KR20170134243A - Fuel or lubrication pump for a large two-stroke compression-ignited internal combustion engine - Google Patents

Abstract

The present invention relates to a pump for supplying fuel or lubrication to a large two-stroke compression ignited internal combustion engine. The pump (40) includes two or more of pump portions (41, 42, 43). Each of the pump portions (41, 42, 43) includes a pump piston (62) slidably disposed in a pump cylinder (61) and a hydraulic pressure powered drive piston (46) slidably disposed in a drive cylinder (45), wherein the hydraulic pressure powered drive piston (46) is coupled to the pump piston (62) for driving the pump piston (62).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a two-stroke compression ignition internal combustion engine fuel or lubrication pump,

The present disclosure relates to a fuel or lubrication pump for a large low speed two stroke uniflow compression ignition internal combustion engine.

Large two-stroke turbocharged compression ignition internal combustion crosshead engine (engine) is commonly used as a propulsion system for large ships or as a prime mover for power plants. With enormous size, weight and power output, this engine is very different from a conventional combustion engine, and a large two-stroke turbocharged compression internal combustion engine is itself categorized as one class.

Large two stroke compression ignition internal combustion engines are traditionally operated with liquid fuels such as fuel oil or heavy oil. However, as interest in the environment increases, alternative fuels such as gas, methanol, coal slurry, and petroleum coke are being developed.

Some of these alternative fuel types are difficult to handle with conventional fuel pumps. Some are abrasive like coal slurries, some have poor lubrication properties like gasoline, others require cryogenic temperatures like liquefied gas.

WO 2016/015732 discloses a cylinder lubrication system with a plurality of cylinder oil pumps. Each cylinder oil pump is provided with a drive piston connected to a plurality of dosing plungers.

Therefore, there is a need to provide a pump capable of handling such alternative fuels.

In view of this background, an object of the present invention is to provide a pump that overcomes or at least reduces the above-mentioned problems.

The above and other objects are achieved by the features of the independent claim. Additional implementations are evident from the dependent claims and the detailed description and drawings.

According to a first aspect, there is provided a pump including two or more pump sections, each pump section including a pump piston slidably disposed in the pump cylinder, and a hydraulically powered drive piston slidably disposed in the drive cylinder, The drive piston is coupled to the pump piston for driving the pump piston.

By providing a pump in which each pump piston is operated by a linear hydraulic actuator, any suitable pump piston can be driven in a fully flexible manner independent of the limitations and inertia of the crankshaft, Lt; / RTI >

According to a first possible embodiment of the first aspect, the pump further comprises at least one hydraulic control valve connected to the tank and a high-pressure hydraulic fluid supply for controlling the flow of hydraulic fluid to / from the drive cylinder of the one or more pump sections, , The high-pressure hydraulic fluid supply is preferably a variable and controllable source of pressure.

According to a second possible embodiment of the first aspect, the drive cylinder comprises a drive chamber and a return chamber.

According to a possible third embodiment of the first aspect, the drive chamber is connected to a hydraulic control valve and the return chamber is connected permanently to the hydraulic oil supply at a pressure lower than the pressure of the high-pressure hydraulic oil supply.

According to a possible fourth embodiment of the first aspect, the drive cylinder is provided with a position sensor for sensing the position of the drive piston in the associated drive cylinder.

According to a fifth possible embodiment of the first aspect, the fuel supply system further comprises an electronic control device for receiving a signal from the position sensor, and at least one said hydraulic control valve is connected to an electronic control valve to be.

According to a sixth possible embodiment of the first aspect, the electronic control device is configured to selectively connect the drive chamber of the pump section to a high pressure hydraulic fluid supply or tank.

According to a possible seventh embodiment of the first aspect, the electronic control device is configured to start the pump stroke of the other drive piston when the pump stroke of the drive piston is close to its end, There will be overlap. Thus, a substantially stable flow can be achieved without significant pressure fluctuations for the fuel or lubricant leaving the pump.

According to a possible eighth embodiment of the first aspect, the electronic control device is configured to take into account the dynamics of the end pump run and the dynamics of the start pump run to obtain a substantially constant flow for high pressure fuel or lubricant from the pump.

According to a possible ninth embodiment of the first aspect, the electronic control unit is configured to determine when to start the pump stroke of one of the drive cylinders / units and to determine when the pump stroke of the drive cylinder should end. Therefore, it is possible to accurately control the point at which the pump stroke starts, and in particular, the point at which the pump stroke ends.

According to a possible tenth embodiment of the first aspect, the electronic control unit is configured to operate each drive cylinder substantially continuously, preferably in a less overlapping manner.

According to a possible eleventh embodiment of the first aspect, the electronic control apparatus is configured so that the drive piston of the other pump section operates when one of the pump sections fails. This allows redundancy to occur and pump operation can continue even if one of the pump parts fails.

According to a possible twelfth embodiment of the first aspect, the electronic control device is configured to actuate a drive piston of another pump section which functions to actuate the drive cylinder of the other pump section to function substantially continuously, preferably in a small overlap.

 According to a possible thirteenth embodiment of the first aspect, the electronic control device is arranged to adjust the position of the drive piston in which the drive chamber is separated from the high-pressure hydraulic fluid supply in relation to the magnitude of the liquefied gas flow from the high- pressure pump to the high-pressure vaporizer. Thus, the position at which the pump stroke reverses can be maintained the same regardless of the speed of the pump piston and the drive piston and the resulting inertia.

According to a possible fourteenth embodiment of the first aspect, the electronic control device is characterized in that the drive chamber of the associated drive piston is disconnected from the supply of high-pressure fluid in a direction opposite to the drive stroke direction when the flow of fuel or lubricant from the pump increases, To adjust the position of the piston.

According to a fifteenth possible embodiment of the first aspect, the electronic control device comprises a drive piston in which the drive chamber of the associated drive piston is disconnected from the source of high-pressure fluid in the direction of the drive stroke direction when the flow of fuel or lubricant from the pump is reduced, As shown in FIG.

According to a possible sixteenth embodiment of the first aspect, the electronic control device is adapted to control the pump piston in accordance with an algorithm or a plan, or optionally, in relation to the pump piston in order to distribute the reversing position of the pump piston in the stroke region of the pump piston, The drive chamber of the drive piston is configured to adjust the position of the drive piston separated from the high pressure hydraulic fluid supply.

According to a possible seventeenth embodiment of the first aspect, the electronic control device is configured to control the pressure pumped fuel or lubricant delivered by the pump by controlling the pressure of the hydraulic fluid supplied to the drive chamber. Thus, an effective and immediately responsive control over the pressure of the pumped fuel or lubricant is achieved.

According to a possible eighteenth embodiment of the first aspect, the electronic control device is configured to use a desired pressure for the fuel or lubricant pumped by the feed-forward function to control the pressure of the hydraulic fluid supplied to the drive chamber. By using the feed-forward control of the liquefied gas pressure through the hydraulic pressure, the pressure of the pumped fuel or lubricant can be controlled much more quickly and stably.

According to a possible nineteenth embodiment of the first aspect, the electronic control device is configured to use the measured pressure for the fuel or lubricant pumped with the feed-back function to control the pressure of the hydraulic fluid supplied to the drive chamber. Thus, nonlinearity and transient phenomena can be accommodated by the control system.

According to a possible twentieth embodiment of the first aspect, the electronic control device is configured to control the operation and stop of each drive piston independently of controlling the pressure of the hydraulic fluid supplied to the drive chamber. Therefore, the control strategy for the actuation of the drive piston can be optimized by the electronic control unit independently of the pressure control.

In a possible twenty-first embodiment of the first aspect, the control device is configured to use a signal indicative of the position of the drive piston to control actuation and stop of the drive piston.

According to a second aspect, there is provided a large two-stroke turbocharged compression ignition internal combustion engine according to the first aspect and any possible implementation thereof.

According to a third aspect, there is provided a cargo ship comprising an engine according to the second aspect.

According to a fourth aspect, there is provided a method of pumping fuel or lubricating oil to an internal combustion engine to inject high pressure gas into the engine, the method comprising: storing fuel or lubricating oil in a storage tank; And pumping fuel or lubricating oil to the engine, wherein the pump comprises two or more pump sections, each pump section having a drive piston coupled to the pump piston for driving the pump piston, And a hydraulic power drive piston slidably disposed within the drive cylinder, the method comprising: supplying high-pressure hydraulic fluid to the drive cylinder to drive the drive piston; And controlling the pressure of the fuel or lubricant leaving the high-pressure pump by controlling the pressure of the hydraulic oil supplied to the drive cylinder.

According to a first possible embodiment of the fourth aspect, the method further comprises the step of actuating one of the drive pistons during a drive stroke and then stopping the drive piston during a return stroke.

According to a second possible embodiment of the fourth aspect, the pump piston and the drive piston are connected together and move in unison.

According to a possible third embodiment of the fourth aspect, the method is arranged to start the pump stroke of the other drive piston when the pump stroke of the drive piston is close to its end, so that a small overlap between the end pump stroke and the start pump stroke And a step to be performed.

According to a fourth embodiment of the fourth aspect, the method further includes taking into account the dynamics of the end pump run and the dynamics of the start pump run to obtain a substantially constant flow for the fuel or lubricant from the pump to the engine do.

According to a possible fifth implementation of the fourth aspect, the method further comprises causing each drive cylinder to operate in a substantially continuous, preferably less overlapping manner.

These and other aspects of the invention will become apparent from the embodiments described below.

According to the present invention, there is an effect of providing a fuel or lubrication pump that overcomes or at least reduces the above-mentioned problems.

1 is a front elevational view of a large two-stroke diesel engine according to an embodiment of the present invention.
Figure 2 is a schematic representation of a fuel supply system for supplying high pressure natural gas from a LNG storage tank to a large two-stroke diesel engine according to Figure 1;
3 is an elevational view of the high pressure pump of the fuel supply system of Fig. 2; Fig.
Figure 4 is a schematic representation of the high pressure pump of Figure 3;
5 is a detailed sectional view of the pump section of the high-pressure pump of FIG.
6 to 8 are graphs showing the operation of the high pressure pump of FIG. 3;
Figure 9 is a schematic representation of a control system for controlling the high pressure pump of Figure 3;
10 and 11 are graphs showing the piston motion of the high pressure pump of FIG.

In the following detailed description, a fuel supply system for a large two-stroke low-speed turbocharged compression ignition internal combustion engine including a crosshead will be described with reference to exemplary embodiments, but the internal combustion engine may be a two- Or diesel, and it should be understood that turbocharging and exhaust gas recirculation may or may not be present. Further, the pump for supplying the fuel or the lubricant to the large two-stroke low-speed turbocharged compression ignition internal combustion engine including the crosshead will be described with reference to the exemplary embodiments. However, the internal combustion engine is not limited to the two- It may be of other types, such as auto or diesel, and it should be understood that turbocharging and exhaust gas recirculation may or may not be present.

Figure 1 shows a large low speed turbocharged two stroke diesel engine with a turning wheel and a crosshead. In this exemplary embodiment, the engine has six cylinders in a row. A large low speed turbocharged two stroke diesel engine is typically supported by a cylinder frame supported by an engine frame 6 and has four to fourteen cylinders in heat. The engine can be used, for example, as a main engine of a ship or as a stationary engine that operates a generator of a power plant. The total output of the engine may range, for example, from 1,000 to 110,000 kW.

The engine is a two-stroke, single-flow compression ignition engine in which, in this example embodiment, the engine 1 is provided with a scavenge port in the lower region thereof and an exhaust valve 4 at the center of the cylinder liner 1. The scavenge passes from the scavenging accommodating portion 2 to the scavenging port of the individual cylinder 1. The piston in the liner of the cylinder 1 compresses the air and the high-pressure fuel such as the gaseous fuel is injected through the fuel injection valve of the cylinder cover, the combustion proceeds and the exhaust gas is generated.

When the exhaust valve 4 is opened, the exhaust gas flows to the exhaust gas receiving portion 3 through the exhaust duct coupled with the cylinder 1 and then flows to the turbine of the turbocharger 5, The gas is discharged to the atmosphere through an exhaust conduit. The turbine 6 of the turbocharger 5 drives a compressor through which fresh air is supplied via an intake port. The compressor conveys pressurized scrap to a scavenging duct leading to the scavenging receptacle. The scavenge in the scavenging duct passes through the intercooler 7 for desired cooling.

2 is a schematic diagram of a fuel or lubricating oil supply system for an engine. The fuel supply system may be installed in a marine vessel such as an LNG carrier or a container ship.

The fuel supply system includes a fuel storage tank 8 in which fuel such as lubricating oil or fuel oil is stored. Further, the fuel is a liquefied gas stored under a cryogenic condition.

The feed conduit (9) connects the outlet of the fuel or lubricant storage tank (8) to the inlet of the high pressure pump (40). The feed pump 10 supports the transport of fuel or lubricant from the storage tank 8 to the inlet of the high-pressure pump 40.

The pump (40) pumps fuel or lubricant gas through the supply conduit (18) to the engine. The valve device 19 controls the connection of the fuel / lubricant supply system and the large two-stroke diesel engine.

The pump 40 is provided with two or more pump units 41, 42 and 43 (three pump units are shown in this embodiment). Each of the pump sections 41, 42 and 43 connects the drive piston 46 to the pump piston 62 to drive the pump piston 62 and the pump piston 62 slidably disposed in the pump cylinder 61, And a hydraulic power drive piston (62) slidably disposed in the drive cylinder (45).

The pump piston (62) and the pump cylinder (61) form a positive displacement pump. In one embodiment, the pump piston 62 and the pump cylinder 61 together with the pump chamber 63 form a so-called low temperature end of the cryogenic pump section for pumping liquefied gas.

The pump cylinder 61 is connected to the drive piston of the pump section 41, 42, 43 via the piston rod 49. The drive piston 46 divides the interior of the drive cylinder 45 into a drive chamber 48 and a return chamber 47.

The drive cylinder (45) is connected to the source of the high-pressure hydraulic actuator (20). Via a high-pressure hydraulic fluid supply conduit 23, for example to a pump or pump station. In the illustrated embodiment, the high pressure hydraulic fluid supply 20 includes an electric drive motor 21 for driving the high pressure pump 22. The high-pressure pump 22 may be, for example, a positive displacement pump, preferably a variable displacement pump. For redundancy purposes, the high-pressure hydraulic fluid supply 20 includes two high-pressure hydraulic pumps 22, each driven by its own electric drive motor 21 in the embodiment.

3 is a diagram showing a state in which the high pressure pump 40 having three pump sections 41, 42 and 43 provided with a pump cylinder 61, a drive cylinder 45 and a control valve 24 is lifted. The pump portions 41, 42 and 43 are supported by the frame 35 together with an accumulator 53 for equalizing the upper pressure of the high-pressure pump 40 and equalizing the lower pressure of the return chamber. Since the pump sections 41, 42 and 43 are arranged in a compact manner on the frame 35 and there is no spark on the frame 35 and only ATEX approved electrical components are present in the ATEX environment, Can be installed.

4 is a schematic representation of a high-pressure pump 40 with pump sections 41, 42 and 43. FIG. Each of the pump sections 41, 42 and 43 is connected to the tank via the hydraulic liquid return line 26 and connected to the pump sections 41, 42 and 43 via the hydraulic liquid supply conduit 23, And is connected to a source of high-pressure hydraulic fluid including a positive displacement pump (22). Each pump section 41, 42, 43 is connected to a supply conduit 18.

Each pump section 41, 42, 43 includes a hydraulic control valve 24 configured to selectively connect each drive chamber 48 to a source of high-pressure hydraulic fluid or a tank via a control conduit 25.

Each of the pump sections 41, 42 and 43 includes a drive unit 44 in the form of a linear hydraulic actuator formed by a drive cylinder 45 in which a drive piston 46 is slidably disposed. The return chamber 47 preferably includes a flow restriction 33 and is connected to the accumulator 32 via a return chamber supply line to ensure a stable supply of hydraulic fluid pressurized into the return chamber 47. [ And is permanently connected to a hydraulic source including a hydraulic pump 30, e.g., a variable displacement pump. Alternatively, the low pressure source is obtained from the high pressure hydraulic system via a pressure reducing valve. In one embodiment, the supply pressure of the hydraulic fluid to the return chamber 47 is significantly lower than the pressure of the hydraulic fluid supplied to the drive chamber 48. Alternatively, the effective pressure surface of the side of the drive piston 46 facing the return chamber 47 may be arranged to be significantly smaller than the effective pressure surface of the drive piston facing the drive chamber 48. In the latter case, the pressure of the hydraulic oil in the return chamber 47 may be substantially the same as the supply pressure of the hydraulic oil to the drive chamber 48.

Each pump section 41,42,43 includes a pump 60 in the form of a linear positive displacement pump formed by a pump cylinder 61 and includes a pump piston 62 to form a pump chamber 63 within the pump cylinder. Lt; / RTI > The pump chamber 63 is connected to the feed conduit 9 via a first one-way valve 51 that allows only flow to the pressure chamber. The pump chamber 63 is connected to the supply conduit 18 via a second one-way valve 52 which allows only flow from the pressure chamber.

5 is a detailed sectional view of pump sections 41, 42 and 43 of the high-pressure pump 40. As shown in Fig. The pump sections 41, 42 and 43 include a hydraulic linear actuator 44 including a cylinder 45 in which a drive piston 46 is disposed. The drive piston 46 is connected to the piston shaft 47 and is preferably formed as one device with the piston shaft 47. The piston rod 49 and the drive piston 46 are provided with a bore 58 for receiving the rod 57 of the position sensor 56. The signal of the position sensor 56 is transmitted to the electronic control device 70. The drive piston 46 divides the interior of the drive cylinder 45 into a drive chamber 48 and a return chamber 47. In Fig. 5, the return chamber 47 is not recognizable because the drive piston 46 has reached the end of the drive stroke. The drive chamber 48 is connected to the hydraulic control valve 24 via a bore 25. The return chamber 47 is permanently connected to the hydraulic source through the bore 31. [

The piston rod 47 of the linear hydraulic actuator 44 is connected to the piston rod 62 of the cryogenic pump 60 (although the pump 60 is a conventional linear positive displacement pump for pumping non- Although it may be good). The connection of the piston rod 49 and the pump piston 62 is set by the connector piece 54 in such a manner that the piston rod 49 and the pump piston 62 move in unison. The drive cylinder 45 is connected to the pump cylinder 61 by a bolt connection 55. The pump (60) is provided with an outlet connecting the pump chamber (63) to the transfer conduit (50).

9 is a graphical representation of a control system in the form of an electronic control device 70 for controlling the operation of the high-pressure pump 40. Fig.

The electronic control unit 70 receives the lubricant pressure set point 71 fuel. The pressure set point 71 is transferred to the first summing point 72. At the first summing point 72 the measured gas pressure is subtracted and the difference in gas pressure measured at the pressure set point 71 and the outlet of the pump 40 is transmitted to the PI controller 74 which is part of the feedback control loop do. The pressure set point 71 is communicated to the feed-forward piston ratio gain device 78. The signal from the feed-forward piston ratio gain device 78 is compared to the signal from the PI controller 74 at the second summation point 76.

The gas pressure measured for the fuel or lubricating oil supplied to the first summing point 72 may be based on the measurement of the pipe volume in the engine, i.e. the pressure downstream of the valve arrangement 19. [ The valve arrangement 19 is a double block and bleed valve arrangement which receives the flow of fuel or lubricant from the supply conduit 18. The measured pressure of the fuel or lubricant is filtered in a filter (86).

The result of the comparison at the second summation point 76 is conveyed to the high-pressure hydraulic actuator 20. Based on this signal, the high-pressure hydraulic fluid supply 20 delivers the correct hydraulic fluid pressure to the high-pressure pumping section 40.

The electronic control device 70 receives a signal indicative of the position of the drive piston 46 and processes the position signal in the piston monitoring device 92. The piston monitoring device 92 is connected to the piston operating strategy device 90. Details of the operation of the piston monitoring device 92 and the piston operating strategy device 90 are described in more detail below. The signal of the piston actuating strategy device 90 is transmitted to the control valve 24 of the high pressure pump 40 to actuate the drive piston 46.

The actuation of the drive piston 46 causes fuel or lubricant to be pumped through the supply conduit 18.

The main pressure control of the electronic control device 70 is feed-forward. The PI (proportional integral) controller compensates for nonlinearities and supports transient phenomena.

The pressure of the fuel or the lubricating oil is controlled by itself by setting the hydraulic pressure supply pressure to the pump sections (41, 42, 43). The pressure control is on the hydraulic side and does not need to operate on the gas side. This system makes it impossible for the fuel or lubricant to reach too high a pressure when the hydraulic pressure is properly controlled.

The drive piston 46 is controlled through a control strategy that is not part of the actuation of the pressure control.

Each of the pump units 41, 42, and 43 is individually controllable. Thus, various piston strategies and various operating conditions can be implemented. Further, since it is possible to change the pump sections 41, 42, 43 from three to two between the two strokes, it is possible to execute the pump sections 41, 42, 43 individually, thereby providing redundancy.

The return speed can be greater than the forward (pump) speed, so overlapping is possible when operating with only two pump sections. The overlap between the pump sections 41, 42, 43 can be adjusted as needed to reduce pressure spikes.

The end position of the pump stroke can be varied over time to disperse the wear in the region of the pump cylinder 61, which is in contrast to the higher wear in the fixed position on the cylinder.

There is little or no pressure overshoot in the sudden shutdown (piston stop) due to very low inertia and other factors that adversely affect the dynamic response.

The control valve 24 may be a hydraulic control valve or an electronic control valve. In this embodiment, the control valve 24 is a hydraulic control valve and is provided with an electronic control solenoid valve (not shown) for controlling the hydraulic control signal to the control valve 24. [ The electronic control solenoid valve receives an electronic control signal from the electronic control unit 70.

The electronic control unit 70 is configured to selectively connect the drive chambers 48 of the pump units 41, 42 and 43 to the high-pressure hydraulic oil supply source 20 or the tank.

The electronic control device 70 is configured to start the pump stroke of the drive piston when the pump stroke of the other drive piston 47 approaches its end so that there is a small overlap between the end pump stroke and the start pump stroke. In one embodiment, the electronic control unit 70 is configured to operate each drive cylinder substantially continuously, preferably with less overlap.

Thus, without significant pressure fluctuations, a substantially stable LNG flow can be achieved with a pressure vaporizer, as shown in Figures 6 and 7. [

6, 7 and 8 illustrate exemplary operation of the high-pressure pump 40. As shown in Fig. A thick continuous line indicates the pump section 42, and a dotted line indicates the pump section 43. [0034] Fig. 6 is a graph showing the movement of the drive piston 46 / pump piston 62. Fig. As can be seen from the graph, the pump stroke start of the next pump section starts just before the pump stroke of the currently operating pump section. Figure 7 shows the resulting pressure consisting of the pressure output from the transfer conduit 50 of the three pump parts 41, 42, 43. The resulting pressure is virtually constant and unchanged.

Figure 8 shows the velocity profile of the pump section which clearly shows that the speed of the return stroke is significantly higher than the speed of the pump stroke so that only two of the three or more pump sections are allowed to overlap between the pump sections .

In one embodiment, the electronic control device 70 is configured to provide the kinetic of the shutdown pump stroke to obtain a substantially constant flow of high pressure liquefied gas from the high pressure pump to the high pressure vaporizer 14, Is configured to take into account the dynamics of the starting pump stroke.

In one embodiment, the electronic control unit 70 determines when the pump stroke of one of the pump units 41, 42, 43 should start and when the pump stroke of any of the drive units 41, 42, To be determined. Thus, the point at which the pump stroke starts and in particular the point at which the pump stroke ends can be accurately controlled with the piston strategy device 90, preferably with the piston monitoring device 92.

In one embodiment, the electronic control unit 70 is configured to operate a drive piston of another pump section that functions if one of the pump sections 41, 42, 43 fails. As a result, redundancy is achieved, so that pump operation can be continued even if one of the pump units 41, 42, 43 fails.

In one embodiment, the electronic control unit 70 includes a drive piston 46 that is separate from the high-pressure hydraulic fluid supply 20 with respect to the magnitude of the liquefied gas flow from the high-pressure pump 40 to the high-pressure vaporizer. As shown in FIG. The position at which the pump stroke is reversed can be controlled regardless of the speed and the resulting inertia of the drive piston 46 and the pump piston 62. [

According to one embodiment, the electronic control unit 70 controls the drive of the associated drive piston 46 from the high-pressure hydraulic fluid supply 20 in a direction opposite to the drive stroke direction when the flow of fuel or lubricant from the high- (48) is arranged to adjust the position of the disengaging drive piston (46), and the electronic control device (70) is configured to adjust the position of the high pressure hydraulic oil supply source 20 to the position of the drive piston 46 from which the drive chamber 48 of the associated drive piston 46 is disengaged. This is shown in FIGS. 10 and 11. FIG.

10 shows the effect of the increased speed of drive piston 46 and pump piston 62 on the end position of the drive / pump stroke. A thick continuous line indicates the pump section 42, and a dotted line indicates the pump section 43. [0034] The electronic control unit 70 controls the hydraulic control valve 24 (not shown) to connect the drive chamber 48 to the tank when the drive piston reaches 80 mm stroke, regardless of the load / size of the liquefied gas flow delivered by the high- Lt; / RTI > Because of inertia and high speed, the stop / retract position of the drive piston 46 varies from 85 mm of the 25% load to 89 mm of the 50% load and 98 mm of the 100% load.

11 shows an electronic control device (not shown) that corrects the increased speed of the drive piston 46 / pump piston 62 by connecting the drive chamber 48 to the tank in a short stroke when the load is high and a long stroke when the load is low 70). ≪ / RTI > As can be seen from the graph, the electronic control unit 70 can accurately control the end position of the drive / pump stroke in this manner.

In the example of the graph above, the signal for connecting the drive chamber 48 to the tank for a 25% load of the next drive cylinder (i.e. 25% of the maximum capacity of the high pressure pump 40) When it comes out. The drive chamber of the "previous" drive cylinder is connected to the tank when it is 93 mm into the drive chamber. The connection of the high pressure source of the next drive cylinder "signal on" and the tank connection of the "previous" cylinder "signal off" are shown in Table 1 below.

25% load 45% load 70% load 100% load Signal on 75 mm 75 mm 75 mm 75 mm Signal Off 93 mm 86 mm 83 mm 80 mm Stop position 97 mm 97 mm 97 mm 97 mm

It is, of course, still possible to program the electronic control unit 72 intentionally to change its starting position in order to reduce the wear of the pump cylinder 61.

The electronic control device 70 may be used in accordance with an algorithm or scheme to distribute the position in which the pump piston 62 is reversed in the stroke region of the pump piston 62 to reduce wear of the pump cylinder 61, The drive chamber 48 of the piston 46 is configured to adjust the position of the drive piston 46 separated from the high pressure hydraulic oil supply 20. It is known that the wear of the pump cylinder 61 is highest at the position where the pump stroke ends. By changing the position at which the pump stroke is terminated, the wear of the pump cylinder 61 is dispersed to a larger area, so that the service life of the pump cylinder 61 can be considerably increased.

In one embodiment, the electronic control unit 70 is configured to control the actuation and stop of each drive piston 46 independently of controlling the pressure of the hydraulic fluid supplied to the drive chamber 48. Thus, the control strategy for the actuation of the drive piston 46 can be optimized by the electronic control unit 70 independently of the pressure control.

The invention has been described in conjunction with various embodiments thereof. However, other modifications to the disclosed embodiments can be understood and effected by those skilled in the art, practicing the claimed invention, from the study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and "one" or "one" The electronic control device may be formed by a combination of separate electronic control devices. The mere fact that certain measures are quoted in different dependent claims does not indicate that a combination of these used in the solution can not be used to advantage. Reference signs used in the claims should not be construed as limiting the scope.

8 Fuel storage tank 14 High pressure carburetor
24 control valve 40 high pressure pump
45 drive cylinder 46 drive piston
47 Return Chamber 48 Drive Chamber
62 Pump piston 70 Electronic control unit

Claims (26)

A cryogenic pump (40) for pumping cryogenic fuel, wherein the pump (40) comprises two or more pump sections (41, 42, 43), each of the pump sections A drive piston 46 is coupled to the pump piston 62 for driving the pump piston 62 and is slidable within the drive piston 45 and the pump piston 62 slidably disposed within the pump cylinder 61. [ Wherein said drive piston (46) is hydraulically powered. The method according to claim 1,
Pressure hydraulic fluid supply source 20 and at least one control valve 24 connected to the tank to control the flow of hydraulic fluid to / from the drive cylinder 45 of the pump section 41, 42, Wherein the high-pressure hydraulic fluid supply (20) is a source of pressure, preferably a variable and controllable source. The method according to claim 1 or 2,
Characterized in that the drive cylinder (45) comprises a drive chamber (48) and a return chamber (47). The method of claim 3,
The drive chamber 48 is connected to the control valve 24 and the return chamber 47 is preferably connected to a hydraulic oil supply 30 at a pressure lower than the pressure of the high pressure hydraulic oil supply 20 Features cryogenic pumps. The method according to any one of claims 1 to 4,
Characterized in that the drive cylinder (45) is provided with a position sensor (56) for sensing the position of the drive piston (46) in the associated drive cylinder (45). The method of claim 5,
Further comprising an electronic control device (70) that receives a signal from the position sensor (56), wherein at least one of the control valve (24) is an electronic control valve coupled to the electronic control device Pump. The method of claim 6,
Characterized in that the at least one electronic control device (70) is configured to selectively connect the drive chamber (48) of the pump section (41, 42, 43) to the high pressure hydraulic fluid supply source Pump. The method according to claim 6 or 7,
The electronic control device 70 is configured to initiate a pump stroke of the other drive piston 46 when the pump stroke of the drive piston 46 is close to its end so that there is a small overlap between the end pump stroke and the start pump stroke Wherein the cryogenic pump is a cryogenic pump. The method of claim 8,
Characterized in that the electronic control device (70) is configured to take into account the dynamics of the end pump run and the dynamics of the start pump run to obtain a substantially constant flow for the high-pressure fuel or lubricant from the pump (40). The method of claim 9,
Characterized in that the electronic control unit (70) is configured to operate each of the drive cylinders (45) substantially continuously, preferably in a superimposed manner. 11. The method according to any one of claims 6 to 10,
The electronic control unit 70 is configured to control the drive piston 46 in which the drive chamber 48 is disconnected from the high pressure hydraulic fluid supply 20 with respect to an increase in fuel or lubricant flow size pumped by the pump 40. [ Is configured to adjust the position of the cryogenic pump. The method of claim 11,
The electronic control unit 70 controls the drive of the associated drive piston 46 from the high-pressure hydraulic fluid supply source 20 in the direction opposite to the drive stroke direction when the flow of fuel or lubricant pumped by the pump 40 increases. Is configured to adjust the position of the drive piston (46) from which the chamber (48) is disengaged. The method according to claim 11 or 12,
Pressure hydraulic fluid supply source (20) in the direction of the drive stroke direction when the flow of fuel or lubricant pumped by the pump (40) is reduced, the electronic control device (70) Is configured to adjust the position of the drive piston (46) from which the piston (48) is disengaged. The method according to any one of claims 6 to 13,
The electronic control unit 70 may be operated in accordance with an algorithm or plan or arbitrarily driven to distribute a position where the pump piston 62 reverses part of the stroke of the pump piston 62 for the purpose of reducing wear of the pump cylinder 61. [ Is configured to adjust the position of the piston (46). The method according to any one of claims 6 to 14,
Wherein the electronic control device (70) is configured to control the pressure of fuel or lubricant leaving the pump by controlling the pressure of the hydraulic oil supplied to the drive chamber (48). 16. The method of claim 15,
Wherein the electronic control device (70) is configured to use a desired pressure of fuel or lubricant to leave the pump in a feed-forward function for controlling the pressure of the hydraulic fluid supplied to the drive chamber (48). The method according to claim 15 or 16,
Wherein the electronic control device (70) is configured to use the measured pressure of fuel or lubricant leaving the pump as a feedback function to control the pressure of the hydraulic fluid supplied to the drive chamber (48). The method according to any one of claims 15 to 17,
Wherein the electronic control device (70) is configured to control the operation and stop of each drive piston (46) regardless of the pressure of the hydraulic fluid supplied to the drive chamber (48). The method according to any one of claims 15 to 18,
Characterized in that the electronic control device (70) is configured to use a signal indicative of the position of the drive piston (46) to control activation and deactivation of the drive piston (46). Characterized in that it comprises a cryogenic pump (40) according to any one of claims 1 to 19 for supplying fuel or lubricating oil to the engine. A method for controlling pump piston operation of a pump (40)
The pump 40 includes two or more individually actuated pump portions 41, 42 and 43 and each of the pump portions 41, 42 and 43 includes a drive piston (46) is coupled to the pump piston (62) and is slidably disposed within the pump cylinder (61) and the drive piston (62) which is hydraulically powered and slidably disposed within the drive cylinder ),
The method comprises:
Operating the drive piston (46) during a drive stroke and then stopping the drive piston (46) during a return stroke;
Measuring the position of the drive piston (46) during a drive stroke; And
Characterized in that the drive piston (46) is actuated when the drive piston (46) is in the return position and the drive piston (46) is stopped in a position dependent on the speed of the drive piston Lt; / RTI > 23. The method of claim 21,
The drive piston 46 is stopped at a position closer to the return position as the speed of the drive piston 46 increases during the drive stroke and the drive piston 46 is stopped during a drive stroke of the drive piston 46 And stops at a further distance from the return position as the speed decreases. The method of claim 21 or 22,
Characterized in that the drive piston (46) is operated substantially sequentially and the operation of the next drive piston (46) occurs preferably immediately before the stop of the currently operating drive piston (46). The method of any one of claims 21 to 23,
Pressure hydraulic fluid to the drive piston 46. The pressure of the fuel or lubricant that leaves the pump 40 is controlled by controlling the pressure of the hydraulic fluid supplied to the drive piston 46 Lt; / RTI > A method for controlling pump piston operation of a pump (40)
The pump 40 includes two or more individually actuated pump portions 41, 42 and 43 and each of the pump portions 41, 42 and 43 includes a drive piston (46) is coupled to the pump piston (62) and is slidably disposed within the pump cylinder (61) and the drive piston (62) which is hydraulically powered and slidably disposed within the drive cylinder ),
The method comprises:
Operating the drive piston (46) during a drive stroke and then stopping the drive piston (46) during a return stroke;
Supplying high-pressure hydraulic fluid to the drive piston (46); And
And controlling the pressure of the fluid leaving the pump (40) by controlling the pressure of the hydraulic fluid supplied to the drive piston (46). 26. The method of claim 25,
Characterized in that the drive piston (46) is operated substantially sequentially and the operation of the next drive piston (46) occurs preferably immediately before the stop of the currently operating drive piston (46).

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