Fuel injector for an internal combustion piston engine

Abstract

The present invention relates to a fuel injector (10) for an internal combustion piston engine, comprising: a hydraulic amplifier (20) for pressurizing fuel to an injection pressure and disposed in an injector body assembly (102); and an injection valve assembly (30) disposed in the injector body assembly (102) and configured to supply fuel pressurized by the hydraulic amplifier (20) to a combustion chamber (104) of the engine, wherein the hydraulic amplifier (20) comprises: a cylinder (202); and an operating piston (204) disposed in the cylinder, the operating piston (204) partially defining a working space (208) in the cylinder such that when the operating piston moves along a first direction... The volume of the working space increases during operation; a control fluid conduit (206) is arranged in the injector body assembly (102) and leads into the working space (208); and a pneumatic spring assembly (210) includes a gas compression space (212) partially defined by an operating piston (204) in the cylinder (202) such that the volume of the gas compression space (212) decreases when the operating piston moves in a first direction, and the pneumatic spring assembly (210) is arranged to apply force to the operating piston (204) in a second direction opposite to the first direction to assist the operating piston (204) in returning to its initial position.

Description

Technical Field

[0001] The present invention relates to a fuel injector for an internal combustion piston engine as described in the preamble of independent claim 1. Background Technology

[0002] Large two-stroke internal combustion engines are commonly used as prime movers in large ocean-going vessels. Two-stroke engines can burn different types of fuel, thus reducing the ship's operating costs. Two-stroke engines have relatively high thermal and engine efficiency. They are also very reliable in operation. Because two-stroke engines are low-speed engines, they do not require reduction gears or reduction devices for propulsion like high-speed four-stroke engines. Traditionally, large two-stroke engines mostly operate on heavy fuel oil.

[0003] There is a growing focus on reducing emissions of carbon dioxide, nitrogen oxides, and sulfur from internal combustion engines, leading to a desire for alternatives to traditional fuels and improved combustion control. Decarbonization, in particular, is a key concern. One effective solution for reducing emissions and operating costs from large internal combustion engines (whether in ships or power plants) is the so-called dual-fuel or even tri-fuel engine, which can use fuels that are carbon-free or contain less carbon than traditionally used fossil fuels. These fuels are often referred to as alternative fuels. The properties of these alternative fuels differ significantly from traditional fuels such as heavy fuel oil, light fuel oil, or other natural crude oil-based fuels. For example, these fuels have relatively poor lubrication properties, which must be considered in the clearances between moving parts in the fuel injection system. Furthermore, as low-flash-point fuels, they pose serious safety risks. Therefore, there is a need to develop fuel injectors suitable for these fuels.

[0004] Typically, hydraulic amplifiers used to increase fuel pressure in conjunction with fuel injectors employ double-acting hydraulic piston operation, where piston movement is controlled by alternately supplying pressurized control fluid to opposite sides of the operating piston. This requires a fairly complex hydraulic system.

[0005] The purpose of this invention is to provide a fuel injector for an internal combustion piston engine that is reliable and simple in structure. Summary of the Invention

[0006] The objectives of the invention are achieved substantially as set forth in the independent claims and as disclosed in the other claims which describe further details of different embodiments of the invention.

[0007] According to the present invention, a fuel injector for an internal combustion piston engine comprises: - A hydraulic amplifier, which is used to pressurize the fuel to the injection pressure, and is arranged in the injector body assembly; - An injection valve assembly disposed within the injector body assembly and configured to supply fuel pressurized by a hydraulic amplifier to the combustion chamber of the engine, wherein the hydraulic amplifier includes: - Cylinder; and - An operating piston arranged in a cylinder, which partially defines the working space in the cylinder such that the volume of the working space increases when the operating piston moves in a first direction; - A control fluid conduit disposed in the injector body assembly, the control fluid conduit leading into the working space; and - A pneumatic spring assembly including a gas compression space partially defined by an operating piston in a cylinder, such that the volume of the gas compression space decreases as the operating piston moves in a first direction, and the pneumatic spring assembly is arranged to apply a force to the operating piston in a second direction opposite to the first direction to assist the operating piston in returning to its initial position.

[0008] The fuel injector according to the present invention provides reliable fuel injection and can be reliably controlled. It is also robust in structure and suitable for long-term use.

[0009] According to one aspect of the invention, a fuel injector includes a control fluid flow control device configured to either introduce pressurized control fluid into a working space of a cylinder located at one end of an actuating piston, thereby causing the actuating piston to move in a first direction resulting in amplification, or release the pressure of the control fluid in the working space of the cylinder, thereby allowing the actuating piston to return to its initial position. Thus, the fuel injector can be operated hydraulically in a single-acting manner, with a simple structure, while still providing adequate controllability for fuel injection.

[0010] According to one aspect of the invention, a gas conduit is provided, which is arranged in the injector body assembly and leads to a gas compression space. This allows the gas compression space to be connected to a pressurized gas source to pressurize the pneumatic spring assembly and provide a reliable and rapid return stroke for the operating piston.

[0011] According to one aspect of the invention, the gas conduit includes a gas flow restriction system that provides gas flow resistance in both directions, such that the flow resistance toward the gas compression space is less than the flow resistance from the gas compression space. Thus, during or immediately after the return motion of the operating piston to its initial position, the gas compression space can be pressurized and maintained at a desired pressure.

[0012] According to one aspect of the invention, the gas conduit includes a one-way valve that allows gas to flow only in the direction toward the gas compression space. The one-way valve enables a large flow of gas toward the gas compression space while maintaining sufficient back pressure within the gas compression space to assist the piston in returning to its initial position.

[0013] According to one aspect of the invention, the gas conduit includes a continuously open leakage passage connected in parallel with a check valve. This feature prevents the pressure in the gas compression space of the pneumatic spring from rising above a predetermined upper limit, even if the check valve prevents gas backflow.

[0014] According to one aspect of the invention, a continuously open leakage path is integrated into a one-way valve, providing a continuously open constriction section with a predetermined loss coefficient. This minimizes the structural space requirements of the gas flow restriction system.

[0015] According to one aspect of the invention, the leakage channel includes a constriction section having a predetermined loss coefficient. This provides controlled outflow of gas from the gas compression space during movement of the operating piston in a first direction.

[0016] According to one aspect of the invention, the operating piston includes a rod portion, wherein a separate pneumatic spring piston is arranged on the rod portion at a predetermined axial distance from the piston head of the operating piston, such that a collection space for leakage control fluid is arranged between the operating piston and the pneumatic spring piston. This allows control fluid to be recovered without entering the gas compression space, at least preventing excessive control fluid beyond what is required for lubricating the pneumatic spring piston from entering.

[0017] According to one aspect of the invention, the actuating piston includes a rod portion arranged to extend through a gas compression space via a sleeve portion, and the gas compression space forming an annular space surrounding the sleeve portion, the annular space extending axially at least partially over the sleeve portion. In this way, the dimensions of the pneumatic spring assembly in the axial or longitudinal direction can be minimized.

[0018] According to one aspect of the invention, the sleeve portion has a tapered outer surface defining a gas compression space, and the pneumatic spring piston includes an annular recess extending in the axial direction, such that the pneumatic spring piston and the tapered sleeve portion can overlap during the stroke of the operating piston. In this way, the dimensions of the pneumatic spring assembly in the axial or longitudinal direction can be further minimized.

[0019] According to one aspect of the invention, the fuel injector is provided with a sensor arranged in the injector body assembly and configured to monitor the axial position of the operating piston. This allows for more accurate determination of the operating piston's position, thereby enabling more precise control of the fuel quantity.

[0020] According to one aspect of the invention, the sensor configured to monitor the axial position of the operating piston is a position sensor that detects the position of the operating piston.

[0021] According to one aspect of the invention, the sensor configured to monitor the axial position of the operating piston can be a pressure sensor arranged to determine the pressure in one or more of the working space, the gas compression space, and the pumping space of the hydraulic amplifier. In this case, pressure changes in the space where the pressure sensor is arranged are converted into position information of the operating piston by a computer control system.

[0022] According to one aspect of the invention, the sensor configured to monitor the axial position of the operating piston is a position sensor, such as a proximity sensor, and the operating piston includes a tapered, preferably conical, outer surface disposed near the measurement location of the position sensor. Thus, the position sensor measures the radial distance between the sensor and the outer surface of the operating piston, and the measurement is accurate due to the substantially short required measurement range.

[0023] According to one aspect of the invention, the injection valve assembly includes an injection needle biased against a mechanical spring and configured to open under fuel pressure. Thus, the initiation and duration of injection are directly controlled by a hydraulic amplifier.

[0024] According to one aspect of the invention, an operating piston has an axially extending cylindrical recess at its axial end, and a hydraulic amplifier includes a control fluid inlet portion extending into the recess and including an axial channel extending axially to an end section of the control fluid inlet portion. The operating piston includes a radial extension in the recess at the end of the operating piston such that, when the operating piston is in its initial position, the operating piston is provided with an auxiliary working space surrounding the control fluid inlet portion formed by the radial extension, and a flow connection is arranged to extend between the axial channel in the control fluid inlet portion and the auxiliary working space formed by the radial extension in the cylindrical recess, wherein the cross-sectional flow area is arranged to change in response to the axial position of the operating piston.

[0025] In this way, soft-start and soft-stop operation of the piston is achieved advantageously. Because the invention includes a pneumatic spring assembly, this soft-start and soft-stop function does not require any complex control fluid control system.

[0026] According to one aspect of the invention, the fuel injector is provided with a sensor arranged in the injector body assembly and configured to monitor the axial position of the operating piston, wherein the injection valve assembly includes an injection needle biased against a mechanical spring and configured to open by fuel pressure, and the fuel injector is further provided with an external computer control system.

[0027] - Includes predetermined data information regarding the relationship between the axial position of the operating piston and the injection duration. - Configured to receive location information from sensors. - Configured to receive the desired injection duration for the upcoming injection and, based on the desired injection duration, obtain the desired axial position of the operating piston from data information. It is configured to control the supply of pressurized control fluid to the workspace, and It is configured to stop pressurizing the workspace when information obtained from the sensor indicates that the operating piston has reached the desired axial position.

[0028] In this way, the fuel injector can be operated precisely using a position sensor.

[0029] According to one aspect of the invention, the fuel injector does not include a sensor for monitoring the axial position of the operating piston, but instead includes an operating piston hydraulically operated by a control fluid, a control fluid flow control device configured to initiate hydraulic fluid to move the operating piston in a first direction, and to deactivate the hydraulic fluid for a predetermined duration between initiation and deactivation, and an external computer control system.

[0030] - Includes pre-defined data information on the relationship between the duration of start-up time and the duration of injection. - Configured to receive the required spray duration for the upcoming spray and obtain the required start-up time from data information based on the required spray duration. - Configured to control the supply of pressurized control fluid to the workspace, and - Configured to stop pressurizing the workspace when the duration of the startup time ends.

[0031] In this way, the fuel injector can operate precisely without the use of a position sensor.

[0032] The exemplary embodiments of the invention presented in this patent application should not be construed as limiting the applicability of the appended claims. The verb "comprising" as used in this patent application serves as an openness limitation and does not exclude the presence of features not listed. Features described in the dependent claims may be freely combined with each other unless expressly stated otherwise. Novel features considered characteristic of the invention are specifically set forth in the appended claims. Attached Figure Description

[0033] The invention will now be described with reference to the accompanying exemplary schematic diagrams, in which: Figure 1 A fuel injector for an internal combustion piston engine according to one embodiment of the present invention is shown. Figure 2 A hydraulic amplifier according to one embodiment of the present invention is shown, and Figure 3 A hydraulic amplifier according to another embodiment of the present invention is shown. Detailed Implementation

[0034] Figure 1 A fuel injector 10 for an internal combustion piston engine is depicted schematically. The fuel injector 10 comprises two main parts: a hydraulic amplifier 20 for pressurizing fuel to the injection pressure, and an injection valve assembly disposed within a common injector body assembly 102. The hydraulic amplifier 20 is configured to increase the fuel pressure from a lower fuel supply pressure to the injection pressure via a hydraulically driven operating piston 204, the pressurized fuel being subsequently supplied to the combustion chamber 104 of the engine during use.

[0035] The hydraulic amplifier 20 includes: a cylinder 202 disposed within the injector body assembly 20; and an operating piston 204 disposed within the cylinder 202. The cylinder may include multiple sections with different diameters at different longitudinal positions, depending on, for example, actual size requirements. The injector body is an assembly of main components that are detachably assembled to form the injector body assembly. The operating piston 204 partially defines a working space 208 within the cylinder such that the volume of the working space increases when the operating piston moves in a first direction. Movement of the operating piston 204 is achieved by connecting the working space 208 to a pressurized control fluid source 244, which, when the fuel injector 10 is installed and ready for operation, is controllably flow-connected to a control fluid conduit 206 disposed on the injector body assembly 102, the control fluid conduit opening into the working space 208 and extending from the working space 208 to the outer surface of the injector body assembly. When the working space 208 is not pressurized, it is flow-connected to the low-pressure section 228 of the control fluid system (e.g., a fuel tank), allowing control fluid to be discharged from the working space 208 during the return motion of the operating piston 204. The operating piston is in its initial position before pressurized control fluid is applied to the top of the operating piston 204. This allows the piston to reciprocate, pressurizing the fuel to the desired injection pressure and determining the amount of fuel injected. The controllable flow connection is achieved by a control fluid flow control device 226, configured to either introduce pressurized control fluid into the cylinder's working space 208, causing the operating piston 204 to move in a first direction resulting in amplification, or release the pressure of the control fluid in the cylinder's working space 208, thereby returning the operating piston to its initial position. The control fluid flow control device 226 may, for example, include one or more directional valves.

[0036] The hydraulic amplifier includes a pumping space 230, which is partially defined in a cylinder by an operating piston 204, such that the volume of the pumping space 230 decreases as the operating piston moves in a first direction. The pumping space 230 can be understood as a first space in the fuel injector 10 whose volume decreases as the operating piston moves in the first direction. When assembled and ready for use, the pumping space is connected to a fuel source 240 via a fuel inlet conduit 232 disposed on the main body assembly 102. The fuel inlet conduit extends from the pumping space 230 to the outer surface of the injector main body assembly. A one-way valve 234 is disposed on the fuel inlet conduit to allow fuel to enter the pumping space 230 and prevent fuel backflow to the fuel source 240 when the volume of the pumping space decreases. The pumping space 230 is provided with a fuel outlet 236. The fuel outlet 236 is provided with a one-way valve 238 that allows fuel to flow out of the pumping space 230 and prevents fuel backflow into the pumping chamber 230. When the operating piston 204 moves upward as shown in the figure, the pumping space is filled with fuel via the fuel inlet conduit 232. When the operating piston moves downward as shown in the figure (i.e., in the first direction), the operating piston reduces the volume of the pumping space and pressurizes the fuel. The fuel, pressurized to the injection pressure by the hydraulic amplifier 20, is guided to the injection valve assembly 30 located at one end of the injector body assembly. The pressurized fuel is supplied by the fuel injection assembly 30 to the combustion chamber 104 of the engine. The fuel injection assembly 30 shown here is very schematic because it can be implemented in various ways with the fuel injector body assembly connected to the hydraulic amplifier 20. The fuel injection assembly 30 includes an injection needle 302, the position of which determines the operating state of the fuel injector 10—open or closed. The injection needle 302 is kept closed by the assistance of a mechanical spring 308 that pushes the needle 302 against the valve seat 304. When the needle is lifted, i.e., away from the valve seat 304, fuel injection occurs. The fuel outlet 236 of the pumping space 230 in the hydraulic amplifier 20 is fluidly connected to the accumulator 306 of the fuel injection valve assembly 30. When the needle leaves the valve seat 304, pressurized fuel can flow through the valve seat 304 and be ejected from the injection assembly through its injection orifice. In the embodiment shown in the figure, when the axial force generated by the fuel pressure in the accumulator 306 increases to a level exceeding the force exerted by the spring on the needle, the valve needle is lifted, i.e., removed from the valve seat 304. Thus, the operation of the injection assembly 30 is controlled by the fuel pressure. In other words, the injection valve assembly includes an injection needle 302 that is biased against a mechanical spring and configured to open by utilizing the fuel pressure in the accumulator 306. In some practical applications, the injection assembly can also be controlled by utilizing hydraulic pressure applied to the needle, the force of which is in the same direction as the mechanical spring. That is, the injection valve assembly includes an injection needle that is biased by the mechanical spring and the hydraulic pressure during use. In this case, the injection needle is controlled to open electronically by releasing the hydraulic pressure using a solenoid valve.

[0037] The hydraulic amplifier includes a pneumatic spring assembly 210 having a gas compression space 212 for assisting the operating piston 204 to return to its initial position after the pressurization stroke of the hydraulic amplifier's operating piston 204. The gas compression space 212 is partially defined by the operating piston 204 in the cylinder 202. When the operating piston moves in a first direction (i.e., in...) Figure 1 When the fuel injector 10 is in the middle (downward), the volume of the gas compression space 212 decreases, and therefore the pressure in the gas compression space 212 increases. When the stroke of the operating piston is stopped by the controlled fluid flow control device 226 (this is achieved by stopping the pressurization of the working space 208 and connecting the working space 208 to the low-pressure section 228), the pressure in the gas compression space 212 will exert a return force on the operating piston 222. This return force is applied to the operating piston 222 in a second direction opposite to the first direction and assists the operating piston 204 to return to its initial position. A gas conduit 214 is provided, which is arranged in the injector body assembly and leads into the gas compression space 212, and extends from the gas compression space 212 to a coupling arranged on the outer surface of the injector body assembly. When the fuel injector 10 is assembled and ready for use in the engine, the gas conduit is connected to the compressed gas source 242. The preferred gas for the pneumatic spring assembly is air because it is non-toxic and readily available.

[0038] The gas conduit includes a gas flow restriction system 213 that provides gas flow resistance in both directions, such that the flow resistance toward the gas compression space 212 is significantly less than the flow resistance from the gas compression space 212 itself, by at most half, preferably at most one-tenth. Thus, during compression by moving the operating piston in the first direction, the ease and speed at which the gas compression space is filled is greater than the speed and ease at which gas is discharged from the gas compression space during compression. This can be achieved by including a one-way valve 216 in the gas conduit 214. The one-way valve allows gas to flow only toward the gas compression space 212 and prevents backflow. However, the pneumatic spring assembly 210 is arranged with a continuously open leakage passage that maintains a continuous connection between the gas compression space 212 and the connector (and, in use, the compressed gas source 242). The continuously open leakage passage 218 is connected in parallel with the one-way valve 216, and therefore, when the pressure in the gas compression space 212 is higher than the gas pressure in the compressed gas source 242, gas can escape from the gas compression space 212 and flow back towards the compressed gas source 242—even if the one-way valve is closed. The leakage passage 218 is provided with a constriction section 220, such as an orifice, having a predetermined loss coefficient to limit gas backflow and maintain the desired pressure in the gas compression space. Therefore, the connection at the end of the gas compression space and the leakage passage 218, and when connected to the compressed gas source, also have a continuously open gas flow path with the compressed gas source.

[0039] The compression space 230 is a second space in the fuel injector 10, whose volume decreases when the operating piston moves in the first direction. Since both the compression space 230 and the pumping space are spaces in the fuel injector whose volume decreases when the operating piston moves in the first direction, it is understandable that their actual locations in the hydraulic amplifier may differ in different applications.

[0040] exist Figure 1 In the illustrated embodiment, the amount of fuel injected is proportional to the movement of the working piston 204, and therefore the time for which the working space 208 is pressurized determines the amount of fuel injected. For controlling the injection duration, in practical applications where requirements are not high, providing a sufficiently precise correspondence between the pressurization time of the working space 208 and the amount of fuel injected may be adequate. However, as a further improvement to the fuel injector 10, a sensor 224 is provided, configured to monitor the axial position of the operating piston 204. The axial position refers to the position of the operating piston 204 in the direction of its movement. The sensor 224 is arranged in the injector body assembly so that it can be connected to the required wiring, and it is located near the measurement of the operating piston 204, such as... Figure 1 As shown.

[0041] Preferably, to control the operation of the fuel injector, an external computer control system 50 may be included, which communicates with the sensor 224 and the control fluid flow control device 226 for data transmission. The computer control system 50 includes predetermined data information 52 regarding the relationship between the axial position of the operating piston and the injection duration.

[0042] Computer control system 50, when in accordance with Figure 1 or Figure 2 When used in conjunction with a fuel injector, it is configured to receive information from sensor 224 and to receive or acquire the desired injection duration for an upcoming injection and to acquire the desired axial position of the operating piston from data information 52 based on the desired injection duration. It is also configured to control the supply of pressurized control fluid to the workspace and to stop pressurizing the workspace when the position information obtained from the sensor indicates that the operating piston has reached the desired axial position.

[0043] The configuration of the computer control system includes computer programs that, when executed in the computer control system associated with the internal combustion engine, cause the injectors to operate as described below.

[0044] Before injection, the fuel injector is in Figure 1As shown in the diagram, the working space 208 is depressurized, and the pumping chamber 230 is substantially at the pressure of the fuel in the fuel source, which is lower than the fuel injection pressure. The gas compression space 212 is filled with gas from the compressed gas source 242, preferably compressed air. The initial pressure is preferably about 600-700 kPa(g). When a command to inject fuel into the combustion chamber is received, the position of the directional valve 226 switches to... Figure 1 At an unselected location, a pressurized control fluid source (e.g., hydraulic oil) is connected to the working space 208. The pressure in the working space increases, and the working piston 204 begins to move in a first direction toward the other end of the cylinder. As the piston moves, the fuel pressure in the pumping space 230 and the accumulator chamber 306 of the fuel injection valve assembly 30 increases. As the operating piston moves further, at some point in the movement, the pressure in the accumulator chamber 306 reaches a level capable of providing an axial force to the injection needle 302, exceeding the force applied by the mechanical spring 308, and the needle 302 lifts off the valve seat 304, after which fuel flows out of the injection valve assembly 30. Preferably, as the operating piston moves in the first direction, the position of the working piston 204 is monitored by sensor 224, and fuel injection continues. For each injection, the desired fuel quantity is determined by the control system of the engine on which the injector is mounted, and the amount of fuel injected is proportional to the movement of the working piston 204. When data from sensor 224 indicates that the piston is in a position where the desired amount of fuel has been injected, the directional valve 226 moves back to its original position. Figure 1 The position shown. Therefore, the working piston 204 continues to move in the first direction until the working space 208 is depressurized again. This is achieved by moving the position of the directional valve 226 back to the indicated position. Figure 1 This is achieved at the position shown.

[0045] The movement of the working piston in the first direction also causes an increase in pressure in the gas compression space 212. Even with the one-way valve 216 closed, a small amount of gas continues to flow out of the gas compression space 212, preventing excessive pressure rise in the space 212. Once the desired amount of fuel has been injected, the working space 208 is depressurized. At this point, in order to begin the next injection, the pressurized gas in the gas compression space 212 moves the operating piston back to its initial position. Subsequently, the pressure in the gas compression space is balanced with the pressure in the compressed gas source 242 via the continuously open leakage passage 218.

[0046] Figure 1 The sensor indicated by reference numeral 224 in the attached figure is a position sensor located at the end of cylinder 202. This sensor can be, for example, a proximity sensor, which directly provides position information. Figure 1 The paper also shows an alternative method for implementing a sensor configured to monitor the axial position of the operating piston, namely a pressure sensor 224', such as a piezoelectric pressure sensor. Figure 1It has been disclosed that such a pressure sensor 224' can be arranged to connect to one or more spaces 208, 212, 230 in the injector 10 to determine the pressure behavior therein. Figure 1 In this example, to illustrate the different options, the pressure sensor is connected to the working space 208, the gas compression space 212, and the pumping space 230 of the hydraulic amplifier 20. However, in practical applications, it is sufficient to arrange a pressure sensor to be connected to only one of these spaces. The pressure behavior, i.e., the pressure data, in the space where the pressure sensor is located is converted into position information of the actuating piston 222 by the computer control system 50 with the aid of appropriate computer-aided data processing.

[0047] Figure 2 A hydraulic amplifier 20 according to one embodiment is disclosed. Figure 2 A hydraulically driven operating piston 204, further developed according to the present invention, is disclosed. The operating piston 204 includes a rod 222, with a piston head 221 defining a working space 208 assembled at the end of the rod 22. Furthermore, a separate pneumatic spring piston 223 is arranged at a predetermined axial distance from the piston head 221 on the rod 222, such that a collection space 246 for leakage control fluid is axially arranged between the operating piston and the pneumatic spring piston. The collection space is also defined by the inner wall of the cylinder 202. The pneumatic spring piston 223 has a sealing ring 252 provided near its axial end opposite the piston head 221. A discharge conduit 250 is provided, arranged to pass through the body assembly 102, at the initial position of the operating piston (in... Figure 2 The middle (topmost position) leads into the lower part of the collection space 246 for draining any control fluid from the collection space 246. In this document, "separate" means that the pneumatic spring 252 piston is detachably attached to the rod 222 independently of the piston head 221. For example... Figure 2 As shown, cylinder 202 includes sections with different diameters.

[0048] Sensor 224, configured to monitor the axial position of the operating piston 222, is a position sensor for detecting the position of the operating piston 222. The position sensor is arranged to be connected to the side wall of the cylinder 202 in the injector body 102. More specifically, in Figure 2 In the illustrated embodiment, the position sensor is configured to measure the radial distance from the outer surface of the pneumatic spring piston 223. This is particularly relevant when operating the piston. Figure 2In the illustrated embodiment, the pneumatic spring piston 223 in the rod 222 has a measuring section 248 on its outer surface near the measurement of the position sensor 224. The measuring section includes a distance that varies axially relative to the inner surface of the cylinder, such that the distance from the surface to the position sensor differs when the operating piston is in different axial positions. Thus, the measurement of the radial distance provides the axial position of the operating piston 204. More specifically, the operating piston includes a tapered, preferably conical, measuring section, such as... Figure 2 As shown at angle 242. The tapering form can be linear or non-linear, but the linear form makes it easier to calibrate the position information. The diameter of the pneumatic spring piston at its end near piston head 221 is smaller than the diameter at the other end, and therefore, as the operating piston 204 moves away from its initial position, the position sensor 224 indicates a gradually increasing distance. This provides very accurate axial position information for the operating piston 204.

[0049] like Figure 2 As shown, the rod portion 222 of the operating piston 204 is arranged to extend through a gas compression space via a sleeve portion 254, and the gas compression space forms an annular space surrounding the sleeve portion 254, the compression space extending axially at least partially on the sleeve portion. The compression piston 221 has a skirt section at its end opposite the piston head 221, such that when the operating piston moves in a first direction, the sleeve portion 254 and the compression piston partially overlap each other, making it possible to provide a longer stroke or a shorter hydraulic amplifier 20. The sleeve portion 254 has a tapered outer surface defining the gas compression space. The sleeve portion has a cylindrical inner surface 256, and the rod portion has a circular cross-section. The cylindrical inner surface 256 is provided with a sealing system 258, such as including one or more mechanical seals.

[0050] Figure 2 It is also disclosed that the gas conduit 214 includes a one-way valve 216 that allows gas to flow only in the direction toward the gas compression space 212, and a continuously open leakage passage 218 connected in parallel with the one-way valve is integrated into the one-way valve, providing a continuously open constriction section 220 with a predetermined loss coefficient. This is shown more precisely in the enlarged cross-sectional view of the accompanying drawings. In this way, the gas compression space 212 has a continuously open gas flow path through the valve element of the one-way valve, and requires less drilling through the body assembly 102.

[0051] Figure 3 The upper portion of a hydraulic amplifier 20 according to one embodiment of the present invention, i.e., the portion opposite to the injection valve assembly, is disclosed. The hydraulic amplifier 20 discloses optional modifications to the invention, which can be combined with… Figure 1 and Figure 2 The illustrated implementation is used, even though it is combined here. Figure 2The embodiment shown illustrates this. As is clear from the above description, the movement of the operating piston 222 is achieved by connecting the working space 208 to a pressurized control fluid source 244, which is controllably flow-connected to a control fluid conduit 206 disposed on the injector body assembly 102 and leading into the working space 208 when the fuel injector 10 is installed and ready for operation. The hydraulic amplifier 20 includes: an improved piston head 221 having an axially extending cylindrical recess 260 at its axial end; and a control fluid inlet portion 262 extending into the recess 260, with the control fluid conduit 206 disposed in the control fluid inlet portion 262. The control fluid inlet portion is also generally cylindrical. The end section of the control fluid inlet portion 262 is shown in more detail in an enlarged view above the hydraulic amplifier 20. Here, the operating piston 222 is in its initial position. As shown in the enlarged view, the control fluid conduit 206 in the control fluid inlet portion 262 includes an axial channel 206' that extends axially to the end section of the control fluid inlet portion 262. At the end section of the control fluid inlet portion, the control fluid conduit has one or more radial channels 206.2 that extend radially through the end section of the control fluid inlet portion 262. The radial channels 206.2 continue as axially extending grooves or similar features 206.3 disposed on the outer surface of the control fluid inlet portion 262. The piston head 221 is provided with a radial extension 260.1 in a cylindrical recess 260, the diameter of which is larger than the diameter of the cylindrical recess 260. This extension forms an outward step in the cross-section of the recess 260. The extension is disposed at the axial end of the piston head 221 and has an axial distance L1 from the end face of the cylinder 202 in the injector body assembly 102. When the operating piston 222 is in its initial position, the extension 260.1 forms an annular space surrounding the control fluid inlet portion 262, which is in flow connection with the axially extending groove 206.3 and the radial channel 206.2, as indicated by arrow A. The groove extends axially to a position passing through the control edge 264 formed by the extension 260.1.

[0052] When the operating piston is in its initial position, the groove 206.3 includes a first section 206.3' with a gradually decreasing flow area and a second section 206.3'' with a constant flow area. The first section continues from the radial channel 206.2, and the second section is the end of the axially extending groove 206.3 in the direction indicated by arrow A. Thus, the cross-sectional flow area is arranged to change in response to the axial position of the operating piston. When the operating piston 222 moves along the first direction (in... Figure 3When the piston moves downwards (in the first direction), the axial distance L1 increases, the cross-sectional flow area increases, and the flow resistance decreases due to the movement and the shape of the groove 206.3. As the operating piston moves in the first direction, the flow rate of the control fluid into the radial extension 260.1 increases. This provides a soft-start operation, i.e., a gradual acceleration of the operating piston 222. When the operating piston moves in the second direction (upwards in the figure), this provides a soft-stop operation, i.e., a gradual deceleration of the operating piston 222, because the discharge of the control fluid from the radial extension 260.1 becomes increasingly restricted as the operating piston moves toward its initial position. The soft-start and soft-stop operations are particularly advantageous when used in conjunction with the present invention (i.e., a fuel injector including a pneumatic spring assembly) because continuous control of the control fluid flow is not required.

[0053] When the operating piston is in its initial position, the radial channel 206.2 and the axially extending groove or similar 206.3 constitute a flow connection between the axial channel 206' of the control fluid conduit 206 and the radial extension 260.1 in the cylindrical recess 260. Thus, the operating piston is provided with an auxiliary working space 208' formed by the radial extension 260.1 surrounding the control fluid inlet portion 262.

[0054] While the present invention has been described herein by way of example in conjunction with what is now considered the most preferred embodiment, it will be apparent to those skilled in the art that the basic idea of ​​the invention can be implemented in many ways as technology advances. Therefore, the invention and its embodiments are not limited to the examples and samples described above, but can be varied within the scope of the patent claims and their legal equivalents. Details relating to any of the embodiments described above can be used in another embodiment where technically feasible.

Claims

1. A fuel injector (10) for an internal combustion piston engine, the fuel injector comprising: - A hydraulic amplifier (20) for pressurizing fuel to injection pressure and disposed in the injector body assembly (102); - Injection valve assembly (30), which is arranged in the injector body assembly (102) and configured to supply fuel pressurized by the hydraulic amplifier (20) to the combustion chamber (104) of the engine; The hydraulic amplifier (20) includes: - Cylinder (202), and - An operating piston (204) arranged in the cylinder partially defines a working space (208) in the cylinder such that the volume of the working space increases when the operating piston moves in a first direction; - A control fluid conduit (206) disposed on the injector body assembly (102) and extending into the workspace (208); Its features are, A pneumatic spring assembly (210) includes a gas compression space (212) partially defined by the operating piston (204) in the cylinder (202), such that the volume of the gas compression space (212) decreases as the operating piston moves in the first direction, and the pneumatic spring assembly (210) is arranged to apply a force to the operating piston (204) in a second direction opposite to the first direction to assist the operating piston (204) in returning to its initial position.

2. The fuel injector (10) according to claim 1, characterized in that, The fuel injector includes a control fluid flow control device (226) configured to either introduce pressurized control fluid into the working space (208) of the cylinder located at one end of the operating piston (204), or release the pressure of the control fluid in the working space (208).

3. The fuel injector according to claim 1, characterized in that, A gas conduit (214) is provided, which is arranged in the injector body assembly and leads into the gas compression space (212).

4. The fuel injector according to claim 3, characterized in that, The gas conduit includes a gas flow restriction system (213) that provides gas flow resistance in both directions, such that the flow resistance toward the gas compression space (212) is less than the flow resistance from the gas compression space (212).

5. The fuel injector according to claim 4, characterized in that, The gas conduit includes a one-way valve (216) that allows gas to flow only in the direction toward the gas compression space (212).

6. The fuel injector according to claim 5, characterized in that, The gas conduit includes a continuously open leakage channel (218) connected in parallel with the one-way valve (216).

7. The fuel injector according to claim 6, characterized in that, The continuously open leakage channel (218) is integrated into the check valve, providing a continuously open constriction section (220) with a predetermined loss coefficient.

8. The fuel injector according to claim 1, characterized in that, The operating piston includes a rod (222), wherein a separate pneumatic spring piston (223) is arranged on the rod at a predetermined axial distance from the piston head (221) of the operating piston (204), such that a collection space (246) for leakage control fluid is arranged between the operating piston and the pneumatic spring piston.

9. The fuel injector according to claim 1, characterized in that, The operating piston includes a rod (222) arranged to extend through the gas compression space via a sleeve, and the gas compression space forms an annular space surrounding the sleeve, the annular space extending axially at least partially over the sleeve.

10. The fuel injector according to claim 9, characterized in that, The sleeve portion has a tapered outer surface defining the gas compression space, and the pneumatic spring piston (223) includes an annular recess extending in the axial direction.

11. The fuel injector according to claim 1, characterized in that, The fuel injector is equipped with sensors (224, 224') arranged in the injector body assembly and configured to monitor the axial position of the operating piston (204).

12. The fuel injector according to claim 11, characterized in that, The sensor (224) is a position sensor (224), and the operating piston (204) includes a tapered, preferably conical, outer surface disposed near the measurement of the position sensor (224).

13. The fuel injector according to any one of the preceding claims, characterized in that, The operating piston (222) has an axially extending cylindrical recess (260) at its axial end, and the hydraulic amplifier (20) includes a control fluid inlet portion (262) extending into the recess (260) and including an axial channel (206') extending axially to an end section of the control fluid inlet portion (262), and the operating piston includes a radial extension (260.1) located in the recess (260) at the end of the operating piston (222), such that when When the operating piston is in its initial position, the operating piston is provided with an auxiliary working space (208') formed by the radial extension (260.1) surrounding the control fluid inlet portion (262), and a flow connection is arranged to extend between the axial channel (206') in the control fluid inlet portion (262) and the auxiliary working space formed by the radial extension (260.1) in the cylindrical recess (260), wherein the cross-sectional flow area is arranged to change in response to the axial position of the operating piston.

14. The fuel injector according to claim 11, characterized in that, The injection valve assembly (30) includes an injection needle biased against a mechanical spring and configured to open by fuel pressure, and the fuel injector (10) includes: External computer control system (50), the external computer control system - Includes predetermined data information regarding the relationship between the axial position of the operating piston and the injection duration. - Configured to receive location information from sensors. - Configured to receive the desired injection duration for the upcoming injection and obtain the desired axial position of the operating piston from the data information based on the desired injection duration. - Configured to control the supply of pressurized control fluid to the workspace, and - It is configured to stop pressurizing the workspace when the information obtained from the sensor indicates that the operating piston has reached the desired axial position.

15. The fuel injector according to claim 2, characterized in that, The control fluid flow control device (226) is configured to initiate hydraulic fluid to move the operating piston (222) in a first direction and to deactivate the hydraulic fluid for a predetermined duration between initiation and deactivation, and an external computer control system (50) thereof. - Includes predetermined data information regarding the relationship between the duration of the start-up time and the injection duration. - Configured to receive the desired spray duration for the upcoming spray and obtain the desired start time from the data information based on the desired spray duration. - Configured to control the supply of pressurized control fluid to the workspace, and - Configured to stop pressurizing the workspace when the duration of the startup time ends.

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