Gas distribution control method, control system and gas distribution apparatus

Abstract

This invention relates to the field of internal combustion engine technology and discloses a valve train control method, control system, and valve train device. The valve train control method includes acquiring the engine speed, determining that the engine is in an overspeed state based on the engine speed, preferentially cutting off the oil supply passage of the hydraulic clearance adjustment mechanism, and controlling the brake rocker arm to be in an active state, thus enabling in-cylinder braking. Throughout the overspeed braking condition, the hydraulic clearance adjustment mechanism remains in a non-supply state. Even if the exhaust valve clearance increases due to valve bridge tilt, it will not continuously fill with oil and extend, thereby avoiding overfilling that could cause the exhaust valve to fail to reliably seat, improving sealing reliability and engine operating stability during the transition between braking and normal operating conditions.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, and specifically to a valve train control method, control system, and valve train device. Background Technology

[0002] Internal combustion engines, especially diesel engines in heavy-duty commercial vehicles, typically incorporate in-cylinder braking devices to prevent excessive engine speed during downhill driving or towing without fuel. In existing technology, when the ECU detects that the engine speed has reached an overspeed threshold, it generally controls the oil control valve to supply oil to the brake rocker arm or in-cylinder brake, causing the braking mechanism to activate. At the end of the compression stroke, the exhaust valve opens, releasing compressed air energy as exhaust gas, thus creating additional braking force to prevent the engine speed from continuing to rise. Simultaneously, the engine's valve train often includes a hydraulic clearance adjustment mechanism to automatically compensate for the valve clearance between the camshaft and the valve mechanism through oil filling, thereby reducing noise and improving valve timing accuracy.

[0003] However, in engines that partially employ an exhaust valve bridge structure and are equipped with in-cylinder braking, the in-cylinder braking typically only opens one exhaust valve while keeping the other closed. This causes the valve bridge to tilt, resulting in additional clearance between the hydraulic clearance adjustment mechanism and the valve bridge. Under existing control strategies, when the ECU detects engine overspeed, it only controls the oil control valve to activate the in-cylinder brake; the hydraulic clearance adjustment mechanism remains connected to the engine's pressurized oil passages and maintains oil supply. When the in-cylinder brake continues to operate during overspeed, the hydraulic clearance adjustment mechanism repeatedly senses the "increased clearance" caused by the valve bridge tilt and, under oil pressure, continuously expands and fills with oil, easily leading to overfilling.

[0004] Once the overspeed condition is resolved, the ECU closes the cylinder brake, and the exhaust valve bridge returns to the state where both exhaust valves work together. However, at this time, due to the passive increase in the effective length, the hydraulic clearance adjustment mechanism often cannot fully retract within one working cycle, resulting in the exhaust valve not being able to fully sit down, causing problems such as poor valve sealing, abnormally high exhaust temperature, reduced engine power, or even burning of the exhaust valve. Summary of the Invention

[0005] The objective of this invention is to at least solve the problem of excessive oil filling in hydraulic clearance adjustment mechanisms under braking conditions. This objective is achieved through the following technical solution:

[0006] This invention proposes a gas distribution control method, comprising the following steps:

[0007] Get engine speed;

[0008] Based on the engine speed, it is determined that the engine is in an overspeed state, and the oil supply passage of the hydraulic clearance adjustment mechanism is cut off.

[0009] The control rocker arm is in an active state.

[0010] According to the valve timing control method of the present invention, when the engine enters the overspeed braking condition, the oil supply passage of the hydraulic clearance adjustment mechanism is cut off first from the control strategy, and then the brake rocker arm is controlled to be in the active state, thereby solving the problem that the hydraulic clearance adjustment mechanism is prone to overfilling oil under braking conditions.

[0011] Specifically, the engine speed is first acquired and compared with a preset speed threshold. When the engine speed is detected to be greater than the preset speed threshold, the control logic no longer simply activates the in-cylinder braking as in existing technologies. Instead, based on the condition that the engine speed exceeds the limit, it first controls the cutting off of the oil supply to the hydraulic clearance adjustment mechanism, isolating the hydraulic clearance adjustment mechanism from the pressure oil source and putting it into a no-oil-supply state. Subsequently, the brake rocker arm is activated, enabling the in-cylinder braking action to take effect. During the overspeed phase, the engine provides additional braking force through in-cylinder braking.

[0012] Throughout the braking process, the hydraulic clearance adjustment mechanism remains in a state where the oil supply passage is cut off. Although there may still be minor leaks inside the hydraulic clearance adjustment mechanism, and its effective length will slowly decrease, because it no longer receives a continuous supply of new oil from the pressure oil passage, the phenomenon of repeated oil filling and continuous elongation of the hydraulic clearance adjustment mechanism when the valve bridge tilts or the exhaust valve clearance increases, as seen in traditional solutions, will not occur. Therefore, even under overspeed braking conditions with prolonged valve bridge tilt and unilateral exhaust valve opening, the hydraulic clearance adjustment mechanism will not become overfilled due to continuous oil supply.

[0013] In addition, the gas distribution control method according to the present invention may also have the following additional technical features:

[0014] In some embodiments of the present invention, the step of controlling the brake rocker arm to be in an active state is followed by:

[0015] After a first preset time interval, the engine speed is acquired again;

[0016] Based on the engine speed, it is determined that the engine is not in an overspeed state, and the brake rocker arm is controlled to be in the closed state.

[0017] The oil supply passage is connected to the hydraulic clearance adjustment mechanism.

[0018] In some embodiments of the present invention, after the step of obtaining the engine speed again after a first preset time interval, the method further includes:

[0019] Based on the engine speed, it is determined that the engine is in an overspeed state, and the first preset time is greater than the preset time threshold, so the hydraulic clearance adjustment mechanism is replenished with oil.

[0020] In some embodiments of the present invention, the engine includes a plurality of cylinders, each cylinder being provided with at least one of the hydraulic clearance adjustment mechanisms, and the step of replenishing oil to the hydraulic clearance adjustment mechanism based on the engine speed determining that the engine is in an overspeed state and the first preset time is greater than a preset time threshold includes:

[0021] The plurality of cylinders are divided into a first cylinder group and a second cylinder group;

[0022] The hydraulic clearance adjustment mechanism of the first cylinder group replenishes oil;

[0023] After a second preset time interval, the oil supply passage of the hydraulic clearance adjustment mechanism of the first cylinder group is cut off, and the hydraulic clearance adjustment mechanism of the second cylinder group is replenished with oil.

[0024] In some embodiments of the present invention, after the step of cutting off the oil supply passage of the hydraulic clearance adjustment mechanism of the first cylinder group and replenishing oil to the hydraulic clearance adjustment mechanism of the second cylinder group after the second preset time interval, the method further includes:

[0025] The engine speed is obtained again;

[0026] Since the engine is still in an overspeed state, the hydraulic clearance adjustment mechanism of the first cylinder group is replenished with oil.

[0027] After the second preset time interval, the oil supply passage of the hydraulic clearance adjustment mechanism of the first cylinder group is cut off, and the hydraulic clearance adjustment mechanism of the second cylinder group is replenished with oil.

[0028] In some embodiments of the present invention, the step of cutting off the oil supply passage of the hydraulic clearance adjustment mechanism of the first cylinder group includes:

[0029] The oil supply passages of the hydraulic clearance adjustment mechanism of each cylinder in the first cylinder group are sequentially cut off.

[0030] In some embodiments of the present invention, the engine includes an exhaust rocker arm, the exhaust rocker arm having a control slide valve, and the step of cutting off the oil supply passage of the hydraulic clearance adjustment mechanism when the engine is in an overspeed state includes:

[0031] The control slide valve is switched from the second position to the first position. When the control slide valve is in the first position, the oil supply passage of the hydraulic clearance adjustment mechanism is in a connected state and the brake rocker arm is in a closed state. When the control slide valve is in the second position, the oil supply passage of the hydraulic clearance adjustment mechanism is in a cut-off state and the brake rocker arm is in an active state.

[0032] In some embodiments of the present invention, the engine further includes an oil control valve, and the step of controlling the control slide valve to switch from a second position to a first position includes:

[0033] The oil control valve is controlled to switch from the second working position to the first working position. When the oil control valve is in the first working position, the control slide valve is in the first position. When the oil control valve is in the second working position, the control slide valve is in the second position.

[0034] The present invention also proposes a control system, comprising:

[0035] processor;

[0036] The storage medium stores a computer program that, when executed by the processor, performs the gas distribution control method described above.

[0037] The present invention also proposes a gas distribution device, comprising:

[0038] The rocker arm shaft has a first control oil passage, a second control oil passage, and a pressure oil passage inside along its axial direction;

[0039] A brake rocker arm is pivotally connected to the rocker arm shaft and has a brake oil chamber communicating with the second control oil passage. A piston mechanism for performing braking actions is provided in the brake oil chamber.

[0040] An exhaust rocker arm is pivotally connected to the rocker arm shaft. A hydraulic clearance adjustment mechanism is provided on the exhaust rocker arm. A control slide valve is provided inside the exhaust rocker arm. An oil supply passage communicating with the oil supply port of the hydraulic clearance adjustment mechanism and a brake oil passage communicating with the second control oil passage are formed inside the exhaust rocker arm. The control slide valve is arranged to be movable between a first position and a second position. When the control slide valve is in the first position, the pressure oil passage is connected to the oil supply oil passage through the control slide valve, and the brake oil passage is connected to an external oil drain passage. When the control slide valve is in the second position, the first control oil passage is connected to the brake control oil passage through the control slide valve, and the oil supply oil passage is isolated from the pressure oil passage.

[0041] An oil control valve has a first working position and a second working position. When the oil control valve is in the first working position, the first control oil passage is connected to the oil drain passage. When the oil control valve is in the second working position, the first control oil passage is connected to the pressure oil passage.

[0042] The aforementioned control system is electrically connected to the oil control valve. Attached Figure Description

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0044] Figure 1 This is a first flowchart of the gas distribution control method according to an embodiment of the present invention;

[0045] Figure 2 This is a second flowchart of the gas distribution control method according to an embodiment of the present invention;

[0046] Figure 3 This is a third flowchart of the gas distribution control method according to an embodiment of the present invention;

[0047] Figure 4 A partial structural diagram of an engine according to an embodiment of the present invention is shown schematically;

[0048] Figure 5 for Figure 4 A magnified view of a section at point A in the middle;

[0049] Figure 6 A schematic block diagram of the hydraulic system of the valve train when the engine is in a non-braking condition, according to an embodiment of the present invention, is shown.

[0050] Figure 7 A schematic block diagram of the hydraulic system of the valve train when the engine is in braking condition according to an embodiment of the present invention is shown.

[0051] The attached figures are labeled as follows:

[0052] 10. Rocker arm shaft; 101. Oil supply port; 102. First control oil port; 103. Oil change port; 104. Second control oil port; 11. Pressure oil passage; 12. First control oil passage; 13. Second control oil passage; 14. Oil change passage; 15. Plug;

[0053] 20. Camshaft; 30. Exhaust rocker arm; 301. Control slide valve; 31. Oil supply passage; 32. Brake passage; 40. Brake rocker arm; 50. Intake rocker arm; 60. Oil control valve; 601. First oil port; 602. Second oil port; 70. Hydraulic clearance adjustment mechanism; 71. Oil supply port. Detailed Implementation

[0054] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0055] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0056] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0057] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations.

[0058] like Figures 4 to 7 As shown, before describing the valve timing control method of this application, a valve timing device provided by the present invention will be described first. This valve timing device is applied to an engine and includes components such as a rocker arm shaft 10 disposed on the cylinder head, a brake rocker arm 40 pivotally connected to the rocker arm shaft 10, and an exhaust rocker arm 30.

[0059] Along the axial direction of the rocker arm shaft 10, the interior of the rocker arm shaft 10 is provided with independent first control oil passage 12, second control oil passage 13, and pressure oil passage 11. The first control oil passage 12 provides control oil pressure to the control slide valve 301 within the exhaust rocker arm 30; the second control oil passage 13 supplies oil to the brake oil chamber within the brake rocker arm 40; and the pressure oil passage 11 supplies oil to the hydraulic clearance adjustment mechanism 70 on the exhaust rocker arm 30. Preferably, each oil passage is an axial oil hole extending along the axial direction of the rocker arm shaft 10, and is connected to the oil passage within the corresponding rocker arm via radial oil holes at the corresponding rocker arm positions.

[0060] In this embodiment, the brake rocker arm 40 is pivotally connected to the rocker arm shaft 10 in a rotatable manner. The brake rocker arm 40 is provided with a brake oil chamber communicating with the second control oil passage 13. The brake oil chamber houses a piston mechanism for performing braking actions, such as a piston and its return spring. The second control oil passage 13 is connected to the brake oil chamber of the brake rocker arm 40 via a radial oil hole on the rocker arm shaft 10. When pressure oil is built up in the second control oil passage 13, it can push the piston mechanism to move, thereby driving the brake rocker arm 40 to rotate around the rocker arm shaft 10, thereby achieving the braking and opening of the exhaust valve.

[0061] The exhaust rocker arm 30 is also pivotally connected to the rocker arm shaft 10. A hydraulic clearance adjustment mechanism 70 is provided on the exhaust rocker arm 30. The output end of the hydraulic clearance adjustment mechanism 70 abuts against the valve bridge or exhaust valve stem and is used to automatically compensate the valve train clearance under non-braking conditions. A control slide valve 301 for controlling the opening and closing of the oil circuit is provided inside the exhaust rocker arm 30. The control slide valve 301 is preferably a valve core type slide valve sleeved in the valve hole inside the exhaust rocker arm 30 and can move between a first position and a second position along its axial direction. Several oil passages that cooperate with the control slide valve 301 are also formed inside the exhaust rocker arm 30. One of them is an oil supply passage 31. One end of the oil supply passage 31 is connected to the oil supply port 71 of the hydraulic clearance adjustment mechanism 70, and the other end is arranged opposite to the pressure oil passage 11 through the valve hole. The other is the brake oil passage 32. One end of the brake oil passage 32 is connected to the second control oil passage 13 inside the rocker arm shaft 10, and the other end intersects with the circumferential side wall of the control slide valve 301 through the valve hole, so as to establish communication with the external oil drain passage or the first control oil passage 12 in different positions.

[0062] In the first operating condition of this embodiment, when the control slide valve 301 is in the first position, the pressure oil passage 11 is connected to the oil supply passage 31 via the control slide valve 301. The engine oil from the pressure oil passage 11 inside the rocker arm shaft 10 flows into the oil supply passage 31 through the control slide valve 301, and then enters the oil supply port 71 of the hydraulic clearance adjustment mechanism 70, thereby providing pressure oil to the hydraulic clearance adjustment mechanism 70 so that it can normally compensate the valve train clearance under non-braking conditions. At the same time, when the control slide valve 301 is in the first position, the brake oil passage 32 is connected to the external drain passage via the control slide valve 301, that is, the brake oil passage 32 is connected to the return oil passage. The oil in the second control oil passage 13 and the brake oil chamber connected thereto can be drained back to the oil pan through the brake oil passage 32 and the control slide valve 301, so that no effective braking pressure is built in the brake oil chamber, the brake rocker arm 40 does not move, and the engine is only driven by the exhaust rocker arm 30 to open and close the exhaust valve according to the exhaust cam.

[0063] In another operating condition, when the engine needs to perform in-cylinder braking, control oil pressure is established in the first control oil passage 12 through control elements such as the oil control valve 60. This control oil pressure acts on the control oil chamber at one end of the control slide valve 301, pushing the control slide valve 301 to move from the first position to the second position against the elastic force of the return spring. When the control slide valve 301 is in the second position, the flow path within the control slide valve 301 is switched, so that the first control oil passage 12 is connected to the brake oil passage 32 through the control slide valve 301. The pressurized oil from the first control oil passage 12 flows into the brake oil passage 32 through the control slide valve 301, and then enters the brake oil chamber of the brake rocker arm 40 through the second control oil passage 13, thereby pushing the piston mechanism in the brake oil chamber to move, driving the brake rocker arm 40 to perform the braking action, and realizing the in-cylinder braking function. Simultaneously, when the control valve 301 is in the second position, it blocks the connection between the pressure oil passage 11 and the oil supply passage 31. The oil supply passage 31 is isolated from the pressure oil passage 11, and the hydraulic clearance adjustment mechanism 70 no longer receives new pressure oil from the pressure oil passage 11. It only slowly leaks oil through a small internal leakage channel, preventing further oil filling and extension. This effectively avoids overfilling of the hydraulic clearance adjustment mechanism 70 under braking conditions. Through this structural arrangement, when the control valve 301 switches between the first and second positions, it ensures that the hydraulic clearance adjustment mechanism 70 normally compensates for the valve train clearance under non-braking conditions. Under in-cylinder braking conditions, it cuts off the oil supply to the hydraulic clearance adjustment mechanism 70 and provides brake oil pressure to the brake rocker arm 40, achieving a balance and coordination between the valve train clearance compensation function and the in-cylinder braking function.

[0064] In a preferred embodiment, the valve train further includes an oil control valve 60. The oil control valve 60 is a two-position three-way solenoid valve. The oil control valve 60 includes a valve body with a first oil port 601, a second oil port 602, and a third oil port, and a valve element housed within the valve body that can switch between a first operating position and a second operating position. The first oil port 601 formed on the valve body is connected to the engine's pressure oil passage 11 via an oil passage, for obtaining pressurized engine oil from the main oil passage of the engine lubrication system. The second oil port 602 is connected to a first control oil passage 12 via an oil passage, for supplying or releasing control oil to the first control oil passage 12. The third oil port is connected to the oil pan or other low-pressure return oil chamber via a return oil passage, for draining the oil in the first control oil passage 12.

[0065] Preferably, the valve is movably disposed within the valve body along its axial or radial direction, with one end cooperating with a return spring and the other end arranged opposite to the iron core of the electromagnetic coil. When the electromagnetic coil is de-energized, the valve remains in the first working position under the elastic force of the return spring. At this time, the valve connects the second oil port 602 with the third oil port. The first control oil passage 12 is connected to the third oil port via the second oil port 602 and the drain passage, thereby guiding the oil in the first control oil passage 12 back to the drain passage. The first control oil passage 12 is isolated from the first oil port 601 and is not connected to the pressure oil passage 11. No effective control oil pressure is established in the first control oil passage 12.

[0066] When braking is required, the electromagnetic coil is energized to generate electromagnetic attraction, overcoming the spring force of the return spring and pulling the valve to the second working position. In the second working position, the valve switches its internal flow path, connecting the second oil port 602 with the first oil port 601. The first control oil passage 12 connects to the first oil port 601 via the second oil port 602 and is also connected to the pressure oil passage 11, thereby introducing pressurized oil from the pressure oil passage 11 into the first control oil passage 12 to control the oil pressure of the control slide valve 301. At the same time, the second oil port 602 is isolated from the third oil port, and the first control oil passage 12 is no longer connected to the drain passage. Through the above structural arrangement, the oil control valve 60 can reliably switch between the pressure relief and pressure supply conditions under electrical signal control, achieving selective control of the oil pressure state of the first control oil passage 12, in order to cooperate with the control slide valve 301 to switch between the oil supply passage 31 and the braking passage 32.

[0067] In another embodiment, the oil control valve 60 is a switching valve that controls only whether the pressure oil passage 11 is connected to the first control oil passage 12. The oil control valve 60 is a two-position, two-way solenoid valve, which includes a valve body with a pressure port and a control port, and a valve element that can switch between a closed position and an open position. The pressure port is connected to the pressure oil passage 11 of the engine lubrication system through an oil passage, and the control port is connected to the first control oil passage 12 in the rocker arm shaft 10 through an oil passage.

[0068] When the solenoid coil is de-energized, the valve is in the closed position under the action of the return spring. At this time, the pressure port and the control port are separated, and the pressure oil passage 11 and the first control oil passage 12 are not connected. When the solenoid coil is energized, the valve overcomes the elastic force of the return spring and switches to the open position, so that the pressure port and the control port are connected, thereby introducing the press oil in the pressure oil passage 11 into the first control oil passage 12.

[0069] In order to achieve pressure relief of the first control oil passage 12, in this embodiment, an oil drain passage is provided at the end of the first control oil passage 12. For example, an oil drain hole is opened at the end or middle of the rocker arm shaft 10. The oil drain hole is connected to the return oil chamber or oil pan through the oil drain passage. A throttling hole or flow limiting hole can be provided in the middle to limit the oil drain flow. Thus, when the oil control valve 60 is in the open state, the pressure oil passage 11 supplies oil to the first control oil passage 12 through the oil control valve 60, and the control oil pressure is quickly established in the first control oil passage 12. The control oil enters the control oil chamber in the exhaust rocker arm 30 through the rocker arm shaft 10, pushing the valve core of the control slide valve 301 to switch from the first position to the second position, and supplies oil to the second control oil passage 13 through the aforementioned axial oil passage, the third oil groove and the oil change passage 14, realizing in-cylinder braking. When the oil control valve 60 is in the closed state, the connection between the pressure oil passage 11 and the first control oil passage 12 is cut off, and the first control oil passage 12 no longer receives pressure oil replenishment. The oil in it is slowly discharged back to the return oil chamber through the drain hole and the drain oil passage. The oil pressure in the first control oil passage 12 and the control oil chamber gradually decreases until it is lower than the elastic force of the return spring. The control slide valve 301 returns to the first position under the action of the return spring, the in-cylinder braking is released, and the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 reopens.

[0070] In a preferred embodiment, the control slide valve 301 includes a valve hole formed in the body of the exhaust rocker arm 30 and a valve core sleeved in the valve hole. Along the axial direction of the valve hole, the valve core is slidably arranged within the valve hole to reciprocate between a first position and a second position. One end of the valve hole forms a control oil chamber, which communicates with a first control oil passage 12 within the rocker arm shaft 10 via a first control branch oil passage. When control oil pressure is established in the first control oil passage 12, oil enters the control oil chamber and acts on the end face of the valve core, overcoming the elastic force of the return spring and pushing the valve core from the first position to the second position.

[0071] A return spring is installed at the end of the valve core furthest from the control oil chamber. One end of the return spring abuts against the valve core, and the other end abuts against the stepped surface or baffle of the valve hole. When the oil pressure in the first control oil passage 12 decreases or the oil control valve 60 switches to the first working position, the oil pressure in the control oil chamber is released, and the return spring pushes the valve core back to the first position, thereby keeping the control slide valve 301 in a state of communication between the oil supply passage 31 and the pressure oil passage 11 without the action of control oil pressure. Through the above structural arrangement, the control slide valve 301 can achieve reliable dual-position switching under the combined action of control oil pressure and return spring.

[0072] Furthermore, the outer peripheral wall of the valve core is provided with a first annular groove and a second annular groove at axial intervals. The first annular groove is mainly used to establish the connection between the pressure oil passage 11 and the oil supply oil passage 31 in the first position, and the second annular groove is mainly used to establish the connection between the first control oil passage 12 and the brake oil passage 32 in the second position.

[0073] Specifically, the valve core has an axial oil passage inside along its axial direction. One end of the axial oil passage opens into the control oil chamber, directly connecting to the oil in the control oil chamber. The other end connects to an opening on the outer peripheral wall of the valve core via a radial oil passage, i.e., to the second annular groove. Thus, when the first control oil passage 12 supplies oil to the control oil chamber, a portion of the pressurized oil entering the control oil chamber acts on the valve core end face, pushing the valve core from the first position to the second position and maintaining it in the second position. Simultaneously, it is also transported to the second annular groove via the axial oil passage, and further distributed to the brake oil passage 32 or the oil change hole 103 arranged opposite it, thereby achieving control oil pressure supply to the brake oil passage 32 when the valve core is in the second position. By setting an axial oil passage inside the valve core and connecting the control oil chamber to the second annular groove, control oil pressure can drive the valve core and supply oil to the brake oil circuit without adding additional external oil passages, resulting in a compact structure and a simpler oil circuit layout.

[0074] Specifically, multiple radial oil holes are arranged at different axial positions on the circumferential inner wall of the valve hole, respectively connecting to the pressure oil passage 11, the oil supply oil passage 31, the first control oil passage 12, and the brake oil passage 32 on the rocker arm shaft 10. When the valve core is in the first position, the axial position and width of the first annular groove are set to simultaneously cover the radial oil holes corresponding to the pressure oil passage 11 and the oil supply oil passage 31, thereby connecting the pressure oil passage 11 with the oil supply oil passage 31 through the first annular groove to supply oil to the hydraulic clearance adjustment mechanism 70. At the same time, the second annular groove is staggered from the radial oil hole corresponding to the brake oil passage 32 at this position, and the brake oil passage 32 is connected to the external oil drain passage only through other channels or throttle holes on the valve core, so that the second control oil passage 13 and the brake oil chamber are in a depressurized state.

[0075] When the valve core switches to the second position under the control oil pressure, the radial oil hole corresponding to the first annular groove and the oil supply passage 31 is misaligned, and the connection between the pressure oil passage 11 and the oil supply passage 31 is cut off, thereby cutting off the oil supply to the hydraulic clearance adjustment mechanism 70. At the same time, the second annular groove moves to a position aligned with the radial oil hole corresponding to the radial oil passage and the brake oil passage 32 of the valve core. The second annular groove is connected to the first control oil passage 12 and the brake oil passage 32 respectively, so that the pressure oil from the first control oil passage 12 flows into the brake oil passage 32 through the second annular groove, and enters the brake oil chamber of the brake rocker arm 40 through the second control oil passage 13, pushing the brake rocker arm 40 to perform the braking action. Through the cooperative arrangement of the first and second annular grooves, reliable switching between the oil supply path and the brake oil path can be achieved in different positions.

[0076] In some embodiments, the rocker arm shaft 10 has an oil supply hole 101 at a position corresponding to the exhaust rocker arm 30, which communicates with the pressure oil passage 11. The oil supply hole 101 is preferably a radial oil hole that penetrates the wall thickness of the rocker arm shaft 10 radially. An oil guide passage communicating with the valve hole is formed on the inner peripheral wall of the shaft hole of the exhaust rocker arm 30 at a circumferential position opposite to the oil supply hole 101, or the oil supply hole 101 is directly aligned radially with the area where the first annular groove is located.

[0077] When the valve core is in the first position, the oil supply port 101 and the first annular groove are radially opposite each other. Oil from the pressure oil passage 11 enters the first annular groove through the oil supply port 101, and then flows from the first annular groove to the oil supply passage 31, realizing the connection between the pressure oil passage 11 and the oil supply passage 31, and providing pressurized oil to the hydraulic clearance adjustment mechanism 70. Since the first annular groove is an annular groove structure, even if the exhaust rocker arm 30 rotates around the rocker arm shaft 10, the oil supply port 101 always faces the circumferential area where the first annular groove is located, thereby ensuring a stable and reliable oil supply relationship between the pressure oil passage 11 and the oil supply passage 31 during the swinging of the exhaust rocker arm 30.

[0078] In some embodiments, the rocker arm shaft 10 has a first control oil hole 102, an oil change hole 103, and a second control oil hole 104 at positions corresponding to the exhaust rocker arm 30 and the brake rocker arm 40. The first control oil hole 102 is used to introduce control oil from the first control oil passage 12 into the area where the control slide valve 301 is located. The second control oil hole 104 is used to introduce oil from the brake oil passage 32 into the second control oil passage 13 or to return oil from the second control oil passage 13 to the brake oil passage 32. The oil change hole 103 is connected to the second control oil hole 104 through the oil change oil passage 14 inside the rocker arm shaft 10, and is used to guide the control oil in the first control oil passage 12 to the second control oil passage 13 when the control slide valve 301 is in the second position.

[0079] Specifically, the first control oil hole 102 penetrates the wall thickness of the rocker arm shaft 10 radially and is radially opposite to the second annular groove on the outer periphery of the valve core. The other end of the first control oil hole 102 is connected to the first control oil passage 12. The oil change hole 103 is also a radial oil hole, with one end connected to the corresponding position on the inner wall of the valve hole, and the other end connected to the second control oil hole 104 through the oil change passage 14. The second control oil hole 104 is connected to the second control oil passage 13. When the valve core is in the second position, the axial position and width of the second annular groove are set to simultaneously cover the port of the radial oil passage and the port of the brake oil passage 32, so that the control oil in the first control oil passage 12 enters the second annular groove through the first control oil hole 102, then flows into the brake oil passage 32 from the second annular groove, and enters the second control oil passage 13 through the oil change hole 103 and the oil change passage 14, and finally enters the brake oil chamber of the brake rocker arm 40 to realize the oil supply drive of the brake rocker arm 40.

[0080] When the valve core is in the first position, the ports of the second annular groove and the radial oil passage and the brake oil passage 32 are staggered, thereby cutting off the connection between the first control oil passage 12 and the brake oil passage 32. The second control oil passage 13 can be connected to the external oil drain passage through the brake oil passage 32 and the oil drain passage in the control slide valve 301 to achieve pressure relief of the brake oil chamber. Through the arrangement of the first control oil hole 102, the oil change hole 103 and the second control oil hole 104 and their cooperating oil passages, after the valve core is switched to the second position, the first control oil passage 12 simultaneously undertakes the dual functions of pushing the valve core to change direction and supplying oil to the second control oil passage 13, resulting in a compact structure and clear oil circuit.

[0081] Furthermore, in order to ensure reliable communication between the oil holes and the internal oil passages and brake oil chambers of the respective rocker arms when the exhaust rocker arm 30 and the brake rocker arm 40 pivot around the rocker arm shaft 10 under the action of the camshaft 20, this embodiment provides oil groove structures that cooperate with the oil holes of the rocker arm shaft 10 on the inner peripheral walls of the shaft holes of the exhaust rocker arm 30 and the brake rocker arm 40, respectively.

[0082] Specifically, the exhaust rocker arm 30 is rotatably mounted on the rocker arm shaft 10 through its shaft hole. At least two oil grooves, a first oil groove and a second oil groove, are machined circumferentially on the inner circumferential wall of the shaft hole of the exhaust rocker arm 30. The first oil groove is axially aligned with the oil supply hole 101 on the rocker arm shaft 10 and is also connected to the oil supply passage 31 inside the exhaust rocker arm 30. The oil supply passage 31 is further connected to the oil supply port 71 of the hydraulic clearance adjustment mechanism 70, used to introduce the machine oil in the pressure oil passage 11 into the hydraulic clearance adjustment mechanism 70. The second oil groove is axially aligned with the first control oil hole 102 on the rocker arm shaft 10 and is connected to the control oil chamber of the exhaust rocker arm 30 and the valve hole where the control slide valve 301 is located. The arc length of each oil groove extending along the inner circumference of the shaft hole is greater than the maximum pivot angle of the exhaust rocker arm 30 during normal operation. This ensures that when the exhaust rocker arm 30 pivots around the rocker arm shaft 10, the openings of the oil supply hole 101 and the first control oil hole 102 always fall within the corresponding oil groove range. This ensures that the pressure oil passage 11 and the first control oil passage 12 enter the first oil groove and the second oil groove through the corresponding oil holes, and then are guided to the oil supply oil passage 31 and the control oil chamber inside the exhaust rocker arm 30 through the oil groove. The exhaust rocker arm 30 can maintain reliable communication with the relevant oil holes on the rocker arm shaft 10 throughout the entire pivoting process.

[0083] Furthermore, based on the above embodiment, a third oil groove is also machined circumferentially on the inner peripheral wall of the shaft hole of the exhaust rocker arm 30. The axial position of the third oil groove corresponds to the oil change hole 103 on the rocker arm shaft 10, such that the outer end of the oil change hole 103 opens into the third oil groove, and the inner end of the oil change hole 103 communicates with the oil change passage 14 provided inside the rocker arm shaft 10, and the oil change passage 14 is then connected to the second control oil passage 13.

[0084] During operation, after the oil control valve 60 switches from the pressure relief position to the pressure supply position, control oil pressure is established in the first control oil passage 12. The control oil first enters the second oil groove through the first control oil hole 102, and then enters the control oil chamber of the control slide valve 301 through the oil passage from the second oil groove, acting on the valve core end face and pushing the valve core to move from the first position to the second position.

[0085] When the valve core moves to the second position under the action of control oil pressure, the internal oil passage of the control slide valve 301 is opened, allowing the control oil in the second oil groove to be introduced into the third oil groove through the axial oil passage inside the valve core and the flow passage inside the exhaust rocker arm 30, thereby hydraulically connecting the first control oil passage 12 and the third oil groove. At this time, the control oil from the first control oil passage 12 continues to maintain the pressure of the control oil chamber through the second oil groove and the control branch oil passage, reliably holding the valve core in the second position. On the other hand, it flows into the oil change hole 103 through the third oil groove, and then sequentially enters the second control oil passage 13 through the oil change oil passage 14 and the second control oil hole 104 inside the rocker arm shaft 10. Finally, it is delivered to the brake oil chamber in the brake rocker arm 40 to drive the piston mechanism in the brake oil chamber and realize the drive of the brake rocker arm 40. By setting a third oil groove on the inner circumferential wall of the shaft hole of the exhaust rocker arm 30 and communicating with the oil change hole 103, the first control oil passage 12 can provide control oil pressure to the control slide valve 301 when the valve core is in the second position, and can also supply oil to the second control oil passage 13 through the third oil groove and the oil change oil passage 14. Thus, the control and braking oil supply functions are combined without adding an extra external oil circuit, resulting in a more compact structure and a simpler oil circuit.

[0086] The brake rocker arm 40 is also rotatably mounted on the rocker arm shaft 10 through its shaft hole. A groove is machined circumferentially on the inner wall of the shaft hole of the brake rocker arm 40 to mate with the second control oil hole 104 of the rocker arm shaft 10. This groove is axially aligned with the second control oil hole 104 on the rocker arm shaft 10, which communicates with the second control oil passage 13, and communicates with the brake oil chamber through a brake branch oil passage inside the brake rocker arm 40. Pressurized oil in the second control oil passage 13 flows into the groove within the shaft hole of the brake rocker arm 40 through the second control oil hole 104, and then enters the brake oil chamber through the brake branch oil passage, thus driving the piston mechanism within the brake oil chamber to swing the brake rocker arm 40 during braking. Similarly, the arc length of the oil groove extending along the inner circumference of the shaft hole is also greater than the maximum pivot angle of the brake rocker arm 40 during normal operation, so that the opening of the second control oil hole 104 is always within the range of the oil groove during the entire process of the brake rocker arm 40 pivoting around the rocker arm shaft 10, thereby ensuring that the hydraulic connection between the second control oil passage 13 and the brake oil chamber will not be interrupted due to the swing of the brake rocker arm 40.

[0087] With the above arrangement, even if the brake rocker arm 40 and the exhaust rocker arm 30 continue to pivot around the rocker arm shaft 10 under the drive of the camshaft 20, the pressure oil passage 11, the first control oil passage 12 and the second control oil passage 13 inside the rocker arm shaft 10 can still maintain stable communication with the control slide valve 301, the oil supply passage 31, the control oil chamber inside the exhaust rocker arm 30 and the brake oil chamber of the brake rocker arm 40 through the corresponding oil holes and the oil grooves on the inner peripheral wall of the shaft hole of each rocker arm, respectively. This ensures that the hydraulic clearance adjustment mechanism 70 and the brake rocker arm 40 can obtain reliable oil supply and discharge passages under various working conditions.

[0088] In some embodiments, the second control oil passage 13 can be designed as a closed oil passage arranged axially along the rocker arm shaft 10. That is, an axial blind hole extending inward from one end is machined inside the rocker arm shaft 10, and a sealed chamber is formed at the axial end of the blind hole. The blind hole is connected to the braking oil chamber of the braking rocker arm 40 through the second control oil hole 104. However, this type of blind hole closed oil passage has a large machining depth, requires high tool rigidity and coaxiality, is difficult to machine, and the dimensional accuracy and sealing of the end position are not easy to guarantee.

[0089] Therefore, in a preferred embodiment, the second control oil passage 13 adopts an axial oil passage structure that extends through the rocker arm shaft 10. Specifically, a through hole is drilled in the axial direction of the rocker arm shaft 10, penetrating the entire length of the rocker arm shaft 10. This through hole is connected to the oil groove in the shaft hole of the braking rocker arm 40 at the axial position corresponding to the braking rocker arm 40 through the second control oil hole 104. Subsequently, plugs 15 are installed at both ends of the through hole near the opening of the second control oil hole 104 and the braking rocker arm 40, respectively. For example, by means of press-fit metal plugs 15, threaded plugs 15, or welded sealing parts, the section of the through hole that does not need to be connected is closed. The second control oil hole 104 and the shaft hole of the braking rocker arm 40 are connected through this closed section, thus forming a closed second control oil passage 13 isolated from the outside in the middle section of the second control through hole. The above structure not only takes advantage of the simple processing technology and high positioning accuracy of through holes, but also achieves effective sealing of the second control oil passage 13 by setting plugs 15 at both ends or specific positions, reducing processing difficulty and cost. At the same time, it is convenient to set oil drain holes or inspection ports at the plugs 15, which improves the sealing reliability and maintenance convenience of the second control oil passage 13.

[0090] In some embodiments, the valve train further includes at least one intake rocker arm 50. The intake rocker arm 50 is rotatably mounted on the rocker arm shaft 10 through its shaft hole, preferably located on the intake side of the cylinder head. The intake rocker arm 50 includes an intake rocker arm 50 body, one end of which has a first actuating part for cooperating with the intake cam on the camshaft 20, such as a roller-type or sliding cam follower end, and the other end has a second actuating part for abutting against the intake valve assembly. The second actuating part can be a spherical push rod, a pressure head, or a support boss that cooperates with the valve bridge, so as to drive at least one intake valve to open and close according to a predetermined lift pattern when the intake cam rotates.

[0091] Preferably, the intake rocker arm 50 body is further provided with a clearance adjustment mechanism for adjusting the intake valve timing clearance, such as a threaded adjusting screw and locking nut structure. One end of the adjusting screw is connected to the second actuating part, and its end abuts against the intake valve stem end or valve bridge. The other end is threaded onto the intake rocker arm 50 body. By rotating the adjusting screw, the working clearance between the intake rocker arm 50 and the intake valve can be changed, thereby realizing the setting and compensation of the intake valve timing clearance. In other embodiments, the intake rocker arm 50 may also be provided with a hydraulic clearance adjustment mechanism 70, whose oil supply method can be connected to the existing pressure oil passage 11 of the engine. The specific structure can be a conventional design in the art and will not be described in detail here.

[0092] It should be understood that the first control oil hole 102 refers to the opening on the rocker arm shaft 10. The first control oil hole 102 can also refer to the hole in the exhaust rocker arm 30 that is connected to the control oil chamber. In essence, it is the port of an oil passage connecting the two ends of the rocker arm shaft 10 and the control oil chamber.

[0093] The present invention also provides an engine. The engine includes a cylinder block, a cylinder head, a crankshaft, a camshaft 20, and a valve train mounted on the cylinder head. Multiple cylinders are formed between the cylinder block and the cylinder head, arranged sequentially along the crankshaft axis. Each cylinder has at least one intake valve and at least one exhaust valve. At least one rocker arm shaft 10 is provided on the cylinder head, arranged longitudinally along the engine. A first control oil passage 12, a second control oil passage 13, and a pressure oil passage 11 are sequentially formed axially inside the rocker arm shaft 10. For each cylinder, a valve train is correspondingly provided on the cylinder head. This valve train includes an exhaust rocker arm 30, a brake rocker arm 40, and an intake rocker arm 50. The exhaust rocker arm 30 and the brake rocker arm 40 are pivotally connected to the rocker arm shaft 10 and cooperate with the exhaust valve assembly of that cylinder, used to drive the exhaust valve to open or perform in-cylinder braking under different operating conditions. The exhaust rocker arm 30 is equipped with a hydraulic clearance adjustment mechanism 70. A control slide valve 301 is arranged inside the exhaust rocker arm 30. An oil supply passage 31 connected to the oil supply port 71 of the hydraulic clearance adjustment mechanism 70 and a brake oil passage 32 connected to the second control oil passage 13 are formed inside the exhaust rocker arm 30. The control slide valve 301 can switch between a first position and a second position. It is used to connect the pressure oil passage 11 with the oil supply passage 31 and drain the brake oil passage 32 when the braking condition is not braking. When the braking condition is in the cylinder, it cuts off the connection between the pressure oil passage 11 and the oil supply passage 31 and connects the first control oil passage 12 with the second control oil passage 13 and the brake oil chamber of the brake rocker arm 40 through the brake oil passage 32. The engine may also include a control system electrically connected to the oil control valve 60 and sensors. The control system includes a processor and a storage medium storing a computer program. When the computer program is run by the processor, it executes the valve timing control method of the present invention, so that the engine can provide stable in-cylinder braking capability under overspeed and long-term braking conditions, while avoiding overfilling or loss of oil in the hydraulic clearance adjustment mechanism 70.

[0094] like Figure 1As shown, according to an embodiment of the present invention, a valve train control method is proposed. This valve train control method is applied to the aforementioned valve train device and includes the following steps: the control system acquires the engine speed in real time, determines that the engine is in an overspeed state based on the engine speed, and triggers overspeed protection control based on this speed condition. First, the control system switches the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 from a connected state to a cut-off state, so that the hydraulic clearance adjustment mechanism 70 is no longer connected to the engine pressure oil source, and only slowly loses oil through a small internal leak. Subsequently, the control system sends a braking activation command to the brake rocker arm 40 in the valve train device, so that the brake rocker arm 40 is in an activated state, and opens the exhaust valve at the end of the compression stroke to perform in-cylinder braking. Through the above steps, when the engine is in the overspeed range, the hydraulic clearance adjustment mechanism 70 is always in a cut-off state during the entire braking condition, thereby avoiding continuous oil filling and excessive extension of the hydraulic clearance adjustment mechanism 70 due to factors such as valve bridge tilt during in-cylinder braking.

[0095] Specifically, the steps for determining whether an engine is in an overspeed state based on engine speed include comparing the engine speed with a preset speed threshold. If the engine speed is continuously greater than the preset speed threshold for a certain period of time (such as 100ms or several control cycles), the engine is determined to be in an overspeed state. Conversely, if the engine speed is less than or equal to the preset speed threshold, the engine is determined to be in a non-overspeed state.

[0096] like Figure 2 As shown, further, based on the above embodiment, when the hydraulic clearance adjustment mechanism 70 oil supply passage 31 is cut off and the brake rocker arm 40 is activated according to the engine being in an overspeed state, the control system also performs overspeed exit and oil supply recovery control. Specifically, after cutting off the hydraulic clearance adjustment mechanism 70 oil supply passage 31, the control system starts timing. After a first preset time, the control system again obtains the current engine speed and determines whether it is in an overspeed state or a non-overspeed state.

[0097] When the engine is detected to be in a non-overspeed state, it is determined that the engine has exited the overspeed condition. The control system deactivates the brake rocker arm 40, disengaging the in-cylinder brake and returning the engine to its normal operating mode. Simultaneously, the control system switches the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 from a cut-off state back to an open state, reconnecting the hydraulic clearance adjustment mechanism 70 to the pressure oil source and restoring the normal automatic valve train clearance compensation function. By promptly releasing the in-cylinder brake and restoring the oil supply to the hydraulic clearance adjustment mechanism 70 after the overspeed condition is resolved, the engine can smoothly return to normal operating conditions after overspeed protection is completed.

[0098] like Figure 3As shown, further in the above embodiment, after the step of acquiring the engine speed again after a first preset time interval, the control system is also used to determine whether it is necessary to replenish the hydraulic clearance adjustment mechanism 70 with oil. Specifically, when the acquired engine speed still indicates that the engine is in an overspeed state, and the accumulated first preset time is greater than a preset time threshold, the control system determines that the engine has been in a braking state for a long time and the hydraulic clearance adjustment mechanism 70 may suffer a large loss of effective lift due to internal leakage if it has not been replenished with oil for a long time. At this time, the control system triggers the oil replenishment process of the hydraulic clearance adjustment mechanism 70.

[0099] In other words, the first preset time can be understood as the duration during which the engine is under in-cylinder braking and the oil supply to the hydraulic clearance adjustment mechanism 70 is cut off. When this time does not exceed the preset time threshold, it is considered that the internal leakage of the hydraulic clearance adjustment mechanism 70 has not reached the level requiring oil replenishment, and no oil replenishment is required. When the first preset time exceeds the preset time threshold and the engine is still in an overspeed or continuous braking state, the control system activates the oil replenishment strategy. Under the premise of maintaining the overall braking capacity of the engine, oil is replenished to the hydraulic clearance adjustment mechanism 70 by grouping out braking and briefly restoring oil supply.

[0100] Furthermore, in a preferred embodiment, the engine includes multiple cylinders, each corresponding to a hydraulic clearance adjustment mechanism 70. The control system employs a cylinder-group alternating oil replenishment strategy during the oil replenishment step. Specifically, the multiple cylinders are divided into a first cylinder group and a second cylinder group. For example, in a six-cylinder engine, the first cylinder group includes cylinders 1, 2, and 3, and the second cylinder group includes cylinders 4, 5, and 6. The oil supply passages 31 of each cylinder's hydraulic clearance adjustment mechanism 70 can be independently controlled to be cut off or connected.

[0101] When the engine is in an overspeed state and the first preset time exceeds the preset time threshold, requiring oil replenishment to the hydraulic clearance adjustment mechanism 70, the control system first performs oil replenishment for the first cylinder group. This involves deactivating the brake rocker arms 40 corresponding to each cylinder in the first cylinder group, temporarily disengaging the in-cylinder braking of the first cylinder group, and restoring the oil supply passages 31 of each hydraulic clearance adjustment mechanism 70 within the first cylinder group, allowing it to be supplied with oil again by the pressure oil source. Simultaneously, the second cylinder group maintains in-cylinder braking to ensure that the overall engine braking torque does not suddenly disappear. After the first cylinder group resumes oil supply, the control system starts timing from the start of oil replenishment. When the continuous oil replenishment time reaches the second preset time, it is considered that oil replenishment of the hydraulic clearance adjustment mechanism 70 in the first cylinder group is complete. At this point, the control system again cuts off the oil supply passages 31 of the hydraulic clearance adjustment mechanism 70 in the first cylinder group and restores braking to the first cylinder group.

[0102] Subsequently, the control system performs the same oil replenishment operation on the second cylinder group, controlling the brake rocker arm 40 of the second cylinder group to deactivate, temporarily disengaging the in-cylinder braking of the second cylinder group. Simultaneously, the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 of the second cylinder group is restored. After the same second preset time, the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 of the second cylinder group is cut off again, and braking is restored. Through this alternating control of replenishing oil to the first cylinder group first, and then to the second cylinder group, oil replenishment to the hydraulic clearance adjustment mechanism 70 of each cylinder can be completed while maintaining the overall in-cylinder braking state of the engine. This prevents excessive lift loss due to prolonged braking and avoids the momentary loss of braking for the entire engine.

[0103] Furthermore, based on the above-described cylinder group refueling implementation method, to cope with longer continuous braking conditions, the control system can continue to repeat the refueling cycle according to the engine speed and operating conditions after completing one refueling cycle. Specifically, after completing the refueling of the second cylinder group and restoring the oil supply passage 31 of its hydraulic clearance adjustment mechanism 70 to the cut-off state, the control system obtains the engine speed again. When it is determined that the engine is still in an overspeed state and the engine is still in the in-cylinder braking demand condition, the control system determines that it is necessary to refuel the hydraulic clearance adjustment mechanism 70 again.

[0104] At this point, the control system can repeat the above-mentioned oil replenishment process, again controlling the first cylinder group to disengage from braking and restore the oil supply passage 31 of the first cylinder group hydraulic clearance adjustment mechanism 70. After a second preset time interval, the oil supply passage 31 of the first cylinder group hydraulic clearance adjustment mechanism 70 is cut off and braking is restored. Then, the second cylinder group is controlled to disengage from braking and replenish oil, and after a second preset time interval, the oil supply to the second cylinder group is cut off and braking is restored. By periodically replenishing oil for each cylinder group hydraulic clearance adjustment mechanism 70 under long-term continuous braking conditions, the hydraulic clearance adjustment mechanism 70 can always be kept within a reasonable effective oil volume range, avoiding the gradual reduction of exhaust valve lift due to prolonged lack of oil replenishment. At the same time, it ensures that some cylinders are always in an in-cylinder braking state during the entire oil replenishment process to maintain the necessary braking effect.

[0105] Furthermore, during the aforementioned process of replenishing the first cylinder group, to reduce the instantaneous fluctuation of engine braking torque, the present invention can also employ a method of sequentially cutting off the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 for each cylinder in the first cylinder group. Specifically, taking cylinders 1 to 3 as the first cylinder group as an example, when replenishing the first cylinder group is required, the control system does not simultaneously disengage all cylinders 1 to 3 from braking, but controls them sequentially according to a preset order. For example, it first controls cylinder 1 to disengage from braking and restores its hydraulic clearance adjustment mechanism 70 oil supply, and then sequentially controls cylinders 2 and 3 to disengage from braking and restore oil supply. The replenishment time for each cylinder can be the same or different, and can be adjusted according to engine speed, load, and braking torque requirements.

[0106] Similarly, the same cylinder-by-cylinder switching method can be used when replenishing the second cylinder group, so that the number of cylinders that disengage in-cylinder braking and replenish the fuel at each moment is limited, thereby smoothly changing the braking torque throughout the replenishment process, further reducing the longitudinal acceleration fluctuation of the vehicle, and improving driving smoothness and comfort.

[0107] Furthermore, the valve train containing the hydraulic clearance adjustment mechanism 70 is equipped with a control valve 301. Whether the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 is cut off is determined by the valve position of the control valve 301. Specifically, the control valve 301 has a first position and a second position. When the control valve 301 is in the first position, the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 is connected to the pressure oil passage 11, and the hydraulic clearance adjustment mechanism 70 can be normally replenished by the pressure oil source. The brake rocker arm 40 is in the closed state, and the in-cylinder braking is not activated. When the control valve 301 is in the second position, the control valve 301 cuts off the connection between the pressure oil passage 11 and the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70, so that the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 is in the cut-off state. At the same time, it connects the first control oil passage 12 to the brake oil passage 32, so that the brake rocker arm 40 is in the activated state.

[0108] In this structure, the step of cutting off the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 when the engine is in an overspeed state can be specifically as follows: when the engine speed is detected to be greater than a preset speed threshold and this continues for a period of time, the control system provides control oil pressure or a control signal to the control slide valve 301, switching the control slide valve 301 from the first position to the second position, so that the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 changes from an open state to a closed state, and at the same time, the brake rocker arm 40 is activated to achieve in-cylinder braking. When the engine speed drops below the preset speed threshold and the exit condition is met, the control slide valve 301 is switched back from the second position to the first position, restoring the connection of the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 and closing the brake rocker arm 40.

[0109] Furthermore, the present invention provides an oil control valve 60 for pilot control of the valve position of the control slide valve 301. The oil control valve 60 is preferably a two-position two-way or two-position three-way solenoid valve, having a first working position and a second working position. Its pressure port is connected to the engine pressure oil passage 11, and its control port is connected to the first control oil passage 12. The first control oil passage 12 is then connected to the control oil chamber of the control slide valve 301 through the rocker arm shaft 10 and the internal oil passage of the exhaust rocker arm 30.

[0110] When the oil control valve 60 is in the first working position, it connects the first control oil passage 12 to the drain passage or suspends it. No effective control oil pressure is established in the first control oil passage 12, and the control slide valve 301 remains in the first position under the action of the return spring. At this time, the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 is connected, and the brake rocker arm 40 is closed. When the oil control valve 60 switches to the second working position, it connects the pressure oil passage 11 to the first control oil passage 12. Control oil pressure is established in the first control oil passage 12, and the control oil acts on the valve core of the control slide valve 301 through the control oil chamber, pushing the control slide valve 301 from the first position to the second position. This cuts off the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70, and activates the brake rocker arm 40.

[0111] Therefore, the step of controlling the oil control valve 60 to switch from the second working position to the first working position, where the control slide valve 301 is in the first position and in the second working position, where the control slide valve 301 is in the second position, can be implemented as follows: the control system sends an on or off control signal to the oil control valve 60 based on the engine speed and in-cylinder braking request. In the first working position, the oil control valve 60 does not supply pressure to the first control oil passage 12, and the control slide valve 301 remains in the first position under the action of the spring. In the second working position, pressure is supplied to the first control oil passage 12, and the control slide valve 301 switches to the second position under the control oil pressure, thereby realizing the automatic switching between the oil supply passage 31 of the hydraulic clearance adjustment mechanism 70 and the active state of the brake rocker arm 40.

[0112] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A gas distribution control method, characterized in that, This invention relates to a valve train, which includes a rocker arm shaft (10), a brake rocker arm (40), and an exhaust rocker arm (30). A first control oil passage (12), a second control oil passage (13), and a pressure oil passage (11) are provided internally along the axial direction of the rocker arm shaft (10). The brake rocker arm (40) is pivotally connected to the rocker arm shaft (10) and has a brake oil chamber communicating with the second control oil passage (13). The exhaust rocker arm (30) is pivotally connected to the rocker arm shaft (10). A hydraulic clearance adjustment mechanism (70) is provided on the exhaust rocker arm (30). A control slide valve (301) is provided inside the exhaust rocker arm (30), and an oil supply port (71) for the hydraulic clearance adjustment mechanism (70) is formed within the exhaust rocker arm (30). The valve (301) is connected to the oil supply passage (31) and the brake passage (32) is connected to the second control passage (13). The control valve (301) is arranged to be movable between a first position and a second position. When the control valve (301) is in the first position, the pressure passage (11) is connected to the oil supply passage (31) via the control valve (301) and the brake passage (32) is connected to an external drain passage. When the control valve (301) is in the second position, the first control passage (12) is connected to the brake passage (32) via the control valve (301) and the oil supply passage (31) is isolated from the pressure passage (11). The valve control method includes the following steps: Get engine speed; Based on the engine speed, it is determined that the engine is in an overspeed state, and the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) is cut off. The brake rocker arm (40) is controlled to be in an active state.

2. The gas distribution control method according to claim 1, characterized in that, The step of controlling the brake rocker arm (40) to be in the active state is further included by: After a first preset time interval, the engine speed is acquired again; Based on the engine speed, it is determined that the engine is in a non-overspeed state, and the brake rocker arm (40) is controlled to be in the closed state; The oil supply passage (31) is connected to the hydraulic clearance adjustment mechanism (70).

3. The gas distribution control method according to claim 2, characterized in that, After the step of obtaining the engine speed again after the first preset time interval, the method further includes: If the engine is determined to be in an overspeed state based on the engine speed and the first preset time is greater than the preset time threshold, the hydraulic clearance adjustment mechanism (70) is replenished with oil.

4. The gas distribution control method according to claim 3, characterized in that, The engine includes multiple cylinders, and each cylinder is provided with at least one hydraulic clearance adjustment mechanism (70). The step of replenishing oil to the hydraulic clearance adjustment mechanism (70) based on the engine speed determining that the engine is in an overspeed state and the first preset time is greater than a preset time threshold includes: The plurality of cylinders are divided into a first cylinder group and a second cylinder group; The hydraulic clearance adjustment mechanism (70) of the first cylinder group is replenished with oil; After a second preset time interval, the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) of the first cylinder group is cut off, and the hydraulic clearance adjustment mechanism (70) of the second cylinder group is replenished with oil.

5. The gas distribution control method according to claim 4, characterized in that, After the second preset time interval, the steps of cutting off the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) of the first cylinder group and replenishing the oil to the hydraulic clearance adjustment mechanism (70) of the second cylinder group further include: The engine speed is obtained again; Since the engine is still in an overspeed state, the hydraulic clearance adjustment mechanism (70) of the first cylinder group is replenished with oil; After the second preset time interval, the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) of the first cylinder group is cut off, and the hydraulic clearance adjustment mechanism (70) of the second cylinder group is replenished with oil.

6. The gas distribution control method according to claim 5, characterized in that, The step of cutting off the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) of the first cylinder group includes: The oil supply passages (31) of the hydraulic clearance adjustment mechanism (70) of each cylinder in the first cylinder group are cut off in sequence.

7. The gas distribution control method according to any one of claims 1 to 6, characterized in that, The engine includes an exhaust rocker arm (30), and the exhaust rocker arm (30) is provided with a control slide valve (301). The step of cutting off the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) when the engine is in an overspeed state includes: The control slide valve (301) is switched from a first position to a second position. When the control slide valve (301) is in the first position, the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) is in a connected state and the brake rocker arm (40) is in a closed state. When the control slide valve (301) is in the second position, the oil supply passage (31) of the hydraulic clearance adjustment mechanism (70) is in a cut-off state and the brake rocker arm (40) is in an active state.

8. The gas distribution control method according to claim 7, characterized in that, The engine also includes an oil control valve (60), and the step of controlling the control slide valve (301) to switch from a first position to a second position includes: The oil control valve (60) is controlled to switch from a first working position to a second working position. When the oil control valve (60) is in the first working position, the control slide valve (301) is in the first position. When the oil control valve (60) is in the second working position, the control slide valve (301) is in the second position.

9. A control system, characterized in that, include: processor; A storage medium storing a computer program that, when executed by the processor, performs the gas distribution control method according to any one of claims 1 to 8.

10. A gas distribution device, characterized in that, include: The rocker arm shaft (10) is provided with a first control oil passage (12), a second control oil passage (13) and a pressure oil passage (11) along the axial direction of the rocker arm shaft (10). A brake rocker arm (40) is pivotally connected to the rocker arm shaft (10) and has a brake oil chamber communicating with the second control oil passage (13). A piston mechanism for performing braking action is provided in the brake oil chamber. An exhaust rocker arm (30) is pivotally connected to the rocker arm shaft (10). A hydraulic clearance adjustment mechanism (70) is provided on the exhaust rocker arm (30). A control slide valve (301) is provided inside the exhaust rocker arm (30). An oil supply passage (31) communicating with the oil supply port (71) of the hydraulic clearance adjustment mechanism (70) and a brake passage (32) communicating with the second control oil passage (13) are formed inside the exhaust rocker arm (30). The control slide valve (301) is arranged to be able to operate in a first position and... The control slide valve (301) moves between two positions. When the control slide valve (301) is in the first position, the pressure oil passage (11) is connected to the oil supply passage (31) via the control slide valve (301) and the brake oil passage (32) is connected to the external drain passage. When the control slide valve (301) is in the second position, the first control oil passage (12) is connected to the brake oil passage (32) via the control slide valve (301) and the oil supply passage (31) is separated from the pressure oil passage (11). An oil control valve (60) has a first working position and a second working position. When the oil control valve (60) is in the first working position, the first control oil passage (12) is connected to the oil drain passage. When the oil control valve (60) is in the second working position, the first control oil passage (12) is connected to the pressure oil passage (11). The air distribution device further includes the control system as described in claim 9, wherein the control system is electrically connected to the oil control valve (60).

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