JPS6238830A - Scavenging controller - Google Patents

Abstract

PURPOSE:To open and close a scavenge hole formed on a cylinder linear easily and precisely by connecting a scavenging control valve for opening and closing the scavenge hole to an air pressure drive for link motion in order to control supply and exhaust of air pressure against the said drive by reciprocal motion of a piston. CONSTITUTION:In the case of descending stroke of a piston 33, when a lower air through groove 40 passes an air through hole 42 of a lower piston cover 41, a piston bar 39 blocks the air through hole 42, and then compresses air inside an air piston chamber 46 when a scavenge hole 32 starts to be closed by a lower piston ring 45. And, when piston 33 reaches near bottom dead center, an upper air through groove 43 is communicated with the air through hole 42, compressed air inside above chamber 46 flows into an air pressure cylinder 35, a scavenging control valve 4 is lowered by descending motion of a piston 36 against a spring 37, and the scavenge hole 32 is opened. The opening operation lasts until the piston 33 is shifted to the ascending motion and the lower air through groove 40 opens the air through hole 42.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a scavenging air control device for an internal combustion engine.

2. Description of the Related Art For example, in a scavenging engine in which air flows into a cylinder through a scavenging hole and combustion gas in the cylinder is discharged through an exhaust hole or an exhaust valve, exhaust start has conventionally been used as a means to improve the thermal efficiency of the engine. It is widely known to delay the timing to increase the work of expansion within the cylinder. In other words, Fig. 6 shows the acupressure diagram near the bottom dead center of the scavenging type engine, and by delaying the exhaust start timing from the normal case, the shaded area in the figure can be improved. It is explained that the indicated mean effective pressure increases due to the increase.

However, if the exhaust start time is delayed, in the case where the scavenging hole is normally opened and closed at the top of the piston, the gas pressure in the cylinder is still high when the scavenging hole is open, and combustion gas flows back from the cylinder into the scavenging chamber. There is a risk that various problems may occur.

For this reason, in such scavenging engines, various scavenging air control devices have been proposed that open and close the scavenging holes at appropriate times, in addition to opening and closing the scavenging holes by the movement of the piston.

Such scavenging air control devices generally consist of a scavenging air control valve that opens and closes the scavenging air hole portion of the cylinder liner, and a drive device that operates this scavenging air control valve. The performance is such that the scavenging control valve opens instantly when the piston descends as close to bottom dead center (BDC) as possible during the downward stroke of the piston.

Thereafter, the piston shifts to the upper arm stroke, and after the piston itself closes the scavenging hole and completes the scavenging stroke, the scavenging control valve opens, and it is necessary to prepare for the next scavenging. In addition, in this J: Una scavenging air control device, the start of scavenging is at a crank angle that is slower than in conventional engines. It becomes necessary to ensure the opening of the cotton pores and the treetops.

FIGS. 7(a) to (d) and FIG. 8 show examples of conventionally proposed scavenging air control devices.

Figures 7(a) to (d) were proposed in Japanese Patent Application No. 57-26579@, and in these Figures 7(a) to (d), 1 indicates a predetermined scattering in the circumferential direction of the cylinder liner 2. This scavenging hole 1 is provided with a plurality of flat valve seats 3 that are inclined downward in the cylinder axis direction on the outer periphery of the cylinder liner 2 portion. That is, the outer periphery of this portion of the cylinder liner 2 is processed into a polygonal pyramid shape.

Reference numeral 4 denotes a scavenging control valve disposed for each scavenging hole 1, which includes a valve body 5 that contacts the valve seat 3 and covers the scavenging hole 1, and this valve body 5.
The hydraulic cylinder device 8 is fixed to an engine body 7 so that an operating rod 6 having a tip at its tip moves forward and backward in the direction of the cylinder axis of the engine. Each hydraulic cylinder device 8 is
They are connected in parallel via hydraulic piping 9 so that they operate simultaneously. 10 is hydraulic oil, and 11 is a spring for pushing back the piston 12. Further, 13 is a guide for guiding the working rod 6, and is attached to the outer periphery of the cylinder liner 2. 14 is a stopper fixed to the outer periphery of the cylinder liner 2 above the scavenging hole 1.

At 1Ilfc above, when the gas is expanding within the cylinder liner 2, the hydraulic cylinder device 8 is filled with the hydraulic oil 10, as shown in FIG. 7(a).

' As shown in (b) and (d), the scavenging hole 1 is closed by a valve body 5. Now, when the hydraulic oil 10 is discharged from the hydraulic cylinder device @8 at a predetermined opening time, the valve body 5 is lowered and the scavenging hole 1 is opened as shown in FIG. 7(C). When closing the scavenging hole 1 at a predetermined time, hydraulic oil 10 is supplied into the hydraulic cylinder device 8 to raise the valve body 5 and bring it into contact with the valve seat 3.

However, the conventional example shown in FIG. 7 has the following problems.

(b) In order to increase the opening speed of the valve body 5, the spring 1
It is necessary to increase the restoring force of No. 1, but in this case, the pressure of the hydraulic oil required to close the valve must be increased.

(b) The valve opening speed is also restricted by the discharge speed of the hydraulic oil 10.

(c) If the hydraulic oil 10 is supplied by, for example, a motor-driven hydraulic pump, a motor drive power that considerably reduces the benefit of reducing the fuel consumption rate of the internal combustion engine by the scavenging control valve is required.

(d) Furthermore, a control device is required to discharge and supply the hydraulic oil 10 in synchronization with the crank angle.

FIG. 8 shows another conventional example, which was published in Japanese Patent Application Laid-Open No. 55-125.
This is proposed in Publication No. 318. The configuration and operation in FIG. 8 will be explained below. A scavenging control valve 4 is fitted on the outside of the cylinder liner 2 so as to be able to freely slide up and down to open and close the scavenging hole 1, and a hydraulic pump 17 having a plunger t16 reciprocally driven by the lower surface of the piston 15 is provided. A hydraulic piston 18 that reciprocates with pressure oil discharged by the hydraulic pump 17 to drive the air control valve 4.
is provided. The hydraulic pump 17 is connected to an oil supply hole 21 from an external hydraulic pressure supply source 19 via a check valve 20.
is constantly supplied with low pressure oil. In addition, the hydraulic pump 17
A high-pressure pipe 24 between the discharge hole 23 and the hydraulic piston 18 is configured to allow only flow of pressure oil toward the hydraulic piston 18 from the discharge hole 23 of the barrel 22, which is slidably fitted into the plunger 16 of the barrel 22. A check valve 25 is interposed in the oil passage. The barrel 22 of the hydraulic pump 17 is provided with an oil drain hole 26 that is closed by the plunger 16 of the hydraulic pump 17 at the end of the downward stroke of the piston 15.

Therefore, the check valve 2 is discharged from the discharge hole 23 of the barrel 22.
The scavenging control valve 4 is opened by high-pressure oil supplied to the hydraulic piston 18 through the piston 5, and then the piston 15 closes the scavenging hole 1 and is then driven by the lower surface of the piston 15. The plunger 16 of the hydraulic pump 17 returns, and the return hole 27 formed in the barrel 22 is opened. That is, after the upper surface of the piston 15 closes the scavenging hole 1, the pressure oil to the hydraulic piston 18 is discharged into the barrel 22 from the return hole 27 via the check valve 28, and then the scavenging control valve 4 is closed. The scavenging hole 1 is closed.

Therefore, even if the start of opening of the exhaust valve is delayed, the start of opening of the scavenging hole can be delayed by taking a sufficient period of high-pressure exhaust necessary for the cylinder pressure to fall below the scavenging pressure.

Problems to be Solved by the Invention However, the conventional example shown in FIG. 8 has the following problems.

(a) Since the pressure oil is forcibly discharged by the reciprocating motion of the piston 15, in the event that the scavenging control valve drive device etc. becomes stuck, the hydraulic pressure in the drive hydraulic line will be reduced because the drive oil is incompressible. This led to accidents such as damage to the hydraulic pipe system due to the folding screen.

fb) In the event of the accident described in (a) above or when the piping becomes loose, the driving oil will scatter into the scavenging chamber, causing serious damage such as a fire in the scavenging chamber.

(C) This hydraulic drive system requires an external hydraulic power supply source 19 with a considerable discharge capacity. That is, piston 1
During the period when the piston 15 is above the scavenging hole 1, which occupies most of the reciprocating stroke of 5, the lower surface of the plunger 16 is in the position shown in FIG. The low pressure oil supplied to 21 is directly drained from the oil drain hole 26 to the sump tank. Further, it is necessary to supply an amount of oil corresponding to the stroke (L) of the plunger 16 each time the piston 15 reciprocates. Therefore, a driving power for the external hydraulic power source 19 is required to the extent that the benefit of reducing the fuel consumption rate of the internal combustion engine by the scavenging control valve 4 is considerably reduced.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, to open and close the scavenging holes accurately at desired times, and to significantly improve the thermal efficiency of the engine.

Means for Solving the Problems In order to solve the above problems, the present invention provides a scavenging air control valve that can open and close the scavenging air hole in the scavenging air hole portion of the cylinder liner of an internal combustion engine. A pneumatic drive device is interlocked to energize the scavenging air control valve to close and operate the scavenging air air control valve when pressurized air is supplied, and is externally fitted and slidably connected to the piston rod at the bottom of the cylinder liner. A lower piston cover is provided, and the piston, the cylinder liner, the lower piston cover, and the piston rod define an air piston chamber capable of compressing air during the downward stroke of the piston, and the lower piston cover has one end attached to the piston. A first air passage is formed in the inner circumferential surface of the lower piston cover, and the other end thereof communicates with the pneumatic drive device, and the piston rod is provided with a first air passage that opens into the air piston chamber when the piston approaches the bottom dead center. and a second air passage that communicates with the first air passage to supply pressurized air to the pneumatic drive device, and a second air passage that communicates with the first air passage after the scavenging hole is closed by the piston and A third air passage is formed to exhaust the air inside the pneumatically driven equipment.

In this way, when the piston is halfway through its downward stroke, the lower piston ring of the piston begins to close the scavenging hole, and the third air passage passes through the first air passage, the piston rod Due to the internal sliding contact with the lower piston cover, the air piston chamber is closed and the air within the air piston is compressed. When the piston approaches bottom dead center, the second air passage communicates the air piston chamber with the first air passage, so that the pressurized air in the air piston chamber is supplied to the pneumatic drive device. , the scavenging control valve is opened. When the piston moves to the upward stroke, communication between the air piston and the first air passage through the second air passage is cut off, but at this point, the frontage of the first air passage on the inner peripheral surface side of the lower piston cover is cut off. is closed by the piston rod, so the scavenging control valve (maintained in the open state).

After that, when the piston rises further and blocks the scavenging hole,
Next, the third air passage and the first air passage are brought into communication, and as a result, the pressurized air within the pneumatic drive device is discharged, thereby closing the scavenging control valve.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

31 is a cylinder liner equipped with a scavenging hole 32. A piston 33 is fitted into the cylinder liner 31 so as to be able to freely slide up and down, and is opened and closed by a v1 air cam (not shown) at the top of the cylinder liner 31. An exhaust valve (not shown) is provided. The lower end of the scavenging hole 32 is formed to coincide with the upper surface of the piston 33 at bottom dead center (BDC). Furthermore, a scavenging control valve 34 is provided outside the cylinder liner 31.
The air control valve 34 is connected to a pneumatic piston 36 of a pneumatic cylinder 35 as a pneumatic drive device, and when no air pressure is applied, the restoring force of a spring 37 causes an upper stopper to be inserted. 38, and the scavenging hole 32 is closed when the scavenging control valve 34 rises.

The lower part of the piston rod 39 is equipped with a lower air passage groove 40 as a third air passage, and the lower part of the cylinder liner 31 is provided with a lower piston cover 41 whose sliding surface is the outer surface of the piston rod 39 portion. has been done. Further, the lower piston cover 41 is provided with an air passage hole 42 as a first air passage whose air inlet and outlet are on the side in contact with the piston rod 39.
An upper air passage groove 43 is provided as a second air passage, and the air passage hole 42 of the lower piston cover 41 is connected to the pneumatic cylinder 35 through a high pressure pipe 44.

In such a configuration, the lower air passage groove 40 and the upper air passage groove 43 have a sufficient distance, so that in the downward stroke of the piston 33, the lower air passage groove 40 first passes through the lower piston cover 41. Once the air passes through the air passage hole 42, the piston rod 39 closes the air passage hole 42, and when the piston 33 further descends and the lower piston ring 45 begins to close the scavenging hole 32, that is, the crank angle reaches the point shown in FIG. (θ5), the air in the air piston chamber 46 is compressed. Near the end of the downward stroke of the screws 1 to 33, that is, near the bottom dead center (BDC), the lower air passage groove 43 closes to the air passage hole 42.
Therefore, when the crank angle is θ6) in FIG. It resists and is pushed down.

As a result, the crank angle is at (θ2) in Fig. 4,
The scavenging control valve 4 is rapidly pushed down, and the scavenging hole 32
Let's open.

Further, the piston 33 passes through the bottom dead center (BDC) and starts the upward stroke, and when the crank angle reaches (θ7) in FIG. 4, the communication between the upper air passage groove 43 and the air passage hole 42 is cut off, and the piston rod Since the air passage hole 42 is closed at the outer periphery of the cylinder 39, the compressed air within the pneumatic cylinder 35 is sealed. With this connection, the scavenging control valve 34 is maintained in the open position.

The piston 33 further rises, the upper surface of the piston 33 reaches the upper end of the scavenging hole 32, and the crank angle changes to (θ4) in FIG.
The scavenging stroke is completed at . Next, the lower air passage groove 40
In order to open the air passage hole 42 of the lower piston cover 41 when it reaches the crank angle (θ8) shown in FIG. 4,
The compressed air contained within the pneumatic cylinder 35 is discharged into the scavenging chamber. Due to this binding and the restoring force of the spring 37, the pneumatic piston 36 and the scavenging control valve 34 rise, and the scavenging hole 34 moves upward at the crank angle (θ9) shown in FIG.
is closed and ready for the next scavenge.

In this way, in the embodiment of the present invention shown in FIGS. 1 and 2, the scavenging holes 32 begin to open at a slower crank angle (θ2) than in the conventional engine, as shown in FIGS. 3 and 4. However, by making the scavenging air hole height H2) higher than the conventional engine's underhole height Hl), the bottom dead center (BD
In C), the scavenging hole opening area when fully opened increases, and the crank angle (θ4) at which the scavenging hole 32 closes due to the rise of the piston 33 also approaches, making it possible to obtain the same scavenging hole opening time area as in the conventional engine. can. The crank angle at which the scavenging hole begins to open can be delayed while maintaining the scavenging hole opening time area to the same degree as that of conventional engines, which lengthens the effective stroke of the piston 33 and greatly improves fuel consumption. . Furthermore, the present invention has a number of advantages over those previously proposed, including:

(a) The power source for driving the scavenging control valve is obtained from the rotation of the engine itself. For this reason, compared to a hydraulic drive system that requires external consumption such as a motor-driven hydraulic pump to supply the amount of oil used each time the scavenging control valve opens and closes, this requires less mechanical effort on the engine side. The power loss is a sufficiently small value.

(b) In the case of hydraulic drive, if an accident occurs, the driving oil will scatter in the scavenging chamber, causing serious injury and damage such as a fire in the scavenging chamber, but with pneumatic drive, there is a possibility of such an accident. There are none.

(C) In the conventional hydraulic drive system as shown in Figure 8, if the scavenging control valve drive device etc. were to become stuck, the drive oil is incompressible, so the oil pressure in the drive hydraulic line would be abnormally increased. This could lead to an accident such as damage to the pipe system, but since the present invention is driven by compressible air pressure, even in such a case, the air pressure in the drive air system would only increase a little, which could lead to damage.
! [There are very few.

(d) When driving a scavenging control valve with a fluid pressure cylinder, usually multiple fluid pressure cylinders are required.
In this case, if we use an incompressible liquid such as hydraulic pressure,
A slight difference in piping volume or piping resistance to each fluid cylinder causes an imbalance in the transmission of hydraulic pressure to each fluid pressure cylinder, and this imbalance becomes larger as the opening/closing speed of the scavenging control valve increases. This makes it difficult to open and close at high speed. However, since the air pressure of the present invention is compressed and expandable, the degree of imbalance in pressure transmission to each fluid pressure cylinder is smaller than that of hydraulic pressure, and therefore the opening and closing operation of the scavenging air control valve is not hydraulic. It is smoother in comparison.

(e) Compared to the conventional hydraulic drive system shown in Figure 8, a check valve is not required and piping is simpler.

(f) The driving air source mechanism can be obtained without changing the main structures such as the cylinder liner and the scavenging air chamber, making it easy to equip the current engine.

(g) According to the present invention, even if compressed air from the air piston chamber 46 starts to be supplied to the pneumatic cylinder 35 at the crank angle (θ6), the air piston chamber 46 does not reach the bottom dead center (BDC>). Since the air pressure in the air chamber is still in the compression stroke, high pressure air can be continuously supplied to the pneumatic cylinder 35.Moreover, the compression speed of the compression pressure in the air chamber piston 46 is proportional to the rotational speed of the internal combustion engine. Therefore, the opening speed of the scavenging pipe side valve becomes correspondingly high.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the spirit of the present invention. In particular, in this embodiment, for convenience of explanation, the scavenging air control valve and the pneumatic cylinder for driving the scavenging air control valve are of the up-and-down reciprocating type; however, this is not limited to the up-and-down reciprocating movement, and these parts are The present invention can be applied to any combination of a scavenging control valve that opens and closes a scavenging control valve and a device that uses air pressure as a scavenging control valve driving device.

In the embodiment shown in FIG. 1, the pneumatic cylinder 35
Although a spring 37 is used as the restoring member, the following advantages can be obtained by adopting a pneumatic spring mechanism as shown in FIG. 5 instead.

(a) At the uppermost position of the pneumatic piston 36, that is, at the closed position of the scavenging control valve 34, the value corresponding to the initial load by the spring 37 in FIG.

(b) At the lowest position of the pneumatic piston 36, that is, at the closed position of the scavenging control valve 34, a value corresponding to the restoring force due to the compression of the spring 37 in FIG. 1 can be determined by the eight suspensions of the air tank 49. .

(c) By appropriately setting the values of (a) and (b) above, the driving force required to open the scavenging control valve 34 can be reduced, and a valve opening speed faster than Jζ can be obtained. can.

(d) The volume of the lower air spring chamber 47 at the lowest position of the pneumatic piston 36 may be small, and the outer diameter, length, etc. can be significantly reduced compared to the pneumatic cylinder adopting the restoring spring 37 shown in FIG. Can be shortened. In addition, 48 is a pipe line, 50 is a check valve, and 52 is an air pressure supply source.

Effects of the Invention As described above, according to the present invention, the power source for driving the scavenging control valve is obtained from the rotation of the engine itself, so that the mechanical power loss on the engine side can be reduced. Furthermore, since air pressure is used, accidents such as fire and damage to pipes can be prevented, and the scavenging holes can be opened and closed appropriately at desired times.

[Brief explanation of the drawing]

Figure 1 is a sectional view of an embodiment of the present invention, Figure 2 (aHb)
1 is a sectional view taken along line A-A and B-8 in FIG. 1, FIGS. 3 and 4 are explanatory views of the operation of the apparatus shown in FIGS. Figure 6 is a diagram illustrating a finger pressure diagram near the bottom dead center of a scavenging type engine.
FIGS. 7(a) to 7(d) are diagrams showing a first conventional example, and FIG. 8 is a diagram showing a second conventional example. 31... Cylinder liner, 32... Scavenging hole, 33...
... Piston passage groove (third air passage), 41... Lower piston cover, 42... Air passage hole (first air passage), 43... Upper air passage groove (second air passage) ), 4
6... Air piston room agent Yoshihiro Morimoto Figure 5 Figure DC (Bottom death) (Tonneau)

Claims (1)

[Claims] 1. A scavenging control valve that can open and close the scavenging hole is provided in the scavenging hole portion of the cylinder liner of the internal combustion engine, and the scavenging control valve is energized to close, A pneumatic drive device that opens the scavenging control valve when pressurized air is supplied is interlocked and connected, and a lower piston cover is provided at the bottom of the cylinder liner to fit externally into sliding contact with the piston rod. The liner, the lower piston cover, and the piston rod constitute an air piston chamber capable of compressing air during the downward stroke of the piston, and one end is opened to the inner circumferential surface of the lower piston cover, and , the other end forming a first air passage communicating with the pneumatic drive device, and causing the piston rod to communicate the air piston chamber with the first air passage when the piston approaches bottom dead center. a second air passage for supplying pressurized air to the pneumatically driven equipment; and a third air passage that communicates with the first air passage to exhaust air in the pneumatically driven equipment after the scavenging hole is closed by the piston. A scavenging air control device characterized by forming an air passage with a