CN106368755A - Variable valve timing mechanism - Google Patents

Abstract

The invention relates to a variable valve distribution mechanism, which includes a valve and a valve transmission assembly. The valve transmission assembly includes a camshaft, a push rod and a rocker arm. At the top, the right end of the rocker arm is against the top of the push rod, and the lower end of the push rod is against the cam of the camshaft. When the rod pushes up the rocker arm to swing counterclockwise, the left end of the rocker arm pushes down the valve to make the valve go down to open the airway. Upward to close the airway, during the up and down movement of the push rod, by changing the stretching amount of the push rod, the upward stroke of the upper end of the push rod is changed, thereby changing the opening and closing position of the valve and the length of the stroke. The invention can steplessly regulate the valve lift, make the gas distribution phase optimal in real time, and significantly improve the performance of the engine.

Description

variable valve train

technical field

The invention relates to an engine valve gas distribution mechanism, in particular to a valve gas distribution mechanism with stepless adjustable valve lift.

Background technique

The function of the gas distribution mechanism is to open and close the intake and exhaust valves regularly according to the requirements of the engine firing sequence and the working cycle of each cylinder, so that fresh gas can enter the cylinder in time, and exhaust gas can be discharged from the cylinder in time. Ideally, it is hoped that the amount of gas entering and exiting the cylinder just meets the needs of the real-time working conditions of the engine (including load, operating speed, etc.), so that the engine can perform at its best.

However, the reality is that the traditional valve train consists of camshafts, tappets, pushrods, rocker arms, valves and other parts. The opening of the valves is determined by the lift of the cam on the camshaft, which cannot be adjusted or continuously adjusted. After the engine is manufactured, the valve timing and valve lift are fixed, which cannot meet the needs of the engine for intake and exhaust under different working conditions. Traditionally, engine designers have made compromises when considering cam profiles, such as taking care of high speeds as well as low speeds. However, this kind of compromise has limited the performance of the engine to some extent, including that the output cannot meet the requirements at low speeds, and the power cannot meet the needs at high speeds, which is far from meeting the requirements of current vehicle engines.

It can be seen that the valve train affects the operating conditions of the engine to a large extent. Each operating condition of the engine has its own corresponding optimal operating parameters. For changing working conditions, especially when driving in the city, if it can be adjusted constantly, it will greatly improve the performance of the engine, thereby achieving energy-saving and economical effects. Therefore, people hope to have such an engine, no matter what working conditions it needs to be in, the valve train can provide the corresponding optimal valve timing.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides a variable valve valve mechanism, which can steplessly adjust the valve lift within a certain range, so that the valve timing can be optimized in real time, and the engine can be in the best position in real time. The working condition can significantly improve the performance of the engine.

Main technical scheme of the present invention has:

A variable valve distribution mechanism, including a valve and a valve transmission assembly, the valve transmission assembly includes a camshaft, a push rod and a rocker arm, the middle part of the rocker arm is hinged on the cylinder head, and the left end of the rocker arm is against the At the top of the valve, the right end of the rocker arm is against the top of the push rod, and the lower end of the push rod is against the cam of the camshaft. The push rod is an automatically telescopic push rod, working When the camshaft rotates, the cam drives the push rod to move up and down. When the push rod pushes the rocker arm up to swing counterclockwise, the left end of the rocker arm pushes down the valve to make it The valve moves downward to open the airway. When the push rod falls and drives the rocker arm to swing clockwise, the valve moves upward to close the airway as the left end of the rocker arm rises. When the push rod moves up and down In this process, by changing the telescoping amount of the push rod, the upward stroke of the upper end of the push rod is changed, thereby changing the opening and closing position and stroke length of the valve.

The push rod is preferably a push rod on which an electro-hydraulic device is added.

The push rod may be a two-way electronically controlled hydraulic cylinder.

The push rod may include a single-rod hydraulic cylinder and a solenoid valve for controlling the reversing of the single-rod hydraulic cylinder. The rod extension end of the single-rod hydraulic cylinder is connected to the right end of the rocker arm. The cylinder barrel of the hydraulic cylinder is supported on the cam.

The solenoid valve is electrically connected to the valve lift control output signal end of the engine electronic control unit.

The right end of the rocking arm can be connected with an adjustment screw and fixed by an adjustment nut, and the top of the push rod can be against the adjustment screw.

The top of the push rod can be connected with the head of the adjusting screw in a swinging fit.

A movement limiting structure may be provided in the circumferential direction of the push rod.

The cylinder head is provided with a section of cylindrical air passage hole that slides with the head of the valve, and the head of the valve is inserted into the cylindrical air passage hole from top to bottom. The lower end of the channel hole communicates with the combustion chamber of the cylinder.

The outer diameter of the valve head and/or the side wall of the cylindrical airway hole may be provided with a sealing structure in the circumferential direction.

The beneficial effects of the present invention are:

The valve mechanism of the present invention is used in the automobile engine, and can change the opening and closing time and the lift of the valve in real time and steplessly according to the operating conditions of the automobile, so that the performance of the engine can be significantly improved.

Since the push rod is a push rod with an electronically controlled hydraulic device installed on it, the expansion and contraction of the push rod is realized through electronic control, so it is very easy to realize the programmed control of gas distribution, and the real-time performance is good, which is convenient to incorporate into the engine electronic control system. unit, combined with load and speed detection to achieve closed-loop control.

The invention significantly improves the power performance and fuel economy of the engine through the precise control of the valve timing, and can make the engine Maintain the highest operating efficiency, not only high fuel utilization, but also reduce unnecessary exhaust emissions.

The present invention realizes the stepless adjustment of valve opening and closing time and lift through the same set of mechanism, has simple structure and is easy to realize, even if it is relatively easy to transform on the basis of the existing valve mechanism.

The air distribution mechanism of the present invention can be used for independent adjustment of each cylinder, and even a certain cylinder can be closed when needed, so that the engine can maintain high efficiency when working in a light load state.

Description of drawings

Fig. 1 is the structural representation of an embodiment of the present invention;

Fig. 2 is a comparison table of valve variation ranges under different push rod lengths according to the present invention.

detailed description

The invention discloses a variable valve distribution mechanism, as shown in Figures 1 and 2, comprising a valve 1 and a valve drive assembly, the valve drive assembly includes a camshaft, a push rod 3 and a rocker arm 4, the rocker arm The middle part of the rocker arm is hinged to form a lever through the rocker shaft, and the rocker shaft is fixed relative to the cylinder head 2. The left end of the rocker arm is against the top of the valve, and the right end of the rocker arm is against the top of the push rod. The lower end of the push rod is against the cam 5 of the camshaft, and the top of the push rod moves up and down, driving the rocking arm to swing around the rocker shaft, and then driving the valve to move up and down. The push rod is an automatically retractable push rod (VPR, Variable Push Rod). When working, the camshaft rotates, and the cam drives the push rod to move up and down. When it swings counterclockwise, the left end of the rocker arm pushes down the valve so that the valve goes down to open the airway. When the push rod falls and drives the rocker arm to swing clockwise, the valve follows the The left end of the rocker arm is lifted up to close the air passage. During the up and down movement of the push rod, by changing the telescopic amount of the push rod, the upward stroke of the upper end of the push rod is changed, thereby changing the opening and closing of the valve. location and length of trip. The automatic retractable pushrod enables the engine to have a proper valve timing in a wider speed range and load range, which improves the performance of the engine to a large extent. The variable valve distribution mechanism is used in automobile engines, and can simultaneously and in real time and steplessly change the valve opening and closing timing and lift according to the operating conditions of the automobile, so that the engine can always maintain a high working efficiency and power ratio. As a result, the performance of the engine is significantly improved, and the fuel utilization rate can be improved and the exhaust emission can be reduced to a certain extent.

The push rod is preferably a push rod equipped with an electronically controlled hydraulic device, for example, a two-way electronically controlled hydraulic cylinder can be used. Specifically, the push rod may include a single-rod hydraulic cylinder and a solenoid valve for controlling the reversing of the single-rod hydraulic cylinder. The cylinder barrel of the single rod hydraulic cylinder is supported on the cam.

The solenoid valve is electrically connected to the valve lift control output signal end of the engine electronic control unit. Said speed sensor and load sensor can also be connected. When the engine is running, the engine electronic control unit can judge whether it is necessary to change the valve switch time and valve lift according to the signals of each sensor. The action of the solenoid valve controls the expansion or contraction and the amount of expansion and contraction of the push rod. The pushrod lengthens or shortens, achieving an effect similar to changing the profile of a cam, improving engine performance.

The right end of the rocking arm can be connected with an adjusting screw 6 and fixed by an adjusting nut, and the top of the push rod can be against the adjusting screw. Further, the head of the adjustment screw faces downward, and a concave curved surface is provided on it, and the top of the push rod is against the curved surface, or, the top of the push rod is provided with a concave curved surface, so The head of the adjustment screw abuts against the curved surface of the push rod to realize the swing fit connection with the head of the adjustment screw. The relative position of the top of the push rod and the right end of the rocking arm can be fine-tuned by changing the position of the adjusting screw.

A movement limiting structure may be provided in the circumferential direction of the push rod to ensure that the axial position of the push rod remains unchanged. For example, it is similar to the tappet structure of the traditional gas distribution mechanism, or it can also be realized by setting up and down the guide key and groove structure extending up and down on the lower part of the push rod and its surrounding structural members.

The air cylinder head is provided with a section of cylindrical airway hole which slides with the head of the valve, and the head of the valve is inserted into the cylindrical airway hole from top to bottom. The lower end of the air passage hole communicates with the combustion chamber of the cylinder. In the present invention, the periphery of the air valve is changed into a straight column-type side wall 7 (the side wall of the cylindrical airway hole), which can ensure that the air valve does not leak when the length of the push rod changes.

The outer diameter of the valve head and/or the side wall of the cylindrical airway hole may be provided with a sealing structure in the circumferential direction to increase the airtightness.

Fig. 2 is the comparison of the highest position and the lowest position of the valve under different push rod lengths of the present invention. After the push rod is elongated, the highest and lowest positions of the valve have a certain range of downward movement. The area is significantly larger, which can be used in high-speed engine conditions to improve its power performance. In fact, because the telescopic and telescopic amount of the push rod can be adjusted at any time, not only the highest position and the lowest position of the valve can be changed in real time, but also the distance between the highest position and the lowest position (that is, the valve stroke) can be changed at any time, thus greatly improving The flexibility of valve opening adjustment is improved.

The invention can simultaneously realize the stepless control of the valve opening and closing time and lift within a certain range through a set of mechanisms, so it can better adapt to various working conditions of the engine.

The term "up, down, left, and right" in the present invention is for the convenience of expressing the relative position of each part, and does not constitute a limitation on the specific orientation of the specific structure of the present invention.

Claims (10)

1. A variable valve distribution mechanism, comprising a valve and a valve drive assembly, the valve drive assembly comprising a camshaft, a push rod and a rocker arm, the middle part of the rocker arm is hinged on the cylinder head, and the rocker arm The left end is against the top of the valve, the right end of the rocker arm is against the top of the push rod, and the lower end of the push rod is against the cam of the camshaft. It is characterized in that: the push rod can Automatic telescopic push rod, when working, the camshaft rotates, and the cam drives the push rod to move up and down. When the push rod pushes the rocker arm up to make it swing counterclockwise, the left end of the rocker arm Push the valve down to open the airway downward. When the push rod falls and drives the rocker arm to swing clockwise, the valve moves upward to close the airway as the left end of the rocker arm rises. During the upward and downward movement of the push rod, by changing the stretching amount of the push rod, the upward stroke of the upper end of the push rod is changed, thereby changing the opening and closing position and stroke length of the valve. 2. The variable valve distribution mechanism according to claim 1, characterized in that: said push rod is a push rod on which an electronically controlled hydraulic device is installed. 3. The variable valve distribution mechanism according to claim 2, characterized in that: said push rod is a two-way electronically controlled hydraulic cylinder. 4. The variable valve distribution mechanism according to claim 3, characterized in that: said push rod comprises a single-rod hydraulic cylinder and a solenoid valve for controlling the reversing of said single-rod hydraulic cylinder, and said single-rod hydraulic cylinder The end of the cylinder rod is connected to the right end of the rocker arm, and the cylinder barrel of the single-rod hydraulic cylinder is supported on the cam. 5 . The variable valve distribution mechanism according to claim 4 , wherein the solenoid valve is electrically connected to the valve lift control output signal end of the engine electronic control unit. 6 . 6. The variable valve distribution mechanism according to claim 5, wherein an adjusting screw is connected to the right end of the rocker arm and fixed by an adjusting nut, and the top of the push rod abuts against the adjusting screw . 7. The variable valve distribution mechanism according to claim 6, characterized in that: the top of the push rod is connected to the head of the adjusting screw in a swinging fit. 8 . The variable valve distribution mechanism according to claim 7 , wherein a movement limiting structure is provided in the circumferential direction of the push rod. 9 . 9. The variable valve distribution mechanism according to claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that: the cylinder head is provided with a section that slides with the head of the valve A matching cylindrical air passage hole, the head of the valve is inserted into the cylindrical air passage hole from top to bottom, and the lower end of the cylindrical air passage hole communicates with the combustion chamber of the cylinder. 10. The variable valve distribution mechanism according to claim 9, characterized in that: the outer diameter of the head of the valve and/or the circumferential direction of the side wall of the cylindrical air passage hole is provided with a sealing structure.