CN102852584A - Continuously variable valve lift system - Google Patents

Abstract

The invention discloses a continuously variable valve lift system, which relates to the field of engine valve design; the continuously variable valve lift system comprises a first rocker arm; the bottom side of a first end of the first rocker arm is in contact with a valve and can push the valve; the bottom side of a second end of the first rocker arm is supported by a hydraulic tappet; the continuously variable valve lift system further comprises a second rocker arm which is used for pushing the first rocker arm and driven by a fixedly arranged driving cam; the second rocker arm is arranged on an eccentric wheel and uses the center of the eccentric wheel as rotation center; the position of the rotation center of the second rocker arm is changed; correspondingly, directions and sizes of a power arm and a resisting arm as well as an angle between the second rocker arm and a horizontal plane are changed; and then the rotation quantity of the first rocker arm is driven to be changed; and finally, the lift of the valve in contact with the first rocker arm is changed; and according to the invention, problems of incomplete performance, complicated structure and expensive manufacturing cost of a lifting engine of the traditional valve lift system are solved.

Description

A Continuously Variable Valve Lift System

technical field

The invention relates to the field of engine valve design, in particular to a continuously variable valve lift system.

Background technique

For a traditional gasoline engine, the valve lift is fixed, and the engine load is adjusted by controlling the throttle opening. Such a control method causes the engine to have a large pumping loss, especially under partial load, the pumping loss is more serious, which will greatly affect the performance of the engine.

Therefore, major international automobile groups have invested a large amount of funds and manpower in the research and development of variable valve lift technology. At present, the continuously variable valve lift technology can change the valve lift according to the operating conditions of the engine, so that the throttle valve is always within a relatively large opening range, which can effectively reduce fuel consumption and emissions, and improve engine power and torque. features. However, among the products currently on the market, one is that the valve lift can be adjusted from two to three levels, but the disadvantage is that it can only partially improve the performance of the engine; the other can realize continuous variable valve lift. But the mechanism is complex and expensive.

Contents of the invention

The purpose of the present invention is to provide a new type of continuously variable valve lift system, which solves the problems of incomplete improvement of engine performance, complex structure and high cost of the current valve lift system.

In order to achieve the purpose of the above invention, the present invention provides a continuously variable valve lift system, comprising:

The first rocker arm, the bottom side of the first end is in contact with the valve and can push the valve, and the bottom side of the second end is supported by a hydraulic tappet;

driving cam, fixed on the camshaft;

a second rocker arm, the drive cam contacts and pushes the first end of the second rocker arm, and the second end of the second rocker arm contacts and pushes the first rocker arm;

The second rocker arm is arranged on the eccentric wheel, with the center of the eccentric wheel as the center of rotation;

When the eccentric wheel rotates, the central position of the eccentric wheel changes, correspondingly changing the power arm and resistance arm of the second rocker arm, and finally changing the lift of the valve in contact with the first rocker arm.

Optionally, in the above device, the position of the rotation center of the second rocker arm changes, and accordingly the direction and size of the power arm and the resistance arm, and the angle between the second rocker arm and the horizontal plane change, Then drive the rotation amount of the first rocker arm to change, and finally change the lift of the valve.

Optionally, in the above device, a drive shaft is arranged parallel to the camshaft at a predetermined distance, and the eccentric wheel is fixed on the drive shaft.

Optionally, in the above device, the rotation range of the eccentric wheel is 0°-90°.

Optionally, in the above-mentioned device, when the center of the eccentric wheel is located vertically below the shaft center of the drive shaft, it is defined as the initial state, at this time, the power arm is the largest, the resistance arm is the smallest, and the valve lift is the smallest .

When the center of the eccentric wheel turns counterclockwise from the initial state to 90°, the rotation center of the second rocker arm rises to the highest point of its working state. At this time, the power arm is the smallest, the resistance arm is the largest, and the valve Maximum lift.

Optionally, in the above device, the first rocker arm is provided with a roller bearing between the first end and the second end for sliding contact with the second rocker arm.

Optionally, in the above device, the contact point between the second end of the second rocker arm and the roller bearing is inwardly concave arc.

Optionally, in the above device, the contact between the first end of the second rocker arm and the driving cam is in an inwardly concave arc shape.

Optionally, in the above-mentioned device, the vertical distance from the rotation center of the second rocker arm to its driving force action line is the power arm, and the driving force is provided by the driving cam;

The vertical distance from the rotation center of the second rocker arm to its resistance action line is the resistance arm, and the resistance is generated by the second rocker arm rotating and pushing the first rocker arm.

The present invention at least has the following technical effects:

1) The present invention uses the rotation of the eccentric wheel to change the position of the rotation center of the second rocker arm, so that the direction and size of the power arm L1 and the resistance arm L2 of the second rocker arm change, and finally change the contact with the first rocker arm. The lift of the valve is small, the structure and principle are simple, and the operation is convenient and fast;

2) Every time the eccentric wheel rotates by an angle in the present invention, the position of the rotation center of the second rocker arm will be changed, thereby changing the valve lift amount, which belongs to stepless regulation, so that the engine performance can be further improved;

3) The rotation angle range of the eccentric wheel in the present invention is only 0°-90°, which can realize the change of the valve lift from the minimum to the maximum, so that the regulation and control efficiency of the system is higher; and the corresponding eccentric wheel rotation control parts are also It can be simplified, easy to manufacture and install, and also improves the reliability of the system;

4) Roller bearings are provided on the first rocker arm of the present invention, so that the friction with the second rocker arm is smaller and the control efficiency is higher; the contact point between the second rocker arm and the first rocker arm and the driving cam They are all designed in a concave arc shape to offset or compensate for the increase or decrease in displacement caused by the rotation of the second rocker arm.

Description of drawings

Fig. 1 is the three-dimensional structure schematic diagram of the present invention;

Fig. 2 is the front view of the present invention;

Fig. 3 is a schematic diagram of the positional relationship of each component when the valve lift amount is respectively minimum and maximum in the present invention;

Fig. 4 is a schematic diagram of the positional relationship before and after the rotation of the eccentric wheel, the moving direction of the center of the eccentric wheel, and the front and rear positional relationship of the second rocking arm moving therewith in the present invention;

Fig. 5 is the schematic diagram of power arm and resistance arm when valve lift amount is minimum in the present invention;

Fig. 6 is a schematic diagram of the power arm and the resistance arm when the valve lift amount is maximum in the present invention;

in,

1-second rocker arm, 2-eccentric wheel, 3-hydraulic tappet, 4-drive cam, 5-first rocker arm, 6-valve, 7-drive shaft, 8-camshaft, 9-roller bearing.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, specific embodiments will be described in detail below with reference to the accompanying drawings.

As shown in Figures 1-6, the embodiment of the present invention provides a continuously variable valve lift system, including:

The first rocker arm 5, the bottom side of its first end is in contact with the valve 6 and can push the valve 6, and the bottom side of the second end is supported by the hydraulic tappet 3, that is, the first rocker arm 5 can rotate around the hydraulic tappet 3.

The driving cam 4 is fixed on the camshaft 8 .

The second rocker arm 1, the drive cam 4 contacts and pushes the first end of the second rocker arm 1, and the second end of the second rocker arm 1 contacts and pushes the first rocker arm 5, that is, the valve The driving force of 6 is provided by the second rocker arm 1.

The second rocker arm 1 is arranged on the eccentric wheel 2 and takes the center of the eccentric wheel 2 as the center of rotation.

When the eccentric wheel 2 rotates, the center position of the eccentric wheel 2 will change, so that the rotation center position of the second rocker arm 1 will change accordingly. The power of the second rocker arm 1 shown in Fig. 4 and Fig. 5 The arm L1 and the resistance arm L2 will also change accordingly, and finally change the lift of the valve 6 in contact with the first rocker arm 5, that is, the valve lift. The structure is simple and the operation is convenient and fast.

In one embodiment of the present invention, a driving shaft 7 may be arranged at a position parallel to the camshaft 8 at a predetermined distance, and the eccentric wheel 2 is fixed on the driving shaft 7 . As shown in part a of Figure 4, during the rotation of the eccentric wheel 2, the change from the solid line to the dotted line in the figure, the change track of the center of the eccentric wheel 2 is arc-shaped, and its rotation angle ranges from 0° to 90°. Simultaneously, the valve lift also realizes the change from min-max as shown in Fig. 3 .

As shown in the solid line part in Fig. 3 and Fig. 5, when the center of the eccentric wheel 2 is located vertically below the shaft center of the drive shaft 7, that is, at point A in part b of Fig. 4, it is defined as the initial state . At this time, the power arm L1 is the largest, the resistance arm L2 is the smallest, and the valve lift is the smallest.

When the center of the eccentric wheel 2 is gradually rotated counterclockwise from the initial state to the direction where the driving cam 4 is located, the center of rotation of the second rocker arm 1 will rotate accordingly and rise along the arc-shaped track, The moving track is shown in the direction of the arrow in part b of FIG. 4 , so that the second rocker arm 1 moves both horizontally and vertically. Because the driving cam 4 is fixed, and the first rocker arm 5 can rotate around the hydraulic tappet 3, it can be known from Fig. 4 and Fig. 5 and common knowledge of mechanics that the above-mentioned movement will inevitably cause the angle between the second rocker arm 1 and the horizontal plane to change , the direction of the power arm L1 will change at this time, and the power arm L1 will gradually become smaller; in addition, the second end of the second rocker arm 1 will push the first rocker arm 5 to rotate clockwise by a certain angle, at this time the resistance arm L2 The direction will change, the resistance arm L2 will gradually become larger, and accordingly the rotation amount of the first rocker arm 5 will also become larger, and finally the lift amount of the valve 6 arranged at the bottom of the first end of the first rocker arm 5 will also gradually increase . As shown in the dotted line part in Fig. 3 and Fig. 6, when the rotation angle of the eccentric wheel 2 is 90°, the rotation center of the second rocker arm 1 rises to the highest point of its working state, that is, in Fig. 4 Point B in part b, at this time, the power arm is the smallest, the resistance arm is the largest, and the valve lift is the largest. Correspondingly, to change the valve lift from large to small, the eccentric wheel 2 can be rotated clockwise, the principle is the same, and the specific process is opposite to the above process, which will not be repeated here.

In the present invention, every time the eccentric wheel 2 rotates by an angle, the position of the rotation center of the second rocker arm 1 will be changed, thereby changing the valve lift amount, that is, the system belongs to stepless control, so that the engine performance can be further improved. In addition, the rotation angle range of the eccentric wheel 2 is only 0°-90°, which can realize the change of the valve lift from the minimum to the maximum, which makes the control efficiency of the system higher; and the corresponding rotation control parts of the eccentric wheel 2 can also be obtained Simplified, easy to manufacture and install, while also improving system reliability.

In an embodiment of the present invention, the first rocker arm 5 may be provided with a roller bearing 9 between the first end and the second end for sliding contact with the second rocker arm 1 so that the first rocker arm 5 The friction between the two rocker arms is smaller, and the control efficiency is higher.

The contact between the second end of the second rocker arm 1 and the roller bearing 9 and the contact between the first end of the second rocker arm 1 and the driving cam 4 are both inwardly concave arcs. To offset or compensate the displacement increase or decrease due to the rotation of the second rocker arm.

In one embodiment of the present invention, the vertical distance from the rotation center of the second rocker arm 1 to its driving force action line is the power arm L1 , and the driving force is provided by the driving cam 4 .

The vertical distance from the rotation center of the second rocker arm 1 to its resistance action line is the resistance arm L2, and the resistance is generated by the second rocker arm 1 rotating and pushing the first rocker arm 5 .

The present invention makes the whole working process of the valve lift amount from the minimum to the maximum as follows:

First, when the engine is running normally, the drive shaft 8 drives the drive cam 4 to rotate, and the drive cam 4 drives the first end of the second rocker arm 1 to make the second rocker arm 1 swing around the eccentric wheel 2, and the second end of the second rocker arm 1 Then drive the first rocker arm 5 to swing around the hydraulic tappet 3, thereby controlling the lift of the valve 6 at the bottom of the first end of the first rocker arm 5.

During stepless regulation, the corresponding driving device drives the eccentric wheel 2 to rotate counterclockwise from the initial state, and every time it rotates an angle, the center position of the eccentric wheel 2 will rise along the arc-shaped track. At this time, the second rocker arm 1 with the center of the eccentric wheel 2 as the center of rotation also rises thereupon, and the second rocker arm 1 is displaced in the horizontal and vertical directions, and the fixed driving cam 4 makes the second rocker arm 1 and The included angle of the horizontal plane changes, so the direction of the power arm L1 changes, and the power arm L1 decreases gradually. Correspondingly, in the process of raising the rotation center of the second rocker arm 1, the second end of the second rocker arm 1 will push the first rocker arm 5 to rotate clockwise by a certain angle. At this time, the direction of the resistance arm L2 will change, and the resistance The arm L2 will gradually become larger, so that the amount of rotation of the first rocker arm 5 becomes larger. Finally, the lift of the valve 6 arranged at the bottom of the first end of the first rocker arm 5 is also gradually increased, thereby achieving the purpose of steplessly regulating the valve lift and improving the performance of the automobile engine. Finally, if the valve lift is to be changed from the maximum to the minimum, then the above working process can be reversed, and will not be repeated here.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (9)

1. A continuously variable valve lift system, characterized in that it comprises: The first rocker arm (5), the bottom side of the first end is in contact with the valve (6) and can push the valve (6), and the bottom side of the second end is supported by the hydraulic tappet (3); Drive cam (4), fixed on the camshaft (8); The second rocker arm (1), the driving cam (4) contacts and pushes the first end of the second rocker arm (1), and the second end of the second rocker arm (1) contacts and pushes the first rocker arm (5); The second rocker arm (1) is arranged on the eccentric wheel (2), with the center of the eccentric wheel (2) as the center of rotation; The eccentric wheel (2) rotates, the center position of the eccentric wheel (2) changes, correspondingly changes the power arm and resistance arm of the second rocker arm (1), and finally changes the same as the first rocker arm (5) ) lift of the valve (6) in contact with each other. 2. The continuously variable valve lift system according to claim 1, characterized in that the position of the rotation center of the second rocker arm (1) changes, corresponding to the direction and size of the power arm and resistance arm . The angle between the second rocker arm (1) and the horizontal plane changes, and then drives the rotation amount of the first rocker arm (5) to change, and finally changes the lift of the valve (6). 3. The continuously variable valve lift system according to claim 1, characterized in that a drive shaft (7) is arranged parallel to the camshaft (8) at a predetermined distance, and the eccentric wheel (2) is fixed on on the drive shaft (7). 4. The continuously variable valve lift system according to claim 3, characterized in that, the rotation range of the eccentric wheel (2) is 0°-90°. 5. The continuously variable valve lift system according to claim 4, characterized in that, When the center of the eccentric wheel (2) is vertically below the shaft center of the drive shaft (7), it is defined as the initial state. At this time, the power arm is the largest, the resistance arm is the smallest, and the valve lift is the smallest. When the center of the eccentric wheel (2) turns counterclockwise from the initial state by 90°, the rotation center of the second rocker arm (1) rises to the highest point of its working state, at this time, the power arm is at its minimum , The resistance arm is the largest, and the valve lift is the largest. 6. The continuously variable valve lift system according to claim 1, characterized in that, the first rocker arm (5) is provided with a roller bearing (9) between the first end and the second end, Used for sliding contact with the second rocker arm (1). 7. The continuously variable valve lift system according to claim 6, characterized in that, the contact point between the second end of the second rocker arm (1) and the roller bearing (9) is inwardly concave arc. 8. The continuously variable valve lift system according to claim 1, characterized in that, the contact point between the first end of the second rocker arm (1) and the driving cam (4) forms an inwardly concave arc shape. 9. The continuously variable valve lift system according to claim 1, characterized in that, The vertical distance from the rotation center of the second rocker arm (1) to its driving force action line is the power arm, and the driving force is provided by the driving cam (4); The vertical distance from the rotation center of the second rocker arm (1) to its resistance action line is the resistance arm, and the resistance is generated by the second rocker arm (1) rotating and pushing the first rocker arm (5).

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