A hydraulic variable valve mechanism and method for an engine

Abstract

This invention discloses a hydraulic variable valve mechanism and method for engines, relating to the field of engine technology. It solves the problem of excessively advanced valve closing angle at low speeds in existing valve mechanisms, and has the beneficial effect of being applicable to late Miller cycles. The specific solution is as follows: A hydraulic variable valve mechanism for engines includes a drain hole on the side of a tappet, one end of which penetrates the top of the tappet and is connected to a high-pressure oil circuit. A housing has a drain groove on the side of the tappet, and the drain hole can communicate with the drain groove. A circumferential oil passage groove is provided for the spool valve. An opening is provided in the housing. When the spool valve is working and during the tappet movement, the drain hole, the drain groove, the oil passage groove, and the opening can all be connected. The transfer piston includes a throttling buffer component. The throttling buffer component has a circumferential recess to accommodate hydraulic oil. The throttling buffer component can perform reciprocating linear motion to adjust the communication area between the circumferential recess and the opening.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a hydraulic variable valve mechanism and method for engines. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With increasingly stringent emission and fuel consumption regulations for automobiles, engine manufacturers are increasingly looking to combine the traditional Otto cycle (Diesel cycle for diesel engines) and Miller cycle to achieve energy conservation and emission reduction. Miller cycle technology is a cycle method that improves the thermal efficiency of internal combustion engines by changing the intake valve closing angle to achieve an expansion ratio greater than the compression ratio. In existing technology, an intake valve closing angle earlier than the traditional intake valve closing angle is called an early Miller cycle, and a later intake valve closing angle is called a late Miller cycle.

[0004] For engines using the early Miller cycle, a smaller valve opening is typically used under low-speed, low-load conditions to achieve the early Miller cycle and meet the demands of low load and low speed, thus achieving energy conservation and emission reduction. Under high-speed, high-load conditions, the traditional valve opening remains unchanged. For engines using the late Miller cycle, a larger valve opening is desired for full-load conditions, achieving the late Miller cycle and thus energy conservation and emission reduction. A smaller valve opening is maintained, using the traditional valve opening for acceleration and high-speed cruising.

[0005] Patent CN116557100B discloses a hydraulic variable valve mechanism and its working method for an engine. This design places a small drain hole on one side of the tappet, allowing high-pressure oil to be discharged to the accumulator through this hole. A problem with this structure is that due to the large volume of the accumulator, the hydraulic oil pressure changes abruptly when high-pressure oil is discharged from the high-pressure circuit to the low-pressure circuit. This causes a significant change in the small-opening valve closing angle with engine speed, resulting in a much earlier valve closing angle at low speeds and a less earlier valve closing angle at high speeds. The corresponding engine performance curve is shown below. Figure 4 As shown. This valve mechanism is more suitable for engines using the early Miller cycle. If used in a late Miller cycle, the small valve opening at low speeds results in insufficient intake air volume, which is detrimental to acceleration. If the accumulator volume is reduced, when high-pressure oil is discharged from the high-pressure oil circuit to the low-pressure oil circuit, the hydraulic oil falls directly into the smaller accumulator without buffering, causing fluctuations in the high-pressure hydraulic oil, which in turn leads to fluctuations in the valve closing angle. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a hydraulic variable valve mechanism for engines, which can prevent the hydraulic oil pressure from dropping suddenly when high-pressure oil is discharged from the high-pressure oil circuit to the low-pressure oil circuit, and also provides a certain buffering effect for the entry of hydraulic oil.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] A hydraulic variable valve mechanism for an engine includes a housing, a tappet and a valve piston, a lubrication oil passage, and a high-pressure oil passage formed between the tappet and the valve piston. The lubrication oil passage is connected to the high-pressure oil passage, and the valve piston can move along the piston chamber. The housing also includes a spool valve and a transfer piston. An oil drain hole is provided on the side of the tappet, one end of which passes through the top of the tappet and connects to the high-pressure oil passage. An oil drain groove is provided on the side of the tappet, and the oil drain hole can communicate with the oil drain groove. The spool valve has a circumferential oil passage. The housing has an opening. When the spool valve is working and during the tappet's movement, the oil drain hole, the housing oil drain groove, the spool valve oil passage, and the opening can all be connected. The transfer piston includes a throttling buffer component with a circumferential recess to accommodate hydraulic oil. The circumferential recess can communicate with the opening, and the throttling buffer component can perform reciprocating linear motion to adjust the communication area between the circumferential recess and the opening.

[0009] As described above, in a hydraulic variable valve mechanism for an engine, a portion of the throttling buffer component is hollow, and the circumferential recess is provided in the middle section of the throttling buffer component;

[0010] A spring seat is provided at the bottom of the throttling buffer component. The spring seat is installed on the housing and extends beyond the housing. An elastic element is provided between the spring seat and the throttling buffer component. A limiting step is formed at one end of the spring seat to limit one end of the throttling buffer component.

[0011] As described above, a hydraulic variable valve mechanism for an engine has a first cavity on one side of the throttling buffer component, which is connected to the high-pressure oil circuit and the circumferential recess. A second cavity is provided on the other side of the throttling buffer component, which is located below the first cavity. An elastic element is provided between the second cavity and the spring seat to reset the throttling buffer component.

[0012] As described above, a hydraulic variable valve mechanism for an engine is provided in the housing, the end of the first oil passage is the opening, the slide valve oil passage is connected to the opening and the circumferential recess through the first oil passage, and when the slide valve is not working, the first oil passage is connected to the lower side of the circumferential recess through the opening;

[0013] The housing is also provided with a second oil passage, one end of which is connected to the oil drain groove of the housing, and the other end of which can be connected to the oil passage of the slide valve.

[0014] As described above, in a hydraulic variable valve mechanism for an engine, the throttling buffer component has a blocking part on one side of the circumferential recess, and the height of the blocking part is greater than the height of the first oil passage.

[0015] When the throttling buffer component operates to its lower limit position, the sealing part completely seals the opening.

[0016] In the hydraulic variable valve mechanism for an engine described above, the height of the circumferential recess is less than the height of the first oil passage.

[0017] As described above, in a hydraulic variable valve mechanism for an engine, the first cavity is connected to a pipeline, the pipeline is connected to the high-pressure oil circuit through a second check valve, and a first check valve is provided between the lubricating oil circuit and the second check valve.

[0018] In the hydraulic variable valve mechanism for an engine described above, the diameter of the drain hole is smaller than the height of the drain groove in the housing;

[0019] When the drain hole is connected to the drain groove of the casing, the tappet moves to the vicinity of the tappet's upper stop point.

[0020] As described above, in a hydraulic variable valve mechanism for an engine, the housing is provided with a control oil circuit, which is connected to the slide valve via a solenoid valve, and the solenoid valve is a normally closed solenoid valve.

[0021] Secondly, the present invention also provides a method for operating a hydraulic variable valve mechanism for an engine, comprising the following:

[0022] When the spool valve is not in operation, it cuts off the connection between the oil drain groove in the housing and the opening, and the valve always operates at a large opening.

[0023] When the spool valve is activated, it moves to another extreme position under the action of oil pressure. The oil drain groove of the housing is connected to the opening. When the oil drain hole moves to the position of the oil drain groove of the housing, the oil drain hole, the oil drain groove of the housing, the oil passage groove of the spool valve, and the opening are all connected. The hydraulic oil is drained through the spool valve to the circumferential recess of the transfer piston, so that the valve works in a small opening state. The throttling buffer component can perform reciprocating linear motion to adjust the communication area between the circumferential recess and the opening, so as to ensure that the valve is in a stable working state.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1) The variable valve mechanism provided by the present invention has an oil drain hole on the side of the tappet. During the operation of the tappet, the oil drain hole can communicate with the oil drain groove of the housing, so that the hydraulic oil in the high-pressure oil circuit can enter the oil drain groove of the housing. When the slide valve is working, the hydraulic oil can enter the opening of the transfer piston through the oil drain groove of the housing and the oil passage groove of the slide valve, and enter the circumferential recess. The throttling buffer component can perform reciprocating linear motion to adjust the communication area between the circumferential recess and the opening, so as to buffer by gradually reducing the communication area between the two, avoiding large fluctuations in the pressure of the hydraulic oil in the high-pressure oil circuit, so that the valve closing angle at a small opening will not change significantly with the speed, making it suitable for vehicles with late Miller cycle.

[0026] 2) In this invention, the transfer piston structure is reasonably set, and the circumferential recess is connected to the first cavity. Thus, when the slide valve is working, after the oil drain hole of the tappet is connected to the oil drain groove of the housing, the hydraulic oil enters the recess and then enters the first cavity. In the initial state, the opening is connected to the lower side of the circumferential recess. As the amount of hydraulic oil increases, it overcomes the resistance of the elastic element and causes the throttling buffer component to move downward along the housing, thereby gradually adjusting the connection area between the opening and the circumferential recess, thus ensuring that the valve change is stable when the valve is at a small opening and there will be no sudden change.

[0027] 3) The hydraulic variable valve mechanism provided by the present invention has an oil drain starting point when the drain hole moves upward to the position of the drain groove in the housing. The phase angle from this point to the point where the tappet moves downward and the drain hole leaves the drain groove in the housing is the oil drain phase angle. Because of the setting of the throttling buffer component (the throttling buffer component blocks the opening of the housing), the actual oil drain phase angle is smaller than the oil drain phase angle within the usable speed range. After the actual oil drain ending point, the valve follows the tappet and runs according to the cam profile.

[0028] 4) The hydraulic variable valve mechanism provided by the present invention replaces the accumulator with a transfer piston. In addition to the function of storing hydraulic oil as an accumulator, the transfer piston is also equipped with a throttling buffer component, which can control the discharge of hydraulic oil to ensure that the valve closing angle remains consistent at different speeds. In this way, the transfer piston can not only absorb a part of the kinetic energy, but also has a buffering effect. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a control principle diagram of a hydraulic variable valve mechanism for an engine according to one or more embodiments of the present invention.

[0031] Figure 2This is a schematic diagram of the structure of a hydraulic variable valve mechanism for an engine according to one or more embodiments of the present invention.

[0032] Figure 3 This is a performance curve diagram of a hydraulic variable valve mechanism for an engine according to one or more embodiments of the present invention.

[0033] Figure 4 It is a performance curve of the variable valve mechanism in patent CN116557100B in the prior art.

[0034] Figure 5 This is a performance curve of a hydraulic variable valve mechanism for an engine at different speeds according to one or more embodiments of the present invention.

[0035] Figure 6 This is a schematic diagram of the initial state of the transfer piston in a hydraulic variable valve mechanism for an engine according to one or more embodiments of the present invention.

[0036] Figure 7 This is a schematic diagram of the sealing housing opening of the transfer piston sealing part in a hydraulic variable valve mechanism for an engine according to one or more embodiments of the present invention.

[0037] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0038] The components are: 1. Valve; 2. Valve piston; 3. Housing; 4. Tappet; 5. Housing drain groove; 6. Drain hole; 7. Cam; 8. Spool valve; 9. Spool valve oil passage groove; 10. Circular recess; 11. Transfer piston; 12. Throttling buffer component; 13. Spring seat; 14. First chamber; 15. Second chamber; 16. First oil passage; 17. Second oil passage; 18. High-pressure oil passage; 19. Lubricating oil passage; 20. Control oil passage; 21. Oil pump; 22. Solenoid valve; 23. First check valve; 24. Second check valve; 25. Connecting hole; 26. Limiting step; 27. Elastic element. Detailed Implementation

[0039] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] As described in the background section, the prior art has the problem that the valve closing angle is advanced too much at low speeds. In order to solve the above technical problem, the present invention proposes a hydraulic variable valve mechanism for engines.

[0042] Example 1

[0043] In a typical embodiment of the present invention, reference is made to Figure 1 and Figure 2 As shown, a hydraulic variable valve mechanism for an engine includes a housing 3, a tappet 4 and a valve piston 2, a lubrication oil passage 19, and a high-pressure oil passage 18 formed between the tappet 4 and the valve piston 2. The lubrication oil passage 19 is connected to the high-pressure oil passage 18. The valve piston 2 can move along the piston chamber. The housing 3 is equipped with a slide valve 8 and a transfer piston 11. An oil drain hole 6 is opened on the side of the tappet 4, one end of which passes through the top of the tappet 4 and is connected to the high-pressure oil passage 18 (i.e., the oil drain hole 6 is connected to the tappet chamber). The housing 3 has an oil drain hole 6 on the side of the tappet 4. The housing has an oil drain groove 5, and the oil drain hole 6 can communicate with the housing oil drain groove 5. The slide valve 8 is provided with a slide valve oil passage groove 9 in a circumferential direction. The housing 3 is provided with an opening. When the slide valve 8 is working and during the movement of the tappet 4, the oil drain hole 6, the housing oil drain groove 5, the slide valve oil passage groove 9, and the opening can all be connected. The transfer piston 11 is provided with a throttling buffer component 12 inside. The throttling buffer component 12 is provided with a circumferential recess 10 to accommodate hydraulic oil. The circumferential recess can communicate with the opening. The throttling buffer component 12 can perform reciprocating linear motion to adjust the communication area between the circumferential recess 10 and the opening.

[0044] One end of the oil drain hole 6 is located in the middle section of the push rod 4. When the oil drain hole 6 is connected to the oil drain groove 5 of the housing, the push rod moves to the vicinity of the top dead center of the push rod. In this way, the oil drain hole 6 and the oil drain groove 5 of the housing can remain connected during the movement of the push rod near the top dead center. The height of the oil drain hole 6 is less than the height of the oil drain groove 5 of the housing. During the movement of the push rod 4, the oil drain hole 6 and the oil drain groove 5 of the housing are connected for a relatively long time. The diameter of the oil drain hole 6 is less than the height of the oil drain groove 5 of the housing.

[0045] It should be noted that the slide valve 8 is provided with a slide valve oil passage groove 9 in the circumferential direction. One side of the slide valve oil passage groove 9 can be connected to the housing oil drain groove 5, and the other side can be connected to the circumferential recess 10 at the transfer piston.

[0046] The hydraulic variable valve mechanism provided in this embodiment has an oil drain hole 6 on the side of the tappet 4. During the operation of the tappet 4, the oil drain hole 6 can communicate with the oil drain groove 5 of the housing, so that the hydraulic oil in the high-pressure oil circuit can enter the oil drain groove 5 of the housing. When the slide valve 8 is working, the hydraulic oil can enter the opening of the transfer piston through the oil drain groove 5 of the housing and the oil passage groove 9 of the slide valve, and enter the circumferential recess 10. The throttling buffer component 12 can perform reciprocating linear motion to adjust the communication area between the circumferential recess 10 and the opening, so as to buffer by gradually reducing the communication area between the two, avoiding large fluctuations in the pressure of the hydraulic oil in the high-pressure oil circuit 18, so that the valve closing angle at a small opening will not change significantly with the speed, which is suitable for vehicles with late Miller cycle.

[0047] refer to Figure 6 and Figure 7 As shown, the transfer piston 11 is installed at the housing 3, the throttling buffer component 12 can slide linearly relative to the housing 3, the opening can communicate with the oil drain groove 5 of the housing, the opening can be a circular hole, a section of the throttling buffer component 12 is hollow, and a circumferential recess 10 is provided in the middle section of the throttling buffer component 12.

[0048] Specifically, Figure 6 In the initial state of the transfer piston, the circumferential recess 10 of the transfer piston is connected to the first oil passage 16. A first cavity 14 is provided on one side of the throttling buffer component. The first cavity 14 is connected to the circumferential recess 10 through the connecting hole 25. The hydraulic oil (high pressure) entering the circumferential recess 10 enters the first cavity 14 through the connection between the circumferential recess 10 and the first cavity 14. The first cavity 14 is on top, which can provide downward force to the throttling buffer component. After the pressure of the hydraulic oil in the first cavity 14 reaches the set value, it pushes the throttling buffer component to move downward along the housing 3, thereby gradually adjusting the communication area between the opening and the circumferential recess. A second cavity 15 is provided on the other side of the throttling buffer component 12. The second cavity 15 is below the first cavity 14. The setting of the second cavity 15 facilitates the setting of the elastic element 27. A positioning step is provided on the top of the second cavity 15 to position one end of the elastic element 27. The setting of the second cavity 15 also helps to control the mass of the throttling buffer component.

[0049] A spring seat 13 is provided at the bottom of the throttling buffer component. The spring seat 13 is installed on the housing 3 and extends beyond the housing 3. An elastic element, which is a spring, is provided between the spring seat 13 and the throttling buffer component 12. A limiting step 26 is formed at the upper end of the spring seat to limit one end of the throttling buffer component. When the throttling buffer component 12 contacts the limiting step 26, the circumferential recess 10 is not connected to the opening, that is, the sealing part blocks the opening at this time. An elastic element 27, which is a spring, is provided between the second cavity 15 and the spring seat 13 to reset the throttling buffer component 12.

[0050] It should be noted that when the top of the throttling buffer component 12 contacts the limiting step 26, the opening is connected to the bottom of the circumferential recess. As hydraulic oil continues to flow in, the throttling buffer component 12 moves downward, and the flow area of ​​the opening and the circumferential recess 10 gradually increases. As the throttling buffer component 12 continues to move downward, the flow area of ​​the opening and the circumferential recess 10 gradually decreases.

[0051] In this embodiment, the housing 3 is provided with a first oil passage 16, the end of which is an opening. The slide valve oil passage 9 can be connected to the opening and the circumferential recess 10 through the first oil passage. When the slide valve 8 is not working, the first oil passage 16 is connected to the lower side of the circumferential recess 10 through the opening. The housing 3 is also provided with a second oil passage 17. The diameter of the second oil passage 17 is smaller than the height of the housing drain groove 5. One end of the second oil passage 17 is connected to the housing drain groove 5, and the other end can be connected to the slide valve oil passage 9. This allows the slide valve 8 to be positioned between the tappet 4 and the transfer piston 11.

[0052] It is easy to understand that the throttling buffer component 12 has a sealing part on one side of the circumferential recess 10. The height of the sealing part is greater than the height of the first oil passage 16. The sealing part is the side wall of the first cavity 14. The side wall of the first cavity 14 is in contact with the inner wall of the housing 3. The side wall of the second cavity 15 is also in contact with the inner wall of the housing 3.

[0053] In this embodiment, the height of the circumferential recess 10 is less than the height of the first oil passage 16, and the area of ​​the opening is greater than or equal to the area of ​​the longitudinal section of the first oil passage 16.

[0054] Among them, the shell oil drain groove 5 is a shell oil drain annular groove, and the slide valve oil passage groove 9 is also a slide valve oil passage annular groove.

[0055] Additionally, housing 3 is equipped with a control oil circuit 20, which is connected to spool valve 8 via solenoid valve 22 and oil pump 21. Solenoid valve 22 is a normally closed solenoid valve. When solenoid valve 22 is not energized, spool valve 8 disconnects the connection between housing drain groove 5 and opening, and valve 1 always operates at a large opening. When solenoid valve 22 is energized, it connects control oil circuit 20 to spool valve 8. Under oil pressure, spool valve 8 moves to another extreme position, connecting spool valve to oil groove 9, opening, and circumferential recess 10. When tappet drain hole 6 moves to the position of housing drain groove 5, high-pressure hydraulic oil is drained through spool valve 8 into the circumferential recess 10 of the transfer piston, thus valve 1 operates at a small opening. When the tappet descends and closes tappet drain hole 6, the connection between drain hole and housing drain groove is closed, and piston continues to fall with tappet until valve closes.

[0056] refer to Figure 2As shown, the first chamber 14 of the transfer piston is connected to a pipe, which is located inside the housing 3 and is connected to the high-pressure oil circuit 18 through the second check valve 24. In this way, the hydraulic oil stored in the first chamber 14 can flow back to the high-pressure oil circuit 18 through the second check valve 24, so that the hydraulic oil flows to the high-pressure oil circuit 18 through the second check valve 24 to ensure the smooth operation of the next cycle. A first check valve 23 is provided between the lubrication oil circuit and the second check valve 24, so that the hydraulic oil flows to the second check valve 24 through the first check valve 23. That is, the lubrication oil circuit supplies oil to the high-pressure oil circuit 18 through the second check valve 24 and the first check valve 23.

[0057] The hydraulic variable valve mechanism provided in this embodiment has the following performance curve: Figure 3 As shown. The dashed line represents the large opening state, in which there is no oil leakage throughout. The solid line represents the small opening state. When the oil drain hole 6 moves upward to the position of the oil drain groove 5 in the housing, it is the oil leakage start point. From this point to the point where the tappet 4 moves downward and the oil drain hole 6 leaves the oil drain groove in the housing, the phase angle is the oil leakage phase angle. Because of the setting of the throttling buffer component (the throttling buffer component blocks the opening of the housing), the actual oil leakage phase angle is smaller than the oil leakage phase angle within the usable speed range. After the actual oil leakage ends, the valve follows the tappet and runs according to the cam profile.

[0058] The existing patent CN116557100B provides a valve mechanism performance curve as a function of engine speed, as shown in the figure. Figure 4 As shown in the figure, it can be seen that the valve closing angle is significantly different at different speeds; the valve closing angle advances at low speeds and lags at high speeds. The performance curve of the hydraulic variable valve mechanism provided in this embodiment as a function of speed is shown in the figure. Figure 5 As shown, the actual oil drain phase angle changes at different speeds, but the valve closing angle is basically the same at different speeds, which can meet the requirements of the late Miller cycle.

[0059] Example 2

[0060] This embodiment provides a method for operating a hydraulic variable valve mechanism for an engine, including the following:

[0061] When solenoid valve 22 is closed and slide valve 8 is not working, slide valve 8 cuts off the connection between the oil drain groove 5 of the housing and the opening, and valve 1 always works in the large opening state.

[0062] When the solenoid valve 22 opens and the slide valve 8 works, the slide valve 8 moves to another extreme position under the action of hydraulic oil. The oil drain groove 5 of the housing is connected to the opening. When the oil drain hole 6 moves to the position of the oil drain groove 5 of the housing, the oil drain hole 6, the oil drain groove 5 of the housing, the oil passage groove 9 of the slide valve, and the opening are all connected. The high pressure hydraulic oil is discharged through the slide valve 8 into the circumferential recess 10 of the transfer piston 11 and the first cavity 14, so that the valve works in a small opening state. The throttling buffer component 12 can perform reciprocating linear motion to adjust the communication area between the circumferential recess and the opening, so as to ensure that the valve is in a stable working state.

[0063] Cam 7 pushes tappet 4 upward, and hydraulic oil, via the high-pressure oil circuit, drives valve piston 2. Valve piston 2 opens valve 1, and tappet continues to move upward. Once tappet drain hole 6 connects with housing drain groove 5, the connection remains until tappet 4 reaches top dead center. Subsequently, tappet 4 descends until drain hole 6 disengages from housing drain groove 5. The corresponding phase angle is the high-pressure chamber's drainable phase angle. This only fulfills the first prerequisite for draining oil. A second condition is required for oil to drain to the transfer piston 11: the spool valve's oil passage 9 connects the oil circuit between housing drain groove 5 and transfer piston 11. When spool valve 8 descends and connects the oil circuit, the high-pressure chamber can discharge some high-pressure oil into the transfer piston chamber.

[0064] If the transfer piston 11 is not buffered during operation, it will cause seating impact and pressure wave oscillation. Therefore, the throttling buffer component installed in the transfer piston can effectively play a buffering role. When the high-pressure hydraulic oil flows from the drain hole at the tappet through the slide valve to the annular recess and the first cavity of the transfer piston, it will push the transfer piston downward. After the transfer piston descends to a certain height, it will gradually close the first oil passage until it is completely closed, thereby achieving the purpose of seating buffering by gradually reducing the flow area.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydraulic variable valve mechanism for an engine, comprising a housing that provides a tappet and a valve piston, the housing providing a lubricating oil passage, the housing forming a high-pressure oil passage between the tappet and the valve piston, the lubricating oil passage communicating with the high-pressure oil passage, the valve piston being movable along a piston chamber, characterized in that, The shell is provided with a slide valve and a distribution piston, the tappet side is provided with a drain hole, one end of the drain hole penetrates the top end of the tappet and communicates with a high-pressure oil passage, the shell is provided with a shell drain groove on the side of the tappet, the drain hole can communicate with the shell drain groove, the slide valve is provided with a slide valve oil passage in a ring shape, the shell is provided with an opening, when the slide valve works and during the movement of the tappet, the drain hole, the shell drain groove and the slide valve oil passage and the opening can all communicate, the distribution piston comprises a throttling buffer component, the throttling buffer component is provided with a ring-shaped recess for accommodating hydraulic oil, the ring-shaped recess can communicate with the opening, and the throttling buffer component can perform reciprocating linear motion to adjust the communication area of the ring-shaped recess and the opening.

2. The hydraulic variable valve mechanism for an engine according to claim 1, characterized by The throttling buffer component is hollow in part, and the throttling buffer component is provided with the ring-shaped recess in the middle section; The bottom of the throttling buffer component is provided with a spring seat, the spring seat is mounted on the shell, the spring seat is arranged outside the shell, an elastic element is arranged between the spring seat and the throttling buffer component, and one end of the spring seat is formed with a limiting step to limit one end of the throttling buffer component.

3. The hydraulic variable valve mechanism for an engine according to claim 2, characterized by One side of the throttling buffer component is provided with a first cavity, the first cavity communicates with the high-pressure oil passage, the first cavity communicates with the ring-shaped recess, and the other side of the throttling buffer component is provided with a second cavity, the second cavity is below the first cavity, and the elastic element is arranged between the second cavity and the spring seat to reset the throttling buffer component.

4. The hydraulic variable valve mechanism for an engine according to claim 1, characterized by The shell is provided with a first oil passage, an end of the first oil passage is the opening, the slide valve oil passage can communicate with the opening and the ring-shaped recess through the first oil passage, when the slide valve does not work, the first oil passage communicates with the lower side of the ring-shaped recess through the opening; The shell is further provided with a second oil passage, one end of the second oil passage communicates with the shell drain groove, and the other end of the second oil passage can communicate with the slide valve oil passage.

5. The hydraulic variable valve mechanism for an engine according to claim 4, characterized by The throttling buffer component is provided with a blocking part on one side of the ring-shaped recess, and the height of the blocking part is greater than the height of the first oil passage; When the throttling buffer component moves to the lower limit position, the blocking part completely blocks the opening.

6. The hydraulic variable valve mechanism for an engine according to claim 4, characterized by The height of the ring-shaped recess is less than the height of the first oil passage.

7. The hydraulic variable valve mechanism for an engine according to claim 3, characterized by The first cavity communicates with a pipeline, the pipeline communicates with the high-pressure oil passage through a second one-way valve, and a first one-way valve is arranged between the lubricating oil passage and the second one-way valve.

8. The hydraulic variable valve mechanism for an engine according to claim 1, characterized by The diameter of the drain hole is less than the height of the shell drain groove; When the drain hole communicates with the shell drain groove, the tappet moves to the vicinity of the top dead center of the tappet.

9. The hydraulic variable valve mechanism for an engine according to claim 1, characterized by The shell is provided with a control oil passage, the control oil passage is connected with the slide valve through an electromagnetic valve, and the electromagnetic valve is a normally closed electromagnetic valve.

10. The method of operating a hydraulic variable valve mechanism for an engine according to any one of claims 1 to 9, characterized by, The following contents are included: When the slide valve does not work, the slide valve cuts off the communication between the shell drain groove and the opening, and the valve always works in a large opening state; After the slide valve works, the slide valve moves to the other limit position under the action of oil pressure, the shell drain groove communicates with the opening, when the drain hole moves to the position of the shell drain groove, the drain hole, the shell drain groove and the slide valve oil passage and the opening all communicate, the hydraulic oil is discharged to the ring-shaped recess of the distribution piston through the slide valve, so that the valve works in a small opening state, the throttling buffer component can perform reciprocating linear motion to adjust the communication area of the ring-shaped recess and the opening, and the valve is kept in a stable working state.

Images