JPH02264104A - Valve system for internal combustion engine - Google Patents

Abstract

PURPOSE:To restrict the consumption of operating oil to a minimum by using high-pressure operating oil only when an intake or exhaust valve is opened, and by operating the intake or exhaust valve with the valve spring energy stored up in it with the lift of the valve when the valve is closed. CONSTITUTION:In a valve system provided with a control valve 1 by which the operating oil of an accumulator 11 is controlled for driving an exhaust valve 6 and an actuator 7, a piston 22 is made up of a main piston 22a of a small diameter part and an auxiliary piston 22b of a large diameter part. In a cylinder 21 for oiltightly guiding the piston 22, a main communication hole 21a for supporting the operating oil to the upper surface of the main piston 22a, an auxiliary communication hole 21b for supplying the operating oil to the upper surface of the auxiliary piston 22b, and a return hole 20b for discharging the operation oil after it has acted on the auxiliary piston 22b are bored. And the exhaust valve 6 is provided with an air spring 40 for energizing it in the closing direction. Thus, since the operating oil is controlled on the basis of the lift of the piston 22 in response to the resistance of the exhaust valve 6 so that it can be acted in two stages, the consumption of operating oil can be restricted to a minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an accumulator type valve operating device for controlling the opening and closing of an exhaust valve or an intake valve of a diesel engine.

[Conventional technology]

As a conventional pressure accumulation type valve operating system, for example, the
There is one described in 2563. This device is pressurized by a hydraulic power source 010 as shown in FIG.
A five-hole control valve 01 that controls the hydraulic oil stored at a constant pressure inside, a cam 02, a roller 03, and a camshaft 04 that drive the valve, and intake and exhaust valves 06 provided on the cylinder cover 05. Actuator 07 powered by hydraulic oil and piping 08
,09. FIG. 8 shows the state in which the intake and exhaust valves 06 are closed, the tappet 03 is located at the second position, and the control valve 01 guides the hydraulic fluid in the pressure accumulator 011 to the lower chamber 07a of the actuator 07 through the pipe 09. Due to the force of the hydraulic oil, the suction and exhaust valves 06 move in three directions and are closed.At this time, the hydraulic oil in the upper chamber 07b of the actuator 07 passes through the piping 08 and the control valve 01 to the hydraulic pressure. When the cam 02 rotates and the roller 03 lifts, the hydraulic oil in the lower chamber 07a passes through the pipe 09 and the control valve 01 and is discharged to the tank 010a. 011 high pressure hydraulic oil is control valve 01
, acts on the upper chamber 07b through the pipe 08, and the force is absorbed,
The suction and exhaust valve 06 resist the cylinder pressure acting on the exhaust valve 06.
Move the valve downward to open the intake and exhaust valves 06. Cam 0
As the roller 2 rotates further, the lift of the roller 03 decreases and when it reaches the base circle, the control valve 01 becomes the state shown in the figure, and the intake and exhaust valves 06 move upward and close as described above.

[Problem to be solved by the invention]

As mentioned above, in the conventional example, the control valve 01 requires five holes, resulting in a complicated and large structure, and the high pressure pipes 08, 09
Since the actuator 07 is also two trees, the actuator 07 is also complicated and inevitably large in size. In addition, high-pressure hydraulic oil is used to open and close the intake and exhaust valve 06, and this high-pressure hydraulic oil is drained into the tank 010a and discarded after operating the actuator O7, so the amount of hydraulic oil consumed is reduced. As a result, energy loss increases and there are problems in that it is difficult to control the valve closing speed of the intake and exhaust valves.

The purpose of the present invention is to solve the problems of the conventional example, simplify the structure of the control valve and actuator, control the valve closing speed, and reduce the consumption of hydraulic oil to the necessary minimum by closing the valve using spring force. An object of the present invention is to provide a valve train for an internal combustion engine that can significantly reduce power loss.

[Means to solve the problem]

A valve train for an internal combustion engine according to the present invention includes a hydraulic pressure source and a pressure accumulator that pressurize and store hydraulic oil, and a control valve and an actuator that control the hydraulic oil in the pressure accumulator to drive an intake valve or an exhaust valve. In a valve train equipped with: The piston is composed of a main piston with a small diameter portion and a sub piston with a large diameter portion; Hydraulic oil is supplied to the upper surface of the main piston to a cylinder that oil-tightly guides the screws 1 to 1. A main communication hole for supplying hydraulic oil to the upper surface of the sub-piston, a sub-communication hole for supplying hydraulic oil to the upper surface of the sub-piston, and an oil drain hole for discharging the hydraulic oil acting on the sub-piston are drilled.

The auxiliary communication hole is arranged to be opened and closed by the sliding movement of the main piston, and the oil drain hole is opened and closed by the sliding movement of the auxiliary piston.

Furthermore, the intake and exhaust valves are provided with valve springs that bias these valves in the valve closing direction.

[For production]

High pressure hydraulic oil is used only to open these intake and exhaust valves.
The valve is closed by an actuator that is operated by a valve spring that is stored as the intake and exhaust valves lift.

As a result, the structure of the control valve, high-pressure piping, and actuator has been simplified and downsized, and the amount of high-pressure hydraulic oil consumed during valve opening operation has been reduced, making it possible to save drive energy.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 shows the main structure of this valve train. 1 is a control valve, and a cam 2 fixed to a camshaft 4 controls a tappet roller 3.
The piston 1a is driven vertically through a cylinder I, which has a hydraulic oil inlet hole IC1, an outlet hole 1d, and an oil drain hole 1e.
It moves freely inside b while maintaining oil tightness. A high-pressure pipe 8 connects the control valve 1 and the actuator 7. The actuator 7 includes a main body 20, a cylinder 21, a piston 22,
It is composed of a lid 23, a check valve unit 30, and an upper chamber 7.
b. It has an intermediate chamber 7C1 and a lower chamber 7a, and the cylinder 21 has a main communication hole 21a that connects the inlet hole 20a and the upper chamber 7b;
A sub-communication hole 21b connecting the artificial hole 20a and the intermediate chamber 7C,
It has an intermediate hole 21C that connects the return hole 20b and the intermediate chamber 7C, a lower hole 21d that connects the return hole 20b and the lower chamber 7a, and an oil path 21e to the check valve Unisol 1 to 30. piston 2
2 has a small-diameter main piston 22a that partitions an upper chamber 7b and an intermediate chamber 7c, and a relatively large-diameter sub-piston 22b that partitions an intermediate chamber 7c and a lower chamber 7a.
a. The auxiliary screw 1-22b slides in the cylinder 21 in an oil-tight manner. The check valve unit 30 includes a stopper 30c and a spring 30.
The valve 30b biased upward by the valve a is oil-tightly guided within the guide 30f, and has a seam) 30d to supply hydraulic oil from the oil passage 21e to the upper chamber 7b and prevent it from flowing in the check direction. , a throttle 30 that discharges air mixed in the hydraulic oil together with the oil.
It consists of e.

The exhaust valve 6 slides within a guide 15 fixed to the cylinder cover 5 and is urged upwardly by a pneumatic valve spring 40, with its upper end abutting against the piston 22.

The pneumatic valve spring 40 is composed of a cylinder 42 that airtightly guides the piston 41, a top 43 that fixes the intake and exhaust valves 6 and the piston 41, and a presser foot 44, and pressurized air is supplied from the air tank 45 through the air hole 42a. is supplied, and the actuator 7 is fixed to the upper part thereof.

The hydraulic pressure tX10 is composed of a tank, a strainer, a high-pressure pump, etc., and sends high-pressure hydraulic oil to a pressure accumulator 11, which stores the high-pressure hydraulic oil.

Next, the opening operation of the intake and exhaust valves 6 will be explained first.

In FIG. 2, the camshaft 4 rotates and the roller tapeno l-3
When the piston 1a rises, the outlet hole 1d is cut off from the oil drain hole 1e and communicates with the inlet hole 1c.) When the piston 1a rises further, the pressure accumulator 11
High-pressure hydraulic oil is supplied to the actuator 7 via the control valve 1, and the inlet hole 20a, the main communication hole 21a, the oil passage 21e,
One hole 20a passes through the check valve unit 30 and enters the upper chamber.
, acts on the intermediate chamber 7c through the auxiliary communication hole 21b, and moves the piston 22 downward as indicated by the mark, resulting in the state shown in FIG. 3. FIG. 3 shows the main communication hole 2 as the piston 22 moves downward.
1a and the upper chamber 7b are just communicating with each other, and the seat 30d remains open until this time, and thereafter closes, resulting in the state shown in FIG. 4. In Figure 4, high pressure hydraulic fluid is inlet hole 2.
0a, the hydraulic fluid acts on the upper chamber 7b through the main communication hole 21a, and the communication between the sub-communication hole 21b and the intermediate chamber 7c is about to be cut off, and when the piston 22 moves further downward with the → mark, the hydraulic oil is in the main chamber 7b. It acts only on the upper surface of the piston 22a and does not act on the upper surface of the sub-piston 22b, resulting in the state shown in FIG. In FIG. 5, the intermediate chamber 7c is the intermediate hole 2]c,
We are in a period where we can communicate with each other. Between the movement amount δ of the piston 22 from FIG. 4 to FIG. 5 (shown in FIG. 4), the oil in the intermediate chamber 7c is expanded, but after FIG. It is set to be ejected.

The drained oil from the intermediate hole 21G returns to the hydraulic source 1 through the hole 20b.
0 tank. Hydraulic oil is applied to the upper chamber 7b on the upper surface of the main piston 22a through the inlet hole 20a and the main communication hole 21a, and the piston 22 moves downward by the mark, reaching the state shown in FIG.

In FIG. 6, the lower chamber 7a and the lower hole 21d are at the point where the communication is cut off, and if the piston 22 descends any further, the oil in the lower chamber 7a will be sealed and the oil pressure will rise, and this force will prevent the piston 22 from descending. Stop slowly. That is, the lower chamber 7a forms a cushion chamber, and the intake and exhaust valves 6 reach the maximum lift position (1.max in FIG. 7) and the valve opening movement ends. The hydraulic oil further enters the upper chamber 7b through the inlet hole 20a, the main
Although it continues to act on the upper surface of the main piston 222 through the sub-communication holes 21a and 21b, the intake and exhaust valves do not move.

The pressure within the cylinder 42 of the pneumatic valve spring 40 is increasing.

Next, the closing action of the intake and exhaust valves 6 will be explained.

The piston 22 moves in the direction indicated by -> in FIGS. 2-6. In the state shown in FIG. 6, when the cam 2 rotates and the tappet roller 3 reaches the base circle, and the control valve 1 enters the state shown in FIG. 20
a, passes through the control valve 1 through the high-pressure pipe 8 and is discharged to the tank of the hydraulic source (10). This biasing force also acts on the piston 22, and the valve closing movement is performed by the air pressure stored in the pneumatic valve spring 40. When the state shown in FIG. 5 is reached from FIG. 6, the intermediate chamber 7c is The intermediate chamber 7c is sealed by the secondary piston 22b through a gap, and the oil pressure in this intermediate chamber 7c rises, and during the displacement δ1 shown in FIG.
2. Gradually slow down the upward movement speed. When the piston 22 further moves in the -> mark direction and reaches the state shown in FIG. 3, communication between the upper chamber 7b and the main communication hole 21a is cut off, the seat 30d of the check valve unit 30 is closed, and the upper chamber 7b is closed. The oil pressure increases and the upper chamber 7b forms a hydraulic cushion chamber. In FIG. 2, the upward movement speed of the piston 22 is further reduced due to the secondary cushioning action of the upper chamber 7b, and the piston 22 continues to move the exhaust valve 6 by an amount δ2 until the exhaust valve 6 is closed and seated. The speed is controlled to be the optimum speed for the valve to close and seat, and the upward movement is completed to complete the valve-closing movement. The above motion is plotted, and the relationship between the lift l of the piston 22 and the crank angle θ is shown in FIG. 7111(b). β is mainly hydraulic oil,
This shows the period of time that acts on the secondary pistons 22a, 22b, and 11 is 9 as shown in FIG. There is the following relationship between the working oil pressure P, the sub-piston diameter d5, the force F1 that pushes down the exhaust valve, and the working oil consumption flow rate Q, and in this case, the exhaust resistance Fv
There is a relationship of F,>Fv.

F, -1--d,, 2P Q, -----ds21 β1 or more 7! During rift I up to max, the hydraulic oil is acting only on the main piston, and the main piston diameter d0
There is the following relationship between F2, the force F2 that pushes down the exhaust valve, and the consumption amount Q2 of hydraulic oil, and the relationship F2>Fv.

F2 = □-□ dffl"P Q2 = -d m2 (1max -j2,) The hydraulic oil consumption Q in the case of the conventional example without a two-stage piston is Q - - d,"Jlmax C++Q2<Q, and the hydraulic oil consumption can be significantly reduced.

In addition, during the valve closing movement, the primary cushion acts for a period of 61 at β2, decelerating the upward movement of the piston 22, and furthermore, the secondary cushion acts during δ2, so that the exhaust valve 6
The closing speed of the exhaust valve can be optimally controlled, extending the life of the exhaust valve.

Although the case where the control valve 1 is mechanically driven by the cam 2 has been described above, it is also possible to drive it electrically or directly use a solenoid valve.

〔Effect of the invention〕

Since the present invention is constructed as described above, the structure of the control valve is
0, the number of high-pressure pipes is reduced to 1, and the structure of the actuator is simplified, creating hydraulic cushioning and eliminating mechanical collision parts, allowing the exhaust valve to gradually complete its opening cycle and can be optimally controlled.

Furthermore, the hydraulic oil is controlled based on the piston lift according to the resistance of the exhaust valve and acts in two stages, reducing hydraulic oil consumption to the necessary minimum, eliminating hydraulic oil drive energy and significantly reducing power loss. can be done.

[Brief explanation of drawings]

1 to 7 relate to the present invention; FIG. 1 is a configuration diagram of an embodiment, FIGS. 2 to 7 are explanatory diagrams of its operation, and FIG. 8 is a diagram corresponding to FIG. 1 of a conventional example. 1... Control valve, 7... Actuator, 1o...
Hydraulic source, 11... Pressure accumulator, 21... Cylinder, 21
a...Main communication hole, 21b...Sub-communication hole, 21c...
・Middle hole, 21d...lower hole, 22...piston,
22a...Main piston, 22b...Sub-piston, 4
0...Air spring. Figure Figure

Claims (1)

[Claims] A hydraulic source (10) and a pressure accumulator (11) that pressurize and store hydraulic oil.
), and includes a control valve (1) and an actuator (7) that control hydraulic fluid in the pressure accumulator to drive an intake valve or an exhaust valve (6); the piston (22) has a small diameter. The main piston (22a) in the section and the sub piston (22a) in the large diameter section
22b), and the cylinder (21) that guides the piston (22) in an oil-tight manner has a main communication hole (21a) that supplies hydraulic oil to the upper surface of the main piston (22a), and a main communication hole (21a) that supplies hydraulic oil to the upper surface of the main piston (22a), and a cylinder (21) that oil-tightly guides the piston (22). A sub-communication hole (21) that supplies hydraulic oil to the top surface
b), and oil drain holes (21c) and (21d) for discharging the hydraulic oil acting on the sub piston (22b), and the main and sub piston (21a) and (21b) are connected to the main piston (22a).
The oil drain holes (21c) and (21d) are arranged to be opened and closed by the sliding movement of the auxiliary piston, and the intake and exhaust valves are also provided with springs (40) that bias these valves in the valve closing direction.
) A valve train for an internal combustion engine.