Exhaust valve drive unit

Abstract

To provide an exhaust valve drive device to be used in an internal combustion engine such as a diesel engine, for suppressing drive consumption power.SOLUTION: The exhaust valve drive device includes: an exhaust valve rod 3 for opening / closing an exhaust port of a combustion chamber; a hydraulic mechanism 8 for energizing the exhaust valve rod 3 in an opening direction; a first air spring 5a for energizing the exhaust valve rod 3 in a closing direction; and a second air spring 5b for energizing the exhaust valve rod 3 in the opening direction. The second air spring 5b energizes the exhaust valve rod 3 to be accelerated only within a partial section of a movement range of the exhaust valve rod 3, but does not energize the exhaust valve rod 3 outside the partial section.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an exhaust valve drive device, and more particularly to an exhaust valve drive device used in an internal combustion engine such as a diesel engine, which reduces drive power consumption. [Background technology]

[0002] In internal combustion engines such as diesel engines, an exhaust valve drive device is used to exhaust gas from an exhaust port of the combustion chamber after fuel is burned (exploded) in the combustion chamber, as described in Patent Document 1.

[0003] As shown in Fig. 6, a conventional exhaust valve drive device is installed over the exhaust port of a combustion chamber (not shown) and includes a housing 100 having an exhaust tube 101 that guides exhaust from the exhaust port. An exhaust tube end 101a, which is the end of the exhaust tube 101, 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 Fig. 6.

[0004] This exhaust valve drive device includes an exhaust valve rod 103 that is supported by a housing 100 so as to be movable in the direction toward and away from an 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.

[0005] The valve element 102 is disk-shaped and closes the exhaust pipe end 101a by being pressed against the valve seat 101b (the periphery of the circular exhaust pipe end 101a) from the combustion chamber side. The valve element 102 opens the exhaust pipe end 101a by moving the valve seat 101b away from the combustion chamber side.

[0006] The exhaust valve rod 103 has a valve disc 102, which is the tip portion, positioned within the combustion chamber, and a rod-shaped shaft portion 103a continuing from the valve disc 102, which extends through the exhaust stack 101 to the outside of the combustion chamber and is supported by the housing 100. The valve disc 102 is pressed against the valve seat 101b as shown by the arrow c in FIG. 6 by the gas pressure in the combustion chamber, as shown by the arrow gp in FIG. 6. The shaft portion 103a of the exhaust valve rod 103 is driven toward the combustion chamber (the opening direction shown by the arrow o) by the hydraulic pressure of the high-pressure driving oil, as shown by the arrow op in FIG. 6. An actuator 104 is attached to the base end portion of the exhaust valve rod 103, which receives the hydraulic pressure op of the high-pressure driving oil and moves the exhaust valve rod 103 in the opening direction.

[0007] An air spring 105 is provided on the exhaust valve rod 103. The air spring 105 is configured to compress and expand the volume of the sealed space in an air spring cylinder 106 provided around the exhaust valve rod 103 by an annular piston 107 attached to the exhaust valve rod 103. Air is supplied into the air spring cylinder 106 as shown by arrow p1 in FIG. 6, and the air pressure increases.

[0008] In this exhaust valve drive device, high-pressure drive oil is pumped in and out of a drive hydraulic pump (not shown), and this high-pressure drive oil is sent through a high-pressure pipe to drive an actuator 104. The actuator 104, driven by the high-pressure drive oil, operates integrally 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 an exhaust valve close signal sent from an engine control device (not shown).

[0009] FIG. 7(a) is a graph showing the force acting on the exhaust valve stem 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. 7(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 7(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. 7(b), the opening direction of the exhaust stack end 101a is indicated by positive (+) and the closing direction is indicated by negative (-), and the pressure of the high-pressure oil for driving (thin line) is shown.

[0010] 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. 7(a) and 7(b) as (a) to (g). (a) The proportional control valve is operated by the exhaust valve open signal. (b) Driving oil (pressure source) (pressure p) is sent to the driving hydraulic pump. Through the high-pressure pipe, the hydraulic pressure op of the driving high-pressure oil is applied to the actuator 104 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 stem 103 also decreases, and the oil pressure op of the high-pressure driving 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 pipe 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 begin moving in the direction of closing the exhaust pipe 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 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 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. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Utility Model Application Publication No. 64-022805 Summary of the Invention [Problem to be solved by the invention]

[0012] In the above-described 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), which is 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 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.

[0013] 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 stem 103 is operated. It is necessary to suppress the occurrence of cavitation in the drive hydraulic system.

[0014] Therefore, the maximum pressure (Pomax) of the driving high-pressure oil cannot be reduced too much. Also, the consumption flow rate (v) when the exhaust pipe end 101a is open cannot be reduced if the stroke of the exhaust valve stem 103 is maintained. Therefore, it is difficult to reduce the driving power consumption in the conventional exhaust valve drive device.

[0015] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an exhaust valve drive device for use in an internal combustion engine such as a diesel engine, which has reduced drive power consumption.

[0016] Further objects of the present invention will become apparent from the following description. [Means for solving the problem]

[0017] 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 opening 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. Equipped with The second air spring applies a force in the opening direction to the exhaust valve rod to accelerate the exhaust valve rod from a position where the exhaust port is closed to a predetermined intermediate position in the opening process to a position where the exhaust port is fully opened, and does not apply a force to the exhaust valve rod after the intermediate position in the opening process. An exhaust valve drive device characterized by: 2. 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. 1. The exhaust valve drive device according to claim 1. 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 opening 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. Equipped with 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, a force in the opening direction is applied to the exhaust valve rod to accelerate the exhaust valve rod, and after the intermediate position in the opening process, no force is applied to 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, no force is applied to the exhaust valve rod, and from the intermediate position in the closing process onwards, a force in the opening direction is applied to the exhaust valve rod to decelerate the exhaust valve rod. An exhaust valve drive device characterized by: 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 intermediate position in the closing process is near the position where the inertial force of the exhaust valve rod changes from the opening direction to the closing direction. 4. The exhaust valve drive device according to claim 3. 5. The first air spring is configured to compress and expand the volume of the sealed space in the first air spring cylinder by a first annular piston attached to the exhaust valve rod, the second air spring is configured to compress and expand the volume of a sealed space in a second air spring cylinder by a second annular piston having a push-up rod attached toward the first annular piston, When the position of the exhaust valve rod is between the position that blocks the exhaust port and the intermediate position, the first annular piston is in contact with the push-up rod, thereby acting a force on the exhaust valve rod, When the position of the exhaust valve rod is between the intermediate position and the position that opens the exhaust port, the second annular piston abuts against the stopper and stops, and the first annular piston moves away from the push-up rod. No force is applied to the exhaust valve rod. 5. The exhaust valve drive device according to any one of the above items 1 to 4. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an exhaust valve drive device for use in an internal combustion engine such as a diesel engine, which has reduced drive power consumption. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of an exhaust valve drive device according to an embodiment of the present invention; [Figure 2] FIG. 1 is a vertical cross-sectional view showing a configuration of an exhaust valve drive device according to an embodiment. [Figure 3] FIG. 1 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of an exhaust valve drive device according to an embodiment. [Figure 4] FIG. 1 is a vertical cross-sectional view showing a schematic configuration (valve open state) of an exhaust valve drive device according to an embodiment. [Figure 5] 1A is a graph showing an exhaust valve acting force pattern and a valve element opening degree in an exhaust valve drive device according to an embodiment; FIG. 1B is a graph showing a pressure change of high-pressure oil for driving and a valve element opening degree in an exhaust valve drive device according to an embodiment; [Figure 6] FIG. 1 is a vertical cross-sectional view showing the configuration of a conventional exhaust valve drive device. [Figure 7]Graph (a) showing the exhaust valve acting force pattern and valve element opening in a conventional exhaust valve drive device, and graph (b) showing the pressure change of the driving high-pressure oil and valve element opening in a conventional exhaust valve drive device. DETAILED DESCRIPTION OF THE INVENTION

[0020] The exhaust valve drive device according to the present invention is used in an internal combustion engine, such as a diesel engine, particularly mounted on a ship.

[0021] Preferred embodiments of the present invention will now be described. FIG. 1 is a block diagram showing a schematic configuration of an exhaust valve drive device according to an embodiment.

[0022] As shown in Figure 1, the exhaust valve drive device of this embodiment 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 rod 3 that is moved 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 rod 3.

[0023] The drive hydraulic pump 8 has a proportional control valve 9, and when an exhaust valve open signal or an exhaust valve close signal is sent to this proportional control valve 9 from the engine control device 11, 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 take in and out high-pressure drive oil. Note that the drive hydraulic pump 8 can be made compact by increasing the pressure P of the drive oil (pressure source), reducing the diameter of the cylinder of the drive hydraulic pump 8, and reducing the pressure of the drive oil to use it as high-pressure drive oil.

[0024] The high-pressure driving oil delivered from the driving hydraulic pump 8 is sent to the housing 10 via a high-pressure pipe 12 to move the actuator 4. The actuator 4, driven by the high-pressure driving oil, operates integrally with the exhaust valve rod 3 and biases it in the opening direction to open the exhaust port of the combustion chamber.

[0025] FIG. 2 is a vertical cross-sectional view showing the configuration of the exhaust valve drive device of the embodiment.

[0026] As shown in Figure 2, this exhaust valve drive device is installed above the exhaust port of the combustion chamber and includes a housing 10 having an exhaust tube 1 that guides exhaust from the exhaust port. An exhaust tube end 1a, which is the end of the exhaust tube 1, is butted against the exhaust port of the combustion chamber. Exhaust gas is exhausted from the combustion chamber from the exhaust port of the combustion chamber and exhaust tube end 1a, as shown by arrow E in Figure 2.

[0027] This exhaust valve drive device includes an exhaust valve rod 3 supported by a housing 10 so as to be movable in the direction toward and away from the exhaust tube end 1a. The exhaust valve rod 3 has a valve body 2 at its tip that opens and closes the exhaust tube end 1a, and is driven by a hydraulic mechanism.

[0028] The valve element 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 element 2 opens the exhaust pipe end 1a by being moved away from the valve seat 1b toward the combustion chamber side.

[0029] The exhaust valve rod 3 has a valve disc 2, which is the tip portion, positioned within the combustion chamber, and a rod-shaped shaft portion 3a continuing from the valve disc 2, which extends through the exhaust stack 1 to the outside of the combustion chamber and is supported by the housing 10. The valve disc 2 is pressed against the valve seat 1b as shown by arrow C in FIG. 2 by the gas pressure inside the combustion chamber, as shown by arrow GP in FIG. 2. The shaft portion 3a of the exhaust valve rod 3 is driven in the direction of entering the combustion chamber (the opening direction shown by arrow O) by the hydraulic pressure of the high-pressure driving oil, as shown by arrow OP in FIG. 2. An actuator 4 is attached to the base end portion of the exhaust valve rod 3, which receives the hydraulic pressure OP of the high-pressure driving oil and moves the exhaust valve rod 3 in the opening direction.

[0030] The movement range of the exhaust valve rod 3 is a range that spans between a position where the valve body 2 closes the exhaust stack end 1a and a position where the exhaust stack end 1a is fully open.

[0031] FIG. 3 is a vertical cross-sectional view showing a schematic configuration (valve closed state) of the exhaust valve drive device of the embodiment. FIG. 4 is a vertical cross-sectional view showing a schematic configuration (valve open state) of the exhaust valve drive device of the embodiment.

[0032] As shown in Figures 2, 3, and 4, the exhaust valve rod 3 is provided with a first air spring 5a and a second air spring 5b. The first air spring 5a is configured to compress and expand the volume of the sealed space in the first air spring cylinder 6 provided around the approximate center of the shaft portion 3a of the exhaust valve rod 3 by a first annular piston 7 attached to the exhaust valve rod 3. Air pressure indicated by arrow P1 in Figures 2, 3, and 4 is supplied into the first air spring cylinder 6, resulting in pressure P1.

[0033] The first air spring 5a has a stroke X1 in which the valve body 2 blocks the exhaust pipe end 1a to the position where the valve body 2 opens (fully opens) the exhaust pipe end 1a. Over the entire range of movement, the first air spring cylinder 6 forms an airtight space, and exerts a force on the exhaust valve rod 3 in the blocking direction (arrow C) away from the combustion chamber, blocking the exhaust pipe end 1a (exhaust port) over the entire range of movement.

[0034] The second air spring 5b is configured to compress and expand the volume of the sealed space inside a second air spring cylinder 13 provided around the shaft portion 3a at a location closer to the actuator 4 than the first air spring 5a, by a second annular piston 14. Air pressure indicated by arrow P2 in Figures 2, 3 and 4 is supplied to the inside of the second air spring cylinder 13, and the pressure becomes P2.

[0035] The second air spring 5b applies a force in the opening direction (arrow O) to open the exhaust cylinder end portion 1a to the exhaust valve rod 3 only in a partial section within the movement range of the exhaust valve rod 3 that spans from the position where the valve body 2 closes the exhaust cylinder end portion 1a to the position where the exhaust cylinder end portion 1a is fully open.

[0036] The second air spring 5b applies a force in the opening direction (arrow O) to open the exhaust cylinder end portion 1a to the exhaust valve rod 3 in a section (<X1) that spans from the position where the valve body 2 closes the exhaust cylinder end portion 1a to an intermediate position where the exhaust cylinder end portion 1a reaches a predetermined opening degree (0% < opening degree < 100%).

[0037] An upward push rod 15 is attached to the second annular piston 14 of the second air spring 5b so as to face the first annular piston 7 of the first air spring 5a. As shown in FIG. 3, the second annular piston 14 of the second air spring 5b compresses the inside of the second air spring cylinder 13 by the lower end of the upward push rod 15 being pushed up by the first annular piston 7 of the first air spring 5a.

[0038] The second air spring 5b applies a force in the opening direction to accelerate the exhaust valve rod 3 with respect to the exhaust valve rod 3 until a predetermined intermediate position in the opening process from the position where the exhaust cylinder end portion 1a is closed to the position where the exhaust cylinder end portion 1a is fully opened, and does not apply a force to the exhaust valve rod 3 after the intermediate position in the opening process.

[0039] The second air spring 5b applies a force in the opening direction (arrow O) to open the exhaust cylinder end portion 1a to the exhaust valve rod 3 because the lower end of the upward push rod 15 is in contact with the first annular piston 7 of the first air spring 5a. This force in the opening direction (arrow O) accelerates the exhaust valve rod 3 when opening the exhaust cylinder end portion 1a and decelerates the exhaust valve rod 3 when closing the exhaust cylinder end portion 1a.

[0040] When the exhaust pipe end 1a is at a predetermined opening angle (0%<opening angle<100%), the second annular piston 14 of the second air spring 5b comes into contact with a stopper 14a in the housing 10 and stops, as shown in FIG. 4, and the second air spring 5b does not expand the inside of the second air spring cylinder 13 any further. At this time, the first annular piston 7 of the first air spring 5a moves away from the lower end of the push rod 15. When the first annular piston 7 of the first air spring 5a moves away from the lower end of the push rod 15, the second air spring 5b no longer applies force to the exhaust valve rod 3 (becomes inactive).

[0041] From the position where the valve body 2 blocks the exhaust pipe end 1a to the intermediate position where the exhaust pipe end 1a becomes a predetermined opening (0% < opening < 100%), the force that the second air spring 5b acts on the exhaust valve rod 3 is a force that does not generate negative pressure in the hydraulic pressure OP of the driving high-pressure oil.

[0042] During the opening process, the intermediate position where the second air spring 5b becomes 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 rod 3 moves in the opening direction changes from negative (closing direction) to positive (opening direction). Furthermore, during the closing process, the intermediate position at which the exhaust pipe end 1a at which the second air spring 5b begins to act reaches a predetermined opening (0% < opening < 100%) is the position or near that position at which the inertial force when the exhaust valve rod 3 moves in the opening direction changes from positive (opening direction) to negative (closing direction).

[0043] In the closing process in which exhaust stack end 1a moves from an open (fully open) position to a closed position, second air spring 5b does not act until an intermediate position, and only first air spring 5a acts.

[0044] In the closing process (Fig. 4 → Fig. 3) leading to the closing of the exhaust pipe end 1a, when the first annular piston 7 of the first air spring 5a comes into contact with the lower end of the push rod 15 and begins to push it up, a deceleration force from the second air spring 5b acts to decelerate the exhaust valve rod 3, reducing the speed at which the valve body 2 seats on the valve seat 1b and achieving a more gradual seating.

[0045] 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, [(gas pressure GP inside the combustion chamber) + (total force of the first air spring 5a and the second air spring 5b) + (inertia force of the exhaust valve rod 3)]. By reducing the total air spring force using the second air spring 5b, the maximum oil pressure (Pomax) can be reduced and the pressure P of the driving oil (pressure source) can be lowered, thereby reducing the driving power consumption.

[0046] When the exhaust pipe end 1a is blocked, the peak value of the oil pressure (Pcmax) can be reduced by an amount equivalent to the force of the second air spring 5b, thereby increasing the durability of equipment such as the piston ring of the actuator 4.

[0047] FIG. 5(a) 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. 5(b) 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 driving device of the embodiment. In Figure 5(a), the opening direction of the exhaust pipe end 1a is shown as positive (+) and the closing direction is shown as negative (-), and the opening degree of the exhaust pipe end 1a (valve body 2) (dashed line), the inertial force of the exhaust valve rod 3 (dashed line), the gas pressure GP inside the combustion chamber acting on the valve body 2 (dashed line), the force of the first air spring 5a (thin line), and the force of the second air spring 5b (thick line) are shown. In FIG. 5(b), the opening direction of the exhaust stack end 1a is indicated by positive (+) and the closing direction is indicated by negative (-), and the pressure of the high-pressure oil for driving (thin line) is shown.

[0048] In this exhaust valve drive device, the exhaust stack end 1a is opened and closed through the following valve operating steps (A) to (G) shown as (A) to (G) in FIGS. 5(a) and 5(b). (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 second air spring 5b acts, and the force required for the valve opening operation (hydraulic pressure OP of the driving high-pressure oil) can be reduced by an amount equivalent to the force of the second air spring 5b, thereby reducing the driving power consumption. (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 becomes inactive, and the valve speed is decelerated. (D) When the exhaust pipe end 1a approaches the open position (fully open), the exhaust valve rod 3 is decelerated by controlling the force of the first air spring 5a and the hydraulic pressure OP of the driving high-pressure oil, and the exhaust pipe end 1a reaches the open position (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 force of the first air spring 5a. At this time, the second air spring 5b is inactive, and the exhaust valve rod 3 is accelerated by the force of the first air spring 5a. (F) As the exhaust pipe end 1a approaches closure and the inertial force of the exhaust valve rod 3 becomes negative (in the closure direction (-)), the second air spring 5b begins to act, decelerating the exhaust valve rod 3. The hydraulic pressure OP of the driving high-pressure oil is controlled up to the peak hydraulic pressure Pcmax at the time of valve closure to further decelerate the exhaust valve rod 3 and suppress the seating speed of the valve body 2. At this time, due to the action of the force of the second air spring 5b, the force required to decelerate the exhaust valve rod 3 (hydraulic pressure OP of the driving high-pressure oil) can be reduced by an amount equivalent to the force of the second air spring 5b, thereby increasing the durability of the equipment (for example, the piston ring of the actuator 4, etc.). (G) The valve disc 2 is gently seated on the valve seat 1b by the sum of the forces of the first air spring 5a and the second air spring 5b and the controlled hydraulic pressure OP of the high-pressure drive oil. Because the forces of the first air spring 5a and the second air spring 5b are in opposite directions, the sum of these forces is the force of the second air spring 5b minus (cancelled out) the force of the first air spring 5a.

[0049] 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), which is 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.

[0050] In this exhaust valve drive device, the maximum pressure (Pomax) of the high-pressure drive oil can be made lower than before by an amount equivalent to the force of the second air spring 5b, 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 Fig. 5, it can be seen that the maximum pressure (Pomax) is reduced to approximately 70% of that of the conventional exhaust valve drive device shown in Fig. 7. Therefore, it can be seen that the exhaust valve drive device according to the present invention can reduce drive power consumption. [Explanation of symbols]

[0051] 1 Exhaust stack 1a Exhaust pipe end 2 Valve body 3 Exhaust valve stem 4 Actuators 5a First air spring 5b Second air spring 6. First air spring cylinder 7 Annular piston 8 Drive hydraulic pump 9 Proportional Control Valve 10. Cabinet 11 Engine control device 12 High-pressure pipe 13 Second air spring cylinder 14 Annular piston 14a Stopper 15 Push-up bar

Claims

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 opening 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. Equipped with The second air spring applies a force in the opening direction to the exhaust valve rod to accelerate the exhaust valve rod from a position where the exhaust port is closed to a predetermined intermediate position in the opening process to a position where the exhaust port is fully opened, and does not apply a force to the exhaust valve rod after the intermediate position in the opening process. An exhaust valve drive device characterized by:

2. 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.

2. The exhaust valve drive device according to claim 1.

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 opening 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. Equipped with 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, a force in the opening direction is applied to the exhaust valve rod to accelerate the exhaust valve rod, and after the intermediate position in the opening process, no force is applied to 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, no force is applied to the exhaust valve rod, and from the intermediate position in the closing process onwards, a force in the opening direction is applied to the exhaust valve rod to decelerate the exhaust valve rod. An exhaust valve drive device characterized by:

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 intermediate position in the closing process is near the position where the inertial force of the exhaust valve rod changes from the opening direction to the closing direction.

4. The exhaust valve drive device according to claim 3.

5. The first air spring is configured to compress and expand the volume of the sealed space in the first air spring cylinder by a first annular piston attached to the exhaust valve rod, the second air spring is configured to compress and expand the volume of a sealed space in a second air spring cylinder by a second annular piston having a push-up rod attached toward the first annular piston, When the position of the exhaust valve rod is between the position that blocks the exhaust port and the intermediate position, the first annular piston is in contact with the push-up rod, thereby acting a force on the exhaust valve rod, When the position of the exhaust valve rod is between the intermediate position and the position that opens the exhaust port, the second annular piston abuts against the stopper and stops, and the first annular piston moves away from the push-up rod, so that no force is applied to the exhaust valve rod.

5. The exhaust valve drive device according to claim 1, wherein the exhaust valve drive device is a drive device for a vehicle.

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