JP7811563B2 - Exhaust valve drive unit - Google Patents

Description

The present invention relates to an exhaust valve drive device, and more specifically to an exhaust valve drive device used in internal combustion engines such as diesel engines, which reduces drive power consumption.

In internal combustion engines such as diesel engines, an exhaust valve drive device is used to exhaust the fuel from the exhaust port of the combustion chamber after it is burned (exploded) in the combustion chamber, as described in Patent Document 1.

As shown in Figure 14, a conventional exhaust valve drive device is installed over the exhaust port of a combustion chamber (not shown) and includes a housing 100 with an exhaust tube 101 that guides exhaust from the exhaust port. The end of the exhaust tube 101, called exhaust tube end 101a, is butted against the exhaust port of the combustion chamber. Exhaust gas is exhausted from the combustion chamber through the exhaust port of the combustion chamber and exhaust tube end 101a, as shown by arrow e in Figure 14.

This exhaust valve drive device includes an exhaust valve rod 103 supported by a housing 100 so that it can move toward and away from the exhaust tube end 101a. The exhaust valve rod 103 has a valve body 102 at its tip that opens and closes the exhaust tube end 101a, and is hydraulically driven.

The valve element 102 is disk-shaped and closes the exhaust stack end 101a by being pressed against the valve seat 101b (the periphery of the circular exhaust stack end 101a) from the combustion chamber side. The valve element 102 opens the exhaust stack end 101a when the valve seat 101b moves away from the combustion chamber side.

The exhaust valve stem 103 has its tip, the valve disc 102, positioned within the combustion chamber, and its rod-shaped shaft 103a, continuing from the valve disc 102, extending through the exhaust stack 101 and out of the combustion chamber, supported by the housing 100. The valve disc 102 is pressed against the valve seat 101b, as shown by arrow c in FIG. 14, by the gas pressure inside the combustion chamber, as shown by arrow gp in FIG. 14. The shaft 103a of the exhaust valve stem 103 is driven toward the combustion chamber (opening direction, as shown by arrow o) by the hydraulic pressure of the high-pressure driving oil, as shown by arrow op in FIG. 14. An actuator 104 is attached to the base end of the exhaust valve stem 103, which receives the hydraulic pressure op of the high-pressure driving oil and moves the exhaust valve stem 103 in the opening direction.

An air spring 105 is provided on the exhaust valve stem 103. The air spring 105 is configured to compress and expand the volume of the sealed space within an air spring cylinder 106 provided around the exhaust valve stem 103 using an annular piston 107 attached to the exhaust valve stem 103. Air is supplied into the air spring cylinder 106 as shown by arrow p1 in Figure 14, increasing the air pressure.

In this exhaust valve drive device, high-pressure drive oil is pumped into and discharged from a drive hydraulic pump (not shown), and this high-pressure drive oil is sent through a high-pressure pipe to drive the actuator 104. Driven by the high-pressure drive oil, the actuator 104 operates together with the exhaust valve stem 103 to open the exhaust stack end 101a. The drive hydraulic pump has a proportional control valve, and this proportional control valve is configured to open or close the exhaust stack end 101a in response to an exhaust valve open signal or exhaust valve close signal sent from an engine control device (not shown).

FIG. 15A is a graph showing the force acting on the exhaust valve rod 103 (exhaust valve acting force pattern) and the opening degree of the exhaust tube end 101a (valve body 102) in this exhaust valve drive device.
FIG. 15(b) is a graph showing the pressure change of the high-pressure oil for driving and the opening degree of the exhaust tube end 101a (valve element 102) in this exhaust valve driving device.
In Figure 15 (a), the opening direction of the exhaust pipe end 101a is shown as positive (+) and the closing direction is shown as negative (-), and the opening degree of the exhaust pipe end 101a (valve body 102) (dashed line), the inertial force of the exhaust valve rod 103 (dotted line), the gas pressure gp in the combustion chamber acting on the valve body 102 (dotted line), and the force of the air spring 105 (thin line) are shown.
In FIG. 15(b), the opening direction of the exhaust stack end 101a is indicated by a positive (+) sign and the closing direction is indicated by a negative (-) sign, and the pressure of the high-pressure oil for driving is shown (thin line).

In this exhaust valve drive device, the exhaust tube end 101a is opened and closed by the following valve operating steps (a) to (g) shown in FIGS. 15(a) and 15(b) as (a) to (g).
(a) The proportional control valve is actuated by an exhaust valve open signal.
(b) Driving oil (pressure source) (pressure p) is sent to the driving hydraulic pump. The hydraulic pressure op of the driving high-pressure oil is applied to the actuator 104 via a high-pressure pipe up to the maximum hydraulic pressure Pomax at the time of valve opening, and the exhaust pipe end 101a begins to open against the gas pressure gp in the combustion chamber, the inertial force of the exhaust valve stem 103, and the force of the air spring 105.
(c) In the process of opening the exhaust pipe end 101a, the gas pressure gp in the combustion chamber decreases, the inertial force of the exhaust valve rod 103 also decreases, and the oil pressure op of the driving high-pressure oil decreases.
(d) When the exhaust pipe end 101a approaches the open position (fully open), the exhaust valve rod 103 is decelerated by controlling the force of the air spring 105 and the hydraulic pressure op of the driving high-pressure oil, and the exhaust pipe end 101a reaches the open position (fully open).
(e) After maintaining the exhaust tube end 101a open (fully open), an exhaust valve closing signal is input to the proportional control valve, and the force of the air spring 105 causes the exhaust valve rod 103 to start moving in the direction of closing the exhaust tube end 101a.
(f) Even when the exhaust pipe end 101a approaches closure and the inertial force of the exhaust valve rod 103 becomes negative (-), the force of the air spring 105 continues to act. Therefore, the oil pressure op of the high-pressure driving oil is controlled up to the peak oil pressure Pcmax at the time of valve closure to decelerate the exhaust valve rod 103 and suppress the seating speed of the valve body 102.
(g) The valve element 102 is gently seated on the valve seat 101b by the force of the air spring 105 and the controlled hydraulic pressure op of the high pressure driving oil.

Japanese Utility Model Application Publication No. 64-022805

In the above-described exhaust valve drive device, the drive power consumption is proportional to the value (=p·v) obtained by multiplying the pressure p of the drive oil (pressure source), which is determined by the maximum pressure (Pomax) of the drive high-pressure oil, by the consumed flow rate (v).
Therefore, the driving power consumption can be reduced by lowering the maximum pressure (Pomax) of the driving high-pressure oil to lower the pressure p of the driving oil (pressure source) and/or by reducing the flow rate (v) consumed when the exhaust pipe end 101a is open.

However, the maximum pressure (Pomax) of the driving high-pressure oil needs to be set to a pressure slightly higher than the maximum value of the combustion chamber gas pressure gp generated during the operation of the exhaust valve drive device and the force of the air spring 105. This is because there is a pressure loss from the driving hydraulic pump to the actuator and because the exhaust pipe end 101a needs to be opened against the combustion chamber gas pressure gp and the force of the air spring 105.
In addition, during operation of the exhaust valve drive device, the force of the air spring 105 is set so as not to be defeated by the inertial force generated when the exhaust valve rod 103 is operated, thereby suppressing the occurrence of cavitation in the driving hydraulic system.

Therefore, the maximum pressure (Pomax) of the driving high-pressure oil cannot be reduced. In addition, the consumption flow rate (v) when the exhaust pipe end 101a is opened cannot be reduced if the stroke of the exhaust valve rod 103 is maintained.
Therefore, it is difficult to reduce the driving power consumption in the conventional exhaust valve drive device.

The object of the present invention is to provide an exhaust valve drive device for use in internal combustion engines such as diesel engines, which reduces drive power consumption.

Further objects of the present invention will become apparent from the following description.

The above problems are solved by the following inventions.
1.
An exhaust valve rod having a valve body that opens and closes the exhaust port of the combustion chamber of the internal combustion engine, and supported movably in a closing direction that closes the exhaust port in a direction away from the combustion chamber, and in an opening direction that opens the exhaust port in a direction that enters the combustion chamber.
A hydraulic mechanism that biases the exhaust valve rod in the opening direction;
A first air spring that applies a force in the closing direction to the exhaust valve rod;
A second air spring that applies a force in the closing direction to the exhaust valve rod only in a partial section of the movement range of the exhaust valve rod ranging from a position where the exhaust port is closed to a position where the exhaust port is fully opened.
The second air spring does not apply force to the exhaust valve rod from a position where the exhaust port is closed to a predetermined intermediate position in the opening process where the exhaust port is fully opened, and from the intermediate position in the opening process onwards, a force in the closing direction is applied to decelerate the exhaust valve rod. An exhaust valve drive device characterized by the above.
2.
The exhaust valve drive device according to claim 1, wherein the intermediate position in the opening process is near a position where the inertial force of the exhaust valve rod changes from the closing direction to the opening direction.
3.
An exhaust valve rod having a valve body that opens and closes the exhaust port of the combustion chamber of the internal combustion engine, and supported movably in a closing direction that closes the exhaust port in a direction away from the combustion chamber, and in an opening direction that opens the exhaust port in a direction that enters the combustion chamber.
A hydraulic mechanism that biases the exhaust valve rod in the opening direction;
A first air spring that applies a force in the closing direction to the exhaust valve rod;
A second air spring that applies a force in the closing direction to the exhaust valve rod only in a partial section of the movement range of the exhaust valve rod ranging from a position where the exhaust port is closed to a position where the exhaust port is fully opened.
The second air spring comprises:
From the position where the exhaust port is blocked to a predetermined intermediate position in the opening process where the exhaust port is fully opened, no force is applied to the exhaust valve rod, and from the intermediate position in the opening process onwards, a force in the closing direction is applied to decelerate the exhaust valve rod.
From the position where the exhaust port is fully opened to a predetermined intermediate position in the closing process where the exhaust port is closed, a force in the closing direction is applied to the exhaust valve rod to accelerate the exhaust valve rod, and after the intermediate position in the closing process, No force is applied to the exhaust valve rod. An exhaust valve drive device characterized by the above.
4.
The intermediate position in the opening process is near the position where the inertial force of the exhaust valve rod changes from the closing direction to the opening direction,
The exhaust valve drive device according to claim 3, wherein the intermediate position in the closing process is near a position where the inertial force of the exhaust valve rod changes from the opening direction to the closing direction.
5.
a first annular piston member constituting the first air spring;
a second annular piston member constituting the second air spring,
The first annular piston member is arranged coaxially with the exhaust valve rod on the inner circumferential side of the air spring cylinder around the exhaust valve rod, and has an inner circumferential surface fixed to the exhaust valve rod. An action surface facing the opening direction facing the air spring cylinder, an outer peripheral cylindrical sliding surface coaxial with the exhaust valve rod, and an abutment portion.
The second annular piston member is arranged coaxially with the exhaust valve rod on the outer circumferential side within the air spring cylinder, and its outer peripheral surface is an outer cylindrical sliding surface coaxial with the exhaust valve rod. This outer cylindrical sliding surface is slidable in the axial direction of the exhaust valve rod on the inner circumferential surface of the air spring cylinder, and has an inner cylindrical sliding surface coaxial with the exhaust valve rod, and this inner cylindrical sliding surface is slidable in the axial direction of the exhaust valve rod on the outer cylindrical sliding surface of the first annular piston member. An operating surface facing the opening direction facing the inside of the air spring cylinder, and an abutted portion against which the abutment portion of the first annular piston member abuts in the opening direction.
the first air spring is configured to compress and expand a volume of a sealed space in the air spring cylinder by the first annular piston member,
The second air spring comprises:
The second annular piston member is configured to compress and expand the volume of a sealed space in the air spring cylinder,
When the position of the exhaust valve rod is between the position that closes the exhaust port and the intermediate position, the second annular piston member abuts against the stopper in the air spring cylinder and stops, and the abutting portion is separated from the abutted portion. No force is applied to the exhaust valve rod,
When the position of the exhaust valve rod is between the intermediate position and the position where the exhaust port is opened, the abutment portion abuts the abutted portion, causing the second annular piston member to move together with the first annular piston member. The exhaust valve drive device according to any one of 1 to 4, characterized in that a force is applied to the exhaust valve rod via the first annular piston member.
6.
6. The exhaust valve drive device according to item 5, wherein a hydraulic damper is provided on either the contact portion or the contacted portion.
7.
The first annular piston member has a cylindrical portion fixedly attached to the exhaust valve rod and a disk portion formed protruding from the opening direction side portion of the cylindrical portion toward the outer circumferential side, and the opening direction side surface of the disk portion is the working surface, the outer peripheral surface of the disk portion is the outer circumferential cylindrical sliding surface, and the abutment portion is on the outer circumferential side portion of the working surface.
6. The exhaust valve drive device described in item 5, wherein the second annular piston member has a cylindrical portion slidable on the inner peripheral surface of the air spring cylinder, a disk portion protruding inward from the opening direction side of the cylindrical portion, and an inner cylindrical portion protruding in the closing direction from the closing direction side surface of the disk portion, wherein the opening direction side surface of the disk portion is the operating surface, the outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, the inner peripheral surface of the inner cylindrical portion is the inner peripheral cylindrical sliding surface, and the abutted portion is located inner than the inner cylindrical portion on the closing direction side surface of the disk portion.
8.
The first annular piston member has a disk portion fixedly attached to the exhaust valve rod, a cylindrical portion formed protruding from the outer peripheral portion of the disk portion toward the closing direction, and an outer peripheral disk portion formed protruding from the closing direction side portion of the cylindrical portion toward the outer peripheral side, and the surface of the disk portion on the opening direction side is the working surface, the outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, and the abutment portion is on the surface on the opening direction side of the outer peripheral disk portion,
The second annular piston member comprises:
6. The exhaust valve drive device according to item 5, characterized in that it comprises a cylindrical portion slidable on the inner peripheral surface of the air spring cylinder, a disk portion formed to protrude inward from the closing direction side portion of the cylindrical portion toward the inner peripheral side, and an inner cylindrical portion formed to protrude from the inner peripheral portion of the disk portion toward the closing direction, wherein the opening direction side surfaces of the cylindrical portion and the disk portion are the operating surface, the outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, the inner peripheral surface of the inner cylindrical portion is the inner peripheral cylindrical sliding surface, and the abutted portion is located on the closing direction side end surface of the inner cylindrical portion.

The present invention provides an exhaust valve drive device for use in internal combustion engines such as diesel engines, which reduces drive power consumption.

FIG. 1 is a block diagram showing a schematic configuration of an exhaust valve drive device according to the present invention. FIG. 1 is a vertical cross-sectional view showing the overall configuration of an exhaust valve drive device according to a first embodiment. FIG. 1 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of an exhaust valve drive device according to a first embodiment. FIG. 1 is a vertical cross-sectional view showing a schematic configuration (at an intermediate position) of an exhaust valve drive device according to a first embodiment. FIG. 1 is a vertical cross-sectional view showing a schematic configuration (valve open state) of an exhaust valve drive device according to a first embodiment. 1 is a cross-sectional view showing the shapes of first and second annular piston members of the first embodiment; FIG. 1 is a vertical cross-sectional view schematically illustrating a configuration of a hydraulic damper according to a first embodiment. 1A is a graph showing an exhaust valve acting force pattern and an opening degree of a valve element in an exhaust valve drive device of an embodiment; FIG. 1B is a graph showing a pressure change of high-pressure oil for driving and an opening degree of a valve element in an exhaust valve drive device of an embodiment; FIG. 10 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of an exhaust valve drive device according to a second embodiment. FIG. 10 is a longitudinal cross-sectional view showing a schematic configuration (at an intermediate position) of an exhaust valve drive device according to a second embodiment. FIG. 10 is a vertical cross-sectional view showing a schematic configuration (valve open state) of an exhaust valve drive device according to a second embodiment. 10 is a cross-sectional view showing the shapes of first and second annular piston members of the second embodiment; FIG. 10 is a vertical cross-sectional view schematically showing the configuration of a stopper hydraulic damper according to a second embodiment. FIG. 1 is a vertical cross-sectional view showing the configuration of a conventional exhaust valve drive device. Graph (a) showing the exhaust valve acting force pattern and the valve element opening in a conventional exhaust valve drive device; Graph (b) showing the pressure change of the driving high-pressure oil and the valve element opening in a conventional exhaust valve drive device;

[General configuration of exhaust valve drive device]
The general configuration of the exhaust valve drive device according to the present invention will be described below.

The exhaust valve drive device of the present invention is particularly suitable for use in internal combustion engines such as diesel engines installed on ships.

Figure 1 is a block diagram showing the general configuration of an exhaust valve drive system according to the present invention.

As shown in Figure 1, the exhaust valve drive device of the present invention is a device that opens and closes the exhaust port and is configured to include a drive hydraulic pump 8 that constitutes a hydraulic mechanism, an exhaust valve stem 3 that is driven by the hydraulic pressure of the drive high-pressure oil sent from this drive hydraulic pump 8 and opens and closes the exhaust port of the combustion chamber (not shown), and a housing 10 that movably supports this exhaust valve stem 3.

The drive hydraulic pump 8 has a proportional control valve 9, and when an exhaust valve open signal or exhaust valve close signal is sent from the engine control device 11 to this proportional control valve 9, drive oil (pressure source) is supplied via the proportional control valve 9. Drive oil (pressure source) is supplied to the proportional control valve 9 through a supply pipe 17 having a drive oil inlet accumulator (pressure accumulator) 17a, and the drive oil (pressure source) is discharged through a discharge pipe 16 having a drive oil outlet accumulator 16a. The drive hydraulic pump 8 uses the supplied drive oil (pressure source) to feed and discharge high-pressure drive oil. The drive hydraulic pump 8 can be made more compact by increasing the pressure P of the drive oil (pressure source), reducing the diameter of the drive hydraulic pump 8's cylinder, and reducing the pressure of the drive oil to use it as high-pressure drive oil.

High-pressure driving oil delivered from the driving hydraulic pump 8 is sent to the housing 10 via the high-pressure pipe 12, driving the actuator 4. The actuator 4, driven by the high-pressure driving oil, operates integrally with the exhaust valve stem 3, biasing it in the opening direction to open the exhaust port of the combustion chamber.

As shown in Figure 1, a first air spring 5a and a second air spring 5b are provided within the housing 10 around the shaft portion 3a of the exhaust valve stem 3.

The first air spring 5a has a first annular piston member 7 fixedly attached to the shaft portion 3a of the exhaust valve rod 3. As the exhaust valve rod 3 moves, the first annular piston member 7 compresses and expands the volume of the sealed space within the air spring cylinder 6 around the shaft portion 3a.

The second air spring 5b has a second annular piston member 14 that is arranged axially movable relative to the shaft portion 3a of the exhaust valve rod 3. An abutment member 13 is fixedly attached to the shaft portion 3a of the exhaust valve rod 3. The second annular piston member 14 has an abutment portion against which the abutment member 13 abuts. The second annular piston member 14 compresses the volume of the sealed space within the air spring cylinder 6 when the abutment member 13 abuts against the abutment portion and the exhaust valve rod 3 moves in the opening direction (arrow O in Figure 2).

In the closed valve state, in which the valve disc 2 closes the exhaust tube end 1a, the abutting member 13 is separated from the abutted portion of the second annular piston member 14. At this time, the second air spring 5b does not apply force to the exhaust valve stem 3.

When the exhaust valve stem 3 moves in the opening direction (arrow O in Figure 1), the abutment member 13 approaches the abutted portion, and when the exhaust valve stem 3 reaches a predetermined intermediate position described below, the abutment member 13 abuts against the abutted portion. When the exhaust valve stem 3 moves further in the opening direction, the abutment member 13 moves the second annular piston member 14, compressing the volume of the sealed space within the air spring cylinder 6. At this time, the second air spring 5b applies a force to the exhaust valve stem 3 via the abutment member 13 in the closing direction (arrow C in Figure 1), causing the valve disc 2 to close the exhaust tube end 1a.

First Embodiment
Preferred embodiments of the present invention will now be described.

[Overall configuration of the exhaust valve drive device]
The overall configuration of the exhaust valve drive device of the first embodiment will now be described.
FIG. 2 is a vertical cross-sectional view showing the overall configuration of the exhaust valve drive device of the first embodiment.

As shown in Figure 2, this exhaust valve drive device is installed over the exhaust port of the combustion chamber and includes a housing 10 having an exhaust tube 1 that guides exhaust from the exhaust port. The end of the exhaust tube 1, called exhaust tube end 1a, is butted against the exhaust port of the combustion chamber. Exhaust gas is exhausted from the combustion chamber through the exhaust port of the combustion chamber and exhaust tube end 1a, as shown by arrow E in Figure 2.

This exhaust valve drive device includes an exhaust valve rod 3 supported by a housing 10 so that it can move toward and away from the exhaust tube end 1a. The tip of the exhaust valve rod 3 forms a valve body 2 that opens and closes the exhaust tube end 1a, and is driven by a hydraulic mechanism.

The valve disc 2 is disk-shaped and closes the exhaust pipe end 1a by being pressed against the valve seat 1b (the periphery of the circular exhaust pipe end 1a) from the combustion chamber side. The valve disc 2 opens the exhaust pipe end 1a by being moved away from the valve seat 1b toward the combustion chamber.

The exhaust valve rod 3 has its tip, the valve disc 2, positioned within the combustion chamber, and its rod-shaped shaft portion 3a, continuing from the valve disc 2, extending through the exhaust stack 1 and out of the combustion chamber, supported by the housing 10. The valve disc 2 is pressed against the valve seat 1b, as shown by arrow C in Figure 2, by the gas pressure inside the combustion chamber, as shown by arrow GP in Figure 2. The shaft portion 3a of the exhaust valve rod 3 is driven in the direction of entering the combustion chamber (the opening direction, as shown by arrow O), by the hydraulic pressure of the high-pressure driving oil, as shown by arrow OP in Figure 2. Attached to the base end of the exhaust valve rod 3 is an actuator 4 that receives the hydraulic pressure OP of the high-pressure driving oil and moves the exhaust valve rod 3 in the opening direction.

The range of movement of the exhaust valve rod 3 ranges from the position where the valve body 2 closes the exhaust stack end 1a to the position where the exhaust stack end 1a is fully open.

[Shape and structure of the first and second air springs]
The shapes and structures of the first and second air springs of the first embodiment will be described below.
This embodiment embodies the configuration of the first air spring 5a and the second air spring 5b.

FIG. 3 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of the exhaust valve drive device of the first embodiment.
FIG. 4 is a vertical cross-sectional view showing a schematic configuration (at an intermediate position) of the exhaust valve drive device of the first embodiment.
FIG. 5 is a vertical cross-sectional view showing a schematic configuration (valve open state) of the exhaust valve drive device of the first embodiment.
FIG. 6 is a vertical cross-sectional view schematically showing the configuration of the stopper hydraulic damper of the first embodiment.

As shown in Figures 3 to 6, the first air spring 5a is configured with a first annular piston member 7. In this embodiment, the abutment member is integrated with the first annular piston member 7 and forms the abutment portion 13, which is part of the first annular piston member 7.

The first annular piston member 7 is arranged coaxially with the exhaust valve stem 3 on the inner circumferential side of the air spring cylinder 6 around the shaft portion 3a of the exhaust valve stem 3. The first annular piston member 7 is attached with its inner circumferential surface fixed to the exhaust valve stem 3. The first annular piston member 7 has an operating surface (surface that compresses the gas in the air spring cylinder 6) 73 facing the opening direction toward the inside of the air spring cylinder 6, an outer peripheral cylindrical sliding surface 7a coaxial with the exhaust valve stem 3, and an abutment portion 13. Multiple seal rings are attached to the outer peripheral cylindrical sliding surface 7a.

The inner circumferential surface of the first annular piston member 7 is in close contact with the outer circumferential surface of the shaft portion 3a, preventing gas from passing between them.

The first annular piston member 7 has a cylindrical portion 71 fixedly attached to the shaft portion 3 a of the exhaust valve rod 3 .
The first annular piston member 7 has a disk portion 72 formed to protrude outward from the opening direction side portion of the cylindrical portion 71. The surface of this disk portion 72 on the opening direction side is an action surface 73. The abutment portion 13 is located on the outer peripheral portion of this action surface 73. In addition, the outer peripheral surface of the disk portion 72 is the outer peripheral cylindrical sliding surface 7a.

The second air spring 5b is configured with a second annular piston member 14, as shown in Figures 3 to 6.

The second annular piston member 14 is arranged coaxially with the shaft portion 3a of the exhaust valve rod 3 on the outer periphery of the air spring cylinder 6. The outer periphery of the second annular piston member 14 forms an outer periphery cylindrical sliding surface 81 coaxial with the exhaust valve rod 3, and this outer periphery cylindrical sliding surface 81 is able to slide in the axial direction of the shaft portion 3a of the exhaust valve rod 3 against the inner periphery of the air spring cylinder 6. Multiple seal rings are attached to the outer periphery cylindrical sliding surface 81. The second annular piston member 14 has an inner periphery cylindrical sliding surface 14c coaxial with the exhaust valve rod 3, and this inner periphery cylindrical sliding surface 14c is able to slide in the axial direction of the shaft portion 3a of the exhaust valve rod 3 against the outer periphery cylindrical sliding surface 7a of the first annular piston member 7. The second annular piston member 14 has an operating surface 82 (the surface that compresses the gas in the air spring cylinder 6) facing the opening direction toward the inside of the air spring cylinder 6. The second annular piston member 14 has an abutment portion 15 against which the abutment portion 13 of the first annular piston member 7 abuts in the opening direction.

The outer cylindrical sliding surface 81 of the second annular piston member 14 is in close contact with the inner surface of the air spring cylinder 6 and is able to slide in the axial direction of the shaft portion 3a (the opening direction indicated by arrow O and the closing direction indicated by arrow C), preventing gas from passing between them.

The second annular piston member 14 has a cylindrical portion 83 that is slidable on the inner peripheral surface of the air spring cylinder 6. The outer peripheral surface of this cylindrical portion 83 is the outer peripheral cylindrical sliding surface 81.
The second annular piston member 14 has a disk portion 84 formed to protrude inward from the opening direction side portion of the cylindrical portion 83. The surface of the disk portion 84 on the opening direction side is the working surface 82.
The second annular piston member 14 has an inner cylindrical portion 85 formed to protrude in the closing direction from the closing direction side surface of the disk portion 84. The inner peripheral surface of this inner cylindrical portion 85 is the inner cylindrical sliding surface 14c. In addition, the contact portion 15 is located on the inner peripheral side of the inner cylindrical portion 85 on the closing direction side surface of the disk portion 84.

The sum of the axial length (width) of the outer peripheral cylindrical sliding surface 7a of the first annular piston member 7 and the inner peripheral cylindrical sliding surface 14c of the second annular piston member 14 of the shaft portion 3a of the exhaust valve rod 3 corresponds to the sliding range (Figures 3 and 4) of the first annular piston member 7 relative to the second annular piston member 14. Therefore, even when the first annular piston member 7 and the second annular piston member 14 are moved relative to each other within their relative movement range, the outer peripheral cylindrical sliding surface 7a and the inner peripheral cylindrical sliding surface 14c do not separate, and gas does not pass between them.

The air spring cylinder 6 contains an enclosed space formed by the housing 10, the shaft 3a, and the first and second annular piston members 7, 14 on the valve body 2 side of the first and second annular piston members 7, 14. Air pressure indicated by arrow P1 in Figures 2 to 5 is supplied to the air spring cylinder 6, creating a pressure P1.

It is preferable that the area of the acting surface 73 of the first annular piston member 7 be smaller than the area of the acting surface 82 of the second annular piston member 14. As will be described later, the area of the acting surface 73 of the first annular piston member 7 is determined by the air spring force required when only the first air spring 5a is acting.

A stopper 14a is provided within the air spring cylinder 6 against which the second annular piston member 14 abuts, stopping the movement of the second annular piston member 14 in the closing direction (arrow C).

A hydraulic damper 13a is disposed on at least one of the abutting portion 13 of the first annular piston member 7 and the abutted portion 15 of the second annular piston member 14. In this embodiment, the hydraulic damper 13a is disposed on the abutting portion 13 of the first annular piston member 7. In addition, a stopper hydraulic damper 14b is disposed on the stopper 14a at the location where the second annular piston member 14 abuts.

As shown in Figures 3 to 5, the first air spring 5a in this embodiment is configured so that the volume of the sealed space within the air spring cylinder 6, which is located within the housing 10 and around the shaft portion 3a of the exhaust valve stem 3, is compressed and expanded by the operating surface 73 of the first annular piston member 7.

As shown in Figures 4 and 5, the second air spring 5b in this embodiment is configured so that the volume of the sealed space within the air spring cylinder 6 is compressed and expanded by the working surface 82 of the second annular piston member 14.

As shown in Figures 4 and 5, the second annular piston member 14 is movable within a predetermined range relative to the shaft portion 3a in the axial direction of the shaft portion 3a (the opening direction indicated by arrow O and the closing direction indicated by arrow C). Therefore, the first annular piston member 7 and the second annular piston member 14 are movable relative to each other within a predetermined range in the axial direction of the shaft portion 3a.

As shown in Figures 4 and 5, the abutment portion 13 of the first annular piston member 7 abuts against the abutted portion 15 of the second annular piston member 14 in the opening direction (arrow O). When the second annular piston member 14 is stationary, if the first annular piston member 7 moves in the opening direction (arrow O), the abutment portion 13 abuts against the abutted portion 15, as shown in Figure 4. If the first annular piston member 7 moves in the closing direction (arrow C), the abutment portion 13 moves away from the abutted portion 15 in the axial direction of the shaft portion 3a, as shown in Figure 3.

Figure 7 is a vertical cross-sectional view showing the schematic configuration of the hydraulic damper of the first embodiment.

As shown in Figure 7, the hydraulic damper 13a and stopper hydraulic damper 14b are composed of a hydraulic cylinder 18 and a damper piston 19 that can slide within a certain range within the hydraulic cylinder 18. Hydraulic pressure is supplied to the hydraulic cylinder 18 from a hydraulic supply pipe 21 via a check valve 20. This hydraulic pressure is discharged from the hydraulic cylinder 18 as a laminar flow through a hydraulic discharge pipe 22. A constant high pressure is maintained within the hydraulic cylinder 18. When the second annular piston member 14 collides with the tip of the damper piston 19, the kinetic energy of the collision compresses the hydraulic cylinder 18, increasing the pressure, generating a repulsive force that cushions the collision.

In this embodiment, as shown in Figures 3 to 6, oil is supplied to the hydraulic damper 13a from the inner peripheral side via the circumferential surface of the shaft portion 3a from the housing 10. As shown in Figures 3 to 6, oil is supplied to the stopper hydraulic damper 14b from the outer peripheral side of the housing 10. In this embodiment, the hydraulic dampers 13a and stopper hydraulic dampers 14b are arranged in parallel oil supply, and because the damper structure is simple, this arrangement reduces the risk of malfunction.

As shown in Figure 4, when the first annular piston member 7 is moved in the opening direction (arrow O) and the hydraulic damper 13a of the abutting portion 13 abuts against the abutted portion 15 of the second annular piston member 14, the hydraulic flow path formed in the cylindrical portion 71 of the first annular piston member 7 connects to the hydraulic flow path from the outer periphery of the housing 10, and hydraulic pressure from the outer periphery of the housing 10 is supplied to the hydraulic damper 13a via the circumferential surface of the shaft portion 3a.

[Actions and actions]
The operation and function of the first and second air springs will now be described.

The first air spring 5a applies a force to the shaft 3a of the exhaust valve rod 3 in the closing direction (arrow C) away from the combustion chamber, closing the exhaust pipe end 1a (exhaust port), over the entire range of movement of the stroke X1, from the position where the valve body 2 closes the exhaust pipe end 1a to the position where the valve body 2 opens (fully opens) the exhaust pipe end 1a.

The second air spring 5b applies a force in the closing direction (arrow C) to the shaft 3a of the exhaust valve rod 3, closing the exhaust pipe end 1a, only in a portion (Figures 4-5) of the range of movement of the exhaust valve rod 3 (Figures 3-5) that spans between the position where the valve body 2 closes the exhaust pipe end 1a and the position where the exhaust pipe end 1a is fully open.

The second air spring 5b does not apply force to the shaft 3a of the exhaust valve stem 3 in the section (<X1) spanning from the position where the valve body 2 closes the exhaust stack end 1a (Figure 3) to the intermediate position (Figure 4) where the exhaust stack end 1a is at a predetermined opening (0% < opening < 100%).

When the exhaust valve rod 3 is positioned between the position that closes the exhaust port and an intermediate position (Figures 3 and 4), the second air spring 5b abuts against the stopper 14a inside the air spring cylinder 6 and stops. Since the abutting portion 13 of the first annular piston member 7 is spaced apart from the abutted portion 15 in the axial direction of the shaft portion 3a, no force is applied to the shaft portion 3a of the exhaust valve rod 3.

When the position of the exhaust valve rod 3 is between the mid-position and the position that opens the exhaust port (Figures 4 and 5), the second air spring 5b moves together with the first annular piston member 7 because the abutting portion 13 of the first annular piston member 7 abuts the abutted portion 15, and applies force to the shaft portion 3a of the exhaust valve rod 3 via the abutting portion 13 of the first annular piston member 7.

The first air spring 5a decelerates the exhaust valve rod 3 during the opening process, when the exhaust stack end 1a moves from a position where it is closed to a position where it is fully open, and accelerates the exhaust valve rod 3 during the closing process, when the exhaust stack end 1a moves from a position where it is fully open to a position where it is closed.

The second air spring 5b, together with the first air spring 5a, decelerates the exhaust valve rod 3 during the section of the opening process where a force is applied to the shaft 3a, and, together with the first air spring 5a, accelerates the exhaust valve rod 3 during the section of the closing process where a force is applied to the shaft 3a.

During the closing process, when the exhaust pipe end 1a reaches a predetermined opening angle (0% < opening angle < 100%), the second annular piston member 14 comes into contact with the stopper 14a inside the housing 10 and stops, as shown in Figure 4, preventing further expansion inside the air spring cylinder 6. After this point, the abutting portion 13 of the first annular piston member 7 moves away from the abutted portion 15 of the second annular piston member 14 in the axial direction of the shaft portion 3a. When the abutting portion 13 moves away from the abutted portion 15, the second air spring 5b no longer applies force to the exhaust valve stem 3 (becomes inactive).

In other words, during the opening process (Fig. 3 → Fig. 5), the second air spring 5b does not act until the intermediate position, and only the first air spring 5a acts. Furthermore, during the closing process (Fig. 5 → Fig. 3), the second air spring 5b does not act from the intermediate position, and only the first air spring 5a acts.

During the opening process (Fig. 3 → Fig. 5), from the position where the valve body 2 closes the exhaust tube end 1a (Fig. 3) to the intermediate position where the exhaust tube end 1a reaches a predetermined opening (0% < opening < 100%) (Fig. 4), the force applied by the first air spring 5a to the exhaust valve stem 3 is in the closing direction (arrow C), so no negative pressure is generated in the hydraulic pressure OP of the high-pressure driving oil.

During the opening process (Fig. 3 → Fig. 5), the intermediate position (Fig. 4) where the second air spring 5b begins to act and the exhaust pipe end 1a reaches a predetermined opening (0% < opening < 100%) is the position or near that position where the inertial force as the exhaust valve stem 3 moves in the opening direction changes from negative (closing direction) to positive (opening direction).

Furthermore, during the closing process (Fig. 5 → Fig. 3), the intermediate position (Fig. 4) where the second air spring 5b is inactive and the exhaust pipe end 1a reaches a predetermined opening (0% < opening < 100%) is the position or near that position where the inertial force when the exhaust valve stem 3 moves in the closing direction changes from positive (opening direction) to negative (closing direction).

During the closing process (Figure 5 → Figure 3), the exhaust valve stem 3 is decelerated by the deceleration force exerted by the first and second air springs 5a, 5b, reducing the speed at which the valve disc 2 seats on the valve seat 1b and achieving a more gradual seating.

The pressure P of the driving oil (pressure source) depends on the maximum oil pressure (Pomax) generated when the exhaust pipe end 1a is opened, i.e., [(combustion chamber gas pressure GP) + (force of the first air spring 5a) + (inertia force of the exhaust valve rod 3)]. By weakening the air spring force of the first air spring 5a, the maximum oil pressure (Pomax) can be reduced, lowering the pressure P of the driving oil (pressure source), thereby reducing driving power consumption.

When the exhaust stack end 1a is closed, the air spring force of the first air spring 5a can reduce the peak oil pressure (Pcmax), thereby increasing the durability of equipment such as the piston ring of the actuator 4.

FIG. 8A is a graph showing the force acting on the exhaust valve rod 3 (exhaust valve acting force pattern) and the opening degree of the exhaust tube end 1a (valve body 2) in the exhaust valve drive device of the embodiment.
FIG. 8B is a graph showing the pressure change of the high-pressure driving oil and the opening degree of the exhaust tube end 1a (valve element 2) in the exhaust valve drive device of the embodiment.
In FIG. 8A, the opening direction of the exhaust pipe end 1a is shown as positive (+) and the closing direction is shown as negative (-). The opening degree of the exhaust pipe end 1a (valve body 2) (dashed line), the inertial force of the exhaust valve rod 3 (dash-dotted line), the combustion chamber gas pressure GP acting on the valve body 2 (dash-dotted line), the force of the first air spring 5a (solid line), and the sum of the forces of the first and second air springs 5b (solid line) are shown.
In FIG. 8(b), the opening direction of the exhaust pipe end 1a is indicated by a positive (+) sign and the closing direction is indicated by a negative (-) sign, and the pressure of the high pressure oil for driving is shown (thin line).

In this exhaust valve drive device, the exhaust tube end 1a is opened and closed through the following valve operating steps (A) to (G) shown in FIGS. 8(a) and 8(b) as (A) to (G).
(A) The proportional control valve 9 is operated by an exhaust valve open signal.
(B) Driving oil (pressure source) is sent to the driving hydraulic pump 8. The hydraulic pressure OP of the driving high-pressure oil is applied to the actuator 4 via the high-pressure pipe 12 up to the maximum hydraulic pressure Pomax at the time of valve opening, and the exhaust pipe end 1a begins to open against the gas pressure GP in the combustion chamber, the inertial force of the exhaust valve rod 3, and the force of the first air spring 5a.
At this time, the force of the first air spring 5a is weak, so the force required for the valve opening operation (hydraulic pressure OP of the driving high-pressure oil) can be reduced, and driving power consumption can be reduced.
(C) In the process of opening the exhaust pipe end 1a, the gas pressure GP in the combustion chamber decreases, the inertial force of the exhaust valve rod 3 also decreases, and the hydraulic pressure OP of the driving high-pressure oil decreases. In the latter half of the process of opening the exhaust pipe end 1a, the force of the second air spring 5b also begins to act, decelerating the valve speed.
(D) When the exhaust pipe end 1a approaches the open position (fully open), the exhaust valve rod 3 is decelerated by controlling the sum of the forces of the first and second air springs 5a, 5b and the hydraulic pressure OP of the driving high-pressure oil, and the exhaust pipe end 1a is opened (fully open).
(E) After maintaining the exhaust pipe end 1a open (fully open), an exhaust valve closing signal is input to the proportional control valve 9, and the exhaust valve rod 3 begins to move in the direction to close the exhaust pipe end 1a due to the sum of the forces of the first and second air springs 5a and 5b. At this time, the exhaust valve rod 3 is accelerated by the sum of the forces of the first and second air springs 5a and 5b.
(F) As the exhaust pipe end 1a approaches closure and the inertial force of the exhaust valve rod 3 becomes negative (closing direction (-)), the second air spring 5b becomes inactive and the force accelerating the exhaust valve rod 3 weakens. The oil pressure OP of the driving high-pressure oil is controlled up to the peak oil pressure Pcmax at the time of valve closure to decelerate the exhaust valve rod 3 and suppress the seating speed of the valve body 2.
At this time, since the force of the first air spring 5a is weak, the force required to decelerate the exhaust valve rod 3 (hydraulic pressure OP of the driving high-pressure oil) can be reduced, and the durability of the equipment (for example, the piston ring of the actuator 4, etc.) can be increased.
(G) The valve element 2 is gently seated on the valve seat 1b by the controlled hydraulic pressure OP of the high-pressure driving oil.

In this exhaust valve drive device, the drive power consumption is proportional to the product (=P·V) of the pressure P of the drive oil (pressure source) determined by the maximum pressure (Pomax) of the drive high-pressure oil and the consumed flow rate (V).
Therefore, the driving power consumption can be reduced by lowering the maximum pressure (Pomax) of the driving high-pressure oil and/or by reducing the flow rate (V) consumed when the exhaust pipe end 1a is open.

In this exhaust valve drive device, the maximum pressure (Pomax) of the high-pressure drive oil can be made lower than in the past because the force of the first air spring 5a is weak and the second air spring 5b is inactive, and the pressure P of the drive oil (pressure source) can be reduced. Therefore, in this exhaust valve drive device, the drive power consumption can be reduced.
In the embodiment shown in Figure 8, it can be seen that the maximum pressure (Pomax) is suppressed to about 70% of that of the conventional exhaust valve drive device shown in Figure 15. Therefore, it can be seen that the exhaust valve drive device according to the present invention can suppress drive power consumption.

Second Embodiment
[Shape and structure of the first and second air springs]
The shapes and structures of the first and second air springs of the second embodiment will be described below.
The overall configuration of the exhaust valve drive device is the same as that of the first embodiment, and therefore the description will be omitted here.

FIG. 9 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of an exhaust valve drive device according to the second embodiment.
FIG. 10 is a vertical cross-sectional view showing a schematic configuration (at an intermediate position) of an exhaust valve drive device according to the second embodiment.
FIG. 11 is a vertical cross-sectional view showing a schematic configuration (valve open state) of an exhaust valve drive device according to the second embodiment.
FIG. 12 is a cross-sectional view showing the shapes of the first and second annular piston members of the second embodiment.

In this embodiment, as shown in Figures 9 to 12, the abutment member is integrated with the first annular piston member 7 and forms the abutment portion 13, which is part of the first annular piston member 7.

9 to 12, the first annular piston member 7 has a disk portion 72 fixedly attached to the shaft portion 3a of the exhaust valve rod 3. The surface of the disk portion 72 on the opening side is the working surface 73.
The first annular piston member 7 has a cylindrical portion 71 formed to protrude in the closing direction from the outer peripheral portion of the disk portion 72. The outer peripheral surface of this cylindrical portion 71 is an outer peripheral cylindrical sliding surface 7a. A plurality of seal rings are attached to the outer peripheral cylindrical sliding surface 7a.
The first annular piston member 7 has an outer peripheral disk portion 74 formed to protrude outward from the closing direction side portion of the cylindrical portion 71. The abutment portion 13 is provided on the opening direction side surface of this outer peripheral disk portion 74.

9 to 12, the second annular piston member 14 has a cylindrical portion 83 that is slidable on the inner peripheral surface of the air spring cylinder 6. The outer peripheral surface of this cylindrical portion 83 is an outer peripheral cylindrical sliding surface 81. A plurality of seal rings are attached to the outer peripheral cylindrical sliding surface 81.
The second annular piston member 14 has a disk portion 84 formed to protrude inward from the closing direction side of the cylindrical portion 83. The surfaces of the cylindrical portion 83 and the disk portion 84 on the opening direction side are working surfaces 82.
The second annular piston member 14 has an inner cylindrical portion 85 that protrudes in the closing direction from the inner peripheral portion of the disk portion 84. The inner peripheral surface of this inner cylindrical portion 85 is the inner cylindrical sliding surface 14c. The abutment portion 15 is located on the end surface of the inner cylindrical portion 85 in the closing direction.

In this embodiment, the hydraulic damper 13a is disposed on the abutted portion 15 of the second annular piston member 14, rather than on the abutting portion 13 of the first annular piston member 7.

Figure 13 is a vertical cross-sectional view showing the schematic configuration of the stopper hydraulic damper of the second embodiment.

In this embodiment, as shown in Figures 9 and 13, timing oil supply to the hydraulic damper 13a is performed via the stopper hydraulic damper 14b.

As in the previously described embodiment, the stopper hydraulic damper 14b is composed of a hydraulic cylinder 18 and a damper piston 19 that can slide within a certain range within the hydraulic cylinder 18. Hydraulic pressure is supplied to the hydraulic cylinder 18 from a hydraulic supply pipe 21 via a check valve 20. This hydraulic pressure is discharged from the hydraulic cylinder 18 as a laminar flow through a hydraulic discharge pipe 22.

In this embodiment, as shown in Figure 13, the stopper hydraulic damper 14b has a hydraulic flow path 23 drilled within the damper piston 19. The hydraulic flow path 23 is formed from the surface of the damper piston 19 facing the inside of the hydraulic cylinder 18 (the surface that receives hydraulic pressure) to the outer surface of the damper piston 19 that slides against the inner surface of the hydraulic cylinder 18. An oil supply flow path 24 that is connected to the hydraulic flow path 23 and extends outward is provided on the side of the hydraulic cylinder 18.

A hydraulic flow path 23 is connected to the hydraulic cylinder 18. When the damper piston 19 is in a predetermined position relative to the hydraulic cylinder 18, the outer end of the hydraulic flow path 23 is connected to the oil supply flow path 24, and the hydraulic pressure within the hydraulic cylinder 18 is supplied to the hydraulic damper 13a via the hydraulic flow path 23 and the oil supply flow path 24, as shown in Figures 9 and 10.

In this embodiment, as shown in Figures 9 to 12, oil is supplied to the hydraulic damper 13a from the outer periphery, via the housing 10 and the stopper hydraulic damper 14b. As shown in Figures 9 to 12, oil is supplied to the stopper hydraulic damper 14b from the outer periphery of the housing 10. In this embodiment, the hydraulic damper 13a and the stopper hydraulic damper 14b are arranged in series for oil supply, which is structurally simple and allows for a lighter moving part weight.

As shown in Figures 9, 10, and 12, when the second annular piston member 14 is in the closing direction (arrow C) and not being moved, the second annular piston member 14 abuts against the stopper hydraulic damper 14b, and the hydraulic flow path formed from the disk portion 84 to the inner cylindrical portion 85 of the second annular piston member 14 connects to the hydraulic flow path inside the housing 10 from the stopper hydraulic damper 14b, and hydraulic pressure from the stopper hydraulic damper 14b is supplied to the hydraulic damper 13a.

The space between the seal rings on the outer cylindrical sliding surface 81 of the second annular piston member 14 is open to the atmosphere to prevent leakage of pressure P1 from the air spring cylinder 6 from affecting the hydraulic flow path.

As shown in Figure 10, when the second annular piston member 14 collides with the tip of the damper piston 19 of the stopper hydraulic damper 14b, the kinetic energy of the collision compresses the hydraulic cylinder 18, increasing the pressure, generating a repulsive force and cushioning the collision. Also, when the first annular piston member 7 collides with the tip of the damper piston 19 of the hydraulic damper 13a, the kinetic energy of the collision compresses the hydraulic cylinder 18, increasing the pressure, generating a repulsive force and cushioning the collision.

As shown in Figure 9, oil is supplied to the stopper hydraulic damper 14b from the outer periphery of the housing 10. In this embodiment, oil is supplied to the hydraulic damper 13a from the outer periphery via the stopper hydraulic damper 14b at timing. When the hydraulic damper 13a is in a position where it may collide with the first annular piston member 7 (Figures 9 and 10), a flow path is connected from the hydraulic cylinder 18 of the stopper hydraulic damper 14b to the hydraulic damper 13a, and oil is supplied to the hydraulic damper 13a.

[Actions and actions]
The operation and function of the first and second air springs will now be described.

In this embodiment, too, the first air spring 5a applies a force to the shaft portion 3a of the exhaust valve rod 3 in the closing direction (arrow C) away from the combustion chamber, closing the exhaust pipe end 1a (exhaust port), over the entire range of movement of the stroke X1, from the position where the valve body 2 closes the exhaust pipe end 1a to the position where the valve body 2 opens (fully opens) the exhaust pipe end 1a.

In this embodiment, the second air spring 5b also applies a force in the closing direction (arrow C) to the shaft 3a of the exhaust valve rod 3 to close the exhaust tube end 1a in only a portion (Figures 10-11) of the range of movement of the exhaust valve rod 3 (Figures 9-11) that spans between the position where the valve body 2 closes the exhaust tube end 1a and the position where the exhaust tube end 1a is fully open.

The first air spring 5a decelerates the exhaust valve rod 3 during the opening process, when the exhaust stack end 1a moves from a position where it is closed to a position where it is fully open, and accelerates the exhaust valve rod 3 during the closing process, when the exhaust stack end 1a moves from a position where it is fully open to a position where it is closed.

The second air spring 5b, together with the first air spring 5a, decelerates the exhaust valve rod 3 during the section of the opening process where a force is applied to the shaft 3a, and, together with the first air spring 5a, accelerates the exhaust valve rod 3 during the section of the closing process where a force is applied to the shaft 3a.

During the closing process, when the exhaust pipe end 1a reaches a predetermined opening angle (0% < opening angle < 100%), the second annular piston member 14 abuts against the stopper 14a and stops as shown in Figure 10, preventing further expansion inside the air spring cylinder 6. After this, the abutting portion 13 of the first annular piston member 7 moves away from the abutted portion 15 of the second annular piston member 14 in the axial direction of the shaft portion 3a, as shown in Figure 9. When the abutting portion 13 moves away from the abutted portion 15, the second air spring 5b no longer applies force to the exhaust valve stem 3 (becomes inactive).

During the opening process (Figures 9 → 11), the intermediate position (Figure 10) where the second air spring 5b begins to act and the exhaust pipe end 1a reaches a predetermined opening angle (0% < opening angle < 100%) is the position or near that position where the inertial force as the exhaust valve stem 3 moves in the opening direction changes from negative (closing direction) to positive (opening direction).

Furthermore, during the closing process (Fig. 11 → Fig. 9), the intermediate position (Fig. 10) where the second air spring 5b is inactive and the exhaust pipe end 1a reaches a predetermined opening (0% < opening < 100%) is the position or near that position where the inertial force when the exhaust valve stem 3 moves in the closing direction changes from positive (opening direction) to negative (closing direction).

During the closing process (Figure 11 → Figure 9), the exhaust valve stem 3 is decelerated by the deceleration force exerted by the first and second air springs 5a, 5b, reducing the speed at which the valve disc 2 seats on the valve seat 1b and achieving a more gradual seating.

In this embodiment, the force acting on the exhaust valve stem 3 (exhaust valve acting force pattern) and the opening of the exhaust tube end 1a (valve element 2) are as shown in Figure 8(a), and the pressure change of the driving high-pressure oil and the opening of the exhaust tube end 1a (valve element 2) are as shown in Figure 8(b).

In other words, the pressure P of the driving oil (pressure source) depends on the maximum oil pressure (Pomax) generated when the exhaust pipe end 1a is opened, that is, [(combustion chamber gas pressure GP) + (force of the first air spring 5a) + (inertia force of the exhaust valve rod 3)]. By weakening the air spring force of the first air spring 5a, the maximum oil pressure (Pomax) can be reduced, lowering the pressure P of the driving oil (pressure source), and reducing driving power consumption.

Furthermore, when the exhaust stack end 1a is blocked, the air spring force of the first air spring 5a can reduce the peak value of the oil pressure (Pcmax), thereby increasing the durability of equipment such as the piston ring of the actuator 4.

The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention.
Furthermore, it goes without saying that the specific detailed structure, numerical values, and control contents of the control device can be changed as appropriate.
Furthermore, the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include all modifications within the meaning and scope of the claims.

DESCRIPTION OF SYMBOLS 1 Exhaust tube 1a Exhaust tube end 2 Valve body 3 Exhaust valve stem 4 Actuator 5a First air spring 5b Second air spring 6 Air spring cylinder 7 First annular piston member 7a Outer peripheral cylindrical sliding surface 8 Driving hydraulic pump 9 Proportional control valve 10 Housing 11 Engine control device 12 High-pressure pipe 13 Contact portion (contact member)
13a Hydraulic damper 14 Second annular piston member 14a Stopper 14b Stopper hydraulic damper 14c Inner peripheral cylindrical sliding surface 15 Contacted portion 71 Cylindrical portion 72 Disk portion 73 Action surface 74 Outer peripheral disk portion 81 Outer peripheral cylindrical sliding surface 82 Action surface 83 Cylindrical portion 84 Disk portion 85 Inner peripheral cylindrical portion

Claims (8)

An exhaust valve rod having a valve body that opens and closes the exhaust port of the combustion chamber of the internal combustion engine, and supported movably in a closing direction that closes the exhaust port in a direction away from the combustion chamber, and in an opening direction that opens the exhaust port in a direction that enters the combustion chamber.
A hydraulic mechanism that biases the exhaust valve rod in the opening direction;
A first air spring that applies a force in the closing direction to the exhaust valve rod;
A second air spring that applies a force in the closing direction to the exhaust valve rod only in a partial section of the movement range of the exhaust valve rod ranging from a position where the exhaust port is closed to a position where the exhaust port is fully opened.
The second air spring does not apply force to the exhaust valve rod from a position where the exhaust port is closed to a predetermined intermediate position in the opening process where the exhaust port is fully opened, and from the intermediate position in the opening process onwards, a force in the closing direction is applied to decelerate the exhaust valve rod. An exhaust valve drive device characterized by the above. The exhaust valve drive device according to claim 1, wherein the intermediate position in the opening process is near a position where the inertial force of the exhaust valve rod changes from the closing direction to the opening direction. An exhaust valve rod having a valve body that opens and closes the exhaust port of the combustion chamber of the internal combustion engine, and supported movably in a closing direction that closes the exhaust port in a direction away from the combustion chamber, and in an opening direction that opens the exhaust port in a direction that enters the combustion chamber.
A hydraulic mechanism that biases the exhaust valve rod in the opening direction;
A first air spring that applies a force in the closing direction to the exhaust valve rod;
A second air spring that applies a force in the closing direction to the exhaust valve rod only in a partial section of the movement range of the exhaust valve rod ranging from a position where the exhaust port is closed to a position where the exhaust port is fully opened.
The second air spring comprises:
From the position where the exhaust port is blocked to a predetermined intermediate position in the opening process where the exhaust port is fully opened, no force is applied to the exhaust valve rod, and from the intermediate position in the opening process onwards, a force in the closing direction is applied to decelerate the exhaust valve rod.
From the position where the exhaust port is fully opened to a predetermined intermediate position in the closing process where the exhaust port is closed, a force in the closing direction is applied to the exhaust valve rod to accelerate the exhaust valve rod, and after the intermediate position in the closing process, No force is applied to the exhaust valve rod. An exhaust valve drive device characterized by the above. The intermediate position in the opening process is near the position where the inertial force of the exhaust valve rod changes from the closing direction to the opening direction,
The exhaust valve drive device according to claim 3, wherein the intermediate position in the closing process is near a position where the inertial force of the exhaust valve rod changes from the opening direction to the closing direction. a first annular piston member constituting the first air spring;
a second annular piston member constituting the second air spring,
The first annular piston member is arranged coaxially with the exhaust valve rod on the inner circumferential side of the air spring cylinder around the exhaust valve rod, and has an inner circumferential surface fixed to the exhaust valve rod. An action surface facing the opening direction facing the air spring cylinder, an outer peripheral cylindrical sliding surface coaxial with the exhaust valve rod, and an abutment portion.
The second annular piston member is arranged coaxially with the exhaust valve rod on the outer circumferential side within the air spring cylinder, and its outer peripheral surface is an outer cylindrical sliding surface coaxial with the exhaust valve rod. This outer cylindrical sliding surface is slidable in the axial direction of the exhaust valve rod on the inner circumferential surface of the air spring cylinder, and has an inner cylindrical sliding surface coaxial with the exhaust valve rod, and this inner cylindrical sliding surface is slidable in the axial direction of the exhaust valve rod on the outer cylindrical sliding surface of the first annular piston member. An operating surface facing the opening direction facing the inside of the air spring cylinder, and an abutted portion against which the abutment portion of the first annular piston member abuts in the opening direction.
the first air spring is configured to compress and expand a volume of a sealed space in the air spring cylinder by the first annular piston member,
The second air spring comprises:
The second annular piston member is configured to compress and expand the volume of a sealed space in the air spring cylinder,
When the position of the exhaust valve rod is between the position that closes the exhaust port and the intermediate position, the second annular piston member abuts against the stopper in the air spring cylinder and stops, and the abutting portion is separated from the abutted portion. No force is applied to the exhaust valve rod,
When the position of the exhaust valve rod is between the intermediate position and the position where the exhaust port is opened, the abutting portion abuts the abutted portion, thereby causing the second annular piston member to move together with the first annular piston member. The exhaust valve drive device according to any one of claims 1 to 4, characterized in that a force is applied to the exhaust valve rod via the first annular piston member. 6. The exhaust valve drive device according to claim 5, wherein a hydraulic damper is provided on either the contact portion or the contacted portion. The first annular piston member has a cylindrical portion fixedly attached to the exhaust valve rod and a disk portion formed protruding from the opening direction side portion of the cylindrical portion toward the outer circumferential side, and the opening direction side surface of the disk portion is the working surface, the outer peripheral surface of the disk portion is the outer circumferential cylindrical sliding surface, and the abutment portion is on the outer circumferential side portion of the working surface.
6. The exhaust valve drive device according to claim 5, wherein the second annular piston member has a cylindrical portion slidable on the inner peripheral surface of the air spring cylinder, a disk portion protruding inward from the opening direction side of the cylindrical portion, and an inner cylindrical portion protruding in the closing direction from the closing direction side surface of the disk portion, wherein the opening direction side surface of the disk portion is the operating surface, the outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, the inner peripheral surface of the inner cylindrical portion is the inner peripheral cylindrical sliding surface, and the abutted portion is located on the closing direction side surface of the disk portion more inner than the inner cylindrical portion. The first annular piston member has a disk portion fixedly attached to the exhaust valve rod, a cylindrical portion formed protruding from the outer peripheral portion of the disk portion toward the closing direction, and an outer peripheral disk portion formed protruding from the closing direction side portion of the cylindrical portion toward the outer peripheral side, and the surface of the disk portion on the opening direction side is the working surface, the outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, and the abutment portion is on the surface on the opening direction side of the outer peripheral disk portion,
6. The exhaust valve drive device according to claim 5, wherein the second annular piston member has a cylindrical portion slidable on the inner peripheral surface of the air spring cylinder, a disk portion protruding inward from the closing direction side of the cylindrical portion, and an inner cylindrical portion protruding from the inner peripheral portion of the disk portion in the closing direction, wherein a surface of the cylindrical portion on the opening direction side and a surface of the disk portion on the opening direction side are the working surface, an outer peripheral surface of the cylindrical portion is the outer peripheral cylindrical sliding surface, an inner peripheral surface of the inner cylindrical portion is the inner peripheral cylindrical sliding surface, and the abutted portion is located on an end surface of the inner cylindrical portion on the closing direction side.