CN109356730B

CN109356730B - Switchable push rod type engine braking device

Info

Publication number: CN109356730B
Application number: CN201811462392.8A
Authority: CN
Inventors: 姬腾飞
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-11-28
Filing date: 2018-11-28
Publication date: 2021-07-27
Anticipated expiration: 2038-11-28
Also published as: CN109356730A

Abstract

A switchable push rod type engine braking device comprises a cam shaft, a tappet, a switchable push rod mechanism, a rocker push rod, a rocker mechanism and the like. The switching push rod mechanism comprises an ignition push rod, a brake push rod, a control pull rod, a middle tappet, an electromagnetic valve and the like. The control device is characterized in that a control pull rod is installed in a plunger hole of the controller body, the ignition push rod and the brake push rod respectively penetrate through a hole in the middle of the control pull rod and are driven by the exhaust cam and the brake cam respectively, a middle tappet is arranged in a tappet hole of the controller body, the control pull rod can be driven by lubricating oil to enable the ignition push rod and the brake push rod to be connected with the middle tappet in a switchable manner, when the electromagnetic valve is electrified, the control pull rod enables the brake push rod to be in contact with the middle tappet and enables the exhaust push rod to be withdrawn from contact, the two-stroke engine brake is achieved, the device can ensure that the push rod can be switched only when the exhaust cam and the brake cam are located at a base circle part, and the device is reliable in operation.

Description

Switchable push rod type engine braking device

Technical Field

The invention relates to a switchable push rod type engine braking device, belongs to the technical field of engines, and particularly relates to the technical field of engine braking.

Background

Engine braking technology has been available and used for a long time, particularly in heavy duty diesel engines. For heavy trucks, when long-term braking is required, such as when driving on a long downhill slope, a conventional service brake device (brake) is prone to failure due to overheating during long-term use, and thus greatly threatens the driving safety. When a vehicle equipped with the engine braking device runs, a driver starts the engine braking device according to the requirement, the engine cuts off fuel supply at the moment, the clutch keeps a state of being connected with the power output end of the engine, the vehicle drags the engine to rotate by the kinetic energy of the vehicle, the engine braking device temporarily converts the engine into an air compressor consuming power to realize the braking function by changing the timing and the lift of the valve, particularly the exhaust valve, for heavy trucks, especially when driving on long downhill hills, after starting the engine braking, the driver can control the vehicle to run at a safe speed without stepping on a brake pedal or using a brake less, the working load of the running brake device is greatly relieved, the running safety of the vehicle is greatly improved, and the engine brake device is a necessary configuration for a heavy truck at present.

The engine brake can be divided into compression release type brake and air release type brake, the compression release type brake is that in the compression stroke, when the piston is close to the compression top dead center, the exhaust valve is opened to release the compressed air entering the cylinder, and then the exhaust valve is closed when the piston enters the power stroke after passing through the top dead center. Bleeder braking is where the engine maintains the exhaust valve slightly open during the non-exhaust stroke or only the compression stroke to release compressed air, and generally compression-release braking has a higher braking power and is applied more often than bleeder braking.

At present, an engine braking device is mainly applied to a four-stroke heavy diesel engine, a compression release type engine braking device is used mostly, in one working cycle (air inlet-compression-work doing-air exhaust) of the four-stroke engine, a piston moves upwards once in compression and air exhaust strokes respectively, theoretically, when the engine is converted into a braking state to work, the compression and air exhaust strokes are compressed and released (namely two-stroke engine braking) to generate the highest braking power to the maximum extent, but most of the compression release type engine braking devices applied at present can not change the timing and the lift of an exhaust valve used for normal work of the engine in the air exhaust stroke, therefore, only the air entering an air cylinder can be compressed and released to generate primary braking in one working cycle, and one braking operation cannot be performed again in the exhaust stroke. In the technology disclosed at present, the two-stroke engine braking can be realized by a plurality of rocker arms or complex rocker arms or valve bridge structures, the structure is complex, the cost is high, and the working reliability is insufficient.

Chinese patent applications 201810428991.1 and 201810919167.6 disclose two design schemes of the present inventor regarding to the implementation of two-stroke engine braking, which respectively adopt a sliding cam and a sliding rocker arm to implement two-stroke engine braking, and the two designs focus on the application to an engine with an overhead camshaft, and the present invention provides a design for implementing two-stroke engine braking on an engine with a lower camshaft adopting a push rod type valve train.

Disclosure of Invention

The invention provides a switchable push rod type engine braking device which can realize that a piston is compressed and released to generate braking power in compression and exhaust strokes, namely a two-stroke engine is braked, so that the effect of the engine braking function is exerted to the maximum.

The engine braking device comprises a cam shaft, a tappet, a switchable push rod mechanism, a rocker push rod, a rocker mechanism and the like. The exhaust and intake cams used for the engine to operate in an ignition state are arranged on each cylinder on the cam shaft, the brake cam specially used for the engine to perform braking operation is further included, three lobes are arranged on the brake cam, the smaller two lobes are symmetrically distributed and used for opening the exhaust valve to release compressed gas when the piston operates to the position near the top dead center each time in the engine braking state, and the other larger lobe is used for opening the exhaust valve in the power stroke of the engine to enable waste gas to enter the cylinder so as to realize the purpose of compressing again to release to generate braking in the exhaust stroke.

The exhaust cam and the brake cam of the camshaft are respectively provided with a tappet, a switchable push rod mechanism is arranged above the tappet, and the switchable push rod mechanism comprises an ignition push rod, a brake push rod, a push rod spring, a spring seat, a controller body, a control pull rod, a middle tappet, an electromagnetic valve and the like. The lower ends of the ignition push rod and the brake push rod are spherical, the upper ends of the ignition push rod and the brake push rod are plate-shaped, the top of the plate-shaped is arc-shaped, and push rod springs are arranged on the ignition push rod and the brake push rod, so that a transmission system between a cam shaft and the push rod is always kept in contact in operation. The controller body is arranged on an engine cylinder body or a cylinder cover, the controller body is provided with a plunger hole and a tappet hole, a middle tappet is arranged in the tappet hole of the controller body, the middle tappet is a cylinder, the upper end of the middle tappet is provided with a ball socket, the lower end of the middle tappet is a cuboid, the left side and the right side of the middle tappet are respectively provided with an arc groove, the middle of the middle tappet is provided with a partition plate, the controller body is also provided with a control pull rod, two ends of the control pull rod are cylindrical, the middle of the control pull rod is plate-shaped and provided with two holes, an ignition push rod and a braking push rod respectively penetrate through the two holes of the control pull rod, one end of the ignition push rod and the other end of the ignition push rod are connected with the tappet, the other end of the ignition push rod and the braking push rod are switchably connected with the middle tappet under the control of the control pull rod, one end of the cylinders at two ends of the control pull rod are arranged in the plunger hole of the controller body, the other end of the control pull rod is arranged in a guide hole of the controller body, and the control pull rod can slide left and right in the plunger hole of the controller body, and can push the ignition push rod and the brake push rod to swing left and right at the same time, and a return spring is arranged at the position of the guide hole and can push the control pull rod to slide towards one end of the plunger hole. The plunger hole of the controller body is communicated with a lubricating oil channel with certain pressure of an engine, an electromagnetic valve is arranged on the lubricating oil channel, the control oil channel is communicated and closed, when the electromagnetic valve is opened, the lubricating oil channel is communicated, the pressure of lubricating oil generates acting force on the control pull rod, and the acting force of the lubricating oil on the control pull rod is obviously greater than the force of a return spring, so that the control pull rod can push the ignition push rod and the brake push rod to swing to one side. In addition, the middle tappet, the ignition push rod and the brake push rod are also provided with a guide device to avoid the rotation of the middle tappet, the ignition push rod and the brake push rod.

The rocker arm push rod and the rocker arm mechanism are arranged above the switchable push rod mechanism, one end of the rocker arm push rod is spherical and is connected with a ball socket at the upper end of the middle tappet, and the other end of the rocker arm push rod is a ball socket and is connected with a ball head of an adjusting screw of the rocker arm mechanism and used for driving the rocker arm mechanism to open or close the valve.

The working principle of the device is as follows: when the engine runs in an ignition state, the electromagnetic valve is in a power-off state, the control pull rod is not subjected to the acting force of lubricating oil at the moment, the control pull rod pushes the ignition push rod and the brake push rod to one side of the brake push rod under the action of the return spring, the ignition push rod is in contact with the middle tappet at the moment, the middle tappet pushes the rocker push rod and the exhaust rocker under the driving of the exhaust cam, so that the exhaust valve is opened and closed according to the valve timing and the lift range in the ignition state, the brake push rod is pushed to the position which cannot be in contact with the middle tappet by the control pull rod, and the brake push rod is in an empty reciprocating motion state under the action of the brake cam. When the engine needs to be switched to an engine braking working state, the electromagnetic valve is electrified, engine lubricating oil with certain pressure enters a plunger hole of the controller body to generate acting force on the control pull rod, the ignition push rod and the braking push rod are pushed to swing to one side of the ignition push rod by overcoming the return spring force, at the moment, if the exhaust cam and the braking cam are both positioned at a base circle part, the ignition push rod and the braking push rod do not have lift ranges and are positioned at the lowest positions and have gaps with the middle tappet, at the moment, the control pull rod can smoothly push the ignition push rod and the braking push rod to swing to one side of the ignition push rod, the braking push rod is contacted with the middle tappet, the ignition push rod is separated from the middle tappet, the middle tappet pushes the rocker push rod and the exhaust rocker arm under the driving of the braking cam, and the exhaust valve is opened and closed according to the valve timing and the lift range of the engine braking state, the engine is brought into a braking working state. When the engine needs to quit the braking working state, the electromagnetic valve is powered off, so that lubricating oil in a plunger hole of the controller body is drained, the control pull rod can push the ignition push rod and the braking push rod to one side of the braking push rod under the action of the return spring, at the moment, the ignition push rod and the middle tappet enter a contact state, the middle tappet pushes the rocker push rod and the exhaust rocker under the driving of the exhaust cam, so that the exhaust valve is opened and closed according to the valve timing and the lift range in the ignition state, the engine returns to the ignition running state, and the braking push rod is pushed to a position where the middle tappet cannot be in contact with the control pull rod and is in an empty reciprocating motion state under the action of the braking cam.

In the switching process of the contact and the contact withdrawal between the ignition push rod and the middle tappet as well as the brake push rod and the middle tappet, a key problem is how to avoid that the switching cannot be carried out due to the interference between the push rod and the middle tappet during the switching when the exhaust cam or the brake cam is not positioned at the base circle part (when the ignition push rod or the brake push rod has a certain lift), or the valve system is damaged due to the impact caused by the fact that one push rod is not positioned at the base circle part during the switching (because the lift of the middle tappet, the rocker arm and the valve is suddenly changed to zero when the push rod is not positioned at the base circle part, the great impact is generated on the rocker arm and the valve mechanism), the design scheme of the invention can avoid the problems, ensure that the control pull rod can realize the switching of the contact and the contact withdrawal between the ignition push rod and the brake push rod and the middle tappet only when the exhaust cam and the brake cam are positioned at the base circle part simultaneously, the reliability of the operation of the invention is ensured and the specific principles and procedures for solving this critical problem are described in detail in a first embodiment of the invention, detailed in the detailed description of the embodiment.

Furthermore, the top ends of the ignition push rod and the brake push rod are spherical, and the left side and the right side of the bottom of the middle tappet are ball sockets, so that the manufacturability is improved, and the rotation of the push rod can not be limited.

Furthermore, two middle tappets are arranged on the controller body, the lower portions of the two middle tappets are respectively connected with the ignition push rod and the brake push rod, the upper ends of the two middle tappets are connected with the rocker push rod, the rocker push rod penetrates through a hole in the middle of the control pull rod, the upper end of the rocker push rod is connected with the rocker mechanism, the lower end of the rocker push rod is connected with one of the two middle tappets in a switchable manner, and the control pull rod realizes switching of the engine between the ignition working state and the braking working state by controlling switching of connection between the rocker push rod and the two middle tappets.

Furthermore, the two middle tappets can be directly driven by the exhaust cam and the brake cam, so that parts such as an ignition push rod, a brake push rod and the like can be omitted, and the structure is simplified.

Furthermore, the control pull rod can be directly driven by compressed air or an electromagnetic valve of a vehicle, so that a lubricating oil channel can be avoided, the structure is simplified, the work of the control pull rod is not influenced by the pressure, the temperature and the quality of lubricating oil, and the response speed of the control pull rod can be improved.

Further, the plunger hole portion of the controller body of the present invention is disposed separately from the tappet hole portion, increasing the flexibility of the arrangement of the device.

Furthermore, the switchable push rod mechanism can be simultaneously used for an exhaust valve system and an intake valve system, and a special brake cam can be added on the cam shaft for the intake valve system and the exhaust valve system respectively, so that the engine does not need to suck waste gas into the cylinder again, the engine compresses fresh air every time to realize two-stroke braking by adding one-time opening of the intake valve, and the working temperature of the engine during braking can be reduced.

Drawings

FIG. 1 is a schematic illustration of a first embodiment of the present invention in an ignition operating condition with both the exhaust cam and the brake cam in the base circle segment;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a schematic structural view of an ignition push rod and a brake push rod of the first embodiment of the present invention;

FIG. 4 is a schematic structural view of a controller body according to a first embodiment of the present invention;

FIG. 5 is a schematic view of a control link structure according to a first embodiment of the present invention;

FIG. 6 is a schematic view of a middle tappet configuration according to a first embodiment of the present invention;

FIG. 7 is a schematic illustration of the first embodiment of the present invention in an engine braking operating condition;

FIG. 8 is a schematic illustration of the first embodiment of the present invention with the exhaust cam out of the base circle portion when switching from the ignition operating condition to the braking operating condition;

FIG. 9 is a schematic illustration of the first embodiment of the present invention with the brake cam out of the base circle portion when switching from the ignition operating condition to the braking operating condition;

FIG. 10 is a schematic illustration of the first embodiment of the present invention with the exhaust cam out of the base circle portion when switching from the braking operating condition to the ignition operating condition;

FIG. 11 is a schematic view of an alternate construction of the ignition push rod and the brake push rod and the intermediate tappet of the first embodiment of the present invention;

FIG. 12 is a schematic view of the construction of a second embodiment of the middle tappet of the present invention;

FIG. 13 is a schematic view of the second embodiment of the present invention in an ignition operating condition with both the exhaust cam and the brake cam in the base circle segment;

FIG. 14 is a schematic illustration of the second embodiment of the present invention with the brake cam out of the base circle portion when switching from the ignition operating condition to the braking operating condition;

FIG. 15 is another schematic view of a middle lifter according to a second embodiment of the present invention;

FIG. 16 is a schematic view of another embodiment of the control rod drive of the present invention;

FIG. 17 is another configuration of the controller body of the switchable push rod mechanism of the present invention;

FIG. 18 is a schematic view of the switchable pushrod mechanism of the present invention applied to both the exhaust and intake valve trains;

detailed description of the preferred embodiments

Fig. 1 to 11 illustrate a first embodiment of the present invention, in this embodiment, as shown in fig. 1 and 2, in addition to an exhaust cam 101 and an intake cam 103 for normal ignition of an engine for each cylinder, a brake cam 102 dedicated to braking of the engine is provided on the camshaft 1, the brake cam 102 has three lobes, two of the smaller lobes are symmetrically distributed and located near the top dead center in relation to the position of the crankshaft for opening the exhaust valve to release compressed gas each time the piston moves to the top dead center in the engine braking state, and the other larger lobe is located in the power stroke of the engine for opening the exhaust valve in the power stroke to allow exhaust gas to enter the cylinder again to realize compression release again to generate braking in the exhaust stroke,

lifters

201 and 202 are provided on the exhaust cam 101 and the brake cam 102, respectively. The switchable push rod mechanism comprises an ignition push rod 301, a brake push rod 302, a push rod spring 401, an upper spring seat 402, a lower spring seat 403, a controller body 6, a control pull rod 7, a return spring 8, a middle tappet 9, a guide pin 10, a plug 11 and an electromagnetic valve 12. The lower ends of the ignition push rod 301 and the brake push rod 302 are spherical, as shown in fig. 3, the upper ends are plate-shaped, the cross section of the top end of the plate-shaped is arc-shaped, two sides of the top of the plate-shaped is respectively provided with a guide groove 303, a push rod spring 401, an upper spring seat 402 and a lower spring seat 403 are arranged on the ignition push rod 301 and the brake push rod 302, the lower spring seat 403 is an open elastic snap spring, after the upper spring seat 402 and the push rod spring 401 are assembled, the lower spring seat 403 can be clamped on a step 304 on the push rod, the top of the upper spring seat 402 is spherical and is contacted with a baffle 603, when the push rod swings left and right, the push rod spring and the spring seat can swing together with the push rod, so that the push rod is always subjected to spring force, and the push rod is kept in contact with a transmission system between a tappet and a cam. As shown in fig. 4, a controller body 6 is installed on the engine, a plunger hole 601, a tappet hole 602 and a baffle 603 are installed on the controller body 6, the plunger hole 601 is connected with a lubricating oil passage with a certain pressure of the engine, and an electromagnetic valve 12 is installed on the oil passage to control the connection and the disconnection of the lubricating oil. The controller body 6 is provided with a control pull rod 7, a return spring 8, a middle tappet 9, a guide pin 10 and a plug 11, one end of the control pull rod 7 is a plunger, as shown in fig. 5, the control pull rod 7 is installed in a plunger hole 601 of the controller body 6, the other end of the control pull rod is a cylinder, the control pull rod 7 is installed in a guide hole coaxial with the plunger hole 601 on the controller body 6 and provides a supporting and guiding function for the control pull rod 7, the middle part of the control pull rod 7 is plate-shaped, two waist-shaped holes are arranged in the middle, a pull rod pin 701 is respectively installed on two sides of the two waist-shaped holes, the pull rod pin 701 protrudes into the waist-shaped holes, the ignition push rod 301 and the brake push rod 302 respectively penetrate through the two waist-shaped holes of the control pull rod 7, the protruding parts of the pull rod pins 701 on two sides of the waist-shaped holes are clamped in the guide groove 303 on the top of the push rod, so that the control pull rod 7 can push the ignition push rod 301 and the brake push rod 302 to swing left and right through the pull rod 701, while providing guidance for the ignition push rod 301 and the brake push rod 302, allowing them to move up and down while limiting their rotation. The return spring 8 is compressed and then installed on a cylinder at one end of the control pull rod 7, one end of the return spring is pressed on the controller body 6, a certain acting force is generated on the control pull rod 7, and the acting force is smaller than that of lubricating oil with certain pressure of an engine on the control pull rod 7. A middle tappet 9 is installed in a tappet hole 602 of the controller body 6, as shown in fig. 6, the upper portion of the middle tappet 9 is a cylinder, a guide groove 902 is formed in the cylinder, a ball socket is formed at the top end, a rectangular lower end is formed at the lower end, grooves 901 with circular arc-shaped cross sections are respectively formed in two sides of the cylinder, and a partition plate 903 is arranged in the middle of the cylinder and used for limiting the position of the push rod in horizontal swing. The guide pin 10 is mounted on the controller body 6, and its top end is deep into the guide groove 901 of the middle tappet 9, for allowing the middle tappet 9 to slide up and down while not allowing it to rotate. A rocker push rod 13 and a rocker mechanism 14 are arranged above the controller body 6, one end of the rocker push rod 13 is spherical, the other end of the rocker push rod 13 is a ball socket, the ball socket is respectively connected with the middle tappet 9 and the rocker mechanism 14, and the rocker mechanism 14 can be driven to open and close the exhaust valve through the driving of the middle tappet 9.

In the first embodiment of the present invention, when the engine is operated in the ignition state, as shown in fig. 1 and fig. 2, when the electromagnetic valve 12 is in the power-off state, the lubricant passage is disconnected, the control rod 7 is not subjected to the force of the lubricant, under the action of the return spring 8, the control rod 7 pushes the ignition push rod 301 and the brake push rod 302 to one side of the brake push rod 302, at this time, the top end of the ignition push rod 301 contacts with the circular arc groove 901 on one side of the lower end of the middle tappet 9, while the brake push rod 302 is outside the circular arc groove 901 on the other side of the lower end of the middle tappet and cannot contact with the middle tappet 9, at this time, the ignition push rod 301 pushes the middle tappet 9 according to the lift of the exhaust cam 101, the middle tappet 9 further pushes the rocker push rod 13 and the rocker mechanism 14 to open and close the exhaust valve according to the valve timing and lift in the ignition state, while the brake push rod 302 cannot contact with the middle tappet 9, in an empty reciprocating state by the brake cam 102.

When the engine needs to be switched to the engine braking operation state, the electromagnetic valve 12 is energized, engine lubricating oil with a certain pressure enters the plunger hole 601 to generate acting force on the control pull rod 7, and overcomes the acting force of the return spring 8 to push the ignition push rod 301 and the brake push rod 302 to swing to one side of the ignition push rod 301, at this time, if the exhaust cam 101 and the brake cam 102 are both in the base circle part, neither the ignition push rod 301 nor the brake push rod 302 has lift, and are in the lowest position, and the top end arc part thereof has a certain gap with the arc grooves 901 on both sides of the middle tappet 9 to allow the push rods to swing left and right, at this time, the control pull rod 7 can smoothly push the ignition push rod 301 and the brake push rod 302 to swing to one side of the ignition push rod 301, so that the top end of the brake push rod 302 contacts with the arc groove 901 on one side of the lower end of the middle tappet 9, and the ignition push rod 301 is separated from the middle tappet 9, as shown in fig. 7. At this time, the brake push rod 302 pushes the middle tappet 9 according to the lift of the brake cam 102, the middle tappet 9 further pushes the rocker push rod 13 and the rocker mechanism 14 to open and close the exhaust valve according to the valve timing and lift in the braking state, so that the engine enters the braking working state, and the ignition push rod 301 is in the empty reciprocating state under the action of the exhaust cam 101 because of being unable to contact with the middle tappet 9. When the engine needs to exit from the braking operation state, the electromagnetic valve 12 is powered off, so that the lubricating oil in the plunger hole 601 is drained, the control pull rod 7 pushes the ignition push rod 301 and the brake push rod 302 to one side of the brake push rod 302 under the action of the return spring 8, the top end of the ignition push rod 301 is in contact with the arc groove 901 at one side of the lower end of the middle tappet 9, the brake push rod 302 is separated from the middle tappet 9, the engine returns to the ignition operation state shown in fig. 1, and the brake push rod 302 returns to the empty reciprocating state.

In the first embodiment of the present invention, as described above, when the exhaust cam 101 and the brake cam 102 are both in the base circle portion, the control rod 7 can smoothly push the ignition push rod 301 and the brake push rod 302 to swing left and right to switch the engine between the ignition operation state and the brake operation state, and when the exhaust cam 101 or the brake cam 102 is not in the base circle portion (at this time, the ignition push rod or the brake push rod has a certain lift), how to avoid the problem that the ignition push rod 301 and the brake push rod 302 interfere with the intermediate tappet 9 to cause the switching failure when the engine is switched in the operation state, or when one of the push rods is not in the base circle portion to cause the valve train to generate impact damage during the switching is a key problem to be solved by the present invention. The design scheme of the embodiment can avoid the problems, and the principle and the process are as follows: in this embodiment, when the engine is switched from the ignition operation state to the engine braking operation state, if the exhaust cam 101 is not located at the base circle portion at this time, the exhaust cam 101 pushes the ignition push rod 301 and the middle tappet 9 to generate a certain lift, as shown in fig. 8, due to the action of the valve spring force (which is a large valve spring force in the case of a medium-heavy diesel engine), a large force exists between the ignition push rod 301 and the middle tappet 9, and due to the action of the arc groove 901 at the lower end of the middle tappet 9, the driving force generated by the lubricating oil on the control pull rod 7 cannot push the ignition push rod 301 to withdraw from the contact state with the middle tappet 9, the brake push rod 302 cannot come into contact with the middle tappet 9, and until the exhaust cam 101 rotates to the base circle portion, the force between the ignition push rod 301 and the middle tappet 9 disappears, at this time, the control rod 7 has a condition of pushing the ignition push rod 301 to withdraw from contact with the middle tappet 9 under the action of the pressure of the lubricating oil, and if the brake cam 102 is also at the base circle part, the lubricating oil can drive the control rod 7 to smoothly push the ignition push rod 301 to withdraw from contact with the middle tappet 9 and enable the brake push rod 302 to enter a contact state with the middle tappet 9, so that the switching from the ignition working state to the engine braking working state of the engine is realized. If the exhaust cam 101 is located at the base circle portion and the brake cam 102 is not located at the base circle portion, as shown in fig. 9, at this time, the brake push rod 302 has a certain lift, the top portion thereof is located at a position higher than the arc groove 901 of the middle tappet, when the control lever 7 pushes the brake push rod 302 to swing to the side of the ignition push rod 301 under the action of the lubricating oil pressure, the top portion of the brake push rod 302 will contact with the side surface of the lower end of the middle tappet 9, and the power train between the brake push rod 302 and the brake cam 102 is always kept in contact due to the action of the push rod spring 401, the brake push rod 302 will slide upwards or downwards along with the lift of the brake cam 102 along with the side surface of the lower end of the middle tappet 9, only when the brake cam 102 rotates to the base circle portion, the top portion of the brake push rod 302 will drop to a position lower than the arc groove 901 of the lower end of the middle tappet 9, at this time, the control lever 7 can push the brake push rod 302 to contact with the middle tappet 9, meanwhile, the ignition push rod 301 is withdrawn from contact with the middle tappet 9, so that the engine is switched from the ignition working state to the engine braking working state. When the engine needs to exit from the braking operation state, the electromagnetic valve 12 is powered off, the lubricating oil in the plunger hole 601 is drained, according to the same operation principle and process as the operation principle and process when the engine needs to switch from the ignition operation state to the braking operation state, if the brake cam 102 is not in the base circle part, because a large acting force exists between the brake push rod 302 and the middle tappet 9, the acting force of the return spring 8 cannot push the control pull rod 7 to cause the brake push rod 302 to exit from the contact with the middle tappet 9, if the exhaust cam 101 is not in the base circle part, as shown in fig. 10, the ignition push rod 301 has a certain lift, the top of the ignition push rod 301 is higher than the position of the arc groove 901 of the middle tappet 9, the control pull rod 7 pushes the ignition push rod 301 to cause the top to abut against the side surface of the lower end of the middle tappet 9 and to slide upwards or downwards along with the lift of the exhaust cam 101 under the action of the return spring 8, when the exhaust cam 101 rotates to the base circle part, the top of the ignition push rod 301 descends to a position lower than the arc groove 901 at the lower end of the middle tappet 9, at this time, the control pull rod 7 can push the ignition push rod 301 to enable the ignition push rod 301 to enter a contact state with the middle tappet 9, and simultaneously, the brake push rod 302 is enabled to exit the contact state with the middle tappet 9, so that the switching from the brake working state to the engine ignition working state of the engine is realized. Therefore, according to the principle and process described above, in the present invention, in the switching process of the contact and the contact withdrawal of the ignition push rod 301 and the brake push rod 302 with the intermediate tappet 9, the control rod 7 can only switch the contact and the contact withdrawal of the ignition push rod 301 and the brake push rod 302 with the intermediate tappet 9 when the exhaust cam 101 and the brake cam 102 are simultaneously in the base circle portion, so that the problem of impact damage caused by incapability of switching or incapability of switching in the base circle portion is avoided, and the reliability of the operation of the present invention is ensured.

Fig. 11 illustrates another structure of the ignition push rod 301 and the brake push rod 302 and the middle tappet 9 according to the first embodiment of the present invention, wherein the top ends of the ignition push rod 301 and the brake push rod 302 are spherical, and a ball socket 93 is respectively disposed on both sides of the lower end of the middle tappet 9, which is advantageous in that no guide groove is required to be disposed on the ignition push rod 301 and the brake push rod 302, the rotation of the push rods themselves is allowed, and the pull rod pin 701 can be eliminated on the control pull rod 7, thereby simplifying the structure and the process.

Fig. 12 to 15 illustrate two embodiments of the present invention, which are different from the first embodiment, in the present embodiment, as shown in fig. 13, the controller body 61 of the switchable push rod mechanism is provided with two

middle tappets

91 and 92, the lower ends of the two middle tappets are provided with bulbs 910, as shown in fig. 12, and are provided with flanges 911, and a tappet spring 411 is respectively arranged between the flanges 911 at the lower ends of the two middle tappets and the controller body 61, so that the transmission system between the middle tappets and the cams is always kept in contact. The lower end ball heads of the

middle tappets

91 and 92 are respectively connected with an ignition push rod 311 and a brake push rod 312, the lower ends of the ignition push rod 311 and the brake push rod 312 are spherical, the upper ends of the ignition push rod 311 and the brake push rod 312 are ball sockets, the ignition push rod 311 and the brake push rod are respectively connected with the tappets and the middle tappets, and the ignition push rod 311 and the brake push rod 312 are respectively driven by an exhaust cam 101 and a brake cam 102. The upper ends of the

middle tappets

91 and 92 are provided with ball sockets 913, as shown in fig. 12, one side of the ball sockets is provided with a protruded stopper 914 for limiting the swing position of the push rod when switching, the

middle tappets

91 and 92 are provided with guide grooves 912, the

middle tappets

91 and 92 are installed in the tappet holes of the controller body 61, the stoppers 911 at the ball sockets of the upper ends of the middle tappets are relatively close to the outside, and the controller body 61 outside the

middle tappets

91 and 92 is provided with guide pins 10 for preventing the rotation of the middle tappets. The controller body 61 is provided with a plunger hole, a control pull rod 71 is arranged in the plunger hole, two ends of the control pull rod 71 are cylinders, the middle of the control pull rod is plate-shaped, the middle of the control pull rod is provided with a hole, and one end of the control pull rod is provided with a return spring 8. The rocker push rod 131 passes through a hole in the middle of the control pull rod 71, one end of the rocker push rod is connected with the rocker mechanism, and the other end of the rocker push rod is switchably connected with the

middle tappet

91 or 92 under the control of the control pull rod 71. The plunger hole of the controller body 61 is connected with a lubricating oil passage with certain pressure of an engine, and an electromagnetic valve 12 is arranged on the oil passage to control the on and off of the lubricating oil passage.

In the second embodiment of the present invention, the operation principle and process are similar to those of the first embodiment, except that the control rod 71 is used for switching between the ignition operation state and the engine braking operation state by controlling the switching of the connection between the rocker push rod 131 and the

middle tappet

91 or 92. When the engine is in an ignition state, as shown in fig. 13, the electromagnetic valve 12 is in a power-off state, the lubricating oil passage is disconnected at this time, the control pull rod 71 is not acted by the lubricating oil, the control pull rod 71 pushes the rocker push rod 131 to one side of the middle tappet 91 under the action of the return spring 8, so that the rocker push rod 131 is in contact with the middle tappet 91, at this time, the middle tappet 91 pushes the rocker push rod 131 and the rocker mechanism 14 according to the lift of the exhaust cam 101, so that the exhaust valve is opened and closed according to the valve timing and lift in the ignition state, and the middle tappet 92 is in an idle reciprocating state under the action of the brake cam 102 because the middle tappet 92 cannot be in contact with the rocker push rod 131.

When the engine needs to be switched to the engine braking operation state, the electromagnetic valve 12 is energized, engine lubricating oil with a certain pressure enters the plunger hole to generate acting force on the control pull rod 71, and overcomes the acting force of the return spring 8 to push the rocker push rod 131 to swing to one side of the middle tappet 92, at this time, if the exhaust cam 101 and the brake cam 102 are both in the base circle part, the

middle tappets

91 and 92 have no lift and are in the lowest position, the top end part of the middle tappet has a gap with the rocker push rod 131, at this time, the control pull rod 71 can smoothly push the rocker push rod 131 to be switched to be in contact with the middle tappet 92, at this time, the middle tappet 92 pushes the rocker push rod 131 and the rocker mechanism 14 according to the lift of the brake cam 102, so that the exhaust valve is opened and closed according to the valve timing and lift of the engine braking state, and, in an empty reciprocating state by the exhaust cam 101. When the engine needs to exit from the braking working state, the electromagnetic valve 12 is powered off, so that lubricating oil in the plunger hole is drained, the control pull rod 71 pushes the rocker push rod 131 to be in contact with the middle tappet 91 under the action of the return spring 8, the engine returns to the ignition working state, and the middle tappet 92 returns to the empty reciprocating state.

In the second embodiment of the present invention, as described above, when the exhaust cam 101 and the brake cam 102 are both located at the base circle portion, the control rod 71 can control the rocker arm push rod 131 to smoothly switch the engine between the ignition operation state and the braking operation state, and when the exhaust cam 101 or the brake cam 102 is not located at the base circle portion, the design scheme of the embodiment can still ensure that the control rod 71 can switch the rocker arm push rod 131 to contact with the

middle tappet

91 or 92 only when the exhaust cam 101 and the brake cam 102 are both located at the base circle portion, so as to avoid the incapability of switching or the impact damage during the switching process, and the principle and the process thereof are similar to those of the first embodiment and can be understood with reference to the first embodiment. In this embodiment, when the engine is switched from the ignition operation state to the engine braking operation state, if the exhaust cam 101 is not located in the base circle portion, at this time, because a large force exists between the intermediate tappet 91 and the rocker arm push rod 131, the control rod 71 cannot push the rocker arm push rod 131 to move out of contact from the ball socket of the intermediate tappet 91, only when the exhaust cam 101 returns to the base circle, the control rod 71 can push the rocker arm push rod 131 to move out of contact, at this time, if the brake cam 102 is not located in the base circle portion, as shown in fig. 14, the intermediate tappet 92 has a certain lift, at this time, the upper end position of the intermediate tappet 92 is higher than the spherical position of the lower end of the rocker arm push rod 131, when the control rod 71 pushes the rocker arm push rod 131 to swing to the right, due to the blockage of the upper end side surface of the intermediate tappet 92, the rocker arm push rod 131, only when the brake cam 102 returns to the base circle position, at which time the upper end position of the intermediate tappet 92 drops below the spherical position of the lower end of the rocker push rod 131, the control link 71 can push the rocker push rod 131 into contact with the intermediate tappet 92 and simultaneously out of contact with the intermediate tappet 91. When the engine needs to exit the braking operation state, according to the same principle as that described above, when any one of the exhaust cam 101 and the brake cam 102 is not located at the base circle portion, the control rod 71 cannot switch the contact between the rocker arm push rod 131 and the

intermediate tappet

91 or 92, and therefore, the switching of the contact between the rocker arm push rod 131 and the

intermediate tappet

91 or 92 can be performed only when the exhaust cam 101 and the brake cam 102 are located at the base circle portion at the same time, thereby ensuring the reliability of the operation of the device.

Fig. 15 illustrates another structure of two

intermediate tappets

91 and 92 according to the second embodiment of the present invention, wherein the

intermediate tappets

91 and 92 are mushroom-shaped structures and are directly driven by an exhaust cam 101 and a brake cam 102, respectively, so that the lower ignition push rod and brake push rod and the tappets can be omitted, the structure is simpler, the cost is lower, and the operation principle and the process are the same as those of the second embodiment.

Fig. 16 illustrates another driving mode of the control rod 7 according to the present invention, which is characterized in that the control rod 7 is connected to a driving shaft of a solenoid valve 12 and is directly driven by the solenoid valve 12, and the driving force generated by the driving shaft of the solenoid valve 12 when the solenoid valve 12 is energized is greater than the acting force of the return spring 8, which is advantageous in that a lubricant passage does not need to be provided for a plunger hole of the controller body 6, and the operation of the control rod 7 is not affected by the pressure, temperature and quality of the lubricant.

Furthermore, a plunger hole on a controller body of the switchable push rod mechanism is connected with compressed air of a vehicle, an electromagnetic valve is arranged on a connecting pipeline, the control pull rod is driven by the compressed air of the vehicle, the response speed of the control pull rod can be improved, and the structure is simplified.

Fig. 17 illustrates another structure of the controller body of the switchable push rod mechanism of the present invention, in which the plunger hole portion is separately arranged from the tappet hole portion, the controller body is provided with only the plunger hole and is disposed at a proper position on the cylinder block or the cylinder head according to the structure of the engine, and the intermediate tappet is disposed at a proper position on the cylinder block or the cylinder head of the engine according to the structure of the engine, so that the arrangement of the device is more flexible.

Further, the switchable push rod mechanism of the present invention can be applied to both the exhaust valve train and the intake valve train, as shown in fig. 18, besides providing the exhaust cam 101 and the intake cam 103 for the normal ignition of the engine for each cylinder, the camshaft 1 is further provided with the exhaust brake cam 102 and the intake brake cam 104 specially used for the braking of the engine, the exhaust brake cam 102 has two small lobes and is distributed symmetrically, the position relationship with the crankshaft is that the exhaust brake cam is located near the top dead center for opening the exhaust valve to release compressed gas when the piston moves to the top dead center each time in the braking state of the engine, the intake brake cam 104 has two lobes and is located in the intake stroke and the power stroke of the engine for opening the intake valve to allow air to enter the cylinder when the piston moves downwards each time, the engine brake system has the advantages that when the engine is in a brake working state, high-temperature waste gas does not need to be sucked into the cylinder again for compression, air compressed by the piston each time is fresh air, and the working temperature of the engine during brake can be reduced.

Claims

1. The utility model provides a changeable push-rod engine brake, includes camshaft, tappet, changeable push-rod mechanism, rocking arm push rod and rocking arm mechanism, characterized by: the camshaft is characterized in that at least one cylinder is provided with an exhaust cam and an intake cam for the ignition work of an engine, and also provided with a brake cam for the braking work of the engine, the switchable push rod mechanism is provided with a controller body, an ignition push rod, a brake push rod, a control pull rod, a return spring, a middle tappet, a guide pin and an electromagnetic valve, the controller body is provided with a plunger hole and a tappet hole, the control pull rod is arranged in the plunger hole of the controller body, two ends of the control pull rod are cylinders, one end of the control pull rod is arranged in the plunger hole of the controller body, the other end of the control pull rod is provided with the return spring, the middle of the control pull rod is plate-shaped and provided with two holes, the ignition push rod and the brake push rod are respectively arranged in the two holes, the lower ends of the ignition push rod and the brake push rod are connected with, the device is characterized in that a middle tappet is arranged in a tappet hole of the controller body, the upper end of the middle tappet is connected with a rocker push rod, the lower end of the middle tappet is provided with an arc surface, the lower end of the middle tappet can be respectively connected with the upper ends of an ignition push rod or a brake push rod, a plunger hole of the controller body is connected with a lubricating oil passage with certain pressure of an engine, and an electromagnetic valve is arranged on the lubricating oil passage to control the on and off of the lubricating oil passage.

2. A switchable pushrod engine braking device according to claim 1, wherein: the braking cam is provided with three lobes, wherein two smaller lobes are symmetrically distributed, the two smaller lobes and the crankshaft are in a position relation that an exhaust valve is opened when a piston reaches the position near a top dead center every time, and the other larger lobe is positioned to open the exhaust valve in a power stroke of the engine.

3. A switchable pushrod engine braking device according to claim 1, wherein: the lower ends of the ignition push rod and the brake push rod are spherical, the upper ends of the ignition push rod and the brake push rod are plate-shaped, the cross section of the top of the plate-shaped top is arc-shaped, two sides of the top are respectively provided with a guide groove, the upper portion of the middle tappet is a cylinder, the guide groove is formed in the cylinder, a ball socket is formed in the top end of the cylinder, the lower end of the middle tappet is rectangular, two sides of the middle hole of the control pull rod are respectively provided with a pull rod pin, the pull rod pins protrude into the holes, and protruding portions of the two holes are clamped in the guide grooves in the two sides of the tops of the ignition push rod and the brake push rod.

4. A switchable pushrod engine braking device according to claim 1, wherein: the upper ends of the ignition push rod and the brake push rod are spherical, the lower end of the middle tappet is rectangular, ball sockets are arranged on two sides of the middle tappet respectively, and a partition plate is arranged in the middle of the middle tappet.

5. A switchable pushrod engine braking device according to claim 1, wherein: the switchable push rod mechanism is characterized in that two middle tappets are arranged on a controller body of the switchable push rod mechanism, the lower ends of the two middle tappets are respectively connected with an ignition push rod and a brake push rod, two ends of the ignition push rod and the brake push rod are respectively connected with the middle tappets and the tappets and are respectively driven by an exhaust cam and a brake cam, a control pull rod is arranged in a plunger hole in the controller body, two ends of the control pull rod are cylinders, the middle of the control pull rod is plate-shaped, a hole is formed in the middle of the control pull rod, a return spring is arranged at one end of the control pull rod, the rocker push rod penetrates through the hole in the middle of the control pull rod, one end of the rocker push rod is connected with the rocker mechanism, and the other end of the rocker push rod is switchably connected with one of the two middle tappets under the control of the control pull rod.

6. The switchable pushrod engine braking device of claim 5, wherein: the lower end of the middle tappet is provided with a ball head and a flange, a tappet spring is arranged between the flange at the lower end of the middle tappet and the controller body, the upper end of the middle tappet is provided with a ball socket, one side of the ball socket is provided with a protruding baffle, and the middle tappet is provided with a guide groove.

7. The switchable pushrod engine braking device of claim 5, wherein: the two middle tappets are of mushroom-shaped structures and are directly driven by the exhaust cam and the brake cam respectively.

8. A switchable pushrod engine braking device according to claim 1 or 5, wherein: the plunger hole on the controller body of the switchable push rod mechanism is connected with compressed air of a vehicle, the connecting pipeline is provided with an electromagnetic valve, and the control pull rod is driven by the compressed air of the vehicle.

9. A switchable pushrod engine braking device according to claim 1 or 5, wherein: the control pull rod is connected with a driving shaft of the electromagnetic valve and is directly driven by the electromagnetic valve.

10. A switchable pushrod engine braking device according to claim 1 or 5, wherein: the plunger hole part and the tappet hole part of the controller body of the switchable push rod mechanism are separately arranged, and the controller body is arranged on the cylinder body or the cylinder cover.

11. A switchable pushrod engine braking device according to claim 1 or 5, wherein: the exhaust braking cam and the intake braking cam are arranged on a camshaft of the engine, the exhaust braking cam and the intake braking cam are specially used for engine braking, the exhaust braking cam is provided with two small peach-shaped points and is symmetrically distributed, the position relation of the exhaust braking cam and a crankshaft is that the exhaust braking cam is positioned near a top dead center when a piston reaches the top dead center every time, and the intake braking cam is provided with two peach-shaped points and is positioned at an intake stroke and a power stroke of the engine to open an intake valve.