KR20030049217A - variation system of valve spring stiffness for automotive vehicles - Google Patents

Abstract

PURPOSE: A variation system of valve spring stiffness for vehicles is provided to suppress the loss of engine driving torque and to improve fuel efficiency by varying the stiffness of a valve spring depending on the operating condition of an engine. CONSTITUTION: A variation system of valve spring stiffness for vehicles comprises an intake/exhaust valve, a valve spring applying restorative force in the operation of the intake/exhaust valve, a retainer assembly supporting the upper end of the valve spring, a tappet placed on the upper end of the intake/exhaust valve, a cam mounted on a cam shaft and promoting the opening of the intake/exhaust valve, a mounting member(26) changing the mounting length of the valve spring, an actuator(30) promoting the operation of the mounting member, and a control unit(34) controlling the operation of the actuator.

Description

Variation system of valve spring stiffness for automotive vehicles

The present invention relates to a valve spring stiffness variable device of the engine, and more particularly, by varying the rigidity of the valve spring in accordance with the operating speed of the engine to reduce fuel losses caused by the valve train system to improve the fuel economy. It relates to a valve spring stiffness variable device of the engine that allows.

In general, the engine of the vehicle is a device that uses the kinetic energy generated by injecting and combusting a mixture of a mixture of fuel and air into the combustion chamber formed by the cylinder head cover and the cylinder block to drive the vehicle. In the case of the same engine, fuel economy is an important factor in determining the performance of the engine, accordingly, the vehicle manufacturers are making a lot of efforts to improve the fuel efficiency in the design and manufacture of the engine.

On the other hand, the main methods for improving the fuel efficiency of the engine is to reduce the fuel consumption rate by efficiently performing combustion generated in the combustion chamber, and to improve the fuel efficiency of the engine by reducing the driving friction loss in the driving of the engine. have.

Among them, the main factors that determine the frictional loss of the engine include friction loss by the crank train, friction loss by the valve train, and driving friction loss by other auxiliary equipment. Friction losses are typically known to occupy approximately one third of the friction loss of the entire engine when the engine is operated in the region of low running speed (approximately 2000 rpm).

Therefore, if the driving torque in the valve train system of the engine is reduced to reduce the friction loss, the fuel economy of the engine can be improved.

On the other hand, the configuration of the valve train system of the intake / exhaust valve in the general engine is installed on the intake / exhaust passage 12 formed in the cylinder head 10, as shown in FIG. An exhaust valve 14, a valve spring 16 fitted to the outer circumference of the valve stem 14a of the intake / exhaust valve 14, a retainer assembly 18 for holding and fixing an upper end of the valve spring 16; And a tappet 20 seated on the upper end of the valve stem 14a, and a cam 24 mounted on the camshaft 22 on the upper part of the tappet 20.

Here, the lower end of the valve spring 16 is supported on the valve seat 10a on the cylinder head 10, and the upper end is supported by the retainer assembly 18.

The camshaft 22 is connected via a crankshaft and a timing device (timing belt or timing chain or timing gear) so as to rotate in conjunction with the rotation of the crankshaft (not shown) of the engine.

Therefore, when the engine is operated, the crankshaft is rotated, the camshaft 22 connected through the crankshaft and the timing device is rotated, and the cam 24 provided on the camshaft 22 is rotated so that its profile ; The tappet 20 is periodically pressurized according to the contour, while the valve stem 14a of the intake / exhaust valve 14 periodically presses the valve spring 16 according to the periodic pressurization of the tappet 20. The intake / exhaust passage 12 is opened and closed by repeatedly descending and raising while pressurizing.

On the other hand, in the valve train system of the engine, the valve spring 16 should be able to stably maintain the dynamic behavior of the valve system up to the maximum allowable operating speed of the engine, for this purpose, the valve spring 16 is the mounting load thereof The stiffness and stiffness are each designed to match the maximum permitted operating speed of the engine.

Here, the maximum allowable driving speed is in the range of about 7000rpm in the case of a gasoline engine and 5200rpm in the case of a diesel engine, but under normal driving conditions, the operating speed of the engine does not significantly exceed the maximum allowable driving speed of the engine, The range is approximately 2000 to 3000 rpm for diesel engines and approximately 1000 to 2000 rpm for diesel engines.

However, as the operating speed of the engine increases, the magnitude of the inertia force due to the inertia mass in the valve train system becomes proportional to the product of the square of the acceleration of the valve and the inertia mass of the valve. The rigidity of the valve spring 16 Since the design is designed to overcome the magnitude of the inertia force of the valve system at the maximum allowable operating speed, the stiffness of the valve spring 16 under normal driving conditions is required to achieve the required valve spring ( It is sufficient to be smaller than the stiffness of 16).

That is, the valve spring 16 is designed to have rigidity in consideration of the maximum allowable driving speed of the engine, even though the valve spring 16 may be designed to have its rigidity in consideration of the normal operating speed of the engine. When operating under low speed operating conditions, the torque for driving the valve train system is much larger than necessary, which is disadvantageous in terms of fuel efficiency.

Accordingly, the present invention has been made in view of the above, and by varying the stiffness of the valve spring according to the operating conditions of the engine, it is possible to reduce the driving torque loss of the engine, which is unnecessarily consumed in the low speed operating region. It is an object of the present invention to provide a valve spring stiffness variable device of the engine that can improve the fuel economy.

The present invention for achieving the above object, the inlet / exhaust valve is installed on the intake / exhaust valve of the cylinder head to control the opening and closing of the valve, the valve spring for imparting a restoring force during operation of the intake / exhaust valve, A retainer assembly for holding an upper end of the valve spring, a tappet seated on an upper end of the intake / exhaust valve, and a cam mounted on a cam shaft at an upper part of the tappet to support opening and closing of the intake / exhaust valve. In a valve train system, the valve spring includes a mounting member for varying its mounting length in accordance with an operating speed of the engine, an actuator for driving the mounting member, and a control unit for controlling the operation of the actuator. It is characterized in that it is adapted to change its mounting stiffness by means of means.

1 is a cross-sectional view showing a valve train system of a conventional automobile engine.

Figure 2 is a cross-sectional view showing a valve train system of an automotive engine with a valve spring stiffness variable device according to the present invention.

3 is a schematic view showing a specific configuration of the valve spring stiffness variable device shown in FIG.

Figure 4 is a perspective view showing the configuration of the mounting member and the pressing member for operating it shown in Figures 2 to 3, respectively.

5 is a cross-sectional view showing the operating state of the mounting member during the medium speed operation of the engine.

6 is a cross-sectional view showing an operating state of the mounting member at high speed of the engine;

<Description of Symbols for Main Parts of Drawings>

10-cylinder head 12-intake / exhaust passage

14-intake / exhaust valve 16-valve spring

18-Retainer Assembly 20-Tappet

22-camshaft24-cam

26-mounting member 28-pressure member

30-actuator 32-switching valve

34-control unit 36-vehicle speed sensor

38-height moving plate 40-height moving plate

42-hydraulic pump 44-position sensor

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view illustrating a valve train system of an automotive engine having a valve spring stiffness variable device according to the present invention, and FIG. 3 is a schematic view showing a specific configuration of the valve spring stiffness variable device shown in FIG. 2 is a perspective view showing the configuration of the mounting member shown in Figures 2 and 3 and the pressing member for operating the same, the same reference portion as in Figure 1 showing a valve train system of a conventional engine for a detailed description of the invention The same reference numerals are given together.

The present invention is to allow the rigidity of the valve spring in the valve train system of the engine to be changed according to the operating speed of the engine bar, the valve train system of the engine, as shown in Figure 2, the cylinder head (10) Intake / exhaust valve 14 provided on the intake / exhaust passage 12 formed in the control panel 12 and controlling the opening and closing thereof, and a valve spring 16 fitted to the outer circumference of the valve stem 14a of the intake / exhaust valve 14. ), A retainer assembly 18 holding the upper end of the valve spring 16 fixed thereto, a tappet 20 seated on the upper end of the valve stem 14a, and a camshaft 22 on the upper end of the tappet 20. And a cam 24 mounted on it.

Here, the valve spring 16 is provided with a variable means for varying its mounting length in accordance with the operating speed of the engine to vary the spring stiffness, which is shown in FIGS. As described above, the mounting member 26 is installed to face up and down on the bottom of the valve spring 16 so as to vary the mounting height of the valve spring 16 by varying the overall height according to the adhesion distance, A pressurizing member 28 that applies an operating force to the mounting member 26 to vary its overall height, an actuator 30 that applies an actuation force to the pressing member 28 to support the operation of the mounting member 26, and the actuator. A switching valve 32 for adjusting the operation amount of the 30, a control unit 34 for controlling the operation of the switching valve 32, and a vehicle speed detection for inputting a vehicle speed of the vehicle being driven to the control unit 34 Consisting of sensors 36 All.

In addition, the mounting member 26 is in contact with the bottom surface of the height direction moving plate 38 and the height direction moving plate 38 which is in contact with the bottom portion of the valve spring 16, the bottom surface is the cylinder It is composed of a longitudinal moving plate 40 facing the head 10, the bottom surface of the height moving plate 38 and the upper surface of the longitudinal moving plate 40 inclined at a predetermined angle, respectively The inclined surfaces 38a and 40a are formed, and the pressing surface 40b is inclined at a predetermined angle along the longitudinal direction from one side of the longitudinal moving plate 40.

In addition, the height moving plate 38 is provided with a through hole 38b for accommodating the valve stem 14a of the intake / exhaust valve 14, and the length moving plate 40 has an intake / exhaust air. A long hole 40c is formed to accommodate the valve stem 14a of the valve 14 and to avoid interference with the valve stem 14a when the longitudinal moving plate 40 moves in the longitudinal direction. Bar, the long hole 40c is not completely open at one side, as shown in Figure 4, it may be in a closed form and extending in a long width. One side of the longitudinal moving plate 40 is provided with a return spring 40d for restoring movement thereof.

On the other hand, the pressing member 28 is formed with an inclined surface (28a) is formed in a slightly inclined form on one side and the surface facing the pressing surface (40b) of the longitudinal moving plate 40, so that the pressing member (28) The pressing surface 40b facing the inclined surface 28a according to the movement moves the longitudinal moving plate 40 in the longitudinal direction.

The actuator 30 is spaced apart from the cylinder 30c having the piston 30b connected through the pressure member 28 and the connecting rod 30a, and the piston 30b, respectively. A pair of hydraulic pipe lines 30d penetrating the cylinder 30c are provided.

In addition, the switching valve 32 is in communication with the cylinder 30c of the actuator 30 via the hydraulic pipe (30d), and to change the supply path of the operating oil supplied through the hydraulic pipe (30d). It consists of an electronic control valve with a solenoid 32a.

Here, the hydraulic valve 42 is connected to the switching valve 32, the hydraulic pump 42 is used as an operating source of the actuator (30).

On the other hand, the control unit 34 controls the driving of the hydraulic pump 42 and the switching of the switching valve 32 through the operating speed of the engine detected by the vehicle speed sensor 36, respectively, the actuator ( By interlocking the pressing member 28 and the mounting member 26 according to the operation of 30, the mounting length of the valve spring 16 is varied.

In addition, the pressure member 28 is provided with a position sensor 44 for detecting its displacement, the position sensor 44 detects the amount of movement of the pressure member 28 and the control unit ( 34).

Accordingly, the control unit 34 checks the degree of movement of the pressurizing member 28 via the position sensor 44 so that the valve spring according to the movement in the height direction of the mounting member 26 ( By detecting the displacement of the mounting length of the 16, it is possible to feedback control the operation of the actuator 30, it is possible to precisely control the mounting rigidity according to the change in the mounting length of the valve spring (16).

Hereinafter, the operation of the valve spring rigidity variable device according to the present invention will be described in detail.

First, the control unit 34 detects the vehicle speed of the vehicle while driving through the vehicle speed sensor 36, calculates the necessary rigidity of the valve spring 16 according to the vehicle speed, and calculates the calculated stiffness of the valve spring 16. The mounting length of the valve spring 16 for implementing the required rigidity is calculated, and the control for raising the mounting member 26 by the required height is performed according to the calculated mounting length of the valve spring 16. .

At this time, the required rigidity of the valve spring 16 is determined as follows. The force acting on the valve train system is largely due to the inertia force of the inertial mass of the valve system, the pressure of the cylinder acting on the intake / exhaust valve 14 during intake / exhaust, the intake pressure, the inertia force of the valve system, and the cylinder during intake / exhaust It consists of a spring force that can overcome the internal pressure and the intake pressure.

Among them, the spring force is determined by multiplying the safety coefficient according to the dynamic behavior characteristic by the sum of the inertia force due to the inertial mass of the valve system and the force due to the intake pressure acting on the valve.

However, since the inertia force due to the inertial mass of the valve system is proportional to the square of the acceleration of the valve, and the acceleration of the valve is proportional to the square of the rotational speed of the engine, the maximum load of the valve spring 16 required according to the operating speed of the engine is required. Tends to be proportional to the square of the engine's running speed.

That is, the spring force required at low speed operating conditions is much smaller than the spring force required at high speed operating conditions, and the valve spring 16 has excessive rigidity more than necessary when the engine is operated at low speed. Therefore, the driving force of the valve system is required more than necessary at low speed operating conditions.

Therefore, lowering the rigidity of the valve spring 16 is advantageous in terms of the driving force of the valve system, but if the rigidity of the valve spring 16 is too low, a jump and a bounce of the valve occur at high speed, At high speeds, the rigidity of the valve spring 16 should be made large enough to prevent jumps and bounces of the valve.

To this end, at low speeds, the rigidity of the valve spring 16 is reduced to reduce the valve driving force, and at high speeds, the rigidity of the valve spring 16 is increased to prevent jump and bounce of the valve. This improves fuel economy by increasing the mounting length of the valve spring 16 at a low speed, thereby reducing the rigidity of the valve spring 16, and improving the fuel economy by reducing the mounting length of the valve spring 16 at a high speed. The rigidity is increased to prevent jump and bounce of the valve.

That is, in a low speed operating condition in which the operating speed of the engine is low, the control unit 34 performs a control to lower the piston 30b of the actuator 30 through the control of the switching valve 32. The member 28 is lowered, and the longitudinal moving plate 40 in contact with the urging member 28 moves with the restoring force of the return spring 40d to show the height moving plate 38 in FIG. 2. It will descend as shown.

As a result, since the mounting length of the valve spring 16 is increased and its spring stiffness is weakened, the driving torque of the engine for driving the valve train system is reduced to reduce the frictional loss of the engine when the valve is operated. Therefore, the fuel economy is improved.

On the contrary, in the high-speed operation condition in which the engine operation speed is high, the control unit 34 performs the control of raising the actuator 30 through the control of the switching valve 32, and thus the pressurizing member 28 While moving up the inclined surface (28a) of the mounting member 26, the one side inclined surface (40a) of the longitudinal moving plate 40 is pushed to move in the longitudinal direction, according to the movement of the longitudinal moving plate (40) The height moving plate 38 faced via the inclined surfaces 38a and 40a pushes up the bottom surface of the valve spring 16 as shown in FIG. 6.

As a result, since the mounting length of the valve spring 16 is reduced and its spring rigidity is strengthened, the intake / exhaust valve 14 has a stable dynamic behavior without anomalies such as jumping and bounce during operation.

On the other hand, in the condition that the driving speed of the engine is about medium, the control unit 34 adjusts the movement of the mounting member 26 through proper control of the actuator 30 to adjust the mounting length of the valve spring 16. As shown in Figure 5 it is adjusted to a medium length. At this time, the spring stiffness of the valve spring 16 is adjusted to a medium degree to improve fuel economy, and to eliminate abnormal phenomena such as jumps and bounces during operation of the intake / exhaust valve 14.

As described above, according to the valve spring stiffness variable device of the engine according to the present invention, by varying the mounting length of the valve spring 16 of the valve train system in accordance with the operating speed of the engine and changing its rigidity, It is possible to reduce the unnecessary driving torque of the engine for the operation of the valve system to improve the fuel economy, and to eliminate the abnormal behavior of the jump and bounce of the valve under high speed operating conditions.

Claims (7)

An intake / exhaust valve 14 installed on the intake / exhaust valve 14 of the cylinder head 10 to regulate its opening and closing, and a valve spring 16 that provides a restoring force during operation of the intake / exhaust valve 14. ), A retainer assembly 18 for holding the upper end of the valve spring 16 fixed thereto, a tappet 20 seated on the upper end of the intake / exhaust valve 14, and a camshaft 22 at the upper part of the tappet 20. In a valve train system of an engine including a cam (24) mounted on the fan) to open and close the intake / exhaust valve (14), The valve spring 16 has a mounting member 26 for varying its mounting length according to the operating speed of the engine, an actuator 30 for operating the mounting member 26 and an operation of the actuator 30. Valve spring stiffness variable device of the engine, characterized in that for changing the mounting rigidity thereof via a variable means including a control unit for controlling the 34. The method of claim 1, The mounting member 26 is composed of a height moving plate 38 for supporting the bottom portion of the valve spring 16, and a longitudinal moving plate 40 that is in contact with the lower portion of the height direction moving plate 38, Valve spring rigidity variable apparatus of the engine, characterized in that the inclined surfaces (38a, 40a) inclined at a predetermined angle formed on the bottom surface of the height-moving plate 38 and the upper surface of the longitudinal plate (40) . The method of claim 2, The through-hole 38b for receiving the valve stem 14a of the intake / exhaust valve 14 is formed in the height moving plate 38, and the intake / exhaust valve 14 is formed in the longitudinal moving plate 40. A long hole 40c is formed to accommodate the valve stem 14a of the valve and to avoid interference with the valve stem 14a while the longitudinal moving plate 40 moves in the longitudinal direction. Valve spring rigidity variable device of the engine, characterized in that the return spring (40d) is installed for. The method of claim 1, The actuator 30 is connected to a pressing member 28 for the movement of the longitudinal moving plate 40, and an inclined surface 28a is formed at one side of the pressing member 28, and the inclined surface 28a. ) Is the valve spring rigidity variable apparatus of the engine, characterized in that the contact with the pressing surface (40b) formed on one side of the longitudinal moving plate (40). The method of claim 4, wherein The actuator 30 is a connection rod 30a for connection with the pressing member 28, a piston 30b connected to the connection rod 30a, and a cylinder 30c incorporating the piston 30b. It is made, but the cylinder (30c) valve spring stiffness variable apparatus of the engine, characterized in that it has a pair of hydraulic lines (30d) spaced around the piston (30b), respectively. The method of claim 5, The hydraulic valve 30d of the actuator 30 is an engine characterized in that a switching valve 32 having a solenoid 32a controlled by the control unit 34 is connected to change the moving direction of the piston 30b. Valve spring rigidity variable device. The method of claim 4, wherein The pressing member 28 is provided with a position detecting sensor 44 for detecting a displacement thereof, the control unit 34 through the position sensing sensor 44 through the amount of movement of the pressing member 28 through the valve The valve spring stiffness variable device of an engine, characterized in that it detects a change in the mounting length of the spring (16), and feedback control the operation of the actuator (30).