JPH01244111A - Method of controlling closing motion of exhaust valve and exhaust valve used for said method - Google Patents

Abstract

PURPOSE: To freely change effective compression ratio by changing the oil exhaust quantity from working chamber of an exhaust valve corresponding to the load condition of the engine. CONSTITUTION: A working plunger 10 of exhaust valve is arranged in a cylinder 4 defining a working chamber. A first diaphragm rim 25 and a second diaphragm rim 26 are arranged in the cylinder 4, a working chamber 27 between the two diaphragms 25, 26 is connected through duct 28 including a regulative throttle valve 29 to oil outlet 23. The throttle valve is regulated corresponding to the load conditions of the engine. Therefore, all the open time of the exhaust valve can be controlled and the effective compression ratio can freely be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention provides that the exhaust valve includes an actuating plunger housed in an oil cylinder, the actuating plunger cooperating with the exhaust valve when supplied with pressurized oil. to apply an opening movement to this exhaust valve and the closing of a hydraulically actuated exhaust valve in internal combustion engines of the type, in particular two-stroke uniflow scavenged marine diesel engines, in which the actuating plunger defines a working chamber of hydraulic oil. It is related to motion control methods.

The invention also relates to an exhaust valve used in the above method.

[Prior Art and Problems] As is known, the total efficiency of a diesel engine is defined as the product of the mechanical efficiency and thermal efficiency of the engine. The mechanical efficiency depends on the mechanical conditions of the engine. In other words,
In order to operate various auxiliary devices such as pumps and generators, and to operate valves by camshafts, etc., and internal parts such as in bearings and between pistons and cylinders 11! ! It depends on the consumption rate of the engine efficiency to overcome the stamping. Thermal efficiency is an expression of how completely the combustion process in actual use progresses, and in this sense it is particularly dependent on the pressure and temperature conditions under which this combustion process occurs.

The improvement in one or both of the aforementioned efficiencies therefore results in an improvement in the overall efficiency of the engine and thus a lower fuel ratio.

As mentioned above, the combustion process is dependent on the actual pressure and temperature conditions in the engine. These conditions are closely related to each engine's compression ratio and the timing and length of fuel injection time. Since increases in pressure and temperature must necessarily correspond to corresponding structural provisions, in practice it is the engine that determines the equilibrium point of the above-mentioned somewhat contradictory requirements, for example in order to obtain the maximum permissible combustion pressure. Economic reasons are related to production cost and weight.

For each engine, it is desirable to maintain a given maximum combustion pressure within certain limits by timing the moment of fuel injection, since the compression ratio of the engine is fixed and the engine has a particularly low pressure from compression to combustion pressure. Since the design is designed for optimum running in a load range of almost 100% with respect to pressure jumps, considerable pressure jumps occur at partial and low loads. Such high pressure jumps are undesirable because they increase the risk of abnormally high cylinder wear, piston ring collapse, blow pie, and piston ring failure.

In the recent Uniflow 2 stroke 1 engine,
The exhaust valve closes after the scavenging boat. It is therefore possible in principle to vary the effective compression ratio of an operating engine by controlling the closure of the exhaust valve.

In the method according to the invention, the flow of pressure oil discharged from the working chamber of the exhaust valve is determined in one or more mechanically determined stationary throttling stages between the working plunger and the cylinder, depending on the load conditions of the engine. by and/or! ! It can be varied by a freely adjustable diaphragm member made of Ill.

By controlling the closing movement of the exhaust valve in this way, and thus the total opening time of the exhaust valve, it is now possible to freely change or vary the effective compression ratio during operation of the engine. This makes it possible, on the one hand, to keep the compression jump at a given load condition at an optimal level with respect to cylinder efficiency and conditions, and, on the other hand, to increase the effective compression ratio at low or part load conditions so that this This is highly desirable as it improves the operating conditions under normal conditions.

In fact, the above-mentioned advantages of the above-mentioned hydraulic control.

This is achieved by linking it to an appropriate length R11 of the cam surface contour on the camshaft of the oil pump.

Since it is undesirable to close the exhaust valve sooner than the downstream contour of the cam face of the camshaft corresponds to, the cam is designed like a traditional cam, i.e. the "shortest" part of its profile is connected to the engine. is designed to accommodate the desired maximum compression ratio. As mentioned above, by controlling the closing movement of the exhaust valve so that it no longer follows the contour of the camshaft,
Valve closure is postponed, thus reducing the effective compression ratio.

This is used to keep the compression pressure constant in the upper load area of the engine and, since the compression pressure is constant in this load area, also to keep the pressure jazz constant.

This is because in a normal engine with a fixed compression ratio, the effective compression ratio (MCR: continuous maximum output) of the engine at 100% load must remain unchanged.

The engine clearance volume, ie the volume above the piston at TDC (Top Dead Center), is reduced. As a result, the engine's expansion ratio is increased at a given load, and fuel consumption is improved since the exhaust valve opening time remains unchanged.

The first exhaust valve used to carry out the method of the invention
The difference between this embodiment and conventional exhaust valves is that the part of the cylinder defining the working chamber includes two axially spaced restricting edges, and the side surfaces of the working plunger defining said working chamber are axially spaced apart. It has the shape of a stud extending in the direction,
This stud has longitudinally different diameters and preferably has three axially spaced apart throttle parts cooperating with the throttle edge of the cylinder, the actuating plunger being in a position corresponding to full opening of the exhaust valve. The vi1 throttle part located furthest away from the actuating plunger interacts with the first throttle edge of the cylinder when the actuating plunger assumes a position corresponding to the closing of the exhaust valve; The throttle edge of the cylinder and the throttle portion of the actuating plunger are mutually disposed such that the throttle portion is in contact with the second throttle edge of the cylinder, and the throttle edge of the cylinder is defined and actuated between the first throttle portion and the first throttle edge. The working chamber portion remote from the plunger is directly connected to the oil outlet and is also connected to the first oil outlet of the cylinder.
The difference is that the working chamber section between the throttle edge and the second throttle edge is connected to the oil outlet through a duct containing an adjustable throttle valve.

In the exhaust valve of the s2 embodiment of the invention, the actuating plunger is provided with an axial bore as part of the working chamber on the side defining the working chamber.

The cylinder includes a cylindrical stud that sealingly engages the bore during a predetermined portion of movement of the actuation plunger.

The stud has a throttle duct including an adjustable throttle valve, the throttle duct opening communicating with the end face of the stud opposite the actuating plunger at one position of the throttle valve, and the throttle duct having an adjustable throttle valve. In the other position, the opening in the cylindrical surface of the stud communicates with an opening in the cylindrical surface of the stud at a predetermined axial distance from the end face of the stud, such that the opening in the cylindrical surface of the stud is in communication with the opening in the cylindrical surface of the stud at a predetermined axial distance from the end face of the stud, such that the opening in the cylindrical surface of the stud is in communication with the opening in the cylindrical surface of the stud at a predetermined axial distance from the end surface of the stud, so that the opening in the cylindrical surface of the stud is in communication with The axial distance of said opening corresponds to the stroke of the actuating plunger, as closed by the plunger.

[Embodiments] Hereinafter, embodiments of the present invention shown in the drawings will be described in detail.

The hydraulically operated exhaust valve 1 shown in FIG.
The housing has a bottom part 3 and an oil cylinder 4. This exhaust valve, together with its bottom part 3, is installed inside the cylinder cover at the upper end of the cylinder of a uniflow two-stroke marine diesel engine. In the center of the exhaust valve, an axially movable valve body 5 in the form of a disc valve is pivoted in a conventional manner. This valve body 5 is pressed upward by an air spring 6 disposed in the oil cylinder 4, so that in the closed state of the valve, the disc valve and the bottom part 3
The respective opposed annular sealing surfaces of the cylinders engage with each other and isolate the interior of the cylinder from the exhaust duct 7.

The upper part of the valve body 5 cooperates with an actuating plunger 10 housed in the bore 8 of the oil cylinder 4, and the side of the plunger opposite from the valve body 5 is connected via a duct 11 to a conventional camshaft drive. It communicates with a hydraulic system 12 in the form of a pump.

As shown more clearly in FIG. 112, the actuating plunger 10 comprises an axial stud 15 extending in the opposite direction from the valve body 5. This stud has a partially hollow actuating plunger 10 which surrounds the upper part of the valve body 5 and includes three separate sections, a first constriction section 16, an intermediate section 17 and a second constriction section 18. It is in sealing engagement with the hole 8.

An insert 20 is attached to the upper end of the oil cylinder 4 and extends partially into the hole 8 below.

This insert forms an internal hollow space 21, which space accommodates the insert 20 and the oil cylinder 4, respectively.
It is connected to the hydraulic system 12 of FIG. 1 through two holes 22, 23 provided in it. The insert 20 has, on its end face facing the plunger 10, two radially inwardly projecting diaphragms, No. 1 #25! 2a26 is provided. The relatively small space 27 defined by these edges is 11! It is connected to the hollow space 21 through a duct 28 containing an adjustable throttle valve 29. A check valve 32 for blocking the flow to the hollow space 21 is placed f1a in the duct 31, and this duct 31 reaches the end face of the insert 20 facing the valve body 5, and connects the hollow space 21 to the plunger 10 and the insert 20. Connect to the space 35 between.

The mode of operation of the exhaust valve shown in FIG. 2 will be explained in detail with reference to FIG.

A camshaft pump 12 is controlled by the exhaust profile on the camshaft and pumps pressure oil through the duct 11 to the oil cylinder 4.
, the oil pressure in the space 21 increases. Therefore, the valve body 5 of the plunger 10
As a result of the hydraulic pressure against the axially opposite end face from
The plunger 10 is pushed toward the valve body 5 in the axial direction. Hydraulic pressure is applied to the upper end surface 36 of the stud 15 and the stud 15
In the valve closed state shown, the second throttle part 18 and the second throttle edge 2
6, the pressure oil acts only slightly on the annular Sikorda part 38 of the plunger 10; instead, a strong pressure increase causes the check valve 32 to open and
The pressure oil passing through the duct 31 thus comes into contact with said shoulder 38 of the plunger. After a short downward movement of the actuating plunger 10 corresponding to a certain opening of the exhaust valve 5, j
The I2 throttle part 18 and the second throttle edge 26 are spaced apart from each other, so that the pressure oil mainly flows along the intermediate part 17 to the throttle a
25 and 26 and reaches shoulder 38. However, there is still a travel throttling effect, so that a constant amount of pressure oil continues to flow through the check valve 32 and the duct 31. This is especially true at the end of the stud movement.
6 engages with the first aperture edge 25.

During this cycle, the valve body 5 moves in accordance with the contour of the exhaust cam, for example according to the ascending graph 40 in FIG.

When the valve is fully open at time t2, the first constriction part 16 of the stud 5 of the plunger 10 is in the insert 2
0, the valve is open by a distance hz-h□.

When the valve begins to close at time t3, the throttle valve 29
Depending on the adjustment of , it follows a solid line graph 40 corresponding to the downstream side of the cam profile, or a falling graph, such as graph 40a or 40b, which is substantially parallel to this graph.

If the valve 29 is completely open corresponding to the minimum restriction, the pressure oil forced out of the space 35 will flow freely along the duct 28 as a result of the upward action of the air spring 6 on the valve body 5 and the valve 29 The pressure oil is introduced into the oil cylinder 4.
It is discharged from the discharge port 23. There is no noticeable throttling effect and the valve body 5 closes according to the graph 40 as described above. Since the rollers of the camshaft 12 follow the downstream side of the cam profile, adequate energy recovery is obtained. Just before complete closure of the valve, the second throttle portion 18 engages the second throttle mark 26. This buffers the effects of street attacks to some extent. This is because the pressure oil remaining in the space 35 can only reach the outlet 23 after passing through the narrow slit between the throttle bands. This reduces the valve's striking speed. This impact effect is independent of the throttle valve 29 and therefore always occurs regardless of its adjustment. This is illustrated by the short graph sections 41a, 41b, 41c in the If3 diagram.

If the throttle valve 29 is completely closed in response to the maximum throttle,
The pressure oil present in chambers 28 and 35 flows through the first constriction section 16.
and the first aperture edge 25 only through the slit between the outlet 2
You can reach 3. This squeezing effect is.

This prevents the valve from closing in response to the downstream side of the cam profile, and since the valve "releases" the cam, it closes synchronously only with the backflow of pressure oil through said slit.

Such a delay in the closing action of the valve corresponds to the period ts-t in FIG. When the first throttle bands are spaced apart from each other, the valve rwls along graph 40b of FIG.
ML. As mentioned above, the closing speed is determined by the gap between the intermediate part 17 of the stud and the two throttles 1a25,28. Also, as mentioned above, the impact action is eventually relieved.

By adjusting the throttle valve 29 in this manner, the closing delay of the exhaust valve can be lengthened or shortened.

Therefore, as stated in the introduction, the compression ratio of the engine can be effectively controlled.

The throttle valves are adjusted in response to the actual load conditions of the engine; such adjustment can be carried out, for example, by connecting the adjusting lever of each throttle valve to a common connecting rod and adjusting the charge air, which is detected by a conventional pressure sensor. This is carried out by electrically or pneumatically displacing the connecting iron in response to the pressure in the receiver.

FIG. 4 shows a second embodiment of the exhaust valve of the present invention.

The actuating plunger 50 is formed with a central cavity 51;
At its orifice opposite the valve body 5, a radially inwardly directed annular collar 52 is provided. The insert 55 has a central stud 56 projecting toward the actuation plunger 50.
This stud has a central hole 57, and this hole 57
An adjustable throttle valve 58 is housed within. Downstream of the valve seat 59, the bore 57 communicates by means of a transverse duct 60 with a chamber 62, which is arranged around the stud and connects directly with the pressure oil inlet-outlet 63 of the oil cylinder 4. .

In this case, when pressure oil is supplied from the inlet 63, the actuating plunger 50 and therefore the valve body 5 are moved to the valve closed position shown in FIG. will be moved from In this structure, the pressure oil directly acts on most of the operating area of the actuating plunger, so pressure is applied to the area of the actuating plunger that is not directly affected by the rising hydraulic pressure at the beginning of the valve opening movement as in the above structure. It does not require a check valve controlled pressure oil duct for the inflow of oil, but depending on the actual pressure conditions the cavity 5
In order to prevent cavitation phenomena in the chamber 62, it is preferable to insert a duct that reaches the lower end of the stud 56 and connects it to the chamber 62.

As before, the opening of the valve occurs substantially along the upstream side of the cam profile. After a certain degree of opening, this opening stroke is illustrated by graph 70 in FIG. 5, cavity 51 of actuating plunger 50 separates from stud 56.

When the oil pressure decreases and the valve begins to close, the actuating plunger 50 initially rises towards the stud 56 at a speed corresponding to the situation in which the oil pump rollers follow the downstream side of the cam profile. Once the stud 56 engages the cavity 51, the subsequent closing movement of the valve depends on the adjustment of the throttle valve. This is because the oil remaining in the cavity 51 can only escape from said cavity through the duct 57 with the throttle valve 58 or through the narrow gap between the annular collar 52 and the outer surface of the stud 56. If the throttle valve 58 is completely closed, the entire amount of oil must pass through the gap, resulting in a maximum closing delay of the exhaust valve. This cycle is illustrated in FIG. 5 by graphical portion 70c. If the throttle valve is partially open, it will close according to graph 70b, but if the throttle valve is fully open, it will follow the solid line graph 70, but w
In the case of Fig. 5, regardless of the adjustment of the aperture force,
Just before the end of the flea season, a certain amount of city fire is obtained.

The annular pot 52 is connected to a transverse duct 6 leading to a channel (62).
The mini-actuating plunger 50 is moved along the stud 56 to cover the outlet of the 0; the buffering effect described above occurs.

This is because the oil remaining in the i-cavity 51 at this time must be expelled through the slit between the annular collar 52 and the outer surface of the stud 56. stud 56
By varying the length of the valve, it is possible to determine the point at which throttling begins when the valve closes.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the hydraulically operated exhaust valve according to the present invention and the corresponding operating system, Fig. 2 is a sectional view of the upper part of the exhaust valve of Fig. 1, and Fig. 3 is the opening characteristic of the exhaust valve of Fig. 2. Graph showing, 4th r
IA is a sectional view of a second embodiment of the exhaust valve of the present invention, and FIG. 5 is a sectional view showing the opening characteristics of the exhaust valve of FIG. 4. 100. Exhaust valve, 4. ,, cylinder, 5. , ,
, valve body, io, , actuation plunge Asahi 15. ,,Stud, 16°17.1B,,,Aperture part, 22,23.
,,Pressure oil inlet-outlet. 25.28. ,,diaphragm edge,21.27. ,,Action Channo<, 28,31゜6. duct, 29. ,,throttle valve,so,,,operating plunger,51.82. , - working chamber, 56. ,,Stud, 57. ,,,
Throttle duct, SS:, Throttle valve, 60...Duct...
Shigeto Sato -Yu F/(3,2 F/(33 F/64

Claims (1)

[Claims] 1. The exhaust valve includes an actuating plunger (10) housed in an oil cylinder, and this actuating plunger cooperates with the exhaust valve (5) when supplied with pressure oil to discharge the exhaust gas. Hydraulically actuated exhaust valve (1) in an internal combustion engine, in particular a two-stroke uniflow scavenged marine diesel engine, of the type which exerts an opening movement on the valve and in which said actuating plunger (10) defines a working chamber of hydraulic oil. In the closed motion control method, the pressure oil discharge flow rate from the working chamber of the exhaust valve is adjusted between the working plunger (10) and the cylinder (4) in response to engine load conditions.
) and/or by means of an adjustable throttle member. 2. It includes an actuating plunger (10) housed in the oil cylinder (4), which actuating plunger cooperates with the exhaust valve (5) to perform an opening movement with respect to this exhaust valve when supplied with pressure oil. An exhaust valve for use in the method according to claim 1, of the type in which the actuating plunger (10) defines a working chamber (21, 27, 35) of hydraulic oil, and a cylinder defining the working chamber. (4) comprises two axially spaced constriction edges (25, 26), and the side surface of the actuating plunger (10) defining said working chamber is provided with an axially extending stud (15). having a shape, the stud has longitudinally different diameters and preferably includes three axially spaced constriction portions (16) cooperating with the constriction edges (25, 26) of the cylinder (4). , 17
.
25), the second throttle part (18) in the position closest to the actuating plunger (10) when the actuating plunger (10) assumes a position corresponding to the closing of the exhaust valve
said cylinder (4) in cooperation with the aperture edge (26);
and the throttle portion (16, 17, 18) of the actuating plunger (10) are mutually arranged, and between said first throttle portion (16) and the first throttle edge (25) a working chamber portion (21) defined and spaced from the working plunger (10) is connected directly to an oil outlet (23);
The working chamber part (27) between the first throttle edge (25) and the second throttle edge (26) of the cylinder also has an adjustable throttle valve (
The oil outlet (23) is routed through the duct (28) containing the oil outlet (29).
2. Exhaust valve for use in the method according to claim 1, characterized in that the exhaust valve is connected to: 3. The actuating plunger housed in the oil cylinder (
50), the actuating plunger (50) cooperating with the exhaust valve (5) to exert an opening movement on the exhaust valve when supplied with pressure oil, and said actuating plunger (50) exerting an opening movement on the exhaust valve (5) when supplied with pressure oil. An exhaust valve for use in the method of claim 1 of the type defining an actuating plunger (50, 62).
) is provided with an axial bore (51) as part of the working chamber in a side defining the working chamber, and the cylinder (4) is in sealing engagement with the bore (51) during a predetermined part of the movement of the working plunger (50). a mating cylindrical stud (56), said stud (56) having a throttle duct (57) containing an adjustable throttle valve (58);
) communicates with the end face of the stud opposite the actuating plunger in one position of the throttle valve (58), and the throttle duct (57) is arranged at a predetermined distance from the end face of the stud in the other position of the throttle valve (58). an opening (60) in the cylindrical surface of the stud (56) at an axial distance of The axial distance of the opening (60) is such that the opening (60) is closed by the actuation plunger (50).
An exhaust valve characterized by being compatible with the stroke of 0). 4. The axial distance between the opening (60) of the throttle duct (57) on the cylindrical surface of the stud and the end face of the stud is such that this opening (60) is not blocked during the stroke of the actuating plunger (50). Exhaust valve according to claim 3, characterized in that it corresponds to the stroke of the actuating plunger (50). 5. The actuating plunger (50) has its axial hole (51)
The stud (5
6) The exhaust valve according to claim 3 or 4, wherein the exhaust valve engages with the exhaust valve.