Brake mechanism in engine cylinder, engine and method

Abstract

The invention belongs to the field of engine braking, and particularly discloses an engine in-cylinder braking mechanism, an engine and a method in order to solve the problems existing in the engine braking process, and the engine in-cylinder braking mechanism comprises a rocker arm body, a control valve, a piston, a stroke adjusting piece and an elastic piece; the rocker arm body can swing around a rocker arm shaft arranged on the rocker arm body, a brake oil way is arranged on the rocker arm shaft, and the brake oil way is always communicated with an oil way on the rocker arm body. The control valve, the piston and the stroke adjusting piece are installed at the power output end of the rocker arm body. The control valve comprises a first return spring, a one-way valve and a valve element. The first return spring and the valve element are both installed in a cavity of the rocker arm body, and the first return spring is installed at one end of the valve element to achieve return of the valve element. A one-way valve is installed in the valve element and controls the brake oil way to be communicated with a high-pressure oil cavity of the piston or not. And 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 engine cylinder braking, and in particular to an engine cylinder braking mechanism, an engine and a method. Background Art

[0002] When the vehicle is going down a long slope, downshifting and using engine braking (in-cylinder braking) can reduce the use of brakes, avoid the problem of brake pad heating caused by long-term braking, and cause brake failure. In-cylinder braking uses the compression resistance generated by the compression stroke of the engine, and the internal friction and intake and exhaust resistance form a braking effect on the drive wheel. The main principle is: after releasing the accelerator, the exhaust valve opens instantly when the piston is near the top dead center during the compression stroke, releasing the high-pressure gas; when the exhaust valve is closed, there is very little gas in the cylinder. When the piston turns from the upper pole to run downward during the explosion (expansion) stage, the cylinder is in a negative pressure state. At this time, the gas will prevent the piston from going down (the piston is equivalent to vacuuming), generating a torque in the opposite direction of the crankshaft, thereby generating a braking effect.

[0003] Most of the existing engine cylinder brakes are hydraulic telescopic. During normal operation, the control solenoid valve is in a closed state, the brake piston is short, and it cannot contact the valve push rod, so the brake does not work. In the braking working mode, the control solenoid valve is opened, and the brake piston extends under the action of oil pressure, pushing the valve push rod to further push the valve to open to realize the braking function; however, this brake has many leakage points in the high-pressure oil chamber, large leakage, especially leakage at the threaded seal, and poor lift consistency caused by this. In order to solve this problem, patent CN202310224165.6 discloses an engine cylinder brake mechanism and working method, including a rocker body that swings around a rocker shaft configured by itself, one end of the rocker 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 body, and also includes a piston shaft, which is vertically fixed in the piston chamber and extends outward. The lower end of the piston shaft is equipped with a piston sleeve that is axially telescopic under the action of hydraulic oil for brake switching, and the interior of the piston sleeve is provided with a high-pressure oil chamber for accommodating hydraulic oil. The interior of the piston shaft is connected with the high-pressure oil chamber and the brake oil circuit on the rocker arm body. The piston shaft and the piston chamber are threadedly connected and the free rotation of the piston shaft is limited 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 sliding on the piston inner sleeve. The high-pressure oil chamber is located between the piston inner sleeve and the piston outer sleeve. The interior of the piston inner sleeve is connected with the high-pressure oil chamber and the interior of the piston shaft. The piston shaft is provided with a sliding pin chamber, an oil inlet and a one-way valve chamber which are connected in sequence from top to bottom. The side of the piston shaft is provided with an oil inlet channel, one end of which is connected to the piston on the rocker arm body. The brake oil circuit is connected, and the other end is connected with the sliding pin cavity and the one-way valve cavity. A sliding pin is slidably provided in the sliding pin cavity, and the oil inlet channel is located below the sliding pin. The top of the sliding pin is connected to the inner wall of the piston shaft through a third return spring. A one-way valve mechanism for blocking the oil inlet is installed in the one-way valve cavity. The third return spring is used to push the one-way valve mechanism downward through the sliding pin in a free state. The one-way valve mechanism consists of a steel ball limit seat fixed in the one-way valve cavity, 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 sliding pin is used to push the steel ball.

[0004] However, the overall design of the structure is relatively complex. When switching from the braking state to the brake release state, there is a problem of long switching time. The reason is that the oil in the high-pressure oil chamber needs to be discharged through the one-way valve. On the one hand, the small flow area at the one-way valve will limit the oil discharge speed. On the other hand, the oil discharge will generate pressure. The pressure on the one-way valve will cause the one-way valve to move in the closing direction, further reducing the flow area at the one-way valve. Therefore, at high speeds, there will be a situation where the switch cannot be completed within one cycle and it will take more than three cycles to switch to the right position. Summary of the invention

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

[0006] In order to achieve the above object, the present invention solves it through the following technical solutions: In a first aspect, the present invention discloses an engine cylinder brake mechanism, comprising a rocker arm body, a control valve, a piston, a stroke adjustment member and an elastic member; 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 body under the action of the control valve; and the end of the piston is connected to the end of the stroke adjusting member through an elastic member.

[0007] As a further technical solution, a limiting device is provided at the end of the stroke adjusting member, and a limiting shoulder surface cooperating with the limiting device is provided at the end of the piston.

[0008] As a further technical solution, one or more stroke adjustment members are provided.

[0009] As a further technical solution, the axis of the stroke adjustment member is parallel to the axis of the piston.

[0010] As a further technical solution, the elastic member is a leaf spring.

[0011] As a further technical solution, the piston is slidably sealed with the piston cavity on the rocker arm body.

[0012] As a further technical solution, an oil groove connected to 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 circuit on the valve core.

[0013] As a further technical solution, the power output end of the rocker arm body is also connected to a spring support via a second return spring, and the spring support is pressed against the rocker arm shaft.

[0014] In a second aspect, the present invention further provides a braking method based on the engine cylinder braking mechanism 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.

[0015] In a third aspect, the present invention further provides an engine, which includes the engine cylinder braking mechanism described above.

[0016] The beneficial effects of the present invention are as follows: The present invention simplifies the structure of the entire brake mechanism as a whole by designing the specific structures of the control valve, the piston and the stroke adjustment member and their installation positions; and when the engine oil in the high-pressure chamber is discharged, it can be discharged directly to the outside without passing through the one-way valve, without any resistance in the middle, so the switching speed of the brake mechanism is fast, and it can ensure that the switching between the braking and non-braking states can be achieved within one cycle at any speed, and it can be switched in place, thereby improving the switching speed when the brake is released. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute a limitation of the present invention. It should also be understood that these drawings are shown for simplicity and clarity and are not necessarily drawn to scale. The present invention will now be described and explained with additional features and details through the use of the accompanying drawings, in which: Figure 1 Schematic diagram of the non-braking state of the in-cylinder brake mechanism in an embodiment of the present invention; Figure 2 Schematic diagram of the braking state of the in-cylinder braking mechanism in an embodiment of the present invention; Figure 3 This is a schematic diagram of a control valve in a non-braking state in an embodiment of the present invention; Figure 4This is a schematic diagram of the braking state of the control valve in an embodiment of the present invention; Figure 5 A schematic diagram of the connection between the piston and the leaf spring in an embodiment of the present invention; In the figure: 1. exhaust valve; 2. valve push rod; 3. valve bridge; 4. leaf spring; 5. rocker arm body; 6. piston; 61. high-pressure oil chamber; 7. control valve; 8. stroke adjustment member; 9. fastening nut; 10. brake 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 DESCRIPTION

[0018] It should be noted that the following detailed descriptions are illustrative and 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 meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof; like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, the engine cylinder brake mechanism disclosed in this embodiment includes an exhaust valve 1, a valve push rod 2, a valve bridge 3, a leaf spring 4, a piston 6, a control valve 7, a stroke adjustment member 8, a brake oil circuit 10, a camshaft 15, a rocker arm shaft 17, a first return spring 22, etc.; The valve push rod 2 is installed on the valve bridge 3, and the valve push rod 2 is connected to the exhaust valve 1. The valve push rod 2 can move relative to the valve bridge 3 under the drive of the piston 6, thereby driving the exhaust valve 1 to move; The rocker shaft 17 is installed in the rocker body 5, and the rocker body 5 can swing around the rocker shaft 17 configured by itself, and one end is the power input end (see Figure 1 The other end is the power output end (see Figure 1 ); An extendable piston 6 is provided at the power output end of the rocker arm body 5. The piston 6 can be extended and retracted relative to the rocker arm body 5. The piston 6 can achieve the purpose of brake switching by axial extension and retraction. Specifically, when the piston 6 extends out of the rocker arm body 5, it contacts the valve push rod 2, driving the exhaust valve 1 to move to a set position relative to the valve bridge 3. When the piston 6 does not extend out of the rocker arm body 5, it does not contact the valve push rod 2. At this time, the exhaust valve 1 does not move. Furthermore, the extension length of the above-mentioned piston 6 relative to the rocker arm body 5 is limited by the stroke adjustment member 8, and the stroke adjustment member 8 is independent of the rocker arm body 5. In addition to the plug 6, it is fixed on the rocker body 5 and is located on one side of the piston to limit the moving distance of the piston 6; a brake oil circuit 10 is arranged on the rocker shaft 17, and the brake oil circuit 10 is always connected with the oil circuit on the rocker body 5; and whether the brake oil circuit 10 is opened is controlled by a solenoid valve. When the engine needs to brake, the solenoid valve will switch to the braking state, and the brake oil circuit 10 will be filled with engine lubricating oil; when the engine does not need to brake, the solenoid valve will switch to the non-braking state, and at this time the brake oil circuit 10 is not filled with engine lubricating oil.

[0020] like Figure 1 In the braking mechanism shown, the rocker shaft 17 is fixed, connected to the rocker body 5 through a sliding bearing 16, and a brake oil circuit 10 is processed on it. The brake oil circuit 10 is always connected with the oil circuit on the rocker body 5.

[0021] Specifically, the structure of the input end of the rocker arm body 5 is described in detail; the input end of the rocker arm body 5 is connected to the roller 13 through the roller pin 14, and 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; Specifically, the structure of the output end of the rocker arm body 5 is described in detail; a piston 6, a control valve 7 and a stroke adjustment member 8 are arranged at the power output end of the rocker arm body 5, and the axis of the piston 6 is perpendicular to the axis of the valve core 24 of the control valve 7, and the movement of the piston 6 is controlled by the control valve 7, and then the piston 6 controls the movement of the valve push rod 2, and the valve push rod 2 controls the movement of the exhaust valve 1; the stroke adjustment member 8 is fixed on one side of the piston 6 to limit the moving distance of the piston 6.

[0022] Specifically, in the present embodiment, the axis of the stroke adjusting member 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 adjusting member 8 is installed on the rocker arm body 5 through the fastening nut 9, and the other end of the stroke adjusting member 8 is connected to a leaf spring 4, and the leaf spring 4 adopts a fork-shaped structure, one end of the leaf spring 4 is mounted on the stroke adjusting member 8, and can rotate around the stroke adjusting member 8, and the other end of the leaf spring 4 is connected to the piston 6; the function of the leaf spring 4 is mainly to press the piston 6 in the non-braking working state to prevent the piston 6 from contacting the valve push rod 2.

[0023] Furthermore, a limit plate can be installed at the head position of the stroke adjustment member 8, and the limit plate limits 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 plate, 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 adjustment member 8 in this embodiment is not limited to the positioning plate structure, and can also be other structures such as polygonal structures, as long as it can play a limiting role. Furthermore, the leaf spring 4 is mounted on the stroke adjustment member 8, sandwiched between the two limit plates, and can rotate around the stroke adjustment member 8.

[0024] Furthermore, in the present embodiment, the stroke adjusting member 8 is a screw; it is not difficult to understand that in other embodiments, the stroke adjusting member 8 can also be a limit pin or a limit portion can be formed on the rocker arm body 5, etc.

[0025] Further, such as Figure 5 The figure shows a schematic diagram of the piston 6 limit and the leaf spring 4 as viewed from the bottom. The bottom of the stroke adjustment member 8 adopts a large disc structure, which is used to limit the piston 6 and restrict the extension length of the piston 6. The leaf spring 4 adopts a fork-shaped structure, and the leaf spring 4 is sleeved on the stroke adjustment member 8 and can rotate around the stroke adjustment member 8.

[0026] Furthermore, the control valve 7 includes an oil groove 21, a first return spring 22, a one-way 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, driving the valve core 24 to move along its axis, a one-way valve 23 is installed in the valve core 24, and an oil circuit is arranged on the valve core 24, the function of the one-way valve 23 is mainly to control whether the high-pressure oil chamber 61 of the piston 6 is connected with the brake oil circuit 10; the oil groove 21 is arranged on the rocker arm body 5; after the valve core 24 is moved by the oil pressure, it moves in the rocker arm body 5, wherein the oil chamber 25 is communicated with the brake oil circuit 10, and the oil groove 21 is communicated with the high-pressure oil chamber 61 of the piston 6; when the one-way valve 23 is opened, the brake oil circuit 10, the oil chamber 25, the oil groove 21, and the high-pressure oil chamber 61 are in a communicated state, and the engine braking is realized; when the one-way valve 23 is closed, the oil chamber 25 and the oil groove 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 the consistency of each cylinder is improved; at the same time, the switching speed when the brake is released is improved, and the switching is completed within one cycle at any speed.

[0027] Furthermore, 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 configured as follows: Figure 4As shown, the spring is on top and the valve core 24 is on the bottom. It can also be designed to be a spring on the bottom and the valve core 24 on the top, as long as the movement of the valve core 24 meets the oil circuit connection requirements.

[0028] Furthermore, the stroke adjustment member 8 in this embodiment is not coaxially arranged with the piston 6, but the stroke adjustment member 8 is arranged on one side of the piston 6. The stroke adjustment member 8 can be one or two as required.

[0029] Furthermore, the present embodiment is also provided with a second return spring 12, and the second return spring 12 is a tension spring, one end of the tension spring is connected to the brake mechanism body in the cylinder, and the other end is installed on the spring support 11, and the spring support 11 is pressed against the rocker arm shaft 17; if space permits, a tension spring can be installed on the left and right of the rocker arm body 5, or the tension spring can be arranged above the brake mechanism body; the purpose of providing the second return spring 12 in the present embodiment is mainly to pull the rocker arm body 5 to prevent the roller 13 of the rocker arm body 5 from disengaging from the camshaft 15.

[0030] Furthermore, the piston 6 is slidably sealed with the piston cavity on the rocker arm body 5, and the axis of the piston cavity is perpendicularly arranged to the axis of the cavity where the control valve 7 is located.

[0031] Furthermore, based on the above-mentioned braking mechanism, this embodiment also provides a braking method, which is specifically as follows: Figure 1 The figure shows the non-braking working state in the engine cylinder. At this time, there is no pressure in the brake oil circuit 10. At this time, the valve core 24 of the control valve 7 is seated under the action of the first return spring 22 (as shown in FIG. Figure 3 As shown in FIG. 1 ), the high-pressure oil chamber 61 of the piston 6 is connected to the outside; under the action of the leaf spring 4, the piston 6 moves upward and contacts the bottom surface of the piston chamber; ensuring that the brake rocker body 5 will not contact the valve push rod 2 during operation (such as Figure 1 as shown).

[0032] When the electromagnetic valve of the engine is switched to the braking state, the brake oil circuit 10 is filled with engine lubricating oil. Figure 4 As shown, under the action of oil pressure, at this time, the lubricating oil in the brake 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 lubricating oil of the engine enters the oil circuit of the valve core 24 of the control valve 7, and pushes the one-way valve 23 upward to open, and enters the high-pressure oil chamber 61 of the piston 6 through the one-way valve 23 and the oil groove 21, and pushes the piston 6 to overcome the force of the leaf spring 4 and move downward, until the shoulder surface of the piston 6 contacts the stroke adjustment member 8, and the whole mechanism works in the braking state; When the brake needs to be released, the solenoid valve of the engine will automatically cut off the brake oil circuit 10 and open the brake oil circuit 10 to the outside world. The pressure in the brake oil circuit 10 is reduced, and the control valve 7 returns to its position under the action of the first return spring 22. The high-pressure oil chamber 61 of the piston 6 is connected to the outside world. The piston 6 retracts under the action of the leaf spring 4 to discharge the 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 brake is released.

[0033] The extended 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, so as to ensure that the clearance between the piston 6 and the valve push rod 2 meets the requirement in the braking state.

[0034] Furthermore, this embodiment also provides an engine, which uses the above-mentioned braking mechanism and braking method to perform braking work.

[0035] Finally, it should be noted that relational terms such as first and second are merely used to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in 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 body under the action of the control valve; and the end of the piston is connected to the end of the stroke adjusting member through an elastic member.

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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