JPS608322B2 - Diesel engine valve timing change device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve operating system for opening and closing intake and exhaust valves of internal combustion engines, particularly diesel engines.・
The purpose is to automatically change the opening and closing timing of the exhaust valve to keep the diesel engine in the best operating condition at all times.

Normally, the opening angle and opening/closing timing of the intake and exhaust valves installed in a diesel engine are set to the optimal conditions within a certain range according to the engine's output and rotation speed, but as the engine output increases, As weekly wages become higher, the compression ratio is set low to suppress explosion pressure during high-load operation, and at the same time, the intake and exhaust valves are open at the same time to increase the scavenging effect and suppress the heat load (overlap period). It is necessary to take a large value.

On the other hand, during low-load operation that is close to no weekly pay, setting the compression ratio high, increasing the explosion pressure, and shortening the overlap period to fully utilize the expansion pressure is the best way to keep the engine in the best operating condition. This is desirable. For example, when the load is high, the intake valve opens at position A, approximately 800 degrees before the piston's top dead center TDC, as shown by the solid line in Figure 1a, closes at position B, approximately 450 degrees after the bottom dead center BDC, and the exhaust valve As shown by the broken line, opens at position C, approximately 50o in front of bottom dead center BDC,
The intake valve is set to close at position D, approximately 60 degrees after top dead center TDC, the compression ratio is set low, and at low load, the intake valve is closed at position A', approximately 20 degrees before top dead center TDC, as shown in Figure 1b. Open,
Close the exhaust valve at position B' immediately after bottom dead center BDC, and return the exhaust valve to bottom dead center B.
Opens at position C' about 30o before DC, about 2 after top dead center TDC
It is desirable to set it so that it closes at position D' of 0o and to set the compression ratio to be large. Therefore, with a conventional single-function valve train, an engine whose valve opening/closing timing is set to achieve the best performance under high loads may suffer from poor combustion due to an insufficient compression ratio at low loads that are close to those without weekly wages. Excessive overlap period causes problems such as fouling due to exhaust gas blowing back into the explosion chamber and the intake system, and poor exhaust color and startup failure due to decreases in compression and piston temperatures.
Conventionally, to eliminate these drawbacks, the hydraulic pressure generated by a fluid pump driven by an engine is supplied to the intake/exhaust valve opening device through a switching valve, and the switching of the switching valve is performed using a timing cam as the drive source. A device in which a mechanism for adjusting the opening and closing timing of the valve is incorporated into the switching valve actuating device is known from Jitsoseki No. 50-59808, but this device uses a fluid pump to constantly operate at high pressure. This requires a large amount of energy loss, and the use of fluid pumps, switching valves, etc. makes the entire device complicated and expensive.Furthermore, the valve must be opened and closed during the cam lift upward stroke. Therefore, the cam lift rise curve had to be made gentle, and as a result, the valve opened slowly, and the valve opening area was not sufficiently large, so it was still not sufficient.

As another conventional example, British Patent No. 1224168 discloses a pump having a piston that reciprocates in the axial direction in cooperation with a cam, and a plunger that is actuated by hydraulic pressure generated by this pump to drive a valve. This disclosure discloses a valve timing changing device that can change valve timing by rotating a piston.

However, in this conventional device, there is only one hydraulic control hole, and control notches are provided at both ends of one land of the piston in the horizontal direction, so the piston is lowered before the end of its upward stroke. The notch on the side opens the hydraulic control hole and releases the hydraulic pressure acting on the plunger. Therefore, the valve closing timing is not controlled at all by the downward lift of the cam, and even though the piston is reciprocated up and down by the cam, the opening and closing of the valve is controlled only by the cam in the upward stroke of the piston (one side). Therefore, the piston has many unnecessary operations, which makes it difficult to increase the valve opening area and also makes it difficult to accurately set the valve closing timing. This invention solves the above drawbacks and inconveniences of conventional devices by controlling the valve timing using a cam during the upward stroke of the piston, and controlling the valve closing timing during the downward stroke of the piston using the cam. The present invention aims to provide an engine valve timing changing device.

The structure of the present invention will be explained below according to the embodiments shown in the drawings. In Figures 2 and 3, 1 is a camshaft, 2 is a timing cam attached to the camshaft 1,
3 is a bed that can be moved up and down by timing cam 2, 4
Reference numeral denotes a night bed guide which is fixed to the cylinder block 5 with iron fittings, and the night bed 3 slides inside this night bed guide 4.

8 is the main body of the device which is fixed upright on the evening bed guide 4;
A drive cylinder 7 is provided inside in the axial direction, an actuation cylinder 8 interlocked with the agitation cylinder is provided at the top, and an oil supply portion 9 is provided at the upper side of the drive cylinder 7.

1. A drive piston is slidably inserted into the drive cylinder 7, and its upper end surface forms a valve-opening control edge 13 oblique to the marquee, and a hydraulic pressure generating chamber is provided in the drive cylinder. define.

The drive piston 10 further has a valve closing control green 12 spaced apart from the valve closing control edge 13 in the axial direction via a cutout groove 11 . The valve closing control green 12 is the valve opening control edge 1 relative to the axis.
It is tilted in a different direction than 3. Notch groove 11' oil passage 1
It communicates with the above-mentioned hydraulic pressure generation chamber via 4. The lower end of the drive piston 10 is connected by a connecting frame 15 and a spring 16, and is axially interlocked with the evening bed 3 and rotatable in the circumferential direction. A valve-closing control hole 17 that is opened and closed by the valve-closing control green 12 and a valve-opening control hole 18 that is opened and closed by the valve-opening control edge 13 are formed on the side wall of the drive cylinder 7 to face each other. be. Reference numeral 19 denotes a pinion cylinder which is slidably fitted to the outer circumferential surface of the drive cylinder 7, and whose lower end is locked to the lower flange 11a of the drive piston 10 so as not to impede the movement of the drive piston 10 in the axial direction. , which restricts rotation in the cylindrical direction and meshes with a rack 20 provided on the device main body 6, and the rotation of this causes the pinion cylinder 19 and the drive piston 10 to rotate.

Reference numeral 21 denotes an oil supply hole for supplying hydraulic oil to the drive cylinder '7}, which supplies oil to the upper part of the drive cylinder 7 through the check valve 22 and the oil passage 23, and as the drive piston 10 rises, the check valve 2
4 and oil passage 25 to the working cylinder 8 side.

Further, the valve closing control hole 17 and the oil passage 25 are connected to a branch oil passage 26.
When the drive piston 10 moves up and down with the valve opening control hole 17 open, the oil in the oil passage 25 is returned to the drive cylinder 7 via the branch oil passage 26. The valve opening control hole 18 and the oil supply hole 21 are connected to each other by an oil passage 27,
When the drive piston 10 moves up and down with the valve opening control hole 18 open, the oil in the drive cylinder 7 is returned to the oil supply side via the oil passage 27. Reference numeral 28 denotes an operating piston that is slidably disposed within the operating sill 8 and supports the spherical end of the push rod 29, and rises in accordance with the amount of oil supplied from the oil passage 25 as the drive piston 10 rises. .

301 A valve arm that can be swung by a push rod 29, 3
1 is a valve that is opened and closed by a valve arm 30; and 32 is a valve spring.

Reference numeral 33 denotes an oil relief groove provided in the operating cylinder 8. When the operating piston 28 rises by a predetermined amount, the supplied oil is released and discharged from the oil outlet 34 to the outside to regulate the amount of rise of the operating piston 28. 31 is operated for a constant stroke. 5 The pressure regulating valve regulates the leakage oil from the oil outlet 34 of the working cylinder 8 to a constant pressure, prevents a sudden drop in the oil pressure in the oil passage 25, and prevents the valve from the working piston 28 to the valve 31. Prevents hunting in the drive system.

51 is a stopper for the actuating piston 28.

To explain the operation of the above configuration, in the state shown in FIG. It is located opposite to the time control hole 18, and is set to the valve timing during high load.

In this state, when the evening bed 3 is pushed up by the timing cam 2, the driving piston 10 connected to the evening bed 3 also rises, and the valve closing control edge 12 and the valve opening control edge 13 respectively control the valves. The closing control hole 17 and the valve opening control hole 18 are closed, and the oil in the drive cylinder 7 is supplied to the working cylinder chamber of the working cylinder 8 via the check valve 24 and the oil passage 25, and the working piston 2
8 is raised, the valve 31 is opened via the push rod 29 and the valve arm 30, and the working piston 28 reaches a predetermined position and the oil relief groove 33 is opened. The oil is discharged from the groove 33 to the outside through the outlet 34, and the working piston 28 does not rise any further, and the valve 3
1 is kept constant. At this time, leakage oil from the oil outlet 34 is regulated to a constant pressure by the pressure regulating valve 501, so hunting of the operating piston 28 and the valve 31 of the valve drive system is prevented. In other words, without the pressure regulating valve 50, when the actuating piston 28 reaches a predetermined position and the oil is released toward the oil relief groove 33, the oil pressure in the oil passage 25 will be ok/kg.
The valve spring 32 causes the operating piston to close the oil relief groove 33 and is pushed back until the oil pressure returns to the predetermined pressure, causing the valve 31 to return. However, since the oil pressure of the leaked oil is kept constant through the pressure regulating valve 501, no oil pressure drop occurs, the actuating piston 28 is not pushed back, and is kept at a constant position, so that the valve 31 does not swing. Note that the upper limit position of the operating piston is regulated by a stopper 51. Then, the drive piston 11 completes its upward movement as shown by the dashed line in FIG. 2, after which the timing cam 2 rotates, the tab 3 and the drive piston 10 are pushed down, and begin to descend. Then, the upward force on the actuating piston 28 disappears, and the downward force is applied by the valve spring 32. However, until the driving piston 10 descends to a predetermined position, the valve closing control hole 17 is closed by the valve closing control edge 12, and the oil in the oil passage 25 has no place to escape, and the operating piston 28 Only the drive piston 10 descends without descending,
Valve 31 is kept open. and drive piston 10
When the valve closing control hole 17 is opened as the valve is lowered, the oil passage 2
The oil in 5 is connected to the oil passage 26, the valve closing control hole 17, the notch groove 11,
The working piston 28 descends and the valve 31 is closed. During this operation, when the valve is engaged, the valve opening control hole 17 and the valve opening control hole 18 are
are closed by the valve closing control edge 17 and the valve opening control edge 18, respectively, and as the driving piston io rises, the cylinder 7
All the oil inside is supplied to the working cylinder 8, and the working piston 28 immediately follows and rises, opening the valve 31. Also, when the valve is closed, the drive piston 10 is initially moved to the control hole 17 when the valve is closed.
Since the actuating piston 28 is stopped, the valve 31 can be maintained in the open state, and during this time, the check valve 22 and the oil passage 2 are connected to the drive cylinder 7.
3, oil is supplied from the oil supply hole 21 and does not interfere with the lowering of the drive piston IQ.The operating characteristics of the drive piston 10 and the working piston 28 at this high load are shown in Fig. 4. As shown in FIG.
The piston follows the zero tone and rises, then stops rising at a predetermined position and moves in parallel. When descending, the drive piston IQ' begins to descend after a predetermined time delay. Finally, it finishes descending at the same time. To explain the operation, first, as shown in Fig. 3, the rack 20
The driving piston 10 is rotated through the pinion barrel turtle 9.
is rotated by a predetermined angle so that the lower end sides of the valve open control edge 12 and the valve open control edge blade 3 are opposed to the valve close control hole 17 and the valve open control hole 8, respectively. Set.

In this state, when the evening valve 3 is pushed up by the timing cam 2, the drive piston turtle Q also rises together with it, and after a predetermined delay, the valve closing control hole turtle 7 and the valve opening control hole 18 change to the valve closing control hole. 12 and a control edge 13 when the valve is open. Therefore,
When the drive piston IQ starts to rise, the oil in the drive cylinder 7 is returned to the oil supply side through the valve open control hole 18 and the oil passage 27, and the oil in the drive cylinder 7 is not supplied to the actuation cylinder 8.
The working piston 28 does not rise. And valve closing control hole 1
7 and the valve opening control hole 18 are closed, the oil in the drive cylinder 7 is supplied to the actuation cylinder 8 via the check valve 24 and the oil passage 25, causing the actuation piston 28 to rise. 30 to open the valve 31. Then, when the timing cam 2 rotates further and the force pushing up the bed 3 is removed, the spring 16 closes the bed 3.
Then, the driving piston 10 is pushed down and begins to descend, the upward force on the working piston 28 disappears, and a downward force is applied to the working piston 28 by the valve spring 32. When the driving piston 10 begins to descend, the valve closing control edge 2 and the valve opening control green 13 immediately open the valve closing control hole 17 and the valve opening control hole 18 to prevent oil leakage as the actuating piston 28 descends. Road 25
Branch oil in the oil passage 26, control hole 7 when the valve is closed, and oil passage 1.
4 into the drive cylinder 7, the drive piston IQ and the working piston 28 both descend and close the valve 31. After the valve 31 closes, only the drive piston 0 descends. At time t, the drive piston 10
Even if the valve opening temperature rises, while the valve opening control hole blade 8 is open, the oil in the drive cylinder 7 is released and the supply to the actuation cylinder 8 is temporarily stopped, thereby delaying the start of operation of the actuation piston 28. I can do it. Furthermore, when the valve is closed, the valve closing control hole 17 is opened at the same time as the drive piston 10 is lowered, and the oil passage 2 is opened.
The oil in the drive cylinder 5 can be immediately returned to the drive cylinder 7, and the operating piston 28 can be immediately lowered to quickly close the valve 3.
0 and the operating piston 28, as shown in FIG. 4, the drive piston Kamegawa operates in conjunction with the timing cam 2 as shown by the dashed line 35 as in the case of high load, and the operating piston 28 operates as shown by the dashed line 35. As shown at 37, the drive piston 10
Even if it is raised after a predetermined time delay and moved in parallel at a predetermined position, it descends substantially at the same time as the drive piston 10 descends. Therefore, the valve 31 opens later and closes earlier when the load is low than when the load is high. and rotate the drive piston 10 to appropriately set the positional relationship between the valve-closing control edge vane 2 and the valve-closing control hole 17 and the positional relationship between the valve-opening control edge 13 and the valve-opening control hole 18. This will allow you to adjust the timing of opening and closing at a predetermined time.

FIG. 6 is a drawing showing another embodiment, in which the push rod 29 and the valve arm 30 are eliminated, an operating cylinder 38 is provided above the valve 31, and this and the oil passage 25 are connected by a connecting pipe 39. The actuating piston 40 and the upper end of the valve 31 are connected.

The mother river oil relief groove, 42, is an oil outlet. Note that the same reference numerals as in FIG. 2 indicate the same parts, and the operation is the same as in the above embodiment. As explained above, this invention consists of a driving cylinder having a turbulent piston that reciprocates in the direction of the hoe in cooperation with a tabet, and an operating cylinder having an operating piston that operates by hydraulic pressure generated by the driving piston to drive a valve. In a valve timing changing device that can change valve timing by rotating a driving piston, the working cylinder has a working cylinder chamber that receives pressurized oil from the driving cylinder and a working cylinder chamber that receives pressurized oil from the driving cylinder and drains excess oil. an oil supply hole through which the drive cylinder is supplied with pressurized oil; a valve opening control hole that is connected to the oil supply hole and opens into the oil pressure generation chamber; An oil passage extending between the hole and the hydraulic pressure generation chamber and equipped with a check valve that only allows oil to flow toward the hydraulic pressure generation chamber; an oil passage provided with a check valve that only allows oil to flow toward The valve opening control green which faces the hydraulic pressure generation chamber of the cylinder and is inclined with respect to the axis is also another land which is separated from the land on the valve opening control edge in the rut direction via a notch groove and which is inclined with respect to the axis. a valve closing control edge and an oil passage connecting the notch groove and the oil pressure generation chamber, and the direction of inclination of the valve opening control green and the valve closing control green is adjusted when the valve is opened. The timing of closing the valve and the valve is changed by associating the opening and closing timing with the control hole and the valve-closing control hole so that they are in the same relational direction, and by rotating the driving piston in accordance with the load of the diesel engine. By doing so, it is possible to adjust the valve timing of the diesel engine to be optimal both at high load and low load by rotating and adjusting the turbulence piston as appropriate. A separate pump is not required for the valve's operating hydraulic pressure, and the drive cylinder itself serves as both the pump and the switching valve, making the device simple and inexpensive.Also, the valve's operating hydraulic pressure is generated intermittently only during operation. Therefore, energy loss is extremely reasonable and fuel efficiency can be achieved.Furthermore, since the opening timing and closing timing of the L valve are controlled separately for the upstroke and downstroke of the drive piston, the wasted operation of the drive piston is reduced. death,
This means that both reciprocating motions are effectively utilized, which not only guarantees reliable opening and closing of the valve at the set timing, but also allows for a steeper cam lift rise curve and faster valve opening speed. This makes it easy to set and allows for a sufficient valve opening area.

[Brief explanation of the drawing]

Figures a and b are diagrams showing valve timing suitable for high-load operation and low-load operation of a general diesel engine, and Figure 2 is a sectional view showing the overall configuration of the valve timing changing device according to the present invention. FIG. 3 is a sectional view of the main part showing the position of the driving piston at low load, FIG. 4 is a graph showing the operating characteristics of the driving piston and the working piston, and FIG. 5 is a sectional view showing another embodiment. . 7... Drive cylinder, 8... Actuation cylinder, 1
Vi... Drive piston! 2... Control green when valve is closed, 13... Control edge when valve is open, Tortoise 7... Control hole when valve is closed,
18...Valve open control hole 19...'Pinion cylinder. Figure 1 Figure 4 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] 1 Consists of a drive cylinder that has a drive piston that reciprocates in the axial direction in cooperation with a tappet, and an actuation cylinder that has an actuation piston that is actuated by hydraulic pressure generated by the drive piston to drive the valve. In the valve timing changing device, the actuating cylinder has an actuating cylinder chamber that receives pressurized oil from the drive cylinder, and an oil release that communicates with an oil outlet to release excess pressurized oil. a groove, the drive cylinder is provided with an oil supply hole through which pressurized oil is supplied, a valve opening control hole that communicates with the oil supply hole and opens into the oil pressure generation chamber, and between the oil supply hole and the oil pressure generation chamber. An oil passage that extends between the oil pressure generation chamber and the working cylinder chamber and is equipped with a check valve that only allows oil to flow toward the hydraulic pressure generating chamber; The oil passage includes a stop valve, and a valve closing control hole that communicates with the working cylinder chamber and opens into the cylindrical hole of the driving cylinder, and the driving piston faces the hydraulic pressure generating chamber of the driving cylinder and has an axis line. a valve-opening control edge that is inclined relative to the axis; a valve-closing control edge that is inclined with respect to the axis on another land spaced apart from the land of the valve-opening control edge in the axial direction via a notched groove; and the notched groove. and an oil passage communicating with the hydraulic pressure generation chamber, and the direction of inclination of the valve open control edge and the valve close control edge is adjusted relative to the valve open control hole and the valve close control hole, respectively. The diesel engine is characterized in that the opening and closing timings of the valves are related to each other in the same relational direction, and the timing of opening and closing the valves is changed by rotating the driving piston according to the load of the diesel engine. Engine valve timing change device.