CN107605563B

CN107605563B - Auxiliary braking mechanism

Info

Publication number: CN107605563B
Application number: CN201710775960.9A
Authority: CN
Inventors: 崔靖晨; 隆武强; 田华; 王阳; 许多
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2017-09-01
Filing date: 2017-09-01
Publication date: 2020-08-14
Anticipated expiration: 2037-09-01
Also published as: CN107605563A

Abstract

An auxiliary braking mechanism belongs to the field of engine valve driving, cylinder deactivation and auxiliary braking. The device comprises an air inlet/exhaust valve assembly, an air inlet/exhaust brake cam, an air inlet/exhaust driving cam, an air inlet/exhaust brake rocker arm and an air inlet/exhaust driving rocker arm; it also includes air inlet/outlet driving component, air inlet/outlet braking component and air inlet/outlet slide valve, etc. which are set on the fixing component. By controlling the states of the driving assembly and the braking assembly, the modes of four-stroke driving, two-stroke braking, cylinder deactivation and the like are realized, and the purposes of low oil consumption, low emission and high-efficiency braking of the engine are achieved. The invention has the advantages of small quantity of moving parts, compact structure, high reliability, low energy consumption, zero leakage and wide application range.

Description

Auxiliary braking mechanism

Technical Field

The invention relates to an auxiliary braking mechanism, and belongs to the field of engine valve driving, cylinder deactivation and auxiliary braking.

Background

With the rapid increase of the engine holding capacity, the safety of the vehicle is more and more emphasized by people, and more countries list the auxiliary brake system as one of the necessary accessories of the vehicle. However, the main brake system and the auxiliary brake system acting on the transmission system mostly have the problems that brake components are easy to overheat after long-time work, the brake efficiency is rapidly reduced, the brake system occupies the vehicle space and the like. The engine auxiliary braking technology does not have the problems, but the braking power of the prior art is low, and the requirements of a vehicle on a long slope and a steep slope under heavy load cannot be met. Especially, engine miniaturization (Down-size) and low-speed (Down-speed) have become the development trend of recognized energy conservation and emission reduction; on the other hand, in engine braking, the smaller the cylinder diameter and the lower the rotational speed, the poorer the braking effect thereof, and therefore, the two-stroke braking mode is inevitable. Under the four-stroke driving mode and the two-stroke braking mode of the engine, the opening frequency, the opening timing and the opening duration of an intake/exhaust valve are greatly different, and the existing variable valve driving system cannot meet the requirements.

All can bobo company proposed an HPD mechanism that enables flexible switching between four-stroke drive mode and two-stroke brake mode of the engine. The company (SAE 2016-01-8061) reported that the HPD mechanism had problems such as leakage. In addition, the mechanism also has the problems of large quantity of moving parts, large mass and the like caused by the fact that the driving and braking adjusting mechanisms are both arranged on the rocker arm, which is not beneficial to realizing low energy consumption of the valve driving system; in addition, the moving inertia force of the rocker arm is large, and the contact parts of the components of the system are easy to break. The driving oil of the mechanism is led to the rocker arm moving fulcrum from the inside of the shaft as the rocker arm fixing fulcrum to adjust the driving and braking adjusting mechanism, the oil path is complex, and the processing is difficult. The auxiliary brake mechanism is compact in structure, high in reliability, low in energy consumption, zero in leakage, convenient to modify an engine and capable of achieving mutual switching among a four-stroke driving mode, a two-stroke brake mode and a cylinder deactivation mode.

Disclosure of Invention

The invention aims to: by designing an auxiliary braking mechanism for realizing: (a) in order to achieve the operation of low oil consumption, low emission and efficient braking of the engine, the mechanism is required to realize a four-stroke driving mode, a two-stroke braking mode, cylinder deactivation and other modes. (b) In order to meet market demands, the mechanism is required to realize compact structure, reliable work, low energy consumption, zero leakage, convenience in engine modification and the like. (c) In order to expand the application range, different arrangement modes need to be provided for different models. (d) In order to improve the universality and replaceability of parts, each component needs to be designed into a standard part or a separate module.

The technical scheme adopted by the invention is as follows: an auxiliary brake mechanism comprises a first exhaust valve assembly, a second exhaust valve assembly, a first intake valve assembly, a second intake valve assembly, a cam, a rocker arm, a brake rocker arm spring, a driving assembly, a brake assembly and a slide valve, wherein the driving assembly, the brake assembly and the slide valve are installed on a fixing piece. The cam comprises an exhaust brake cam, an exhaust driving cam, an intake brake cam and an intake driving cam, the rocker arms comprise an exhaust brake rocker arm, an exhaust driving rocker arm, an intake brake rocker arm and an intake driving rocker arm, the driving assembly comprises an exhaust driving assembly and an intake driving assembly, the brake assembly comprises an exhaust brake assembly and an intake brake assembly, and the slide valve comprises an exhaust slide valve and an intake slide valve. The fixing piece is also provided with a brake control cavity, a brake oil release cavity and a drive control cavity, and the brake oil release cavity is always in a low-pressure state. The exhaust brake rocker arm spring provides spring force to drive the exhaust brake rocker arm to be in contact with the exhaust brake cam at the moment, and the intake brake rocker arm spring provides spring force to drive the intake brake rocker arm to be in contact with the intake brake cam at the moment. When the driving control cavity is in a high-pressure state, the exhaust driving assembly and the intake driving assembly are in a failure state; when the driving control cavity is in a low-pressure state, the exhaust driving assembly and the air inlet driving assembly are in working states. The exhaust slide valve controls the communication state of the oil cavity of the exhaust brake assembly with the brake control cavity and the brake oil release cavity, and the air inlet slide valve controls the communication state of the oil cavity of the air inlet brake assembly with the brake control cavity and the brake oil release cavity. When the brake control cavity is in a high-pressure state, the exhaust brake assembly and the air inlet brake assembly are in working states; when the brake control chamber is in a low-pressure state, the exhaust brake assembly and the air inlet brake assembly are in failure states. The exhaust brake cam drives the first exhaust valve assembly through the exhaust brake rocker arm, the exhaust brake assembly and the exhaust transmission block. The exhaust driving cam directly drives the second exhaust valve component after passing through the exhaust driving rocker arm and the exhaust driving component, and drives the first exhaust valve component through the exhaust transmission block. The intake brake cam drives the first intake valve assembly through the intake brake rocker arm, the intake brake assembly and the intake transmission block. The air inlet driving cam directly drives the second air inlet valve assembly after passing through the air inlet driving rocker arm and the air inlet driving assembly, and drives the first air inlet valve assembly through the air inlet transmission block. In the drive mode, both the drive control chamber and the brake control chamber are in a low pressure state. In the braking mode, the drive control chamber and the brake control chamber are both in a high pressure state. In the cylinder deactivation mode, the drive control chamber is in a high pressure state and the brake control chamber is in a low pressure state.

The drive assembly includes a drive piston, a valve bridge, a drive spring, a locking block, and a locking spring. The driving piston and the valve bridge are nested together, a driving spring is arranged between the driving piston and the valve bridge, one of the driving piston and the valve bridge is provided with a locking hole, and the other one of the driving piston and the valve bridge is provided with a locking ring groove and a locking oil hole. Two locking blocks and a locking spring are arranged in the locking hole, and the locking spring is arranged between the two locking blocks. The locking ring groove is communicated with the driving control cavity through a locking oil hole. The driving rocker arm is in contact with the driving piston, the valve bridge directly drives the second valve assembly, and the valve bridge drives the first valve assembly through the transmission block.

The brake assembly includes a brake spring, a brake lower piston, and a brake upper piston. The brake rocker arm is in contact with the brake upper piston, and the brake lower piston drives the first valve assembly through the transmission block.

The spool valve includes a spool valve body, a check valve, and a spool valve spring.

The transmission block comprises a first transmission block or a second transmission block. The first transmission block is connected with the valve bridge in a sliding mode, the valve bridge drives the first valve assembly through the ring platform of the first transmission block, and the piston drives the first valve assembly through the top end of the first transmission block under braking. The second transmission block is hinged with the valve bridge, the valve bridge drives the first valve assembly through the input end of the second transmission block, and the piston drives the first valve assembly through the output end of the second transmission block under braking.

A tappet cup and a push rod are arranged between the cam and the rocker arm.

The invention has the beneficial effects that: this auxiliary braking mechanism can realize that: (a) the engine has multiple modes such as a four-stroke driving mode, a two-stroke braking mode, cylinder deactivation and the like, and achieves the running of low oil consumption, low emission and high-efficiency braking of the engine. (b) The driving assembly, the braking assembly, the sliding valve and the like are integrated on the fixing piece, so that the structure is compact, zero leakage is realized, and the engine is convenient to modify; the number of moving parts is reduced, the work is reliable, and the energy consumption is low. (c) The engine can be applied to a top camshaft engine and a bottom camshaft engine, and the application range is expanded. (d) The driving assembly, the braking assembly, the sliding valve and the like can be designed into independent modules, so that the universality and the replaceability of parts are improved.

Drawings

The invention is further described with reference to the following figures and examples.

Fig. 1 is a schematic view of an overhead camshaft type auxiliary brake mechanism.

Fig. 2 is a top view of an overhead camshaft type auxiliary brake mechanism.

Fig. 3 is a schematic view of a drive assembly.

Fig. 4 is a schematic view of a second drive block.

FIG. 5 is a schematic view of a slide valve.

FIG. 6 is a schematic view of a bottom mounted cam shaft type auxiliary braking mechanism.

In the figure: A. a fixing member; BC. A brake control chamber; BT, a brake oil release cavity; DC. A drive control chamber; CB1, exhaust brake cam; CD1, exhaust drive cam; CB2, intake brake cam; CD2, intake drive cam; RB1, exhaust brake rocker arm; RD1, exhaust drive rocker arm; RB2, an air intake brake rocker arm; RD2, intake drive rocker arm; VB1, first exhaust valve assembly; VD1, second exhaust valve assembly; VB2, first intake valve assembly; VD2, second intake valve assembly; BA1, exhaust brake assembly; DA1, exhaust drive assembly; HV1, exhaust spool valve; BA2, intake brake assembly; DA2, intake drive assembly; HV2, intake spool valve; BP11, exhaust brake upper piston; BP12, exhaust brake lower piston; BK1, exhaust brake spring; DP, driving the piston; DB. A valve bridge; DK. A drive spring; DLP, lock block; DLK, locking spring; DLB, drive block; HVP, spool valve body; CV, check valves; HVK, spool valve spring; DLBI and a second transmission block input end; DLBO, second transmission piece output.

Detailed Description

The invention relates to an auxiliary braking mechanism. Fig. 1 is a schematic view of an overhead camshaft type auxiliary brake mechanism, with a fixing member a cut away. Fig. 2 is a top view of the overhead camshaft type auxiliary brake mechanism with the fastener a hidden. The exhaust drive assembly DA1, exhaust brake assembly BA1, exhaust spool valve HV1, intake drive assembly DA2, intake brake assembly BA2 and intake spool valve HV2 are all mounted on mount a. The exhaust brake cam CB1 actuates the first exhaust valve assembly VB1 through the exhaust brake rocker arm RB1, the exhaust brake assembly BA1 and the exhaust transmission block. The exhaust drive cam CD1 directly drives the second exhaust valve assembly VD1 after passing through the exhaust drive rocker arm RD1 and the exhaust drive assembly DA1, and drives the first exhaust valve assembly VB1 through the exhaust transmission block. The intake brake cam CB2 drives the first intake valve assembly VB2 through the intake brake rocker arm RB2, the intake brake assembly BA2 and the intake transmission block. The intake driving cam CD2 directly drives the second intake valve assembly VD2 after passing through the intake driving rocker arm RD2 and the intake driving assembly DA2, and drives the first intake valve assembly VB2 through the intake transmission block. The fixing piece A is further provided with a brake control cavity BC, a brake oil release cavity BT and a drive control cavity DC, and the brake oil release cavity BT is always in a low-pressure state. The exhaust brake rocker arm spring RK1 provides a spring force urging the exhaust brake rocker arm RB1 into timed contact with the exhaust brake cam CB1, and the intake brake rocker arm spring RK2 urges the intake brake rocker arm RB2 into timed contact with the intake brake cam CB2 via a spring force.

Fig. 3 is a schematic view of a drive assembly. The drive assembly includes a drive piston DP, a valve bridge DB, a drive spring DK, a lock block DLP and a lock spring DLK. The driving piston DP and the valve bridge DB are nested together, a driving spring DK is arranged between the driving piston DP and the valve bridge DB, one of the driving piston DK and the valve bridge DB is provided with a locking hole, and the other one of the driving piston DK and the valve bridge DB is provided with a locking ring groove and a locking oil hole. Two locking blocks DLP and a locking spring DLK are arranged in the locking hole, and the locking spring DLK is arranged between the two locking blocks DLP. The locking ring groove is communicated with the driving control cavity DC through a locking oil hole. The driving rocker arm is in contact with the driving piston DP, the valve bridge DB directly drives the second valve assembly, and the valve bridge DB drives the first valve assembly through the transmission block DLB. When drive control chamber DC is the low pressure state, under locking spring DLK's effect, two locking piece DLPs will be in locking hole and locking ring inslot simultaneously, and drive piston DP and valve bridge DB are locked integratively, and drive assembly is in operating condition promptly, and the motion of drive cam will be passed through drive rocking arm, drive assembly and transmit two valves. When the driving control cavity DC is in a high-pressure state, the two locking blocks DLP are completely pressed into the locking holes, the driving piston DP and the valve bridge DB are mutually independent in movement, namely the driving assembly is in a failure state, and the movement of the driving cam cannot be transmitted to the two valves. As can be seen from fig. 1, when the driving control chamber DC is in a low-pressure state, the exhaust driving assembly DA1 and the intake driving assembly DA2 are in an operating state; when the drive control chamber DC is in a high-pressure state, the exhaust drive assembly DA1 and the intake drive assembly DA2 are in a failure state.

The brake assembly includes a brake spring, a brake lower piston, and a brake upper piston. The brake rocker arm is in contact with the brake upper piston, and the brake lower piston drives the first valve assembly through the transmission block DLB.

FIG. 5 is a schematic view of a slide valve. The spool valve includes a spool valve body HVP, a check valve CV, and a spool valve spring HVK. As can be seen in fig. 1, the exhaust spool valve HV1 controls the communication state of the oil chamber of the exhaust brake assembly BA1 with the brake control chamber BC and the brake drain chamber BT. When the brake control cavity BC is in a high-pressure state, the exhaust slide valve HV1 descends, the oil cavity of the exhaust brake assembly BA1 is not communicated with the brake relief cavity BT, hydraulic oil in the brake control cavity BC enters the oil cavity of the exhaust brake assembly BA1 through the check valve, and the exhaust brake assembly BA1 is in a working state. The motion of the exhaust brake cam CB1 will be transferred to the first exhaust valve assembly VB1 through the exhaust brake rocker arm RB1, the exhaust brake assembly BA1 and the exhaust transmission block. When the brake control cavity BC is in a low-pressure state, the exhaust slide valve HV1 moves upwards, the oil cavity of the exhaust brake assembly BA1 is not communicated with the brake control cavity BC, the oil cavity of the exhaust brake assembly BA1 is communicated with the brake drain oil cavity BT, hydraulic oil in the brake control cavity BC leaks into the brake drain oil cavity BT, and the exhaust brake assembly BA1 is in a failure state. The motion of the exhaust brake cam CB1 is not transmitted to the first exhaust valve assembly VB 1. Similarly, the intake spool valve HV2 controls the communication state of the oil chamber of the intake brake assembly BA2 with the brake control chamber BC and the brake drain chamber BT. When the brake control cavity BC is in a high-pressure state, the air inlet brake assembly BA2 is in a working state; when the brake control chamber BC is in the low pressure state, the intake brake assembly BA2 is in the failure state.

When the driving control cavity DC and the braking control cavity BC are in a low-pressure state, the engine is in a four-stroke driving mode; when the driving control cavity DC and the braking control cavity BC are in a high-pressure state, the engine is in a two-stroke braking mode; when the driving control cavity DC corresponding to some cylinders is in a high-pressure state and the braking control cavity BC is in a low-pressure state, the cylinders are in a cylinder deactivation mode, and the state of the engine is determined by the working modes of other cylinders; the invention provides the valve actuating mechanism for the running of the engine with low oil consumption, low emission and high-efficiency braking.

The drive block DLB includes a first drive block or a second drive block. Fig. 3 uses the first transmission block. First transmission piece and valve bridge DB sliding connection, valve bridge DB drive first valve subassembly through the loop platform of first transmission piece, and the piston drives first valve subassembly through the top of first transmission piece under the braking. Fig. 4 is a schematic view of a second drive block. The second transmission block is hinged to the valve bridge DB, the valve bridge DB drives the first valve assembly through a second transmission block input end DLBI, and the piston drives the first valve assembly through a second transmission block output end DLBO under the brake.

The driving assembly, the braking assembly, the sliding valve and the like in the invention can be designed into independent modules and are integrated on the fixing part A, so that the structure is compact, the leakage is zero, the engine is convenient to modify, and the universality and the replaceability of parts are realized. The spool valve does not move except for the mode switching interval; when the brake assembly fails, the brake assembly does not move; therefore, the invention has the advantages of reduced moving parts, reliable work and low energy consumption.

FIG. 6 is a schematic view of a bottom mounted cam shaft type auxiliary braking mechanism. A tappet cup and a push rod are arranged between the cam and the rocker arm. The invention can be used for overhead camshaft engines and bottom camshaft engines, and has wide application range.

Claims

1. An auxiliary brake mechanism comprises a first valve component, a second valve component, a brake cam, a driving cam, a brake rocker arm, a driving rocker arm and a brake rocker arm spring, and further comprises a driving component, a brake component and a slide valve which are arranged on a fixing component (A); the driving cam acts on the driving component through the driving rocker arm; the method is characterized in that: the drive assembly comprises a Drive Piston (DP), a valve bridge (DB), a drive spring (DK), a locking block (DLP) and a locking spring (DLK); the Driving Piston (DP) and the valve bridge (DB) are nested together, a driving spring (DK) is arranged between the driving piston and the valve bridge, one of the driving piston and the valve bridge is provided with a locking hole, and the other one of the driving piston and the valve bridge is provided with a locking ring groove and a locking oil hole; two locking blocks (DLP) and a locking spring (DLK) are arranged in the locking hole, and the locking spring (DLK) is arranged between the two locking blocks (DLP); the locking ring groove is communicated with a driving control cavity (DC) through a locking oil hole; the driving rocker arm is in contact with the Driving Piston (DP), the valve bridge (DB) directly drives the second valve assembly, and the valve bridge (DB) drives the first valve assembly through the transmission block (DLB); the brake cam drives the first valve component through the brake rocker arm, the brake component and the transmission block (DLB); the spring of the brake rocker arm provides spring force to drive the brake rocker arm to be in contact with the brake cam at any time.

2. An auxiliary brake mechanism according to claim 1, wherein: the brake assembly comprises a brake spring, a brake lower piston and a brake upper piston; the brake rocker arm is in contact with the brake upper piston, and the brake lower piston drives the first valve assembly through a transmission block (DLB).

3. An auxiliary brake mechanism according to claim 1, wherein: the spool valve includes a spool valve body (HVP), a Check Valve (CV), and a spool valve spring (HVK).

4. An auxiliary brake mechanism according to claim 1, wherein: the drive block (DLB) comprises a first drive block or a second drive block; the first transmission block is connected with a valve bridge (DB) in a sliding mode, the valve bridge (DB) drives a first valve assembly through a ring platform of the first transmission block, and a piston drives the first valve assembly through the top end of the first transmission block under braking; the second transmission block is hinged to a valve bridge (DB), the valve bridge (DB) drives the first valve assembly through a second transmission block input end (DLBI), and the piston drives the first valve assembly through a second transmission block output end (DLBO) under the brake.

5. An auxiliary brake mechanism according to claim 1, wherein: a tappet cup and a push rod are arranged between the cam and the rocker arm.

6. A control method of an auxiliary brake mechanism according to claim 1, characterized in that: the fixing piece (A) is also provided with a brake control cavity (BC), a brake oil release cavity (BT) and a drive control cavity (DC), and the brake oil release cavity (BT) is always in a low-pressure state; in the driving mode, the driving control cavity (DC) and the braking control cavity (BC) are both in a low-pressure state; in the braking mode, the driving control cavity (DC) and the braking control cavity (BC) are both in a high-pressure state; in the cylinder deactivation mode, the drive control chamber (DC) is in a high pressure state and the brake control chamber (BC) is in a low pressure state.