JPH04287814A - Valve system of engine - Google Patents

Abstract

PURPOSE:To suppress deterioration of intake/exhaust characteristic by providing, on the bottom part of a first piston provided with an electric driving means, a second piston smaller than the first piston, in its diameter and communicating first and second annular recessed grooves formed on the outer circumference part of the second piston with an operating fluid supplying passage and a discharging passage, when the first and second annular recessed grooves are moved to a prescribed position. CONSTITUTION:An electric driving means 6 is provided so as to force reciprocating motion to a first piston 3 provided in a cylinder 2. A plunger 7 serving as a second piston whose one end is faced to a cylinder 2 outer part has a diameter smaller than that of the piston 3, and an intake valve 8 is provided on the outer end of the plunder 7. First and second annular recessed grooves 15, 16 are formed on the outer circumference thereof, and the grooves 15, 16 are communicated respectively with operating fluid supplying exclusive passage 20 and an operating fluid discharging exclusive passage 30 by up and down motion of the piston 3. The electric driving means 6 is connected to an engine control unit 50, and passing timing and electrification time, namely valve opening timing and opening time of the intake valve 8 are controlled accordance to operating condition.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for an engine, and more particularly to a valve train for an engine in which an intake valve or an exhaust valve is opened and closed by an electric drive means.

0002

[Background Art] Conventionally, the intake or exhaust valve of an engine is
It was common to open and close the valve mechanically using a cam mechanism driven by the engine, but when opening and closing the valve mechanically using a cam mechanism like this, the mechanical resistance of the engine increases. Therefore, in recent years, there has been a tendency to adopt a so-called electric valve mechanism that directly opens and closes the valve using an electric drive means such as a solenoid. Japanese Unexamined Patent Publication No. 1983-
(See Publication No. 183805). However, when the valve is directly driven to open and close by an electric drive means such as a solenoid as in this known example, due to its operating characteristics, the larger the amount of displacement, the greater the response of the electric drive means. This has disadvantages in that performance deteriorates and operational noise increases.For this reason, it is not possible to obtain a large valve lift amount, and as a result, there is a disadvantage in that the intake and exhaust characteristics of the engine deteriorate.

[0003] In order to solve this problem, recently, a non-compressible system has been developed that connects the intake or exhaust valve of the engine with an electric driving means (comprised of a piezoelectric element, etc.) that electrically drives the valve to open and close. An engine valve operating system has been proposed in which a displacement amplifying mechanism using a magnetic fluid is used to amplify the displacement of an electric drive means and transmit the amplified displacement to the valve side (Japanese Patent Application Laid-Open No. 1986-1999).
(See Publication No. 58909).

0004

[Problem to be solved by the invention] The above-mentioned Japanese Patent Application Laid-Open No. 61-58
According to the invention described in Publication No. 909, it is true that
It is believed that it is possible to increase the valve lift of the valve without increasing the operating stroke of the electric drive means. However, in this invention, "a first chamber in which a first piston slides and a second chamber in which a second piston that communicates with the first chamber and has a smaller pressure receiving area than the first piston slides. Since the method of "simply filling and enclosing incompressible fluids" is adopted, considering that the first and second pistons slide, there is no risk of leakage of incompressible fluids (working fluids) to the outside. It is impossible to completely prevent this, and as a result, the working fluid decreases over time, making it difficult to operate the valve as it originally did, and there is a risk that the intake and exhaust characteristics may deteriorate over time. It was inconvenient. In such a case, it may be possible to constantly supply the working fluid into the first and second chambers from the outside, but in this case, the working fluid (
When negative pressure is generated inside the room (indoor), excessive working fluid flows into the room from the outside, causing the pressure of the working fluid to rise abnormally, restricting the movement of the piston and eventually the valve, making it impossible to smoothly intake or exhaust air. There is an inconvenience that there is a risk. Furthermore, according to the description of the embodiment in the above-mentioned publication, the direction in which the valve opens is driven by amplifying the displacement of a piezoelectric element, which is an electrical drive means, using hydraulic pressure, but the direction in which the valve closes is Since the valve is driven by the restoring force of the valve spring, the movement of the valve cannot follow the expansion and contraction changes of the piezoelectric element when the engine rotates at high speed, ensuring smooth operation of the valve as shown in Figure 4. This also has the disadvantage that it becomes difficult to do so. In FIG. 4, the solid line indicates the valve lift of the intake valve, and the dotted line indicates the valve lift of the exhaust valve.

[0005]

OBJECTS OF THE INVENTION An object of the present invention is to improve the disadvantages of the conventional example, and to make it possible to control the movement of the intake valve or exhaust valve at a desired timing depending on the driving situation, especially at high engine speeds. Another object of the present invention is to provide a valve operating device for an engine that can suppress deterioration of intake and exhaust characteristics due to uncertainty in valve operation over time.

[0006]

[Means for Solving the Problems] The valve operating device of the present invention includes a cylindrical cylinder, a first piston slidably installed inside the cylinder, and a valve operating device that is connected to one side via the first piston. and a first chamber and a second chamber formed on the other side, respectively.
a chamber, an electric drive means that is housed in the first chamber and is displaced along the longitudinal direction of the cylinder to reciprocate the first piston; and a state in which one end faces the second chamber and the other end faces the outside of the cylinder. and a second piston having a smaller pressure-receiving area than the first piston, which is reciprocally movable along the longitudinal direction of the cylinder. An intake valve or an exhaust valve is integrally provided at the other end of the second piston. Further, the second chamber is filled with a specific compressible working fluid. Further, a first annular groove and a second annular groove are formed at a predetermined interval along the longitudinal direction on the outer circumference of the second piston, and these annular grooves are formed as the second piston moves. A working fluid replenishment passage and a working fluid discharge passage are provided, which communicate the second chamber with the outside when each reaches a predetermined position. This configuration attempts to achieve the above-mentioned purpose.

[0007]

[Operation] When the electric drive means is not generating displacement while the engine is stopped, no pressure is applied to the working fluid, so the valve is held in a closed state by an appropriate original position holding means. When the engine is started and the electric drive means is energized and the electric drive means is displaced in the direction of opening the valve and drives the first piston in that direction, the first piston applies pressure to the working fluid. This fluid pressure acts on the pressure receiving surface of the second piston, and moves (lifts) the valve integrally with the second piston. In this case, the displacement of the electric drive means is the same as that between the first piston and the second piston.
The signal is amplified according to the ratio of the areas of the pistons and is transmitted to the valve. On the other hand, when the electric drive means is no longer energized and is displaced in the direction of closing the valve and drives the first piston in that direction, the second piston
The fluid pressure of the working fluid in the chamber suddenly becomes negative, and the valve returns to its original position. Further, when the first annular groove and the second annular groove formed on the outer circumference of the second piston reach respective predetermined positions as the second piston moves, the second chamber is activated. Since it is communicated with the outside through a dedicated fluid supply passage or a working fluid discharge passage, providing an appropriate oil supply means outside will prevent a shortage of working fluid in the second chamber over time, or an excess due to some reason. In this case, the working fluid is quickly replenished and discharged, and the amount of the working fluid is always kept almost constant.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows a valve operating device 1 for an intake valve that opens and closes an intake port (not shown). This valve train 1 includes a bottomed cylindrical cylinder 2 provided on a cylinder head 10 of an engine, a first piston 3 slidably installed inside this cylinder 2, and a first piston 3 disposed on a cylinder head 10 of an engine. A first chamber 4 and a second chamber 5 are formed on one side and the other side respectively through the piston 3, and the first piston 3 is housed in the first chamber 4 and is displaced along the longitudinal direction of the cylinder 2. an electric drive means 6 for reciprocating movement; and a second piston, which is provided with one end facing the second chamber 5 and the other end facing the outside of the cylinder 2 and capable of reciprocating along the longitudinal direction of the cylinder 2. The plunger 7 is also provided as a plunger 7. As is clear from FIG. 1, this plunger 7 has a pressure receiving surface (end surface) that is much smaller than the pressure receiving surface of the first piston 3, and an intake valve 8 is integrally provided at the other end. There is.

The intake valve 8 is actually provided at a position where it can open and close an inlet of an intake port (not shown) on the side of a cylinder block (not shown). The plunger 7 and the intake valve 8 are constructed of a spring retainer 11 that fits into a stopper 9 fixed to the upper end of the plunger 7 from below in FIG. 1 and a lid member 12 attached to the open end of the cylinder 2. It is biased in the direction of arrow A in the figure by a compression coil spring 13 interposed therebetween. Here, the plunger 7 can reciprocate in the directions of arrows A and B in the figure along a guide member 14 that is provided so as to pass through the cylinder head 10 and the lid member 12. The state shown in FIG. 1 shows a state where the compression coil spring 13 is fully extended and the valve lift is zero. The second chamber 5 is filled with oil as an incompressible working fluid.

Furthermore, in this embodiment, an upper lift check groove 15 as a first annular groove and a lower lift check groove 15 as a second annular groove are formed on the outer circumference of the plunger 7 at a predetermined interval along the longitudinal direction. Lift check grooves 16 are formed, and when these lift check grooves 15 and 16 reach the zero valve lift position shown in FIG. 1 and the maximum valve lift position shown in FIG. 2 as the plunger 7 moves, the second Room 5
A passage 20 dedicated to supplying working fluid and a passage 30 dedicated to discharging working fluid are provided to communicate the working fluid to the outside. To explain this in more detail, the working fluid discharge exclusive passage 30 includes a first passage part 30A having an L-shaped cross section and extending from the second chamber 5 through a part of the lid member 12 to the inner circumferential surface of the guide member 14; It is configured to include a guide member 14 and a second passage part 30B having an L-shaped cross section and formed in the lid member 12 at a corresponding position opposite to the first passage part 30A with the plunger 7 interposed therebetween. At the lower left end of the second passage 30B in the drawing, there is a first check valve 21 that only allows oil to flow outward from the passage 30B and prevents oil from flowing in the opposite direction. It is provided. Similarly, the working fluid replenishment passage 20 is connected to the guide member 1 from the second chamber 5 through a part of the lid member 12.
4, and a cross section formed in the guide member 14 and lid member 12 at corresponding positions on the opposite side of the first passage part 20A via the plunger 7. It is configured to include an L-shaped second passage section 20B. A second check valve 22 is provided at the lower left end of the second passage section 20B in the figure to allow oil to flow only from the outside toward the passage section 20B and to prevent oil from flowing in the opposite direction. It is being In the cylinder block 10 portion outside these check valves 21 and 22, there is an oil passage 40 connected to an oil supply means (engine oil pressure) not shown.
is provided.

The electrical drive means 6 is constructed by coaxially stacking a large number of piezoelectric elements 6A that mechanically generate displacement (extend) when a voltage is applied. This electric drive means 6 is housed in the first chamber 4 on the upper side of the cylinder 2 described above, and one end (lower end in the figure) is in the first chamber 4.
The other end (the upper end in the figure) is fixed to the inner bottom surface (the upper surface in the figure) of the cylinder 2. The electric drive means 6 also includes an engine control unit (hereinafter referred to as "ECU") 50.
is connected, and this ECU 50 determines the energization timing and energization time (
That is, the opening timing and opening time of the intake valve 8 are controlled. In FIG. 1, reference numerals 41 and 42 indicate oil seals.

In the valve train 1 of this embodiment configured as described above, when the electric drive means 6 is not generating displacement while the engine is stopped, no pressure is applied to the oil in the second chamber 5. Therefore, the intake valve 8 (and plunger 7) is held in its original position by the compression coil spring 13 and is in a closed state. When the engine is started and the electric drive means 6 is energized by the ECU 50, each piezoelectric element 6A constituting the electric drive means 6 extends in the axial direction and the electric drive means 6 is displaced in the direction of arrow B. occurs, and the first piston 3 is driven in the direction of arrow B. At this time, this first piston 3
applies pressure to the oil in the second chamber 5, this pressure moves the plunger 7 in the direction of arrow B, and the intake valve 8 is opened via the plunger 7. In Figure 2,
A maximum valve lift state is shown in which the plunger 7 moves and the intake valve 8 is fully open. In this case,
The displacement of the electric drive means 6 is amplified according to the ratio of the areas of the first piston 3 and the plunger 7 and is transmitted to the intake valve 8. Therefore, for example, even if the amount of displacement of each piezoelectric element 6A constituting the electric drive means 6 is on the order of microns, the amount of movement of the intake valve 8, that is, the amount of valve lift, can be on the order of millimeters.

On the other hand, when the ECU 50 stops the power supply, each piezoelectric element 6A constituting the electric drive means 6 returns to its original shape. Therefore, the first piston 3 moves in the direction of arrow A from the position shown in FIG. 2 and returns to its original position (the state shown in FIG. 1). Therefore, the oil pressure in the second chamber 5 suddenly becomes negative, and the intake valve 8 returns to its original position. In this way, the intake valve 8
By reciprocating in the directions of arrows A and B, the intake valve 8 is opened and closed.

In this case, when oil leaks from the oil seal 41 or 42 during use and the oil pressure in the second chamber 5 drops below the specified value, in the state shown in FIG. 1 where the intake valve 8 is not lifted, The check valve 22 is opened by oil pressure from an oil supply means (not shown), and oil flows through the second passage part 20B, the lower lift check groove 16, and the first passage part 20A, which constitute the working fluid supply passage 20. will be replenished. (Here, the amount of oil replenished is the small amount of oil that leaked from the oil seal.) On the other hand,
If for some reason excessive oil is supplied into the second chamber 5 and the hydraulic pressure in the second chamber becomes somewhat higher than the specified value, when the plunger 7 comes down to the position shown in FIG.
The oil in the second chamber 5 flows through the first passage section 30A, which forms the oil discharge exclusive passage 30, the upper lift check groove 15, and the second
The oil passes through the passage portion 30B, and the check valve 2 is opened by the pressure of the oil.
1 is opened, excess oil is immediately drained and the second
The oil pressure in the chamber 5 becomes the specified value. In this way, in this embodiment, the amount of oil in the second chamber 5 is always kept substantially constant.

FIG. 3 shows displacement e, f of the electric drive means (piezoelectric element) 6 at high engine speed in an engine in which the valve device 1 of this embodiment is applied to an intake valve 8 and an exhaust valve (not shown). The relationship between , the valve lift amount c of the intake valve 8, and the valve lift amount d of the exhaust valve is shown. As is clear from this figure, the opening and closing of the intake valve 8 (or exhaust valve) is controlled by the start and stop (on/off) of energization to the electric drive means 6 by the ECU 50, so the timing of opening and closing of the valve is It can be seen that the desired timing can be set according to the software program, and that the displacement of the electric drive means is sufficiently followed even at high rotation speeds.

As explained above, according to this embodiment,
The timing of opening and closing of the intake valves 2, etc. can be controlled by the ECU 50 at desired timings according to the operating conditions of the engine. Settings can be easily changed by changing the software program, making it possible to adapt to other models and offering excellent versatility. In addition, since the displacement of the piezoelectric element is amplified to drive the valve, and the valve is opened and closed using hydraulic pressure, it is more effective than using a mechanical amplification mechanism such as a lever type as the displacement amplification mechanism. Since the mechanical resistance is small, the operational response of the device is improved accordingly, and smooth operation of the valve can be ensured even when the engine is running at high speed. Furthermore, in this embodiment, the amount of oil in the second chamber 5 is reduced by the actions of the upper lift check groove 15, the lower lift check groove 16, the fluid replenishment passage 20, and the fluid discharge passage 30 provided in the plunger 7. Since it is always kept almost constant, the valve lift remains constant even if oil leaks from the oil seal over time or if excessive oil is temporarily supplied for some reason. It is possible to maintain the same good valve operating condition as initially for a considerable period of time, effectively suppressing the deterioration of intake and exhaust performance due to valve malfunction over time. be able to.

[0018]

As the present invention is configured and functions as described above, the displacement of the electric drive means is amplified in accordance with the ratio of the areas of the first piston and the second piston. Since the signal can be transmitted to the intake valve or exhaust valve, by controlling the start and stop of energization to this electric drive means using an appropriate control device, the opening and closing of the intake valve or exhaust valve can be controlled as desired depending on the engine operating conditions. Moreover, since both the opening and closing of the valve are performed by hydraulic pressure, operational response is improved, and smooth operation of the valve can be ensured even when the engine is running at high speed. , a first annular groove and a second annular groove formed on the outer periphery of the second piston, a working fluid replenishment passageway, and a working fluid discharge passageway operate over time into the second chamber of the cylinder. When there is a shortage of fluid or an excess due to some reason, the working fluid is quickly replenished and drained, and the amount of working fluid can be kept almost constant at all times, thereby keeping the valve lift constant. can be kept,
It is possible to maintain the same good valve operating condition as initially for a considerable period of time, and it is said to be able to effectively suppress the deterioration of intake and exhaust performance due to valve malfunction over time. It is possible to provide a valve train for an engine that is unprecedented and excellent.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the embodiment of FIG. 1;

FIG. 3 is a diagram showing the relationship between the displacement of the electric drive means and the valve lift amount when the engine rotates at high speed in the embodiment.

FIG. 4 is a diagram showing an example of a valve lift at high engine speed in a conventional example.

[Explanation of symbols]

1 Valve operating device 2 Cylinder 3 First piston 4 First chamber 5 Second chamber 6 Electric drive means 7 Plunger 8 as second piston Intake valve 15 Upper lift check groove 16 as first annular groove Lower lift check groove 20 as an annular groove of No. 2 Working fluid supply dedicated passage 30 Working fluid discharge dedicated passage

Claims (1)

[Claims] 1. A cylindrical cylinder, a first piston slidably installed inside the cylinder, and first chambers formed on one side and the other side through the first piston. and a second chamber, an electric driving means housed in the first chamber and displacing along the longitudinal direction of the cylinder to reciprocate the first piston, one end facing the second chamber and the other end facing the second chamber. a second piston facing outside the cylinder and having a smaller pressure receiving area than the first piston and capable of reciprocating along the longitudinal direction of the cylinder, the other end of the second piston an intake valve or an exhaust valve is integrally provided in the second chamber, a specific compressible working fluid is filled in the second chamber, and a first valve is provided at a predetermined interval along the outer circumference of the second piston in the longitudinal direction. an annular groove and a second annular groove are formed; a working fluid replenishment passage that connects the second chamber to the outside when the annular groove reaches a predetermined position as the second piston moves; A valve operating device for an engine, characterized in that a passage exclusively for discharging working fluid is provided.