JPH09100706A - Hydraulic valve drive - Google Patents

Abstract

(57) Abstract: To provide a hydraulic valve drive device that guarantees synchronized opening and closing of an intake valve or an exhaust valve with high reliability under arbitrary conditions. A hydraulic drive device for driving two or more valves of an engine cylinder, particularly an intake valve of a large diesel engine, includes a hydraulic synchronous piston 12,121 and each driven valve 1.
The drive chambers 1210 and 1220 and the hydraulically driven valve pistons 13 and 13 ′ for 1,11 ′ and the plurality of valve pistons 13 and 13 ′ operate in synchronization with each other, and the synchronous piston 12 and the valves 11 and 11 ′. A braking device 124 for braking the backward movement to the initial position, and shafts 112, 11 of two or more valves 11, 11 'driven by a hydraulic drive device.
And a hydraulic device 1 that compensates for the difference between the protruding portions H and H'of 2 '.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive system for driving two or more valves of an engine cylinder, particularly an intake valve or an exhaust valve of a large diesel engine.

[0002]

2. Description of the Related Art A hydraulic valve drive replaces a mechanical drive having a lever such as a push rod used for at least one of an intake valve and an exhaust valve of an engine. It is a thing. Mechanical drives require relatively frequent readjustments due to wear of mechanical parts. Further, the hydraulic drive device can change the control time variously by a relatively simple means. This adjustment is particularly important and sensitive for an engine having a plurality of intake valves and / or exhaust valves.

When the cylinder has, for example, at least one of the intake valve and the exhaust valve, it is important to open and close the two valves in synchronization. In the hydraulic valve drive device, the valve shaft is biased by the spring against the valve piston, and the valve piston collides with the valve shaft.

Particularly in large diesel engines, slight errors occur in forming the valve seat in the cylinder cover, and more particularly in grinding the valve and valve seat. This error causes a difference in the length of the protruding portion of the valve shaft. This difference is in the range of plus / minus a few millimeters and generally belongs to the range of approximately -1 / + 3 mm. These errors are within the damper's sinking distance (Eintauchtiefe). These form a large error in closing the valve.
Certain improvements are realized by increasing manufacturing accuracy and reducing tolerances. However, the solution is unacceptable because it is expensive to implement. This is also unacceptable if a probable error in closing the valve is expected.

It is an object of the invention to provide a hydraulic valve drive which guarantees a synchronized opening and closing of the intake or exhaust valve with high reliability under any conditions.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic drive system for two or more valves of an engine cylinder, especially the intake valves of a large diesel engine, wherein a hydraulic synchronous piston and each A drive chamber for a driven valve and a hydraulically driven valve piston, a plurality of valve pistons operating in synchronization with each other, a braking device for braking the backward movement of the synchronous piston and the valve to an initial position, and a hydraulic drive device. And a hydraulic device that compensates for differences in the axial protrusions of two or more valves driven by the hydraulic drive device.
The braking device for braking the retracting movement of the synchronous piston may include a device for reducing the cross-sectional area of the return hydraulic fluid flow of the hydraulic drive. A device for reducing the cross-sectional area of flow may be formed by the drive side of the synchronous piston and the wall of the piston cylinder. The hydraulic device that compensates for the protruding portion may include a hydraulic oil supply device.

Further, the hydraulic drive system according to the present invention includes a drive piston for advancing and retracting the synchronous piston, a retreating operation of the drive piston to an initial position, and a cylinder of the drive piston which is carried out in association therewith. And a hydraulic switching device that delays the backward movement of the synchronous piston to the initial position as compared with the backflow of the hydraulic oil into the cylinder space formed in the.

The hydraulic piston pump for operating the hydraulic drive system of the present invention comprises a hydraulic line system for transporting hydraulic oil back and forth between the piston pump and the hydraulic drive system, and the hydraulic oil pump and cylinder. A main conduit having a one-way valve for preventing backflow into the inside, a bypass conduit having a switchable valve that bypasses the one-way valve in the main conduit, and a one-way valve in the main conduit, And a second supply and return line for supplying hydraulic oil through the cylinder wall of the hydraulic piston pump into the cylinder space of the piston pump. Alternatively, the hydraulic piston pump of the present invention may be held in an open position with a hydraulic line system that transports hydraulic fluid back and forth between the piston pump and the hydraulic drive, In addition, by bypassing the one-way valve with a one-way valve that prevents the hydraulic oil from flowing back into the pump cylinder in the unblocked state, and by bypassing the one-way valve in the main pipe with the hydraulic oil, A second supply and return line may be provided for feeding through the cylinder wall into the cylinder space of the piston pump.

Further, the hydraulic piston pump of the present invention supplies hydraulic oil to the reservoir, and further, a supply device for receiving the hydraulic oil from the reservoir and preventing the hydraulic oil from returning to the reservoir. It may have a supply line with a one-way valve and a supply and return line that bypasses the one-way valve of the supply line and supplies hydraulic oil into the cylinder of the piston pump near bottom dead center. Of these, the supply pipeline supplies the working oil into the cylinder space near the top dead center. Further, the supply and return pipes supply the hydraulic oil into the cylinder space near the bottom dead center. Furthermore, the second supply and return line of the hydraulic drive supplies hydraulic oil into the cylinder at a height between top dead center and bottom dead center.

In addition, the large diesel engine according to the invention comprises the hydraulic drive of the invention for driving the intake or exhaust valves. By using a hydraulic drive according to the present invention, more than one valve can be driven synchronously. The valve drives are independent of each other so that the difference in the frictional resistance of each valve does not affect the valve synchronization. Differences in the protruding portion of the valve stem are compensated. Furthermore, changes in the protruding portion of the valve stem that occur during operation are continuously compensated. The braking device ensures that the synchronous piston and the valve of the hydraulic drive rest against the valve seat under braking. As a result, it is possible to avoid high stress that is intermittently formed by impact when the braking is not performed. This prolongs valve seat and valve life. Furthermore,
Pitting, i.e. formation of pits in the sealing surface of the valve, is prevented by cushioning the impact. Moreover, the hydraulic drive allows a temporary delay of the valve closing process in a certain range.

[0011]

1 shows a hydraulic drive according to the invention for two intake valves 11, 11 'of a diesel engine, for example. The valve seats 111, 111 '(only a portion is shown) are machined in the cylinder cover 10. The two shafts 112, 112 'have collars 113, 11
3 ′ respectively. Furthermore, the two shafts 112, 11
The two ends of each valve spring 115,115 'arranged on the 2'is the collar 113,113' and the cylinder cover 1
Each is biased against 0.

The hydraulic drive for the valves 11, 11 ′ has a synchronizing piston 12. The synchronizing piston 12 is formed as a stepped piston. Step 12
1, 122 are guided in the chambers 1210, 1220, respectively. When the synchronous piston 12 moves, both chambers 1210, 12
Within 20 the capacitance is varied equally. When it becomes possible to return the hydraulic oil from the cylinder space 120 to the hydraulic piston pump 31 through the line 1200, the valve springs 115 and 115 ′ are the valve pistons 13 and 13 ′ and the valve pistons 13 and 13 ′. The synchronous piston 12 is pressed toward the initial position via the hydraulic connection line of the. It may be impossible to push the synchronous piston 12 to the initial position due to fluid loss (gap). However, the spring 1211 located in the chamber 1210 can fully bias the synchronizing piston 12 to its initial position.

The synchronous piston 12 is a base 123 of the cylinder.
In order to prevent a collision with the
The end of the cylinder with respect to and the end of the synchronous piston 12 cooperate to form a damper 124 as a braking device. The damper 124 reduces the backflow rate per unit time by blocking the backflow of hydraulic oil into the pipe 1200. Cylinder base 12 by braking the synchronous piston 12
The shock on the valve 3 is dampened by braking the valves 11 and 11 'and also the shock applied to the valve seats 111 and 111'.

The two valve pistons 13, 13 'are of the same size and the active areas 125, 1 of the synchronizing piston 12 are
If 25 'each have the same size, the two valve pistons 13, 13' will move the same distance as they move in a given passage. As a result, the valve shafts 112, 112 'move synchronously. As used herein, the term "synchronous" refers to the same distance moving equally at the same time.

Of course, the synchronization piston and valve piston may have other configurations. For example, the active regions 125 and 125 'of the synchronizing piston 12 may be formed in different sizes. In this case, a requirement to be considered is to match the displacement of the chambers 1210 and 1220 of the synchronous piston 12 with the displacement of the cylinders 130 and 130 'of the valve pistons 13 and 13', respectively. This alignment is achieved by each valve piston 13, 13 'and valve 11, 11'
Are adjusted to have the same stroke.

In order to compensate the loss of hydraulic oil due to leakage, the hydraulic oil is supplied to two supply lines 114 and 11 as a supply device.
It is supplied to the hydraulic circuit through 4 '. Backflow of hydraulic oil is prevented by the one-way valves 1141 and 1141 ′. By supplying hydraulic oil into the system, the valve piston 1
3, 13 'always abuts on the ends of the valve shafts 112, 112' regardless of the difference between the protruding portions (distance from the valve shaft ends to the cylinder cover) H, H'of the valve shafts 112, 112 '. It will be.

Another possibility of compensating for the loss of hydraulic fluid due to leakage is the pressure chamber 120 and the chambers 1210, 1220.
It can be mentioned that the loss amount is supplied through a bore in the synchronizing piston 12 connecting the. In order to keep the effect between the chambers small enough, choke openings are formed in the channels connecting the chambers. In another configuration, a bore for supplying the hydraulic oil to compensate for the loss of the hydraulic oil due to leakage is formed through the housing to each chamber.

FIG. 2 shows an example plot of valve opening and closing as a function of crankshaft angle in a four-stroke diesel engine. The valve opens at crankshaft angles in the range of about 180-250 degrees. After closing the valves, the valves 11, 11 'are maintained in their rest position, i.e. in the closed position R, until they are opened again. Therefore, the valve closure continues within the crankshaft angle range of 470-540 degrees. If the valves 11, 11 'are arranged in the rest position R, the replenishment of hydraulic oil into the system takes place via the supply line.

The pipeline system 3 and the hydraulic piston pump 31 as the hydraulic switching device shown in FIG. 3 are used to drive the synchronous piston and the like of the hydraulic drive device of FIG. The arrangement includes a piston pump 31 which supplies hydraulic oil. The main line 32 having the one-way valve 321 is a piston pump 31.
From the drive device shown in FIG. Bypass line 3
3 bypasses the one-way valve 321 and supplies hydraulic oil into the cylinder space 310 of the piston pump 31. The bypass line 34 bypasses the one-way valve 321.
Both ends thereof communicate with the main conduit 32. A switchable valve 341 that can be switched by the compressed air communication unit 342 or the like.
Is incorporated in the bypass line 34.

The switchable valve 341 may be any one of a hydraulic valve, a solenoid valve and other switchable valves. If the one-way valve 321 in the main line 32 can be closed in the open position, the bypass line 34 can be omitted.

The supply line 35 may be used to supply hydraulic fluid that has leaked from the hydraulic system due to a leak. Supply line 3
5 has a one-way valve 351. Excess hydraulic oil may be returned to the supply line 35 connected to the hydraulic oil reservoir through a bypass line 352 as a supply and return line. The piston 311 of the piston pump 31 can be driven by a cam (not shown) or the like.

A hydraulic piston, together with the pipeline system 3,
The function and operation mode of the pump 31 will be described in detail below. It is assumed that the control pressure in the control line 342 is switched on, that is, the bypass line 34 is opened. In the delivery stroke of the pump piston 311, the following operations are performed. After closing the bore 3512 by the piston 311, hydraulic fluid is supplied to the hydraulic drive through the passages 33, 32 to operate the valve. After that, the bore 332, which is the connecting portion of the bypass conduit 33, is closed, and the hydraulic fluid flows through the main conduit 32 and the bypass conduit 34.

In the downward stroke of the pump piston 311, the following operations are performed. The main line 32 is closed by the one-way valve 321. Bypass 33 is still closed by piston 311 located on bore 332. However, the bypass 34 is open and the closing movement of the synchronous piston follows the movement of the piston 311. This operation is illustrated by the solid curve 41 located at the top of FIG.

Next, assume that the control pressure in the control line 342 is switched off, that is, the bypass line 34 is closed. In the delivery stroke of the pump piston 311, the following operation is performed. Bore 3512 has piston 3
After being closed by 11, hydraulic fluid is routed through passages 33, 32 to the hydraulic drive to actuate the valves. After that, the bore 33 that is the connection portion of the bypass conduit 33
2 is closed by the piston 311 and the flow of hydraulic oil is continued through the passage 32.

In the downward stroke of the pump piston 311, the following operation is performed. The main line 32 is closed by a one-way valve. Bypass conduit 33 is bore 332
It is closed by an upper piston 311.
Further, the bypass line 34 is closed. As a result,
The driven hydraulic synchronous piston 121 does not follow the operation of the piston 311 as long as the bore 332 that is the connection portion to the bypass conduit 33 is closed by the piston 311. Therefore, in the initial stage of the downward movement of the piston 311, the situation where the synchronous piston 12 moves and the valve is opened (see FIG. 1) does not occur. The change in the closing curve is indicated by the dashed line 42 at the top of FIG.

The increase in the system volume is dealt with by supplying hydraulic oil through a supply line 35 serving as a supply device. In general, low pressures in the supply line, for example 3 to 10 bar, are sufficient. At the same time that the piston 311 opens the bore 332, a reverse flow of hydraulic oil from the hydraulic drive device into the cylinder space 310 is formed in the bypass conduit 33. Then, the valve closing operation is started, and the valve closing operation is performed by the piston 3
It is controlled by the downward movement of 11. Bore 3512
Is the cylinder space 3 near the bottom dead center of the piston 311.
It opens in 10. At this point, the closing operation continues uncontrolled. The damper 124 on the synchronous piston 12 operates to avoid the formation of a large impact by the valve (see FIG. 1).

In FIG. 4, the closing action of the valve is indicated by the dashed line 42. The curve 40 drawn at the bottom of FIG. 4 shows the change in stroke of the piston 311 in the configuration of FIG. The point 44 on the lower curve 40 showing the movement of the piston 311 as a function of crankshaft angle is at the point when the piston 311 opens the bore 332 as it descends, allowing backflow of hydraulic oil. The position of the piston 311 is shown. If the closing process of the valves 11, 11 'is started before the piston reaches the position 44, the valve 341 is opened.

The hydraulic drive system 1 is suitable for two or more valves of an engine cylinder, in particular intake valves 11, 11 'or exhaust valves of a large diesel engine. The hydraulic synchronous piston 12,121 has one drive chamber 1210,1220 for one driven valve 11,11 '. Drive room 12
10, 1220 are the valve pistons 13, 1 of the valves 11, 11 '
Drive each 3 '. At this time, the valve pistons 13, 1
3'moves in the same stroke in synchronization. Braking device 1
24 damps the return movement of the synchronizing piston 12 to its initial position. By using the hydraulic drive device 1, the valve 1
The difference between the protrusions H, H'of the shafts 112, 112 'of 1, 11' is compensated.

Although the present invention has been described in detail based on the preferred embodiments, hydraulic sources other than the hydraulic piston pump 31 are also suitable for use in the hydraulic drive system of the present invention. For example, “Common rail system”
A hydraulic high pressure system referred to as can be used. In a shared rail system, high pressure fluid is supplied from a high pressure fluid system to a hydraulic drive through an electromagnetically controlled valve. Additionally, the return fluid from the hydraulic drive is returned to the reservoir of the high pressure fluid system. When using a shared rail system, it is advantageous to place the braking device on the front side, i.e. the side of the step of the synchronous piston, to mitigate the impact on the cylinder cover. In another construction of the shared rail system, the braking device of the valve piston may be arranged in the direction of opening the valve.

[0030]

According to the present invention, it is possible to ensure the synchronized opening and closing of the intake valve or the exhaust valve with high reliability under any condition.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a hydraulic drive device of the present invention that drives two valves.

FIG. 2 is a diagram showing valve position as a function of crankshaft angle for a four-stroke engine.

FIG. 3 is a diagram showing a hydraulic line system and a hydraulic piston pump for driving the hydraulic drive system of the present invention.

FIG. 4 is a diagram showing valve position as a function of crankshaft angle (upper curve) and a diagram showing piston position of a piston pump as a function of cam angle (lower curve).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydraulic drive device, 3 ... Pipe line system as a hydraulic switching device, 11, 11 '... Valve, 12, 121 ... Hydraulic synchronous piston, 13, 13' ... Hydraulic drive valve piston, 31
... hydraulic piston pump, 32 ... main line, 33 ... second
Bypass line as a supply and return line for the gas, 34 ... Bypass line, 35 ... Supply line as a supply device, 112,
112 '... Valve shaft, 114, 114' ... Supply line as hydraulic oil supply device, 124 ... Damper as braking device, 311 ... Drive piston, 310 ... Cylinder space of cylinder, 321 ... One-way valve, 332 ... bore on cylinder wall located between top dead center and bottom dead center, 341 ... switchable valve, 351 ... one way valve, 352 ... supply and return lines,
1210, 1220 ... Drive room.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Genil Patrick Switzerland Zecher −8472 Zeuitzach Weidstraße 6 (72) Inventor Wildi Rim Turan Switzerland Zecher −8408 Wintertool Langwiesenstraße 10

Claims (10)

[Claims] 1. Two or more valves (1) of an engine cylinder
1, 11 '), in particular a hydraulic drive (1) for an intake valve of a large diesel engine, comprising a hydraulic synchronous piston (12, 121) and each driven valve (11, 1).
1 '), the drive chambers (1210, 1220) and the hydraulically driven valve pistons (13, 13') and the plurality of valve pistons (13, 13 ') operate in synchronization with each other; 12, 121) and valve (11,
11 ') a braking device (124) for braking the backward movement of the valve to the initial position, and the shafts (112, 11') of two or more valves (11, 11 ') driven by the hydraulic drive device (1).
2 ') a hydraulic drive (1) for compensating for the difference between the protruding portions (H, H'). 2. The hydraulic system according to claim 1, wherein the braking device for braking the backward movement of the synchronous piston (12) includes a device (124) for reducing the cross-sectional area of the flow of the return hydraulic fluid of the hydraulic drive device. Drive. 3. A device (1) for reducing the cross-sectional area of the flow.
24) Formed by the drive side of the synchronous piston (121) and the wall of the piston cylinder.
The hydraulic drive device according to. 4. A hydraulic drive system according to claim 1, wherein the hydraulic device for compensating for the protrusions (H, H ′) has a hydraulic oil supply device (114, 114 ′). 5. A drive piston (311) for advancing and retracting a synchronous piston of the hydraulic drive system according to claim 1, and a drive piston (311) for moving the drive piston (311) to an initial position. The retreating operation and the reciprocating operation of the synchronous piston (12) to the initial position as compared with the backward movement of the hydraulic oil into the cylinder space (310) formed in the cylinder of the drive piston (311). Hydraulic drive device having a hydraulic switching device (3) for delaying. 6. A hydraulic piston pump (31) for operating the hydraulic drive system according to any one of claims 1 to 5, comprising: a piston pump (31) and the hydraulic drive system. Hydraulic line system for transporting hydraulic oil back and forth in
3, 34, 35, 352) and a main line (32) with a one-way valve (321) that prevents hydraulic oil from flowing back into the pump cylinder (310).
And a bypass line (34) having a switchable valve (341) bypassing the one-way valve (321) in the main line (32)
And bypassing the one-way valve (321) in the main line (32),
A hydraulic pressure having a second supply and return line (33) for supplying hydraulic oil into the cylinder space (310) of the piston pump (31) through the cylinder wall (332) of the hydraulic piston pump (31) Type piston pump. 7. A hydraulic piston pump (31) for operating the hydraulic drive device according to any one of claims 1 to 5, comprising: a piston pump (31) and the hydraulic drive device. Hydraulic line system for transporting hydraulic oil back and forth in
3, 35, 352) and a one-way valve (321) that can be selectively retained in the open position and that prevents hydraulic fluid from flowing back into the pump cylinder (310) in the unblocked state. Bypassing the main conduit (32) and the one-way valve (321) in the main conduit (32),
A hydraulic pressure having a second supply and return line (33) for supplying hydraulic oil into the cylinder space (310) of the piston pump (31) through the cylinder wall (332) of the hydraulic piston pump (31) Type piston pump. 8. A supply device (3) for supplying hydraulic oil to a reservoir and further receiving the hydraulic oil from the reservoir.
5,352) and a one-way valve (3) that prevents hydraulic oil from returning to the reservoir.
Bypassing the supply line (35) having 51) and the one-way valve (351) of the supply line (35),
In addition, the hydraulic oil is supplied to the piston pump (3
Hydraulic piston pump according to claim 6 or 7, having a supply and return line (352) for feeding into the cylinder (310, 3512) of 1). 9. The supply pipe (35) supplies hydraulic oil into the cylinder space (310) near the top dead center, and the supply and return pipes (352, 3512) lower the hydraulic oil. Supply into the cylinder space (310) near the point, and a second supply and return line (33) of the hydraulic drive.
9. The hydraulic piston pump of claim 8 including supplying hydraulic fluid into the cylinder (310) at a height (332) between top dead center and bottom dead center. 10. A large diesel engine having a hydraulic drive (1) for an intake valve (11, 11 ') or an exhaust valve according to any one of claims 1 to 9.