Electronic unit pump of diesel engine

Abstract

The invention provides a heavy oil electronic unit pump for a diesel engine. The heavy oil electronic unit pump is used for solving the problem that in the prior art, a clear oil unit pump is directly applied to a heavy oil product, and an electromagnetic valve fails easily. The pump comprises an electromagnetic valve, an oil injection pump body, a plunger and barrel assembly, a bypass valve assembly and a guide assembly, the guide matching part comprises a guide sleeve and a top block; a cooling oil cavity used for introducing cooling oil is formed between the guide sleeve and a shell of the proportional electromagnetic valve, a leakage oil duct communicated with the outside is arranged on the guide sleeve, and the leakage oil duct is communicated with the atmosphere; the cooling oil cavity is in fluid communication with a plunger sleeve oil return cavity in the plunger and barrel assembly through a sliding gap between the ejector rod and the guide sleeve, so that part of cooling oil in the cooling oil cavity and part of fuel oil in the fuel oil return cavity can oppositely permeate and be mixed through the sliding gap, and the mixed oil liquid is discharged through the leakage oil channel.

Description

Technical Field

[0001] This application relates to the field of diesel engine technology, specifically to a heavy oil electronically controlled unit pump for diesel engines. Background Technology

[0002] Electronically controlled unit pumps can achieve flexible control of diesel engine injection patterns, reducing fuel consumption and emissions under various operating conditions. Current electronically controlled unit pumps primarily use light diesel fuel and typically employ solenoid valves to control the opening and closing of bypass valves. Since the solenoid valves are in direct contact with the light diesel fuel, they are prone to failure due to corrosion and heat caused by heavy fuel oil if the light diesel is replaced with heavy fuel oil. Therefore, the conventional electronically controlled unit pump structure cannot meet the requirements for heavy fuel oil use. Summary of the Invention

[0003] This application provides a heavy oil electronically controlled unit pump for diesel engines, which solves the problem that applying existing clean oil unit pumps directly to heavy oil products can easily lead to solenoid valve failure.

[0004] The technical solution of this application is as follows:

[0005] This application provides a heavy oil electronically controlled unit pump for diesel engines, comprising: a solenoid valve, a fuel injection pump body, a plunger assembly installed in the fuel injection pump body, a bypass valve assembly installed in the plunger assembly, and a guide assembly that enables the bypass valve assembly and the solenoid valve to slide together.

[0006] The guide assembly includes: a guide sleeve and a top block slidably disposed therein; the guide sleeve is connected between the housing of the proportional solenoid valve and the plunger assembly; and the top block is connected between the push rod of the proportional solenoid valve and the bypass valve assembly.

[0007] A cooling oil chamber for introducing cooling oil is formed between the guide sleeve and the housing of the proportional solenoid valve. The guide sleeve is provided with a leakage oil passage that communicates with the outside and is in communication with the atmosphere.

[0008] The cooling oil chamber and the plunger sleeve return oil chamber in the plunger assembly are fluidly connected through the sliding gap between the push rod and the guide sleeve, so that part of the cooling oil in the cooling oil chamber and part of the fuel in the fuel return oil chamber can permeate and mix with each other through the sliding gap, and the mixed oil is discharged through the leakage oil passage.

[0009] Preferably, the plunger assembly includes a plunger sleeve and a plunger; the bypass valve assembly includes a bypass valve and a bypass valve sleeve.

[0010] The plunger sleeve is provided with an axial hole, a radial through hole, and an axial connecting hole that connects the axial hole and the radial through hole.

[0011] One end of the plunger extends into the axial hole, and a plunger cavity communicating with the axial communication hole is formed between the plunger and the plunger sleeve.

[0012] The bypass valve sleeve is press-fitted into the radial through hole;

[0013] The bypass valve is slidably inserted into the axial through hole of the bypass valve sleeve, and the bypass valve is connected to the top block;

[0014] The bypass valve sleeve has a plunger sleeve inlet chamber and a plunger sleeve return chamber respectively formed on both sides, which are connected through the inner hole of the bypass valve.

[0015] A bypass valve sleeve cavity is formed between the bypass valve and the bypass valve, which can communicate with the oil return chamber of the plunger sleeve, and the bypass valve sleeve cavity is connected to the axial connecting hole and the high-pressure oil outlet on the plunger sleeve through the radial hole on the bypass valve sleeve.

[0016] The bypass valve, driven by the proportional valve, can block the connection between the plunger sleeve return oil chamber and the bypass valve sleeve chamber.

[0017] Preferably, a fuel return chamber, a fuel inlet chamber, a mixing chamber, and a lubricating oil chamber are sequentially formed between the fuel injection pump body and the plunger sleeve;

[0018] The fuel return chamber is connected to the plunger sleeve return chamber, and the fuel return chamber is located on the side close to the bypass valve sleeve.

[0019] The fuel inlet chamber is connected to the plunger sleeve inlet chamber via the fuel inlet passage on the plunger sleeve.

[0020] The lubricating oil cavity is connected to the outer circle of the plunger through the lubricating oil passage on the plunger sleeve;

[0021] The mixing chamber is used to collect leaked fuel from the fuel inlet chamber and leaked lubricating oil from the lubricating oil chamber.

[0022] Preferably, the plunger sleeve oil inlet chamber is sealed by a baffle connected to the plunger sleeve;

[0023] The bypass valve is connected to the baffle via a bypass valve spring.

[0024] Preferably, the fuel injection pump body is provided with a low-pressure return port communicating with the fuel return chamber, a low-pressure inlet port communicating with the fuel inlet chamber, a mixing port communicating with the mixing chamber, and a lubricating port communicating with the lubricating oil chamber.

[0025] Preferably, the pressure in the mixing chamber is atmospheric pressure.

[0026] Preferably, the guide sleeve has multiple annular grooves on the end face surrounding the top block.

[0027] The beneficial effects of this application are as follows:

[0028] A closed cooling oil chamber is constructed between the solenoid valve housing and the guide sleeve, and pressurized cooling oil is introduced into it. This cooling oil chamber directly surrounds the heat-generating parts of the solenoid valve, and its primary function is to directly and efficiently remove the heat generated by the solenoid valve during operation, preventing it from failing due to overheating at the source.

[0029] High-temperature heavy oil seeping from the plunger sleeve's return oil chamber meets and mixes with low-temperature cooling oil seeping from the external cooling oil chamber in the same tiny sliding gap between the top block and the guide sleeve. By properly setting the cooling oil pressure, a stable fluid pressure barrier can be formed at this gap, pointing from the cooling oil towards the internal fuel chamber. This barrier effectively blocks most of the high-temperature heavy oil from continuing to seep towards the solenoid valve, thus cutting off the main path for heat and contaminants to propagate to the solenoid valve and preventing direct contact between the solenoid valve and the fuel. Finally, a specially designed leakage channel on the guide sleeve provides a unique, controlled outlet for these two opposing, mixed oil streams. The mixed oil is actively guided and discharged from the pump, rather than left to stagnate or continue to seep inward. This ensures the smooth flow of the sliding gap and continuously removes any mixed oil that may carry impurities and heat. Attached Figure Description

[0030] Figure 1 This is a cross-sectional view of the heavy oil electronically controlled unit pump in the embodiments of this application;

[0031] Figure 2 This is an external view of the heavy oil electronically controlled unit pump in the embodiments of this application;

[0032] Figure 3 This is an external view of the heavy oil single-hole unit pump in the embodiments of this application;

[0033] In the diagram: 1 - plunger sleeve, 2 - baffle, 3 - bypass valve sleeve, 4 - bypass valve spring, 5 - bypass valve, 6 - plunger, 7 - upper spring seat, 8 - plunger spring, 9 - lower spring seat, 10 - sleeve, 11 - fuel injection pump body, 12 - lubricating oil chamber, 13 - mixing oil chamber, 14 - fuel inlet chamber, 15 - fuel return chamber, 16 - top block, 17 - guide sleeve, 18 - solenoid valve, 19 - cooling oil chamber, 20 - plunger sleeve return chamber, 21 - bypass valve sleeve chamber, 22 - plunger sleeve inlet chamber, 23 - high pressure outlet, 24 - low pressure inlet, 25 - mixing oil port, 26 - lubricating oil port, 27 - low pressure return hole, 28 - cooling oil inlet passage, 29 - leakage passage, 30 - cooling oil return passage. Detailed Implementation

[0034] Reference Figures 1 to 3 This embodiment provides a heavy oil electronically controlled unit pump for a diesel engine. The heavy oil electronically controlled unit pump is mounted on the lifting mechanism of the diesel engine and includes:

[0035] Solenoid valve 18, fuel injection pump body 1, plunger assembly installed in the fuel injection pump body 1, bypass valve 5 assembly installed in the plunger assembly, and guide assembly that enables sliding connection between the bypass valve 5 assembly and the solenoid valve 18.

[0036] The guide assembly includes a guide sleeve 17 and a top block 16 slidably disposed therein. The guide sleeve 17 is connected between the housing of the proportional solenoid valve 18 and the plunger assembly, and the top block 16 is connected between the push rod of the proportional solenoid valve 18 and the bypass valve 5 assembly.

[0037] A cooling oil chamber 19 for introducing cooling oil is formed between the guide sleeve 17 and the housing of the proportional solenoid valve 18. The guide sleeve 17 is provided with a leakage oil passage 29 that communicates with the outside and is in communication with the atmosphere.

[0038] The cooling oil chamber 19 and the plunger sleeve return oil chamber 20 in the plunger assembly are fluidly connected through the sliding gap between the push rod and the guide sleeve 17, so that part of the cooling oil in the cooling oil chamber 19 and part of the fuel in the fuel return oil chamber 15 can permeate and mix with each other through the sliding gap, and the mixed oil is discharged through the leakage oil passage 29.

[0039] A closed cooling oil chamber 19 is constructed between the housing of the solenoid valve 18 and the guide sleeve 17, and pressurized cooling oil is introduced into it. This cooling oil chamber 19 directly surrounds the heat-generating parts of the solenoid valve 18, and its primary function is to directly and efficiently remove the heat generated by the solenoid valve 18 during operation, thereby preventing it from failing due to overheating.

[0040] The high-temperature heavy oil seeping from the plunger sleeve return oil chamber 20 and the low-temperature cooling oil seeping from the external cooling oil chamber 19 meet and mix in the same tiny sliding gap between the top block 16 and the guide sleeve 17. By properly setting the pressure of the cooling oil, a stable fluid pressure barrier pointing from the cooling oil to the internal fuel chamber can be formed at this gap. This barrier effectively blocks most of the high-temperature heavy oil from continuing to seep towards the solenoid valve 18, thereby cutting off the main path for heat and contaminants to propagate to the solenoid valve 18 and preventing direct contact between the solenoid valve 18 and the fuel. Finally, through the specially designed leakage oil passage 29 on the guide sleeve 17, a unique and controlled outlet is provided for these two opposing and mixed oil streams. The mixed oil is actively guided and discharged from the pump, rather than left to stagnate or continue to seep inward. This ensures the smooth flow of the sliding gap and continuously removes the mixed oil that may carry impurities and heat.

[0041] In this embodiment of the application, the plunger sleeve 1 and the plunger 6 constitute the above-mentioned plunger assembly. The plunger sleeve 1 is provided with an axial hole, a radial through hole, and an axial connecting hole that connects the axial hole and the radial through hole. One end of the plunger 6 extends into the axial hole, and a plunger cavity that communicates with the axial connecting hole is formed between the plunger 6 and the plunger sleeve 1. The inner circle of the plunger sleeve 1 and the mating section of the plunger 6 are provided with four levels of annular grooves from top to bottom. The four levels of annular grooves are, in order from top to bottom, the first annular groove, the second annular groove, the third annular groove, and the fourth annular groove. The plunger sleeve 1 is assembled inside the fuel injection pump body 1. Between the fuel injection pump body 1 and the plunger sleeve 1, a fuel return chamber 15, a fuel inlet chamber 14, a mixing chamber 13, and a lubricating oil chamber 12 are formed in sequence. Among them, the first annular groove is connected to the fuel return chamber 15 through the internal oil passage on the plunger sleeve 1, the second annular groove is connected to the fuel inlet chamber 14 through the fuel oil passage on the plunger sleeve 1, the third annular groove is connected to the mixing chamber 13 through the internal oil passage on the plunger sleeve 1, and the second annular groove is connected to the lubricating oil chamber 12 through the lubricating oil passage on the plunger sleeve 1.

[0042] The fuel injection pump body 1 is provided with a low-pressure fuel inlet 24, a mixing fuel inlet 25, a lubricating oil inlet 26 and a low-pressure fuel return port. The low-pressure fuel inlet 24 is connected to the fuel inlet chamber 14, the mixing fuel inlet 25 is connected to the mixing fuel chamber 13, the lubricating oil inlet 26 is connected to the lubricating oil chamber 12, and the low-pressure fuel return port is connected to the fuel return chamber 15.

[0043] In this embodiment, the fourth annular groove is connected to the lubricating oil chamber 12, and the pressure in the fourth annular groove is the same as the lubricating oil pressure. The fuel pressure in the second annular groove is basically the same as the fuel inlet pressure. The third annular groove is connected to the mixing oil chamber 13, and the pressure is atmospheric. Under pressure, the fuel in the second annular groove and the lubricating oil in the fourth annular groove enter the third annular groove through the gap of the plunger assembly to form a mixed oil, which is then discharged through the mixing oil chamber 13 and the mixing oil port 2525.

[0044] By using the four-stage annular grooves and corresponding independent chamber structure on the mating section of plunger 6 and plunger sleeve 1, the basic oil pumping function of the plunger assembly is realized while effectively solving the problems of heavy oil lubrication and leakage control: the pressure gradient design from top to bottom makes high-pressure fuel mainly flow back from the second annular groove, significantly reducing the amount of high-pressure leakage; at the same time, by using the difference between the fuel pressure in the second annular groove and the lubricating oil pressure in the fourth annular groove, the fuel and lubricating oil are forced to flow in opposite directions in the gap of plunger 6 and mix in the third annular groove. This mixed oil is actively discharged through the mixing oil chamber 13. This process not only removes wear products that may contaminate the fuel and excess lubricating oil from the precision mating surface, preventing excessive lubricating oil from entering the fuel system, but also uses the circulating mixed oil to continuously cool and clean the plunger assembly. Thus, even under the harsh working conditions of high viscosity and easy coking of heavy oil, the plunger assembly can still maintain reliable lubrication, effective sealing and long-term stable operation.

[0045] In the embodiment of the application, the bypass valve sleeve 3 and the bypass valve 5 constitute the above-mentioned bypass valve 5 assembly. The bypass valve sleeve 3 is press-fitted into the radial through hole, and the bypass valve 5 is slidably inserted into the axial through hole of the bypass valve sleeve 3. The bypass valve 5 is connected to the top block 16. The volume between the bypass valve sleeve 3 and the bypass valve 5 forms the bypass valve sleeve cavity 21. The two sides of the bypass valve sleeve 3 are respectively formed with a plunger sleeve inlet cavity 22 and a plunger sleeve return cavity 20 that are connected through the inner hole of the bypass valve 5. The plunger sleeve return cavity 20 can communicate with the bypass valve sleeve cavity 21.

[0046] The bypass valve sleeve 3 and the bypass valve 5 can form a conical seal on the drive sleeve of the proportional valve, thereby blocking the connection between the plunger sleeve return oil chamber 20 and the bypass valve sleeve chamber 21.

[0047] In this embodiment, the bypass valve sleeve 3 has two radial holes at the middle position with an angle of 90° that are connected to the bypass valve sleeve cavity 21. One of the radial holes is connected to the axial connecting hole of the plunger sleeve 1 to connect to the plunger cavity; the other radial hole is connected to the high-pressure oil outlet on the plunger sleeve 1.

[0048] By utilizing the design of the bypass valve sleeve 3 and its two radially arranged holes at specific angles, one serves as a controlled inlet for low-pressure fuel, connecting the plunger chamber and the bypass valve sleeve cavity 21. This allows fuel filling during the filling phase and provides a continuation of the high-pressure build-up space during the injection phase. The other serves as the sole fuel outlet, directly connecting the bypass valve sleeve cavity 21 to the external high-pressure fuel line interface. This independent inlet and outlet design minimizes the flow path and directional direction of fuel between the plunger chamber, bypass valve sleeve cavity 21, and the final outlet. When the bypass valve 5 completes its conical seal under the drive of the solenoid valve 18, the closed volume formed by the aforementioned channels and cavities becomes a precisely controlled unit for high-pressure fuel. The establishment and release of its pressure depend entirely on the opening and closing of the bypass valve 5, thus achieving rapid and precise electronic control of the injection start point and injection quantity. Simultaneously, all high-pressure bearing interfaces are confined within the precision pair of plunger sleeve 1 and bypass valve sleeve 3, greatly improving the pump's sealing reliability and pressure-bearing capacity.

[0049] In this embodiment, the tail hole of the bypass valve 5 connects the middle hole of the bypass valve 5 with the oil return chamber 20 of the plunger sleeve, which is used to balance the pressure difference between the oil inlet chamber 22 of the plunger sleeve 1 and the oil return chamber 20 of the plunger sleeve 1, preventing the bypass valve 5 from closing again due to pressure fluctuations during pressure relief, and improving the stability of the fuel injection pump during operation.

[0050] In this embodiment of the application, the plunger sleeve 1 plunger sleeve inlet chamber 22 is sealed by the baffle 2 connected to the plunger sleeve 1, and the bypass valve 5 is connected to the baffle 2 by the bypass valve spring 4; the baffle 2 is installed on the right side of the plunger sleeve 1 by screws, and the bypass valve spring 4 is installed between the neck of the bypass valve 5 and the baffle 2.

[0051] By using a separate component, baffle 2, which is screwed together with plunger sleeve 1, a reliable seal is achieved for the complex oil passage end face inside plunger sleeve 1. Specifically, baffle 2 closes the internal chamber, including the plunger sleeve inlet chamber 22 of plunger sleeve 1, at one end along its axial direction, forming a stable hydraulic boundary. The bypass valve spring 4 is precisely installed between the neck of bypass valve 5 and baffle 2. This arrangement allows the spring preload to act directly and coaxially on bypass valve 5, providing a stable and predictable return force for bypass valve 5. As a detachable end cap, the baffle 2 greatly facilitates the machining and cleaning of the internal channels (such as the oil inlet chamber and oil return chamber) of the plunger sleeve 1. Secondly, it separates the spring mounting seat from the plunger sleeve 1 body that bears high pressure, avoiding the direct machining of complex spring seats on the plunger sleeve 1 and simplifying the structure of core precision components. Finally, the clear spring mounting reference ensures that the bypass valve 5 can quickly and accurately return to the preset opening position after the electromagnetic driving force is removed. This is the key to achieving rapid fuel cut-off and stable cyclic operation, ensuring the repeatability and reliability of the electronic injection action.

[0052] The guide sleeve 17 and the solenoid valve 18 are mounted on the left side of the plunger sleeve 1 by screws. The top block 16 is slidably mounted in the central hole of the guide sleeve 17. The two together form the aforementioned guide assembly. The push rod of the solenoid valve 18 contacts the left end of the top block 16, and the right end of the top block 16 contacts the tail of the bypass valve 5.

[0053] The guide sleeve 17 is provided with multiple annular grooves on the end face of the top block 16. The multiple annular grooves are used to reduce fuel leakage. The annular groove at the tail of the guide sleeve 17 is connected to the leakage oil passage 29 of the guide sleeve 17.

[0054] The cooling oil inlet channel 28 and the coolant return channel 30 are set on the guide sleeve 17. During operation, fuel under a certain pressure in the plunger sleeve return chamber 20 enters the leakage oil channel 29 on the guide sleeve 17 through the gap between the top block 16 and the guide sleeve 17. The multiple lubricating oil grooves of the top block 16 play a role in improving the lubrication effect and preventing jamming. The pressure of the leakage oil channel 29 is atmospheric pressure. Under a certain pressure, part of the cooling oil in the cooling oil chamber 19 enters the leakage oil channel 29 through the gap between the top block 16 and the guide sleeve 17 to form a mixture with the leaked fuel, and then is discharged, preventing further mixing of the cooling oil and fuel.

[0055] In this embodiment, the assembly relationship between the plunger 6, the upper spring seat 7, the plunger spring 8, the lower spring seat 9, and the sleeve 10 is prior art.

[0056] In this embodiment of the application, the working process of the above-mentioned heavy oil electronically controlled unit pump is as follows:

[0057] During the fuel filling stage: The lifting mechanism and the plunger spring 8 work together to drive the plunger 6 downward. Fuel enters the fuel inlet chamber 14 of the injection pump body 1 through the low-pressure inlet port 24, then enters the plunger sleeve inlet chamber 22 of the plunger sleeve 1 through the internal fuel inlet passage of the plunger sleeve 1, and enters the plunger sleeve return chamber 20 through the middle and tail holes of the bypass valve 5. At this time, the plunger chamber formed by the plunger sleeve 1 and the plunger 6 is under negative pressure due to the downward movement of the plunger 6. Fuel in the plunger sleeve return chamber 20 enters the plunger chamber through the cone surface of the bypass valve sleeve 3 and the bypass valve 5. The remaining fuel in the plunger sleeve return chamber 20 enters the fuel return chamber 15 through the internal return passage of the plunger sleeve 1, and finally flows out through the low-pressure return port 27 of the injection pump body 1.

[0058] Fuel supply phase: When the plunger 6 rises to a certain point, the control system sends a current signal, and the solenoid valve 18 generates thrust to push the top block 16 towards the bypass valve 5. Under the action of the thrust, the bypass valve 5 overcomes the spring force of the bypass valve spring 4 and moves towards the baffle 2 until the bypass valve 5 contacts the bypass valve sleeve 3 to complete the conical seal, separating the low-pressure fuel in the plunger sleeve return chamber 20 from the fuel in the bypass valve sleeve chamber 21 and the plunger chamber. The fuel in the plunger chamber and the bypass valve sleeve chamber 21 is compressed to generate high pressure under the action of the continuing upward plunger 6. When the injector opening pressure is reached, the high-pressure fuel enters the injector through the high-pressure outlet of the plunger sleeve 1 and the high-pressure fuel pipe, and is then injected to begin fuel supply.

[0059] Depressurization stage: When the proportional solenoid valve 18 is de-energized and no longer provides thrust, the bypass valve 5 returns to its original position under the action of the bypass valve spring 4. The bypass valve 5 opens, and the high-pressure fuel in the plunger chamber is unloaded to the fuel return chamber 15 through the cone surface of the bypass valve 5 and the bypass valve sleeve 3. Then, it enters the fuel return chamber 15 and the low-pressure return port 27 through the internal oil passage of the plunger sleeve 1 and enters the fuel tank to complete the depressurization.

[0060] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Those skilled in the art can understand that implementing all or part of the processes of the above embodiments and making equivalent changes according to the claims of this application still fall within the scope of this application.

Claims

1. A heavy oil electronically controlled unit pump for a diesel engine, characterized in that, include: Solenoid valve 18, fuel injection pump body (1), plunger assembly installed in the fuel injection pump body (1), bypass valve (5) assembly installed in the plunger assembly, and guide assembly that realizes the sliding connection between the bypass valve (5) assembly and the solenoid valve (18). The guide assembly includes a guide sleeve (17) and a top block (16) slidably disposed therein. The guide sleeve (17) is connected between the housing of the proportional solenoid valve (18) and the plunger assembly, and the top block (16) is connected between the push rod of the proportional solenoid valve (18) and the bypass valve (5) assembly. A cooling oil chamber (19) for introducing cooling oil is formed between the guide sleeve (17) and the housing of the proportional solenoid valve (18). The guide sleeve (17) is provided with a leakage oil passage (29) that communicates with the outside and is connected to the atmosphere. The cooling oil chamber (19) and the plunger sleeve return oil chamber (20) in the plunger assembly are fluidly connected through the sliding gap between the push rod and the guide sleeve (17), so that part of the cooling oil in the cooling oil chamber (19) and part of the fuel in the fuel return oil chamber (15) can permeate and mix with each other through the sliding gap, and the mixed oil is discharged through the leakage oil passage (29).

2. The heavy oil electronically controlled unit pump for diesel engines according to claim 1, characterized in that, The plunger assembly includes a plunger sleeve (1) and a plunger (6); the bypass valve (5) assembly includes a bypass valve (5) and a bypass valve sleeve (3). The plunger sleeve (1) is provided with an axial hole, a radial through hole, and an axial connecting hole that connects the axial hole and the radial through hole. One end of the plunger (6) extends into the axial hole, and a plunger cavity communicating with the axial communication hole is formed between the plunger (6) and the plunger sleeve (1); The bypass valve sleeve (3) is press-fitted into the radial through hole; The bypass valve (5) is slidably inserted into the axial through hole of the bypass valve sleeve (3), and the bypass valve (5) is connected to the top block (16). The bypass valve sleeve (3) has a plunger sleeve (1) plunger sleeve inlet chamber (22) and a plunger sleeve return chamber (20) respectively formed on both sides through the inner hole of the bypass valve (5). A bypass valve sleeve cavity (21) is formed between the bypass valve (5) and the bypass valve (5) to communicate with the return oil cavity (20) of the plunger sleeve, and the bypass valve sleeve cavity (21) is connected to the axial connection hole and the high pressure oil outlet on the plunger sleeve (1) through the radial hole on the bypass valve sleeve 3. The bypass valve (5) can, under the drive of the proportional valve, block the connection between the plunger sleeve return oil chamber (20) and the bypass valve sleeve chamber (21).

3. The heavy oil electronically controlled unit pump for diesel engines according to claim 2, characterized in that, A fuel return chamber (15), a fuel inlet chamber (14), a mixing chamber (13) and a lubricating chamber (12) are formed sequentially between the fuel injection pump body (1) and the plunger sleeve (1). The fuel return chamber (15) is connected to the plunger sleeve return chamber (20), and the fuel return chamber (15) is located on the side close to the bypass valve sleeve (3). The fuel inlet chamber (14) is connected to the plunger sleeve inlet chamber (22) of the plunger sleeve (1) through the fuel inlet passage on the plunger sleeve (1); The lubricating oil cavity (12) is connected to the outer circle of the plunger (6) through the lubricating oil passage on the plunger sleeve (1); The mixing chamber (13) is used to collect leaked fuel from the fuel inlet chamber (14) and leaked lubricating oil from the lubricating oil chamber (12).

4. The heavy oil electronically controlled unit pump for diesel engines according to claim 2, characterized in that, The plunger sleeve (1) is sealed in the oil inlet chamber (22) by a baffle (2) connected to the plunger sleeve (1); The bypass valve (5) is connected to the baffle (2) via the bypass valve spring (4).

5. The heavy oil electronically controlled unit pump for diesel engines according to claim 3, characterized in that, The fuel injection pump body 1 is provided with a low-pressure return port communicating with the fuel return chamber (15), a low-pressure inlet port (24) communicating with the fuel inlet chamber (14), a mixing port (25) communicating with the mixing chamber (13), and a lubricating port (26) communicating with the lubricating chamber (12).

6. The heavy oil electronically controlled unit pump for diesel engines according to claim 5, characterized in that, The pressure in the mixing oil chamber (13) is atmospheric pressure.

7. The heavy oil electronically controlled unit pump for diesel engines according to claim 1, characterized in that, The guide sleeve (17) has multiple annular grooves on the end face of the top block (16).

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