CN209892285U

CN209892285U - Valve bridge capable of realizing compression release type engine braking

Info

Publication number: CN209892285U
Application number: CN201920699157.6U
Authority: CN
Inventors: 黄瑞; 陈俊玄; 吴启超; 童宇翔; 俞小莉
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-05-15
Filing date: 2019-05-15
Publication date: 2020-01-03
Anticipated expiration: 2029-05-15

Abstract

The utility model relates to an engine braking technical field, concretely relates to can realize valve bridge of compression release formula engine braking. The valve bridge mainly comprises a valve bridge body, a one-way valve, a driving plunger and a driven plunger. The valve bridge body is provided with a first plunger cavity for installing a driving plunger, a second plunger cavity for installing a driven plunger, an oil discharge duct and a connecting oil duct. The inside of the active plunger is provided with a one-way valve, and the active plunger is provided with an active plunger oil discharge channel. An elastic piece and a driving plunger oil cavity are arranged between the driving plunger and the first plunger cavity, and the driving plunger oil cavity is communicated with the driving plunger oil discharging channel. The connecting oil duct is communicated with the driving plunger oil cavity and the driven plunger oil cavity. The utility model provides a valve bridge both can realize under same cam that the exhaust valve normally works at the exhaust braking in-process, can also realize compression release formula engine braking function.

Description

Valve bridge capable of realizing compression release type engine braking

Technical Field

The patent of the utility model relates to an engine braking technical field, concretely relates to can realize the valve bridge of compression release formula engine braking.

Background

Compression release type engine braking is a currently mainstream engine braking technology, has high braking power, and is generally applied to some commercial vehicles, for example, in the process of long downhill, a control switch is turned on, oil is stopped, the engine is stalled, an exhaust valve is opened when the piston is close to the vicinity of an upper dead center in the later stage of a compression stroke, high-pressure gas is discharged, and most of energy absorbed by the compressed gas is discharged. Compression-release engine braking achieves a braking effect through energy consumption.

One prior example of an engine braking device is the hydraulic engine brake disclosed in U.S. patent No. 3220392 to Cummins (Cummins) 1965. In this technique, mechanical input is transmitted to the exhaust valve to be opened via a hydraulic circuit. The hydraulic circuit typically includes a master piston reciprocating in a master piston bore, the reciprocating motion resulting from mechanical input to the engine, such as rocking of an injection rocker arm, the motion of the master piston being transmitted by hydraulic fluid to a slave piston for reciprocating movement in a slave piston bore, the slave piston acting directly or indirectly on an exhaust valve to produce valve actuation for engine braking operation.

Disclosure of Invention

An object of the utility model is to provide a can realize valve bridge of compression release formula engine braking, simple structure both can realize under same cam that the exhaust valve normally works, can also realize compression release formula engine braking function.

The utility model firstly discloses a valve bridge capable of realizing the brake of a compression release type engine, which comprises a valve bridge body, a one-way valve, a driving plunger and a driven plunger;

the valve bridge body is provided with a first plunger cavity for mounting a driving plunger, a second plunger cavity for mounting a driven plunger, an oil discharge duct and a connecting oil duct; the active plunger is internally provided with a one-way valve and is provided with an active plunger oil discharge channel; an elastic piece and a driving plunger oil cavity are arranged between the driving plunger and the first plunger cavity, and the driving plunger oil cavity is communicated with the driving plunger oil discharging channel; the connecting oil duct is communicated with the driving plunger oil cavity and the driven plunger oil cavity; the active plunger can move up and down in the first plunger cavity; the movement of the driving plunger in the stroke range of the driving plunger enables the valve bridge to be in an oil unloading state and a non-oil unloading state, and when the valve bridge is in the oil unloading state, the oil unloading oil duct is communicated with the oil unloading channel of the driving plunger, so that the oil unloading oil duct is communicated with the connecting oil duct; when the oil discharge passage and the driving plunger oil discharge passage are in a non-communicated state, the valve bridge is in a non-oil discharge state.

According to the utility model discloses, when initiative plunger oil pocket with be connected when full of oil in the oil duct, because the effect of oil pressure, driven plunger can be owing to the downstream of initiative plunger and downstream.

According to the utility model discloses, when the initiative plunger position is suitable, the connection oil duct can be switched on mutually with the oil discharge duct through initiative plunger oil discharge groove to unload.

Preferably, the elastic element is a spring abutting between the bottom of the first plunger cavity and the inside of the active plunger.

Preferably, the connecting oil channel is a three-way channel, and a first port of the connecting oil channel is communicated with the top of the oil cavity of the driven plunger; the second port is communicated with the bottom of the oil cavity of the active plunger; and the third port is communicated with the oil unloading channel through the driving plunger oil unloading channel when the valve bridge is in an oil unloading state.

Preferably, the active plunger oil discharge channel is two pore channels arranged on the wall surface of the active plunger; the pore passages are communicated with the active plunger oil cavity, when the active plunger oil cavity is in an oil unloading state, one pore passage is communicated with the oil unloading oil passage, and the other pore passage is communicated with the connecting oil passage.

The exhaust braking process of the valve bridge is as follows: starting an engine brake control switch, starting oil supply of the system, and enabling the oil to enter an oil cavity of the active plunger through a one-way valve in the active plunger; when the engine is close to the top dead center in the later stage of the compression stroke, the driving plunger moves downwards due to the shape of the cam, the oil pressure in the oil cavity of the driving plunger, the connecting oil duct and the oil cavity of the driven plunger rises, the driven plunger is pushed to move downwards, an exhaust valve of the engine is jacked open, and high-pressure gas is released;

when the driving plunger further moves downwards, the connecting oil duct is communicated with the oil unloading oil duct, the valve bridge is in an oil unloading state, so that pressure oil in the oil cavity of the driven plunger and the oil cavity of the driving plunger is unloaded, the oil pressure is reduced, the driven plunger moves upwards to return, the exhaust valve is closed, and the braking process of the compression release type engine in the cycle is finished; after the exhaust stroke of the engine is finished, the driving plunger moves upwards and returns under the action of the elastic piece due to the shape of the cam, negative pressure is formed in an oil cavity of the driving plunger, and oil pressure in the oil cavity of the driving plunger is recovered due to continuous oil supply of a system to prepare for entering the next cycle.

Furthermore, if the engine brake control switch is closed and oil supply is stopped, the oil pressure in the oil cavity of the driving plunger cannot be maintained, the driven plunger does not move downwards any more when the driving plunger moves downwards, the exhaust valve cannot be opened in the later stage of the compression stroke of the engine, the brake function of the compression release type engine fails, and the exhaust valve is opened after the elephant foot is in rigid contact with the valve bridge in the exhaust stroke of the engine, so that the engine is not different from an engine without the exhaust brake function.

The utility model has the advantages that the valve bridge which can realize the compression release type engine brake has ingenious design and simple structure, under the same cam, if the engine brake is closed, namely when the system does not supply oil, the exhaust valve can be normally opened and closed, and the valve bridge has no difference with the general engine without the exhaust brake function; if the engine brake is started and the system supplies oil, the exhaust brake function can be realized at the later stage of the compression stroke of the engine, and the exhaust valve timing and lift of the exhaust stroke cannot be influenced.

Drawings

Fig. 1 is a schematic structural view of a valve bridge capable of realizing braking of a compression-release engine according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of the valve bridge in the embodiment of the present invention in the exhaust braking state;

FIG. 3 is a schematic structural view of the valve bridge in the embodiment of the present invention in the oil unloading state, i.e., when the connecting oil passage is communicated with the oil unloading passage through the active plunger oil unloading passage;

fig. 4 is a schematic view of the cam and the rocker arm and other auxiliary mechanisms engaged with the embodiment of the present invention when the valve bridge is in the exhaust braking state;

description of the labeling: 1-one-way valve, 2-driving plunger, 3-driving plunger oil discharge channel, 4-driving plunger oil cavity, 5-oil discharge channel, 6-connecting oil channel, 7-plug, 8-driven plunger, 9-valve bridge body, 10-elastic part, 11-first plunger cavity, 12-second plunger cavity, 13-driven plunger oil cavity, 14-elephant foot, 15-adjusting screw, 16-rocker arm, 17-roller, 18-cam and 19-exhaust valve.

Detailed Description

The following describes the embodiments of the present invention with reference to the accompanying drawings.

As shown in fig. 1, 2 and 3: a valve bridge capable of realizing compression release type engine braking mainly comprises a one-way valve 1, a driving plunger 2, a driving plunger oil unloading channel 3, a driving plunger oil cavity 4, an oil unloading oil channel 5, a connecting oil channel 6, a plug 7, a driven plunger 8, a valve bridge body 9, an elastic piece 10, a first plunger cavity 11, a second plunger cavity 12 and a driven plunger oil cavity 13. The valve bridge body 9 is provided with a first plunger cavity 11 for installing the driving plunger 2, a second plunger cavity 12 for installing the driven plunger 8, an oil discharge duct 5 and a connecting oil duct 6, and the surface of the valve bridge body 9 is provided with a plug 7 for sealing and processing a duct. The active plunger 2 is internally provided with a one-way valve 1, and the active plunger 2 is provided with an active plunger oil discharge channel 3. An elastic piece 10 and an active plunger oil chamber 4 are arranged between the active plunger 2 and the first plunger chamber 11, and the active plunger oil chamber 4 is communicated with the active plunger oil discharge channel 3. And the connecting oil duct 6 is communicated with the driving plunger oil cavity 4 and the driven plunger oil cavity 13.

And starting an engine brake control switch, starting and continuously supplying oil to the system, and enabling the oil to enter the oil cavity 4 of the active plunger through the one-way valve 1 to be full and form certain oil pressure. The follower plunger 8 remains in place and does not move down as shown in figure 1.

When the later stage of the compression stroke of the engine is close to the top dead center, the driving plunger 2 starts to move downwards due to the shape of the cam 18, and the oil pressure in the driving plunger oil cavity 4, the connecting oil channel 6 and the driven plunger oil cavity 13 rises due to the downward movement of the driving plunger 2, so that the driven plunger 8 is pushed to move downwards, the exhaust valve 19 is opened, and high-pressure gas is released, as shown in fig. 2 and 4. The oil discharge state is firstly achieved in the process that the driving plunger 2 moves further downwards, the connecting oil duct 6 is communicated with the oil discharge duct 5 through the driving plunger oil discharge channel 3, pressure oil flows out of the oil discharge duct 5, the oil pressure in the driving plunger oil chamber 4 and the connecting oil duct 6 is reduced, the driven plunger 8 moves upwards and returns, the exhaust valve 19 is closed, and the compression release type engine braking process in the cycle is finished. The adjusting screw 15 is moved downwards until the elephant foot 14 is in rigid contact with the valve bridge body 9, at the moment, as shown in figure 3, then the expansion stroke is started, the piston in the engine cylinder moves downwards, energy is consumed when most high-pressure gas is exhausted, braking is facilitated when the piston moves downwards, then the exhaust stage is ready to be started, and due to the shape of the cam 18, the elephant foot 14 is in rigid contact with the valve bridge body 9, and therefore the exhaust valve 19 can be normally opened early and closed late. In order to play a buffering effect, the exhaust stroke is ended, the elephant foot 14 is still in rigid contact with the valve bridge body 9 in a short time after the exhaust valve 19 is closed, then the active plunger 2 moves upwards due to the action of the elastic piece 10, then the oil discharge state is removed, negative pressure is formed in the active plunger oil cavity 4, and due to continuous oil supply of the system, the oil pressure in the active plunger oil cavity 4 can be recovered, and the next circulation is ready to enter.

If the engine brake control switch is closed and oil supply is stopped, the oil pressure in the oil cavity 4 of the driving plunger is difficult to maintain, after a plurality of cycles, the driving plunger 2 moves downwards quickly, so that the driven plunger 8 can not move downwards through the oil pressure any more, the exhaust valve 19 cannot be opened in the later stage of the compression stroke of the engine, the brake function of a compression release type engine fails, and the phenomenon that the exhaust valve 19 is opened after the elephant foot 14 is in rigid contact with the valve bridge body 9 is the same as that of a common engine without the exhaust brake function.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, various modifications will be apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A valve bridge capable of realizing compression release type engine braking is characterized in that: comprises a valve bridge body, a one-way valve, a driving plunger and a driven plunger;

2. The compression-release engine brake-able valve bridge according to claim 1, wherein: the elastic piece is a spring which is abutted between the bottom of the first plunger cavity and the interior of the active plunger.

3. The compression-release engine brake-able valve bridge according to claim 1, wherein: the connecting oil duct is a three-way passage, and a first port of the connecting oil duct is communicated with the top of the driven plunger oil cavity; the second port is communicated with the bottom of the oil cavity of the active plunger; and the third port is communicated with the oil unloading channel through the driving plunger oil unloading channel when the valve bridge is in an oil unloading state.

4. The valve bridge of claim 1, wherein the oil discharge passage of the driving plunger is formed by two holes formed in the wall surface of the driving plunger; the pore passages are communicated with the active plunger oil cavity, when the active plunger oil cavity is in an oil unloading state, one pore passage is communicated with the oil unloading oil passage, and the other pore passage is communicated with the connecting oil passage.