plungers. Figure 20 This is a schematic diagram of a combined plunger with a hollow plunger, wherein, Figure 20(a) and (b) show the combined plunger and its relative connecting rod state when both oil chamber C0 (zero chamber) and oil chamber C1 (one chamber) are in a low-pressure state and when both are in a high-pressure state, respectively. Figure 20 As can be seen, this combined plunger mainly includes a central plunger ZC0 and a first hollow plunger ZC1. The central plunger ZC0 is coaxially nested inside the first hollow plunger ZC1, and the upper end of the central plunger ZC0 extends from the through hole above the first hollow plunger ZC1. A first plug DKC1 is fixedly installed at the lower end of the first hollow plunger ZC1, thus forming a combined plunger with one hollow plunger and achieving the upper limit of the stroke of the central plunger ZC0 relative to the first hollow plunger ZC1. A zero oil chamber C0 is formed below the central plunger ZC0 and between it and the first plug DKC1, which forms the control oil chamber for controlling the length of this combined plunger.

[0094] For multi-stage variable linkages, this combined plunger can be used to replace the aforementioned conventional plunger. In this embodiment, it is installed inside the linkage body 3, with the plug DKC fixedly installed on the corresponding mounting hole of the linkage body 3, and the upper end of the central plunger ZC0 protruding from the through hole on the plug DKC, thereby obtaining the upper limit of the stroke of the first hollow plunger ZC1 relative to the linkage body 3. A first oil chamber C1 is formed below the first hollow plunger ZC1 (i.e., below the first plug DKC1), which is the controlled oil chamber of this combined plunger, used to control the position of the first hollow plunger ZC1 relative to the linkage body 3. Table 10 shows the relationship between the state of each oil chamber and the plunger length, as well as the positions of the first hollow plunger and the central plunger relative to the linkage body.

[0095] Table 10 Relationship between the state of each oil chamber and the plunger length and position of the central plunger

[0096] Application example: For instance, replacing the second plunger ZA2 on side A in Example 1 with a combined plunger having one hollow plunger results in a six-stage variable connecting rod. If the second plunger ZB2 on side B is also replaced with this combined plunger, an eight-stage variable connecting rod is obtained. If a conventional plunger (denoted as A2, representing its controlled oil chamber) is added after the combined plunger on side A, a ten-stage variable connecting rod is obtained. Table 11 shows the relationship between the corresponding oil chamber states and connecting rod lengths (adding an A before the combined plunger symbol indicates it is located on side A, and adding a B indicates it is located on side B). And so on.

[0097] Preferably, the upper end of the central plunger ZC0 forms a mating fit with the through hole on the plug DKC and the through hole on the first hollow plunger ZC1. A first drain chamber C1T is formed between the lower part of the plug DKC and the first hollow plunger ZC1, and a zero drain chamber C0T is formed between the upper end of the central plunger ZC0 and the first hollow plunger ZC1. Correspondingly, this includes oil passages connecting the aforementioned drain chambers to the oil supply or drain end. When a controllable drain port is required, a first drain port C1X1 and a second drain port C1X2 are provided on the connecting rod body 3, and a zero first drain port C0X1 and a zero second drain port C0X2 are provided on the first hollow plunger ZC1. Whether these ports are blocked is determined by the positions of the first hollow plunger ZC1 and the central plunger ZC0, respectively. The oil passage layout and control method for the variable connecting rod with combined plungers are similar to those described above and will not be repeated.

[0098] Table 11 Relationship between the state of each oil chamber and the length of the connecting rod

[0099] Example 13: Figure 21 This is a schematic diagram of a combined plunger with two hollow plungers. Figure 21 (a) and Figure 21 (b) Schematic diagrams of the plunger structure when all three oil chambers are under low pressure and when all three are under high pressure, respectively. Figure 21 As can be seen, a second hollow plunger ZC2, nested and coaxially arranged with the first hollow plunger ZC1, is further added outside it, and a second plug DKC2 is fixedly installed at the lower end of the second hollow plunger ZC2. This forms a combined plunger with two hollow plungers, and the upper limit of the stroke of the first hollow plunger ZC1 relative to the second hollow plunger ZC2 is obtained. Correspondingly, a controlled oil chamber (second oil chamber C2) for controlling this combined plunger and control oil chambers (zero oil chamber C0 and first oil chamber C1) for controlling the length of this combined plunger are formed. Table 12 shows the relationship between the state of each oil chamber and the plunger length and the position of the central plunger.

[0100] Table 12 Relationship between the state of each oil cavity and the effective length of the plunger and the position of the central plunger

[0101] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A multi-stage variable linkage, characterized in that, The device includes a connecting rod body and an eccentric rocker arm mounted on the connecting rod body. The outer circle of the eccentric rocker arm is rotatably connected to a through hole on the connecting rod body. The inner hole of the eccentric rocker arm is connected to a piston pin or a crank pin. The outer circle axis of the eccentric rocker arm is parallel to but not collinear with the inner hole axis of the eccentric rocker arm. A-side connecting member and B-side connecting member are respectively connected to both sides of the eccentric rocker arm. The other end of the A-side connecting member is connected to the first plunger on the A side, and the other end of the B-side connecting member is connected to the first plunger on the B side. At least one adjustable plunger is connected in series on the side of the first plunger on the A side and / or the first plunger on the B side away from the eccentric rocker arm. In this configuration, there are M pistons on side A, arranged in series with their effective stroke decreasing sequentially away from the eccentric rocker arm. The side of each piston on side A away from the eccentric rocker arm forms a controlled oil chamber A1...AM. There are N pistons on side B, arranged in series with their effective stroke decreasing sequentially away from the eccentric rocker arm. The side of each piston on side B away from the eccentric rocker arm forms a controlled oil chamber B1...BN. One of M and N is at least 2, and the other is at least 1. By controlling the hydraulic state of each controlled oil chamber, different effective connecting rod lengths can be obtained.

2. The multi-stage variable linkage according to claim 1, characterized in that, The eccentric swing arm can be a circumferentially split eccentric swing arm, a radially split eccentric swing arm, or a one-piece eccentric swing arm, wherein: When a circumferentially split eccentric swing arm is used, the eccentric swing arm includes an eccentric sleeve and a swing arm; the corresponding part of the connecting rod body adopts a hollow structure along the axial direction, and the swing arm is inserted into the hollow structure of the connecting rod body, or the swing arm itself is a swing arm with a hollow structure along the axial direction, and the connecting rod body is inserted into the hollow structure of the swing arm; after the swing arm and the connecting rod body are inserted, the inner hole of the swing arm is aligned with the through hole of the connecting rod body, and the eccentric sleeve is fitted into the inner hole of the swing arm and the through hole of the connecting rod body, so that the eccentric sleeve swings synchronously with the swing arm and the outer circle of the eccentric sleeve is located in the through hole of the connecting rod body, so as to limit the relative rotation of the eccentric swing arm and the connecting rod body; When a radially split eccentric swing arm is used, the eccentric swing arm includes an eccentric swing arm body one and an eccentric swing arm body two, which are fixedly connected to form the outer circle, inner hole, and swing arm portion of the eccentric swing arm; the connecting rod body also adopts a radially split structure, and the connecting rod body includes a connecting rod body and an end cap, which are fixedly connected to form the through hole portion of the connecting rod body; the corresponding parts of the connecting rod body and the end cap both adopt a hollow structure along the axial direction. After the eccentric swing arm body one and the eccentric swing arm body two are fixedly connected, the eccentric... The swing arm portion of the swing arm is inserted into the hollow structure of the connecting rod body, such that the outer circle of the eccentric swing arm is located within the through hole, and the relative rotation of the eccentric swing arm and the connecting rod body is limited by the end cap; or, the swing arm portion of the eccentric swing arm adopts a hollow structure along the axial direction, after the first eccentric swing arm body and the second eccentric swing arm body are fixedly connected, the connecting rod body is inserted into the hollow structure of the swing arm portion, such that the outer circle of the eccentric swing arm is located within the through hole, and the relative rotation of the eccentric swing arm and the connecting rod body is limited by the end cap; When an integrated eccentric swing arm is used, the connecting rod body adopts a radially split structure. The connecting rod body includes a connecting rod body and an end cap, which are fixedly connected to form a through hole portion of the connecting rod body. The corresponding portions of the connecting rod body and the end cap both adopt a hollow structure along the axial direction. The swing arm portion of the eccentric swing arm is inserted into the hollow structure of the connecting rod body, and the outer circle of the eccentric swing arm is located within the through hole. The end cap limits the relative rotation between the eccentric swing arm and the connecting rod body. Alternatively, the swing arm portion of the eccentric swing arm adopts a hollow structure along the axial direction. The connecting rod body is inserted into the hollow structure of the swing arm portion, and the outer circle of the eccentric swing arm is located within the through hole. The end cap limits the relative rotation between the eccentric swing arm and the connecting rod body.

3. A multi-stage variable linkage according to claim 1, characterized in that, It also includes a hydraulic control system, which includes a check valve and a controlled valve; the hydraulic control system includes a primary oil supply circuit that supplies oil to the controlled oil chamber A1 and the controlled oil chamber B1 in a one-way manner with only oil inflow and no outflow from the oil supply end; a secondary oil supply circuit that supplies oil to each adjustable plunger in a one-way manner from the oil supply end and / or the controlled oil chamber A1 and / or the controlled oil chamber B1; and a primary oil drain circuit that connects each controlled oil chamber to the oil supply end or to the oil drain end. The one-way valve is installed on the oil supply line to achieve one-way oil supply, and the controlled valve is used to control the on / off state of each oil circuit; the hydraulic control system controls the working state of the controlled valve to control the high and low pressure states of each controlled oil chamber: the high pressure state refers to the controlled oil chamber being in a one-way oil supply state where hydraulic oil only enters and does not exit, and the corresponding controlled oil chamber's inlet oil circuit is connected and its drain oil circuit is disconnected; the low pressure state refers to the controlled oil chamber being connected to the oil supply end or the drain end, and the corresponding controlled oil chamber's inlet oil circuit and drain oil circuit are both connected, or the corresponding controlled oil chamber's inlet oil circuit is disconnected and its drain oil circuit is connected; The hydraulic control system is used to ensure that one of the controlled oil chambers A1 and B1 is in a high-pressure state and the other is in a low-pressure state. Different effective link lengths are obtained by controlling the position of the low-pressure oil chamber and the position of the first high-pressure oil chamber among the remaining controlled oil chambers on that side: When controlled oil chamber A1 is in a high-pressure state, B1 is in a low-pressure state; the effective link length is determined by controlling the position of the first high-pressure controlled oil chamber among B2…BN, while the remaining controlled oil chambers are allowed to be in either a high-pressure or low-pressure state; When controlled oil chamber B1 is in a high-pressure state, A1 is in a low-pressure state; the effective link length is determined by controlling the position of the first high-pressure controlled oil chamber among A2…AM, while the remaining controlled oil chambers are allowed to be in either a high-pressure or low-pressure state; The hydraulic control system controls the controlled valves according to the engine operating conditions, ensuring that the high and low pressure states of each controlled oil chamber are at the target high and low pressure states corresponding to the target effective link length.

4. A multi-stage variable linkage according to claim 3, characterized in that, The upper end of the adjustable plunger forms a mating structure with its mounting hole to obtain the oil drain chamber of the adjustable plunger; the hydraulic control system also includes an oil circuit connecting the oil drain chamber to the oil supply end or to the oil drain end.

5. A multi-stage variable linkage according to claim 4, characterized in that, At least one of the adjustable plungers has a controllable drain port on the side wall of its drain chamber: when the adjustable plunger is at its upper limit position, the controllable drain port is blocked by the adjustable plunger and is not connected to the drain chamber of the adjustable plunger; when the adjustable plunger is not at its upper limit position, the controllable drain port is not blocked by the adjustable plunger and is connected to the drain chamber of the adjustable plunger. The hydraulic control system further includes at least one secondary drain circuit for the controlled oil chambers A1 and / or B1; the secondary drain circuit is an oil circuit that connects the controlled oil chambers to the oil supply end or the oil drain end through a set of valve ports of the controlled valve and at least one drain chamber of an adjustable plunger with a controllable drain port: when the number of adjustable plungers involved in the oil circuit is more than one, the drain chambers of the corresponding adjustable plungers are connected in series and at most only one of the controlled oil chambers of each adjustable plunger is in a high-pressure state; the on / off state of the secondary drain circuit is determined by the working state of the controlled valve and the position of the corresponding adjustable plungers. When it is necessary for all the controlled oil chambers of the adjustable plungers in the oil circuit to switch to the low-pressure state, the hydraulic control system also controls the corresponding valve port of the controlled valve to open, so that the oil circuit is in the disconnected state. When the controlled oil chamber of any one of the adjustable plungers in the oil circuit needs to switch from a low-pressure state to a high-pressure state, the hydraulic control system controls the corresponding valve port of the controlled valve to connect, so that the on / off state of the oil circuit is jointly determined by the positions of the corresponding adjustable plungers: during the switching process, when the adjustable plunger has not moved to its upper limit position, the oil circuit is in a connected state; when the adjustable plunger moves to its upper limit position, the oil circuit is in a disconnected state.

6. A multi-stage variable linkage according to claim 5, characterized in that, The secondary oil drain circuit of the controlled oil chamber A1 or B1 includes an oil drain chamber with an adjustable plunger and a controllable oil drain port on the opposite side of the controlled oil chamber.

7. A multi-stage variable linkage according to claim 5, characterized in that, A controllable oil drain port is provided on the oil drain chamber sidewall of the adjustable plunger on the side with the smaller plunger diameter between plunger No. 1 on side A and plunger No. 1 on side B.

8. A multi-stage variable linkage according to claim 3, characterized in that, The hydraulic control system also includes a three-stage drain circuit for the controlled oil chambers A1 and / or B1; the three-stage drain circuit is an oil circuit connecting the controlled oil chambers to the oil supply end or the drain end via controlled valves; the hydraulic control system also has a three-stage drain mode; when it is necessary to switch the controlled oil chamber of at least one adjustable plunger from a low-pressure state to a high-pressure state, the system determines whether to activate the three-stage drain mode based on the effective length of the connecting rod before switching and the effective length of the target connecting rod. When the three-stage oil drain mode needs to be activated, during the switching process, the hydraulic control system controls the corresponding controlled valve to switch the oil circuit to the connected state. After all the adjustable plungers reach their upper limit, the three-stage oil drain mode is closed, and the hydraulic control system controls the corresponding controlled valve to switch the oil circuit to the disconnected state. When the three-stage oil drain mode is not required, the hydraulic control system controls the corresponding controlled valve to keep the oil circuit in the disconnected state.

9. A multi-stage variable linkage according to claim 3, characterized in that, The hydraulic control system also includes a reciprocating oil drain mode; when at least one adjustable plunger's controlled oil chamber needs to switch from a low-pressure state to a high-pressure state, the system determines whether to activate the reciprocating oil drain mode based on the effective length of the connecting rod before switching and the effective length of the target connecting rod. When the reciprocating oil drain mode needs to be activated, during the switching process, the reciprocating oil drain mode is activated, and the hydraulic control system also controls the corresponding controlled valve to repeatedly switch the high and low pressure states of the controlled oil chambers A1 and B1; after all the adjustable plungers reach their upper limit, the reciprocating oil drain mode is deactivated, and the hydraulic control system controls the corresponding controlled valve to switch the high and low pressure states of the controlled oil chambers A1 and B1 to the target high and low pressure states. When the reciprocating oil drain mode is not required, the hydraulic control system controls the corresponding controlled valves to switch the high and low pressure states of the controlled oil chambers A1 and B1 to the target high and low pressure states.

10. A multi-stage variable linkage according to claim 3, characterized in that, The axis of the valve core of the controlled valve is parallel or perpendicular to the crankshaft axis, and a valve core positioning and limiting mechanism is provided on the controlled valve.

11. A multi-stage variable linkage according to claim 1, characterized in that, The plunger is a composite plunger; the composite plunger includes one central plunger and at least one hollow plunger; the number of hollow plungers is L, namely hollow plunger No. 1, hollow plunger No. 2...L hollow plunger, where L is at least 1; the central plunger and each hollow plunger are arranged coaxially in a nested manner, and in any two adjacent plungers, the plunger located on the radially outer side forms an axial limit on the plunger located on the radially inner side to define the upper limit of the stroke of the inner plunger relative to the outer plunger; the central plunger and each hollow plunger form a controlled oil chamber C0, C1, C2...CL on the side away from the eccentric rocker arm; the controlled oil chambers C0, C1, C2...CL-1 are the control oil chambers for the effective length of the composite plunger, and different effective plunger lengths are obtained by controlling the hydraulic state of the controlled oil chambers C0, C1, C2...CL-1; the controlled oil chamber CL is the controlled oil chamber of the composite plunger.

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