Engine hydraulic variable valve mechanism, engine and method

Abstract

The invention discloses an engine hydraulic variable valve mechanism, an engine and a method, and solves the problem that in the prior art, a piston and a tappet do not move synchronously, so that the valve closing angle is greatly changed along with the change of the rotating speed when a valve mechanism is partially opened. The hydraulic variable valve mechanism of the engine has the beneficial effect that the closing angle of the valve cannot be advanced along with the change of the rotating angle of the crankshaft at different rotating speeds, according to the specific scheme, an oil drainage hole is formed in the side, close to a piston, of a shell, the piston blocks the oil drainage hole, and the oil drainage hole can be communicated with a piston cavity in the moving process of the piston in the piston cavity; a slide valve is arranged at the oil drainage hole, is arranged between the tappet and the piston through the shell and can be communicated or disconnected with the low-pressure cavity, the control oil way is provided with a power-off normally-closed electromagnetic valve, the power-off normally-closed electromagnetic valve controls the slide valve, when the power-off normally-closed electromagnetic valve is powered off, the slide valve cuts off the high-pressure cavity and the low-pressure cavity, and when the power-off normally-closed electromagnetic valve is powered on, the high-pressure cavity is communicated with the low-pressure cavity. And the air valve is in a partial opening state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of variable valve technology, in particular to an engine hydraulic variable valve mechanism, an engine and a method. BACKGROUND

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

[0003] Miller cycle technology is a cycle mode that improves the thermal efficiency of an internal combustion engine by changing the intake valve closing angle to achieve an engine expansion ratio greater than the compression ratio. In the prior art, the intake valve closing angle earlier than the traditional intake valve closing angle is referred to as early Miller, and the intake valve closing angle later than the traditional intake valve closing angle is referred to as late Miller.

[0004] Two-stage variable valve mechanisms have emerged in response to this demand, using two opening degrees, large and small, to meet the needs of the engine. For early Miller cycle, a small valve opening degree is generally used at low speed and low load conditions to realize early Miller cycle of the engine to adapt to the needs of low load and low speed to achieve energy saving and emission reduction. The traditional valve opening degree is maintained at high speed and high load conditions. For engines using late Miller cycle, it is hoped that the large opening degree will be used for full load conditions, i.e. late Miller to achieve energy saving and emission reduction, and the small opening degree will maintain the traditional valve opening degree unchanged for acceleration and high speed cruising conditions.

[0005] Chinese patent application CN116557100B discloses an engine hydraulic variable valve mechanism and working method. The structure is to arrange a small oil leakage hole on one side of the tappet. Because the small oil leakage hole is arranged close to the tappet, and the tappet is driven by the cam, when the small oil leakage hole leaks oil, the high pressure cavity is in an open state, and the volume of the high pressure cavity will continuously decrease, so that the piston and the tappet are out of synchronization. The performance characteristics of this mechanism are that when the valve is at a small opening degree, the valve lift fluctuates greatly in a short time with the rotation of the camshaft, resulting in unstable working state of the valve at this time. In addition, the valve closing angle will change greatly with the change of speed, which is shown in the performance curve as Figure 4 indicated, i.e. the problem of this valve mechanism is that the valve closing phase angle will advance with the decrease of speed, and it is more suitable for engines using early Miller cycle. If used for late Miller cycle, the small opening degree will be too small for intake at low speed conditions, which is not conducive to acceleration. Finally, the overall valve structure also needs to improve the tappet, which needs to set a tappet groove in the tappet for oil leakage.

[0006] Chinese patent application CN117569888B provides an engine dynamic closed cylinder valve control mechanism, control method and engine, which is provided with an on-off valve arranged on the side of the piston. The on-off valve can discharge hydraulic oil from the high-pressure oil way to the low-pressure cavity to realize the dynamic closed cylinder function. It can only switch between the maximum opening degree and the completely closed state of the valve. The piston movement does not participate in the control, and it cannot realize two-stage variable opening degree of the valve.

[0007] Chinese patent application CN117345370B - an engine hydraulic three-stage variable valve control mechanism, engine and method, is upgraded from two-stage variable to three-stage variable based on Chinese patent CN116557100B. The performance curve of small opening degree also has the characteristics of valve closing angle change with speed change as shown in Figure 4

[0008] In summary, the existing variable valve control mechanism cannot meet the requirements of late Miller cycle for hydraulic variable valve mechanism. SUMMARY

[0009] In view of the deficiencies of the prior art, the purpose of the present application is to provide an engine hydraulic variable valve mechanism, which makes the valve working state more stable when the valve is in a partial opening degree state, and ensures the consistency of valve closing angle delay when the valve works at different speeds, and is suitable for late Miller cycle.

[0010] To achieve the above-mentioned purpose, the present application is realized by the following technical scheme: An engine hydraulic variable valve mechanism, comprising a housing, a tappet and a piston, the housing is provided with a rocker shaft, the rocker shaft is provided with a control oil way and a lubricating oil way, the housing forms a high-pressure cavity between the tappet and the piston, the piston can move along the piston cavity, the lubricating oil way can communicate with the low-pressure cavity through the high-pressure cavity, the housing is provided with a drain hole near the piston, the piston blocks the drain hole, the drain hole can communicate with the piston cavity during the movement of the piston in the piston cavity, a slide valve is arranged at the drain hole, the slide valve is arranged between the tappet and the piston through the housing, the slide valve can communicate with or disconnect from the low-pressure cavity, a de-energized normally closed electromagnetic valve is arranged on the control oil way, the de-energized normally closed electromagnetic valve controls the slide valve, when the de-energized normally closed electromagnetic valve is de-energized, the slide valve cuts off the high-pressure cavity and the low-pressure cavity, and the valve is in a full opening degree state; when the de-energized normally closed electromagnetic valve is energized, the high-pressure cavity and the low-pressure cavity are communicated, and the valve is in a partial opening degree state. With the action of the piston, the oil is discharged through the drain hole, the slide valve and the low-pressure cavity to ensure the relative stability of the valve working in the oil discharge process, and ensure the consistency of the valve closing angle delay when the valve works at different speeds.

[0011] ​An engine hydraulic variable valve mechanism as described above, when the valve is in a partial opening state, oil is discharged through the oil discharge hole, the spool valve and the low pressure cavity with the action of the piston to ensure the delay of the valve closing angle when working at different speeds and the consistency.

[0012] An engine hydraulic variable valve mechanism as described above, the distance between the spool valve and the piston is less than the distance between the spool valve and the piston, and the de-energized normally closed electromagnetic valve is connected with the vehicle control unit.

[0013] An engine hydraulic variable valve mechanism as described above, the distance between the upper side of the oil discharge hole and the high pressure oil passage is determined according to the amount of oil to be discharged.

[0014] An engine hydraulic variable valve mechanism as described above, the maximum stroke of the piston is greater than the sum of the distance between the upper side of the oil discharge hole and the high pressure oil passage and the diameter of the oil discharge hole.

[0015] An engine hydraulic variable valve mechanism as described above, the first one-way valve and the accumulator are sequentially arranged between the high pressure cavity and the spool valve, the second one-way valve is arranged between the high pressure cavity and the lubricating oil passage, the lubricating oil passage and the control oil passage are respectively connected with the oil tank through the oil pump, and the oil pump is connected with the controller.

[0016] An engine hydraulic variable valve mechanism as described above, the low pressure cavity is arranged in the housing, and the piston is connected with the valve.

[0017] An engine hydraulic variable valve mechanism as described above, the tappet cooperates with the cam.

[0018] In the second aspect, the application further provides an engine adopting the engine hydraulic variable valve mechanism.

[0019] In the third aspect, the application further provides a working method of the engine hydraulic variable valve mechanism, which comprises the following contents. When the tappet works, the spool valve cuts off the high pressure oil passage and the low pressure cavity when the de-energized normally closed electromagnetic valve is de-energized, and the valve is in a full opening state. When the de-energized normally closed electromagnetic valve is energized, the control spool valve is controlled to move, so that the high pressure cavity and the low pressure cavity are communicated, the valve is in a partial opening state, and oil is discharged through the oil discharge hole, the spool valve and the low pressure cavity with the continuous action of the piston to ensure the relative stability of the valve during the oil discharge process and the consistency of the delay of the valve closing angle when the valve works at different speeds.

[0020] The beneficial effects of the application are as follows: 1) The slide valve is arranged close to the piston in the present application, and the slide valve is communicated with the low pressure cavity through the oil leakage hole. When the valve is in the working state, the purpose of two-stage valve opening degree can be achieved by controlling the switch of the de-energized normally closed electromagnetic valve. When the de-energized normally closed electromagnetic valve is opened, the slide valve acts to make the high pressure cavity and the low pressure cavity communicated. After the piston runs to the set lift, the high pressure oil is discharged from the high pressure cavity to the low pressure cavity, and the valve is in the partial opening state. Because of the setting position of the oil leakage hole, the oil is discharged through the oil leakage hole, the slide valve and the low pressure cavity with the continuous action of the piston, so as to ensure the relative stability of the valve during the oil discharge process, and the valve is not greatly fluctuated by the movement of the tappet; Moreover, because of the reasonable setting position of the oil leakage hole, the pressure is discharged to the low pressure cavity through the oil leakage hole with the continuous action of the tappet. Thus, even at different speeds, the valve lift is basically located on the same curve except the fluctuation section, so as to ensure the stability of the valve at different speeds and the consistency of the valve closing angle delay, and the valve closing angle will not be advanced with the change of the crank angle at different speeds, the performance is relatively stable, and the use requirement of the late Miller cycle is met.

[0021] 2) The oil leakage hole is arranged between the slide valve and the low pressure cavity in the present application. During the running of the piston with the tappet, the oil leakage hole is opened. The maximum stroke of the piston is greater than the sum of the distance between the upper side of the oil leakage hole and the high pressure oil way and the diameter of the oil leakage hole. Thus, the oil discharge amount is consistent at different speeds, so as to ensure the consistency of the valve closing angle at different speeds. The valve closing angle can be adjusted by adjusting the distance between the upper side of the oil leakage hole and the high pressure oil way.

[0022] 3) The structure of the piston and the tappet does not need to be improved in the present application. Only the slide valve is arranged in the shell, and the slide valve is communicated with the low pressure cavity through the oil leakage hole. The structure is simple and reasonable. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0024] Figure 1 is a schematic diagram of the principle of an engine hydraulic variable valve mechanism according to one or more embodiments of the present application.

[0025] Figure 2 is a sectional view of an engine hydraulic variable valve mechanism according to one or more embodiments of the present application.

[0026] Figure 3 is a valve lift effect diagram of an engine hydraulic variable valve mechanism according to one or more embodiments of the present application.

[0027] Figure 4is the valve performance curve with speed change in the prior art Chinese patent application CN116557100B.

[0028] Figure 5 is the valve performance curve with speed change in an engine hydraulic variable valve mechanism according to one or more embodiments of the present application.

[0029] In the drawings: the mutual distance or size is exaggerated to show the position of each part, and the schematic diagram is only illustrative.

[0030] Wherein: 1, valve; 2, valve bridge; 3, piston; 4, housing; 5, rocker shaft; 6, tappet spring; 7, tappet; 8, spool; 9, camshaft; 10, first one-way valve; 11, second one-way valve; 12, accumulator; 13, high-pressure cavity; 14, de-energized normally closed electromagnetic valve; 15, oil pump; 41, oil drain hole; 42, high-pressure oil way; 51, control oil way; 52, lubricating oil way. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0032] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit exemplary embodiments according to the present application. As used herein, unless otherwise explicitly stated by the present application, the singular form is also intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, it means that there is a feature, step, operation, device, component and / or combination thereof; As introduced in the background, the motion of the piston and the tappet is not synchronized in the prior art, which causes the valve closing angle to change greatly with the speed change at partial opening of the valve mechanism. In order to solve the above technical problems, the present application proposes an engine hydraulic variable valve mechanism.

[0033] Example one In a typical embodiment of the present application, reference is made to Figure 1 and Figure 2As shown, an engine hydraulic variable valve mechanism includes a housing 4, a tappet and a piston, the housing is provided with a rocker shaft 5, the rocker shaft 5 is provided with a control oil way 51 and a lubricating oil way 52, the housing 4 forms a high pressure cavity between the tappet 7 and the piston 3, the piston 3 can move along the piston cavity, the lubricating oil way 52 can communicate with the low pressure cavity through the high pressure cavity, the housing 4 is provided with a drain hole 41 near the piston, the piston blocks the drain hole 41, the piston 3 can make the drain hole 41 communicate with the piston cavity during the movement of the piston cavity, a slide valve 8 is arranged at the drain hole, the slide valve 8 is arranged between the tappet 7 and the piston 3 through the housing 4, the slide valve 8 can communicate with or disconnect from the low pressure cavity, the high pressure cavity includes a high pressure oil way 42, the high pressure oil way 42 is arranged on the upper side of the drain hole 41, the control oil way 51 is provided with a de-energized normally closed electromagnetic valve 14, the de-energized normally closed electromagnetic valve 14 is connected with the slide valve 8, when the de-energized normally closed electromagnetic valve 14 is de-energized during the operation of the tappet 7, the slide valve 8 cuts off the high pressure oil way 42 from the low pressure cavity, the valve 1 is in a full opening state, when the de-energized normally closed electromagnetic valve is energized, the high pressure cavity communicates with the low pressure cavity, the valve 1 is in a partial opening state, when the piston 3 does not communicate with the drain hole, the high pressure cavity 13 is in a closed state, then the piston 3 and the tappet 7 will keep synchronous movement under the principle that the volume of the high pressure cavity is unchanged, with the continuous movement of the piston 3, the drain hole 41, the slide valve 8 and the low pressure cavity are used for draining oil, which ensures the consistency of the valve closing angle delay of the valve 1 under different rotating speeds.

[0034] Wherein, the distance between the slide valve 8 and the piston is less than the distance between the slide valve 8 and the tappet 7, the slide valve and the de-energized normally closed electromagnetic valve 14 are connected with a controller, the controller is a PLC controller or other types of controllers.

[0035] The housing 4 is provided with a drain hole 41 on the piston hole wall, which is used for controlling the oil drainage amount of the high pressure cavity to the low pressure cavity, and the amount of oil drainage can be adjusted by setting the height of the drain hole 41.

[0036] It should be noted that the drain hole 41 is directly opened on the housing 4 in the embodiment, but the scheme provided in the embodiment is also applicable to the structure with a piston sleeve.

[0037] Reference Figure 1 As shown, the first one-way valve 10 and the energy accumulator 12 are sequentially arranged between the high pressure cavity 13 and the slide valve 8, the second one-way valve 11 is arranged between the high pressure cavity 13 and the lubricating oil way 52, the lubricating oil way 52 and the control oil way 51 are respectively connected with an oil tank through an oil pump 15, the first one-way valve 10 and the second one-way valve 11 are used for supplementing the oil leakage loss in the high pressure cavity 13 at any time.

[0038] In the embodiment, the piston 3 is connected with the valve 1 through the valve bridge 2, the tappet 7 cooperates with the camshaft 9, and the tappet spring 6 is arranged at the tappet 7.

[0039] Camshaft 9 drives the tappet 7 up to produce high pressure oil, high pressure oil into the high pressure oil circuit 42 drive piston 3 movement, slide valve 8 and de-energized normally closed solenoid valve 14 control effect, de-energized normally closed solenoid valve 14 in the de-energized normally closed state, the slide valve is disconnected high pressure chamber and low pressure chamber, high pressure chamber 13 and low pressure chamber in the off state, at this time the valve 1 is in full open state, energized after de-energized normally closed solenoid valve 14 open, the slide valve 8 action makes the high pressure chamber 13 and low pressure chamber communication, piston 3 to the set lift, high pressure oil from the high pressure chamber 13 to the low pressure chamber, the valve 1 is in partial (small) opening state, with the piston continues to act through the oil drain hole 41, slide valve 8 and low pressure chamber for oil drain, so in the valve 1 is in working condition by controlling the switch of de-energized normally closed solenoid valve can realize two stage valve opening purpose.

[0040] Reference Figure 3 As shown, it is expected that the valve closing angle will not be advanced when the valve 1 is in small opening state, through the scheme provided by the embodiment is verified, reference Figure 1 As shown, the piston opening oil drain hole stroke is H1, at this time the oil in the high pressure chamber begins to drain from the oil drain hole 41, at this time the piston will have a process of high and low under the action of inertia force, and the amplitude of this high and low will be different with different speed, such as Figure 5 800 rpm, 1300 rpm, 1800 rpm in the example. Then although the tappet continues to go up, the piston will not follow up until the tappet runs to the top dead center, and then the piston goes down with the tappet, the piston goes up to block the oil drain hole, in the process of oil drain, because the position of the oil drain hole can effectively drain oil, so that the camshaft in the set working range to ensure the stability of the valve working, will not have too much high stroke; To ensure that the valve closing phase is consistent at different speeds, it is necessary to ensure that the high and low process at different speeds is completed before the tappet runs to the top dead center, the maximum stroke of the piston is H, H2=H-H1, H2 is the lost stroke of the piston, the maximum stroke position of the piston exceeds the lower side of the oil drain hole, H1 is the distance between the upper side of the oil drain hole and the high pressure oil circuit, that is, the piston drains the lost stroke H2 of the high pressure oil in each cycle, the consistency of the oil drain amount at different speeds ensures the consistency of the valve closing angle at different speeds, by adjusting the distance H1 between the upper side of the oil drain hole and the high pressure oil circuit, the valve closing angle can be adjusted.

[0041] Reference Figure 5 As shown, with the change of crank angle at different speeds, the valve lift in the middle section has certain fluctuation, but with the continuous change of crank angle, even at different speeds, the valve lift is located in the same curve, to ensure the stability and consistency of the valve working at different speeds, and the valve closing angle will not be advanced with the change of crank angle at different speeds, the performance is relatively stable, which can meet the demand of late Miller cycle.

[0042] The power-off normally closed electromagnetic valve 14 is a normally closed valve, and in the case of loss of electromagnetic valve adjustment function, the valve can be kept in the maximum opening state, and the normal operation of the engine is not affected.

[0043] Although the present example is a flat tappet, it is also applicable to a roller tappet structure.

[0044] Example Two The present example discloses an engine using the hydraulic variable valve train described in Example One.

[0045] Example Three The present example discloses a working method of an engine hydraulic variable valve train, comprising the following contents: Reference Figure 2 As shown, the camshaft 9 pushes the tappet 7 to move upward, the hydraulic oil enters the high-pressure oil way 42 and then pushes the piston 3 to move, the piston 3 pushes the valve bridge 2, and the valve bridge 2 pushes the two valves 1 to open.

[0046] The tappet 7 is communicated with the piston 3 through the high-pressure oil way, and the tappet and the spool valve are provided with a power-off normally closed electromagnetic valve, when the power-off normally closed electromagnetic valve is not powered, the spool valve cuts off the high-pressure oil way and the low-pressure cavity, and the valve always works in the large opening state.

[0047] When the power-off normally closed electromagnetic valve is powered, the power-off normally closed electromagnetic valve connects the control oil way and the spool valve, the spool valve 8 moves to the other limit position under the action of the oil pressure, and connects the high-pressure cavity and the low-pressure cavity, when the piston 3 moves to open the oil drain hole 41, the high-pressure oil is drained from the oil drain hole 41 to the low-pressure cavity through the spool valve, so that the valve works in the small opening state.

[0048] When the tappet descends, the power-off normally closed electromagnetic valve is powered off, the piston moves upward, and the oil drain hole 41 is closed, at this time, the high-pressure oil way is closed, and the piston continues to fall with the tappet 7 until the valve 1 is closed.

[0049] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydraulic variable valve mechanism for an engine, comprising a housing, tappets, and a piston, wherein the housing is provided with a rocker arm shaft, the rocker arm shaft is provided with a control oil passage and a lubrication oil passage, the housing forms a high-pressure chamber between the tappets and the piston, the piston is movable along the piston chamber, and the lubrication oil passage is connected to a low-pressure chamber through the high-pressure chamber, characterized in that, The housing has an oil drain hole on the side near the piston. The piston blocks the oil drain hole, and the oil drain hole can be connected to the piston chamber during piston chamber movement. A slide valve is installed at the oil drain hole, which is located between the tappet and the piston through the housing. The slide valve can be connected to or disconnected from the low-pressure chamber. The control oil circuit is equipped with a normally closed solenoid valve that controls the slide valve. During tappet operation, when the normally closed solenoid valve is de-energized, the slide valve cuts off the high-pressure chamber from the low-pressure chamber, and the valve is in a fully open state. When the normally closed solenoid valve is energized, the high-pressure chamber and the low-pressure chamber are connected, and the valve is in a partially open state. As the piston moves, oil is drained through the oil drain hole, the slide valve, and the low-pressure chamber to ensure the relative stability of valve operation during oil draining and to ensure the consistency of valve closing angle delay when the valve is operating at different speeds.

2. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, When the valve is partially open, oil is drained through the drain hole, slide valve and low-pressure chamber as the piston moves, so as to ensure the delayed valve closing angle when operating at different speeds.

3. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, The distance between the slide valve and the piston is less than the distance between the slide valve and the piston. The normally closed solenoid valve is connected to the vehicle control unit when the power is off.

4. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, The distance between the upper side of the drain hole and the high-pressure oil circuit is determined according to the amount of oil to be drained.

5. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, The maximum stroke of the piston is greater than the sum of the distance between the upper side of the drain hole and the high-pressure oil passage and the diameter of the drain hole.

6. The engine hydraulic variable valve mechanism according to claim 2, characterized in that, A first check valve and an accumulator are sequentially arranged between the high-pressure chamber and the slide valve, and a second check valve is arranged between the high-pressure chamber and the lubrication oil circuit. The lubrication oil circuit and the control oil circuit are respectively connected to the oil tank through an oil pump.

7. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, The low-pressure chamber is located inside the housing, and the piston is connected to the valve.

8. The engine hydraulic variable valve mechanism according to claim 1, characterized in that, The tappet engages with the cam.

9. An engine, characterized in that, The engine hydraulic variable valve mechanism according to any one of claims 1-8 is adopted.

10. A method for operating an engine hydraulic variable valve mechanism according to any one of claims 1-8, characterized in that, Includes the following: When the tappet is working, the normally closed solenoid valve is de-energized and the slide valve cuts off the high-pressure oil circuit and the low-pressure chamber, and the valve is in the fully open state. When the normally closed solenoid valve is energized, it controls the spool valve to operate, connecting the high-pressure chamber and the low-pressure chamber. The valve is in a partially open state. As the piston continues to move, oil is drained through the drain hole, the spool valve, and the low-pressure chamber. This ensures the relative stability of the valve operation during the oil draining process and the consistency of the valve closing angle delay when the valve operates at different speeds.

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