JP5926372B2 - Multi cylinder piston engine - Google Patents

Description

  The present invention relates to a multi-cylinder piston engine according to the first stage of claim 1. The engine has at least one cam operated valve lift device for each starter and each cylinder of the engine, and the valve lift device is configured to open a gas exchange valve.

  Large internal combustion engines used as primary or auxiliary engines to create electricity and / or heat at ships or power plants typically use compressed air that is continuously injected into the engine's cylinders to rotate the crankshaft It is started by doing. It is desirable to minimize the consumption of start-up air in order to save the energy and space required to store the start-up air and therefore precise control of air injection is required.

  Patent document 1 discloses a starting system for a multi-cylinder piston engine. A pipe system connects a pressure medium source to each cylinder of the engine. Each cylinder is provided with a starting air valve for introducing a pressure medium into the cylinder. Each start valve is controlled by a control valve. The starting system includes a timing device having a control component that is mechanically connected to the rotating components of the engine. This type of starter guarantees the exact timing of the start air injection, but the disadvantage is that the control air must be delivered to each control valve by a separate control air pipe. Also, different timing devices need to be designed for engines with different numbers of cylinders.

WO2007 / 003693 A1

  It is an object of the present invention to provide a multi-cylinder piston engine with an improved starter. The engine according to the invention is characterized by the features of claim 1.

  In accordance with the present invention, a multi-cylinder piston engine has at least one cam operated valve lift device for each cylinder of the engine, and the valve lift device is configured to open a gas exchange valve. The starter includes a pressure medium source, at least one start valve for introducing the pressure medium into the engine cylinder, means for connecting the pressure medium source to the start valve, and a start valve for each cylinder of the engine comprising the start valve. A control valve for controlling the operation of Each control valve is configured to be operated by a gas exchange cam of the respective cylinder.

  The present invention has several advantages. Since the start valve is controlled by a gas exchange cam, a separate start cam is not required. The same cam can be used regardless of the number of cylinders in the engine, and there is no need to design different starting cams for engines with different numbers of cylinders. The start-up air can be distributed to the cylinders with one start-up air duct instead of a separate duct for each cylinder. This saves both space and material. The present invention also allows reliable and accurate control of start-up air injection.

  According to the embodiment of the present invention, each gas exchange cam for operating the control valve has a portion arranged below the basic circle of the cam for operating the control valve. A simple and reliable control mechanism can be realized when the control valve is operated by the part of the gas exchange cam under the base circle of the gas exchange cam. The same cam can be used for engines with different numbers of cylinders and no separate adjustment for start air timing is required.

  According to an embodiment of the present invention, each control valve is in flow communication with the pressure medium source and the respective start valve via a control air duct.

  In accordance with an embodiment of the present invention, the control valve causes the pressure medium to enter the start valve to open the start valve when the valve lift device engages a portion of the gas exchange cam that is below the base circle of the gas exchange cam. Configured to allow flow.

  According to an embodiment of the present invention, each control valve has a valve member that can be moved by a valve lift device.

  According to an embodiment of the present invention, the valve lift device includes a plunger that pushes the valve member toward the gas exchange cam when the valve lift device engages a portion of the gas exchange cam that is below the base circle of the gas exchange cam. Have

  According to an embodiment of the present invention, the valve member is pushed toward the valve lift device by the pressure of the pressure medium.

  According to an embodiment of the present invention, the gas exchange cam is an intake cam. Start-up air injection starts near top dead center and ends near the crank angle at which the exhaust valve opens. When the intake cam is used to control the starting valve, the portion of the cam below the base circle is far from the cam protrusion. The shape of the part below the base circle is therefore not determined by the shape of the protrusion. If the portion below the base circle is near the cam protrusion, there may be some restrictions on the shape of the portion below the base circle.

  According to an embodiment of the present invention, each intake cam has a second portion located below the cam base circle to control the operation of the variable intake valve closure, and from the cam base circle. The part arranged below is also arranged below this second part.

  According to an embodiment of the present invention, the gas exchange cam is an exhaust cam. When the control valve is operated by an exhaust cam, the present invention can also be used in a two-stroke engine having a cam operated exhaust valve.

  According to an embodiment of the present invention, in a two-stroke engine, at least three cylinders of the engine are provided with start valves, and in a four-stroke engine, at least five cylinders of the engine are provided with start valves.

  According to an embodiment of the invention, all cylinders of the engine are provided with start valves. Since the same cam profile and valve lift device can be used for all cylinders of the engine, it is practical to provide start valves for all cylinders.

  According to an embodiment of the present invention, each control valve includes an intake passage for introducing pressure medium into the control valve, a discharge passage for introducing pressure medium into the start valve to open the start valve, and a control valve. A drain passage for discharging the pressure medium out of the control valve when not actuated by the gas exchange cam;

  According to an embodiment of the invention, the starter has a main start valve for starting the engine.

FIG. 1 schematically shows a starting system for an internal combustion engine. FIG. 2 shows a simplified cross-sectional view of a portion of a cylinder head having a gas exchange valve and a start valve. FIG. 3 shows an engine intake cam and start valve control apparatus at different stages of operation according to an embodiment of the present invention. FIG. 4 shows an engine intake cam and start valve control apparatus at different stages of operation according to an embodiment of the present invention. FIG. 5 shows an engine intake cam and start valve control apparatus at different stages of operation according to an embodiment of the present invention. FIG. 6 shows an engine intake cam and start valve control apparatus at different stages of operation according to an embodiment of the present invention. FIG. 7 shows a control device for an intake cam and a start valve of an engine according to another embodiment of the present invention. FIG. 8 schematically shows a starting system for an internal combustion engine according to another embodiment of the present invention. FIG. 9 shows a control device for an engine exhaust cam and an air injection valve. FIG. 10 shows the vertical position of the cam follower at different crank angles. FIG. 11 shows the vertical position of the cam follower at different crank angles for an engine with a VIC.

  Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings.

  FIG. 1 schematically shows a starting device for a piston engine 20. In the example of FIG. 1, the engine 20 has six cylinders 19, but the engine 20 may have any reasonable number of cylinders 19 arranged, for example, in series or in a V shape. The engine 20 is a large internal combustion engine, such as used to generate electrical power and / or heat at a power plant or as a ship's main or auxiliary engine. In the embodiment shown in FIG. 1, all cylinders 19 are provided with means for introducing a pressure medium, such as compressed air, into the cylinders 19 in order to start the engine 20. However, in an engine with many cylinders, not all cylinders of the engine need be used for starting. In the case of a 4-stroke engine, start-up air injection into at least 5 of the cylinders is required to allow the engine to start regardless of the initial crankshaft position. In a two-stroke engine, three cylinders are sufficient. If the engine is equipped with means for rotating the crankshaft to a better starting position, a cylinder with a smaller number of starting air injections is sufficient. However, the starting device according to the present invention allows the use of the same means for injecting starting air into each cylinder 19 of the engine 20, so that all cylinders 19 of the engine 20 can be used for starting. It is practical.

  The compressed air is stored in the starting air tank 18. From this starting air tank 18, compressed air can be introduced into the cylinder 19 of the engine 20 via a starting air duct 26. Instead of air, other pressurized gases can also be used. The starting air tank 18 may be filled with a compressor (not shown). Each cylinder 19 of the engine 20 used for starting is provided with a starting valve 10. In FIG. 2, the start valve 10 is shown in relation to the cylinder head 23. The cylinder head 23 is also provided with an intake duct 32 for introducing combustion air into each cylinder 19 and an exhaust duct 33 for guiding exhaust gas out of the cylinder 19. One or more intake valves 24 and one or more exhaust valves 25 are arranged in the cylinder head 23 to open and close the connection between the cylinder 19 and the intake and exhaust ducts 32, 33. The operation of each start valve 10 is controlled by a respective control valve 12. Each cylinder 19 of the engine 20 can also include more than one start valve 10. If each cylinder 19 comprises, for example, two start valves 10, both valves 10 can be controlled by the same control valve 12. The control valve 12 is connected to the start air duct 26. The start air duct 26 includes a main start valve 17 for controlling when the engine 20 is started. Examples of start valve 10 and control valve 12 are shown in the simplified diagrams of FIGS. 3-6.

  According to the embodiment of the present invention, the starting device has a valve lift device 4 and a gas exchange cam 1. The gas exchange cam 1 is shown rotated 90 degrees around the vertical axis to better show the cam profile 2. The cam profile 2 of the gas exchange cam 1 has a base circle 2a, a projecting portion 2b, and a portion 2c arranged below the base circle 2a. The expression “below the base circle” means that the radius of that part of the cam profile 2 is smaller than the radius of the base circle 2a. The radius of the portion 2c below the base circle 2a need not be constant over the entire portion 2c. In the embodiment shown in FIGS. 3-6, the gas exchange cam 1 is an intake cam, and the valve lift device 4 is configured to open the intake valve 24 of the engine 20. The same cam lift device 4 can be used to open the exhaust valve 25 of the engine 20.

  The cam lift device 4 includes a body portion 5 and a reciprocating plunger 6 disposed inside the body portion 5. The plunger 6 is arranged to lift the push rod 8. The cam follower 3 is attached to the plunger 6 using a bearing. A coil spring 7 between the body portion 5 and the plunger 6 presses the cam follower 3 against the cam profile 2. The lifting device moves in a conventional manner. When the cam follower 3 is in the portion 2c of the cam profile 2 below the base circle 2c, the plunger 6 is in the lowest position. The body portion 5 includes a stopper surface 9 so that the positions of the push rod 8 and the intake valve 24 do not change when the cam follower 3 leaves the base circle 2a and enters the portion 2c below the base circle 2a, or vice versa. The push rod 8 can be supported against the stopper surface 9. When the intake cam 1 rotates, the cam follower 3 comes to engage with the protruding portion 2b of the cam profile 2 later. The plunger 6 and the push rod 8 are moved upward, and the intake valve 24 is opened. FIG. 4 shows a state in which the intake valve 24 is fully opened.

  Each cylinder 19 of the engine 20 includes a start valve 10 having a valve member 22. The starting valve 10 is kept closed by a spring 11. In order to control the operation of the start valve 10, each valve lift device 4 includes a control valve 12. When the cam follower 3 engages with the portion 2c of the cam profile 2 below the base circle 2a, the plunger 6 pushes the valve member 13 in the control valve 12 downward, as shown in FIG.

  In order to start the engine 20, the main start valve 17 is opened. This allows start air to enter the start air duct 26 and flow to the control valve 12. The compressed air enters the control valve 12 via the suction passage 14. In these control valves 12 in which the cam follower 3 is connected to the valve lift device 4 in the basic circle 2a or the protrusion 2b of the intake cam 1, the compressed air is shown in FIG. 4 above the valve member 13 in the control valve 12. Push to position. The valve member 13 thus allows compressed air to flow out of the control valve 12 through the drain passage 16. Air is discharged from the drain passage 16 to, for example, the engine room. In contrast, in these control valves 12 in which the cam follower 3 is connected to the valve lift device 4 in the portion 2c below the basic circle 2a of the intake cam 1, the plunger 6 is a valve member as shown in FIG. Press 13 down. This closes the connection between the suction passage 14 and the drain passage 16 and the starting air flows to the starting valve 10. Air is introduced into the space above the valve member 22 of the start valve 10 through the control air inlet 27 and the air pressure pushes the valve member 22 downward and opens the start valve 10. The start air therefore enters the start air duct 26 from the start air tank 18 to the start valve 10 and through the start air inlet 28 to the cylinder 19 of the engine 20, pushing the piston down and rotating the crankshaft of the engine 20. .

  When the camshaft further rotates, the cam follower 3 leaves the portion 2c below the basic circle 2a of the cam profile 2 of the intake cam 1 and enters the basic circle 2a again. The pressure in the suction passage 14 and the pressure created by the valve member 22 of the start valve 10 when pushed upward by the spring 11 will therefore push the valve member 13 upward in the control valve 12. As a result, the connection between the suction passage 14 and the drain passage 16 of the control valve 12 is reopened as seen in FIG. 6, and the start-up air injection into the respective cylinders 19 is terminated. The starting air is continuously (in order) injected into the cylinder 19 of the engine 20 until the engine 20 is started. When the engine 20 starts, the main start valve 17 can be closed.

  These cam lift devices 4 used to open the exhaust valve 25 with different cam profiles 2 in which the part 2c below the base circle 2a is in different positions can also be used to control the start valve. However, since the part 2c below the base circle 2a can be arranged away from the protrusion 2b of the cam profile 2, it is advantageous to use an intake cam for this purpose. This ensures a smooth operation of the cam lift device 4 and the control valve 12.

  FIG. 7 shows a slightly different embodiment of the present invention. In this embodiment, the push rod 8 is moved by a piston 30 located between the push rod 8 and the plunger 6. A second spring 29 for removing the gap between the push rod 8 and the plunger 6 is disposed between the piston 30 and the plunger 6. A gap 31 is formed between the plunger 6 and the piston 30 when the cam follower 3 engages a portion 2c of the cam profile 2 that is below the base circle 2a of the cam profile 2. The second spring 29 holds the piston 30 against the end of the push rod 8 so that no gap is formed between the push rod 8 and the piston 30 or between the upper end of the push rod 8 and the rocker arm. This ensures a smooth operation of the valve lift device 4.

  FIG. 10 shows a graph of the position of the cam follower 3. The broken line indicates the position of the cam follower of the exhaust valve 25, and the solid line indicates the position of the cam follower of the intake valve 24. The plunger 6 follows the same curve. The push rod 8 and the valve lift can also be shown that the vertical position of the push rod 8 cannot be negative due to the stopper surface 9 in the embodiment of FIGS. 3-6 or the piston / spring configuration 29, 30 of the embodiment of FIG. Except for the same curve. The region below the horizontal axis shows how the cam follower 3 of the intake valve lift device 4 engages with the portion 2c below the base circle 2a. Start-up air injection occurs during this phase, and in the illustrated embodiment starts at a top dead center (TDC) line during the compression process, and a crank angle of about 90 degrees after top dead center during the power process. It continues until.

  FIG. 11 shows the vertical position of an engine cam follower with a variable intake valve closure (VIC). In this embodiment, the intake cam profile has a portion disposed below the base circle to control intake valve closing timing. The other part for controlling the start valve is arranged below the part for controlling the intake valve closing timing.

  FIG. 8 shows another embodiment of the present invention, where the start air duct 26 and the start air tank 18 are also used to introduce additional combustion air into the cylinder 19 of the engine 20. The term “additional combustion air” here refers to the air that is introduced into the cylinder 19 of the engine 20 before ignition but after normal intake has ended. In a four-stroke engine, this means that additional combustion air is introduced into the cylinder after the intake valve of the cylinder 19 is closed. Additional combustion air can be introduced into the cylinder 19 of the engine 20 to reduce turbo lag in situations where the engine load suddenly increases. In the embodiment of FIG. 8, the engine 20 includes a control air duct 21 that connects the control valve 12 to the starting air tank 18. The main start valve 17 is arranged in the control air duct 21. The starting air duct 26 is provided with a closing valve 34. Each cylinder 19 of the engine 20 includes a second control valve 12 ′ for controlling the injection of additional combustion air into the cylinder 19. The second control valve 12 'is connected to the starting air tank 18 using a second control air duct 21'. The second control air duct 21 'comprises an air injection control valve 17' for controlling when the injection of additional combustion air is turned on. In the embodiment of FIG. 8, the start valve 10 is also used to introduce additional combustion air into the cylinder 19. However, a separate valve can also be used. The control air duct 21 includes a check valve 32 downstream from each control valve 12 to prevent additional combustion air from leaking through the respective control valve 12 when additional combustion air is introduced into the engine 20. Similarly, the second control air duct 21 ′ provides a second check downstream from each control valve 12 ′ to prevent start-up air from leaking through the second control valve 12 ′ during engine 20 startup. A valve 32 'is provided.

  The second control valve 12 'is operated by the exhaust cam 1' of the engine 20, as shown in FIG. The valve lift device 4 used to open the exhaust valve 25 may be the same as the valve lift device 4 used to open the intake valve 24. The cam profile 2 ′ of the exhaust cam 1 ′ is different from the cam profile 2 of the intake cam 1, but otherwise the second control valve 12 ′ is operated in the same way as the first control valve 12. In the exhaust cam 1 ′, the portion 2c ′ below the base circle 2 ′ can be arranged away from the protrusion 2b ′ of the cam profile 2 ′, so that the exhaust cam 1 ′ can be operated to operate the second control valve 12 ′. It is advantageous to use However, it is also possible to use the intake cam 1 to operate the second control valve 12 ′ and to use the exhaust cam 1 ′ to operate the first control valve 12. The second control valve 12 'is the same as the first control valve 12, and includes a valve member 13', a suction passage 14 ', a discharge passage 15', and a drain passage 14 '.

  It will be appreciated by persons skilled in the art that the present invention is not limited to the embodiments described above, but may vary within the scope of the appended claims.

Claims (14)

Having at least one cam operated valve lift device for each cylinder of a multi-cylinder piston engine, wherein the valve lift device is configured to open a gas exchange valve;
The engine further includes:
-Pressure medium source,
At least one start valve for introducing a pressure medium into the cylinder of the engine;
-Means for connecting the source of pressure medium to the start valve; and-a control valve for each cylinder comprising the start valve to control the operation of the start valve;
A multi-cylinder piston engine having a starter,
Each of the control valves is configured to be operated by a gas exchange cam of the respective cylinder.
engine. Each of the gas exchange cams for operating the control valve has a portion disposed below a basic circle of the cam for operating the control valve.
The engine according to claim 1. Each control valve is in flow communication with the pressure medium source and the respective start valve via a control air duct,
The engine according to claim 1 or 2. Each of the control valves has a pressure medium that opens the start valve when the valve lift device engages the portion of the gas exchange cam below the base circle of the gas exchange cam. Configured to allow to flow into,
The engine according to claim 3. Each of the control valves has a valve member that is movable by the valve lift device.
The engine according to claim 4. The valve lift device includes a plunger that pushes the valve member toward the gas exchange cam when the valve lift device engages with the portion of the gas exchange cam below the base circle of the gas exchange cam. Have
The engine according to claim 5. The valve member is pushed toward the valve lift device by the pressure of the pressure medium.
The engine according to claim 5 or 6. The gas exchange cam is the intake cam;
The engine according to any one of claims 1 to 7. Each of the intake cams has a second portion disposed below the base circle of the cam and is disposed below the base circle of the cam to control variable intake valve closing operation. The portion is also disposed below the second portion,
The engine according to claim 8. The gas exchange cam is the exhaust cam;
The engine according to any one of claims 1 to 7. In a two-stroke engine, at least three of the cylinders of the engine include the start valve, and in a four-stroke engine, at least five of the cylinders of the engine include the start valve.
The engine according to any one of claims 1 to 10. All the cylinders of the engine are provided with the starting valve,
The engine according to claim 11. Each of the control valves includes a suction passage for introducing the pressure medium into the control valve, a discharge passage for introducing the pressure medium into the start valve to open the start valve, and the control valve includes the gas A drain passage for discharging the pressure medium out of the control valve when not actuated by an exchange cam;
The engine according to any one of claims 1 to 12. The starter has a main start valve for starting the engine.
The engine according to any one of claims 1 to 13.

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