JP2001280109A - Hydraulic valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic valve system in which a pressure oil amount required for driving intake and exhaust valves is reduced as small as possible and an amount of energy required for the driving is reduced to reduce power loss of an engine. SOLUTION: The hydraulic valve system for driving the intake and exhaust valves of an internal combustion engine, comprises: a pressure chamber 4, which is formed at a time of closing a valve 2 of the intake valve or the exhaust valve, and of which pressure receiving face 9 is a rear end face of the valve; a low pressure hydraulic cylinder 3 connected with the pressure chamber at a time of opening the valve and moving the valve by a predetermined amount; an oil pressure supply system supplying the pressure oil to the pressure chamber at the time of opening the valve; a spring 14 to emergize the valve in the opening direction. When the valve opens, the pressure oil is supplied from the oil pressure supply system to the pressure chamber to apply kinetic energy to the valve in the valve opening direction until the pressure chamber is connected to the hydraulic cylinder. After that, movement of the valve in the opening direction is continued by inertia force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an internal combustion engine,
The present invention relates to a hydraulic valve train for driving an exhaust valve.

[0002]

2. Description of the Related Art Conventionally, a valve mechanism for driving intake and exhaust valves of an internal combustion engine has a camshaft driven by a crankshaft, and is pressed by a convex portion of a cam piece which is disposed on the camshaft and rotates. Generally, the valve is opened against a spring biased in the normally closed direction.

On the other hand, since the optimal intake and exhaust timing of the internal combustion engine depends on the operating state, especially the engine speed, a variable valve mechanism for controlling the valve opening timing and the like has been conventionally considered.
Many conventional variable valve mechanisms have a mechanism that mechanically changes the phase of a cam or mechanically switches so that another cam having a different phase or cam lift is effective. With this configuration, it is possible to relatively easily perform variable control of the phase and the lift amount.

[0004] In addition, a valve operating device that drives an intake and exhaust valve by hydraulic pressure instead of a mechanical driving device has been proposed.

For example, Japanese Utility Model Laid-Open Publication No. 61-160204 discloses a valve in which the valve is opened and closed by a complete hydraulic operating force without using a camshaft or a valve spring as shown in FIG. . In this conventional example,
Hydraulic oil is supplied from the hydraulic tank to the high-pressure oil tank by a pump. By supplying and discharging oil from the high-pressure oil tank while controlling the hydraulic cylinder provided at the rear end of the valve with four valves, a free timing and a lift amount can be performed. Has become.

Further, in the variable valve apparatus disclosed in Japanese Patent Application Laid-Open No. 9-4424, a cam drives a cam-side plunger, pressurizes hydraulic oil in a hydraulic chamber, sends it to a valve drive mechanism, and, if necessary, The valve lift is made variable by releasing the pressurized hydraulic fluid to the low pressure side at the appropriate timing.

[0007] However, the conventional technique disclosed in Japanese Utility Model Application Laid-open No. Sho 61-1602.
In 04, since the spring in the valve closing direction is abolished and both the valve opening and valve closing are driven by the urging force of hydraulic pressure, the degree of freedom in controlling the on / off valve is improved. Four valves must be controlled at an appropriate timing with respect to the valves.
In the case of a multi-cylinder internal combustion engine, six valves need to be controlled by the number of cylinders, which is difficult to realize in practice.

Further, in Japanese Patent Application Laid-Open No. Hei 9-4424, the lift amount of the valve mechanism can be controlled, but the driving force is ultimately obtained by the pressing force of the plunger due to the rotation of the cam. It cannot be changed.

[0009]

In a conventionally proposed valve operating mechanism driven by a mechanical cam piece lift curve, or in a variable valve operating mechanism for changing or switching the phase of the cam, the mechanism is ultimately used. Since the valve opening / closing timing and lift amount are completely controlled by the cam piece, even if a variable mechanism is provided, the degree of freedom of the variable control width is low, and if the required specifications of the valve operating mechanism are different, a new camshaft and The peripheral mechanism had to be redesigned. Further, since the method of controlling the valve opening timing and the method of controlling the lift amount are different, there is a problem that changing the valve opening time and the lift amount complicates the structure.

On the other hand, as for a valve operating device using hydraulic pressure, for example, a valve operating device disclosed in the above-mentioned document is known, but as described above, there are still problems to be solved.

[0011] The present invention relates to a valve operating device using hydraulic pressure,
An object of the present invention is to provide a valve operating device capable of reducing the amount of pressure oil for driving an intake / exhaust valve of an internal combustion engine as much as possible, reducing the energy required for driving, and reducing the power loss of the engine. It is another object of the present invention to provide a valve mechanism capable of freely changing a lift timing and a lift amount in such a valve train.

[0012]

According to the present invention, there is provided a hydraulic valve train for driving an intake valve or an exhaust valve of an internal combustion engine. A pressure chamber (4) formed when the valve (2) of the valve or the exhaust valve is closed and having a rear end surface of the valve (2) as a pressure receiving surface (9); and a valve (2) when the valve is opened. A low-pressure hydraulic cylinder (3) to which the pressure chamber (4) is connected when a fixed amount is moved; a pressure oil supply device for supplying pressure oil to the pressure chamber (4) when the valve is opened; ) In the valve closing direction, and when the valve is opened, the pressure oil supplied from the pressure oil supply device to the pressure chamber (4) causes the pressure chamber (4) to press the hydraulic pressure. Until connected to the cylinder (3), the valve (2) has a kinetic energy in the valve opening direction. Give over, then due to the inertia force,
The valve (2) continues to move in the valve opening direction.

Further, the hydraulic cylinder (3) is connected to another hydraulic cylinder (3 ') by a communication passage (33), and an adjusting valve (3) is connected to the communication passage (33).
The lift amount and speed of the valve (2) are changed by adjusting the opening degree of 4).

The pressure supply port (21) for supplying pressure oil to the pressure chamber (4) is provided with a working piston (5) for shutting off the pressure supply port (21). ), A pressure control chamber (7) provided with a control valve (17) is formed on the side opposite to the pressure supply port (21). A pressure accumulator (23) for accumulating pressure is provided, and pressure oil from the pressure accumulator (23) is supplied to the pressure control chamber (7) and the pressure supply port (21) side of the working piston (5). When the valve is opened, the control valve (17) is opened to lower the oil pressure in the pressure control chamber (20), the working piston (5) is moved, and the pressure oil is supplied to the pressure chamber (4). It is characterized by doing.

According to the above arrangement, in the hydraulic valve operating apparatus of the present invention, the hydraulic energy for driving the intake and exhaust valves is applied only at the initial stage when the valve is opened. Regarding the opening and closing valve timing, there is no mechanical restriction like a camshaft,
Free timing can be set.

Further, after the valve 2 is opened, by controlling the opening degree of the regulating valve 34 provided in the communication passage 33, the lift amount and the lift speed of the valve 2 can be freely changed.

According to this configuration, various variable controls can be performed by changing the pressure initially applied to the valve, the supply time of the pressure, the opening of the regulating valve, the pressure of the accumulator, etc. It is possible to realize a type valve train.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of an external appearance of a valve train of the present invention, and FIG. 2 shows a specific configuration thereof.

The hydraulic valve operating apparatus 1 of the present invention drives an intake / exhaust valve 2 slidably held up and down. The valve 2 is urged in a valve closing direction by a spring flange 13 provided around the axis of the valve 2 and a spring 14 provided in a spring chamber 32 in a valve case 31.

The rear end of the valve 2 has a pressure chamber 4 and the rear end of the valve 2 has a pressure receiving surface 9 to which a driving force is applied.
It has become.

The pressure chamber 4 is provided with a pressure supply port 21 for supplying hydraulic oil to the pressure chamber, and a working piston 5 controlled by a pressure control unit 6 for opening and closing the pressure supply port. It is.

A pressure reservoir 8 is provided at the tip of the working piston 5 for urging the working piston upward (in the valve opening direction) by supplying high-pressure working oil. It has a pressure control chamber 7 that is supplied with oil and urges the working piston 5 downward (to close the valve) together with a built-in spring.

The pressure reservoir 8 and the pressure control chamber 7 are connected to a high-pressure oil supply path (19, 20, 28, 2) from a pressure accumulator 23 for accumulating high-pressure hydraulic oil supplied from a hydraulic pressure supply pump.
Hydraulic oil is constantly supplied through 9).

When the working piston 5 is closed, high-pressure hydraulic oil is supplied to its rear end (pressure control chamber 7) and front end (pressure reservoir 8), and the biasing forces in the valve opening direction and the valve closing direction are substantially balanced. The valve is kept closed by a spring disposed in the pressure control chamber 7.

When the valve 2 is lowered when the valve is opened, the operation piston 5 is raised by the operation of the pressure control unit 6 which opens and closes the passage 16 of the orifice which faces the pressure control chamber 7 and is opened to the reservoir tank on the other hand. The hydraulic oil is supplied to the pressure chamber 4 while being injected. The operation will be described below with reference to FIG.

The pressure control unit 6 includes an electromagnetic coil 35,
The armature 17 includes a spring 36 and a leak passage 18. In a steady state (when the valve 2 is closed), the armature 17 closes the orifice 16, and the working piston 5 prevents the high-pressure working oil from being injected from the pressure supply port. The pressure supply port is closed (FIG. 3- (a)).

When the valve 2 is opened, the pressure control unit 6 first energizes the electromagnetic coil 35 to raise the armature 17, and the orifice 16 is opened. When released, the high-pressure hydraulic oil in the pressure control chamber 7 leaks through the orifice 16, so that the pressure in the pressure control chamber 7 decreases.

When the pressure in the pressure control chamber 7 decreases, the pressure balance with the pressure reservoir located at the tip of the working piston 5 is broken, and the pressure reservoir rises due to the high-pressure hydraulic oil (valve opening direction).
Of the pressure control chamber 7 and the biasing force of the spring in the valve closing direction, and the working piston 5 rises.

When the working piston 5 rises, the pressure supply port 2
1 is opened, and the high-pressure hydraulic oil supplied from the accumulator 23 is supplied while being injected toward the pressure chamber. Pressure accumulator 2
The pressure of No. 3 can be set arbitrarily. The injected oil collides with the pressure receiving surface at the rear end of the valve, giving kinetic energy in the downward direction to the valve 2 and moving the valve 2 in the valve opening direction (FIG. 3).
(B)).

When the valve 2 moves in the valve opening direction by a predetermined amount, the pressure chamber 4 communicates with the cylinder 3 located therebelow, and when the high-pressure hydraulic oil injected into the pressure chamber 4 flows into the low-pressure cylinder, the pressure is immediately increased. Decrease. Even if the pressure decreases, the valve continues to move in the valve opening direction by a predetermined amount with the initially applied kinetic energy of the valve (FIG. 3 (c)).

Next, the specific operation of the entire hydraulic valve train will be described with reference to the timing charts shown in FIGS.

In the embodiment shown in FIG. 2 according to the invention, the valve 2 has a cylinder 3 which is in communication with the pressure chamber 4 after starting the lift and another cylinder 3 'which is in communication with the cylinder 3. . The cylinders 3 and 3 'are connected through a communication passage 33. An adjusting valve 34 whose opening area can be variably controlled is provided in the middle of the communication passage. A relief valve 27 for opening the valve at low pressure and releasing the hydraulic oil is provided in the cylinder 3 ′ located downstream of the cylinder 3. Further, a replenishing passage 38 for replenishing hydraulic oil in accordance with a pressure drop of the cylinder 3 'is also provided.

The valve opening operation of the valve 2 in this embodiment will be described. The target valve opening timing t1 of the valve is determined according to the operating state of the engine (details are omitted). Energization of the pressure control unit 6 is started at this timing. The operation in which the operating oil pressure is supplied from the pressure supply port 2 to the pressure chamber 4 by the pressure control unit 6 is as described with reference to FIG. The power supply start timing is set retroactively for a predetermined period since there is a time lag from the start of power supply to the actual operation hydraulic pressure being supplied and the valve being lifted.

At time t1, the lift of the valve 2 is started. In the initial stage of the lift start, the pressure chamber 4 is a substantially closed space by the pressure receiving surface of the valve 2 as shown in FIG. Given energy, the lift increases rapidly. The lift amount is a predetermined amount ((a) in FIG. 4)
When the pressure exceeds the pressure line 4, the pressure chamber 4 communicates with the cylinder 3 and the pressure applied to the pressure receiving surface 9 decreases rapidly. At this point, the injection of the hydraulic oil from the pressure control unit 6 is basically stopped, and the valve lift is continued by the applied kinetic energy.

After the pressure chamber 4 communicates with the cylinder 3, the volume of the cylinder 3 increases with the movement of the valve. Therefore, hydraulic oil flows into the cylinder 3 from the supply path 38 via the cylinder 3 ′ and the communication path 33.

Here, energization for opening the previously closed regulating valve 34 is started (t1). Actually, even when the control valve is energized at t1, the control valve opens with a time delay. Therefore, the control valve is actually opened until the valve lift exceeds the (a) line. Is preferred. If the opening degree of the adjustment valve 34 is large, the replenishment from the cylinder 3 'is performed quickly, and a high lift speed is maintained without impairing the valve opening speed of the valve lift.

The graph shown by the one-dot chain line in FIG. 4 is a case where the regulating valve is fully opened, that is, the opening degree is 100%. In this case, the hydraulic pressure is quickly supplied to the cylinder 3 and the deceleration of the valve lift is minimized. Pressed (maximum lift speed). The solid line shows the case where the opening of the regulating valve 34 is 50%, and the valve lift is as shown by the solid line. The case where the opening degree is 20% is shown by the two-dot chain line. Since the supplement of the operating oil pressure to the cylinder 3 'to the cylinder 3 is greatly limited by the opening degree of the adjustment valve 34, the valve lift speed is suppressed to a low value. . The valve controlled in this way lifts until the maximum lift is reached.

When the maximum lift required by the valve has been reached, the regulating valve 34 is completely closed. Since the valve is lifted while increasing the volume of the cylinder 3, the volume cannot be expanded if the supply of hydraulic oil from the cylinder 3 'through the communication passage 33 is interrupted. That is, when the adjustment valve 34 is closed in the maximum lift state, the valve stops its movement and the lift state is maintained. Further, in order for the valve to return to the valve closing side, it is necessary to return the hydraulic oil supplemented to the cylinder 3 to the cylinder 3 'side through the communication passage 33 this time. Next, valve closing control of the valve 2 will be described.

The valve closing control is performed based on a target valve closing timing (t3: details are omitted) determined according to the operating state of the engine. The valve is in maximum lift,
That is, from the state where the adjustment valve 34 is fully closed, the adjustment valve 34 is opened based on the target valve closing timing. By opening the regulating valve 34, it is possible to return the hydraulic oil from the cylinder 3 to the cylinder 3 ′, which has been disconnected, and the valve 2 is moved while the volume of the cylinder 3 is reduced by the spring force of the spring 14. The valve closes.

As in the case of opening the valve, the valve closing speed can be variably controlled by adjusting the opening degree of the regulating valve 34 during the valve closing operation. The opening 1 indicated by a solid line at t3 in FIG.
In the case of 00%, the valve closing speed becomes the maximum, and when the opening is reduced (50%) as shown by the dotted line, the valve closing operation of the valve becomes slow. Also, when the pressure chamber 4 starts to be closed by the pressure receiving surface 9 at the rear end of the valve at the time of the valve closing operation, the valve only leaks out from a slight gap around the rear end of the valve. You. This damping effect is an undesired bounce of the valve (closed valve opens again due to the reaction of closing momentum)
Also has the effect of preventing.

At the time of the maximum lift, the regulating valve 34
By closing the valve, the valve lift is stopped and the lift state is maintained, which is indicated by the dotted line (b) in FIG.
When the regulating valve 34 is closed at the lift amount as described in the above, that is, at the time point t2 'after a predetermined time has elapsed from t1, the lift amount can be controlled to be small (in this case, a half lift). When closing the valve (for example, t4 ')
The adjustment valve 34 may be opened in the same manner as described above.

When the engine has a plurality of cylinders, the accumulator of the above embodiment may be a common rail which is a common accumulator for each cylinder. In order to maintain the pressure constant, a pressure sensor provided in the accumulator is used. Is preferred, but a pressure holding structure using a relief valve that relieves at a constant pressure may be used.

The pressure hydraulic oil may be a dedicated hydraulic oil, or it is needless to say that the same control can be performed by using an engine lubricating oil or a fuel oil. Further, the supply of the working oil to the accumulator is performed by a pump. However, when a common rail is used in a fuel supply system for the combustion chamber of the engine, the pressure can be supplied from the common rail.

[0044]

As described above, according to the present invention, the kinetic energy of the valve provided by the hydraulic oil for driving the intake and exhaust valves can be effectively utilized, and the amount of hydraulic oil for driving can be minimized. Therefore, the power required to increase the pressure of the hydraulic oil is reduced, and the power loss of the internal combustion engine is reduced.

[Brief description of the drawings]

FIG. 1 is a drawing showing the external appearance of a valve train according to the present invention.

FIG. 2 is an internal sectional view showing the embodiment of the present invention.

FIG. 3 is a view showing the operation of the ac pressure control unit and the opening / closing control of the valve.

FIG. 4 is a timing chart of an adjustment valve 34, a solenoid valve H, and a valve lift according to the present invention.

FIG. 5 is a view showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic valve gear 2 Intake and exhaust valve 3 Cylinder 4 Pressure chamber 5 Working piston 6 Pressure control unit 7 Pressure control chamber 8 Pressure reservoir 9 Pressure receiving surface 10, 11, 18 Leak passage 12 Reservoir tank 13 Spring flange 14 Valve spring 15 Intake / exhaust port 16 Orifice 17 Control valve armature 19, 20, 28, 29 High pressure oil supply path 21 Pressure supply port 22 ECU 23 Accumulator common rail 24 Pressure sensor 25 Hydraulic supply pump 26 Check valve 27 Relief valve 30 Cylinder head 31 Valve case 32 spring chamber 33 communication passage 34 adjustment valve 35 electromagnetic coil 36 spring 37 pump control valve 38 supply path

Claims (3)

[Claims] 1. A hydraulic valve train for driving an intake valve or an exhaust valve of an internal combustion engine, wherein the valve is formed when a valve (2) of the intake valve or the exhaust valve is closed, and a rear end face of the valve (2) is provided. A pressure chamber (4) having a pressure receiving surface (9), and a low-pressure hydraulic cylinder (3) to which the pressure chamber (4) is connected when the valve (2) moves by a predetermined amount when the valve is opened. A pressure oil supply device for supplying pressure oil to the pressure chamber (4) when the valve is opened, and a spring (14) for urging the valve (2) in a valve closing direction. Kinetic energy in the valve opening direction is applied to the valve (2) until the pressure chamber (4) is connected to the hydraulic cylinder (3) by the pressure oil supplied from the supply device to the pressure chamber (4). And then the valve (2) continues to move in the valve opening direction due to inertial force. Hydraulic valve operating apparatus characterized. 2. The hydraulic cylinder (3) is connected to a communication passage (3).
3) is connected to another hydraulic cylinder (3 '), and the opening of a regulating valve (34) is adjusted in the communication passage (33) so that the lift amount and speed of the valve (2) can be adjusted. 2. The hydraulic valve gear according to claim 1, wherein the hydraulic valve gear is changed. 3. An operation piston (5) for shutting off the pressure supply port (21) is provided at a pressure supply port (21) for supplying pressure oil to the pressure chamber (4), and the operation piston (5) is provided. ), A pressure control chamber (7) provided with a control valve (17) is formed on the side opposite to the pressure supply port (21). A pressure accumulator (23) for accumulating pressure is provided, and a pressure supply port (2) of the pressure control chamber (7) and the working piston (5) is provided.
On the 1) side, pressure oil from the pressure accumulator (23) is supplied. When the valve is opened, the control valve (17) is opened to reduce the oil pressure in the pressure control chamber (20), and The hydraulic valve train according to claim 1 or 2, wherein the piston (5) is moved to supply pressure oil to the pressure chamber (4).