EP2545257A1

EP2545257A1 - Dosing system for lubricating oil for large diesel engines and method for dosing cylinder lubricating oil to large diesel engine cylinders

Info

Publication number: EP2545257A1
Application number: EP11709319A
Authority: EP
Inventors: Peer Bak
Original assignee: Hans Jensen Lubricators AS
Current assignee: Hans Jensen Lubricators AS
Priority date: 2010-03-12
Filing date: 2011-03-10
Publication date: 2013-01-16
Anticipated expiration: 2031-03-10
Also published as: JP5266356B2; WO2011116768A1; JP2011190807A; KR101569564B1; CN103249922B; DK177620B1; CN103249922A; EP2545257B1; KR20130044224A; DK201070098A

Abstract

There is described a dosing system for cylinder lubrication oil for large diesel engine cylinders (5), e.g. in marine engines (32), and including: a central lubricating oil supply, e.g. a central pump station (1);a supply line (31) and a return line (33) to/from the lubricating oil supply for circulating the lubricating oil;a number of injectors (6) corresponding to the number of cylinders in the engine or a multiple thereof, and which are adapted to inject cylinder lubricating oil into an associated cylinder via a nozzle aperture (20), and which via branch lines (7, 15, 16) are connected with the supply and return lines;opening/closing valve units (3) provided in the branch lines (15, 16) between the injectors (6) and the supply and return lines; and a control unit(25) controlling each opening/closing valve unit (3). In order to achieve a flexible central control of injected amount of oil and precise control of timing, the system is designed such that the opening/closing valve units (3) have a first inlet (P) and a first outlet (R) which may connect a first chamber (22) behind a spring-biased closing member (18) in the injectors with the supply line (31) and the return line (33), respectively. The injector (6) further has a second chamber (24) in front of the closing member (18) of the injector, where the second chamber is connected with a branch line (7) connecting the second chamber (24) of the injector with the supply line (31).The control unit (25) is at least connected with the opening/closing valve units (3).

Description

Dosing System for Lubricating Oil for Large Diesel Engines and Method for Dosing Cylinder Lubricating Oil to Large Diesel Engine Cylinders

Field of the Invention

The present invention concerns a dosing system for cylinder lubrication oil to large cylinders in a diesel engine, e.g. in marine engines, including:

- a central lubricating oil supply that may be constituted by a central pump station or a central accumulator;

- a supply line from the lubricating oil supply;

- a number of injectors corresponding to the number of cylinders in the engine or a multiple thereof, and which are adapted to inject cylinder lubricating oil into an associated cylinder via one or more nozzle apertures, and which via branch lines are connected with the supply lines;

- opening/closing valve units provided in the branch lines between the injectors and the supply lines; and

- a control unit controlling each opening/closing valve unit.

The invention furthermore includes a method for dosing cylinder lubricating oil to cylinders in a large diesel engine, for example in marine engines, including steps for pressurising the lubricating oil in a central lubricating oil supply that may be constituted by a central pump station or a central accumulator; supplying the lubricating oil through a supply line; injecting cylinder lubricating oil into an associated cylinder via a number of injectors that correspond to the number of cylinders in the engine or a multiple thereof, and which each are adapted with one or more nozzle apertures; and which via branch lines are connected with the supply lines by opening and closing the opening/closing valve units disposed in the branch lines; and controlling each opening/closing valve unit by means of a control unit.

Background of the Invention

Traditionally, it has been common to use lubricating apparatuses which are mechanically connected with and driven by the crankshaft on the engine to be lubricated. These are systems where there is limited flexibility in changing the supplied lubricating oil portion, in particular if there is to be performed a change while the engine is running. Many examples of systems for cylinder lubrication are known where it is intended to achieve a flexible and precise timing and amount for cylinder lubrication independently of the crankshaft of the engine.

An example of a system for cylinder lubrication of the type mentioned in the introduction and which may easily be mounted in a large diesel engine with a plurality of cylinders, is disclosed in EP 1 426 571. The system enables electronic control of the amount of oil injected in dependence of the need arising during a given situation of operation. The described system put great demands on tightness due to the high closing pressures required in the opening/closing valves which are provided in branch lines between the injectors and the supply line from the pressure source. This is particularly the case in systems where cylinder lubrication is established with an injection of lubricating oil under high lubricating oil pressures, e.g. 40 bar or higher. Moreover, the disclosed system put veiy high demands on uniform viscosity, uniform pressure conditions, uniform temperature, uniform tube lengths etc, in order to establish exact control of the delivered amount of lubricating oil per time unit. This further provides an uncertainty with a precise control of timing for the oil injection.

By a system according to the present invention, advantages may be achieved when operating at a lower pressure, e.g. between 25 and 70 bar, though typically at 40 bar and above.

Object of the Invention

It is the purpose of the present invention to provide a technically simple system for electronically controlled lubrication of cylinders in large diesel engines whereby it is possible to achieve a flexible central control of injected amount of oil and precise control of timing. It is particularly the object to indicate a system for injecting lubricating oil for lubricating the cylinders by lubrication at high lubricating oil pressures, for example at 40 bar and above, and to indicate a system which is more stable regarding lubricating oil viscosity and pressure conditions in the supply lines than is the case with the prior art systems. Description of the Invention

According to the present invention, this is achieved by a system of the type specified in the introduction which is peculiar in that the injectors via second branch lines is connected with a return line to the lubricating oil supply for circulating the lubricating oil, that the opening/closing valve units is connected with the return line as they are provided in the second branch lines between the injectors and the return line, that the opening/closing valve units have a first inlet and a first outlet which connect a first chamber behind a spring-biased closing member in the injectors with the supply line and the return line, respectively, that the injector has a second chamber in front of the closing member of the injector, where the second chamber is connected with a third branch line connecting the second chamber of the injector with the supply line, and that the control unit is at least connected with the opening/closing valve units.

The method according to the invention is peculiar in that the injectors via second branch lines is connected with a return line to the lubricating oil supply for circulating the lubricating oil, that the opening/closing valve units is connected with the return line as they are provided in the second branch lines between the injectors and the return line, that the opening/closing valve units via a first inlet and a first outlet connect a first chamber behind a spring-biased closing member in the injectors with the supply line and the return line, respectively, that the injector has a second chamber in front of the closing member, connecting said second chamber with a third branch line which connects the second chamber of the injector with the supply line, and that control of the oil dosing is performed by opening and closing the opening/closing valve units in the branch lines between the injectors and the return line.

The system according to the present invention is thus based on the feature that the chamber of the injectors in front of the closing member is constantly connected with the supply line and thus is under a constant feed pressure supplied by a lubricating oil pump. This lubricating oil pump may be electrically or mechanically driven.

The chamber of the injectors behind the closing member is connected with the supply line and is thus under the same pressure as the pressure prevailing in the chamber in front of the closing member when the injectors are closed, as the closing member is urged against the nozzle aperture by a spring. The injector is opened by removing the pressure in the chamber behind the closing member. This is effected by resetting the opening/closing valve units and connecting the chamber behind the closing member with the return line. The pressure in the lubricating oil in the chamber in front of the closing member will hereby overcome the force from the spring such that the closing member is displaced away from the nozzle aperture. Hereby, injection is immediately effected at a pressure which from the start of injection corresponds to the pressure in the lubricating oil. The pressure in the supply line may typically be 70 bars or higher. The injector is closed by re-establishing the pressure in the chamber behind the closing member. This is effected by resetting the opening/closing valve units and connecting the chamber behind the closing member with the supply line. Hereby, the pressure in the lubricating oil in the chamber behind the closing member together with the spring will overcome the pressure in the lubricating oil in the chamber in front of the closing member such that the closing member is displaced to abut on the nozzle aperture. The injection is immediately interrupted hereby.

The injected amount of oil is controlled by controlling the opening time of the injectors, i.e. the period of time in which the pressure in the chamber behind the closing member is removed. Since there is almost no consumption in the branch line between the injector and the return line for opening and closing the injectors, these may be controlled veiy accurately.

The opening times of the injectors may be derived from empirical values. These empirical values may include data for oil, pressure, flow, lubricating oil demand etc., and may be stored in the control unit. These data are used for controlling movements of the opening/closing valve units and thereby the opening times of the injectors.

The empirical values applied may possibly be corrected on the basis of data from measurements of the oil flow.

The system may operate with one or two simple lubricating oil pumps. These may have relatively low capacity as the pump capacity is only to be slightly greater than the maximum lubricating oil consumption of the engine. At the same time, the pump energy is converted into heating of the lubricating oil and the opening/closing valve units. The system is intended for use by various kinds of cylinder lubrication, e.g. SIP lubrication (e.g. described in WO 0028194), spray lubrication, jet lubrication with one or more oil jets per injector (e.g. described in EP 1 350 929), pulsejet lubrication (e.g. described in brochures from Wartsila) or combinations thereof. When the system is explained based on specific application areas, e.g. SIP lubrication, this is not to be regarded as a limitation of the system but only as an example of the particular advantages achieved by the system.

All vulnerable functions, as stroke setting, over-pressure valves for the SIP valves with monitoring and function sensors are superfluous. The only elements left are the two interconnected solenoid valves and possibly a simple volume meter, for example in the form of an oval wheel meter.

It is noted that a system according to an alternative embodiment can be designed without a volume meter. By empirical work (or constiiiction-specific work by installation) the correlation between "opening times" and delivered lubricating oil amounts for a system are determined. The need for a volume meter or flow metering will hereby be redundant.

In such a system without a volume meter, one will preferably design tubing, valves, pumps etc such that a constant temperature of lubricating oil/tubing is ensured.

At the same time it is assumed that the sensitivity of the SIP valves to micro-particles in the lubricating oil is reduced as pressure drop over the needle guide only exists when the valves are open. There will be no risk either of the valves opening to the cylinder pressure since the closing pressure will be much higher at all times. The injectors may be simplified as requirements to tolerances and fits between the closing member/needle and chamber/guide can be reduced as the influence of these on the delivered amount of lubricating oil may by and large be ignored. According to a further embodiment of the invention, the dosing system is peculiar in that in the branch line connecting the second chamber of the injector with the supply line, a volume meter is disposed for measuring the added lubricating oil volume per cylinder, and that the control unit is connected with the volume meter. According to a further embodiment of the invention, the method is peculiar in that a volume measurement of the supplied lubricating oil portion per cylinder is performed in a branch line connecting a second chamber in front of the closing member of the injector with the supply line. The injector chamber from which injection is performed is supplied with lubricating oil through the volume meter which is inserted in a common tube connecting them with the supply line.

Hereby it becomes possible to measure the supplied oil volume per cylinder and thereby to determine the injection time for a given oil consumption. Preferably, the supplied amount of oil per cylinder is measured by a volume meter, for example in the form of an oval wheel meter. The time for injection may be regulated over a PID (Proportional-Integral-Derivative) regulating loop. This is a closed-loop regulation where compensation is made for possible deviations that are measured.

The volume meter is used simultaneously for monitoring the function of the dosing system. If no consumption is shown, something is wrong. If it shows deviating consumption in excess of expected values, it can be assumed that an injector is leaking or clogged.

Other alarm function which may be monitored via detectors and detected by the control unit are failing oil pressure, too high counterpressure in filters, too high or low oil temperature, or computer-related errors. The control unit includes an electronic control system which is based on a computer that may have extension cards for engines with more than eight cylinders.

There may also be provided a backup system which includes readily exchangeable units, injectors, opening/closing valve units, computer prints, etc, or duplication of functions. For example, large engines may be divided such that there are two computers, two opening/closing valve units, two transmitters and two networks. One system controls eveiy other injector in a cylinder and the other system controls the remaining injectors. In case of error, the faulty system is stopped and the other system continues with double amount until the error has been corrected.

According to an alternative embodiment, the method is peculiar in that an empirical determination of the correlation between opening times and delivered amounts of lubricating oil is established for a system, and that these data are stored in the control unit and used for controlling the oil dosing.

The system may be designed without volume meter/volume measurement. By empirical work (or constniction-specific work by installation) the correlation between "opening times" and delivered lubricating oil amounts for a system are determined. The need for a volume meter or flow measurement will hereby be redundant.

In such a system without a volume meter, one will preferably design tubing, valves, pumps etc such that a constant temperature of lubricating oil/tubing is ensured. According to a further embodiment of the invention, the dosing system is peculiar in that the opening/closing valve unit is connected such that the first and second chamber of the injectors are connected with the supply line in the closed condition of the injector, and such that the first chamber of the injectors is connected with the return line in the open condition of the injector. By the tube system for each engine cylinder, a number of injectors are thus connected to an opening/closing valve unit which through a common tube is connected to the return oil side of the injectors. According to a further embodiment of the invention, the method is peculiar in that the first and second chambers of the injectors formed behind and in front of, respectively, the closing member of the injector are connected with the supply line in the closed condition of the injector, and that the first chamber of the injectors is connected with the return line in the open condition of the injector.

According to a further embodiment of the invention, the dosing system is peculiar in that one opening/closing valve unit and one volume meter (if a volume meter is used) is provided for all injectors that are mounted in one cylinder. This enables simplification of the design of the dosing system, and also simplifies the control compared with a system in which an opening/closing valve unit and a volume meter are mounted for each injector.

According to a further embodiment of the invention, the dosing system is peculiar in that the opening/closing valve unit is connected via a port with each of the injectors via connecting tubes which are equally long. Hereby is ensured uniform response time for the individual injectors as the length of the individual tube sections on the return side of the injectors is the same for all injectors as far as possible. According to a further embodiment of the invention, the dosing system is peculiar in that the supply line and the return line at their end farthest from the lubricating oil supply include a pressure valve which ensures a controlled circulation of the lubricating oil. Lubricating oil pumps with filters and motor boards and other elements can be mounted at the end of the engine or at another suitable place.

The tube system for the lubricating oil will preferably include the supply line for conducting lubricating oil under pressure and the return line for returning excess lubricating oil to the lubricating oil pump, and these will be mounted along the longitudinal axis of the engine. The pressure valve of the oil system is mounted at the opposite end of the engine relative to the lubricating oil pumps such that the oil is continuously circulated in the entire tube system. The pump energy is hereby converted into heating of the lubricating oil in the tubing, and it is possible to ensure a uniform temperature. This will prevent local overheating of the oil, and it is possible to eliminate the need for cooling the lubricating oil.

According to a further embodiment, the dosing system according to the invention is peculiar in that the opening/closing unit includes at least two interconnected valves.

The opening/closing valve unit controlling the pressure in the branch line connected with the return line may thus include two solenoid valves that are interconnected such that they separately control opening time and closing time, respectively.

The opening/closing valve unit is disposed opposite each cylinder if they are redundant, otherwise between two cylinders. They may be connected to a pipe system on the cylinder via two short tubes if the cylinder is formed with pre-mounted injectors and tubing for connecting these injectors. For easy separation, hoses and connectors can be used as alternative to the two connecting tubes.

The opening/closing valve unit typically consists of two three-way solenoid valves that are connected in such a way that one valve opens for the injectors by lowering the pressure in the return line of the injectors, and the other valve closes the injectors by pressurising the return line of the injectors again.

The reason for using two valves is that the opening time of the injectors is only a few milliseconds, depending on the desired amount of oil to be delivered by the injector. Normal commercially available solenoid valves have much longer response time than required for achieving small amounts of injected lubricating oil. By applying an overlap of the movement for the two valves it becomes possible to achieve veiy short opening times for the injectors and thereby also possibility of precise delivery of even small portions of lubricating oil by using simple and cheap valves that have long response times.

Alternatively, it is also possible to use a fixed overlap between the movement of the two valves and to vaiy the pressure in the supply line in order thereby to adjust the amount of injected lubricating oil. This is particularly an advantage by injecting small amounts of lubricating oil.

It is prefeired that each opening/closing valve unit and volume meter is connected with the computer via a shielded cable, for example an eight-pole shielded cable (two poles per solenoid valve and four poles for the volume meter). It is also possible advantageously to use one cable for power supply and one for signal transmission in order to reduce the number of conductors to be lead into the computer. The system may thus be provided a veiy simplified tubing and cabling. A display can be fitted on or close to the engine. Simple functions can be set and read on it. General functions and settings are usually based on a computer placed in a control room.

The lubricating oil portion for each individual cylinder may be controlled by measuring the actual consumption, and through a regulating loop the opening time for opening/closing valve unit can be adjusted for attaining the desired amount of lubricating oil.

The lubricating time and the lubricating oil amount are controlled by the control unit which controls each opening/closing valve unit based on given data and measurements which are stored in or measured via sensors and transmitted to the control unit. The volume meter thus performs a monitoring function of the injectors in the individual cylinder unit in that the control unit compares the actual consumption with the expected consumption at the given pressure and temperature of the oil which will deviate in case that a nozzle is leaking or clogged.

According to a further embodiment of the invention, the method is peculiar in that control of the oil dosing includes control of opening times and holding times for at least two valve elements in the opening/closing valve unit. As mentioned, this provides a veiy simple possibility of precise adjusting even small lubricating oil portions. The control unit may form part of a computer system with a central computer that establishes a control of the system according to the invention. According to a special embodiment, the central computer comprises two PCs: A main PC and a backup PC. The control is made so flexible that all current operational modes can be applied:

- rpm-dependent regulation, i.e. unregulated operation;

- bhp-dependent regulation, i.e. load dependent regulation of the amount of lubricating oil;

- mep-dependent regulation, i.e. cylinder pressure dependent regulation of lubricating oil; or

- load change dependent regulation, i.e. extra lubrication in connection with changes in load.

Besides, it is possible to establish a flexible control system enabling a high degree of user specified regulating algorithms, including:

- variants of standard operational modes;

- possibility of regulating algorithms that are entirely or partly based on customer- specific data input, e.g. diverse sensor based data input (FE-content, cylinder pressure, cylinder temperature etc. ), where the inputs may be applied to the entire engine or to the individual cylinder;

- possibility of overlay modes where the user defines and describes reduction and/or increase percentages by himself.

The control is performed with the possibility a local data collection in/at the individual cylinder and a superior control with the possibility of controlling the delivered amounts of lubricating oil corresponding to the expected/planned amounts of lubricating oil.

It is possible to establish a local control whereby the user has the possibility of performing a local data collection in/at the individual cylinder and using these online data inputs for adjusting supply amounts and possible timing. One may e.g. mount temperature sensors in the cylinder and flowmeters on the fuel supply for individual cylinders and subsequently define how the control is to regulate timing and amounts in relation thereto. To this is added that local information about conditions for individual cylinders may be gathered; e.g. it will be possible to mount flowmeters and/or temperature sensors by the individual injectors, and via the network supply this information about conditions to a superior control, in that way achieving the possibility of e.g. checking if the supplied amounts of lubricating oil correspond to the expected/planned amounts of lubricating oil.

Moreover, flow measurement can be performed by alternative methods. Instead of controlling the function via the flowmeter, a monitoring of the two valve slides changing position may be incorporated. For example, one or two induction encoders may be incorporated for each valve. These encoders detect when the valve slides are in the relevant extreme positions. Such an alternative solution may optionally be combined with mounting two flowmeters on the supply and the return line, respectively, in immediate continuation of the pump stations. Hereby it is possible to control the total consumption for the whole system.

According to a further alternative, the flowmeters can be changed from being a local unit per dosing unit to a system where two flowmeters are used on the supply and the return lines, respectively, in immediate continuation of a pump station. The entire consumption for the whole system may be controlled hereby.

In the above mentioned embodiments, it is assumed that the supply pressure for the injectors is constant. However, it is also possible to have embodiments operating with variable working pressure in the supply line for the lubricating oil. It is thus possible to vaiy the working pressure in dependence of the existing conditions (dosing portions, temperatures, pressure inside the cylinder, the load on the cylinder/engine, etc).

According to a further embodiment, by lesser dosing portions higher supply pressures may be applied in the supply line such that the dosed lubricating oil amount is better distributed. Such a solution will require that a pressure-regulating valve is built in around the pump station such that via the control unit and depending on previously registered data one may perform a stepless regulation of the supply pressure. The dosed oil may hereby be delivered in a form which is optimal according to the conditions.

As a further alternative embodiment, a teclinically simple solution can be made where instead of a stepless pressure regulating valve one may use an on/off solenoid valve that can elevate or lower the pressure level automatically.

Description of the Drawing

The invention will be explained in more detail below with reference to the accompanying drawing, where:

Fig. 1 shows a schematic drawing for constructing a dosing system according to the invention in an engine with five cylinders and with a central lubricating oil supply in the form of a pump station;

Fig. 2 shows a schematic drawing for constructing a valve unit with two three-way valves for use in the dosing system shown in Fig. 1 , and illustrated with three different operating positions A, B and C for the valve unit in closed and open conditions;

Fig. 3 shows a diagram for illustrating the course of an injection cycle over time, where the valve unit shown in Fig. 2 is used in the dosing system shown in Fig. 1 ;

Fig. 4 shows a side view of a valve unit;

Fig. 5 shows a side view of the valve unit shown in Fig. 4 according to the arrows V-V in Fig. 4;

Fig. 6 shows a view corresponding to Fig. 1 but for illustrating a system where a central lubricating oil supply in the form of a central accumulator is used; Fig. 7 shows a view corresponding to Fig. 1 but for illustrating a system where flowmeters are used on the supply and return lines, respectively;

Fig. 8 shows a view corresponding to Fig. 1 but for illustrating a system where flowmeters are used on the supply and return lines, respectively, together with detection of the position of the valve slides;

Fig. 9 shows a view corresponding to Fig. 1 but for illustrating a system operating with a variable working pressure in the lubricating oil; and Fig. 10 shows a view corresponding to Fig. 1 but for illustrating a further system operating with a variable working pressure in the lubricating oil.

Detailed Description of Embodiments of the Invention

The system includes a pump station 1. Cylinder lubricating oil is conducted under pressure from the pump station 1 through a supply line 31 running along the five cylinders 5 in the engine 32 to a pressure valve 2 at the end of the engine 5. Excess lubricating oil is conducted through a parallel return line 33 back to the pump station. The energy of the pump is hereby converted into heating of the lubricating oil in the supply and return lines 31 , 33, ensuring reasonably constant temperature of the oil in the supply and return lines and preventing local overheating of the oil. The pump station 1 is supplied with oil through a supply line 34.

The pump station 1 includes two pumps 1 1 , two filters 12 and two check valves 13 preventing the lubricating oil from running back through a still-standing pump 1 1. The pump station also includes two shut-off valves 14 that are inserted in the supply line 34 so that the filters 12 can be cleaned during operation. The two pumps 1 1 are stand-by for each other and start up automatically in case of a drop in oil pressure.

To the supply and return lines 31 , 33 and for each engine cylinder 5 there is connected an opening/closing valve unit 3 having a port P which is connected with the supply line

31 , and a port R connected with the return lines 33 via first and second branch lines 15,

16. Each opening/closing valve unit 3 has a port A which through a common tube 8 is connected with a number of lubricating oil injectors 6 mounted in the engine cylinder 5.

The common tube 8 is connected with the return line 17 (see Fig. 2) of the injectors. The injectors 6 are supplied with lubricating oil for injecting into the engine cylinder 5 from the supply line 31 through a third branch line 7 in which is mounted a volume meter 4.

As mentioned above, a system may alternatively be designed without a volume meter. By empirical work (or constiiiction-specific work by installation), the correlation between "opening times" and delivered lubricating oil amounts for a system are determined. The opening/closing valve unit 3 consists of two three-way valves VI and V2 (typically solenoid valves) that are connected as shown in Fig. 2. For illustration, only one injector 6 associated with the opening/closing valve unit 3 is shown in Fig. 2. Each valve unit has two ports P which are connected with the supply line 31 , and a port R connected with the return line 33. Furthermore, the two valves V I and V2 are interconnected via the ports B and C.

Furthermore is seen a control unit 25 which via a connection 26 is connected with opening/closing valve unit 3 that receives control signals from the control unit and which transmits feedback information to the control unit 3. Via a connection 27, the control unit 25 receives feedback information from the volume meter 4. These connections will be provided in a number corresponding to the number of cylinders in the engine. The control unit will furthermore have a number of further connections for normal operation with feedback signals, e.g. from crankshaft, engine load, pressure conditions, lubricating oil temperature, pre-programmed data and the like, and control signals, e.g. for alarms, continuous data collection and similar. In Fig. 2A the injector 6 is seen with a closing member 18 having a pointed end 19 which closes the nozzle opening 20 of the injector 6 through which a lubricating oil spray 21 (see Fig. 2B) is injected in the cylinder 5. At a rear end of the closing member 18 there is formed a first chamber 22 where a spring 23 is provided pressing the closing member into closing abutment against the nozzle aperture 20. In front of the closing member 18 and around the point is formed a second chamber 24 which is provided with lubricating oil for injection into the engine cylinder 5 from the supply line 31 through the branch line 7.

It appears that the return line 17 of the injector is under full supply pressure via the port A and the common tube 8 when the injector is closed. One valve VI thus opens for the injector 6 by lowering the pressure in the return line 17 of the injector, and the other valve V2 closes the injector 6 by pressurising the return line 17. Fig. 2B shows VI activated, and the pressure in the first chamber 22 of the injector behind the closing member may escape through VI and V2 to return port R which has a much lower pressure than the supply port P. The supply pressure in the lubricating oil from branch line 7 surmounts the spring pressure and forces the closing member 18 back from its closing abutment against the nozzle aperture 20 such that the lubricating oil 21 is injected into the cylinder 5. This occurs by the high supply pressure prevailing in the second chamber 24 from the beginning of the injection.

Fig. 2C shows both V I and V2 activated. Hereby, V2 opens for the port P which is connected with the supply line 31 , and the oil is pressed through V I into the first chamber 22 and is applied to the back side of the closing member 18. The pressures on both sides of the closing member 18 are hereby equally large so that the spring 23 will push the closing member forward and close the nozzle aperture 20. Then V I is deactivated in order to maintain the pressure on the back side of the injector before V2 can be deactivated and a new cycle be re-started.

By using two valves V I and V2 it is possible to achieve that the opening time of the injector 6 is only a few milliseconds, depending on the desired amount of oil to be delivered by the injector.

Fig. 3 shows the course of an injection cycle over time. The control unit 25 is provided a position signal 28 at the time Tl for the crank angle and thereby the position of the piston in the cylinder 5, and emits an activation signal at the time T2 for the valve V I . The valve VI starts injection of lubricating oil in the cylinder at the time T3 with a delay 29 indicated by T3-T2. The control unit 25 also sends an activation signal T4 to the valve V2 in order to stop injection of lubricating oil. The valve V2 is activated and stops injection of lubricating oil at the time T5 with a delay 30 indicated by time interval T5-T4. Deactivating the valves V I and V2 occurs at the times T6 and T7. The lubricating oil portion for the individual cylinder 5 is controlled by measuring the actual consumption by the volume meter 4, and by feedback to the control unit 25, the opening time for the injector 6 is adjusted if a deviation from a given value stored in the control unit occurs. The lubricating time and the lubricating oil amount are controlled by the control unit 25 which controls the opening/closing valve unit 3 of each cylinder 5 based on given data and measurements which are stored in the control unit 25. In order to ensure uniform response time for the individual injectors 6, the common tube 8 is divided on the return side of the injectors into single pieces of tubing such that the tube lengths 8 between respective injectors 6 and associated opening/closing valves 3 are the same. At the same time, the volume meter 4 has the function of monitoring that the control unit 25 is operating. The volume meter 4 detects a consumption when activated by the control unit 25. The individual injectors 6 for each cylinder 5 are also controlled in that the control unit 25 compares the actual consumption with the expected value at the given pressure and temperature of the oil. Deviations will, for example, appear if an injector 6 is leaking or clogged. The control unit 25 consequently emits an alarm.

In order to achieve additional reliability, the system may be doubled such that eveiy other injector 6 in a cylinder 5 is supplied from an independent lubricating system with all functions, and the other half from a corresponding unit, monitoring each other, and in case of error the normally operating system takes over the entire cylinder lubrication by doubling the amount of lubricating oil delivered from its half of the number of nozzles.

An airangement for the opening/closing valve unit 3 for two cylinders 5 is shown in Figs. 4 and 5. The shown airangement is provided by means of fittings 35 and mounting screws 36 between the two cylinders 5. The shown unit is constincted with two identical opening/closing valve units 3 in order to get redundancy.

Each of the two opening/closing valve units 3 have a valve block 37 with a switch valve 38 that may be set in an open and a closed position. The airangement further includes a flow control block 39 and a terminal box 45 with flow indicator 40 and on/off indicators 41 , 42 for the solenoid valves and a valve control block 43 upon which the two solenoid valves 44 are fastened. Connecting lines 8, 15, 16 and ports A, P, R are provided with the same reference numbers which are indicated in connection with the description of the system shown in Fig. 1.

Fig. 6 shows an alternative embodiment of the system shown in Fig. 1. Identical and corresponding elements will be designated with the same reference number. In the system shown in Fig. 6 there is used a central accumulator 100 for oil deliveiy instead of deliveiy directly from the central pump unit 1. By using the central accumulator 100 it is possible to even out possible pressure variations in a particularly safe way. The pressure thus becomes more uniform, and at the same time it becomes easier to control the delivered amount of lubricating oil.

In Fig. 6 is furthermore marked a further embodiment of a system according to the invention by broken lines, and here local accumulators 101 are shown. In this embodiment, the central accumulator 100 will thus normally not be present, but there will still be a central lubricating oil supply 1. Local accumulators 101 are disposed in the branch line 7 between the supply line 31 and the injector 6. The local accumulator 101 is shown right in front of the volume meter 4 but it may alternatively be disposed right behind the volume meter. A local accumulator 101 is shown per cylinder. In Fig. 6 is shown examples of feedback signals received by the control unit 25 and examples of signals and data transmitted from the control unit 25.

In Fig. 7 is shown an embodiment where two flowmeters 1 10 and 1 1 1 are mounted on the supply line 31 and the return line 33 in immediate connection to pump station 1. Hereby it is possible to control the total consumption for the whole system.

In Fig. 8 is shown an embodiment in which is mounted a monitoring of the two valve slides changing position. For example, one or two induction encoders may be incorporated for each valve. These encoders detect when the valve slides are in the relevant extreme positions and transmit a signal 109 to the control unit 25. Such an alternative solution may optionally be combined with mounting two flowmeters 1 10 and 1 1 1 such as shown in Fig. 8. Hereby it is possible to control the total consumption for the whole system. Under some conditions, it may be desirable to adapt the deliveiy characteristic of the supplied lubricating oil through the injector. This may be achieved by varying the pressure in the supply line 31 and thereby also the branch line 15. A further control parameter is added hereby, enabling changing the propagation, composition (e.g. drop size, amount and density) and the speed of the delivered lubricating oil. The pressure variation may depend on dosing amounts, temperatures, pressure inside the cylinder, cylinder/engine load etc, and

for example,

Faster deliveiy of oil at higher pressure in the supply line 31 ;

Finer spray/jet(s) at higher pressure in the supply line 31.

In Fig. 9 appears a system operating with variable working pressure in the lubricating oil. The pressure valve 2 is replaced by two pressure valves 1 12 and 1 13 with each their pressure setting, where pressure valve 1 12 is set to a higher pressure than pressure valve 1 13. By means of a solenoid valve 1 14, access to valve 1 12 may be blocked and the pressure is thereby adjusted to the level of pressure valve 1 13. The reference number 1 16 indicates a connection between the control unit 25 and the pressure valve 1 14. In Fig. 10 is shown an alternative embodiment, where instead of the pressure valve 2 there is used a stepless, electrically regulated pressure valve 1 15 which provides the most flexible control. It appears that also the pressure valve 1 15 is connected via the connection 1 16 to the control unit 25 from where the pressure is controlled in dependence on the conditions.

As a further alternative embodiment, a teclinically simple solution can be made where instead of a stepless pressure regulating valve one may use an on/off solenoid valve which may automatically elevate or lower the pressure level.

Claims

C LAI M S

1. A dosing system for cylinder lubrication oil to large cylinders (5 ) in a diesel motor, e.g. in marine engines, including:

- a central lubricating oil supply that may be constituted by a central pump station ( 1 ) or a central accumulator;

- a supply line (31 ) from the lubricating oil supply;

- a number of injectors (6) corresponding to the number (5 ) of cylinders in the engine (32 ) or a multiple thereof, and which is adapted to inject cylinder lubricating oil (21 ) into an associated cylinder (5 ) via one or more nozzle apertures (20), and which via branch lines ( 15 ) are connected with the supply lines (31 );

- opening/closing valve units (3 ) provided in the branch lines ( 15 ) between the injectors (6) and the supply lines (31 ); and

- a control unit (25 ) controlling each opening/closing valve unit (3 ), characterised in that the injectors (6) via second branch lines ( 16) is connected with a return line (33 ) to the lubricating oil supply for circulating the lubricating oil, that the opening/closing valve units (3 ) is connected with the return line (33 ) as they are provided in the second branch lines ( 16) between the injectors (6) and the return line (33 ), that the opening/closing valve units (3 ) have a first inlet (P) and a first outlet (R) which connect a first chamber (22 ) behind a spring-biased closing member ( 18 ) in the injectors with the supply line (31 ) and the return line (33 ), respectively, that the injector (6) has a second chamber (24) in front of the closing member ( 18), the second chamber (24) connected with a third branch line (7 ) which connects the second chamber (24) of the injector with the supply line (31 ), and that the control unit (25 ) is at least connected with the opening/closing valve units (3 ).

2. Dosing system according to claim 1 , characterised in that in the branch line (7) connecting the second chamber (24) of the injector with the supply line, a volume meter (4) is disposed for measuring the added lubricating oil volume per cylinder, and that the control unit (25 ) is connected with the volume meter (4).

3. Dosing system according to claim 1 or 2, characterised in that the opening/closing valve unit (3 ) is connected such that the first (22 ) and second (24) chamber of the injectors are connected with the supply line (31 ) in the closed condition of the injector, and such that the first chamber (22 ) of the injectors is connected with the return line (33 ) in the open condition of the injector.

4. Dosing system according to any preceding claim, characterised in that one opening/closing valve unit (3 ) is provided for all injectors (6) that are mounted in one cylinder (5 ).

5. Dosing system according to claim 2 or 3, characterised in that one opening/closing valve unit (3 ) and one volume meter (4) is provided for all injectors (6) that are mounted in one cylinder (5 ).

6. Dosing system according to claim 4 or 5, characterised in that the opening/closing valve unit (3 ) is connected via a port (A) with each of the injectors (6) via connecting tubes (8) which are equally long.

7. Dosing system according to any preceding claim, characterised in that the supply line (31 ) and the return line (33 ) at their end farthest from the lubricating oil supply include a pressure valve (2 ) which ensures a controlled circulation of the lubricating oil.

8. Dosing system according to any preceding claim, characterised in that the opening/closing valve unit (3 ) includes at least two interconnected valves (V I , V2 ).

9. A method for dosing cylinder lubricating oil to large cylinders in a diesel engine (32 ), for example in marine engines, including steps for pressurising the lubricating oil in a central lubricating oil supply that may be constituted by a central pump station ( 1 ) or a central accumulator; supplying the lubricating oil through a supply line (31 ); injecting cylinder lubricating oil into an associated cylinder (5 ) via a number of injectors (6) that correspond to the number of cylinders in the engine or a multiple thereof, and which each are adapted with one or more nozzle apertures (20); and which via branch lines (7, 15 ) are connected with the supply line (31 ) by opening and closing the opening/closing valve units (3 ) disposed in the branch lines ( 15 ); and controlling each opening/closing valve unit (3 ) by means of a control unit (25 ), characterised in that the injectors (6) via second branch lines ( 16) is connected with a return line (33 ) to the lubricating oil supply for circulating the lubricating oil, that the opening/closing valve units (3 ) is connected with the return line (33 ) as they are provided in the second branch lines ( 16) between the injectors (6) and the return line (33 ), that the opening/closing valve units (3 ) via a first inlet (P) and a first outlet (R) connect a first chamber (22 ) behind a spring-biased closing member ( 18 ) in the injectors with the supply line (31 ) and the return line (33 ), respectively, that the injector (6) has a second chamber (24) in front of the closing member ( 18 ), connecting said second chamber (24) with a third branch line (7 ) which connects the second chamber (24) of the injector with the supply line (31 ), and that control of the oil dosing is performed by opening and closing the opening/closing valve units (3 ) in the branch lines ( 16) between the injectors and the return line (33 ).

10. Method according to claim 9, characterised in that a volume measurement of the supplied lubricating oil portion per cylinder is performed in a branch line (7) connecting a second chamber (24) in front of the closing member ( 18 ) of the injector with the supply line (31 ).

1 1. Method according to claim 9, characterised in that an empirical determination of the correlation between opening times and delivered amounts of lubricating oil is established for a system, and that these data are stored in the control unit and used for controlling the oil dosing.

12. Method according to any of claims 9 - 1 1 , characterised in that the first and second chambers (22, 24) of the injectors formed behind and in front of, respectively, the closing member of the injector are connected with the supply line (31 ) in the closed condition of the injector, and that the first chamber (22) of the injectors is connected with the return line (33 ) in the open condition of the injector.

13. Method according to any of claims 9 - 12, characterised in that control of the oil dosing includes control of opening times and holding times for at least two valve elements (V I , V2) in the opening/closing valve unit (3 ).

14. Method according to any of claims 9 - 13, characterised in that control of the oil dosing includes a variable pressure in the supply line.