A high-efficiency multi-stage braking mechanism

Abstract

The present invention provides a high-efficiency multi-stage braking mechanism. The present invention includes a housing, a plunger sleeve arranged on the housing and fixed or reciprocating relative to the housing, a plunger arranged on the plunger sleeve and reciprocating relative to the plunger sleeve, and a hydraulic control unit. At least one first channel is arranged on the side wall of the plunger sleeve, and a locking body is arranged in the first channel and reciprocates relative to the first channel. The hydraulic control unit is connected to the second oil chamber formed between the plunger and the plunger sleeve, and is also connected to the first oil chamber formed between the plunger sleeve, the housing and the locking body. By adjusting the connection relationship between each oil chamber and the low-pressure source and the high-pressure source, the failure mode, the first effective mode and the second effective mode are realized. The mechanism is compact in size and high in reliability. It can replace a certain component of the original valve mechanism to meet the requirements of compact engine installation and use of the original valve mechanism components as much as possible, so as to realize multi-stage braking of the engine and extremely low-cost product upgrades, which is very conducive to product promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of variable valve timing mechanisms of engines, and in particular to a high-efficiency multi-stage braking mechanism. Background Art

[0002] With the development of energy-saving and emission-reduction technologies for vehicles, the braking capacity of the vehicle itself has decreased; and with the increase in vehicle load and speed, the demand for braking power has increased, which requires the braking system to provide greater braking power. Since the main braking system and the retarder installed on the vehicle transmission system are prone to thermal decay after long-term operation, the braking power is rapidly reduced or even brake failure, and the life of the braking system is greatly reduced. In this context, engine braking without thermal decay problems has become one of the key technologies for vehicle braking.

[0003] Improving engine braking power and variable valve train reliability are the main challenges of engine braking. In particular, engine braking is not only needed for large commercial vehicles equipped with large-displacement engines, but is also gradually needed for small and medium-sized commercial vehicles equipped with small-displacement engines and large hybrid commercial vehicles. At the same speed, engine braking power decreases significantly as engine displacement decreases. Therefore, further improving engine decompression braking performance, especially developing two-stroke braking, has become inevitable.

[0004] Both four-stroke decompression brake and two-stroke brake (hereinafter referred to as brake unless otherwise specified) rely heavily on the development of variable valve trains and must meet the following requirements at the same time:

[0005] (1) It can be arranged within the given engine dimensions (i.e., without increasing the length, width, and height of the engine), minimize changes to the engine, and use the original engine valve train components as much as possible to achieve low-cost product upgrades.

[0006] (2) Able to operate reliably and switch quickly within the speed range required by the engine.

[0007] (3) Able to provide the valve lift curve required for optimal engine performance.

[0008] (4) Increase the number of braking levels to cover as wide a range of braking conditions as possible.

[0009] The four-stroke decompression brake does not need to change the original engine valve mechanism, and an additional brake transmission chain is set for the brake exhaust valve; while the two-stroke brake needs to set the intake / exhaust drive transmission chain and the intake / exhaust brake transmission chain, and the engine operation mode is switched by controlling the working state of the above-mentioned drive mechanism and brake mechanism. Among them, the above-mentioned brake transmission chain is a transmission chain from the brake cam to the brake valve including the brake mechanism, and the working state of the brake mechanism determines the working state of the transmission chain; the above-mentioned drive transmission chain is a transmission chain from the drive cam to the drive valve including the drive mechanism, and the working state of the drive mechanism determines the working state of the transmission chain.

[0010] After extensive research, the inventors found that the development of a variable valve train required for engine braking is more difficult than that of a conventional variable valve train. The difficulty mainly lies in the development of the brake mechanism, especially the brake mechanism on the exhaust side. This is because:

[0011] (1) Since the maximum braking speed of the engine is much higher than the rated speed, especially for small-displacement engines, excessively high braking speed will cause the pure hydraulic brake mechanism to fail to work properly due to reasons such as pump lift.

[0012] (2) In braking mode, the cylinder pressure at the compression top dead center or near each top dead center is very high and fluctuates violently. The brake mechanism needs to overcome a very large and high-frequency changing gas force to open the valve. At the same time, the cylinder pressure increases with the increase in speed. The engine braking speed is extremely high, the stress condition of the brake mechanism is very severe, and the failure rate of related components is very high. Therefore, its reliability design is a difficult problem in the industry.

[0013] (3) The two-stroke exhaust brake cam has multiple lobes, and its base circle segments are dispersed. The phase zone of the largest base circle segment is much shorter than that of the traditional variable valve mechanism; and the engine braking speed is extremely high. Therefore, the brake mechanism needs to have an extremely high switching response speed to achieve a quick and smooth switch to the braking mode in a wider speed range to increase the proportion of engine braking, thereby reducing the frequency and intensity of use of the main brake system, increasing its service life, and reducing dust pollution from the friction brake system.

[0014] (4) In order to maximize the effect of engine braking under different load weights, slopes, slope lengths, etc., it is necessary to increase the maximum braking power output as much as possible and achieve multi-level braking.

[0015] The inventor has conducted extensive research and comparative analysis on existing brake mechanisms and their application effects on engines, and discovered the advantages and problems to be solved of existing brake mechanisms:

[0016] (1) Pure hydraulic brake mechanism: It adopts a master-slave piston structure, which has the following advantages: (a) The maximum cylinder pressure is low, the brake mechanism is subjected to less force, and it has a hydraulic buffer function, so the brake mechanism is highly reliable. (b) The segment switching does not affect the reliability of the brake mechanism structure. The existing problems are: (a) The pressure in the cylinder near the top dead center is very high, resulting in a serious lift loss in the valve lift curve generated by the mechanism, that is, the valve cannot maintain a large lift, resulting in a significant reduction in braking power and a rapid increase in the maximum cylinder pressure in the high-speed braking area. (b) Pump-up phenomenon occurs at high speeds, resulting in serious accidents such as excessive pressure in the hydraulic oil chamber and collision between the valve and the piston. (c) The operating speed range is limited by many factors such as the collision between the valve and the piston and the pump-up effect, and can only work within a limited speed range. (d) The lift of the exhaust brake cam near the top dead center is limited, and a larger cam cannot be used, and thus a higher braking power output cannot be obtained.

[0017] (2) Pure mechanical brake mechanism: It adopts a mechanical locking structure. The advantage is that the valve lift is not affected by the pressure in the cylinder. Compared with the pure hydraulic brake mechanism, the braking power is higher. The problems are: (a) The maximum cylinder pressure is high and the brake mechanism is subjected to large force. (b) The impact force on the brake mechanism is very large, especially when the pressure in the engine cylinder changes drastically, and the related parts are very easy to be damaged. (c) The switching can only be carried out within the base circle segment of the brake cam. As the speed increases, the difficulty of completing the switching at one time increases, especially during two-stroke braking; the segmented switching will further significantly reduce the reliability of the pure mechanical brake mechanism. This is because when the locking pin is in the middle state of the switching, the contact surface between the locking pin and the locked body is smaller than the contact surface when the switching is complete. In this case, opening and closing the valve will cause the contact stress between the locking pin and the locked body to increase significantly, especially near the top dead center. These aspects have led to a high failure rate of the pure mechanical brake mechanism.

[0018] (3) Composite braking mechanism: As disclosed in the "Integrated Lost Rocker Brake System with Automatic Reset" with application number 201390000921.7, the internal plunger can slide up and down in the vertical hole in the drive piston. The internal plunger has an annular groove structure or an inclined surface structure, and its shape is suitable for accommodating one or more wedges, rollers or spherical locking elements. The outer wall of the drive piston assembly also has one or more grooves that can accommodate one or more of the above-mentioned locking elements. When braking is required, high-pressure hydraulic oil drives the drive piston and the internal plunger to overcome the preload of the drive piston spring and the internal plunger spring and separate; when the internal plunger is fully displaced, the internal plunger will drive the above-mentioned locking element to enter one or more grooves in the wall of the drive piston assembly, thereby mechanically locking the brake piston in the rocker arm. When braking is not needed, the hydraulic pressure is removed, the internal plunger spring first pushes the internal plunger to move, and the locking element returns to the annular groove structure or inclined surface structure of the internal plunger, so that the internal plunger and the driving piston are locked, and the driving piston spring resets the internal plunger and the driving piston. The composite brake mechanism has the advantages of both pure hydraulic brake mechanism and pure mechanical brake mechanism: (a) The valve lift is not affected by the pressure in the cylinder, and the braking power is higher than that of the pure hydraulic brake mechanism. (b) The segmented switching does not affect the structural reliability of the brake mechanism. However, the following problems still need to be improved: (a) It can be seen from the above structure and switching process that it is necessary to ensure that the locking element can move back and forth smoothly between the annular groove of the internal plunger and the groove of the wall of the driving piston assembly, that is, smooth switching requires that when the locking element contacts the annular groove of the internal plunger, the line of action of their combined force is outside the friction angle, otherwise self-locking will occur; similarly, when the locking element contacts the groove of the wall of the driving piston assembly, the line of action of their combined force must also be outside the friction angle, otherwise self-locking will occur. Therefore, the locking element needs to adopt a specially designed shape such as a wedge, roller or sphere, and the annular groove of the internal plunger and the groove of the wall of the driving piston assembly also need to be specially designed; the existing composite brake mechanism only adopts a special design during the switching process. Hydraulic transmission, mechanical transmission is used after the switching is completed, and the impact of gas force will directly act on the braking mechanism; the above-mentioned anti-self-locking design causes the combined force of the locking element and the internal plunger ring groove and the combined force of the locking element and the groove on the wall of the driving piston assembly to be much greater than the force of the valve on the driving piston, and the corresponding contact stress is greatly increased; especially when applied to the braking mechanism on the exhaust side, reliability is difficult to guarantee, and after working for a long time, deformation is prone to occur between the locking element and the groove on the wall of the driving piston assembly, which further causes the actual shape of the locking element and the groove on the wall of the driving piston assembly to gradually deviate from the design shape and become stuck, eventually leading to serious faults such as the engine not being able to work normally.(b) Whether the locking element is in the annular groove of the internal plunger spring or in the groove of the wall of the driving piston assembly, the locking element cannot contact the entire length of the hole on the driving piston because the two ends of the locking element need to adopt special designs that meet smooth switching. The smaller contact surface will further lead to very large contact stress, which is extremely unfavorable to the reliability and life of the locking element and the driving piston. (c) In order to ensure the reliability of the mechanism, the size of the mechanism will be greatly increased, which will make it difficult to meet the engine installation requirements.

[0019] In summary, the inventor proposes to develop a Satisfy at the same time The research goal in the field of engine braking and variable valve mechanism is to have a brake mechanism with unrestricted operating and switching speed ranges, with the highest possible brake power output and good variable valve mechanism reliability, which can provide more brake power output levels and meet the requirements of compact engine installation and the use of original valve mechanism components as much as possible. Summary of the invention

[0020] According to the technical problem raised above, a high-efficiency multi-stage braking mechanism is provided. The technical means adopted by the present invention are as follows:

[0021] A high-efficiency multi-stage braking mechanism comprises a housing, a plunger sleeve arranged on the housing and fixed or reciprocating relative to the housing, a plunger arranged on the plunger sleeve and reciprocating relative to the plunger sleeve, and a hydraulic control unit; when the plunger sleeve is fixed relative to the housing, a second oil chamber is formed between the plunger, the plunger sleeve and the housing or a block fixed relative to the plunger sleeve; when the plunger sleeve reciprocates relative to the housing, a second oil chamber is formed between the plunger and the plunger sleeve; the hydraulic control unit is connected to the second oil chamber through a second oil circuit and a hydraulic linkage valve; when the hydraulic control unit connects the second oil circuit to a high-pressure source, the hydraulic oil enters the second oil chamber through a one-way valve built into the hydraulic linkage valve, but does not exit; the hydraulic control unit connects the second oil circuit to a high-pressure source When the low-pressure source is connected, the hydraulic oil in the second oil chamber enters the second oil circuit through the hydraulic linkage valve or directly enters the low-pressure source; or, the hydraulic control unit is connected to the second oil chamber through two oil circuits, one of which is connected to the second oil chamber through the fourth oil circuit and the one-way valve only in and not out, and the other is connected to the second oil chamber through the fifth oil circuit; there is a limit setting between the plunger sleeve and the plunger to limit the maximum volume of the second oil chamber; at least one first channel is set on the side wall of the plunger sleeve, and a locking body is set in the first channel to reciprocate relative to the first channel; a first oil chamber is formed between the plunger sleeve, the shell and the locking body; the hydraulic control unit is connected to the first oil chamber through the first oil circuit; and a locking body reset mechanism is set on the plunger. In the first effective mode, the first oil circuit is connected to the high-pressure source; the second oil circuit is connected to the high-pressure source, or the fourth oil circuit is connected to the high-pressure source and the fifth oil circuit is cut off. In the failure mode, the first oil circuit is connected to the low-pressure source; the second oil circuit is connected to the low-pressure source, or the fourth oil circuit is cut off or connected to the low-pressure source and the fifth oil circuit is connected to the low-pressure source.

[0022] Further, in the second effective mode, the first oil circuit is connected to the low pressure source; the second oil circuit is connected to the high pressure source, or the fourth oil circuit is connected to the high pressure source and the fifth oil circuit is cut off.

[0023] Furthermore, the locking body reset mechanism has three reset schemes. When the first reset scheme is adopted, at least one second channel is provided on the side wall of the plunger, a spring and a spring seat are provided in the second channel, and a guide mechanism is provided between the plunger and the plunger sleeve; when the volume of the second oil chamber is the largest, the locking body reaches an axial position where the locking body can extend into the second channel or into a circumferential groove provided on the side wall of the plunger and connected to the second channel, and the locking body contacts the spring seat. When the second reset scheme is adopted, at least one circumferential annular groove is provided on the side wall of the plunger, and a spring sheet is provided in the circumferential annular groove; when the volume of the second oil chamber is the largest, the locking body reaches an axial position where the locking body can extend into the circumferential annular groove, and the locking body contacts the spring sheet. When the third reset scheme is adopted, a channel and / or a circumferential groove is set on the side wall of the plunger, a third oil chamber is set between the plunger, the plunger sleeve and the locking body, and the hydraulic control unit is connected to the third oil chamber through the third oil circuit; when the volume of the second oil chamber is maximum, the locking body reaches an axial position where the locking body can extend into the channel or the circumferential groove; when the hydraulic control unit connects the first oil circuit to the high-pressure source, the third oil circuit is connected to the low-pressure source; when the hydraulic control unit connects the first oil circuit to the low-pressure source, the third oil circuit is connected to the high-pressure source.

[0024] Furthermore, the hydraulic linkage valve has three schemes. The first hydraulic linkage valve includes a one-way valve and a two-position three-way linkage valve having a P port, a T port and an A port. The second oil circuit is connected to the P port through the one-way valve, the A port is connected to the second oil chamber, and the T port is connected to the second oil circuit or to the low-pressure source; the second oil circuit is connected to the two-position three-way valve spool drive chamber. When the second oil circuit is connected to the high-pressure source, the P port is connected to the A port, and the T port is cut off; when the second oil circuit is connected to the low-pressure source, the T port is connected to the A port, and the P port is cut off. The second hydraulic linkage valve includes a one-way valve and a two-position two-way linkage valve having a T port and an A port. The second oil circuit is connected to the A port and the second oil chamber at the same time through the one-way valve, and the T port is connected to the second oil circuit or to the low-pressure source; the second oil circuit is connected to the two-position two-way valve spool drive chamber. When the second oil circuit is connected to the high-pressure source, the T port is disconnected from the A port; when the second oil circuit is connected to the low-pressure source, the T port is connected to the A port. The third hydraulic linkage valve includes a one-way valve and a linkage piston rod. The second oil circuit is connected to the second oil chamber through the one-way valve; the second oil circuit is connected to the driving chamber of the linkage piston rod. When the second oil circuit is connected to the high-pressure source, the linkage piston rod does not contact the one-way valve core; when the second oil circuit is connected to the low-pressure source, the linkage piston rod pushes the one-way valve core to be in an open state.

[0025] Furthermore, the hydraulic control unit adopts at least one hydraulic valve, the P port of the hydraulic valve is connected to the high-pressure source, and the T port of the hydraulic valve is connected to the low-pressure source; a variety of schemes can be used to realize the control of the connection relationship between each oil chamber and the high-pressure source and the low-pressure source, thereby realizing the switching of different modes of the mechanism.

[0026] It should be noted that, unless otherwise specified, the reciprocating motions are all reciprocating motions, and relative rotation may or may not occur. If it is necessary to limit the rotational motion of the plunger sleeve relative to the housing, for example, when a roller driven by a cam is provided on the plunger sleeve, a guide mechanism is added between the plunger sleeve and the housing; if it is necessary to limit the relative rotational motion between the plunger and the plunger sleeve, for example, when the locking body adopts a spring plus spring seat reset scheme, a guide mechanism is added between the plunger and the plunger sleeve. A variety of guide schemes can be adopted between the plunger and the plunger sleeve and between the housing and the plunger sleeve. For example, a guide vertical groove is provided on the outer wall of the plunger, and the corresponding end of the locking body or the guide body added to the plunger sleeve always extends into the guide vertical groove; or a guide vertical groove is provided on the inner wall of the plunger sleeve, and the corresponding end of the spring seat or the guide body added to the plunger always extends into the guide vertical groove, so that the guidance between the plunger and the plunger sleeve can be achieved. A guide vertical groove is provided on the inner wall surface of the shell, and the corresponding end of the locking body or the guide body added to the plunger sleeve always extends into the guide vertical groove; or a guide vertical groove is provided on the outer wall surface of the plunger sleeve, and the guide body added to the shell always extends into the guide vertical groove, so that the guidance between the shell and the plunger sleeve can be achieved. A guide vertical groove is provided on the outer wall surface of the plunger and the inner wall surface of the shell, and the two ends of the corresponding locking body or the guide body added to the plunger sleeve always extend into the above-mentioned guide vertical groove, so that the guidance between the shell, the plunger sleeve and the plunger can be achieved. In addition, the above-mentioned guide vertical groove can also be replaced by a guide surface, and the guidance can also be achieved by a pair of guide surfaces or a combination of guide surfaces and guide bodies.

[0027] When the locking body extends into the circumferential groove to achieve locking, in order to reduce contact stress, the side wall surface of the locking body in contact with the circumferential groove can be processed into an arc surface or a plane with a large curvature radius. At this time, an anti-rotation mechanism can be added to the locking body to facilitate locking. For example, a groove is made on the locking body and a retaining ring is installed in the locking body groove to prevent the locking body from rotating. Another example is to set a guide vertical groove on the plunger and / or the outer shell, and the side wall surface perpendicular to the arc surface or plane of the locking body in contact with the circumferential groove is processed into an arc surface or a plane with a large curvature radius that matches the guide vertical groove, and the guide vertical groove is used to prevent the locking body from rotating.

[0028] There are many methods for limiting the maximum volume of the second oil chamber, such as providing a shoulder or a clamping ring on the plunger sleeve, etc. In addition, the limiting function can also be achieved by using a guide body and a guide vertical groove.

[0029] In the scheme in which the plunger sleeve is fixed to the housing, when a shoulder is provided on the plunger sleeve to limit the maximum volume of the second oil chamber, in order to ensure that the hydraulic oil in the second oil chamber does not cause the plunger sleeve to move relative to the housing, it is necessary to limit the plunger sleeve relative to the housing, for example, by installing the plunger sleeve on the housing by means of threads or interference fit, or by limiting the plunger sleeve by means of a retaining ring, or by fixing a block on the plunger sleeve, etc.

[0030] This mechanism proposes a highly efficient multi-stage brake mechanism, which meets various requirements for the design of a variable valve train and has the following advantages:

[0031] (a) This mechanism can replace a certain component of the original valve train, meet the requirements of compact engine installation and use the original valve train components as much as possible, and achieve extremely low-cost product upgrades, which is very conducive to product promotion and application. For example, when the housing and the plunger sleeve move relative to each other, this mechanism can be used as a tappet or valve bridge with multi-stage variable functions, and when the housing and the plunger sleeve are relatively fixed, this mechanism can be used as a rocker arm with multi-stage variable functions or a fixed fulcrum for moving parts such as rocker arms.

[0032] (b) This mechanism not only has the advantages of existing compound brake mechanisms, but also has a more compact size and greatly improved reliability compared to existing compound brake mechanisms. This is because the reciprocating motion of the locking body of this mechanism is achieved by controlling the pressure of the first oil chamber, and there is no problem of self-locking or jamming when adjusting the position of the locking body. The contact parts between the locking body and the housing and the contact parts between the locking body and the plunger do not require special design, and the force on the locking body and the parts in contact with it will not be amplified. Moreover, the locking body can always be in contact with the entire length of the first channel of the plunger sleeve. Both aspects lead to a significant reduction in the contact stress of the mechanism and a significant improvement in the reliability of the mechanism.

[0033] (c) In addition to the first effective mode, the mechanism can also add a second effective mode; when the mechanism is applied to engine braking, the engine has two braking modes, which not only greatly improves the reliability of the braking mechanism, but also increases the number of levels of graded braking. In emergency situations, such as when the main braking system and / or the retarder installed on the vehicle transmission system has or is about to have thermal decay or other failures due to long-term operation, or when the vehicle is heavily loaded on a very steep slope or a very long slope, the engine needs to output the maximum braking power. In this case, all cylinders use the first effective mode; for example, when the engine braking speed exceeds the operating speed range of the second effective mode, in this case, further according to the braking power demand, it is decided that all cylinders or part of the cylinders use the first effective mode. When the first effective mode is used, the valve lift curve of the working cylinder does not change with factors such as the cylinder pressure, and the maximum valve lift is obtained, thereby obtaining the highest engine braking power output. When a larger braking power is required in non-emergency situations, such as when the vehicle is heavily loaded / going down a long slope / steep slope, etc., all cylinders use the second effective mode; when a smaller braking power is required in non-emergency situations, such as when the vehicle is lightly loaded / going down a short slope / gentle slope, etc., some cylinders use the second effective mode. When the second effective mode is used, although the valve lift of the working cylinder changes with factors such as the pressure in the cylinder, and the braking power is reduced, the pressure in the cylinder is significantly reduced, and it has a hydraulic buffering function, so the braking mechanism has high reliability. Compared with various existing braking mechanisms, this mechanism improves the maximum braking power output, increases the number of levels of graded braking, covers a wider range of vehicle braking, increases the proportion of engine braking, reduces the frequency and intensity of use of the main braking system and / or the retarder installed on the vehicle transmission system, increases its service life, and reduces dust pollution in the friction braking system. Compared with a pure mechanical brake mechanism (the effect of a compound brake mechanism is similar to that of a pure mechanical one), the braking power of this mechanism in the first effective mode is improved, and the braking speed range of the three is not limited; this mechanism uses the first effective mode for a short time only in an emergency, which greatly shortens the use time of the first effective mode with greater force of this mechanism while ensuring the maximum braking power output of the engine, and increases the use time of the second effective mode with lower force of the brake mechanism, greatly improving the reliability of this mechanism. Compared with a pure hydraulic brake mechanism, this mechanism has a first effective mode, providing a braking power output with no braking speed range restriction and higher braking power; this mechanism also has a second effective mode, with a significantly lower maximum cylinder pressure and a significantly increased braking speed range, which increases the vehicle speed range of the mechanism in the second effective mode with higher reliability and increases its usage ratio, and the reliability of the brake mechanism of this mechanism is improved. Therefore, this mechanism greatly improves the braking power output and the reliability of the brake mechanism at the same time, and increases the number of braking levels and the usage ratio of engine braking.In addition, this mechanism can also be applied to the engine driving mode to achieve the adjustment of different valve lift curves, thereby realizing engine cylinder deactivation, internal EGR and other technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 It is a schematic diagram of the structure of embodiment 1 of the present mechanism, and is a schematic diagram of a brake mechanism being in a failed state and using a first hydraulic linkage valve.

[0036] Figure 2 a is a structure of an embodiment in which the brake mechanism in embodiment 1 is in the second effective state and the first hydraulic linkage valve is provided; Figure 2 b is a schematic diagram of the guide arrangement between the plunger and the plunger sleeve; Figure 2 c is a schematic diagram of the guide arrangement between the housing and the plunger sleeve; Figure 2 d is that the brake mechanism is in the first effective state and is connected to the second oil chamber by two oil circuits.

[0037] Figure 3 It is a schematic diagram of the structure of the second embodiment of the present mechanism. Figure 3 a is a front view, the brake mechanism is in the first effective state; Figure 3 b is Figure 3 a is the cross-sectional view of the DD section; Figure 3 c is the left view, the brake mechanism is in a failed state, and Figure 3 c shows a schematic diagram of using the second hydraulic linkage valve.

[0038] Figure 4 It is a schematic diagram of using the third hydraulic linkage valve.

[0039] Figure 5 It is a two-position three-way valve. Figure 5 a is its schematic diagram, Figure 5 b and Figure 5 c is a schematic diagram of the structure of an embodiment thereof, Figure 5 b is the first position, Figure 5 c is the second position.

[0040] Figure 6 It is the first two-position four-way valve. Figure 6 a is its schematic diagram, Figure 6 b and Figure 6 c is a schematic diagram of the structure of an embodiment thereof, Figure 6 b is the first position, Figure 6 c is the second position.

[0041] Figure 7 It is the second type of two-position four-way valve. Figure 7 a is its schematic diagram, Figure 7 b and Figure 7 c is a schematic diagram of the structure of an embodiment thereof, Figure 7 b is the first position, Figure 7 c is the second position.

[0042] Figure 8 It is a two-position five-way valve. Figure 8 a is its schematic diagram, Figure 8 b and Figure 8 c is a schematic diagram of the structure of an embodiment thereof, Figure 8 b is the first position, Figure 8 c is the second position.

[0043] Fig. 9 It is a three-position four-way valve. Fig. 9 a is its schematic diagram, Fig. 9 b. Fig. 9 c and Fig. 9 d is a schematic diagram of the structure of an embodiment thereof, Fig. 9 b is the first position, Fig. 9 c is the second position, Fig. 9 d is the third position.

[0044] Fig.10 It is the first three-position five-way valve. Fig.10 a is its schematic diagram, Fig.10 b. Fig.10 c and Fig.10 d is a schematic diagram of the structure of an embodiment thereof, Fig.10 b is the first position, Fig.10 c is the second position, Fig.10 d is the third position.

[0045] Fig.11 It is the second type of three-position five-way valve. Fig.11 a is its schematic diagram, Fig.11 b. Fig.11 c and Fig.11 d is a schematic diagram of the structure of an embodiment thereof, Fig.11 b is the first position, Fig.11 c is the second position, Fig.11 d is the third position.

[0046] Fig.12 It is a three-position six-way valve. Fig.12 a is its schematic diagram, Fig.12 b. Fig.12 c and Fig.12 d is a schematic diagram of the structure of an embodiment thereof, Fig.12 b is the first position, Fig.12 c is the second position, Fig.12 d is the third position.

[0047] Fig.13 The effect of this mechanism when applied to two-stroke braking and its comparison with the prior art, among which, Fig.13 a and Fig.13 b are the comparison diagrams of braking power and maximum cylinder pressure under various braking modes, Fig.13 c is the graded braking effect achieved by this mechanism.

[0048] 1. Shoulder; 2. Housing; 3. Clamp; 4. Plunger sleeve; 5. Plunger; 6. Locking body; 7. First channel; 8. Spring; 9. Spring seat; 10. Second channel; 11. First hydraulic linkage valve; 12. Hydraulic control unit; 13. Check valve; 14. First guide block; 15. Second guide block; 16. Block; 17. Second hydraulic linkage valve; 18. Third hydraulic linkage valve; 19. Linked piston rod; Q1. First oil chamber; Q2. Second oil chamber; Q3. Third oil chamber; A1. First oil circuit; A2. Second oil circuit; A3. Third oil circuit; A4. Fourth oil circuit; A5. Fifth oil circuit; H1. Sliding valve body; H2. Sliding valve check valve; H3. Sliding valve middle port; H4. Sliding valve bushing; H5. Sliding valve check valve spring; H6. Sliding valve block; H7. Sliding valve spring; H8. Sliding valve controlled port; H9. Sliding valve Drive port; H10, slide valve oil drain port; HP, high pressure source; LP, low pressure source; Z1, adopt this mechanism and all cylinders work in the first two-stroke braking mode; Z2, adopt this mechanism and all cylinders work in the second two-stroke braking mode; Z3, adopt pure mechanical mechanism and all cylinders work in the two-stroke braking mode; Z4, adopt pure hydraulic mechanism and all cylinders work in the two-stroke braking mode; Z4, adopt pure mechanical mechanism and all cylinders work in the four-stroke decompression braking mode; Z1L, adopt this mechanism and half of the cylinders work in the first two-stroke braking mode; Z2L, adopt this mechanism and half of the cylinders work in the second two-stroke braking mode; SZ2, the operating speed range of this mechanism in the second two-stroke braking mode; SZ4, the operating speed range of the pure hydraulic mechanism in the two-stroke braking mode. In the figure, the valve ports of each hydraulic valve are distinguished by a single capital letter, among which the P port is always connected to the high pressure source, and the T port is always connected to the low pressure source. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] This embodiment discloses a high-efficiency multi-stage brake mechanism, including a housing 2, a plunger sleeve 4 disposed on the housing 2 and fixed or reciprocating relative to the housing 2, a plunger 5 disposed on the plunger sleeve 4 and reciprocating relative to the plunger sleeve 4, and a hydraulic control unit 12. When the plunger sleeve 4 is fixed relative to the housing 2, a second oil chamber Q2 is formed between the plunger 5, the plunger sleeve 4 and the housing 2 or a block 16 fixed relative to the plunger sleeve 4. When the plunger sleeve 4 reciprocates relative to the housing 2, a second oil chamber Q2 is formed between the plunger 5 and the plunger sleeve 4. The hydraulic control unit 12 is connected to the second oil chamber Q2 in a variety of ways. The hydraulic control unit 12 is connected to the second oil chamber Q2 through the second oil circuit A2 and the hydraulic linkage valve. When the hydraulic control unit 12 connects the second oil circuit A2 to the high pressure source HP, the hydraulic oil enters the second oil chamber Q2 through the one-way valve built into the hydraulic linkage valve. When the hydraulic control unit 12 connects the second oil circuit A2 to the low pressure source LP, the hydraulic oil in the second oil chamber Q2 enters the second oil circuit A2 or directly enters the low pressure source LP through the hydraulic linkage valve. Alternatively, the hydraulic control unit 12 is connected to the second oil chamber Q2 through two oil circuits, one of which is connected to the second oil chamber Q2 through the fourth oil circuit A4 and the one-way valve 13, and the other is connected to the second oil chamber Q2 through the fifth oil circuit A5. There is a limit setting between the plunger sleeve 4 and the plunger 5 to limit the maximum volume of the second oil chamber Q2. At least one first channel 7 is set on the side wall of the plunger sleeve 4, and a locking body 6 is set in the first channel 7 to reciprocate relative to the first channel 7. The first oil chamber Q1 is formed between the plunger sleeve 4, the housing 2 and the locking body 6. The hydraulic control unit 12 is connected to the first oil chamber Q1 through the first oil passage A1. The plunger 5 is provided with a locking body resetting mechanism.

[0051] Example 1

[0052] Figure 1 It is a schematic diagram of the structure of the embodiment 1 of this mechanism. Figure 1It can be seen that the mechanism includes a housing 2, a plunger sleeve 4 disposed on the housing 2 and reciprocating relative to the housing 2, a plunger 5 disposed on the plunger sleeve 4 and reciprocating relative to the plunger sleeve 4, and a hydraulic control unit 12. A second oil chamber Q2 is formed between the plunger 5 and the plunger sleeve 4. A clamping ring is disposed on the plunger sleeve 4 as a limit setting for limiting the maximum volume of the second oil chamber Q2. Two first channels 7 are disposed on the side wall of the plunger sleeve 4, and a locking body 6 is disposed in each first channel 7 and reciprocating relative to the first channel 7. A first oil chamber Q1 is formed between the plunger sleeve 4, the housing 2 and the locking body 6. The hydraulic control unit 12 is connected to the first oil chamber Q1 through the first oil circuit A1. When the locking body 6 adopts the first reset scheme, a second channel 10 is disposed on the side wall of the plunger 5, and a spring 8 and two spring seats 9 are disposed in the second channel 10. When the volume of the second oil chamber Q2 is the largest, the locking body 6 reaches an axial position where the locking body 6 can extend into the second channel 10, and the two locking bodies 6 are in contact with the two spring seats 9 respectively. The hydraulic control unit 12 is connected to the second oil chamber Q2 in a variety of ways.

[0053] When the locking body is reset by using a spring and a spring seat, a guide mechanism is provided between the plunger 5 and the plunger sleeve 4. The guide mechanism can adopt a variety of schemes, for example, Figure 1 In the embodiment, a guide vertical groove is provided on the plunger 5 and the plunger sleeve 4, and a first guide block 14 is used to guide the two. Figure 2 As shown in b. Figure 3 , a guide vertical groove is provided on the plunger 5, and a second guide block 15 provided on the plunger sleeve 4 is used to guide the two. For example, in the case where a roller driven by a cam is provided on the plunger sleeve, a guide mechanism needs to be provided between the plunger sleeve 4 and the housing 2. The guide can adopt a variety of schemes, for example, Figure 1 In the embodiment, a guide vertical groove is provided on the inner wall surface of the housing 2, and the whole or part of the locking body 6 provided on the plunger sleeve 4 is used to guide the two. Figure 2 As shown in c.

[0054] In order to increase the reliability of the mechanism, the number of first channels 7 may be further increased at different circumferential and / or axial positions on the side wall of the plunger sleeve 4, thereby increasing the number of locking bodies 6 to reduce the force on each locking body 6, for example Figure 1 Two locking bodies 6 are used. Figure 3Three locking bodies 6 are used. In order to reduce the contact stress, a circumferential groove can also be set on the outer wall surface of the plunger 5. When the spring and spring seat are used to realize the reset of the locking body 6, the circumferential groove needs to be connected to the second channel 10. When the plunger 5 and the plunger sleeve 4 are locked by the locking body 6, the locking body 6 extends into the circumferential groove. Compared with the second channel 10, the curvature radius of the circumferential groove is larger. Under the same force, the contact stress between the locking body 6 and the circumferential groove is reduced. In order to further reduce the contact stress, the side wall surface of the locking body 6 in contact with the circumferential groove can be processed into an arc surface or a plane with a large curvature radius, such as Figure 3 a is visible. At this time, an anti-rotation mechanism can be added to the locking body 6 to facilitate locking. For example, a groove is made on the locking body 6 and the clamp ring is installed in the groove of the locking body 6. For example, a guide vertical groove is provided on the plunger 5 and / or the housing 2, and a side wall surface perpendicular to the arc surface or plane of the locking body 6 for contacting the circumferential groove is processed into an arc surface or plane with a large curvature radius that matches the guide vertical groove, and the arc surface or plane is used together with the guide vertical groove to prevent the locking body 6 from rotating.

[0055] Figure 1 A scheme of using a first hydraulic linkage valve 11 is provided, including a one-way valve and a two-position three-way linkage valve having a P port, a T port and an A port. The one-way valve and the two-position three-way valve can be separate structures or integrated structures. The hydraulic control unit 12 is connected to the P port through the second oil circuit A2 and the one-way valve, the A port is connected to the second oil chamber Q2, and the T port is connected to the second oil circuit A2 or to the low-pressure source LP. The second oil circuit A2 is connected to the valve core driving chamber of the two-position three-way valve. When the hydraulic control unit 12 connects the second oil circuit A2 to the high-pressure source HP, the two-position three-way valve core is driven by the hydraulic oil so that the P port is connected to the A port, and the T port is cut off. The hydraulic oil of the high-pressure source HP passes through the one-way valve and the P port and the A port of the two-position three-way valve and enters the second oil chamber Q2 without exiting. The plunger 5 continuously moves upward relative to the plunger sleeve 4, and the volume of the second oil chamber Q2 continuously increases until the plunger 5 is limited by the clamping ring set on the plunger sleeve 4, and the plunger 5 reaches the maximum lift relative to the plunger sleeve 4, that is, reaches Figure 3 b state. On this basis, when the hydraulic control unit 12 connects the first oil circuit A1 to the low-pressure source LP, under the action of the spring force, the locking body 6 is still on the side of the housing 2 and the plunger sleeve 4, and the plunger 5 and the plunger sleeve 4 are not locked, and the second effective mode is realized. Due to the effects of the pressure in the engine cylinder, the movement of the plunger 5 and the movement of the plunger sleeve 4 cannot be completely consistent, especially in the engine braking mode, when the exhaust valve moves at the top dead center, the movement difference between the two is very large, which causes the exhaust valve lift curve to change with the change of the pressure in the engine cylinder, etc. When the hydraulic control unit 12 connects the first oil circuit A1 to the high-pressure source HP, the liquid pressure on the locking body 6 overcomes the spring force, and the locking body 6 moves to the side of the plunger sleeve 4 and the plunger 5, and the plunger 5 and the plunger sleeve 4 are locked into one by the locking body 6, as shown in FIG. Figure 2d, the first effective mode is realized. In addition, the effects of the engine cylinder pressure and other effects have very little effect on the movement of the plunger 5. The movement of the plunger 5 and the movement of the plunger sleeve 4 are highly consistent, and the valve lift curve remains unchanged. It should be noted that whether the second effective mode exists for a long time is determined by the hydraulic valve structure and type used by the hydraulic control unit 12, which will be explained in detail later. In the case where the second effective mode does not exist, Figure 2 The state a is a transition state between the failure mode and the first effective mode. When the hydraulic control unit 12 connects the first oil circuit A1 to the low pressure source LP and the second oil circuit A2 to the low pressure source LP, the valve core of the two-position three-way valve is reset and the T port is connected to the A port, and the P port is cut off. Under the action of the spring force, the locking body 6 returns to the side of the housing 2 and the plunger sleeve 4, and the hydraulic oil in the second oil chamber Q2 passes through the A port and the T port, and then passes through the second oil circuit A2 or directly returns to the low pressure source LP, and the plunger 5 continues to move downward relative to the plunger sleeve 4 until it returns to the Figure 1 State, the failure mode is realized. At this time, the plunger sleeve 4 drives the plunger 5 to move, but the plunger 5 will not be able to drive or completely drive the subsequent parts of the valve mechanism to move, and the valve lift will always be zero or the small lift part of the cam will not be reflected on the valve lift curve. When the stroke of the plunger 5 relative to the plunger sleeve 4 is greater than the stroke of the plunger sleeve 4 corresponding to the maximum protrusion of the cam, in the failure mode, the valve lift can be always zero, for example, when this mechanism is used in the two-stroke mode or the engine cylinder stop mode. When the stroke of the plunger 5 relative to the plunger sleeve 4 is less than the stroke of the plunger sleeve 4 corresponding to the maximum protrusion of the cam, in the failure mode, the valve lift will not be able to be always zero, for example, when this mechanism is used in the four-stroke decompression braking or four-stroke deflation braking modes, or when the engine driving mode requires a smaller valve lift or realizes internal EGR.

[0056] Figure 2a shows an embodiment structure of the first hydraulic linkage valve 11, that is, a structure in which a one-way valve and a two-position four-way valve are integrated into one body. The slide valve one-way valve H2 is arranged in the slide valve body H1, and the slide valve block H6 is on the slide valve body H1. When the hydraulic control unit 12 connects the second oil circuit A2 with the high-pressure source HP, the high-pressure oil enters the slide valve controlled port H8 to push the slide valve body H1 downward, connects the slide valve middle port H3 with the slide valve drive port H9, and the slide valve oil drain port H10 is cut off. After overcoming the slide valve one-way valve spring H5, the high-pressure oil enters the second oil chamber Q2 through the one-way valve, the slide valve middle port H3, and the slide valve drive port H9, pushing the plunger 5 upward relative to the plunger sleeve 4. When the hydraulic control unit 12 connects the second oil circuit A2 to the low-pressure source LP, the slide valve spring H7 pushes the slide valve body H1 upward to reset, the slide valve middle port H3 is cut off, the slide valve drive port H9 is connected to the slide valve oil drain port H10, and the high-pressure oil in the second oil chamber Q2 returns to the low-pressure source LP through the slide valve drive port H9 and the slide valve oil drain port H10, and the plunger 5 is reset downward relative to the plunger sleeve 4. The provision of the slide valve bushing H4 can realize modular design, which is convenient for slide valve installation and replacement.

[0057] Figure 2 d shows the situation where the hydraulic control unit 12 is connected to the second oil chamber Q2 through two oil circuits. One circuit is connected to the second oil chamber Q2 through the fourth oil circuit A4 and the one-way valve 13, and the other circuit is connected to the second oil chamber Q2 through the fifth oil circuit A5. When the hydraulic control unit 12 connects the fourth oil circuit A4 to the high-pressure source HP and the fifth oil circuit A5 is cut off, the high-pressure oil flows into the second oil chamber Q2 through the fourth oil circuit A4 and the one-way valve 13, and pushes the plunger 5 upward relative to the plunger sleeve 4. When the hydraulic control unit 12 cuts off the fourth oil circuit A4 or connects it to the low-pressure source LP and the fifth oil circuit A5 is connected to the low-pressure source LP, the hydraulic oil in the second oil chamber Q2 returns to the low-pressure source LP through the fifth oil circuit A5, and the plunger 5 is reset downward relative to the plunger sleeve 4. With this solution, the control of the second oil chamber Q2 can be achieved without setting a hydraulic linkage valve, and the structure of the braking mechanism is simplified.

[0058] Example 2

[0059] Figure 3 This is a schematic diagram of the structure of the second embodiment of the present mechanism. Figure 3 It can be seen that the mechanism includes a housing 2, a plunger sleeve 4 fixed on the housing 2, a plunger 5 arranged on the plunger sleeve 4 and reciprocating relative to the plunger sleeve 4, and a hydraulic control unit 12. A second oil chamber Q2 is formed between the plunger 5 and the plunger sleeve 4. A shoulder is provided on the plunger sleeve 4 to limit the maximum volume of the second oil chamber Q2. Three circumferentially uniformly distributed first channels 7 are provided on the side wall of the plunger sleeve 4, and a locking body 6 is provided in each first channel 7 to reciprocate relative to the first channel 7.

[0060] Figure 3The third reset scheme is adopted. A circumferential groove is provided on the side wall of the plunger 5. A third oil chamber Q3 is provided between the plunger 5, the plunger sleeve 4 and the locking body 6. The hydraulic control unit 12 is connected to the third oil chamber Q3 through the third oil circuit A3. When the volume of the second oil chamber Q2 is the largest, the locking body 6 reaches an axial position where the locking body 6 can extend into the circumferential groove. When the hydraulic control unit 12 connects the first oil circuit A1 with the high-pressure source HP, the third oil circuit A3 is connected to the low-pressure source LP, and the locking body 6 is pushed into the circumferential groove of the plunger 5 by the hydraulic oil, locking the plunger 5 and the plunger sleeve 4 into one. When the hydraulic control unit 12 connects the first oil circuit A1 with the low-pressure source LP, the third oil circuit A3 is connected to the high-pressure source HP, and the locking body 6 is pushed out of the circumferential groove of the plunger 5 by the hydraulic oil, and the plunger 5 and the plunger sleeve 4 are not locked. When the third reset scheme is adopted, a channel is also provided on the plunger sleeve 4, which connects the third oil circuit A3 and the third oil chamber Q3.

[0061] In addition, the locking body can also adopt a second reset scheme, in which at least one circumferential groove is provided on the side wall of the plunger 5, and a spring sheet is provided in the circumferential groove. When the volume of the second oil chamber Q2 is the largest, the locking body 6 reaches an axial position where the locking body 6 can extend into the circumferential groove, and the locking body 6 contacts the spring sheet. The spring force of the spring sheet is used to achieve the reset of the locking body 6.

[0062] Figure 3 c shows a schematic diagram of the second hydraulic linkage valve. The second hydraulic linkage valve 17 includes a one-way valve and a two-position two-way linkage valve with a T port and an A port. The second oil circuit A2 is connected to the A port and the second oil chamber Q2 at the same time through the one-way valve, and the T port is connected to the second oil circuit A2 or connected to the low-pressure source LP. The second oil circuit A2 is connected to the two-position two-way valve spool drive chamber. When the hydraulic control unit 12 connects the second oil circuit A2 to the high-pressure source HP, the high-pressure oil drives the two-position two-way valve spool to disconnect its T port from the A port, and the high-pressure oil enters the second oil chamber Q2 through the one-way valve, pushing the plunger 5 upward relative to the plunger sleeve 4. When the hydraulic control unit 12 connects the second oil circuit A2 to the low-pressure source LP, the two-position two-way valve spool is reset and its T port is connected to the A port. The hydraulic oil in the second oil chamber Q2 passes through the A port and the T port, and then passes through the second oil circuit A2 or directly enters the low-pressure source LP, and the plunger 5 is reset relative to the plunger sleeve 4 downward.

[0063] Figure 4It is a schematic diagram of the use of the third hydraulic linkage valve. It includes a one-way valve and a linkage piston rod 19. The second oil circuit A2 is connected to the second oil chamber Q2 through the one-way valve. The second oil circuit A2 is connected to the drive chamber of the linkage piston rod 19. When the hydraulic control unit 12 connects the second oil circuit A2 to the high-pressure source HP, the linkage piston rod 19 moves a certain distance under the action of the high-pressure oil, so that the linkage piston rod 19 does not contact the one-way valve core, and the high-pressure oil flows into the second oil chamber Q2 through the one-way valve, pushing the plunger 5 upward relative to the plunger sleeve 4. When the hydraulic control unit 12 connects the second oil circuit A2 to the low-pressure source LP, the linkage piston rod 19 resets and pushes the one-way valve core to be in the open state, and the hydraulic oil in the second oil chamber Q2 returns to the low-pressure source LP through the one-way valve that is always open, and the plunger 5 resets downward relative to the plunger sleeve 4.

[0064] The hydraulic control unit 12 uses at least one hydraulic valve, a P port of the hydraulic valve is connected to the high pressure source HP, and a T port of the hydraulic valve is connected to the high pressure source HP. Figures 5 to 12 The embodiment of the hydraulic valve used in the hydraulic control unit of the mechanism is given. The type and connection mode of the hydraulic valve are different, and the engine operation mode realized is also different. The following are some embodiments of the type of hydraulic valve used in the mechanism and the engine operation mode that can be realized.

[0065] The first solution: a two-position three-way valve is used, whose port A is connected to the first oil circuit A1 and the second oil circuit A2. When the valve core is in the first position, port A is connected to port T and port P is blocked. When the valve core is in the second position, port A is connected to port P and port T is blocked. Figure 5 a is a schematic diagram of a two-position three-way valve corresponding to the first solution, Figure 5 b and Figure 5 c is a schematic diagram of the structure of an embodiment thereof, Figure 5 b is the first position, Figure 5 c is the second position.

[0066] The second solution: a two-position four-way valve is used, with port A connected to the first oil circuit A1 and the second oil circuit A2, and port B connected to the third oil circuit A3. When the valve core is in the first position, port A is connected to port T, and port B is connected to port P. When the valve core is in the second position, port A is connected to port P, and port B is connected to port T. Figure 6 a is a schematic diagram of a two-position four-way valve corresponding to the second solution. Figure 6 b and Figure 6 c is a schematic diagram of the structure of an embodiment thereof, Figure 6 b is the first position, Figure 6 c is the second position.

[0067] The third solution: a two-position four-way valve is used, with port A connected to the first oil circuit A1 and the fourth oil circuit A4, and port B connected to the fifth oil circuit A5. When the valve core is in the first position, ports A and B are both connected to port T, and port P is blocked. When the valve core is in the second position, port A is connected to port P, and ports B and T are both blocked. Figure 7 a is a schematic diagram of a two-position four-way valve corresponding to the third solution. Figure 7 b and Figure 7 c is a schematic diagram of the structure of an embodiment thereof, Figure 7 b is the first position, Figure 7 c is the second position.

[0068] The fourth solution: a two-position five-way valve is used, wherein port A is connected to the first oil circuit A1 and the fourth oil circuit A4, port B is connected to the fifth oil circuit A5, and port C is connected to the third oil circuit A3. When the valve core is in the first position, ports A and B are both connected to port T, and port C is connected to port P. When the valve core is in the second position, port A is connected to port P, port B is blocked, and port C is connected to port T. Figure 8 a is a schematic diagram of a two-position five-way valve corresponding to the fourth scheme. Figure 8 b and Figure 8 c is a schematic diagram of the structure of an embodiment thereof, Figure 8 b is the first position, Figure 8 c is the second position.

[0069] When any one of the first to fourth solutions is adopted, when the engine needs to operate in the failure mode, the valve core is switched to the first position. When the engine needs to operate in the first effective mode, the valve core is switched to the second position.

[0070] The fifth scheme: a three-position four-way valve is used, whose port A is connected to the first oil circuit A1, and port B is connected to the second oil circuit A2. When the valve core is in the first position, ports A and B are both connected to port T, and port P is blocked. When the valve core is in the second position, port B is connected to port P, and port A is connected to port T. When the valve core is in the third position, ports A and B are both connected to port P, and port T is blocked. Fig. 9 a is a schematic diagram of a three-position four-way valve corresponding to the fifth scheme. Fig. 9 b. Fig. 9 c and Fig. 9 d is a schematic diagram of the structure of an embodiment thereof, Fig. 9 b is the first position, Fig. 9 c is the second position, Fig. 9 d is the third position.

[0071] The sixth scheme: a three-position five-way valve is used, whose port A is connected to the first oil circuit A1, port B is connected to the fourth oil circuit A4, and port C is connected to the fifth oil circuit A5. When the valve core is in the first position, ports A and C are both connected to port T, port P is blocked, and port B is connected to port T or port B is blocked. When the valve core is in the second position, port B is connected to port P, port C is blocked, and port A is connected to port T. When the valve core is in the third position, ports A and B are both connected to port P, and ports C and T are both blocked. Fig.10 a is a schematic diagram of a three-position five-way valve corresponding to the sixth scheme. Fig.10 b. Fig.10 c and Fig.10 d is a schematic diagram of the structure of an embodiment thereof, Fig.10 b is the first position, Fig.10 c is the second position, Fig.10 d is the third position.

[0072] The seventh scheme: a three-position five-way valve is used, whose port A is connected to the first oil circuit A1, port B is connected to the second oil circuit A2, and port C is connected to the third oil circuit A3. When the valve core is in the first position, ports A and B are connected to port T, and port C is connected to port P. When the valve core is in the second position, ports B and C are connected to port P, and port A is connected to port T. When the valve core is in the third position, ports A and B are connected to port P, and port C is connected to port T. Fig.11 a is the schematic diagram of the three-position five-way valve corresponding to the seventh scheme, Fig.11 b. Fig.11 c and Fig.11 d is a schematic diagram of the structure of an embodiment thereof, Fig.11 b is the first position, Fig.11 c is the second position, Fig.11 d is the third position.

[0073] The eighth solution: a three-position six-way valve is used, whose port A is connected to the first oil circuit A1, port B is connected to the fourth oil circuit A4, port C is connected to the fifth oil circuit A5, and port D is connected to the third oil circuit A3. When the valve core is in the first position, ports A and C are both connected to port T, port B is cut off or connected to port T, and port D is connected to port P. When the valve core is in the second position, ports B and D are both connected to port P, port C is cut off, and port A is connected to port T. When the valve core is in the third position, ports A and B are both connected to port P, port C is cut off, and port D is connected to port T. Fig.12 a is the schematic diagram of the three-position six-way valve corresponding to the eighth scheme, Fig.12 b. Fig.12 c and Fig.12 d is a schematic diagram of the structure of an embodiment thereof, Fig.12 b is the first position, Fig.12 c is the second position, Fig.12 d is the third position.

[0074] When any of the fifth to eighth solutions is adopted, when the engine needs to operate in the failure mode, the valve core is switched to the first position. When the engine needs to operate in the second effective mode, the valve core is switched to the second position. When the engine needs to operate in the first effective mode, the valve core is switched to the third position.

[0075] Ninth solution: Two two-position three-way valves are used. The A port of the first two-position three-way valve is connected to the first oil circuit A1. When the valve core is in the first position, the A port is connected to the T port, and the P port is blocked. When the valve core is in the second position, the A port is connected to the P port, and the T port is blocked. The A port of the second two-position three-way valve is connected to the second oil circuit A2. When the valve core is in the first position, the A port is connected to the T port, and the P port is blocked. When the valve core is in the second position, the A port is connected to the P port, and the T port is blocked. When the engine needs to run in the failure mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to the first position. When the engine needs to run in the second effective mode, the first two-position three-way valve is switched to the first position, and the valve cores of the second two-position three-way valve are switched to the second position. When the engine needs to run in the first effective mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to the second position. The two-position three-way valve used in the ninth solution is as follows: Figure 5 shown.

[0076] The tenth scheme: a two-position three-way valve and a two-position four-way valve are used. The A port of the two-position three-way valve is connected to the second oil circuit A2. When the valve core is in the first position, the A port is connected to the T port, and the P port is blocked. When the valve core is in the second position, the A port is connected to the P port, and the T port is blocked. The A port of the two-position four-way valve is connected to the first oil circuit A1, and the B port of the two-position four-way valve is connected to the third oil circuit A3. When the valve core is in the first position, the A port is connected to the T port, and the B port is connected to the P port. When the valve core is in the second position, the A port is connected to the P port, and the B port is connected to the T port. When the engine needs to run in the failure mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the first position. When the engine needs to run in the second effective mode, the two-position three-way valve is switched to the second position, and the valve core of the two-position four-way valve is switched to the first position. When the engine needs to run in the first effective mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the second position. The two-position three-way valve used in the tenth scheme is as follows: Figure 5 As shown, the two-position four-way valve used is as follows Figure 6 shown.

[0077] The eleventh scheme: a two-position three-way valve and a two-position four-way valve are used. The A port of the two-position three-way valve is connected to the first oil circuit A1. When the valve core is in the first position, the A port is connected to the T port, and the P port is blocked. When the valve core is in the second position, the A port is connected to the P port, and the T port is blocked. The A port of the two-position four-way valve is connected to the fourth oil circuit A4, and the B port is connected to the fifth oil circuit A5. When the valve core is in the first position, the A port is blocked or connected to the T port, and the B port is connected to the T port, and the P port is blocked. When the valve core is in the second position, the A port is connected to the P port, and both the B port and the T port are blocked. When the engine needs to run in the failure mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the first position. When the engine needs to run in the second effective mode, the two-position three-way valve is switched to the first position, and the valve core of the two-position four-way valve is switched to the second position. When the engine needs to run in the first effective mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the second position. The two-position three-way valve used in the eleventh scheme is as follows: Figure 5 As shown, the two-position four-way valve used is as follows Figure 7 shown.

[0078] The twelfth scheme: two two-position four-way valves are used. The first two-position four-way valve is used. The port A is connected to the first oil circuit A1, and the port B is connected to the third oil circuit A3. When the valve core is in the first position, the port A is connected to the port T, and the port B is connected to the port P. When the valve core is in the second position, the port A is connected to the port P, and the port B is connected to the port T. The second two-position four-way valve is used. The port A is connected to the fourth oil circuit A4, and the port B is connected to the fifth oil circuit A5. When the valve core is in the first position, the port A is blocked or connected to the port T, the port B is connected to the port T, and the port P is blocked. When the valve core is in the second position, the port A is connected to the port P, and the ports B and T are both blocked. When the engine needs to run in the failure mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to the first position. When the engine needs to run in the second effective mode, the first two-position four-way valve is switched to the first position, and the valve core of the second two-position four-way valve is switched to the second position. When the engine needs to run in the first effective mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to the second position. The first two-position four-way valve used in the twelfth scheme is as follows Figure 6 As shown, the second two-position four-way valve used is as follows Figure 7 shown.

[0079] This mechanism can be used to realize a two-stroke braking mode, a four-stroke decompression braking mode, a four-stroke deflation braking mode, a cylinder deactivation mode, different four-stroke drive modes, internal EGR, etc. Fig.13 This is a comparison between the effect of this mechanism when applied to two-stroke braking of a certain vehicle and the existing braking mechanism, among which: Fig.13 a and Fig.13 b are the comparison diagrams of the braking power and maximum cylinder pressure of various braking mechanisms when all cylinders are in braking mode, Fig.13c is the graded braking effect achieved by this mechanism. This mechanism achieves the first two-stroke braking mode in the first effective mode and the second two-stroke braking mode in the second effective mode. The effect of the compound braking mechanism is similar to that of the pure mechanical braking mechanism. Compared with the pure mechanical braking mechanism, the braking power of this mechanism in the first effective mode is increased by 0.5-9.5%, and the braking speed range of the three is not restricted; the compound braking mechanism and the pure mechanical braking mechanism both use mechanical locking during the entire engine braking process, and the force on the relevant components is always very high, while this mechanism only uses the first effective mode for a short time in an emergency. This ensures the maximum braking power output of the engine while greatly shortening the use time of the first effective mode of the mechanism with high force, and increasing the use time of the second effective mode of the brake mechanism with low force. The maximum cylinder pressure of this mechanism in the second effective mode is reduced by 21.1-36.8%, greatly improving the reliability of this mechanism. Compared with the pure hydraulic brake mechanism, the first two-stroke brake mode of this mechanism can provide no brake speed range limit, and the brake power is increased by 14.1-38.7%; the second effective mode of this mechanism is to provide more brake levels of graded braking, and the brake power output under each brake level needs to be significantly different to cover a wider range of vehicle braking operating conditions. Therefore, it is necessary to reduce its brake power. Compared with the pure hydraulic brake mechanism, the maximum cylinder pressure is reduced by 11.2-13.8%, and the brake speed range is expanded by 165%, which greatly broadens the vehicle speed range of the mechanism in the second effective mode with higher reliability, and greatly increases the use ratio of the mechanism in the second effective mode, and the reliability of the brake mechanism of this mechanism is improved. Therefore, this mechanism greatly improves the brake power output and the reliability of the brake mechanism at the same time, and increases the number of brake levels and the use ratio of engine braking. Compared with the pure mechanical brake mechanism which is the most widely used and has the highest braking power output in the market and is applied to the four-stroke decompression braking mode, the braking power of this mechanism in the first effective mode and the second effective mode are significantly higher than that of the four-stroke decompression braking mode of the pure mechanical mechanism, which are increased by 118-166.1% and 78.9-89.8% respectively; the maximum cylinder pressure of this mechanism in the first effective mode is higher than that of the four-stroke decompression braking mode of the pure mechanical mechanism, but with the increase of the speed, the difference between the two becomes smaller and smaller, and the maximum cylinder pressure of this mechanism in the second effective mode is reduced by 6-47.8% compared with the four-stroke decompression braking mode of the pure mechanical mechanism; since the first and second stroke braking modes of this mechanism are only used in emergency situations, and the second and second stroke braking modes are used in conventional non-emergency situations, therefore, this mechanism can not only obtain the braking power required to meet the vehicle's greater braking operating conditions, but also obtain better reliability of the valve mechanism. Fig.13c shows four different levels of braking power output achieved when the mechanism is applied to the two-stroke braking mode by adopting the first effective mode and the second effective mode in half of the cylinders and all of the cylinders respectively. Similarly, other braking power outputs can be obtained by further changing the number of cylinders operating in the braking mode. Compared with the existing braking mechanism, the number of braking levels of this mechanism has doubled. When this mechanism is applied to four-stroke decompression braking, four-stroke deflation braking and other modes, it can also achieve a variety of different levels of braking power output. Its advantages over other braking mechanisms are similar and will not be repeated in this article.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency multi-stage braking mechanism, characterized in that: It comprises a housing (2), a plunger sleeve (4) arranged on the housing (2) and fixed or reciprocating relative to the housing (2), a plunger (5) arranged on the plunger sleeve (4) and reciprocating relative to the plunger sleeve (4), and a hydraulic control unit (12); When the plunger sleeve (4) is fixed relative to the housing (2), a second oil chamber (Q2) is formed between the plunger (5), the plunger sleeve (4) and the housing (2) or a block (16) fixed relative to the plunger sleeve (4); when the plunger sleeve (4) reciprocates relative to the housing (2), a second oil chamber (Q2) is formed between the plunger (5) and the plunger sleeve (4); The hydraulic control unit (12) is connected to the second oil chamber (Q2) through the second oil circuit (A2) and the hydraulic linkage valve. When the hydraulic control unit (12) connects the second oil circuit (A2) to the high pressure source (HP), the hydraulic oil enters the second oil chamber (Q2) through the one-way valve built into the hydraulic linkage valve, but does not enter. When the hydraulic control unit (12) connects the second oil circuit (A2) to the low pressure source (LP), the hydraulic oil in the second oil chamber (Q2) enters the second oil circuit (A2) or directly enters the low pressure source (LP) through the hydraulic linkage valve; or, the hydraulic control unit (12) is connected to the second oil chamber (Q2) through two oil circuits, one of which is connected to the second oil chamber (Q2) through the fourth oil circuit (A4) and the one-way valve (13), but does not enter, and the other is connected to the second oil chamber (Q2) through the fifth oil circuit (A5); A limit device for limiting the maximum volume of the second oil chamber (Q2) is provided between the plunger sleeve (4) and the plunger (5); at least one first channel (7) is provided on the side wall of the plunger sleeve (4), and a locking body (6) is provided in the first channel (7) and reciprocates relative to the first channel (7); a first oil chamber (Q1) is formed between the plunger sleeve (4), the housing (2) and the locking body (6); the hydraulic control unit (12) is connected to the first oil chamber (Q1) via a first oil circuit (A1); and a locking body reset mechanism is provided on the plunger (5); In the first effective mode, the first oil circuit (A1) is connected to the high pressure source (HP); The second oil circuit (A2) is connected to the high pressure source (HP), or the fourth oil circuit (A4) is connected to the high pressure source (HP) and the fifth oil circuit (A5) is blocked; In the failure mode, the first oil circuit (A1) is connected to the low pressure source (LP); The second oil path (A2) is connected to the low pressure source (LP), or the fourth oil path (A4) is blocked or connected to the low pressure source (LP) and the fifth oil path (A5) is connected to the low pressure source (LP).

2. The high-efficiency multi-stage braking mechanism according to claim 1, characterized in that: In the second effective mode, the first oil circuit (A1) is connected to the low pressure source (LP); The second oil passage (A2) is connected to the high pressure source (HP), or the fourth oil passage (A4) is connected to the high pressure source (HP) and the fifth oil passage (A5) is blocked.

3. The high-efficiency multi-stage braking mechanism according to claim 1, characterized in that: The locking body reset mechanism has three reset schemes; When the first reset scheme is adopted, at least one second channel (10) is arranged on the side wall of the plunger (5), a spring (8) and a spring seat (9) are arranged in the second channel (10), and a guide mechanism is arranged between the plunger (5) and the plunger sleeve (4); when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position where the locking body (6) can extend into the second channel (10) or into a circumferential groove arranged on the side wall of the plunger (5) and connected to the second channel (10), and the locking body (6) contacts the spring seat (9); When the second reset scheme is adopted, at least one circumferential annular groove is provided on the side wall of the plunger (5), and a spring sheet is provided in the circumferential annular groove; when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position where the locking body (6) can extend into the circumferential annular groove, and the locking body (6) contacts the spring sheet; When the third reset scheme is adopted, a channel and / or a circumferential groove is provided on the side wall of the plunger (5), a third oil chamber (Q3) is provided between the plunger (5), the plunger sleeve (4) and the locking body (6), and the hydraulic control unit (12) is connected to the third oil chamber (Q3) via a third oil circuit (A3); when the volume of the second oil chamber (Q2) is maximum, the locking body (6) reaches an axial position where the locking body (6) can extend into the channel or the circumferential groove; when the hydraulic control unit (12) connects the first oil circuit (A1) to a high pressure source (HP), the third oil circuit (A3) is connected to a low pressure source (LP); when the hydraulic control unit (12) connects the first oil circuit (A1) to a low pressure source (LP), the third oil circuit (A3) is connected to a high pressure source (HP).

4. The high-efficiency multi-stage braking mechanism according to claim 1, characterized in that: There are three schemes for the hydraulic linkage valve: When the first hydraulic linkage valve scheme is adopted, the first hydraulic linkage valve (11) comprises a one-way valve and a two-position three-way linkage valve having a P port, a T port and an A port, the second oil circuit (A2) is connected to the P port through the one-way valve, the A port is connected to the second oil chamber (Q2), and the T port is connected to the second oil circuit (A2) or to a low-pressure source (LP); the second oil circuit (A2) is connected to the two-position three-way valve core drive chamber, when the second oil circuit (A2) is connected to the high-pressure source (HP), the P port is connected to the A port, and the T port is blocked; when the second oil circuit (A2) is connected to the low-pressure source (LP), the T port is connected to the A port, and the P port is blocked; When the second hydraulic linkage valve solution is adopted, the second hydraulic linkage valve (17) comprises a one-way valve and a two-position two-way linkage valve having a T port and an A port, the second oil circuit (A2) is simultaneously connected to the A port and the second oil chamber (Q2) through the one-way valve, and the T port is connected to the second oil circuit (A2) or to a low-pressure source (LP); the second oil circuit (A2) is connected to the valve core driving chamber of the two-position two-way valve, when the second oil circuit (A2) is connected to the high-pressure source (HP), the T port is disconnected from the A port; when the second oil circuit (A2) is connected to the low-pressure source (LP), the T port is connected to the A port; When the third hydraulic linkage valve solution is adopted, the third hydraulic linkage valve (18) includes a one-way valve and a linkage piston rod (19); the second oil circuit (A2) is connected to the second oil chamber (Q2) through the one-way valve; the second oil circuit (A2) is connected to the drive chamber of the linkage piston rod (19); when the second oil circuit (A2) is connected to a high-pressure source (HP), the linkage piston rod (19) does not contact the one-way valve core; when the second oil circuit (A2) is connected to a low-pressure source (LP), the linkage piston rod (19) pushes the one-way valve core to be in an open state.

5. The high-efficiency multi-stage braking mechanism according to claim 2, characterized in that: The hydraulic control unit uses at least one hydraulic valve, the P port of the hydraulic valve is connected to the high pressure source, and the T port of the hydraulic valve is connected to the low pressure source; The first solution is to use a two-position three-way valve, whose port A is connected to the first oil circuit (A1) and the second oil circuit (A2). When the valve core is in the first position, port A is connected to port T and port P is blocked; when the valve core is in the second position, port A is connected to port P and port T is blocked. The second scheme: a two-position four-way valve is used, wherein the A port is connected to the first oil circuit (A1) and the second oil circuit (A2), and the B port is connected to the third oil circuit (A3). When the valve core is in the first position, the A port is connected to the T port, and the B port is connected to the P port; when the valve core is in the second position, the A port is connected to the P port, and the B port is connected to the T port; the third scheme: a two-position four-way valve is used, wherein the A port is connected to the first oil circuit (A1) and the fourth oil circuit (A4), and the B port is connected to the fifth oil circuit (A5). When the valve core is in the first position, the A port and the B port are both connected to the T port, and the P port is blocked; when the valve core is in the second position, the A port is connected to the P port, and the B port and the T port are both blocked; The fourth scheme: a two-position five-way valve is used, wherein port A is connected to the first oil circuit (A1) and the fourth oil circuit (A4), port B is connected to the fifth oil circuit (A5), and port C is connected to the third oil circuit (A3). When the valve core is in the first position, ports A and B are both connected to port T, and port C is connected to port P; when the valve core is in the second position, port A is connected to port P, port B is blocked, and port C is connected to port T. When any one of the first to fourth solutions is adopted, when the engine needs to operate in the failure mode, the valve core is switched to the first position; when the engine needs to operate in the first effective mode, the valve core is switched to the second position; The fifth scheme: a three-position four-way valve is used, wherein port A is connected to the first oil circuit (A1), and port B is connected to the second oil circuit (A2). When the valve core is in the first position, ports A and B are both connected to port T, and port P is blocked; when the valve core is in the second position, port B is connected to port P, and port A is connected to port T; when the valve core is in the third position, ports A and B are both connected to port P, and port T is blocked; Scheme 6: A three-position five-way valve is used, wherein port A is connected to the first oil circuit (A1), port B is connected to the fourth oil circuit (A4), and port C is connected to the fifth oil circuit (A5); when the valve core is in the first position, ports A and C are both connected to port T, port P is blocked, and port B is connected to port T or port B is blocked; when the valve core is in the second position, port B is connected to port P, port C is blocked, and port A is connected to port T; when the valve core is in the third position, ports A and B are both connected to port P, and ports C and T are both blocked; The seventh scheme: a three-position five-way valve is used, wherein port A is connected to the first oil circuit (A1), port B is connected to the second oil circuit (A2), and port C is connected to the third oil circuit (A3). When the valve core is in the first position, ports A and B are both connected to port T, and port C is connected to port P; when the valve core is in the second position, ports B and C are both connected to port P, and port A is connected to port T; when the valve core is in the third position, ports A and B are both connected to port P, and port C is connected to port T. An eighth solution: a three-position six-way valve is used, wherein port A is connected to the first oil circuit (A1), port B is connected to the fourth oil circuit (A4), port C is connected to the fifth oil circuit (A5), and port D is connected to the third oil circuit (A3); when the valve core is in the first position, ports A and C are both connected to port T, port B is blocked or connected to port T, and port D is connected to port P; when the valve core is in the second position, ports B and D are both connected to port P, port C is blocked, and port A is connected to port T; when the valve core is in the third position, ports A and B are both connected to port P, port C is blocked, and port D is connected to port T; When any one of the fifth to eighth solutions is adopted, when the engine needs to operate in the failure mode, the valve core is switched to the first position; When the engine needs to run in the second effective mode, the valve core is switched to the second position; When the engine needs to run in the first effective mode, the valve core is switched to the third position; Ninth solution: two two-position three-way valves are used, the A port of the first two-position three-way valve is connected to the first oil circuit (A1), when the valve core is in the first position, the A port is connected to the T port, and the P port is blocked, when the valve core is in the second position, the A port is connected to the P port, and the T port is blocked; the A port of the second two-position three-way valve is connected to the second oil circuit (A2), when the valve core is in the first position, the A port is connected to the T port, and the P port is blocked, when the valve core is in the second position, the A port is connected to the P port, and the T port is blocked; when the engine needs to run in the failure mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to the first position; when the engine needs to run in the second effective mode, the first two-position three-way valve is switched to the first position, and the valve core of the second two-position three-way valve is switched to the second position; When the engine needs to run in the first effective mode, the valve cores of the first two-position three-way valve and the second two-position three-way valve are switched to the second position; The tenth scheme: a two-position three-way valve and a two-position four-way valve are used, the A port of the two-position three-way valve is connected to the second oil circuit (A2), when the valve core is in the first position, the A port is connected to the T port, and the P port is blocked, when the valve core is in the second position, the A port is connected to the P port, and the T port is blocked; the A port of the two-position four-way valve is connected to the first oil circuit (A1), the B port of the two-position four-way valve is connected to the third oil circuit (A3), when the valve core is in the first position, the A port is connected to the T port, and the B port is connected to the P port; when the valve core is in the second position, the A port is connected to the P port, and the B port is connected to the T port; When the engine needs to run in the failure mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the first position; when the engine needs to run in the second effective mode, the two-position three-way valve is switched to the second position, and the valve core of the two-position four-way valve is switched to the first position; when the engine needs to run in the first effective mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the second position; The eleventh scheme: a two-position three-way valve and a two-position four-way valve are used, and the port A of the two-position three-way valve is connected to the first oil circuit (A1). When the valve core is in the first position, the port A is connected to the port T, and the port P is blocked. When the valve core is in the second position, the port A is connected to the port P, and the port T is blocked. The port A of the two-position four-way valve is connected to the fourth oil circuit (A4), and the port B is connected to the fifth oil circuit (A5). When the valve core is in the first position, the port A is blocked or connected to the port T, and the port B is connected to the port T, and the port P is blocked. When the valve core is in the second position, the port A is connected to the port P, and both the port B and the port T are blocked. When the engine needs to run in the failure mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the first position; when the engine needs to run in the second effective mode, the two-position three-way valve is switched to the first position, and the valve core of the two-position four-way valve is switched to the second position; when the engine needs to run in the first effective mode, the valve cores of the two-position three-way valve and the two-position four-way valve are switched to the second position; The twelfth scheme: two two-position four-way valves are used, the first two-position four-way valve A port is connected to the first oil circuit, the B port is connected to the third oil circuit, when the valve core is in the first position, the A port is connected to the T port, the B port is connected to the P port, when the valve core is in the second position, the A port is connected to the P port, the B port is connected to the T port; the second two-position four-way valve A port is connected to the fourth oil circuit, the B port is connected to the fifth oil circuit, when the valve core is in the first position, the A port is blocked or connected to the T port, the B port is connected to the T port, and the P port is blocked; when the valve core is in the second position, the A port is connected to the P port, and the B port and the T port are both blocked; when the engine needs to run in the failure mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to the first position; when the engine needs to run in the second effective mode, the first two-position four-way valve is switched to the first position, and the valve core of the second two-position four-way valve is switched to the second position; When the engine needs to run in the first effective mode, the valve cores of the first two-position four-way valve and the second two-position four-way valve are switched to the second position.

6. The high-efficiency multi-stage braking mechanism according to claim 3, characterized in that: The guide mechanism arranged between the plunger and the plunger sleeve includes a guide vertical groove arranged on the outer wall surface of the plunger or a guide vertical groove arranged on the inner wall surface of the plunger sleeve; when the guide vertical groove is arranged on the outer wall surface of the plunger, the corresponding end of the locking body or the guide body added to the plunger sleeve always extends into the guide vertical groove; when the guide vertical groove is arranged on the inner wall surface of the plunger sleeve, the corresponding end of the spring seat or the guide body added to the plunger always extends into the guide vertical groove.

7. The high-efficiency multi-stage braking mechanism according to claim 1 or 6, characterized in that: When it is necessary to limit the rotational movement of the plunger sleeve relative to the shell, a second guide mechanism is provided between the plunger sleeve and the shell, and the second guide mechanism includes a guide vertical groove provided on the inner wall surface of the shell or a guide vertical groove provided on the outer wall surface of the plunger sleeve. When the guide vertical groove is provided on the inner wall surface of the shell, the corresponding end of the locking body or the guide body added to the plunger sleeve always extends into the guide vertical groove; when the guide vertical groove is provided on the outer wall surface of the plunger sleeve, the guide body added to the shell always extends into the guide vertical groove; guide vertical grooves are provided on both the outer wall surface of the plunger and the inner wall surface of the shell, and the two ends of the corresponding locking body or the guide body added to the plunger sleeve always extend into the above-mentioned guide vertical grooves, thereby realizing guidance among the shell, the plunger sleeve and the plunger.

8. The high-efficiency multi-stage braking mechanism according to claim 7, characterized in that: The side wall surface of the locking body in contact with the circumferential groove is processed into an arc surface or a plane with a preset curvature radius. The locking body is provided with an anti-rotation mechanism, including a clamping ring arranged in the groove on the locking body or its cooperation with the guide vertical groove.

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