JPS60113008A - Hydraulically operated tappet valve device of internal- combustion engine - Google Patents

Abstract

PURPOSE:To generate large driving force of a valve in the initial period of its opening by providing a power multiplying piston while relax a shock of the valve in the final period of its closing by discharging oil through a throttle, in an oil hydraulic circuit which actuates the valve to be opened and closed by the hydraulic high pressure controlled by solenoid valves. CONSTITUTION:A piston 25 is driven to open a valve 23 by controlling the pressure of oil, fed from an oil hydraulic pump 54, by a solenoid valve 36 to be supplied to a pressure oil chamber 29. The piston 25, closing a passage 35 in the initial period of opening of the valve 23, opens it with large driving force by applying the pressure of oil to a pressure oil chamber 42 of a power multiplying piston 40 so as to transmit the boost pressure to the pressure oil chamber 29 from a passage 47. If the solenoid valve 36 is closed and a solenoid valve 32 is opened, the valve is moved in its closing direction by discharging oil from a passage 34. The piston 25, if it closes the passage 34, relaxes a shock of the valve when it is closed by discharging the oil in the pressure oil chamber 29 through a throttle 30 so as to decrease a closing speed of the valve.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydraulically operated valve train that operates using high pressure hydraulic oil for an internal combustion engine.

(Prior Art) A hydraulically operated valve train as shown in Fig. 1 is known.
In the figure, the rond of the piston 8 that fits into the cylinder 2 formed in the device main body 1 is in contact with the upper end of the exhaust valve 4. A hydraulic oil supply passage 6 and a discharge passage 7 are opened in the hydraulic chamber 5 in the cylinder 2, and each passage 6.7 is connected to a solenoid valve 8.
．． It has 9. Further, each control valve 8.9 is electrically connected to a control device (not shown).

When opening the valve 4, the solenoid valve 8 is opened with the solenoid valve 9 closed, and hydraulic pressure is supplied into the hydraulic chamber 5 to lower the piston 3. On the other hand, when closing the valve 4, the solenoid valve 8 is closed and the solenoid valve 9 is fully opened to drain all the hydraulic oil in the hydraulic chamber 5.The valve spring (not shown) moves the valve 4 upward while pushing up the piston 8 and closes it. .

In the above-mentioned operation, at the initial stage of opening the exhaust valve 4, upward back pressure is applied to the exhaust valve 4, so a large force is required. However, if the valve 4 is slightly opened, the back pressure is released and the pressure is approximately balanced, and after that, the valve can be opened simply by overcoming the valve spring, and only a small amount of force is required.

However, in the above-mentioned conventional example, the valve 4 is operated by a large blade necessary at the initial stage of opening the valve and thereafter, and a large amount of hydraulic oil is required to move the piston 3 with a large diameter. Therefore, the capacity of the hydraulic pump must be increased. Also, even in the early stages of opening the valve, since the configuration is such that the working hydraulic pressure is simply supplied directly to the hydraulic chamber 5 from the supply passage, it is necessary to increase the driving horsepower of the hydraulic pump.

(Objective of the Invention) To provide a hydraulically operated valve train in which the capacity of a hydraulic pump can be reduced and the drive horsepower can also be reduced.

(H' Constituent of the Invention) This is a hydraulically operated valve train for an internal combustion engine which has the following essential requirements.

←) Provide an operating piston that is linked to the intake and exhaust valves.

(1)) Provide a solenoid valve that controls the operating piston with high-pressure hydraulic oil to obtain appropriate valve closing timing.

((3) A booster piston is provided that is operated by high-pressure hydraulic oil via the above-mentioned solenoid valve.

(1) The booster piston acts on the actuating piston only during a limited stroke at the beginning of opening the valve to operate the actuating piston.

(Example) In FIG. 2, an exhaust valve 2 that closes an exhaust boat 22 (an intake boat may also be used) provided in a cylinder head 21
3 integrally has a valve stem 24 extending upward. The valve 23 is always elastically biased in the direction to close the boat 22 by a valve spring 19 compressed between a spring receiver 18 provided at the upper end of the valve stem 24 and the cylinder head 2.

The upper end of the valve stem 24 is connected to the piston rod 2 of the operating piston 25.
6, and the piston 25 is in contact with the lower end of the device body 27.
It is fitted into a cylinder 28 formed therein so as to be slidable in the vertical direction. A hydraulic chamber 29 is formed in the cylinder 28 above the piston 25, and a discharge passage 31 is opened at the upper end surface of the cylinder 29 via a throttle 30. The passage 31 has a solenoid valve 32 in the middle, and the valve body 83 can open and close freely.
It stands out within 1. The passage 31 branches between the throttle 30 and the electromagnetic valve 32, and the branch passage 34 opens on the side wall surface of the cylinder "28" slightly below the upper end surface of the piston 25.

A supply passage 35 opens on the opposite side of the cylinder 28 side wall surface on the same circumference as the exit position of the branch passage 34.
4 and the passage 35 are constantly in communication via an annular groove 50 formed in the circumferential direction of the cylinder 28. The passage 35 has a solenoid valve 36 in the middle, and the valve body 87 can open and close freely.
It stands out within 5. The passage 35 branches between the solenoid valve 86 and 797228, and the branch passage 38 connects to the hydraulic chamber 42 above the large diameter cylinder 41 into which the booster piston 40 fits.
There is an opening 1. The boosting piston 40 consists of a large diameter part 43 forming a hydraulic chamber 42 and a small diameter part 44 formed integrally therewith.The large diameter part 43 is slidably fitted into the large diameter cylinder 41. At the same time, the small-diameter portion 44 is slidably fitted into a small-diameter cylinder 45 that is formed concentrically with the stepped portion below the large-diameter cylinder 41 . Further, the piston 40 is constantly urged upward by a coil spring 46 compressed between the stepped portion between the cylinders 41, 45 and the large diameter portion 43. The bottom surface of the small diameter cylinder 45 and the side wall n of the cylinder 28
+1 upper end portion is communicated with through a passage 47 VC. Note that 48 is the relief hole of the cylinder 28, and 49 is the cylinder 4.
This is the first escape hole.

The upper side of the supply passage 35 is connected to an oil passage 52 having an accumulator 51 in the middle. The oil passage 52 communicates with a high-pressure bending pump 54 of a hydraulic oil supply system 53. The pump 54 is driven by an engine 55, and hydraulic oil is supplied from an oil pan 56. Oil pan 56 (Hoyou Road 57)
Hydraulic oil from the discharge passage 81 of the device main body 27 is returned via.

The engine 55 includes a crank angle IK (phase) detection sensor 61 and various other sensors (not shown) that detect load conditions, rotational speed, etc., and information from these sensors is transmitted electrically. The information is input to the microcomputer 6B in the control device [62]. The computer 63 performs calculations based on the information, determines the appropriate opening/closing timing of the intake and exhaust valves (for example, the valve 23) according to the state of the engine 55, and controls the solenoid valves 82.8.
The trap is configured to cause a predetermined current to flow through the electromagnetic solenoids 64 and 65 of No. 5.

Next, the operation will be explained. When opening the exhaust valve 28vi,
First, the solenoid 65 is energized and activated according to a command from the control device 62, and the valve body 37 of the solenoid valve 36 opens. Since the passage 85 is closed by the actuating piston 25, hydraulic pressure is supplied to the hydraulic chamber 42, and the boosting piston 40
It acts on the upper surface of the large diameter portion 43 of. This allows piston 4o
When the cylinder 45 is lowered, the hydraulic oil in the cylinder 45 is pushed out by the small diameter portion 44, and hydraulic pressure is supplied to the hydraulic chamber 29 through the passage 47.

Here, each diameter 'iD of the large diameter part 48 and small diameter part 44 of the piston 40 is assumed to be (1, and the supply oil pressure t''P from the system 58 is
o, the hydraulic pressure supplied to the hydraulic chamber 29 is PoX(D
/d). That is, (D/d) > 1 Tearuca et al.
The hydraulic pressure increased by (D/d) times is supplied to the hydraulic chamber 29.

The high pressure supplied to the hydraulic chamber 29 causes the piston 25 to
When the valve spring 19 and the back pressure on the exhaust valve 28 are overcome and the exhaust valve 28 descends slightly, the exhaust valve 28 opens and the exhaust port 22 is opened.
Pressure is released to the side. Therefore, from this point on, the piston 25 only has to resist the valve spring 19. When the piston 25 further slides downward, the hydraulic chamber 29 opens to the supply oil passage 35 and the branch passage 34 . As a result, the hydraulic chamber 29
The internal pressure drops to Pa, and then the piston 25 is moved downward by the working oil pressure PO directly supplied from the passage 35 until the valve 28 is at the fully open position.

When closing the valve, the solenoid valve 36 is closed and the solenoid valve 32 is opened according to a command from the control device 62.

As a result, the hydraulic oil passes through the oil passage 57 to the oil pan 56.
However, due to the resistance of the passage, the piston 25
will never return to normal. The piston 25 is returned to its initial state by the force of the valve spring 19, and at this time, a hydraulic pressure P' converted to the spring force of the valve spring 19 is generated in the hydraulic chamber 29. In the boosting piston 4o, the piston 40 is returned to its original state by the oil pressure P° applied to the small diameter portion 44 and the coil spring 46. Here, the supply passage 35 communicates with the discharge passage 31 via the annular groove 50 even after being closed from the hydraulic chamber 29 by the piston 25 . Therefore, due to the effect of the throttle 3o, the pressure inside the small diameter cylinder 45 exceeds the pressure in the hydraulic chamber 42, so the piston 4
o will slide upward and return to its original state. The restrictor 8o has the role of softening the shock until the piston 25 stops after closing the branch passage 34tl, and one and the exhaust valve 23 are seated smoothly on this.

When the valve-opening operation is to be performed again, the solenoid valve 32 is closed and the solenoid valve 36 is punched open, whereby the valve-opening operation is performed again. By controlling the operation of both electromagnetic valves 32 and 36 by the control device 62 in this manner, the valve opening and closing operations can be performed repeatedly.

Note that the actuating piston 25 due to the action of the boosting piston 4o
The sliding stroke is long enough to relieve the back pressure of the exhaust valve.

(Effect of the invention) The boosting piston 40 acts on the operating piston 25 only during a limited stroke when the valve 23 begins to open.
5 is activated; (~ Operating piston 2
5 and its cylinder 28 can be made smaller in diameter.

(g) Since the amount of hydraulic oil supplied is small, the capacity of the hydraulic pump 54 can be reduced.

(Q) Since the working oil pressure can be lowered, the driving horsepower of the hydraulic pump 54 can be reduced.

(Φ　Thus, the entire hydraulically operated valve train can be downsized.

(Another embodiment) ←) The hydraulic pump 54 is driven by the engine 55 tL
For example, an electric motor driven type may be adopted.

(b) As the hydraulically operated valve train main body 27, a structure as shown in FIG. 3 may be adopted. In FIG. 3, the upper end of the valve stem 24 is in contact with the lower end of the piston rod 72 of the working piston 71 with a diameter of /J"l, and the histone 71 is inside the cylindrical cylinder 73 which is fitted into the device main body 27. A hydraulic chamber 74 is formed in the upper part of the cylinder 78, and a cylinder large diameter part 76 is formed at the upper end of the cylinder 73 via a stepped part 75vi. A radial force boosting piston 77 is fitted.That is, the hydraulic chamber 74 is formed surrounded by the cylinder 7B and both pistons 71 and 77.A boat 78 in the radial direction of the cylinder 78 is fitted in the middle part of the cylinder 78. Boat 78 opened.
communicates with a discharge passage 81 via a valve body 80 of the solenoid valve 79. Further, the boat 78 branches in the middle to form a bypass passage 82.

On the other hand, the supply passage 85 has a solenoid valve 86 in the middle, and its valve body 87 protrudes into the passage 85 so as to be openable and closable, and the passage 85 is formed above the boosting piston 77 via a ball-shaped check valve 88. It communicates with a hydraulic chamber 89. Check valve 8
The bypass passage 82 is opened in the passage 85 between the hydraulic chamber 89 and the solenoid valve 86, and the bypass passage 82 is connected to the hydraulic chamber 89 and the bypass passage 82.
A throttle 90 (small diameter passage) is formed between the two. Note that a check valve spring 9 is provided between the check valve 88 and the piston 77.
1 has been reduced. Further, the lower portion of the cylinder large diameter portion 76 communicates with the outside via relief holes 92,98.

Next, the operation will be explained. Hydraulic pressure PQ is always present in the hydraulic oil supply passage 85, and when the valve is opened, the solenoid valve 86 opens and the hydraulic pressure is applied to the boosting piston 77 through the check valve 88. At the same time, hydraulic pressure is supplied to boat 78 through passage 82, but valve 79 is closed and no hydraulic pressure can escape. Therefore, in the early stages of opening the valve, the hydraulic pressure acts only on the boosting piston 77', and by pushing down the actuating piston 71 with a large acting force, the valve is slightly opened.

As the piston 77 continues to descend, the piston 77 itself closes the escape hole 92. Subsequently, the boat 78 opens to the hydraulic chamber 74, the hydraulic pressure from the boat 78 is applied to the upper part of the piston 71, and the booster piston 77 comes into contact with the stepped portion 75. After this, the piston 71 descends with the amount of oil corresponding to the operating screw (y71).

When closing the valve, the solenoid valve 86 is closed and the solenoid valve 79 is opened. As a result, the hydraulic oil is discharged from the passage 81, and no oil pressure is supplied, so that the piston 71 is removed from the valve spring 19 (Fig. 2).
pushed up by the force of

At this time, the piston 71 has an inertial force, but the shock when the seat is not seated is alleviated by the piston 77.

That is, since the piston 77 is lowered by the spring 91, the piston 71 comes into contact with the piston 77 and pushes it upward, whereby the hydraulic fluid in the hydraulic chamber 89 is discharged from the throttle 90. This throttling effect applies the brakes just before the driver is seated, mitigating the shock.

In other words, the piston 77 functions as a boosting mechanism during the initial stage of the valve operation, and functions as a shock mitigation mechanism at the end of the operation.

[Brief explanation of the drawing]

Figure 1 shows conventional hydraulic operation! 1iIII vertical sectional view of the valve train,
FIG. 2 is a layout diagram of a hydraulically operated valve train according to the present invention, and FIG. 3 is a schematic vertical cross-sectional view of another embodiment. 23.Exhaust valve (an example of an intake/exhaust valve), 25.71...
・Operating piston, 32.86.79.86... Solenoid valve, 40.77... Boosting piston

Claims (1)

[Claims] In a hydraulically operated valve train for an internal combustion engine, the solenoid valve is provided with an operating piston linked to intake and exhaust valves, and a solenoid valve that controls the operating piston with high-pressure hydraulic oil to obtain appropriate valve opening/closing timing. A booster piston operated by high-pressure hydraulic oil via the valve is provided, and the booster piston operates the operating piston by acting on the operating piston only during a limited stroke at the beginning of opening the valve. Hydraulically operated valve device for internal combustion engines.