An in-cylinder braking mechanism for an engine, an engine, and a method

Abstract

The present invention belongs to the field of engine braking. To solve the problems existing in the engine braking process, an in-cylinder braking mechanism, an engine and a method for an engine are specifically disclosed, including a rocker arm body, a control valve, a piston, a stroke adjuster and an elastic member; the rocker arm body can swing around a rocker arm shaft configured thereon, and a braking oil passage is provided on the rocker arm shaft, and the braking oil passage is always in communication with the oil passage on the rocker arm body; the control valve, the piston and the stroke adjuster are installed at the power output end of the rocker arm body, and the control valve includes a first return spring, a check valve and a valve core; both the first return spring and the valve core are installed in the cavity of the rocker arm body, and the first return spring is installed at one end of the valve core to realize the return of the valve core; a check valve is installed in the valve core, and the check valve controls whether the braking oil passage is in communication with the high-pressure oil cavity of the piston; the piston extends or retracts relative to the rocker arm body under the action of the control valve.

Description

Technical Field

[0001] The present invention relates to the technical field of in-cylinder engine braking, and particularly to an in-cylinder engine braking mechanism, an engine and a method. Background Art

[0002] When a vehicle is going down a long slope, downshifting and using engine braking (in-cylinder braking) can reduce the use of brakes, and can avoid the problem that the brake pads get hot due to long-term braking, resulting in brake failure. In-cylinder braking uses the compression resistance generated during the compression stroke of the engine, internal friction and intake and exhaust resistance to form a braking effect on the driving wheels. The main principle is as follows: after releasing the accelerator pedal, when the piston is near the top dead center position during the compression stroke stage, the exhaust valve is instantaneously opened to release the high-pressure gas; after closing the exhaust valve, there is very little gas in the cylinder. When the piston moves from the top dead center to the bottom during the explosion (expansion) stage, the cylinder is in a negative pressure state. At this time, the gas will prevent the piston from moving downward (the piston is equivalent to evacuating), generating a torque acting in the opposite direction to the crankshaft, thereby generating a braking effect.

[0003] Most existing in-cylinder engine brakes are hydraulic telescopic types. During normal operation, the control solenoid valve is in a closed state, the length of the brake piston is short, and it cannot contact the valve tappet, so the braking function does not work. In the braking operation mode, the control solenoid valve is opened, and the brake piston extends under the action of oil pressure, pushing the valve tappet to further push the valve to open to achieve the braking function. However, this type of brake has many leakage points in the high-pressure oil chamber, a large leakage volume, especially more leakage at the threaded seal, and disadvantages such as poor lift consistency caused thereby. To solve this problem, a patent CN202310224165.6 discloses an in-cylinder engine braking mechanism and working method, which includes a rocker arm body that swings around its own configured rocker arm shaft. One end of the rocker arm body is a power input end, and the other end is a power output end. A piston chamber is provided at the power output end of the rocker arm body. It also includes a piston shaft, which is vertically fixedly installed in the piston chamber and extends outwards. A piston sleeve that axially expands and contracts under the action of hydraulic oil is installed at the lower end of the piston shaft for braking switching. A high-pressure oil chamber for accommodating hydraulic oil is provided inside the piston sleeve. The inside of the piston shaft is communicated with the high-pressure oil chamber and the braking oil passage on the rocker arm body. The piston shaft is threadedly connected to the piston chamber and the free rotation of the piston shaft is restricted by a fastening nut. The piston sleeve is composed of a piston inner sleeve fixedly installed at the bottom end of the piston shaft and a piston outer sleeve slidably sleeved on the piston inner sleeve. The high-pressure oil chamber is located between the piston inner sleeve and the piston outer sleeve. The inside of the piston inner sleeve is communicated with the high-pressure oil chamber and the inside of the piston shaft. A slide pin chamber, an oil inlet, and a check valve chamber are sequentially communicated from top to bottom inside the piston shaft. An oil inlet passage is provided on the side of the piston shaft. One end of the oil inlet passage is communicated with the braking oil passage on the rocker arm body, and the other end is communicated with the slide pin chamber and the check valve chamber. A slide pin is slidably provided in the slide pin chamber. The oil inlet passage is located below the slide pin. The top of the slide pin is connected to the inner wall of the piston shaft by a third return spring. A check valve mechanism for blocking the oil inlet is installed in the check valve chamber. The third return spring is used to push the check valve mechanism downward through the slide pin in the free state. The check valve mechanism is composed of a steel ball limit seat fixedly provided in the check valve chamber, a steel ball placed on the steel ball limit seat, and a fourth return spring located between the steel ball and the steel ball limit seat. The slide pin is used to push the steel ball.

[0004] However, the overall design of this structure is relatively complex. When switching from the braking state to the braking release state, there is a problem of long switching time. The reason is that the engine oil in the high-pressure oil chamber needs to be discharged through the check valve. On the one hand, the small flow area at the check valve will limit the discharge speed of the engine oil. On the other hand, the discharge of the engine oil will generate pressure, and the pressure acting on the check valve will cause the check valve to move in the closing direction, further reducing the flow area at the check valve. Therefore, at high speeds, there will be a situation where it cannot be switched in place within 1 cycle and it takes more than 3 cycles to be switched in place. Summary of the Invention

[0005] The object of the present invention is to provide an in-cylinder braking mechanism for an engine and an engine method to solve the problem of the switching speed of the existing hydraulic in-cylinder braking of the engine.

[0006] To achieve the above object, the present invention is solved by the following technical solutions:

[0007] In a first aspect, the present invention discloses an in-cylinder braking mechanism for an engine, including a rocker arm body, a control valve, a piston, a stroke adjuster and an elastic member;

[0008] The rocker arm body can swing around a rocker arm shaft configured thereon, and a braking oil passage is provided on the rocker arm shaft, and the braking oil passage is always in communication with the oil passage on the rocker arm body;

[0009] The control valve, the piston and the stroke adjuster are installed at the power output end of the rocker arm body. The control valve includes a first return spring, a one-way valve and a valve core; the first return spring and the valve core are both installed in the cavity of the rocker arm body, and the first return spring is installed at one end of the valve core to realize the return of the valve core; a one-way valve is installed in the valve core, and the one-way valve controls whether the braking oil passage is in communication with the high-pressure oil chamber of the piston;

[0010] The piston extends or retracts relative to the rocker arm body under the action of the control valve; and the end of the piston is connected to the end of the stroke adjuster through an elastic member.

[0011] As a further technical solution, a limiting device is provided at the end of the stroke adjuster, and a limiting shoulder surface cooperating with the limiting device is provided at the end of the piston.

[0012] As a further technical solution, one or more stroke adjusters are provided.

[0013] As a further technical solution, the axis of the stroke adjuster is parallel to the axis of the piston.

[0014] As a further technical solution, the elastic member is a leaf spring.

[0015] As a further technical solution, the piston is in sliding seal fit with the piston cavity on the rocker arm body.

[0016] As a further technical solution, an oil groove communicating with the high-pressure oil chamber of the piston is provided on the rocker arm body, and the oil groove is used to cooperate with the oil passage on the valve core.

[0017] As a further technical solution, the power output end of the rocker arm body is also connected to a spring support through a second return spring, and the spring support is pressed against the rocker arm shaft.

[0018] In a second aspect, based on the in-cylinder braking mechanism of the engine, the present invention also provides a braking method as follows:

[0019] In the non-braking working state, there is no pressure in the braking oil circuit. At this time, the control valve seats under the action of the first return spring, and the high-pressure oil chamber of the piston communicates with the outside; under the action of the elastic member, the piston moves upward to contact the bottom surface of the piston chamber, ensuring that the piston does not contact the valve push rod during the working process of the braking rocker arm body;

[0020] When the engine solenoid valve switches to the braking state, the braking oil circuit is filled with engine lubricating oil. The lubricating oil in the braking oil circuit enters the oil chamber, and then pushes the valve core upward until the valve core moves to the limit position. The engine oil passes through the oil chamber, the check valve, and the oil groove into the high-pressure oil chamber of the piston, and pushes the piston to move downward against the force of the elastic member until the piston contacts the stroke adjuster. The entire mechanism works in the braking state;

[0021] When braking needs to be released, the solenoid valve cuts off the braking oil circuit and opens the braking oil circuit to the outside. The pressure in the braking oil circuit decreases, and the valve core returns under the action of the first return spring. The high-pressure oil chamber of the piston communicates with the outside, and the piston retracts under the action of the elastic member, discharging the engine oil in the high-pressure oil chamber. At this time, during the swinging process of the rocker arm body, the piston never contacts the valve push rod, and the braking is released.

[0022] Thirdly, the present invention also provides an engine, which includes the in-cylinder braking mechanism of the engine described above.

[0023] The beneficial effects of the present invention are as follows:

[0024] By designing the specific structures of the control valve, the piston, and the stroke adjuster and their installation positions, the structure of the entire braking mechanism is simplified as a whole; and when the engine oil in the high-pressure chamber is discharged, it can be directly discharged to the outside without passing through the check valve, and there is no resistance in the middle. Therefore, the switching speed of the braking mechanism is fast, and it can ensure that the braking and non-braking states can be switched within 1 cycle at any rotational speed and can be switched in place, improving the switching speed when braking is released. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute a limitation to the present invention. It should also be understood that these drawings are shown for the purpose of simplification and clarity and are not necessarily drawn to scale. Now the present invention will be described and explained with additional features and details by using the drawings, wherein:

[0026] Figure 1 is a schematic diagram of the non-braking state of the in-cylinder braking mechanism in the embodiment of the present invention;

[0027] Figure 2Schematic diagram of the braking state of the in-cylinder braking mechanism in the embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the non-braking state of the control valve in the embodiment of the present invention;

[0029] Figure 4 Schematic diagram of the braking state of the control valve in the embodiment of the present invention;

[0030] Figure 5 Schematic diagram of the connection between the piston and the leaf spring in the embodiment of the present invention;

[0031] In the figure: 1, exhaust valve; 2, valve tappet; 3, valve bridge; 4, leaf spring; 5, rocker arm body; 6, piston; 61, high-pressure oil chamber; 7, control valve; 8, stroke adjuster; 9, fastening nut; 10, braking oil circuit; 11, spring support; 12, second return spring; 13, roller; 14, roller pin; 15, camshaft; 16, sliding bearing; 17, rocker arm shaft; 21, oil groove; 22, first return spring; 23, one-way valve; 24, valve core; 25, oil chamber. Detailed implementation manners

[0032] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention otherwise clearly indicates, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0034] As Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, the in-cylinder braking mechanism of the engine disclosed in this embodiment includes an exhaust valve 1, a valve tappet 2, a valve bridge 3, a leaf spring 4, a piston 6, a control valve 7, a stroke adjuster 8, a braking oil circuit 10, a camshaft 15, a rocker arm shaft 17, a first return spring 22, etc.;

[0035] Among them, the valve tappet 2 is installed on the valve bridge 3, the valve tappet 2 is connected to the exhaust valve 1, and the valve tappet 2 can move relative to the valve bridge 3 under the drive of the piston 6, thereby driving the exhaust valve 1 to move;

[0036] The rocker arm shaft 17 is installed inside the rocker arm body 5. The rocker arm body 5 can swing around the rocker arm shaft 17 configured on its own. One end is the power input end (see the right end of Figure 1 ), and the other end is the power output end (see the left end of Figure 1 );

[0037] At the power output end of the rocker arm body 5, there is a piston 6 that can extend. The piston 6 can expand and contract relative to the rocker arm body 5, and the piston 6 can achieve the purpose of brake switching through axial expansion and contraction. Specifically, when the piston 6 extends out of the rocker arm body 5, it contacts the valve tappet 2 and drives the exhaust valve 1 to move relative to the valve bridge 3 to a set position. When the piston 6 does not extend out of the rocker arm body 5, it does not contact the valve tappet 2. At this time, the exhaust valve 1 does not move. Further, the extension length of the piston 6 relative to the rocker arm body 5 is limited by the stroke adjuster 8. The stroke adjuster 8 is independent of the piston 6, is fixed on the rocker arm body 5, and is located on one side of the piston to limit the moving distance of the piston 6. A brake oil passage 10 is provided on the rocker arm shaft 17, and the brake oil passage 10 is always in communication with the oil passage on the rocker arm body 5. And whether the brake oil passage 10 is opened is controlled by a solenoid valve. When the engine needs to perform braking, the solenoid valve will switch to the braking state, and the brake oil passage 10 is filled with engine lubricating oil. When the engine does not need to perform braking, the solenoid valve will switch to the non-braking state, and at this time, the brake oil passage 10 is not filled with engine lubricating oil.

[0038] As in the Figure 1 shown braking mechanism, the rocker arm shaft 17 is fixed, and the rocker arm shaft 17 is connected to the rocker arm body 5 through a sliding bearing 16. A brake oil passage 10 is machined on it, and the brake oil passage 10 is always in communication with the oil passage on the rocker arm body 5.

[0039] Specifically, the structure of the input end of the rocker arm body 5 is described in detail. At the input end of the rocker arm body 5, a roller 13 is connected through a roller pin 14. The camshaft 15 drives the roller 13 on the rocker arm body 5. The camshaft 15 serves as the power input source of the rocker arm body 5 and drives the rocker arm body 5 to swing relative to the rocker arm shaft 17 through the roller 13.

[0040] Specifically, the structure of the output end of the rocker arm body 5 is described in detail. At the power output end of the rocker arm body 5, there are a piston 6, a control valve 7, and a stroke adjuster 8. And the axis of the piston 6 is perpendicular to the axis of the valve core 24 of the control valve 7. The movement of the piston 6 is controlled through the control valve 7. Further, the piston 6 controls the movement of the valve tappet 2, and the valve tappet 2 controls the movement of the exhaust valve 1. The stroke adjuster 8 is fixed on one side of the piston 6 to limit the moving distance of the piston 6.

[0041] Specifically, in this embodiment, the axis of the stroke adjuster 8 is parallel to the axis of the piston 6, and it is installed on one side of the piston 6 and the control valve 7; one end of the stroke adjuster 8 is installed on the rocker arm body 5 through a fastening nut 9, and the other end of the stroke adjuster 8 is connected to a leaf spring 4. The leaf spring 4 adopts a fork-shaped structure. One end of the leaf spring 4 is sleeved on the stroke adjuster 8 and can rotate around the stroke adjuster 8, and the other end of the leaf spring 4 is connected to the piston 6. The main function of the leaf spring 4 is to press the piston 6 tightly in the non-braking working state to prevent the piston 6 from contacting the valve push rod 2.

[0042] Further, a limit disc can be installed at the head position of the stroke adjuster 8 to limit the moving distance of the piston 6. A limit shoulder surface is provided on the piston 6. When the limit shoulder surface contacts the limit disc, it indicates that the piston 6 has moved to the specified position. Of course, it is not difficult to understand that the head position of the stroke adjuster 8 in this embodiment is not limited to the positioning disc structure, and can also be other structures such as a polygon structure, as long as it can play a limiting role. Further, the leaf spring 4 is sleeved on the stroke adjuster 8, sandwiched between two limit discs, and can rotate around the stroke adjuster 8.

[0043] Further, in this embodiment, the stroke adjuster 8 is a screw; it is not difficult to understand that in other embodiments, the stroke adjuster 8 can also be a limit pin or a limit portion is formed on the rocker arm body 5, etc.

[0044] Further, as Figure 5 shown is a schematic diagram of the piston 6 limit and the leaf spring 4 seen from below. The lower part of the stroke adjuster 8 adopts a large disc structure, and the large disc structure is used to limit the piston 6 and limit the extension length of the piston 6. The leaf spring 4 adopts a fork-shaped structure. The leaf spring 4 is sleeved on the stroke adjuster 8 and can rotate around the stroke adjuster 8.

[0045] Further, the control valve 7 includes an oil sump 21, a first return spring 22, a check valve 23, a valve core 24, and an oil chamber 25. The first return spring 22 and the valve core 24 are both installed in the cavity of the rocker arm body 5. The first return spring 22 is installed at one end of the valve core 24 to drive the valve core 24 to move along its axis. A check valve 23 is installed inside the valve core 24, and an oil passage is provided on the valve core 24. The main function of the check valve 23 is to control whether the high-pressure oil chamber 61 of the piston 6 is communicated with the brake oil passage 10. The oil sump 21 is provided on the rocker arm body 5. After the valve core 24 moves under the action of oil pressure, an oil chamber 25 is formed in the rocker arm body 5, where the oil chamber 25 is communicated with the brake oil passage 10, and the oil sump 21 is communicated with the high-pressure oil chamber 61 of the piston 6. When the check valve 23 is opened, the brake oil passage 10, the oil chamber 25, the oil sump 21, and the high-pressure oil chamber 61 are in a communicated state to realize the braking of the engine. When the check valve 23 is closed, the oil chamber 25 and the oil sump 21 are in a blocked state, and the engine is in a non-braking state. The braking structure of this embodiment reduces the leakage loss of the high-pressure oil chamber 61 and improves the consistency of each cylinder. At the same time, it improves the switching speed when the braking is released and ensures that the switching is completed within one cycle at any speed.

[0046] Further, the control valve 7 is arranged at the upper end of the high-pressure oil chamber 61 of the piston 6, and the valve core 24 of the control valve 7 can be arranged in the moving manner as shown in Figure 4 where the spring is on the top and the valve core 24 is on the bottom; it can also be designed in the moving manner where the spring is on the bottom and the valve core 24 is on the top, as long as the movement of the valve core 24 meets the oil passage connection requirements.

[0047] Further, the stroke adjuster 8 in this embodiment is not coaxially arranged with the piston 6, but the stroke adjuster 8 is arranged on one side of the piston 6. According to needs, the stroke adjuster 8 can be one or two.

[0048] Further, a second return spring 12 is also provided in this embodiment. The second return spring 12 is a tension spring. One end of the tension spring is connected to the in-cylinder braking mechanism body, and the other end is installed on the spring support 11. The spring support 11 is pressed against the rocker arm shaft 17. If space permits, a tension spring can be installed on each of the left and right sides of the rocker arm body 5, or the tension spring can be arranged above the braking mechanism body. The main purpose of setting the second return spring 12 in this embodiment is to pull the rocker arm body 5 to prevent the roller 13 of the rocker arm body 5 from disengaging from the camshaft 15.

[0049] Further, the piston 6 is in sliding seal fit with the piston chamber on the rocker arm body 5, and the axis of the piston chamber is perpendicular to the axis of the cavity where the control valve 7 is located.

[0050] Further, based on the above braking mechanism, this embodiment also provides a braking method, which is as follows:

[0051] Figure 1 As shown, it is the non-braking working state inside the engine cylinder. At this time, there is no pressure in the braking oil circuit 10. At this time, the valve core 24 of the control valve 7 seats under the action of the first return spring 22 (as Figure 3 shown). The high-pressure oil chamber 61 of the piston 6 is communicated with the outside; under the action of the leaf spring 4, the piston 6 moves upward and contacts the bottom surface of the piston chamber; it is ensured that the piston 6 will not contact the valve push rod 2 during the working process of the braking rocker arm body 5 (as Figure 1 shown).

[0052] When the solenoid valve of the engine switches to the braking state, the braking oil circuit 10 is filled with engine lubricating oil. As Figure 4 shown, under the action of the oil pressure, at this time, the lubricating oil in the braking oil circuit 10 enters the oil chamber 25, and then pushes the valve core 24 of the control valve 7 to move upward until the valve core 24 of the control valve 7 moves to the limit position. At this time, the engine lubricating oil enters the oil circuit of the valve core 24 of the control valve 7, and pushes the check valve 23 upward to open. Through the check valve 23, it enters the high-pressure oil chamber 61 of the piston 6 through the oil groove 21, and pushes the piston 6 to move downward against the acting force of the leaf spring 4 until the shoulder surface of the piston 6 contacts the stroke adjusting part 8. The whole mechanism works in the braking state;

[0053] When braking needs to be released, the solenoid valve of the engine will automatically cut off the braking oil circuit 10 and open the braking oil circuit 10 to the outside. The pressure in the braking oil circuit 10 decreases. The control valve 7 returns under the action of the first return spring 22. The high-pressure oil chamber 61 of the piston 6 is communicated with the outside. The piston 6 retracts under the action of the leaf spring 4, and discharges the engine oil in the high-pressure oil chamber 61. At this time, during the swinging process of the rocker arm body 5, the piston 6 never contacts the valve push rod 2, and the braking is released.

[0054] The extending length of the piston 6 relative to the rocker arm body 5 in this embodiment can be adjusted according to the need of the clearance to ensure that the clearance between the piston 6 and the valve push rod 2 meets the requirements in the braking state.

[0055] Furthermore, this embodiment also provides an engine, and the described engine uses the above braking mechanism and braking method for braking work.

[0056] Finally, it should also be noted that relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0057] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An engine cylinder brake mechanism, characterized in that: It includes a rocker arm body, a control valve, a piston, a stroke adjustment part and an elastic part; The rocker arm body can swing around the rocker arm shaft configured by itself, and a brake oil circuit is arranged on the rocker arm shaft, and the brake oil circuit is always connected with the oil circuit on the rocker arm body; The control valve, piston and stroke adjustment member are installed at the power output end of the rocker arm body. The control valve includes a first return spring, a one-way valve and a valve core. The first return spring and the valve core are both installed in the cavity of the rocker arm body. The first return spring is installed at one end of the valve core to realize the return of the valve core. A one-way valve is installed in the valve core to control whether the brake oil circuit is connected to the high-pressure oil chamber of the piston. The piston extends or retracts relative to the rocker arm under the action of the control valve; and the end of the piston is connected to the end of the stroke adjustment member through an elastic member; When the engine solenoid valve is switched to the braking state, the brake oil circuit is filled with engine lubricating oil, and the lubricating oil in the brake oil circuit enters the oil chamber, thereby pushing the valve core upward until the valve core moves to the limit position, and the engine oil enters the high-pressure oil chamber of the piston through the oil chamber, the one-way valve, and the oil groove, and pushes the piston to overcome the force of the elastic member and move downward until the piston contacts the stroke adjustment member, and the entire mechanism works in the braking state; When the brake needs to be released, the solenoid valve cuts off the brake oil circuit and opens the brake oil circuit to the outside world. The pressure in the brake oil circuit decreases, and the valve core returns under the action of the first return spring. The high-pressure oil chamber of the piston is connected to the outside world, and the piston retracts under the action of the elastic part to discharge the oil in the high-pressure oil chamber. At this time, during the swinging process of the rocker arm body, the piston never contacts the valve push rod, and the brake is released.

2. The engine cylinder brake mechanism according to claim 1, characterized in that: A limiting device is arranged at the end of the stroke adjusting member, and a limiting shoulder surface cooperating with the limiting device is arranged at the end of the piston.

3. The engine cylinder brake mechanism according to claim 2, characterized in that: The stroke adjusting member is provided with one or more.

4. The engine cylinder brake mechanism according to claim 1, characterized in that: The axis of the stroke adjusting member is parallel to the axis of the piston.

5. The engine cylinder brake mechanism according to claim 1, characterized in that: The elastic member is a leaf spring.

6. The engine cylinder brake mechanism according to claim 1, characterized in that: The piston is matched with the piston cavity on the rocker arm body in a sliding and sealing manner.

7. The engine cylinder brake mechanism according to claim 1, characterized in that: The rocker arm body is provided with an oil groove which is connected with the high-pressure oil chamber of the piston, and the oil groove is used to cooperate with the oil circuit on the valve core.

8. The engine cylinder brake mechanism according to claim 1, characterized in that: The power output end of the rocker arm body is also connected to the spring support through a second return spring, and the spring support is pressed against the rocker arm shaft.

9. A braking method for an engine cylinder brake mechanism according to any one of claims 1 to 8, characterized in that: as follows: In the non-braking working state, there is no pressure in the brake oil circuit. At this time, the control valve is seated under the action of the first return spring, and the high-pressure oil chamber of the piston is connected to the outside world; under the action of the elastic member, the piston moves up and contacts the bottom surface of the piston chamber, ensuring that the brake rocker body does not contact the valve push rod during the working process; When the engine solenoid valve is switched to the braking state, the brake oil circuit is filled with engine lubricating oil, and the lubricating oil in the brake oil circuit enters the oil chamber, thereby pushing the valve core upward until the valve core moves to the limit position, and the engine oil enters the high-pressure oil chamber of the piston through the oil chamber, the one-way valve, and the oil groove, and pushes the piston to overcome the force of the elastic member and move downward until the piston contacts the stroke adjustment member, and the entire mechanism works in the braking state; When the brake needs to be released, the solenoid valve cuts off the brake oil circuit and opens the brake oil circuit to the outside world. The pressure in the brake oil circuit decreases, and the valve core returns under the action of the first return spring. The high-pressure oil chamber of the piston is connected to the outside world, and the piston retracts under the action of the elastic part to discharge the oil in the high-pressure oil chamber. At this time, during the swinging process of the rocker arm body, the piston never contacts the valve push rod, and the brake is released.

10. An engine, characterized in that: It comprises the engine cylinder braking mechanism as described in any one of claims 1-8.

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