CN211448786U

CN211448786U - Compression release in-cylinder brake system for engine

Info

Publication number: CN211448786U
Application number: CN201922448486.6U
Authority: CN
Inventors: 王立峰; 王秀强; 吴龙龙; 王孟晓; 王昊天; 吴贝贝; 从田增; 吴鹏超; 苏明涛; 衣金水
Original assignee: Weifang Lichuang Electronic Technology Co Ltd
Current assignee: Weifang Lichuang Electronic Technology Co Ltd
Priority date: 2019-12-28
Filing date: 2019-12-28
Publication date: 2020-09-08
Anticipated expiration: 2029-12-28

Abstract

The utility model discloses a compression release type engine in-cylinder brake system, which comprises a gas distribution mechanism, an oil cylinder device, an oil pumping device and an oil supply device, wherein all cylinders share one oil supply device; each cylinder is respectively provided with an oil cylinder device and an oil pumping device which are communicated through a pressure transmission oil path, and the pressure transmission oil path is communicated with an oil supply device through a one-way valve; when the brake is carried out in the cylinder, the electromagnetic directional valve is electrified, engine oil with the pressure of P1 is provided for the pressure transmission oil path, the cam abuts against and pushes the oil pumping device, high-pressure oil is pumped to the oil cylinder device to push the rocker arm to open the valve, and the brake in the cylinder is realized; when the brake is not carried out in the cylinder, the electromagnetic directional valve is powered off, the engine oil with the pressure of P2 is supplied to the pressure transmission oil path, the pressure of P1 is more than P2, the oil cylinder device and the oil pumping device return, and the cam is separated from the oil pumping device. The compression release type engine in-cylinder brake system of the utility model has stable and reliable work and low failure rate; and the structure is simple, the limit of the number of the engine cylinders is avoided, and the application is wide.

Description

Compression release in-cylinder brake system for engine

Technical Field

The utility model relates to an engine variable valve technical field especially relates to a braking system in compression release formula engine cylinder.

Background

In the normal operation process of the engine, the engine completes four working cycles of air intake, compression, work application and exhaust every time the camshaft rotates 360 degrees. At the end of the compression stroke, fuel is combusted in the cylinder, and work is applied in the subsequent expansion stroke.

The brake in the engine cylinder is a form of auxiliary brake of the whole vehicle, and the brake in the engine cylinder contributes to improving the brake capacity of the whole vehicle and reducing the brake load of the main brake of the whole vehicle. When the engine cylinder is braked, the compression stroke engine applies auxiliary work to the outside, when the compression stroke is close to the top dead center, the exhaust valve is opened by a small lift range under the driving of the braking device in the engine cylinder, the compressed high-pressure gas in the cylinder is rapidly released, the pressure in the cylinder is rapidly reduced, and the energy of the power stroke is reduced, so that the engine does not apply work to the outside basically in the next power stroke, the engine is decelerated, and the purpose of braking in the engine cylinder is achieved.

Chinese utility model patent with publication number CN201241740Y, entitled "a four-stroke internal combustion engine rocker arm integrated form arresting gear" discloses an engine in-cylinder arresting gear, it sets up two braking archs on the exhaust cam for realize opening the intake valve before the intake stroke finishes and increasing the air input, open exhaust valve release pressure before the compression stroke finishes and realize the in-cylinder braking of engine, in order to offset the valve lift that the braking arch arouses when the engine normally operates, need set up hydraulic control's clearance compensation mechanism on the rocker 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.

To this end, the applicant developed a new engine in-cylinder brake device and filed a patent application with publication number CN110566309A entitled "compression-release engine in-cylinder brake device", but in subsequent practical applications, the applicant found that the following problems existed, which are to be further improved: the structure is too complex, and the engine can only be applied to a multi-cylinder engine with an even number of engine cylinders, and each cylinder of the engine is required to have a cylinder with a 360-degree crank angle phase corresponding to the cylinder, so that the application is limited.

Disclosure of Invention

In view of this, the technical problem to be solved by the present invention is: the compression release type engine in-cylinder brake system is high in working reliability and low in failure rate; and the structure is simple, the application performance is good, and the engine cylinder number is not limited.

In order to solve the technical problem, the technical scheme of the utility model is that: compression release formula engine in-cylinder braking system applies to the valve train of engine, includes: the engine comprises an oil cylinder device, an oil pumping device and an oil supply device, wherein all cylinders of the engine share one oil supply device;

the valve actuating mechanism comprises a camshaft, a rocker arm and a valve, and the camshaft is provided with a cam;

the oil supply device comprises an electromagnetic directional valve, an oil supply path, a pressure reducing path and a pressure reducing path, wherein an overflow pressure retaining valve is arranged in the pressure reducing path, a pressure reducing valve is arranged in the pressure reducing path, and the engine oil pressure of the engine before pressure reduction is defined as P1 and the engine oil pressure of the engine after pressure reduction is defined as P2;

each cylinder is provided with the oil cylinder device and the oil pumping device respectively, the oil cylinder device is communicated with the oil pumping device through a pressure transmission oil way, and the pressure transmission oil way is communicated with the oil supply oil way through a one-way valve;

when the brake is carried out in the cylinder, the electromagnetic directional valve is electrified, and the oil supply oil circuit supplies the engine oil with the pressure of P1 to the pressure transmission oil circuit; the cam abuts against and pushes the oil pumping device, the oil pressure in the oil pumping device rises, the oil pumping device pumps high-pressure oil to the oil cylinder device through the pressure transmission oil path, and the oil cylinder device pushes the rocker arm to open the valve;

when the brake is not in the cylinder, the electromagnetic directional valve is powered off, and the oil supply oil circuit supplies the engine oil with the pressure of P2 to the pressure transmission oil circuit; the oil cylinder device and the oil pumping device return respectively, and the cam is separated from the oil pumping device.

Wherein, the oil pumping device includes:

the bottom of the plunger sleeve is closed, the top of the plunger sleeve is open, a plunger sleeve oil inlet and outlet hole is formed in the sleeve wall of the plunger sleeve and connected with the pressure transmission oil path;

the plunger is arranged in the inner cavity of the plunger sleeve in a sliding mode, a plunger sleeve oil cavity is formed between the bottom of the plunger and the bottom of the plunger sleeve, the plunger sleeve oil inlet and outlet hole is communicated with the plunger sleeve oil cavity, the top of the plunger extends out of an opening of the plunger sleeve, the top of the plunger is in contact with the cam when braking in a cylinder, and the top of the plunger is not in contact with the cam when braking in the cylinder;

and the plunger tension spring is positioned in the plunger sleeve oil cavity and connected between the bottom of the plunger sleeve and the bottom of the plunger.

The oil-saving brake device comprises a plunger sleeve, a plunger sleeve oil cavity, a plunger sleeve oil buffer hole, a plunger sleeve oil pressure retaining valve and a plunger sleeve oil cavity, wherein the sleeve wall of the plunger sleeve is also provided with the plunger sleeve oil buffer hole, the plunger sleeve oil buffer hole is communicated with an oil pan of an engine through the overflow pressure retaining valve, and the plunger sleeve oil buffer hole and; when the brake is not carried out in the cylinder, the plunger piston plugs the plunger sleeve buffer oil hole under the action of the plunger piston tension spring.

The plunger limiting device is arranged at the open end of the plunger sleeve; the plunger comprises a plunger large-diameter section and a plunger small-diameter section, the plunger large-diameter section is located in an inner cavity of the plunger sleeve, the plunger small-diameter section is connected with the plunger large-diameter section, a plunger step is formed at the transition position of the plunger large-diameter section and the plunger small-diameter section, and the plunger limiting device limits the plunger step during braking in the cylinder.

The plunger further comprises a plunger abutting section which is positioned outside the plunger sleeve and connected with the plunger small-diameter section, the radial dimension of the plunger abutting section is larger than that of the plunger small-diameter section, and the top surface of the plunger abutting section abuts against the cam when the cylinder brakes; when the brake is not performed in the cylinder, the top surface of the plunger abutting section is separated from the cam, and the plunger limiting device limits the plunger abutting section.

Wherein, the top surface of the plunger abutting section is a plane or an arc surface.

Wherein, oil cylinder device includes:

the top of the cylinder body is closed, the bottom of the cylinder body is open, a cylinder body oil inlet and outlet hole is formed in the cylinder wall of the cylinder body, and the cylinder body oil inlet and outlet hole is connected with the pressure transmission oil way;

the piston is arranged in an inner cavity of the cylinder body in a sliding mode, a cylinder body oil cavity is formed between the top of the piston and the top of the cylinder body, the cylinder body oil inlet and outlet hole is communicated with the cylinder body oil cavity, a piston rod is arranged at the bottom of the piston and extends out of an opening of the cylinder body, the bottom of the piston rod is in contact with the rocker arm and presses the rocker arm downwards to open the valve when braking is performed in the cylinder, and the bottom of the piston rod is not in contact with the rocker arm when braking is performed in the cylinder;

and the piston tension spring is positioned in the cylinder body oil cavity and connected between the top of the cylinder body and the top of the piston.

The piston is arranged on the cylinder wall of the cylinder body, the cylinder body oil drainage hole is communicated with an oil pan of an engine, the piston moves downwards during braking in the cylinder, and the cylinder body oil drainage hole is not communicated with an oil cavity of the cylinder body during operation of the oil pumping device; when the cam jacks up the valve through the valve actuating mechanism and the oil pumping device does not work, the oil drainage hole of the cylinder body is communicated with the oil cavity of the cylinder body; when the brake is not carried out in the cylinder, the piston blocks the oil drainage hole of the cylinder body under the action of the piston tension spring.

Wherein, the open end of the cylinder body is provided with a piston limiting device; a piston step is formed at the transition position of the piston and the piston rod, when the oil pumping device is braked in the cylinder to work, the piston limiting device does not limit the piston step, the distance between the piston step and the piston limiting device is S, and S is larger than 0;

when the cam jacks the valve through the valve actuating mechanism and the oil pumping device does not work, the piston limiting device limits the piston step, and S is 0.

The pressure transmission oil path is also connected with a low-pressure relief oil path, the low-pressure relief oil path is provided with a low-pressure relief valve and an overflow pressure retaining valve, the low-pressure relief valve is connected with the pressure transmission oil path, and the overflow pressure retaining valve is connected with an oil pan of the engine; the pressure relief pressure of the low-pressure relief valve is not higher than P1, and the pressure relief pressure of the low-pressure relief valve is higher than P2.

Wherein, the low pressure relief valve includes:

the valve body is provided with a valve body oil inlet and a valve body oil outlet which are communicated with a valve cavity of the valve body, the valve body oil inlet is connected with the pressure transmission oil path, and the valve body oil outlet is connected with the overflow pressure retaining valve;

a valve ball disposed within the valve cavity;

the compression spring is arranged in the valve cavity and clamped between the valve ball and the valve body oil outlet;

the limiting pin is arranged on the valve body and is positioned between the valve body oil inlet and the valve ball.

Wherein the cam is an exhaust cam; alternatively, the cam is an intake cam; alternatively, the cam is a single cylinder brake cam.

The cam can also be a total brake cam, the oil pumping devices are arranged around the total brake cam, and the number of the oil pumping devices is the same as that of cylinders of the engine.

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

After the technical scheme is adopted, the beneficial effects of the utility model are as follows:

because the compression release type engine in-cylinder brake system comprises the oil cylinder device, the oil pumping device and the oil supply device which are applied to the air distribution mechanism of the engine, all cylinders of the engine share one oil supply device; the oil supply device comprises an electromagnetic directional valve, an oil supply oil path, a pressure reducing oil path and a pressure relief oil path, the engine oil pressure of the engine before pressure reduction is P1, and the engine oil pressure of the engine after pressure reduction is P2; each cylinder of the engine is respectively provided with an oil cylinder device and an oil pumping device, the oil cylinder device is communicated with the oil pumping device through a pressure transmission oil way, and the pressure transmission oil way is communicated with an oil supply oil way through a one-way valve; when braking in the cylinder, the electromagnetic directional valve is electrified, engine oil with the pressure of P1 is provided for the pressure transmission oil path through the oil supply oil path, the cam abuts against and pushes the oil pumping device, the pressure of the engine oil in the oil pumping device is increased, the oil pumping device pumps high-pressure oil to the oil cylinder device through the pressure transmission oil path, and the oil cylinder device pushes the rocker arm to open the valve, so that braking in the cylinder is realized; when the brake is not carried out in the cylinder, the electromagnetic directional valve is powered off, the oil with the pressure of P2 is supplied to the pressure transmission oil path through the oil supply oil path, the oil cylinder device and the oil pumping device respectively return, the cam is separated from the oil pumping device, and the engine is in a normal running state. Because each cylinder of the engine is respectively provided with the oil cylinder device and the oil pumping device which are connected through the pressure transmission oil way, the pressure transmission oil way is communicated with the oil supply oil way of the oil supply device through the one-way valve, the brake/non-brake switching of all cylinders of the whole engine can be realized only by controlling the on/off of one electromagnetic directional valve, the requirement on a control circuit is low, the work is stable and reliable, and the failure rate is low; and the structure is simple, the arrangement is flexible and convenient, the engine cylinder number is not limited, the number of the cylinders is even or odd, the application performance is good, and the application is wider.

Drawings

Fig. 1 is a schematic view of an in-cylinder braking state of a compression-release engine in-cylinder braking system according to a first embodiment of the present invention;

FIG. 2 is a state diagram of the exhaust stroke of FIG. 1 after in-cylinder braking is completed;

fig. 3 is a schematic diagram of an embodiment of the present invention when the engine is in a normal operating state;

FIG. 4 is a hydraulic schematic of the oil supply of FIG. 1;

FIG. 5 is a schematic diagram of the oil pumping device of FIG. 1;

FIG. 6 is a schematic view of a construction of the cylinder apparatus of FIG. 1;

FIG. 7 is a schematic view showing another construction of the cylinder device of FIG. 1;

FIG. 8 is a schematic illustration of the closed state of the low pressure relief valve of FIG. 1;

FIG. 9 is a schematic diagram of the low pressure relief valve of FIG. 1 in an open state;

fig. 10 is a schematic view of a compression-release engine in-cylinder brake system according to a second embodiment of the present invention;

in the figure: i-a valve train; II, an oil pumping device; III-a cylinder device; IV-an oil supply unit;

10-valve; 11-valve spring; 12-a rocker arm; 13-a rocker shaft; 14-a push rod; 15-a tappet; 16-a cam; 16 a-total brake cam;

21-plunger sleeve; 211-the plunger is sleeved in the oil inlet and outlet; 212-plunger sleeve buffer oil hole; 213-plunger stop means; 22-a plunger; 221-a plunger abutting section; 2211-the plunger abuts the top surface of the segment; 23-plunger tension spring;

31-cylinder body; 311-cylinder block oil inlet and outlet holes; 312-cylinder block oil drain hole; 313-a piston stop; 32-a piston; 321-a piston rod; 33-piston tension spring;

40-a one-way valve; 60-an oil pan; 70-a pressure relief valve; 80-a solenoid directional valve; 100-an overflow pressure retaining valve; 200-an overflow pressure retaining valve; 300-an overflow pressure retaining valve;

90-low pressure relief valve; 91-a valve body; 92-a valve ball; 93-a compression spring; 94-a limit pin;

L0-Engine oil circuit; la-oil supply circuit; lb-pressure reducing oil path; lc-pressure relief oil path; an L-pressure transfer oil path; L1-Cylinder oil Circuit; l2-two cylinder oil circuit; l3-three cylinder oil circuit; l4-four cylinder oil circuit; l5-five cylinder oil circuit; l6-six cylinder oil circuit; a-a plunger sleeve oil cavity; b-cylinder body oil cavity.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and examples.

It should be noted that, in the present specification, terms of "upper", "lower", "top", "bottom", etc. indicating positions are defined for convenience of description based on the drawings; the terms "mounted," "connected," and the like are to be construed broadly and may, for example, be mechanical or electrical connections between elements; the elements may be directly connected or indirectly connected through an intermediate, and a person skilled in the art can understand the specific meaning of the above terms according to specific situations.

Example one

As shown in fig. 1, the first compression release type engine in-cylinder brake system of the present invention is applied to a valve train I of an engine, and includes: an oil pumping device II, an oil cylinder device III and an oil supply device IV.

When the tappet 15 and the push rod 14 push the rocker arm 12 from one side to swing around the rocker arm shaft 13 under the action of a cam 16 on a cam shaft, the other side of the rocker arm 12 presses the valve 10, and the valve is opened; when the camshaft rotates by a specified angle, the valve 10 returns under the action of the valve spring 11, and the valve is closed. The above is the process for controlling the valve action in the valve actuating mechanism I when the engine is in normal operation.

As shown in fig. 4, the oil supply device IV includes an oil supply passage La, a pressure reducing passage Lb, a pressure reducing passage Lc, and an electromagnetic directional valve 80. Wherein, the electromagnetic directional valve 80 preferably adopts a two-position three-way electromagnetic directional valve. An overflow pressure retaining valve 100 is provided in the pressure relief oil passage Lc, and a pressure reducing valve 70 is provided in the pressure reducing oil passage Lb, and for convenience of description, the oil pressure of the engine oil passage L0 before pressure reduction is defined as P1, the oil pressure of the engine after pressure reduction is defined as P2, and the set pressure of the overflow pressure retaining valve 100 is P2 or slightly higher than P2.

As shown in fig. 1, a case of a six-cylinder engine is illustrated, in which each cylinder is provided with an oil pumping device II and an oil cylinder device III, respectively, the oil cylinder device III and the oil pumping device II communicate through a pressure-transmitting oil passage L, which communicates through a check valve 40 with an oil supply oil passage La of a common one of the oil supply devices IV. Specifically, the method comprises the following steps: the first cylinder is communicated with the oil supply channel La through a first cylinder oil channel L1, the second cylinder is communicated with a second cylinder oil channel L2, the third cylinder is communicated with a third cylinder oil channel L3, the fourth cylinder is communicated with a fourth cylinder oil channel L4, the fifth cylinder is communicated with a fifth cylinder oil channel L5, the sixth cylinder is communicated with a sixth cylinder oil channel L6 and a check valve in each oil channel.

As shown in fig. 1, the oil pumping device II is installed at a proper position of the cam 16, and the position is designed to ensure that the cam 16 acts on the oil pumping device II, and the oil pumping device II pumps oil and pushes the piston 32 in the oil cylinder device III to move to open the valve 10 to realize exhaust braking, which is the moment just near the compression top dead center. As shown in fig. 5, the oil pumping device II includes: plunger sleeve 21, plunger 22, plunger extension spring 23. The bottom of the plunger sleeve 21 is closed, the top of the plunger sleeve 21 is open, a plunger sleeve oil inlet and outlet hole 211 is formed in the sleeve wall of the plunger sleeve 21, and the plunger sleeve oil inlet and outlet hole 211 is connected with the pressure transmission oil path L; further, a plunger sleeve buffer oil hole 212 is further provided on the sleeve wall of the plunger sleeve 21, as shown in fig. 1, the plunger sleeve buffer oil hole 212 communicates with the oil pan 60 of the engine through an overflow pressure-maintaining valve 300, and the pressure relief pressure of the overflow pressure-maintaining valve 300 is set to be equal to or slightly higher than the engine oil pressure P1; the open end of plunger sleeve 21 is further provided with a plunger stop 213 for limiting the active position of plunger 22. The plunger 22 is slidably disposed in an inner cavity of the plunger sleeve 21, a plunger sleeve oil cavity a is formed between the bottom of the plunger 22 and the bottom of the plunger sleeve 21, the plunger sleeve oil inlet and outlet hole 211 is communicated with the plunger sleeve oil cavity a, the top of the plunger 22 extends out of an opening of the plunger sleeve 21, the plunger 22 comprises a plunger large-diameter section located in the inner cavity of the plunger sleeve 21 and a plunger small-diameter section connected with the plunger large-diameter section, a plunger step is formed at a transition position of the plunger large-diameter section and the plunger small-diameter section, the plunger 22 further comprises a plunger abutting section 221 located outside the plunger sleeve 21 and connected with the plunger small-diameter section, the radial dimension of the plunger abutting section 221 is larger than that of the plunger small-diameter section, and a top surface 2211 of the plunger abutting section can be a plane or an arc surface matched with a cam surface of the cam 16 so as to have a larger contact area with the cam 16. The plunger tension spring 23 is located in the plunger sleeve oil chamber a and connected between the bottom of the plunger sleeve 21 and the bottom of the plunger 22, and the pulling force of the plunger tension spring 23 is far less than the pushing force of the oil pressure P1 to the plunger 22 but far greater than the pushing force of the oil pressure P2 to the plunger 22.

The plunger stopper 213 may be a closed ring, an unclosed ring, or a bar, and the shape thereof is not limited herein.

As shown in fig. 1, when the cylinder is braked, the plunger stopper 213 stops the plunger step. As shown in fig. 3, the plunger stopper 213 stops the plunger abutting section 221 when the cylinder is not actuated.

Wherein, the plunger stopper 213 is fixed at the open end of the plunger sleeve 21, which is an optimized design of the plunger sleeve 21. Obviously, the open end of plunger sleeve 21 may not be provided with plunger stop 213, in which case the stop function may be achieved by the base circle of cam 16 abutting against top surface 2211 of the plunger abutting section.

As shown in fig. 1, the cylinder device III is mounted on top of a rocker arm 12 (or other valve train). As shown in fig. 6, the cylinder device III includes: cylinder 31, piston 32, piston extension spring 33. The cylinder block 31 is fixed to the engine, the top of the cylinder block 31 is closed, the bottom of the cylinder block 31 is open, a cylinder block oil inlet and outlet hole 311 is formed in the cylinder wall of the cylinder block 31, and the cylinder block oil inlet and outlet hole 311 is connected to the pressure transfer oil passage L. The piston 32 is slidably disposed in an inner cavity of the cylinder 31, a cylinder oil cavity B is formed between the top of the piston 32 and the top of the cylinder 31, the cylinder oil inlet and outlet hole 311 is communicated with the cylinder oil cavity B, a piston rod 321 is disposed at the bottom of the piston 32, a piston step is formed at a transition position between the piston 32 and the piston rod 321, the piston rod 321 extends out of an opening of the cylinder 31, a diameter d of the piston 32 is reasonably designed, and it is ensured that thrust generated by engine oil pressure P1 on the piston 32 is far smaller than valve spring force. The piston tension spring 33 is located in the cylinder oil chamber B and connected between the top of the cylinder 31 and the top of the piston 32, and the pulling force of the piston tension spring 33 is much greater than the pushing force of the oil pressure P2 to the piston 32, but much smaller than the pushing force of the oil pressure P1 to the piston 32.

As shown in fig. 6, a block oil drain hole 312 is further provided in the cylinder wall of the block 31, and the block oil drain hole 312 communicates with the oil pan 60 of the engine. On one hand, the engine oil in the oil chamber B of the cylinder body can flow through the oil drain hole 312 of the cylinder body to drain a part of the engine oil, so that part of heat is taken away, and the oil in the oil cylinder device III is prevented from being too high in temperature. On the other hand, the cylinder oil drain hole 312 also plays a role of limiting the position of the piston 32, as shown in fig. 6, the thrust of the high-pressure engine oil P to the piston 32 is greater than the elastic force of the piston tension spring 33, the high-pressure engine oil in the cylinder oil cavity B pushes the piston 32 to move downward, when the piston 32 moves downward to a certain position, the top edge of the cylinder oil drain hole 312 begins to be higher than the top surface of the piston 32, the oil drain area formed by the oil hole edge and the top surface of the piston will drain off a part of the engine oil, so that the oil pressure decreases, the piston 32 continues to move downward, the oil flow area formed by the oil hole edge and the top surface of the piston gradually increases, the oil pressure continues to decrease, when the thrust of the oil pressure to the piston 32 is equal to the elastic force of the piston tension spring 33, at this time, the piston 32 will not move downward any more.

As shown in fig. 7, in addition to fig. 6, a piston stopper 313 for limiting the axial movement of the piston 32 is further provided at the open end of the cylinder 31. The design of the piston limiting device 313 ensures that when the piston 32 is limited, the top edge of the cylinder oil drainage hole 312 slightly protrudes out of the top surface of the piston 32, but the piston 32 does not reach a balance position yet, and at the moment, the cylinder oil drainage hole 312 only plays a role in oil drainage and temperature reduction.

The piston position limiter 313 may be a closed ring, an unclosed ring, or a strip, and the shape thereof is not limited herein.

As shown in fig. 1, the pressure transmission oil path L is further connected to a low-pressure relief oil path, the low-pressure relief oil path is provided with a low-pressure relief valve 90 and an overflow pressure retaining valve 200, the low-pressure relief valve 90 is connected to the pressure transmission oil path L, and the overflow pressure retaining valve 200 is connected to an oil pan 60 of the engine; the pressure relief pressure of the low-pressure relief valve 90 is not higher than P1, and the pressure relief pressure of the low-pressure relief valve 90 is slightly higher than P2.

As shown in fig. 8, the low pressure relief valve 90 includes: valve body 91, valve ball 92, compression spring 93, spacer pin 94. The valve body 91 is provided with a valve body oil inlet and a valve body oil outlet which are communicated with the valve cavity of the valve body, the valve body oil inlet is connected with the pressure transmission oil path L, and the valve body oil outlet is connected with the overflow pressure retaining valve 200; the valve ball 92, the compression spring 93 and the limit pin 94 are all arranged in the valve cavity, the compression spring 93 is clamped between the valve ball 92 and the valve body oil outlet, and the limit pin 94 is located between the valve body oil inlet and the valve ball 92.

As shown in fig. 8, the oil enters from the oil inlet of the valve body, and if the thrust of the inlet/outlet oil pressure difference to the valve ball 92 is greater than the acting force of the compression spring 93, the valve ball 92 is sealed on the inner conical surface of the valve cavity, and the low-pressure relief valve 90 is in a closed state. As shown in fig. 9, if the thrust of the inlet/outlet oil pressure difference to the valve ball 92 is lower than the acting force of the compression spring 93, the valve ball 92 is separated from the inner conical surface of the valve cavity, the oil flows, and the low-pressure relief valve 90 is in an open state. Since the outlet pressure is set to a fixed value by the relief pressure retaining valve 300, the low pressure relief valve 90 seals when the inlet pressure is higher than a certain value, and loses its sealing effect when the oil pressure is lower than a certain value, which is called relief pressure.

In one embodiment, the cam 16 may be an exhaust cam on a camshaft; cam 16 may also be an intake cam on a camshaft; the cams 16 can also be single-cylinder braking cams, dedicated to braking, the number of which is the same as the number of cylinders of the engine. No matter the exhaust cam, the air inlet cam or the single-cylinder brake cam is adopted, when braking is carried out in a cylinder, the brake cam can be used for abutting against and pushing the plunger 22 of the oil pumping device II, so that the engine oil pressure in the oil cavity A of the plunger sleeve is increased, high-pressure engine oil is pumped to the oil cylinder device III through the pressure transmission oil way L, the oil cylinder device III pushes the rocker arm 12 to swing downwards to open the valve 10, and the braking in the cylinder is realized.

The utility model discloses a braking system working process in compression release formula engine jar as follows:

as shown in fig. 1, when the engine enters the in-cylinder braking mode, the electromagnetic directional valve 80 is energized, and the engine oil with the pressure of P1 enters the pressure transmission oil path L through the electromagnetic directional valve 80 and the check valve 40, and enters the oil cylinder device III and the oil pumping device II respectively;

under the action of the oil pressure P1, the piston 32 in the oil cylinder device III overcomes the force of the piston tension spring 33, and the piston rod 321 extends to abut against the top end of the rocker arm 12 but cannot abut against the valve 10;

under the action of the oil pressure P1, the plunger 22 in the oil pumping device II overcomes the acting force of the plunger tension spring 23, and the plunger step extends to the position of the plunger limiting device 213;

the low pressure relief valve 90 is closed;

the camshaft rotates, when the camshaft rotates to the position shown in fig. 1, the cam 16 abuts against the top surface of the oil pumping device II and pushes the plunger 22 to move, at the beginning, because the plunger sleeve buffer oil hole 212 is not blocked by the plunger 22, the engine oil in the plunger sleeve oil cavity a of the oil pumping device II leaks through the plunger sleeve buffer oil hole 212, because the engine oil pressure is lower, the thrust generated to the plunger 22 is smaller, the reaction force of the plunger 22 to the cam 16 is smaller, and as the area of the plunger 22 blocking the plunger sleeve buffer oil hole 212 is larger and larger, the oil pressure is increased continuously, the reaction force of the plunger 22 to the cam 16 is increased continuously, in the process, because the reaction force is a gradually increasing process, the buffer effect is achieved through the plunger sleeve buffer oil hole 212, and the impact caused by the sudden contact of the cam 16 and the top surface of the oil pumping device II is reduced;

before the plunger sleeve buffer oil hole 212 is completely blocked, part of oil in the oil pumping device II is discharged through the plunger sleeve buffer oil hole 212;

after the plunger sleeve buffer oil hole 212 is completely blocked, the oil pumping device II starts pumping oil, and high-pressure engine oil P is transferred into a cylinder oil cavity B of the oil cylinder device III through a pressure transfer oil way L to push the piston 32 to move downwards to open the valve 10 to complete pressure release;

the cam 16 continues to rotate, after the cam rotates to the highest point, the piston 32 pushes the rocker arm 12 downwards to reach the limit position, the distance between the piston 32 and the limiting device is S, S is a safe distance, and S is greater than 0, as shown in fig. 1, the cylinder oil drainage hole 312 is completely blocked by the piston 32, and oil drainage is not performed (the oil pressure in the cylinder oil cavity B is too high, oil drainage is not desired);

the cam 16 continues to rotate, the top surface of the plunger of the oil pumping device II is gradually separated from the cam 16, the plunger 22 moves towards the cam 16 under the action of the oil pressure P1, the pressure in the plunger sleeve oil cavity A is reduced, and the plunger sleeve buffer oil hole 212 is gradually communicated with the plunger sleeve oil cavity A; the piston 32 in the cylinder device III gradually returns to the original position under the action of the valve spring force, the valve 10 is closed, and a braking process is finished.

As shown in fig. 2, the cam 16 continues to rotate and jacks the tappet 15 and the push rod 14 to move, the top of the rocker arm 12 is separated from the piston rod 321, the piston 32 moves to a limit position under the action of the oil pressure P1, at this time, the top of the piston 32 is slightly lower than the top edge of the cylinder oil drainage hole 312, and the cylinder oil drainage hole 312 begins to drain oil; the cam 16 continues to rotate again, the valve 10 is gradually closed, the rocker arm 12 pushes against the piston rod 321 again, the piston 32 is pushed to move upwards under the action of the valve spring force, the engine oil in the oil cylinder device III is transmitted to the oil pumping device II through the pressure transmission oil path L, and is leaked out through the plunger sleeve buffer oil hole 212 in the oil pumping device II.

In this process, the closing moment of the valve 10 may be slightly delayed by the reaction force of the piston 32 in the cylinder device III against the rocker arm 12, which is advantageous in the in-cylinder braking state, in which the total charge into the cylinder is increased by the additional intake of a certain charge into the cylinder through the exhaust valve in the subsequent intake stroke, and the braking power is increased in the compression stroke.

As shown in fig. 3, the electromagnetic directional valve 80 is powered off, the pressure transmission oil path L is communicated with the low-pressure oil path of the oil supply device IV, the oil supply device IV will provide low-pressure engine oil with a pressure of P2, at this time, the cam 16 continues to rotate to push the oil pumping device II and the oil cylinder device III to work once, because before the plunger sleeve buffer oil hole 212 of the oil pumping device II is blocked, a part of the engine oil in the plunger sleeve oil chamber a is discharged through the plunger sleeve buffer oil hole 212, after the oil pumping is finished, the plunger 22 moves towards the cam 16, the plunger sleeve oil chamber a increases, and the engine oil pressure in the pressure transmission oil path L gradually decreases; during the normal opening of the valve shown in fig. 2, a part of the oil is also drained through the cylinder device III, resulting in a further reduction in the oil pressure in the pressure-transmitting oil passage L; before the pressure in the oil cylinder device is reduced to P2, the oil supply device IV can not supply oil for the pressure transmission oil path L, after the pressure is reduced to P2, the low-pressure relief valve 90 is opened to further release the oil in the oil cylinder device, so that the oil pressure in the pressure transmission oil path L is maintained at P2, the plunger 22 in the oil pumping device II returns under the action of the plunger tension spring 23, the piston 32 in the oil cylinder device III returns under the action of the piston tension spring 33 to the position shown in FIG. 3, and the in-cylinder braking process is finished.

Example two

As shown in fig. 10, a compression-release engine in-cylinder brake system according to a second embodiment of the present invention is substantially the same as the first embodiment, except that: the cam for abutting against and pushing the plunger 22 of the oil pumping device II is a total braking cam 16a, the total braking cam 16a is a cam additionally arranged at a proper position on a cam shaft, and the cam is different from an original exhaust cam and an original intake cam on the cam shaft; and, oil pumping means II corresponding to all the cylinders of the engine are arranged around the master brake cam 16a, the number of oil pumping means II being the same as the number of cylinders of the engine.

Fig. 10 is an example of a six-cylinder engine, and illustrates a case where the oil pumping devices II of six cylinders of the engine are arranged around the master brake cam 16 a.

Obviously, the utility model discloses a braking system in compression release formula engine jar is not limited to the six jar engines that are shown in fig. 1 and fig. 10, the utility model discloses a braking system in compression release formula engine jar does not receive the restriction of cylinder quantity, and cylinder quantity can increase and decrease to some extent on the basis of six jars. The number of cylinders may be even or odd.

The utility model discloses show the exhaust braking scheme of putting the engine under the camshaft, to the engine of camshaft side-mounting, camshaft overhead structure, can refer to the realization equally.

The foregoing is an example of the preferred embodiment of the present invention, and those parts not described in detail are known to those skilled in the art, and the scope of the present invention is defined by the appended claims, and all equivalent changes that can be made based on the teachings of the present invention are within the scope of the present invention.

Claims

1. Compression release formula engine in-cylinder braking system applies to the valve train of engine, includes: the engine comprises an oil cylinder device, an oil pumping device and an oil supply device, wherein all cylinders of the engine share one oil supply device;

the oil supply device comprises an electromagnetic directional valve, an oil supply path, a pressure reducing path and a pressure reducing path, wherein an overflow pressure retaining valve is arranged in the pressure reducing path, a pressure reducing valve is arranged in the pressure reducing path, and the engine oil pressure of the engine before pressure reduction is defined as P1 and the engine oil pressure of the engine after pressure reduction is defined as P2; it is characterized in that the preparation method is characterized in that,

each cylinder is respectively provided with the oil cylinder device and the oil pumping device, the oil cylinder device is communicated with the oil pumping device through a pressure transmission oil way, and the pressure transmission oil way is communicated with the oil supply oil way through a one-way valve.

2. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said oil pumping means includes:

3. The compression-release engine in-cylinder brake system according to claim 2, wherein a plunger sleeve buffer oil hole is further formed in a sleeve wall of the plunger sleeve, the plunger sleeve buffer oil hole is communicated with an oil pan of an engine through an overflow pressure-maintaining valve, and the plunger sleeve buffer oil hole is communicated with the plunger sleeve oil chamber when the in-cylinder brake cam pushes up the valve; when the brake is not carried out in the cylinder, the plunger piston plugs the plunger sleeve buffer oil hole under the action of the plunger piston tension spring.

4. The compression-release engine in-cylinder brake system as defined in claim 2, wherein the open end of said plunger sleeve is provided with a plunger stop; the plunger comprises a plunger large-diameter section and a plunger small-diameter section, the plunger large-diameter section is located in an inner cavity of the plunger sleeve, the plunger small-diameter section is connected with the plunger large-diameter section, a plunger step is formed at the transition position of the plunger large-diameter section and the plunger small-diameter section, and the plunger limiting device limits the plunger step during braking in the cylinder.

5. The compression-release engine in-cylinder brake system according to claim 4, wherein the plunger further comprises a plunger abutting section located outside the plunger barrel and connected to the plunger small-diameter section, a top surface of the plunger abutting section abutting against the cam when in-cylinder braking; when the brake is not performed in the cylinder, the top surface of the plunger abutting section is separated from the cam, and the plunger limiting device limits the plunger abutting section.

6. The compression-release engine in-cylinder brake system as defined in claim 5, wherein the top surface of the plunger abutting section is a flat surface or an arc surface.

7. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said cylinder device includes:

8. The compression-release engine in-cylinder braking system according to claim 7, wherein a cylinder block oil drain hole is further provided in the cylinder wall of the cylinder block, and the cylinder block oil drain hole communicates with an oil pan of the engine.

9. The compression-release engine in-cylinder brake system as defined in claim 8, wherein the open end of said cylinder body is provided with a piston stopper; a piston step is formed at the transition position of the piston and the piston rod, when the oil pumping device is braked in the cylinder to work, the piston limiting device does not limit the piston step, the distance between the piston step and the piston limiting device is S, and S is larger than 0;

10. The in-cylinder brake system of a compression-release engine according to claim 1, wherein the pressure transmission oil path is further connected with a low-pressure-release oil path, the low-pressure-release oil path is provided with a low-pressure relief valve and an overflow pressure-retaining valve, the low-pressure relief valve is connected with the pressure transmission oil path, and the overflow pressure-retaining valve is connected with an oil pan of the engine; the pressure relief pressure of the low-pressure relief valve is not higher than P1, and the pressure relief pressure of the low-pressure relief valve is higher than P2.

11. The compression-release engine in-cylinder brake system as defined in claim 10, wherein the low pressure relief valve includes:

a valve ball disposed within the valve cavity;

12. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said cam is an exhaust cam; alternatively, the cam is an intake cam; alternatively, the cam is a single cylinder brake cam.

13. The compression-release engine in-cylinder brake system according to claim 1, wherein the cam is a master brake cam, and the oil pumping means is provided around the master brake cam in the same number as the number of cylinders of the engine.