CN210530942U - Compression release type in-cylinder brake device for engine - Google Patents

Abstract

The utility model discloses a compression release formula engine in-cylinder arresting gear, include: the camshaft is provided with a plurality of exhaust cams; the camshaft is provided with an oil through cavity along the axial direction, the oil through cavity is communicated with the oil supply device through the rotary oil inlet interface device, the exhaust cam is provided with a mounting hole along the radial direction, and a sliding plunger mechanism is arranged in the mounting hole; when the electromagnetic directional valve is powered off, the oil through cavity is communicated with the oil pan through the pressure relief oil way and is communicated with the engine oil way through the pressure relief oil way; when the electromagnetic directional valve is electrified, the oil path supplies oil to the oil passage chamber through the one-way oil path, and the sliding plunger mechanism extends out of the cam surface of the exhaust cam to form a braking bulge when not blocked by the tappet. Compared with the prior art, the sliding plunger extends out of the cam surface of the exhaust cam only when the engine is in the in-cylinder braking mode, so that the reliability of the engine is higher, the oil supply device can push the sliding plunger mechanism to act only by the pressure of an engine oil way without a supercharging mechanism, and the structure is simpler.

Description

Compression release type in-cylinder brake device for engine

Technical Field

The utility model relates to an in-cylinder brake technical field especially relates to a compression release formula in-cylinder brake equipment.

Background

The in-cylinder braking technology of the engine mainly goes through the development processes of exhaust butterfly valve braking, air-release braking, compression release braking and the like, wherein the compression release braking technology is the best technology of the braking performance of the engine at present, and the basic principle is as follows: when the engine is dragged backwards, the piston compresses the gas in the cylinder to generate braking power in the process of ascending the compression stroke piston. Before the compression top dead center, the compression release type brake device drives the exhaust valve to open a certain opening degree, compressed high-temperature and high-pressure charging in the cylinder is discharged, at the moment, the pressure in the cylinder is rapidly reduced, after a certain crank angle, the exhaust valve is closed again, the piston moves downwards, and as the charging in the cylinder is greatly reduced, the working of the charging in the cylinder on the piston is also greatly reduced, and the counter braking power of the compression charging in the cylinder on the piston is reduced or eliminated.

Compression release braking technology, generally combined with exhaust butterfly valve braking, during the exhaust stroke, the exhaust passage of the engine is closed by the butterfly valve, back pressure is established, and the piston is subjected to the pressure of gas during the upward process, so that the upward speed is reduced, the power loss of the piston is increased, and the braking power is generated again.

Chinese utility model patent CN201241740Y discloses a four-stroke internal combustion engine rocking arm integrated form arresting gear, it sets up two braking archs on the control cam for realize opening the (air) intake valve before the intake stroke finishes and increase the air input, open the cylinder braking that the exhaust valve released pressure realized the engine before the compression stroke finishes, in order to offset the valve lift that the arch arouses of braking when the engine normal operating, need set up hydraulic control's clearance compensation mechanism on the rocking arm. Because the normal operating state accounts for the vast majority of the operating state of the whole engine, the clearance compensation mechanism is in the working state in the vast majority of the operating time of the engine, higher requirements on reliability and the like are provided, and the structure is more complex.

SUMMERY OF THE UTILITY MODEL

The above-mentioned not enough to prior art, the utility model provides a compression release formula engine cylinder internal braking device to improve the reliability of engine work.

In order to solve the technical problem, the utility model discloses a compression release formula engine in-cylinder arresting gear, include: the valve actuating mechanism comprises a camshaft, and the camshaft is provided with a plurality of exhaust cams; the exhaust cam is provided with a mounting hole along the radial direction, the mounting hole is communicated with the oil through cavity, and a sliding plunger mechanism is arranged in the mounting hole; the oil supply device comprises an electromagnetic directional valve, a pressure relief oil way and a one-way oil way, and when the electromagnetic directional valve is powered off, the oil through cavity is communicated with the oil pan through the pressure relief oil way and is communicated with an engine oil way through the pressure relief oil way; when the electromagnetic directional valve is electrified, the oil path of the engine supplies oil to the oil through cavity through the one-way oil path, and the sliding plunger mechanism extends out of the cam surface of the exhaust cam to form a braking bulge when not blocked by a tappet or a valve protective cap of the valve mechanism.

Wherein, the sliding plunger mechanism comprises a sliding plunger, a plunger return spring, a pin shaft and a plug, the mounting hole is a stepped hole, the stepped hole comprises a big hole and a small hole, the small hole radially penetrates through the part of the cam shaft at one side of the oil through cavity and forms a blind hole at the part of the cam shaft at the other side of the oil through cavity, the big hole is sunken from the oil through cavity to the opening direction of the small hole, the pin shaft is mounted in the big hole, the sliding plunger is mounted in the small hole, the sliding plunger is axially provided with a spring mounting hole and radially provided with a slotted hole, the pin shaft is slidably arranged in the slotted hole, the plunger return spring is clamped in the spring mounting hole by the pin shaft, when the oil through cavity is in a pressure relief state, the plunger return spring pushes the sliding plunger against the bottom of the blind hole, the plug is screwed at the outer opening end of the spring mounting hole and seals the spring mounting hole.

The rotary oil inlet interface device is arranged at the opening end part of the oil through cavity.

The rotary oil inlet interface device comprises a fixed oil sleeve, the camshaft is provided with an oil inlet shaft neck, the oil inlet shaft neck is rotatably and hermetically mounted on the fixed oil sleeve, an annular oil groove is formed in the peripheral surface of the oil inlet shaft neck, the annular oil groove is communicated with the oil through cavity, the fixed oil sleeve is provided with an oil through hole, and the oil through hole is communicated with the annular oil groove.

And the end part of the camshaft is provided with an end cover for sealing the opening of the oil through cavity.

Wherein the end cap is provided with an annular flange for limiting axial movement of the stationary oil jacket.

Wherein, the electromagnetic directional valve is a two-position three-way electromagnetic directional valve.

Wherein, be provided with the check valve in the one-way oil circuit.

And a pressure reducing valve is arranged in the pressure reducing oil path.

And an overflow pressure retaining valve is arranged in the pressure relief oil way.

The structure of the overflow pressure retaining valve is the same as that of the pressure reducing valve.

The pressure reducing valve comprises a valve body, the valve body is provided with a valve cavity, the valve cavity is provided with an oil inlet, an oil outlet and a pressure regulating port, a valve ball and a pressure regulating spring are installed in the valve cavity, a pressure regulating screw is screwed in the pressure regulating port, and the valve ball is elastically pressed against the oil inlet.

The oil inlet cavity is divided into two parts by the plug, two ends of the oil inlet cavity are respectively provided with a rotary oil inlet interface device, and the rotary oil inlet interface devices are respectively communicated with one oil supply device for supplying oil respectively.

The rotary oil inlet interface device is arranged at an installation shaft neck of the camshaft and comprises a camshaft seat, a bearing bush is arranged in the camshaft seat, the installation shaft neck is rotatably and hermetically arranged on the bearing bush, an annular oil groove is formed in the peripheral surface of the installation shaft neck, the annular oil groove is communicated with the oil through cavity, oil through holes communicated with the annular oil groove are formed in the camshaft seat and the bearing bush, and a plug is arranged at the opening end of the oil through cavity.

After the technical scheme is adopted, the utility model has the technical effects that when the engine is in a normal working mode, the electromagnetic directional valve is powered off, the oil through cavity is communicated with the oil bottom shell through the pressure relief oil way and is communicated with the engine oil way through the pressure relief oil way, and the oil pressure in the oil through cavity is not enough to push the sliding plunger mechanism to act; when the engine enters an in-cylinder braking mode, the electromagnetic directional valve is electrified, the oil circuit of the engine supplies oil to the oil through cavity through the one-way oil circuit, the sliding plunger mechanism extends out of the cam surface of the exhaust cam to form a braking bulge when not blocked by a tappet or a valve protective cap of the valve mechanism, and the braking bulge pushes the valve tappet or the valve protective cap to open an exhaust valve, so that in-cylinder braking is completed. Compared with the prior art, the sliding plunger extends out of the cam surface of the exhaust cam only when the engine is in the in-cylinder braking mode, the working time of the sliding plunger mechanism is very short, and when the engine is in the normal working state, the sliding plunger is recovered in the mounting hole of the exhaust cam, the whole exhaust cam is like a common exhaust cam, the working reliability of the engine is higher, and the oil supply device can push the sliding plunger mechanism to act only by the pressure of an oil circuit without adopting a supercharging mechanism, so the structure is simpler. The utility model is suitable for a camshaft underlying engine also is applicable to camshaft overhead engine.

Drawings

FIG. 1 is a schematic structural view of an embodiment 1 of the compression-release engine in-cylinder brake apparatus of the present invention;

FIG. 2 is a hydraulic schematic of the oil supply of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 1 at I;

FIG. 4 is a reference view showing an operation state when the sliding plunger is extended in embodiment 1 shown in FIG. 1;

FIG. 5 is a cross-sectional view taken at A-A of FIG. 1;

FIG. 6 is a schematic view of the portion of the cam shaft of FIG. 3 with the sliding plunger mechanism removed;

FIG. 7 is a cross-sectional view of the relief valve of FIG. 2;

fig. 8 is a reference view showing an operating state in which the sliding plunger mechanism is in a position opposed to the lifter in normal operation of the engine in embodiment 1;

fig. 9 is a reference view showing an operating state in which the sliding plunger mechanism is in a position deviated from the tappet position in the normal operation of the engine in embodiment 1;

fig. 10 is a reference diagram of an operating state of the sliding plunger mechanism at a position opposed to the lifter upon entry of the engine into the in-cylinder braking mode in embodiment 1;

fig. 11 is a reference diagram of an operating state of the sliding plunger mechanism at the position deviated from the lifter position when the engine is in the in-cylinder braking mode in embodiment 1;

fig. 12 is a reference view showing an operating state in which the sliding plunger mechanism is extended and returned to a position opposite to the lifter in the in-cylinder braking mode of the engine according to embodiment 1;

FIG. 13 is a schematic structural view of embodiment 2 of the compression-release engine in-cylinder brake apparatus of the present invention;

FIG. 14 is a schematic structural view of embodiment 3 of the compression-release engine in-cylinder brake apparatus of the present invention;

fig. 15 is a schematic position diagram of the sliding plungers of all the cylinders in embodiment 1 in the contact of the tappets with the base circle of the exhaust cam in the in-cylinder braking state;

FIG. 16 is a schematic view showing the positions of the sliding plungers of all the cylinders in embodiment 1 when the tappets are in contact with the sliding plungers in the in-cylinder braking state;

FIG. 17 is a schematic diagram showing the positions of the sliding plungers of the 1 cylinder, the 2 cylinder and the 3 cylinder in the braking state in the cylinders in the embodiment 2;

FIG. 18 is a schematic diagram showing the positions of 4-, 5-and 6-cylinder sliding plungers in an in-cylinder braking state in embodiment 2;

in the figure: 10-exhaust valve, 11-valve spring, 12-valve rocker arm, 13-rocker arm shaft, 14-push rod, 15-tappet, 20-camshaft, 21-intake cam, 22-exhaust cam, 221-base circle, 23-oil through cavity, 24-annular oil groove, 25-timing gear, 26-plug, 27-plug, 28-mounting journal, 281-annular oil groove, 30-rotary oil inlet interface device, 31-end cover, 32-fixed oil sleeve, 321-oil through hole, 40-pressure reducing valve, 41-valve body, 42-valve ball, 43-pressure regulating spring, 44-pressure regulating screw, P1-oil inlet, P2-oil outlet, 50-overflow pressure retaining valve, 60-oil bottom shell, 70-sliding plunger mechanism, 71-sliding plunger, 711-spring mounting hole, 712-long slotted hole, 72-plunger return spring, 73-pin shaft, 74-plug, 80-electromagnetic directional valve, phi x-big hole, phi y-small hole, 90-rotary oil inlet interface device, 91-camshaft seat, 92-bearing bush, 93-end cover, 94-sealing ring, 911-oil through hole and 100-one-way valve.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

Example 1

In the present embodiment, taking a six-cylinder four-stroke engine as an example, as shown in fig. 1, in a compression-release type engine in-cylinder brake device, a valve rocker arm 12 is rotatably mounted on a rocker shaft 13, a push rod 14 and an exhaust valve 10 are respectively disposed at two sides of the rocker shaft 13, when a tappet 15 and the push rod 14 push the valve rocker arm 12 from one side to swing around the rocker shaft 13 under the action of an exhaust cam 22 of a camshaft 20, the other side of the valve rocker arm 12 presses the exhaust valve 10 to open the valve; when the camshaft rotates a specified angle, the exhaust valve 10 returns under the action of the valve spring 11, and the valve is closed. Camshaft 20 is held in synchronization with the engine crankshaft by timing gear 25.

The above structure is a part for controlling the motion of the exhaust valve in the valve train of the engine, and the camshaft 20 is further provided with a plurality of intake cams 21 for controlling the opening and closing of the corresponding intake valves, which are not described herein.

As shown in fig. 1, an oil through cavity 23 is axially formed in the camshaft 20, the camshaft 20 is provided with a rotary oil inlet interface device 30, the oil through cavity 23 is communicated with an oil supply device through the rotary oil inlet interface device 30, the exhaust cam 22 is radially provided with a mounting hole, the mounting hole is communicated with the oil through cavity 23, and a sliding plunger mechanism 70 is arranged in the mounting hole.

As shown in fig. 2, the oil supply device includes an electromagnetic directional valve 80, a pressure relief oil path and a one-way oil path, and when the electromagnetic directional valve 80 is powered off, the oil through cavity 23 is communicated with the oil pan 60 through the pressure relief oil path and is communicated with an engine oil path through the pressure relief oil path; when the electromagnetic directional valve 80 is electrified, the engine oil path supplies oil to the oil passing chamber 23 through the one-way oil path, and the sliding plunger mechanism 70 extends out of the cam surface of the exhaust cam 22 to form a braking bulge when not blocked by the tappet 15 or the valve cap of the valve train.

Preferably, the electromagnetic directional valve 80 is a two-position three-way electromagnetic directional valve, an overflow pressure retaining valve 50 is arranged in the pressure relief oil path, a one-way valve 100 is arranged in the one-way oil path, and a pressure reducing valve 40 is arranged in the pressure relief oil path.

The pressure reducing valve 40 can adopt a structure of a common pressure reducing valve, and can also adopt a new structure based on cost consideration, as shown in fig. 7, a valve cavity is formed in a valve body 41, an oil inlet P1, an oil outlet P2 and a pressure regulating port are formed in the valve cavity, a valve ball 42 and a pressure regulating spring 43 are installed in the valve cavity, a pressure regulating screw 44 is screwed in the pressure regulating port, and the valve ball 42 is elastically pressed against the oil inlet. The working principle of the pressure reducing valve 40 is as follows:

setting: the elastic force of the pressure regulating spring 43 is F;

the pressure of the oil inlet P1 on the valve ball 42 is N1;

the pressure of the oil outlet P2 on the valve ball 42 is N2;

the force with which the sealing valve ball opens is then: f + N2 ═ N1, N2< N1;

the size of the pressure regulating spring 43 is adjusted through the pressure regulating screw 44, so that the size of N2 can be changed, namely the size of the oil pressure of the oil outlet P2 is changed.

The relief pressure retaining valve 50 may be constructed as a conventional relief valve or as the pressure reducing valve 40.

As shown in fig. 3, 4, 5 and 6, the sliding plunger mechanism 70 includes a sliding plunger 71, a plunger return spring 72, a pin 73 and a plug 74, the mounting hole is a stepped hole, the stepped hole includes a large hole Φ x and a small hole Φ y, the small hole Φ y radially penetrates through the portion of the camshaft on one side of the oil chamber 23 and forms a blind hole on the portion of the camshaft on the other side of the oil chamber 23, the large hole Φ x is recessed from the opening direction of the oil chamber 23 to the small hole Φ y, the pin 73 is mounted in the large hole Φ x, the sliding plunger 71 is mounted in the small hole Φ y, the sliding plunger 71 is axially provided with a spring mounting hole 711 and radially provided with a long slot 712, the pin 73 is slidably disposed in the long slot 712, the plunger return spring 72 is clamped in the spring mounting hole by the pin 73, when the oil chamber 23 is in a pressure relief state, the plunger return spring 72 pushes the sliding plunger 71 against the bottom of the blind hole 711, the plug 74 is screwed to the outer opening end of the spring mounting hole 711 and seals the spring mounting hole 711.

During assembly, the sliding plunger 71 is firstly installed from the small hole phi y, the plunger return spring 72 is installed into the spring installation hole 711, the plunger return spring 72 is compressed, the pin shaft 73 is installed in place from the oil through cavity 23, then the plunger return spring 72 is loosened, the pin shaft 73 is clamped into the large hole phi x, and finally the screw plug 74 is screwed to seal the spring installation hole 711.

As shown in fig. 1, the rotary oil inlet interface device 30 is disposed at an opening end of the oil through cavity 23, the rotary oil inlet interface device 30 includes a fixed oil sleeve 32 and an end cover 31, the camshaft 20 is provided with an oil inlet journal, the oil inlet journal is rotatably and sealingly mounted on the fixed oil sleeve 32, an annular oil groove 24 is disposed on an outer circumferential surface of the oil inlet journal, the annular oil groove 24 is communicated with the oil through cavity 23, the fixed oil sleeve 32 is provided with an oil through hole 321, and the oil through hole 321 is communicated with the annular oil groove 24. The end cover 31 is provided at the end of the camshaft 20 for sealing the opening of the oil passage chamber 23, and the end cover 31 is further provided with an annular flange for restricting the axial movement of the stationary oil jacket 32.

In the present invention, the annular oil groove 24 may not be provided on the outer peripheral surface of the oil inlet journal but on the inner peripheral surface of the fixed oil jacket 32. When the camshaft 20 rotates, the annular oil groove 24 can communicate the hydraulic oil from the high-pressure oil passage with the oil communication chamber 23.

The utility model discloses a theory of operation is:

when the electromagnetic directional valve 80 is powered off, the oil communicating cavity 23 is communicated with the oil pan 60 through the electromagnetic directional valve 80 and the overflow pressure retaining valve 50, and is communicated with the engine oil circuit through the pressure reducing valve 40.

The holding pressure of the relief pressure holding valve 50 is equal to or slightly lower than the pressure after decompression of the decompression valve 40, and the magnitude thereof is not larger than the pressure of the hydraulic oil that pushes the slide plunger 71 to move against the elastic force of the plunger return spring 72.

When the electromagnetic directional valve 80 is electrified, the oil through cavity 23 is communicated with the engine oil way through the electromagnetic directional valve 80 and the one-way valve 100.

A plunger return spring 72 in the sliding plunger mechanism is designed to ensure that when the oil pressure of the oil through cavity 23 is the oil pressure of an oil outlet P2 of the pressure reducing valve 40, the thrust generated by the oil pressure on the sliding plunger 71 is smaller than the elastic force of the plunger return spring 72; when the oil pressure in the oil passage chamber 23 is the oil pressure in the oil inlet P1 of the pressure reducing valve 40, the thrust force of the oil pressure to the slide plunger 71 is larger than the elastic force of the plunger return spring 72.

When the engine normally works, the electromagnetic directional valve 80 is powered off, the pressure of the oil through cavity 23 of the camshaft 20 is the oil pressure of the oil outlet P2 of the pressure reducing valve 40, the thrust force on the sliding plunger 71 cannot overcome the elastic force of the plunger return spring 72, and the sliding plunger 71 does not move, as shown in fig. 8 and 9.

When the engine enters an in-cylinder braking state, the electromagnetic directional valve 80 is electrified, the engine oil pressure enters the oil through cavity 23 through the check valve 100 and the electromagnetic directional valve 80, the oil pressure of the oil through cavity 23 is the oil pressure of an oil inlet P1 of the pressure reducing valve 40, the thrust of the oil pressure on the sliding plunger 71 overcomes the elastic force of the plunger return spring 72, the sliding plunger 71 moves, as shown in FIG. 10, the thrust of the oil pressure of the oil through cavity 23 on the sliding plunger 71 is smaller than the resultant force of the plunger return spring 72 and the valve spring 11, and the top of the sliding plunger 71 is in contact with the valve tappet 15 but cannot push the tappet 15 to move; the exhaust cam 22 continues to rotate to the position shown in fig. 11, at which time the sliding plunger 71 continues to move under the oil pressure in the inlet port P1 of the pressure reducing valve 40, with the top portion bulging out of the cam surface. When the tappet continues to rotate to the position shown in fig. 12, the oil through chamber 23 becomes a closed space due to the action of the check valve 100, and due to the incompressibility of the hydraulic oil, the sliding plunger 71 will remain at the convex position to drive the tappet 15 to move, and the pressure is released.

The engine of the present embodiment is a six-cylinder four-stroke engine, and as shown in fig. 15 and 16, since the sliding plungers 71 of six cylinders are simultaneously operated, those sliding plungers 71 which hit the lifter 15 or the valve cap (camshaft overhead structure) are blocked in the mounting holes, and only when all the lifters 15 or valve caps of six cylinders are in contact with the base circle 221 of the exhaust cam 22, there is a possibility that the sliding plungers 71 in the exhaust cam 22 are ejected without being blocked by the lifter 15 or the valve cap. Once the sliding plunger 71 is ejected, the sliding plunger 71 maintains the raised position even if the tappet 15 or the valve cap is encountered again, since the oil through chamber 23 is closed.

Example 2

As shown in fig. 13, the structure is basically the same as that of embodiment 1, except that a plug 26 is disposed in the middle of the oil passage chamber 23, the plug 26 divides the oil passage chamber 23 into two parts, two ends of the oil passage chamber 23 are respectively provided with a rotary oil inlet interface device 30, and the rotary oil inlet interface devices 30 are respectively communicated with one of the oil supply devices for supplying oil. Relative position of the sliding plungers 71 of the respective cylinders referring to fig. 17 and 18, wherein fig. 17 is a reference view of relative positions of the sliding plungers 71 of the 1-cylinder, 2-cylinder and 3-cylinder cylinders in the in-cylinder braking mode, and fig. 18 is a reference view of relative positions of the sliding plungers 71 of the 4-cylinder, 5-cylinder and 6-cylinder cylinders in the in-cylinder braking mode, compared with the embodiment shown in fig. 15 and 16, the arc of the base circle 221 between the two sliding plungers 71 is longer in each portion of fig. 17 and 18, that is, all the tappets 15 are in contact with the base circle 221 at the same time, and the sliding plungers 71 are protruded to form braking protrusions more quickly after entering the in-cylinder braking state, so that the operation is more reliable.

Example 3

The structure of the rotary oil inlet interface device is basically the same as that of the rotary oil inlet interface device in embodiment 1, but the mounting position of the rotary oil inlet interface device is different. As shown in fig. 14, the rotary oil inlet interface device 90 is disposed at the mounting journal 28 of the camshaft 20, end caps 93 are disposed at two sides of the camshaft seat 91, a bearing bush 92 is disposed in the camshaft seat 91, the mounting journal 28 is rotatably mounted in the bearing bush 92, and a sealing ring 94 is used for achieving oil sealing of the rotating pair. The outer peripheral surface of the mounting journal 28 is provided with an annular oil groove 281, the annular oil groove 281 is communicated with the oil through cavity 23, the camshaft seat 91 and the bearing bush 92 are provided with an oil through hole 911 communicated with the annular oil groove 281, and the opening end of the oil through cavity is provided with a plug 27. The structure of the position of the lubricating oil hole of the original camshaft mounting journal can be modified by the implementation mode, and the structure is more compact.

The utility model is suitable for a put formula engine under the camshaft, also be applicable to camshaft overhead formula engine, when using in camshaft overhead formula engine, with the cam contact be the valve helmet, rather than the tappet.

The present invention is not limited to the above embodiments, and all improvements based on the concept, principle, structure and method of the present invention will fall within the protection scope of the present invention.

Claims (14)

1. A compression-release in-cylinder brake apparatus for an engine, comprising:

the valve actuating mechanism comprises a camshaft, and the camshaft is provided with a plurality of exhaust cams; it is characterized in that the preparation method is characterized in that,

the exhaust cam is provided with a mounting hole along the radial direction, the mounting hole is communicated with the oil through cavity, and a sliding plunger mechanism is arranged in the mounting hole;

the oil supply device comprises an electromagnetic directional valve, a pressure relief oil way and a one-way oil way, and when the electromagnetic directional valve is powered off, the oil through cavity is communicated with the oil pan through the pressure relief oil way and is communicated with an engine oil way through the pressure relief oil way; when the electromagnetic directional valve is electrified, the oil path of the engine supplies oil to the oil through cavity through the one-way oil path, and the sliding plunger mechanism extends out of the cam surface of the exhaust cam to form a braking bulge when not blocked by a tappet or a valve protective cap of the valve mechanism.

2. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein said sliding plunger mechanism includes a sliding plunger, a plunger return spring, a pin and a plug, said mounting hole is a stepped hole, said stepped hole includes a large hole and a small hole, said small hole radially penetrates a portion of said camshaft on one side of said oil passage chamber and forms a blind hole in a portion of said camshaft on the other side of said oil passage chamber, said large hole is recessed from said oil passage chamber toward an opening direction of said small hole, said pin is mounted in said large hole, said sliding plunger is mounted in said small hole, said sliding plunger is axially provided with a spring mounting hole and radially provided with a long groove hole, said pin is slidably provided in said long groove hole, said plunger return spring is sandwiched in said spring mounting hole by said pin, when said oil passage chamber is in a pressure-released state, the plunger return spring enables the sliding plunger to abut against the bottom of the blind hole, and the plug is screwed at the outer opening end of the spring mounting hole and seals the spring mounting hole.

3. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein said rotary oil-intake interface means is provided at an open end of said oil-through chamber.

4. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein said rotary oil inlet interface means includes a fixed oil jacket, said camshaft is provided with an oil inlet journal, said oil inlet journal is rotatably and sealingly mounted to said fixed oil jacket, an annular oil groove is formed in an outer circumferential surface of said oil inlet journal, said annular oil groove is communicated with said oil through cavity, said fixed oil jacket is formed with an oil through hole, and said oil through hole is communicated with said annular oil groove.

5. The compression-release engine in-cylinder brake apparatus as defined in claim 4, wherein an end of said camshaft is provided with an end cap sealing an opening of said oil passage chamber.

6. The compression-release engine in-cylinder brake apparatus as defined in claim 5, wherein said end cap provides an annular flange for limiting axial movement of said stationary oil jacket.

7. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein said electromagnetic directional valve is a two-position three-way electromagnetic directional valve.

8. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein a check valve is provided in said check oil passage.

9. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein a pressure-reducing valve is provided in said pressure-reducing oil passage.

10. The compression-release engine in-cylinder brake apparatus according to claim 9, wherein an overflow pressure retaining valve is provided in the pressure-release oil passage.

11. The compression-release engine in-cylinder brake apparatus as defined in claim 10, wherein the relief pressure retaining valve has the same structure as the pressure reducing valve.

12. The compression-release engine in-cylinder brake apparatus as defined in claim 11, wherein said pressure-reducing valve includes a valve body, said valve body defines a valve cavity, said valve cavity defines an oil inlet, an oil outlet and a pressure-regulating port, said valve cavity is internally installed with a valve ball and a pressure-regulating spring, said pressure-regulating port is screwed with a pressure-regulating screw, and said valve ball is elastically pressed against said oil inlet.

13. The compression-release engine in-cylinder brake apparatus as defined in claim 1, wherein a plug is disposed in the middle of said oil through cavity, said plug divides said oil through cavity into two parts, and two ends of said oil through cavity are respectively disposed with oil-in-rotation interface devices, said oil-in-rotation interface devices are respectively communicated with one of said oil supply devices for supplying oil.

14. The in-cylinder brake device according to claim 1, wherein the rotary oil inlet interface device is disposed at a mounting journal of the camshaft, the rotary oil inlet interface device includes a camshaft seat, a bearing bush is disposed in the camshaft seat, the mounting journal is rotatably and sealingly mounted to the bearing bush, an annular oil groove is formed in an outer circumferential surface of the mounting journal, the annular oil groove is communicated with the oil passage cavity, the camshaft seat and the bearing bush are provided with oil passage holes communicated with the annular oil groove, and an opening end of the oil passage hole is provided with a plug.

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