CN104895634A - Continuously variable timing device - Google Patents

Abstract

The invention relates to a continuously variable timing device, which comprises a hollow camshaft, a built-in camshaft, and two intake cams; the built-in camshaft is installed in the hollow cam through a bearing; the No. 1 intake cam is composed of an adjustable cam and a fixed The adjustable intake cam is installed on the built-in camshaft through the second fixed pin, and the fixed cam is installed on the hollow cam; the No. 2 intake cam is composed of another adjustable cam and another fixed cam; the other The adjustable intake cam is installed on the built-in camshaft through the first fixed pin, and the other fixed cam is installed on the hollow cam. Compared with the traditional 0-30 degree valve continuously adjustable adjustment mechanism, the present invention has a larger adjustable range and stronger reliability; compared with the current most advanced Toyota VVL system, the adjustment mechanism is simplified and the structure is simple. Occupying a small space, it can be applied to small-displacement engines, greatly reduces production costs, and is easy to popularize and use.

Description

A continuously variable timing device

technical field

The invention relates to a variable timing device for an internal combustion engine, in particular to a combined camshaft variable timing device.

Background technique

In recent decades, many countries, engine manufacturers, and scientific research institutions have invested a lot of manpower and material resources in the research and development of new technologies based on the requirements of improving the power, economy and reducing pollution of automobile engines. At present, some of these new technologies and methods have been applied to internal combustion engines, and some are in the stage of development and perfection. In the current use of internal combustion engines, the closing & opening of the valve is part of the working state of the internal combustion engine. In order to achieve the optimal valve control mode, the designer expects to be able to open or close the intake and exhaust of the engine according to different needs. valve. Engine variable valve timing technology (VVT, Variavle Valve Timing) is one of the new technologies that have been gradually applied to modern cars in recent years. Adjustment can increase the charge coefficient, thereby increasing engine power, optimizing torque curve, improving product power, and reducing fuel consumption. The advantages brought by variable gas distribution technology are obvious, and this technology will gradually become the standard of advanced engines equipped. With the popularity of this technology, it is now equipped on most mainstream engines, and engines that are not equipped with this technology will face obsolete in most fields.

Usually the valve is driven by the crankshaft of the engine through the camshaft, and the valve timing depends on the rotation angle of the camshaft. In ordinary engines, the opening and closing time of the intake valve and exhaust valve is fixed. This fixed timing is difficult to take into account the working requirements of the engine at different speeds. Variable valve timing is the solution to this problem. A paradoxical technology. When the engine is running, we need to let more fresh air enter the combustion chamber so that the exhaust gas can be discharged from the combustion chamber as much as possible. The best solution is to let the intake valve open in advance and the exhaust valve to close later. In this way, between the intake stroke and the exhaust stroke, the intake valve and the exhaust valve will open at the same time, and the overlap between the intake and exhaust valves is called the valve overlap angle. When the engine is at different speeds, the requirements for the valve overlap angle are also different. There is no fixed valve stack angle setting that can make the engine output perfectly at high speeds. If there is no variable valve timing technology, the engine can only choose the optimal fixed valve stack according to the needs of its matching model. horn. For example, racing engines generally use a smaller valve stack angle to facilitate power output at high speeds. Ordinary civilian cars use moderate valve stacking angles, taking into account high-speed and low-speed power output at the same time, but will lose a lot of power at low and high speeds. The variable valve timing technology is to solve this contradiction by realizing the variable valve superposition angle through technical means.

Adopting the variable valve timing technology, the power and torque output of the engine will be more linear, while taking into account the power output of high and low speeds, so that the speed of the engine can be designed to be higher, thus obtaining more power output; Variable valve timing technology, the engine can increase the torque output at low speed, greatly enhancing the driving flexibility, while the engine adopts variable valve timing technology to obtain the above benefits, there is no negative effect, in other words, there is no impact on The working intensity of the engine puts forward higher requirements. In the entire field of variable gas distribution technology, it adjusts the phase of the camshaft according to the needs of the engine through hydraulic and gear transmission mechanisms, and realizes dynamic adjustment of valve timing. A set of hydraulic devices and solenoid valves are required, and the control hydraulic cylinder is connected to the high-pressure oil circuit, then the piston will move in the direction of the camshaft, and then the rotation angle of the camshaft will be advanced. Higher performance variable valve timing VVT system The phase angle can be continuously variable, and the valve phase can be adjusted linearly between 0°-30° according to the speed. The disadvantage is that the reliability of the hydraulic system is easily disturbed by pollutants and the duration of valve opening and closing cannot be changed.

Currently, Toyota's VVTL-I is the most advanced VVT system in the world. Its powerful functions include: continuously variable valve timing, variable valve stroke and valve opening duration in two stages, and variable intake and exhaust. This variable valve timing system also calculates the appropriate valve timing through the engine management system according to the engine speed, acceleration, uphill, downhill and other parameters, and controls it through a hydraulic mechanism arranged at the end of the camshaft . In addition, its phase angle can be continuously variable in the range of 0-60 degrees. The valve timing is thus perfectly matched to the work of the engine. Toyota's system uses a set of rocker arms that sit between the intake valves (or exhaust valves). It also has two differently shaped cams to drive the rocker arm, the cross-sections of which have different shapes, one with a longer valve opening time (for high RPMs) and the other with a shorter valve opening time (for low at speed). At low speed, the low-speed cam drives the rocker arm to move through rolling bearings (in order to reduce frictional resistance). At high RPM, there is not enough clearance between this cam and the hydraulic jack below to directly drive the rocker arm. When the speed increases to the limit, the slider is pushed into the gap of the hydraulic ejector rod under the action of hydraulic pressure. The high-speed cam starts to work effectively. Driven by the high-speed cam, the valve opening duration is longer, and the stroke is longer at this time (just like Honda's VTEC, the valve opening stroke and opening duration are determined by the shape of the camshaft). However, its shortcomings are also very obvious: the structure is also extremely complex, the cost is high, and a large amount of cost in the manufacturing process can ensure the continuous operation of the entire system.

Contents of the invention

The technical problem to be solved by the present invention is to propose a continuously variable timing device, which uses a combined camshaft to solve the problem that the reliability of the current hydraulic mechanism control is relatively poor, and the high-performance continuously variable timing device has a complex mechanism and high cost The problem.

The technical solution adopted in the present invention is: a continuously variable timing device, including a hollow camshaft, a built-in camshaft, a No. 1 intake valve cam, and a No. 2 intake valve cam; the built-in camshaft is installed through a bearing In the hollow cam; the No. 1 intake cam is composed of an adjustable cam and a fixed cam; the adjustable intake cam is installed on the built-in camshaft through the second fixed pin, and the fixed cam is installed on the hollow cam ; The No. 2 intake cam is composed of another adjustable cam and another fixed cam; the other adjustable intake cam is installed on the built-in camshaft through the first fixed pin, and the other fixed cam Mounted on hollow cam.

Furthermore, the built-in camshaft and the hollow camshaft according to the present invention rotate at a relative angle of 0-70 degrees. The built-in camshaft of the present invention is provided with a worm gear, which can be driven by the worm to rotate with the hollow camshaft at a relative angle of 0-70 degrees.

Furthermore, the clockwise movement of the worm in the present invention drives the turbine to rotate, and the turbine drives the built-in camshaft to rotate clockwise; the counterclockwise movement of the worm drives the turbine to rotate, and the turbine drives the built-in camshaft to rotate counterclockwise.

The beneficial effects of the present invention are: compared with the traditional 0-30 degree continuously adjustable valve adjustment mechanism, its adjustable range is larger and its reliability is stronger; compared with the current most advanced Toyota VVL system, the present invention simplifies The adjusting mechanism has a simple structure and takes up little space, can be applied to engines with small displacements, greatly reduces production costs, and is easy to popularize and use.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a structural representation of the present invention;

Figure 1-1 is a partial enlarged view of I in Figure 1;

Figure 2 is a schematic diagram of the opening timing of the intake valve and exhaust valve during cold start and idling conditions;

Figure 3 is a schematic diagram of the opening timing of the intake valve and exhaust valve when the engine speed is at medium and high speed (>1300rpm);

Figure 4 is a schematic diagram of the opening time of the intake valve and exhaust valve when the engine speed is at high speed (>3600r/min);

Fig. 5 is a schematic structural view of another embodiment of the present invention;

In the figure: 1-hollow camshaft; 2-No. 1 intake cam; 21-adjustable cam; 22-fixed cam; 3-No. 2 intake cam; 31-another adjustable cam; 32-another Fixed cam; 4-built-in camshaft; 5-first fixed pin; 6-second fixed pin; 7-turbine; 8-worm; CRA-camshaft angle; TDC-engine top dead center; H-valve lift.

Detailed ways

The present invention will now be described in further detail in conjunction with the accompanying drawings and preferred embodiments. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

As shown in Figure 1 and Figure 1-1, a continuously variable timing device includes a hollow camshaft 1, a built-in camshaft 4, and the No. 1 intake cam 2, and the No. 1 intake cam 2 is controlled by an adjustable The cam 21 and the fixed cam 22 are composed. The adjustable intake cam 21 is installed on the built-in camshaft 4 through the second fixed pin 6 and the No. 2 intake valve cam 3 is installed on the built-in camshaft 4 through the first fixed pin 5. The fixed cam 22 is installed on the hollow cam 1 On the No. 2 intake valve cam 3, the built-in camshaft 4 is installed in the hollow cam 1 through a bearing; The relative angle is 0-70 degrees of rotation.

As shown in Figure 5, the No. 2 intake valve cam 3 of the continuously variable timing device can also be made into a combined cam structure, which is composed of another adjustable cam 31 and another fixed cam 32, and the other adjustable Cam 31 is built-in camshaft 4 by fixed pin, and another fixed cam 32 is installed on the hollow cam 1.

Taking the continuously variable timing device applied to the engine intake valve as an example, its working process is briefly described:

The performance of the engine can be improved by using a variable valve timing mechanism. Different engine speeds require different valve timings. When the engine speed changes, the effect of using the airflow inertia to increase the intake and promote the exhaust during the late valve closing period will be different because the intake flow rate and the exhaust flow rate during the forced exhaust period will also change.

As shown in Figure 2, when the engine is in the cold start and idle condition of less than 1300rpm, the worm 8 moves clockwise to drive the turbine 7 to rotate, and the turbine 7 drives the built-in camshaft 4 to rotate clockwise, so that the camshaft 4 and When the hollow camshaft 1 rotates clockwise through a certain angle θ, the early opening angle of the intake valve becomes smaller, the overlap angle between the intake valve and the exhaust valve is the smallest under cold start and idling conditions, the required fuel concentration is the lowest, and the combustion is stable The performance is good, and the engine runs smoothly at low speed; since the engine usually has 3 cylinders or 4 cylinders, EX1 in Figure 2 indicates the first exhaust valve of a certain cylinder of the engine, and EX2 indicates the second exhaust valve of a certain cylinder of the engine ; IN1 represents the first intake valve of a certain cylinder of the engine, and IN2 represents the second intake valve of a certain cylinder of the engine.

As shown in Figure 3, when the engine speed is higher than 1300r/min, the worm 8 moves counterclockwise at this time, driving the turbine 7 to rotate, and the turbine 7 drives the built-in camshaft 4 to rotate counterclockwise, so that the camshaft 4 and the hollow camshaft 1 Turn counterclockwise through a certain angle θ, the early opening angle of the intake valve becomes larger, the overlapping angle of the intake and exhaust valves becomes larger, the exhaust gas discharge rate increases, and the volumetric efficiency and torque value are improved. EX1 in Figure 3 represents the first exhaust valve of a certain cylinder of the engine, EX2 represents the second exhaust valve of a certain cylinder of the engine; IN1 represents the first intake valve of a certain cylinder of the engine, and IN2 represents the second intake valve of a certain cylinder of the engine Door.

As shown in Figure 4, when the engine speed is higher than 3600r/min, the worm 8 drives the turbine 7 to reset, the adjustment work is completed, the intake valve returns to the non-advance position, and the angle of late opening and closing of the intake valve increases. The valve overlap angle is relatively small, and the inertial energy of the gas can be used to increase the intake air volume and reduce the residual exhaust gas volume, so that the engine's ventilation process can be perfected and the power value can be increased. EX1 in Figure 4 represents the first exhaust valve of a certain cylinder of the engine, EX2 represents the second exhaust valve of a certain cylinder of the engine; IN1 represents the first intake valve of a certain cylinder of the engine, and IN2 represents the second intake valve of a certain cylinder of the engine Door.

The characteristic of the variable valve timing mechanism is that it only changes the opening and closing time of the intake valve and the intake air volume, and the valve phase angle value remains unchanged (time translation—that is, early opening and early closing; late opening and late closing), The size of the intake valve lift is not changed.

According to different engines, the present invention can be respectively applied to the four structures of the current continuously variable VVT of the engine: only the intake cam phase is adjusted; only the exhaust phase is adjusted; the intake and exhaust phases are simultaneously adjusted; the intake and exhaust double independent phases are adjusted.

What is described in the above description is only the specific implementation of the present invention, and various illustrations do not limit the essence of the present invention. Those of ordinary skill in the art can modify or modify the previous specific implementation after reading the description. variations without departing from the spirit and scope of the invention.

Claims (5)

1. A continuously variable timing device, characterized in that: comprising a hollow camshaft (1), a built-in camshaft (4), No. 1 intake valve cam (2), and No. 2 intake valve cam (3); The built-in camshaft (4) is installed in the hollow cam (1) through a bearing; the No. 1 intake cam (2) is composed of an adjustable cam (21) and a fixed cam (22); the adjustable The adjustable intake cam (21) is installed on the built-in camshaft (4) through the second fixed pin (6), and the fixed cam (22) is installed on the hollow cam (1); the No. 2 intake valve cam ( 3) It consists of another adjustable cam (31) and another fixed cam (32); the other adjustable intake cam (31) is installed on the built-in camshaft (4) through the first fixed pin (5) ), another fixed cam (32) is installed on the hollow cam (1). 2. A continuously variable timing device according to claim 1, characterized in that: the built-in camshaft (4) and the hollow camshaft (1) rotate at a relative angle of 0-70 degrees. 3. A continuously variable timing device according to claim 2, characterized in that: said built-in camshaft (4) is provided with a worm gear (7), driven by the worm (8) to achieve a hollow The camshaft (1) rotates at a relative angle of 0 to 70 degrees. 4. A continuously variable timing device as claimed in claim 3, characterized in that: the worm (8) moves clockwise to drive the turbine (7) to rotate, and the turbine (7) drives the built-in camshaft ( 4) Turn clockwise. 5. A continuously variable timing device as claimed in claim 3, characterized in that: the worm (8) moves counterclockwise to drive the turbine (7) to rotate, and the turbine (7) drives the built-in camshaft ( 4) Turn counterclockwise.