A marine diesel engine high-pressure common rail system pressure stabilizing assembly

Abstract

This invention discloses a pressure stabilizing component for a high-pressure common rail system of a marine diesel engine, including a high-pressure common rail, a rail pressure sensor, an electronically controlled pressure relief valve, a pulse damper, and connecting pipes. The pulse damper is connected to the high-pressure fuel pump to suppress pressure oscillations caused by the cyclical and pulsating fuel supply of the high-pressure fuel pump. The inlet and outlet of the high-pressure common rail adopt a tapered tapered design to increase the common rail volume and reduce pressure fluctuations caused by frequent injector activation. The electronically controlled pressure relief valve receives electrical signals from the electronic control unit (ECU) and opens under extreme and normal pressure conditions to guide fuel recirculation, protect components, and improve pressure regulation accuracy. Compared with traditional high-pressure common rail components, this invention solves the problem of common rail pressure fluctuations caused by pulsating fuel supply from the high-pressure fuel pump and frequent injector activation, offering advantages such as stability, reliability, improved injection accuracy, and enhanced common rail pressure stability.

Description

Technical Field

[0001] This invention relates to the field of marine diesel engine technology, specifically to a pressure stabilizing component for a high-pressure common rail system, particularly suitable for improving pressure fluctuations within the high-pressure common rail, enhancing injection accuracy, and improving system stability in marine diesel engines. Background Technology

[0002] Common rail technology for marine diesel engines originated in the 20th century. Early mechanical diesel engines suffered from insufficient oil pressure at low speeds, resulting in poor diesel atomization and incomplete combustion. This led to insufficient torque, excessive black smoke, high fuel consumption, and severe environmental pollution at low speeds. Since the 1990s, global emission regulations for diesel engines have become increasingly stringent. To meet these requirements, common rail technology utilizes a common rail for fuel storage. Regardless of engine speed, the common rail maintains a stable and extremely high pressure. Consequently, injection pressure is unaffected by engine speed, enabling high-pressure injection even at low speeds, resulting in excellent atomization and solving the diesel engine pollution problem.

[0003] However, in existing high-pressure common rail systems, the high-pressure fuel pump is typically connected directly to the high-pressure common rail, which in turn connects to multiple injectors. Because the high-pressure fuel pump uses a periodic, pulsating fuel supply method, and the injectors frequently open and close during their operating cycle, pressure fluctuations and oscillations are easily generated within the high-pressure common rail. This pressure instability leads to inaccurate fuel injection control and reduced atomization, especially under multiple injection strategies, where control precision further deteriorates, affecting the overall performance and emissions levels of the diesel engine.

[0004] Therefore, how to effectively suppress pressure fluctuations in the high-pressure common rail and improve system pressure stability has become a pressing technical problem to be solved in the design of high-pressure common rail systems for marine diesel engines. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of large pressure fluctuations and oscillations in the high-pressure common rail during the working cycle of a diesel engine. It provides a pressure stabilizing component for a high-pressure common rail system of a marine diesel engine. The component uses a pulse damper to convert the pulsed, periodic flow into a continuous flow, reducing the fluctuation of the oil inlet. The inlet and outlet ports adopt a conical reduction type to increase the internal volume of the common rail. The conical design helps to reduce the impact of frequent injector opening on the internal pressure. Combined with the return oil regulation effect of the electronically controlled pressure relief valve, the internal pressure stability of the common rail is improved.

[0006] The technical solution of the present invention is as follows: A voltage stabilizing component for a high-pressure common rail system of a marine diesel engine, comprising: The high-pressure common rail pipe has an internal pressure accumulator chamber. Several oil inlets and outlets are formed on the pipe wall, and each inlet and outlet is a tapered, tapering structure that gradually decreases in diameter from the outside of the pipe wall towards the pressure accumulator chamber. One end of the high-pressure common rail pipe has a rail pressure sensor mounting hole, and the other end has an electrically controlled pressure relief valve mounting hole. A pressure relief oil hole is formed on the pipe wall near the electrically controlled pressure relief valve mounting hole.

[0007] A rail pressure sensor is fixedly installed in the rail pressure sensor mounting hole, and the sensing end of the rail pressure sensor extends into the accumulator chamber. It is used to detect the fuel pressure in the high-pressure common rail in real time and convert the pressure signal into an electrical signal to be output to the electronic control unit (ECU).

[0008] An electronically controlled pressure relief valve is fixedly installed within the mounting hole, with its valve core connection extending into the high-pressure common rail. The axial length of this valve core connection is greater than the axial distance between the end face of the high-pressure common rail and the pressure relief port, ensuring rapid connection of the pressure relief channel when the valve core opens, achieving sensitive pressure relief. The electronically controlled pressure relief valve receives a control signal from the ECU and opens under extreme overpressure or normal pressure regulation conditions, guiding fuel back through the pressure relief port.

[0009] A pulse damper is disposed between the high-pressure fuel supply pump and the high-pressure common rail, along the fuel flow direction. A first flange and a second flange are respectively provided at both ends of the pulse damper, wherein the second flange is used to connect to the outlet of the high-pressure fuel supply pump. The pulse damper is used to transform the periodic pulsating fuel flow output by the high-pressure fuel supply pump into a continuous and stable flow, thereby suppressing inlet pressure oscillations.

[0010] A connecting pipe is disposed between the pulse damper and the high-pressure common rail. One end of the connecting pipe is a flange end, which is sealed and fixedly connected to the first flange of the pulse damper; the other end of the connecting pipe is a mounting shoulder, which is sealed and fixedly connected to the oil inlet side of the high-pressure common rail, thereby realizing fuel communication between the oil outlet of the pulse damper and the oil inlet of the high-pressure common rail.

[0011] As a preferred embodiment, the fuel inlet and outlet are symmetrically arranged on both radial sides of the accumulator, and the multiple fuel inlets and outlets are alternately arranged along the axial direction of the high-pressure common rail. This arrangement helps to distribute the fuel evenly within the accumulator and reduces flow disturbance.

[0012] As a preferred embodiment, the pulse damper is a mechanical pulse damper, which has an elastic diaphragm or air bladder structure inside for absorbing pressure pulsations.

[0013] As a preferred embodiment, the mounting shoulder of the connecting pipe is connected to the oil inlet side wall of the high-pressure common rail pipe by an interference fit or a threaded seal, and a sealing ring is provided at the connection to ensure that the high-pressure seal is leak-free.

[0014] As a preferred embodiment, the cone angle of the tapered converging structure is 15° to 30°, whereby the cone angle is defined as the angle between the generatrix of the converging section and the central axis of the oil inlet or outlet. This angle range allows for a good balance between increasing the equivalent volume and reducing flow resistance.

[0015] As a preferred embodiment, the high-pressure common rail is forged from high-strength alloy steel, and the inner diameter of the accumulator is 20mm to 30mm, with a wall thickness of not less than 5mm, to meet the strength and corrosion resistance requirements of marine diesel engines under high-pressure conditions.

[0016] As a preferred embodiment, the internal volume of the pulse damper is 1 to 2 times the volume of the accumulator chamber of the high-pressure common rail, so as to achieve sufficient pulsation absorption effect.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The damping effect of the pulse damper reduces the internal pressure fluctuations caused by periodic and pulsating oil supply, transforms the pulsed and periodic flow into continuous flow, reduces the impact on the common rail, and improves the reliability of the components.

[0018] 2) The use of tapered and shrink-type inlet and outlet ports can increase the internal volume of the common rail. When the injector injects oil, the increased volume is relatively small, which can reduce the impact of multiple injections on the internal pressure of the common rail. During injection, a pressure wave is generated in the common rail. The tapered structure can act as a transducer of acoustic impedance, so that the pressure wave is reflected less when it passes through, thus reducing high-frequency pressure oscillation.

[0019] 3) An electronically controlled pressure relief valve is adopted. Compared with the mechanical pressure relief valve, which only releases pressure when it exceeds the safe pressure, it can be opened flexibly and works with the ECU (electronic control unit) to regulate pressure and improve the accuracy of pressure regulation. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings... Figure 1 This is a schematic diagram of the overall assembly three-dimensional structure of the pressure stabilizing component of the high-pressure common rail system for marine diesel engines of the present invention under operating conditions. Figure 2 This is a half-sectional view of the high-pressure common rail pipe in this invention.

[0021] The markings in the diagram and their corresponding component names are as follows: 1: High-pressure common rail 101: Oil Inlet 102: Oil outlet 103: Rail pressure sensor mounting hole 104: Mounting hole for electrically controlled pressure relief valve 105: Accumulator Chamber 106: Pressure relief oil hole 2: Rail pressure sensor 3: Electrically controlled pressure relief valve 4: Pulse damper 401: First Flange 402: Second flange 5: Connecting pipe 501: Flange end 502: Install shoulder Detailed Implementation The technical solution of the present invention will be clearly and completely described below with reference to application examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] Example 1 like Figure 1 As shown, this embodiment provides a pressure stabilizing component for a high-pressure common rail system of a marine diesel engine, including a high-pressure common rail pipe 1, a rail pressure sensor 2, an electronically controlled pressure relief valve 3, a pulse damper 4, and a connecting pipe 5. The high-pressure common rail pipe (1) is provided with tapered converging inlet / outlet ports 101 and 102 and a pressure relief oil hole 106; the rail pressure sensor 2 is installed at one end of the common rail pipe, and the electronically controlled pressure relief valve 3 is installed at the other end with its valve core connecting length longer than the distance from the end face to the pressure relief oil hole; the pulse damper 4 is connected to the oil inlet side of the common rail pipe through the connecting pipe 5. This invention suppresses fuel supply pulsation through the pulse damper, increases the equivalent volume and reduces pressure wave reflection through the tapered oil port, and achieves active and precise pressure relief through the electronically controlled pressure relief valve. The synergistic effect of the three significantly reduces pressure fluctuations in the common rail pipe, improves fuel injection accuracy and system stability, and is suitable for high-pressure common rail systems of marine diesel engines.

[0023] The specific structure is as follows: like Figure 1 and Figure 2 As shown, the high-pressure common rail pipe 1 is a long, hollow tube with an internal pressure accumulator chamber 105. Several oil inlets 101 and outlets 102 are provided on the pipe wall of the high-pressure common rail pipe 1, and the oil inlets 101 and outlets 102 are arranged symmetrically along the length of the pipe (e.g., alternately arranged on both sides of the pressure accumulator chamber 105). One end of the high-pressure common rail pipe 1 (e.g., Figure 1 The left end) is provided with a rail pressure sensor mounting hole 103, and the other end (such as...) Figure 1An electrically controlled pressure relief valve mounting hole 104 is provided at the right end. Figure 2 As shown in the half-sectional view, both the inlet 101 and outlet 102 adopt a tapered tapering structure, meaning the oil passage diameter gradually decreases from the outer wall of the common rail towards the accumulator chamber 105. The inlet and outlet are arranged on both sides of the accumulator chamber 105, allowing for a smooth transition when fuel enters and flows out. Furthermore, a pressure relief oil hole 106 is provided on the bottom wall of the high-pressure common rail 1 near the mounting hole 104 of the electronically controlled pressure relief valve.

[0024] The rail pressure sensor 2, which is electronically controlled, is installed at one end of the high-pressure common rail 1 to measure the internal pressure of the high-pressure common rail 1 and convert it into an electrical signal for transmission to the ECU (Electronic Control Unit). It is fixedly installed in the rail pressure sensor mounting hole 103 by means of threads or snaps. The sensing probe of the rail pressure sensor 2 extends into the accumulator chamber 105 to detect the fuel pressure inside the high-pressure common rail 1 in real time and convert the pressure signal into an electrical signal for output to the diesel engine's ECU.

[0025] The electronically controlled pressure relief valve 3 is an electromagnetically controlled pressure relief valve, with its valve body fixedly installed inside the electronically controlled pressure relief valve mounting hole 104. The length of the valve core connection part of the electronically controlled pressure relief valve 3 (i.e., the part extending into the high-pressure common rail 1) is designed to be slightly greater than the distance between the end face of the high-pressure common rail 1 and the pressure relief oil hole 106. When the ECU sends an opening signal, the valve core moves, opening the pressure relief passage, allowing the fuel in the accumulator chamber 105 to flow back to the low-pressure return oil circuit through the pressure relief oil hole 106, thereby achieving rapid pressure relief.

[0026] The pulse damper 4 is a mechanical pulse damper with an internal elastic diaphragm or air bladder structure. A first flange 401 and a second flange 402 are respectively located at both ends of the pulse damper 4. The first flange 401 is used to connect to the flange end 501 of the connecting pipe 5, and the second flange 402 is used to connect to the oil outlet of the high-pressure oil pump. The function of the pulse damper 4 is to absorb the periodic pulsating energy output by the high-pressure oil pump using its internal compressible medium (gas or spring), converting the pulsating flow into a continuous and stable flow.

[0027] The connecting pipe 5 is a metal fitting with a flange end 501 at one end and a mounting shoulder 502 at the other end. The flange end 501 is fastened to the first flange 401 of the pulse damper 4 with bolts or clamps, and a sealing gasket is clamped to achieve a high-pressure seal. The mounting shoulder 502 is inserted into the oil inlet side of the high-pressure common rail pipe 1 and fixed by interference fit or welding to ensure no leakage at the connection.

[0028] In this embodiment, the voltage stabilizing component is installed between the high-pressure fuel pump and the injector. The specific working process is as follows: 1. Oil inlet pressure stabilization stage: The pulsating fuel output from the high-pressure fuel pump first enters the pulse damper 4. The elastic element inside the pulse damper 4 absorbs the peak and trough values ​​of the flow pulsation through compression and expansion, converting the pulsating flow into a continuous, pressure-stable fuel flow. The stable fuel then enters the accumulator chamber 105 of the high-pressure common rail 1 via the connecting pipe 5.

[0029] 2. Pressure detection and control stage: The rail pressure sensor 2 monitors the pressure in the accumulator chamber 105 in real time and sends the signal to the ECU. The ECU compares the detected value with the target value and dynamically adjusts the pressure in the common rail by controlling the opening of the fuel metering valve and the opening and closing of the electronically controlled pressure relief valve 3. When the pressure is lower than the target value, the fuel supply is increased; when the pressure is higher than the target value, the ECU opens the electronically controlled pressure relief valve 3, and some fuel flows back through the pressure relief port 106, causing the pressure to drop rapidly to the target range.

[0030] 3. Pressure fluctuation suppression phase: When the fuel injector opens frequently, the instantaneous fuel injection generates a pressure wave within the accumulator chamber 105. At this time, the tapered, tapered fuel inlet 101 and fuel outlet 102 serve a dual purpose: Volume effect: The conical structure effectively increases the volume of the accumulator chamber 105, thus reducing the pressure change caused by the same amount of fuel injection.

[0031] Acoustic impedance gradient effect: The tapered channel acts as an acoustic impedance gradient device. When the pressure wave propagates from the accumulator 105 to the oil port, the impedance gradually changes, reducing the reflection of the pressure wave at the port, thereby effectively suppressing high-frequency pressure oscillation. As an optional implementation, the high-pressure common rail 1 is forged from high-strength alloy steel (such as 38CrMoAl), and the inner diameter of the accumulator chamber 105 is 20~30mm, with a wall thickness of not less than 5mm. The cone angle (i.e., the angle between the generatrix of the tapered section and the axis) of the oil inlet 101 and the oil outlet 102 is preferably 15°~30°. The volume of the pulse damper 4 is 1~2 times the volume of the common rail, and it is filled with nitrogen or has a pre-set spring stiffness. The inner diameter of the connecting pipe 5 is the same as the large end diameter of the oil inlet 101 to reduce flow resistance. Comparative tests show that, under the same injection conditions, the common rail pressure fluctuation amplitude using the components of this embodiment is reduced by approximately 60% compared to the traditional straight-through common rail, and the pressure recovery time is shortened by 40%. The electronically controlled pressure relief valve 3, in conjunction with the ECU, can achieve a pressure control accuracy of ±1MPa, which is significantly better than mechanical pressure relief valves (which typically only activate when the overpressure exceeds 10%). This invention, through the synergistic action of the pulse damper 4, the tapered conical inlet / outlet ports, and the electronically controlled pressure relief valve 3, achieves multi-stage suppression and active regulation of high-pressure common rail pressure fluctuations. It features a compact structure, high reliability, and is suitable for high-pressure common rail systems of various types of marine diesel engines, effectively solving the problems of large pressure fluctuations and inaccurate injection control present in the prior art.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A voltage stabilizing component for a high-pressure common rail system of a marine diesel engine, characterized in that, include: A high-pressure common rail (1) has a pressure accumulator (105) inside. The high-pressure common rail (1) has several oil inlets (101) and oil outlets (102) on its pipe wall. Each oil inlet (101) and oil outlet (102) is a tapered tapered structure with a gradually decreasing inner diameter from the outside of the pipe wall toward the pressure accumulator (105). One end of the high-pressure common rail (1) is provided with a rail pressure sensor mounting hole (103), and the other end is provided with an electric pressure relief valve mounting hole (104). A pressure relief oil hole (106) is opened on the pipe wall near the electric pressure relief valve mounting hole (104). The rail pressure sensor (2) is fixedly installed in the rail pressure sensor mounting hole (103), and the sensing end of the rail pressure sensor (2) extends into the pressure storage chamber (105); An electrically controlled pressure relief valve (3) is fixedly installed in the electrically controlled pressure relief valve mounting hole (104), and the valve core connection part of the electrically controlled pressure relief valve (3) extends into the high pressure common rail pipe (1). The axial length of the valve core connection part is greater than the axial distance between the end face of the high pressure common rail pipe (1) and the pressure relief oil hole (106). A pulse damper (4) is disposed between the high-pressure fuel pump and the high-pressure common rail (1) along the fuel flow direction. A first flange (401) and a second flange (402) are respectively disposed at both ends of the pulse damper (4), wherein the second flange (402) is used to connect to the outlet of the high-pressure fuel pump. A connecting pipe (5) is disposed between the pulse damper (4) and the high-pressure common rail (1). One end of the connecting pipe (5) is a flange end (501), which is sealed and fixedly connected to the first flange (401) of the pulse damper (4). The other end of the connecting pipe (5) is a mounting shoulder (502), which is sealed and fixedly connected to the oil inlet side of the high-pressure common rail (1), thereby realizing the fuel communication between the oil outlet of the pulse damper (4) and the oil inlet (101) of the high-pressure common rail (1).

2. The pressure stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The oil inlet (101) and oil outlet (102) are symmetrically arranged on both sides of the accumulator (105), and multiple oil inlets (101) and multiple oil outlets (102) are alternately arranged along the axial direction of the high-pressure common rail (1).

3. The voltage stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The pulse damper (4) is a mechanical pulse damper, which has an elastic diaphragm or air bladder inside for absorbing pressure pulsations.

4. The voltage stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The mounting shoulder (502) of the connecting pipe (5) is connected to the oil inlet side wall of the high pressure common rail pipe (1) by interference fit or threaded seal, and a sealing ring is provided at the connection.

5. The voltage stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The cone angle of the tapered tapered structure is 15° to 30°, and the cone angle is defined as the angle between the generatrix of the tapered section and the central axis of the oil inlet (101) or oil outlet (102).

6. The pressure stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The high-pressure common rail pipe (1) is forged from high-strength alloy steel, and the inner diameter of the accumulator chamber (105) is 20mm to 30mm, and the wall thickness is not less than 5mm.

7. The pressure stabilizing component for a high-pressure common rail system of a marine diesel engine according to claim 1, characterized in that, The internal volume of the pulse damper (4) is 1 to 2 times the volume of the accumulator chamber (105) of the high-pressure common rail (1).

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