JPH0791969B2 - Valve drive for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve drive device which opens and closes an intake valve or an exhaust valve of an internal combustion engine such as a diesel engine by hydraulic pressure.

(Prior Art) Conventionally, in a diesel engine for a ship, since its rotational speed is low, hydraulic pressure is used for an intake valve that supplies intake air (air) to a combustion chamber of a cylinder and an exhaust valve that discharges combustion gas in the cylinder. It is known to drive the valve drive device to open and close it. That is, in the valve drive device, the intake / exhaust valve is biased in the valve closing direction by a coil spring, an air spring (air cylinder), etc., and the piston of the hydraulic cylinder is brought into contact with the upper end of the valve stem of the intake / exhaust valve. By supplying high-pressure hydraulic oil to the pressure chamber of the hydraulic cylinder, the piston is moved to open the intake / exhaust valve against the biasing force of the coil spring or the like.

(Problems to be Solved by the Invention) However, this conventional valve drive device has the following problems. That is, in this valve drive device, an electromagnetic switching valve is provided in the hydraulic oil supply pipe connecting the pressure chamber of the hydraulic cylinder and the hydraulic oil source such as the hydraulic oil pump, and the hydraulic oil return pipe connecting the pressure chamber and the hydraulic oil tank. Is arranged, and the electromagnetic switching valve is switched to control the opening / closing timing of the valve and the supply / discharge control of the hydraulic oil. Therefore, as the flow rate of hydraulic oil increases due to the upsizing of the engine, the solenoid switching valve becomes larger and the piping system also becomes larger.
This may result in increased costs and reduced workability in maintenance and inspection work.

Also, in the hydraulic cylinder, the chamber on the side opposite to the pressure chamber with respect to the piston is open to the atmosphere, so in the state where hydraulic oil is supplied to the pressure chamber during the valve opening stroke, the pressure difference between the chambers on both sides of the piston is Large, the hydraulic oil leaks from the gap between the cylinder wall and the piston, causing the pressure in the pressure chamber to drop, and the valve holding force becomes insufficient, making the valve lift unstable and causing energy loss due to hydraulic oil leakage. Also increases.

Further, regarding the exhaust valve, as shown in the lower half of FIG. 5, the opening of the valve starts slightly before the bottom dead center (BDC) at the end of the expansion stroke. On the other hand, the gas pressure in the engine cylinder is, as shown in the upper half of the figure, the top dead center of the piston (TD
C) Immediately after it became maximum due to explosion, it decreased due to gas expansion accompanying the lowering of the piston, but it still shows a high value when the exhaust valve starts to open. The in-cylinder gas pressure P _ZEO at this time has a value of 10 to 15 kgf / cm ² G at the rated output of the 4-cycle engine for a ship, and the exhaust valve must overcome this high gas pressure and start the valve opening operation. Specifically, as shown in FIG. 6, the pressure receiving area on the combustion chamber side of the exhaust valve V _E is A ₃ , the pressure receiving area on the exhaust pipe side is A ₄ , and the pressure inside the exhaust pipe is P _E.
Is the force that the valve body V _E ′ of the exhaust valve V _E receives from the combustion gas.
F _G is F _G = A ₃ · P _ZEO −A ₄ · P _E …, and if both pressure receiving areas A ₃ and A ₄ are approximately equal, F _G = A ₃ · (P _ZEO −P _E )… Becomes When the dimensions of each part such as the hydraulic cylinder and the piston inside it are set in advance, the driving force F _{OPEN that} is required for opening the valve is as follows: the pressure receiving area of the hydraulic piston is A ₁ , the hydraulic fluid pressure is P _S , The closing force of the exhaust valve due to the air spring is F _A
F _OPEN = P _S · A ₁ −F _A −F _G …, and it is required to set the hydraulic oil pressure P _S so that the exhaust valve V _E can be sufficiently accelerated by this driving force F _OPEN . It Then, the cylinder pressure P _ZEO and the exhaust pipe pressure
Since the difference between P _E and P _ZEO −P _E varies depending on the load condition of the engine and the magnitude of the explosion condition in the cylinder, the above exhaust valve V _E
The force received by F _G also fluctuates.

However, since the operating oil pressure P _S is constant and the set value cannot be easily changed during the operation of the engine, a high oil pressure corresponding to the rated output state of the engine is fixed and set. Therefore, under operating conditions where the load on the engine is low and the force F _G received by the exhaust valve V _E is small, the valve opening drive force F _OPEN becomes excessively large and excessive drive force is applied to the exhaust valve V _E. And the energy loss is large. Moreover, the valve opening speed becomes excessively high, which may adversely affect the performance and reliability of the engine.

The present invention has been made in view of these points, and an object thereof is to improve the configuration of a hydraulic system for driving an intake / exhaust valve to reduce the size of a switching valve and thus a valve drive device. The purpose is to reliably hold the exhaust valve open and improve the valve drive efficiency.

Another object of the present invention is to make it possible to properly set the valve opening driving force of the exhaust valve in accordance with the operating state of the engine, and to always perform the excellent valve opening operation of the exhaust valve with the optimum driving energy. To do so.

(Means for Solving the Problem) In order to achieve the above object, in the invention according to claim (1), as described above, a coil spring or an air spring for urging the intake and exhaust valves of the internal combustion engine in the valve closing direction. And hydraulic means for opening the intake / exhaust valve against the urging force of the urging means by the operating oil pressure from the pressure oil source. In a valve drive device for an internal combustion engine, which supplies and discharges the intake and exhaust valves to open and close the intake and exhaust valves, a supply system for supplying hydraulic oil from the pressure oil source to the hydraulic means or the hydraulic oil of the hydraulic means is discharged to the pressure oil source. At least one of the discharge systems is provided with a logic valve for opening and closing the supply system or the discharge system according to the pilot pressure, and the solenoid switching valve adjusts the pilot pressure of the logic valve to switch the opening / closing timing.

Further, in the invention according to claim (2), in order to appropriately set the valve opening driving force of the exhaust valve in accordance with the operating state of the engine, the exhaust valve of the internal combustion engine is set to the operating oil pressure from the pressure oil source. A valve drive device for an internal combustion engine, comprising: hydraulic means for opening a valve against the biasing force of the biasing means by means of which hydraulic oil is supplied to and discharged from a pressure oil source to open and close an exhaust valve. An operation detecting means for detecting an operating state such as a load state of the internal combustion engine or an explosive combustion state in the cylinder; and an operating oil relief at a pressure oil source according to the operating state of the internal combustion engine by receiving an output of the detecting means. And a hydraulic control means for adjusting the amount and controlling the magnitude of the hydraulic pressure of the hydraulic oil acting on the hydraulic means.

Further, in the invention according to claim (3), the above-mentioned hydraulic means is fitted to the cylinder and reciprocally movable in the cylinder in order to ensure the open / hold state of the intake / exhaust valve and improve the drive efficiency of the valve. A hydraulic cylinder having a piston that is mounted and defines the inside of the cylinder into a first pressure chamber and a second pressure chamber, and both of the first and second pressure chambers are always in communication with a pressure oil source.
Further, the pressure receiving area of the first pressure chamber of the piston is made larger than the pressure receiving area of the second pressure chamber, and the valve is opened by the difference between the two pressure receiving areas.

In that case, in order to prevent a vacuum state (cavity) from being generated in the second pressure chamber when the hydraulic oil moves from the first pressure chamber to the second pressure chamber in the valve closing stroke,
In the invention according to the above aspect, a check valve is provided which constantly communicates the first and second pressure chambers with each other through a communication passage and allows only the flow of the hydraulic oil from the first pressure chamber to the second pressure chamber in the communication passage. Set up.

(Operation) With the above configuration, in the invention according to claim (1), the pilot pressure of the logic valve is adjusted by the operation of the electromagnetic switching valve, and the lightweight and small logic valve switches the supply and discharge of the hydraulic oil to the hydraulic means. Is done. Even if the flow rate of the hydraulic oil increases, the logic valve need only be relatively small, and the electromagnetic switching valve controls the logic valve. Therefore, the hydraulic piping system can be made compact.

Further, in the invention according to claim (2), the operating state of the internal combustion engine is detected by the operation detecting means, and the hydraulic pressure control means which receives the output of the detecting means determines the pressure oil source according to the operating state of the internal combustion engine. The hydraulic oil relief amount is adjusted to variably adjust the hydraulic pressure of the hydraulic oil acting on the hydraulic means.
Therefore, the opening valve driving force of the exhaust valve appropriately corresponds to the operating state of the engine, and the driving force does not increase excessively.Therefore, in all operating states of the internal combustion engine, the exhaust valve is always driven with optimum driving energy. The valve opening operation can be favorably controlled by the valve opening drive.

Further, in the invention according to claim (3), when high-pressure hydraulic oil is supplied from the pressure oil source to the hydraulic cylinder, the piston moves due to the difference in pressure receiving area between the first pressure chamber and the second pressure chamber. The movement of the piston drives the intake / exhaust valve in the valve opening direction. At this time, since both the first pressure chamber and the second pressure chamber are constantly in communication with the pressure oil source, the hydraulic oils having the same pressure are supplied to both pressure chambers at substantially the same time. Also, during the valve open holding period, there is no pressure difference between the two pressure chambers and no hydraulic oil leaks, so the valve open holding force of the intake / exhaust valve can be kept large, and its lift is stable and constant. Can be kept at
Moreover, the energy loss is small, and the valve driving efficiency can be improved.

Further, in the invention according to claim (4), since the first pressure chamber and the second pressure chamber are always communicated with each other by the communication passage, the operation toward the second pressure chamber from the first pressure chamber in the valve closing process. The flow resistance of the oil is reduced, and the hydraulic oil smoothly flows into the second pressure chamber, which can suppress the occurrence of a vacuum state (cavity) in the second pressure chamber, and the collapse of the cavity in the subsequent valve opening stroke. It is possible to prevent the occurrence of surge pressure, abnormal valve opening operation, erosion, etc.
Moreover, since the check valve that allows only the flow of the hydraulic oil from the first pressure chamber to the second pressure chamber is provided in the communication passage, the check valve flows from the second pressure chamber to the first pressure chamber in the valve opening stroke. The flow rate of hydraulic oil does not become excessive and the valve speed does not rise,
The valve opening operation can be properly maintained.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 shows the overall configuration of a first embodiment of the present invention, in which 1 is a cylinder head of a diesel engine, and a vertical valve box fitting hole 2 is formed in the cylinder head 1 so as to penetrate therethrough. A substantially cylindrical valve box 3 is fitted and fixed in the box fitting hole 2 in an airtight manner. A hole 3a extending from one side surface to the lower surface is formed through the lower portion of the valve box 3, and a peripheral portion of the lower end opening of the hole 3a is a valve seat 4. Also, the cylinder head 1
Is a hole that communicates with the side opening of the hole 3a of the valve box 3 at one end.
1a is opened, and the other end of the hole 1a is opened to the side surface of the cylinder head 1. The hole 3a of the valve box 3 and the cylinder head 1 are opened.
The hole 1a defines an exhaust port 5 for discharging exhaust gas in the combustion chamber of the diesel engine.

An exhaust valve 6 that opens and closes an upstream end opening of the exhaust port 5 is slidably supported on the valve box 3, and the exhaust valve 6 is the valve box 3
Of the valve seat 4 (opening of the exhaust port 5) and a valve stem 6b extending upward from the valve body 6a.

An air cylinder 7 having a vertical center line is formed in the upper portion of the valve box 3, and the upper end of the valve stem 6b of the exhaust valve 6 faces the inside of the air cylinder 7, and the valve stem 6b
An air piston 8 is fixed to the upper end so that it can move integrally.
The air piston 8 defines an air chamber 9 below the piston 8 in the air cylinder 7. The air chamber 9 is communicated with the air supply source 10, and the air supply source 10
A check valve 12 that blocks the flow of air from the air supply source 10 to the air chamber 9 and seals the air chamber 9 is provided in a passage 11 that communicates the air chamber 9 with the air cylinder 9. By 7,
A biasing unit is configured to bias the exhaust valve 6 in the valve closing direction (upward) by the elastic force of the air sealed in the air chamber 9.

A hydraulic cylinder 15 as a hydraulic means for applying a driving force for driving the exhaust valve 6 to open the valve is attached to the upper portion of the valve box 3. The hydraulic cylinder 15 has a cylinder body 18 composed of a bottomed cylindrical body body 16 that is opened upward and a head cover 17 that closes the upper opening of the body body 16 in a liquid-tight manner. A rod insertion hole 16a is formed through the lower wall. Further, in the cylinder body 18, the inner space of the cylinder body 18 is provided on the upper side.
Piston 19 which is divided into pressure chamber 21 and lower second pressure chamber 22
Is reciprocally fitted, and a piston rod 20 having a diameter smaller than that of the piston 19 is integrally formed on the lower surface of the piston 19, and the first pressure chamber 21 of the piston 19 corresponds to the integral of the cross section of the piston rod 20. Is larger than the pressure receiving area of the second pressure chamber 22. The piston rod 20 is hermetically sealed in the rod insertion hole 16a of the body body 16 and slidably inserted, and the lower end of the piston rod 20 abuts the upper end of the valve stem 6b of the exhaust valve 6, which will be described later. By supplying hydraulic oil from the pressure oil source to the first pressure chamber 21, the exhaust valve 6
Is opened against the valve closing urging force of the air cylinder 7.

The first pressure chamber is provided in the body 16 of the hydraulic cylinder 15.
21 is formed with a communication passage 23 that always communicates with the second pressure chamber 22. In the communication passage 23, only the flow of hydraulic oil from the first pressure chamber 21 to the second pressure chamber 22 is allowed, and vice versa. Check valve to prevent
24 are provided.

A supply passage 25 for supplying hydraulic oil to the first pressure chamber 21 is formed in the head cover 17 of the hydraulic cylinder 15.
In the supply passage 25, a check valve 26 is provided which allows only the hydraulic oil to flow into the first pressure chamber 21 and blocks the reverse. The upstream end of the supply passage 25 is connected to the discharge side of a hydraulic oil pump 28 via a hydraulic oil supply pipe 27, and the suction side of the hydraulic oil pump 28 is connected to a hydraulic oil tank 29. An accumulator 30 for accumulating hydraulic oil having a predetermined pressure is connected in the middle of the hydraulic oil supply pipe 27, and the accumulator 30 and the hydraulic pump 28 constitute a pressure oil source.

Further, a discharge passage 32 is formed in the head cover 17 or body body 16, and the discharge passage 32 is connected to the hydraulic oil tank 29 via a hydraulic oil discharge pipe 33. Further, the discharge passage 32 has two throttles 34, 34 arranged in parallel with the first pressure chamber 21.
Through three, and in parallel with the second pressure chamber 22 three throttles 35,35,
They are communicated with each other via. Therefore, the second pressure chamber 22 is always connected to the pressure oil source together with the first pressure chamber 21 by the respective throttles 34, 35 and the discharge passage 32, and the first pressure chamber 21 and the second pressure chamber 22 of the hydraulic cylinder 15 are connected. When the hydraulic oil is supplied to the first pressure chamber 21 by the supply passage 25, the pressure receiving area of the piston 19 in the first pressure chamber 21 becomes The piston 19 is moved downward to open the exhaust valve 6 due to the difference with the pressure receiving area in the second pressure chamber 22.

A logic valve 36 is arranged in the middle of the hydraulic oil discharge pipe 33. The logic valve 36 is fitted in a valve case 37 having a valve seat 37a therein and a valve case 37 that can be seated on the valve seat 37a and can reciprocate.
A valve body 40 composed of a poppet valve that is partitioned into a hydraulic oil chamber 38 and a pilot chamber 39, which communicate with the hydraulic oil discharge pipe 33, and the pilot chamber 39, which is compressed and biases the valve body 40 in the valve closing direction. Spring 41 and a manual adjuster 42 for adjusting the maximum opening degree (maximum stroke) of the valve body 40, the pilot chamber 39 is in communication with the hydraulic oil supply pipe 27 via a pilot pipe 43, The valve body 40 is opened / closed to open / close the hydraulic oil discharge pipe 33 depending on whether or not the pilot pressure is introduced into the pilot chamber 39, and when there is no pilot pressure, the operating oil pressure of the hydraulic oil chamber 38 opens the valve body 40, while the pilot The valve body 40 is closed by pressure.

Further, the hydraulic oil supply pipe 27 is provided with the accumulator 30.
And the above described logic valve 36 between the branch to the pilot pipe 43
An electromagnetic switching valve 45 for adjusting the pilot pressure of the solenoid valve to switch the opening / closing timing of the solenoid valve is provided, and the operation of the electromagnetic switching valve 45 is controlled by the control unit 50. This electromagnetic switching valve 45 has three ports (P), (T), (A) and two switching positions for supply and discharge, and the port (P) is a hydraulic oil pump 28.
The port (A) is connected to the discharge side or the accumulator 30 of the first pressure chamber 21 of the hydraulic cylinder 15. The port (T) communicates with the hydraulic oil discharge pipe 33 between the logic valve 36 and the hydraulic oil tank 29, and when the control unit 50 positions the electromagnetic switching valve 45 at the supply position as shown in the drawing, By connecting the ports (P) and (A) to each other and closing the port (T), high-pressure hydraulic oil is supplied to the first pressure chamber 21, and the pilot pressure is supplied to the pilot chamber 39 of the logic valve 36. Supply and logic valve
36 is closed and the hydraulic oil in the first pressure chamber 21 is also supplied to the second pressure chamber 22 via the throttles 34, 35, and the piston 19 is moved downward due to the difference in pressure receiving area between the two chambers 21, 22. The exhaust valve 6 is opened by moving. On the other hand, when the electromagnetic switching valve 45 is positioned at the discharge position, the ports (T) and (A) are communicated with each other and the port (P) is closed, so that the inside of the hydraulic oil supply pipe 27 downstream of the electromagnetic switching valve 45. Of the hydraulic oil in the first pressure chamber 21 and the second pressure chamber 22 is opened by setting the pilot pressure to zero and operating the hydraulic oil in the hydraulic oil chamber 38 to open the logic valve 36. The piston 19 is moved upward while being discharged, and the exhaust valve 6 is closed.

Further, the discharge side of the hydraulic oil pump 28 is a hydraulic oil discharge pipe 33.
Is communicated with the downstream end of the via a relief pipe 46. In this relief pipe 46, a manual relief valve 47 and an electromagnetic relief valve 48 for adjusting the hydraulic oil relief amount are sequentially arranged in series from the pump 28 side, and the maximum value of the hydraulic oil pressure is increased by the manual relief valve 47. The hydraulic pressure is set by the electromagnetic relief valve 48. Then, the electromagnetic relief valve 48 is controlled by the control unit 50. The control unit 50 includes an operation detection unit 51 that detects the indicated mean effective pressure or the fuel injection amount as the operation state of the diesel engine.
The output signal of the
As shown in FIG. 2, the information from 51 is collated in advance with a map set so that an appropriate valve speed can be obtained with respect to the indicated mean effective pressure or the fuel injection amount, and the target hydraulic pressure is obtained.
The electromagnetic relief valve 48 is controlled so that the actual working oil pressure becomes the target working oil pressure. Therefore, in this embodiment, by the electromagnetic relief valve 48 and the control unit 50,
A hydraulic pressure that receives the output of the operation detection unit 51 and adjusts the hydraulic oil relief amount at the pressure oil source according to the operating state of the diesel engine to control the hydraulic pressure of the hydraulic oil that acts on the hydraulic cylinder 15. The control means 52 is configured.

Next, the operation of the above embodiment will be described.

During operation of the diesel engine, the electromagnetic switching valve 45 is switched between the supply position and the discharging position at a timing according to the engine speed under the control of the control unit 50. With the switching of the electromagnetic switching valve 45, the exhaust valve 6 Is opened and closed. That is, when the exhaust valve 6 is closed, the control unit 50 controls the electromagnetic switching valve.
When 45 is positioned in the feed position, its port (P),
The high pressure hydraulic oil from the hydraulic oil pump 28 or the accumulator 30 is supplied to the first pressure chamber 21 of the hydraulic cylinder 15 by the communication between (A) and the closing of the port (T). At the same time, the working oil pressure in the working oil supply pipe 27 is supplied as pilot pressure to the pilot chamber 39 of the logic valve 36, and the logic valve 36 is closed. As a result, the working oil in the first pressure chamber 21 is throttled. It is also supplied to the second pressure chamber 22 via the discharge passages 32 and 35 and the discharge passage 32. Since the pressure receiving area of the piston 19 in the first pressure chamber 21 is larger than the pressure receiving area in the second pressure chamber 22, the piston 19 moves downward due to the difference in the pressure receiving area against the valve closing urging force of the air cylinder 7. The piston valve 19 moves and the exhaust valve 6 is pushed down and opened by this piston 19.

At that time, when high-pressure hydraulic oil is supplied from the hydraulic oil pump 28 or the accumulator 30 to the first pressure chamber 21 of the hydraulic cylinder 15, both the first pressure chamber 21 and the second pressure chamber 22 are pressurized oil. Since the exhaust valve 6 is open, the pressures of the first pressure chamber 21 and the second pressure chamber 22 are the same, and no hydraulic oil flows between the two chambers 21 and 22 since the exhaust valve 6 is in the open state. As a result, the valve opening holding force of the exhaust valve 6 can be kept large, and the lift thereof can be kept stable and constant.

Moreover, there is no leakage of hydraulic oil from the first pressure chamber 21,
Energy loss due to the hydraulic oil pump 28 for increasing the pressure of hydraulic oil is small, and valve driving efficiency can be improved.

After that, when the exhaust valve 6 is closed, the electromagnetic switching valve 45
Are positioned in the discharge position. With the positioning of the electromagnetic switching valve 45 to the discharge position, the ports (T) and (A) communicate with each other, and the port (P) is closed, whereby the pilot pressure for the logic valve 36 disappears. Then, the throttles 34, 35 and the discharge passage 3 are provided in the first pressure chamber 21.
2 and the logic valve 3 communicating with the hydraulic oil discharge pipe 33
Since the pressure of the hydraulic oil chamber 38 of 6 is high, the valve body 40 of the logic valve 36 opens as the pilot pressure disappears, whereby the hydraulic oil passes through the logic valve 36 and the hydraulic oil tank
Return to 29. As the hydraulic oil is discharged, the exhaust valve 6 moves upward together with the piston 19 due to the valve closing urging force of the air cylinder 7. With the above, one cycle of the opening / closing operation of the exhaust valve 6 is completed, and thereafter, the same operation as described above is repeated.

At that time, the first pressure chamber 21 and the second pressure chamber 22 are connected to the communication passage 23.
Since they are communicated with each other, the flow passage resistance of the hydraulic oil flowing from the first pressure chamber 21 to the second pressure chamber 22 is small, and the hydraulic oil smoothly flows into the second pressure chamber 22. Therefore, it is possible to suppress the occurrence of a vacuum state in the second pressure chamber 22, and to generate surge pressure in the next valve opening stroke and abnormal valve opening operation,
Erosion can be prevented. Moreover,
Since the communication passage 23 is provided with the check valve 24 which allows only the flow of the hydraulic oil from the first pressure chamber 21 to the second pressure chamber 22, the check valve 24 which allows only the flow of the hydraulic oil from the first pressure chamber 21 to the second pressure chamber 22 is provided. The flow rate of the hydraulic oil flowing through the first pressure chamber 21 becomes appropriate, and the movement of the piston 19 (exhaust valve 6) is braked, so that the valve opening operation of the exhaust valve 6 can be appropriately maintained.

During operation of such a diesel engine, the indicated average effective pressure or fuel injection amount of the cylinder is detected by the operation detection unit 51, and by the control unit 50 receiving the output of this detection unit 51,
The information from the detection unit 51 is collated with a preset map (see FIG. 2) to obtain the target working oil pressure, and the electromagnetic relief valve 48 is operated so that the target working oil pressure becomes the actual working oil pressure. It is controlled to adjust the relief amount of the hydraulic oil at the pressure oil source. That is, the hydraulic pressure of the hydraulic oil is variably modulated according to the operating state of the diesel engine. Therefore, the valve-opening driving force of the exhaust valve 6 appropriately corresponds to the operating state of the diesel engine, and the driving force does not increase excessively. Therefore, in all operating states of the diesel engine, the optimum driving energy is always obtained. The exhaust valve 6 can be driven to open, and the valve drive can be controlled well.

Therefore, in this embodiment, the supply / discharge of the hydraulic oil is switched by the logic valve 36, and the electromagnetic switching valve 45 has only the function of controlling the logic valve 36, so that the hydraulic piping system can be compactly assembled. In addition, the logic valve 36 can be relatively small even if the flow rate of the hydraulic oil increases, and the logic valve 36 can be downsized.

FIG. 3 shows a second embodiment of the present invention (note that the same portions as those in FIG. 1 are designated by the same reference numerals and detailed description thereof is omitted), and instead of discharging the hydraulic oil by the logic valve 36. The supply of hydraulic oil is controlled.

That is, in this embodiment, the logic valve 36 is arranged in the middle of the hydraulic oil supply pipe 27. In addition, an electromagnetic switching valve 45 'at 4 ports and 2 positions is disposed in the middle of the hydraulic oil discharge pipe 33. The port (B) of the electromagnetic switching valve 45 'is in the discharge passage 32 of the hydraulic cylinder 15, and the port (T) is the hydraulic oil tank 29.
The port (P) is a hydraulic oil supply pipe immediately upstream of the logic valve 36.
It is connected to each 27. The port (A) communicates with the pilot chamber 39 of the logic valve 36. Then, when the control unit 50 positions the electromagnetic switching valve 45 'at the supply position (state shown in the drawing), the port (A),
(T) communicates with each other, and the ports (B) and (P) are closed together to eliminate the pilot pressure of the logic valve 36, and the logic valve 36 is opened by the hydraulic pressure from the hydraulic oil pump 28 or the accumulator 30. With solenoid switching valve 45 '
By closing the hydraulic oil discharge pipe 33 with the high pressure hydraulic oil, the high pressure hydraulic oil is supplied to the first pressure chamber 21 and the second pressure chamber 22 of the hydraulic cylinder 15.
Supply to. On the other hand, when positioned at the discharge position, the ports (A) and (P) are communicated with each other and the ports (B) and (T) are communicated with each other, and the pilot chamber 39 of the logic valve 36 is connected.
Pilot pressure acts on the logic valve 36 to close the first
By stopping the supply of hydraulic oil to the pressure chamber 21 and opening the hydraulic oil discharge pipe 33 by the electromagnetic switching valve 45 ',
The hydraulic oil is discharged from the first pressure chamber 21 and the second pressure chamber 22 to the hydraulic oil tank 29. Others are the above 1st
The configuration is similar to that of the embodiment.

Therefore, in this embodiment, when the control unit 50 positions the solenoid operated directional control valve 45 'in the supply position, the logic valve
The pilot pressure of 36 disappears, and the hydraulic pressure from the hydraulic oil pump 28 or the accumulator 30 causes the logic valve 36 to open. Further, since the hydraulic oil discharge pipe 33 is closed by the electromagnetic switching valve 45 ', the high-pressure hydraulic oil is transferred to the first cylinder of the hydraulic cylinder 15.
It is supplied to the pressure chamber 21 and the second pressure chamber 22, whereby the piston 19 moves downward and the exhaust valve 6 opens.

On the other hand, after this, when the electromagnetic switching valve 45 'is positioned at the discharge position, pilot pressure acts on the pilot chamber 39 of the logic valve 36 to close the logic valve 36, and the hydraulic oil to the first pressure chamber 21 is closed. Supply is stopped. At the same time, the solenoid switching valve
The hydraulic oil discharge pipe 33 is opened by 45 '. As a result, while the hydraulic oil in the first pressure chamber 21 and the second pressure chamber 22 is discharged to the hydraulic oil tank 29, the piston 19 causes the exhaust valve 6
Moves up with. Therefore, the same effect as that of the first embodiment can be obtained.

Further, FIG. 4 shows a third embodiment of the present invention, in which a logic valve
36 controls both the supply and discharge of hydraulic oil. That is, in this embodiment,
The hydraulic oil supply pipe 27 is provided with a supply side logic valve 36a, and the hydraulic oil discharge pipe 33 is provided with a discharge side logic valve 36b. In addition, the pilot chamber 3 of each logic valve 36a, 36b
9, 39 are hydraulic oil supply pipes 27 upstream of the logic valve 36a or hydraulic oil discharge pipes 3 downstream of the logic valve 36b via the pilot pipes 43, 43.
Connected to 3. The pilot pipes 43, 43 are provided with a 4-port 2-position solenoid switching valve 45 ″ for switching the supply of pilot pressure to the pilot chambers 39, 39 of both logic valves 36a, 36b. When the valve 45 ″ is positioned in the supply position as shown, the hydraulic pump 28
The high pressure hydraulic oil from the supply side logic valve 36b is supplied to the pilot chamber 39 to close the logic valve 36b, the pilot pressure of the supply side logic valve 36a is eliminated, and the logic valve 36a is opened to increase the high pressure. Is supplied to the first pressure chamber 21 and the second pressure chamber 22 of the hydraulic cylinder 15. On the other hand, when the electromagnetic switching valve 45 ″ is positioned at the discharge position, conversely, high-pressure hydraulic oil from the hydraulic oil pump 28 is supplied to the pilot chamber 39 of the supply side logic valve 36a to close the logic valve 36a, By removing the pilot pressure of the discharge side logic valve 36b and opening the logic valve 36b, high pressure hydraulic oil is transferred to the first pressure chamber 21 of the hydraulic cylinder 15.
And is discharged from the second pressure chamber 22.

Therefore, in this embodiment as well, in addition to being able to achieve the same effect as the above embodiment, in particular, since the logic valves 36a and 36b are used for both supply and discharge of hydraulic oil, the hydraulic system can be further improved. There is an advantage that it can be made compact.

In each of the above embodiments, the valve drive device that opens and closes the exhaust valve 6 has been described, but the present invention can be easily applied to a drive device for an intake valve. In that case, the structure of the intake valve and its peripheral portion is exactly the same as that of the exhaust valve 6,
The structure of the intake valve driving device is the same as that in each of the above-described embodiments. However, unlike the exhaust valve 6, the valve opening driving force of the intake valve may be constant for each operating state, so that the electromagnetic relief valve 48 for variably adjusting the operating hydraulic pressure, its control system, and the like can be omitted.

Further, the present invention can of course be applied to a valve drive device of an internal combustion engine other than the diesel engine.

(Effect of the Invention) As described above, according to the invention according to claim (1), in the valve drive device in which the intake and exhaust valves of the internal combustion engine are opened by hydraulic pressure, for switching between supply and discharge of hydraulic oil. Valve is a logic valve, and the pilot pressure of the logic valve is adjusted by an electromagnetic switching valve to control the opening and closing of the logic valve, so that the valve can be downsized and the amount of hydraulic oil flow and internal combustion Regardless of the type of engine, the electromagnetic switching valve can be downsized and the number thereof can be reduced, so that the hydraulic piping system can be made compact and the cost can be reduced.

Further, according to the invention of claim (2), the operating state of the internal combustion engine is detected, and the magnitude of the hydraulic pressure of the hydraulic oil for opening the exhaust valve is determined by the pressure oil source according to the operating state. By performing variable control by adjusting the relief amount of hydraulic oil, it is possible to always drive the exhaust valve with optimum drive energy regardless of the operating state of the internal combustion engine, and to perform good valve speed control thereof. .

Further, according to the invention of claim (3), the hydraulic means for driving the intake / exhaust valve to open is a hydraulic cylinder, and the first pressure chamber and the second pressure chamber on both sides of the piston are both the constant pressure oil source. Since the piston is driven by the difference in pressure receiving area between the two chambers, the pressure of both chambers remains the same while the valve is open, and the hydraulic oil from the first pressure chamber to the second pressure chamber Leakage can be eliminated, energy loss can be reduced, and valve drive efficiency can be improved. At the same time, the valve can be reliably held open to maintain its lift stable and constant. It is possible to improve functions and performances.

Further, according to the invention of claim (4), the first pressure chamber and the second pressure chamber are always communicated with each other, and the check valve is provided in the communication passage thereof, so that the second pressure is closed during the closing stroke. By eliminating the vacuum state generated in the chamber, it is possible to prevent the generation of surge pressure and erosion, suppress the valve speed in the valve opening stroke, and optimize the valve opening operation.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram showing the overall configuration thereof, and FIG. 2 is a map in which characteristics of changes in operating hydraulic pressure with respect to engine operating conditions are set. FIG. FIG. 3 is a hydraulic circuit diagram showing the overall configuration of the second embodiment. FIG. 4 is a hydraulic circuit diagram showing the overall construction of the third embodiment. FIG. 5 is a characteristic diagram showing the characteristics of the cylinder pressure and the lift amount of the exhaust valve with respect to the crank angle.
The figure is an explanatory view showing the determinants of the valve opening driving force of the exhaust valve. 6 ... Exhaust valve 7 ... Air cylinder (biasing means) 15 ... Hydraulic cylinder (hydraulic means) 18 ... Cylinder body 19 ... Piston 20 ... Piston rod 21 ... First pressure chamber 22 ... Second Pressure chamber 23 …… Communication passage 24 …… Check valve 28 …… Operating oil pump 30 …… Accumulator 36,36a, 36b …… Logic valve 45,45 ′, 45 ″ …… Solenoid switching valve 48 …… Electromagnetic relief valve 50 …… Control unit 51 …… Operation detection unit (operation detection means) 52 …… Hydraulic control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-35218 (JP, A) JP-A-60-113008 (JP, A) Practical application Sho-61-160204 (JP, U)

Claims (4)

[Claims] 1. An urging means for urging an intake / exhaust valve of an internal combustion engine in a valve closing direction, and an intake / exhaust valve opened by a working hydraulic pressure from a pressure oil source against the urging force of the urging means. A valve drive device for an internal combustion engine, comprising: hydraulic means for supplying and discharging hydraulic oil from a pressure oil source to open and close an intake / exhaust valve. A logic valve which is provided in at least one of a supply system for supplying or a discharge system for discharging the hydraulic oil of the hydraulic means to a pressure oil source, and which opens and closes the supply system or the discharge system according to the pilot pressure, and the pilot pressure of the logic valve. And a solenoid-operated switching valve for switching the opening / closing timing of the valve. 2. An urging means for urging an exhaust valve of an internal combustion engine in a valve closing direction, and a hydraulic means for opening the exhaust valve by operating hydraulic pressure from a pressure oil source against the urging force of the urging means. A valve drive device for an internal combustion engine, in which hydraulic oil is supplied to and discharged from a hydraulic oil source to open and close an exhaust valve, the operation detecting means for detecting an operating state of the internal combustion engine; And a hydraulic control means for receiving the output of the detection means and adjusting the hydraulic oil relief amount at the pressure oil source according to the operating state of the internal combustion engine to control the hydraulic pressure of the hydraulic oil acting on the hydraulic means. A valve drive device for an internal combustion engine characterized by the above. 3. The hydraulic means is composed of a hydraulic cylinder having a cylinder and a piston which is reciprocally fitted in the cylinder and has a piston for partitioning the cylinder into a first pressure chamber and a second pressure chamber. Both the first and second pressure chambers are constantly communicated with the pressure oil source, and the pressure receiving area of the piston in the first pressure chamber is set to be larger than the pressure receiving area in the second pressure chamber. The valve drive device for an internal combustion engine according to claim (1) or (2), which is configured to open the valve. 4. A check valve for always allowing communication of hydraulic oil from the first pressure chamber to the second pressure chamber is provided in the communication passage, the communication passage constantly connecting the first and second pressure chambers to each other. The valve drive device for an internal combustion engine according to claim 3, wherein the valve drive device is provided.