DK172961B1 - Hydraulic central unit for a cylinder in an internal combustion engine - Google Patents

Description

in DK 172961 B1

The invention relates to a hydraulic central unit for a cylinder in an internal combustion engine, which engine has several fuel pumps and several exhaust valves, wherein at least the exhaust valves are actuated by hydraulic drive devices by means of pressurized hydraulic fluid.

For many years, there have been separate proposals that the fuel pumps and exhaust valves of a large two-stroke cross-head motor should be hydraulically activated instead of the very well-known kamakel actuation. The applicant's Danish patent No. 41046 of 1929 proposed a hydraulically operated fuel pump, and from recent times Danish patent no.

151145 on a hydraulically operated fuel pump and Danish Patent No. 148,664 on an electronically controlled and hydraulically actuated exhaust valve.

The various known proposals for purely hydraulic actuation of exhaust valves and fuel pumps on large two-stroke cross-head motors have not found simultaneous commercial use due, among other things, to the complicated design of the hydraulic feed and control systems with associated high risk of failure in a component causes the engine to stop. A further increased risk over the traditional mechanical systems stems from the well-known fact that hydraulic systems are very sensitive to irregularities in assembly and that faults caused by such irregularities may appear after extended operation as seemingly random failures. .

The invention has for its object to provide the engine with great security against accidental shutdown due to failure of the hydraulic system and to simplify the installation and maintenance of the hydraulic system.

To this end, the hydraulic central unit 35 according to the invention is characterized in that the central unit DK 172961 B1 2 has a block-shaped body comprising at least one port for connecting at least one pressure line for the exhaust valve actuator and control valves for controlling the at least the exhaust valve as well as the interior. ducts connecting the gates to the ports with connections for a high pressure line for supplying the pressurized hydraulic fluid or a drain or low pressure line for relieving the hydraulic pressure, and the central unit having a main switch valve which in an open position is inactive and in a closed position. at least disconnects the high-pressure line from the control unit control valves.

Central unit means a cylinder unit which is central to at least one engine cylinder, but not to the engine as a whole.

In safety, several advantages are obtained by assembling all the central parts of the hydraulic system of the cylinder into a central unit with the most sensitive parts in a block-shaped body, in which the flow passages to and from the various valves and the branching of the connection 20 between the high pressure line and the various valves and consumables can are designed as drilled channels that intersect as needed. The hydraulic central unit can be manufactured in a specialized workshop, where special consideration has been given to the high cleanliness requirements 25 for hydraulic systems, and then the central unit can be delivered together or separated in a few main parts to the workshop, where the central unit is mounted on the engine cylinder. Thus, when mounting on the engine cylinder, no control valves or many small wiring connections must be inserted to connect the control valves to the supply lines and hydraulic consumers.

It is essential for the invention that the central unit comprises a main switch valve for the high pressure supply, which enables individual disconnection of central units. Thus, it is possible to disconnect a central unit on a single cylinder for inspection and possible replacement of a defective part, and to allow the engine to continue at slightly reduced load due to the temporarily switched off cylinder. The central units contain all the parts that have a real risk of breakage. Since the parts for each cylinder are assembled in a standardized central unit, which is found in several identical units on the engine, it is easy for, for example, a ship to have an extra unit in stock for full or partial replacement with any defective hydraulic central unit on the engine. .

The modular design of the hydraulic system components in central units provides great flexibility 15 in designing the engine, which is a particular advantage of large two-stroke cross-head motors, which are usually built one at a time with individual adjustment of cylinder number and cylinder performance to the specific order, because the number of central units is simply 20 can be adjusted to the currently selected number of cylinders.

The ability to cut off the high-pressure line in operation from one of the central units allows separation of a faulty unit and continued operation of the other units. In order to facilitate the separation of the faulty unit and reduce the risk of damage due to hot hydraulic oil discharge, it is preferred that the main switch valve in its closed position connects a drain line with the inner main duct which in the open position of the main switch valve is connected to the high-pressure wiring, forcing a forced discharge of the central unit's high-pressure system immediately after disconnecting the unit.

In a preferred embodiment, the central unit comprises a bracket "mounted on a top plate of a cylinder portion from which the cylinder liner protrudes, and the block-shaped body is mounted on the top of the bracket having such height that The division of the central unit into a block-shaped body and a supporting bracket provides an additional opportunity for simplification of the central unit's manufacture because central units for several different cylinder sizes or several different operating outlets of the same cylinder size can be manufactured with the same block. -10 shaped body and different sizes of the console.

It is extremely easy to mount the bracket to the top plate of the cylinder part, which otherwise carries the cylinder liner. The height of the bracket, which raises the upper surface of the block-shaped body at least 80 cm above the top plate, means that the block-shaped body with the ports for the exhaust valve connections as well as the various valves is at such a height above the aisle platform mounted above the top plate that the working position of the operating personnel when working with the central unit as far as possible is optimal for a standing person. Furthermore, the console causes the upper surface of the block-shaped body to be in the vicinity of the cylinder cover, which results in advantageously short hydraulic connections between the central unit and the exhaust valve actuator, so that the energy consumption for pressurizing the amount of liquid in the high-pressure connection to the actuator is minimized.

It is preferred that there is one central unit per cylinder as this provides the simplest design and maximum design freedom while disabling a central unit affects only the one cylinder associated with the unit.

It is possible to connect the high-pressure line directly to the block-shaped body where the supply of high-pressure hydraulic fluid is to be used in valves, but it is preferred that each central unit contains a section DK 172961 B1 5 of the high-pressure line located in the supporting bracket under the block-shaped body. , and that the main switch valve is in the flow path between this section and the block-shaped body. There is in the central unit a natural interface between the console and the block-shaped body, and by placing the main switch valve under this interface and together with a section of the high-pressure line integrated in the central unit, the connection to the high-pressure line can be severed away from the block-shaped body, so that this can be easily dismantled without affecting the hydraulic supply to the other central units. Thus, the disconnection of a central unit and replacement of the block-shaped body can occur completely without operating disturbances on the other cylinders. By integrating a piece of the high-pressure line into the central unit, the hydraulic system can easily be expanded to larger cylinder numbers by means of standard pipe pieces with a length corresponding to the distance between two neighboring central units and a number of central units.

20 It is possible to supply the engine with fuel via a common high-pressure line, which is continuously supplied with fuel at the injection pressure, but it is preferred that the fuel of the cylinder is supplied by a piston-type hydraulic fuel pump whose 25 hydraulic drives are connected to at least one port. the block-shaped body for connection to the high-pressure line and the low-pressure line or drain line, and the control valve on the block-shaped body controls the fuel delivery from the piston pump independently of the exhaust valve actuator control valve. The hydraulically driven main components of the cylinder are thus assembled on the block-shaped body and are located at a short distance from the cylinder cover in which the injectors and the exhaust valve are mounted so that the hydraulic lines are short in length.

In a further development of this embodiment, the DK 172961 B1 6 fuel pump and associated hydraulic drive are mounted on the upper side of the central unit's block-shaped body. By using the block-shaped body as the basis of the fuel pump, a very simple design is obtained, where the hydraulic pump drive is located directly on the port of the block-shaped body and separate foundations for the fuel pump are omitted. The reduction in the number of components reduces the risk of failure and the fuel pump may also be mounted on the central unit 10 before being delivered to the engine assembly workshop.

In a preferred embodiment, the control valves of the central unit are electronically controlled by a motor control unit and / or a cylinder control unit. The electronic control provides a particularly advantageous opportunity for free control of the fuel pumps and exhaust valves during the motor cycle, ie. the timing of the injection and of the valve opening and closing can be adjusted continuously while the engine is running.

For the purpose of avoiding air penetration into the 20 hydraulic systems, the hydraulic central unit may be connected to the low pressure line supplying hydraulic fluid at a low pressure, preferably less than 4 bar. This supply may be connected to the drain or low pressure ports on the control valves of the exhaust valve actuator 25 and the fuel pump drive, possibly. via a flow limiter, so that the pressure relief maintains an excess pressure which prevents atmospheric air from entering the hydraulic systems. As an alternative to the use of a low pressure conduit in addition to a drain conduit 30, the hydraulic fluid can be discharged to the drain conduit and, if desired, hydraulic fluid can be provided at a suitable low pressure by branching liquid from the high pressure conduit and passing it through a throttle reducing the fluid pressure to the appropriate level. , for example, from 0.5 to 3 bar.

35 The hydraulic central units are completely independent of each other and are all supplied with hydraulic fluid from the high pressure line. It is desirable that a central unit's consumption of hydraulic fluid does not affect the other central units, and it is therefore preferred that the central unit has at least two high-pressure fluid accumulators connected to the high-pressure channels on the side of the high-pressure line of the main switch valve. By placing at least two fluid accumulators on the consumption side of the main switch valve, the central unit becomes self-sufficient with hydraulic fluid at the moment of consumption, which offsets larger pressure fluctuations in the high-pressure line.

On the supply side of the central units, the hydraulic system can be designed such that the central units 15 contain sections of the high-pressure line interconnected by means of two concentric high-pressure pipes mounted between the central units, the two concentric high-pressure pipes being an inner tube which is pressure-sealing at both ends. inserted into a fixed-voltage socket on the side surface of the central unit, and an outer tube carrying at each end a cup-shaped sleeve slidable on the outer tube in this longitudinal direction and mountable on the side surface of the central unit and having a cup bore with a larger diameter than the outer diameter of 25 the bushing on the inner tube. The concentric high-pressure pipes can both withstand the maximum hydraulic pressure, providing high safety against failure. In normal operation, the hydraulic fluid flows only through the inner tube, and in the annulus between the two tubes there may be leakage monitoring which gives an alarm signal of breakage of the inner tube if leakage flow is detected in the gap. Operation of the engine can continue until repair is carried out, with the pressure being carried by the outer tube.

The embodiment offers the advantage that the twin-tube central 35 units are easy to mount on the engine cylinders, even though there are some distance variations in the width of the motor cylinders. After the central units are mounted on the motor cylinders with fairly coarse tolerances, the distance variations can be compensated as follows. Before placing the pipes between two central units, the two bushings on the outer pipe are pushed towards each other so that the bushes on the inner pipe are exposed. Then the flanges are mounted on the inner tube on each central unit. At least one of these flanges 10 may be displaceable and to some extent pivotable on the inner tube, so as to compensate for mounting bias and length variations between the central units.

Then, the cup-shaped bushes can be pushed over the bushes on the inner tube and fixed to each IB central unit.

An example of a preferred embodiment of the invention will now be described in more detail with reference to the drawing, in which: FIG. 1 shows a simplified diagram of a hydraulic system on a two-stroke cross-head motor; FIG. 2 is a schematic diagram of the hydraulic system of a hydraulic central unit according to the invention; FIG. 3 is a side view of the engine of FIG. 1, FIG. 4 shows on a larger scale a section showing the central unit; and FIG. 5 in side view and cut a double tube between two central units.

A hydraulic system supplies hydraulic fluid under pressure to hydraulic drives on cylinders 1 of a multi-cylinder, two-stroke, cross-head motor 2. The hydraulic fluid can be delivered from a storage tank and may be, for example, a standard hydraulic oil, but it is preferred that the engine lubricating oil be used as a hydraulic fluid. the system is fed from the engine oil sump 3. A pre-pump 4 35 sends the hydraulic fluid through at least one filtration device 5 to a low pressure line 6. For example, the pump can maintain a pressure in the low pressure line of between 1 and 5 bar overpressure, typically about 2 bar overpressure. . A pump station 7 comprises a plurality of high-pressure pumps, which can, for example, deliver the hydraulic fluid to a high-pressure line 8 at a pressure located in the range 125-325 bar. Delivery pressure may be adjustable depending on engine load. Some of the high-pressure pumps may be driven by a shaft on the combustion engine, such as the crankshaft, and one or more of the high-pressure pumps may be driven by an electric motor.

The cross-head motor may, for example, be a propulsion engine in a ship or a stationary drive unit in a power plant. The engine has no traditional camshaft, 15 and its exhaust valves 9 and fuel pumps 10 are hydraulically driven and electronically controlled. It is also possible to use a common high-pressure source for constant-pressure fuel, and then omit separate fuel pumps for the individual cylinders, but the hydraulically operated fuel pumps are preferred.

The high-pressure line 8 from the pump station is mounted on the side of a hydraulic central unit 11 adjacent to a section 12 of the high-pressure line which is pre-mounted and integrated into the lower part of the central unit in a bracket 13 which carries on its upper side a block-shaped body 14. From the body 14 For example, a pressure line 15 exits the exhaust valve actuator 16, and a drain line 17 from the actuator returns to the body 14. The body 14 can further connect a hydraulic drive for the fuel pump 10 with either the high pressure line or a return line. The fuel pump delivers fuel to several injectors via pressure pipe 18.

Each cylinder of the motor is associated with an electronic control unit 19 which receives overall synchronization and control signals through lines 20 and DK 172961 B1 10 provides control signals for control valves on the body 14 through lines 21.

A low pressure line 22 is branched from the low pressure line upstream of the pump station 7 and carries low pressure hydraulic fluid such as less than 4 bar and typically about 2 bar overpressure to the central units 11.

A drain line 23 is connected to the central unit for draining used hydraulic fluid to a common drain, for example the motor's motor stand, which is connected to oil sump 3.

In FIG. 2 is an example of the main connections in the central unit 11. From the section 12 of the high-pressure line, a common supply line 25 is branched, which leads up 15 to branches to the consumption points in the block-shaped body 14, which is on the diagram above the dotted line. In normal operation, a main switch valve 24 is in the open position shown, where the high-pressure line is connected to the body 14. When part of the hydraulic system 20 of the cylinder is desired to be separated for inspection, replacement or repair, the valve 24 can be set in the other outer position by manual or electronic operation, whereby the feed line 25 is cut from section 12 of the high-pressure line and connected to the drain line 23 via the branch line 23 ', whereby the entire high-pressure system in the central unit is pressure-relieved so that separation can be effected with minimal waste of hydraulic fluid.

The pre-mounted section 26 of the low pressure line 30 of the central unit is connected to the block-shaped body through a branch line 27. A restriction 28 in conduit 27 limits the inlet pressure of the body 1 to about 1.5 bar overpressure. In the block-shaped body, the branch line is connected via channels 27 ', 27' 'and 27' '' to 35 inlet ports in a control valve 29 for pump 17 and a control valve 30 as well as a main valve 31 for the valve actuator, respectively. Furthermore, the supply line is connected via channels 25 ', 25' 'and 25' '' in the body 11 to access ports in the control valve 29, the control valve 30 and the main valve 31, respectively.

The control valve 30 is electronically activated and has three ports and two positions. It may, for example, be of the magnetic locking type in the outer positions where the valve is actuated by magnetizing one of two coils 10 located at each end of a valve slider of ferro-magnetic material. As safety in the event of failure in the magnetization of the two coils, a spring 32 can preload the valve slider to take the position shown in the figure, where the low pressure line is the active inlet port. Alternatively, the control valve may be a conventional solenoid valve. The outlet port of the control valve 30 is connected to an intermediate channel 33 which communicates the pressure to a piston surface on one end of the slide of the main valve 31, the other end of which has a piston surface with a smaller area which is permanently connected to the high pressure line. When the control valve 30 is in the position shown, the high pressure on the smaller piston area pushes the main slider to the position shown, where the low pressure line is connected via the channel 27 '' '25 to the outlet port of the main valve which leads through a channel 34 to a gate for the pressure line 15 to the exhaust valve actuator. . When the control valve 30 is actuated to its second position with the intermediate channel connected to the feed line 25, the high pressure on the larger piston surface presses the main valve slider to its second position, where the high pressure in the channel 25 '' 'is directed to the pressure line 15, so that the actuator opens the exhaust valve.

The control valve 29 is electronically actuated and can, as shown in the figure, connect the high pressure in the duct 25 'to its outlet port, which leads through a duct 35 to a port in communication with the pressure chamber in the pump drive. In one intermediate position, the valve inlet ports are disconnected from its outlet port, and in another outer position, the valve outlet port is connected to the low pressure conduit 27 'which contains a restriction 36 which further limits the pressure to, for example, 0.5 bar overpressure. Thus, the control valve has three gates and three positions and can have a 10 fast-acting pilot glider which, by hydraulic actuation, sets a main glider. The pilot slider and / or main slider is provided with a position sensor that delivers a signal on the valve setting to the associated control unit 19. For example, the control valve may be of the type described in applicant's WO 94/29578.

Immediately after the main switch valve 24, a high pressure fluid accumulator 37 is connected to the feed line 25. The accumulator is made up of a pressure vessel of 20 substantially greater internal volume than the amount of hydraulic fluid used in a single actuation of the valve actuator 16. The internal volume is divided by a flexible diaphragm. blocking a gas chamber from a liquid chamber communicating with conduit 25.

The gas chamber is pressurized to a pressure which in the neutral position of the membrane corresponds to the pressure in the high pressure line 8. The central unit has two additional liquid accumulators 37 'and 37' '' of the same type mounted on the block-shaped body 14 near the branches 25 ', 25' '' from 30 the central feed line 25. When the control valves 29 or 31 open, the bulk of the liquid quantity is supplied from the accumulators 37 ', 37' '' on the body 14, and in the subsequent period of closed control valve the accumulators are filled with liquid from the feed line 25. By placing the accumulator 37 near the section 12, a pressure drop in the high-pressure line 8 is counteracted by fluid consumption on the cylinder.

The block-shaped body further contains drainage channels 38 and 39 which drain drained hydraulic fluid from the pump drive and valve actuator to drainage line 23, respectively. There may also be additional control valves such as valves 40 located near the gates on the upper side of body 14.

The hydraulic central unit 11 is shown in more detail in FIG. 4. The bracket 13 is box-shaped and comprises at least two side walls and a front wall giving the bracket great rigidity. The bracket is fixed to a top plate 41 in the engine rack. The top plate carries a cylinder liner 42, the lower section 43 of which has reduced 15 outer diameter and protrudes into the flushing box 44 in the cylinder portion of the stand. The exhaust valve 9 is mounted in a cover 45 which is clamped to the top plate by cover pin 46, only a few of which are shown. A walkway 47 protrudes from the top plate 41. The height of the bracket is adjusted so that the pressure lines 15 and 18 have a short length, which for the larger motors with cylinder bores of at least 500 mm results in bracket heights of 55 to 120 cm. This provides a convenient working height for staff standing on the walkway and having to separate the 25 hydraulic elements mounted on the central unit.

The high pressure line 8 is mounted on a solid steel body 48 extending from one to the other side wall of the bracket. In this steel body, the bore 30 is a channel forming the section 12, and another channel forming the section 26, and the main switch valve 24 is mounted on the front of the steel body, for easy access for operation. The feed conduit 25 is up to the block-shaped body formed as a pipe connected partly to a stud with mounted accumulator 37, and partly to the underside of the body 14. Similarly, the conduits 23 and 27 are designed as pipes in the area below the body 14.

The block-shaped body 14 is of steel, and the large number of internal channels for high-pressure and low-pressure and drainage passages are designed as bores in the steel body. The control valves 29-31 are mounted on the front of the body. The fuel pump and associated drive is mounted directly on the upper side of the body 14, which gives the advantage that the pressure chamber in the drive is in direct contact with the port at the end of the channel 35.

Between the central units 11, the high-pressure tube 8 is formed as an inner tube 49 and a concentric outer tube 50, both of which are high-pressure tubes capable of withstanding the maximum high pressure. The two pipes are mounted between the central units and are supplied as a prefabricated pipe set which can compensate for inevitable variations in the mounting of the central units. The inner tube 49 is inserted at both ends pressure-sealing into a sleeve 51, 51 '20 for clamping on the side surface of the associated central unit, and the inner tube can be longitudinally displaced relative to at least one of the bushings and angularly rotated to a degree of both bushings to compensate for distance and rectification inaccuracies. The outer tube carries at each end a cup-shaped sleeve 52, 52 'which is displaceable in the longitudinal direction of the outer tube and is mountable on the side surfaces of the associated central units. These bushings can also be angled a few degrees relative to the outer tube.

The bushes 52, 52 'have a cup bore of greater diameter than the outer diameter of the bush on the inner tube so that they can be displaced over them.

The present invention is not limited to the above-mentioned concrete example of an embodiment. For example, it is possible to use other types of control valves, such as multi-stage or multiple position valves, the low pressure line may be omitted and replaced by the drain line, and there may be in the body 14 more valves, ducts and drainage passages than mentioned. It is also possible to provide additional types of hydraulically actuated cylinder elements from the central unit, for example a hydraulically driven cylinder lubricator. The cylinder lubricator may be mounted on the block-shaped body.

Claims (11)

1. Hydraulic central unit (11) for a cylinder in an internal combustion engine (2), said engine having several fuel pumps (10) and several exhaust valves (9), wherein 5. the smallest exhaust valves are actuated by hydraulic drive devices by means of pressurized hydraulic fluid, characterized the central unit having a block-shaped body (14) comprising at least one port for connecting at least one pressure conduit 10 (15) for the actuator of the exhaust valve and control valves (30, 31) for controlling at least the exhaust valve and internal ducts ( 25, 25 ', 25' ', 25' '', 27, 27 ', 27' ', 27' ', 34) connecting via the control valves to the ports with connections for a high pressure line (15) 15 for supplying the pressurized hydraulic fluid or a drain or low pressure line (22, 23) for releasing the hydraulic pressure, and that the central unit has a main switch valve (24) which is in an open position and in a closed position at least high pressure line (8) ) from the control unit of the central unit. Hydraulic central unit according to claim 1, characterized in that the main switch valve (24) in its closed position connects a drain line (23) with the inner main channel which in the open position of the main switch valve communicates with the high pressure line (8). Hydraulic central unit according to claim 1 or 2, characterized in that the central unit comprises a bracket (13) mounted on a top plate (41) in a cylinder part, from which the cylinder liner protrudes that the block-shaped body (14) is mounted. on the top of the bracket and that the bracket (13) has a height such that the top of the block-shaped body is at least 80 cm above the top plate. Hydraulic central unit according to one of claims 1-35 3, characterized in that there is one central unit (11) per cylinder. Hydraulic central unit according to one of claims 1-4, characterized in that each central unit contains a section (12) of the high-pressure line located in the supporting bracket (13) under the block-shaped body and that the main switch valve (24) is located in the the flow path between this section and the block-shaped body. Hydraulic central unit according to one of claims 1 to 10, characterized in that the fuel of the cylinder is supplied by a hydraulic driven fuel pump (10) of the piston type, the hydraulic drive of which is connected to at least one port in the block-shaped body (14) for connection with the high-pressure line (8) and the drain or low-pressure line (22, 23), and the control valve (29) of the block-shaped body controls the fuel delivery from the piston pump independently of the control valve (30) of the exhaust valve actuator. Hydraulic central unit according to claim 6, characterized in that the fuel pump (10) and its associated hydraulic drive are mounted on the upper side of the central unit's block-shaped body (14). Hydraulic central unit according to one of the preceding claims, characterized in that the control valves (29, 30) in the central unit are electronically controlled by a motor control unit and / or a cylinder control unit (19). Hydraulic central unit according to one of claims 1-8, characterized in that the hydraulic central unit (11) is connected to the low pressure pressure line (22) which supplies hydraulic fluid at a low pressure, preferably less than 4 bar. Hydraulic central unit according to one of the preceding claims, characterized in that the central unit (11) has at least two high-pressure fluid accumulators (37, 37 ') connected to the high-pressure channels located on the away from the high-pressure line (8). side of the main switch valve (24). Hydraulic central unit according to one of the preceding claims, characterized in that the central unit (11) contains a section (12) of the high-pressure line (8) connected to another central unit by means of two concentric high-pressure pipes which are mounted between the central units, that the two concentric high-pressure tubes are an inner tube (49), which is at both ends pressure-sealed into a socket (51, 51 ') for fixed tension on the side surface of the central unit, and an outer tube (50) which at each end carries a cup-shaped bush (52, 52 ') which is slidable on the outer tube in its longitudinal direction and is mountable on the side surface of the central unit and has a cup bore of greater diameter than the outer diameter of the bush on the inner tube.