Injector uninterrupted fuel supply system and diesel engine

Abstract

The present invention discloses an uninterrupted fuel supply system for a fuel injector and a diesel engine. The fuel supply system includes a fuel injection pump and a fuel injector. The fuel pump outlet and the fuel injector pipe of the fuel injector are connected through a high-pressure oil pipe, and the fuel pump outlet is connected to a compressed oil chamber. A low-pressure control valve is provided in the fuel injector body, and the opening pressure of the low-pressure control valve is greater than the fuel inlet pressure of the fuel injection pump. When the fuel injection pump is pumping oil, the low-pressure control valve opens to supply high-pressure fuel to the fuel injector. When the fuel injection pump is not working, the low-pressure control valve closes, and the fuel injection pump still supplies low-pressure fuel to the fuel injector. The low-pressure fuel circulates. When the diesel engine is under low load, the low-pressure fuel heats the fuel injector. When the diesel engine is under high load, the low-pressure fuel flows inside the fuel injector, absorbs the heat of the fuel injector, and reduces the temperature of the fuel injector. The fuel injector has good reliability. In particular, for heavy oil diesel engines, before the diesel engine is started, the low-pressure circulating oil preheats the fuel injector in advance, improving the fluidity of the heavy oil and achieving a spray atomization effect, thereby achieving heavy oil starting and shutdown.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engines, in particular to an uninterrupted fuel supply system for a fuel injector and a diesel engine. Background Art

[0002] In a marine heavy fuel oil diesel engine, each injector is typically paired with an injection pump. A high-pressure fuel line connects the pump and the injector, supplying fuel to the injector. The pump has a delivery valve. When the fuel pressure in the pump exceeds the opening pressure of the valve, the valve opens, allowing fuel to flow to the injector. When the plunger's spiral groove connects to the oil inlet and return ports, the valve closes, stopping the pump's fuel supply. Fuel remains in the high-pressure fuel line, allowing the next pump to quickly build pressure. However, the presence of fuel can cause hydraulic vibration in the fuel supply system, affecting system reliability.

[0003] The cooling of the injector relies on the water jacket on the cylinder head and the engine oil. When the diesel engine is under low load, the temperature of the injector is low, which makes the heavy oil fluidity and atomization effect poor. When the diesel engine is under high load, the temperature of the injector is high, which cannot meet the cooling needs of the injector. Summary of the Invention

[0004] In view of the above shortcomings, the technical problem to be solved by the present invention is: to provide an uninterrupted fuel supply system for an injector and a diesel engine, wherein the fuel supply system can continuously supply fuel to the injector. When the diesel engine is under low load, the fuel heats the injector, and when the diesel engine is under high load, the fuel cools the injector.

[0005] In order to solve the above-mentioned first technical problem, the technical solution of the present invention is:

[0006] An uninterrupted fuel supply system for a fuel injector, comprising:

[0007] A fuel injection pump, the fuel injection pump comprising a pump body and a plunger pair disposed within the pump body, the pump body being provided with an oil pump inlet and return oil hole and an oil pump outlet oil hole, the plunger pair comprising a plunger and a plunger sleeve, the plunger sleeve and the pump body forming a low-pressure oil chamber of the oil pump, the oil pump inlet and return oil hole being in communication with the low-pressure oil chamber of the oil pump, the plunger and the plunger sleeve forming a compression oil chamber, the plunger sleeve being provided with a plunger inlet and return oil hole, the plunger inlet and return oil hole being used to connect the low-pressure oil chamber of the oil pump with the compression oil chamber;

[0008] A fuel injector, the fuel injector comprising a fuel injector body, a needle valve disposed within the fuel injector body, and a needle valve return spring; the fuel injector body being provided with a fuel injector pipe, a nozzle, and a fuel injector oil return hole; a fuel injector body oil inlet passage and a needle valve oil inlet passage being provided between the fuel injector pipe and the nozzle; the needle valve being provided with a needle valve pressure surface, a pressure accumulator being provided at the needle valve pressure surface, the pressure accumulator being in communication with the needle valve oil inlet passage and the nozzle, respectively;

[0009] The oil pump outlet and the injector pipe are connected via a high-pressure oil pipe.

[0010] It is characterized by:

[0011] The oil outlet hole of the oil pump is connected to the compression oil chamber;

[0012] A low-pressure control valve is provided in the injector body, and the opening pressure of the low-pressure control valve is greater than the oil inlet pressure of the injection pump;

[0013] When the pressure in the compression oil chamber exceeds the opening pressure of the low-pressure control valve, the low-pressure control valve opens, the injector body oil inlet passage and the needle valve oil inlet passage are connected, and the fuel in the compression oil chamber enters the pressure accumulation chamber through the high-pressure oil pipe, the injector body oil inlet passage, and the needle valve oil inlet passage in sequence. The fuel acts on the pressure surface of the needle valve. The force of the fuel acting on the pressure surface of the needle valve is greater than the force of the needle valve return spring on the needle valve, the needle valve rises, and the fuel in the pressure accumulation chamber is sprayed out through the nozzle.

[0014] When the pressure of the compression oil chamber is lower than the opening pressure of the low-pressure control valve, the low-pressure control valve is closed, the oil inlet passage of the injector body is connected to the oil return hole of the injector, the low-pressure control valve is closed, and the fuel from the injection pump continuously flows into and out of the injector.

[0015] Preferably, the low-pressure control valve comprises a low-pressure control valve core and a low-pressure control valve core return spring;

[0016] A low-pressure control valve core hole is provided at the end of the needle valve, and the low-pressure control valve core slides in the low-pressure control valve core hole. A low-pressure control valve core pressure surface is provided at one end of the low-pressure control valve core extending into the low-pressure control valve core hole. At the low-pressure control valve core pressure surface, the needle valve and the low-pressure control valve core form a low-pressure valve core control chamber. The needle valve is provided with a needle valve oil inlet hole for connecting the injector body oil inlet oil path and the low-pressure valve core control chamber. The low-pressure control valve core is provided with a low-pressure control valve core oil return oil path communicating with the low-pressure valve core control chamber, and the needle valve is provided with a needle valve oil return hole.

[0017] The fuel in the compression oil chamber sequentially passes through the oil pump outlet, the high-pressure oil pipe, the injector pipe and the injector body oil inlet passage and enters the low-pressure valve core control chamber. When the force of the fuel acting on the pressure surface of the low-pressure control valve core is greater than the force of the low-pressure control valve core return spring on the low-pressure control valve core, the low-pressure control valve opens, the low-pressure control valve core rises, and the low-pressure valve core control chamber is connected to the needle valve oil inlet passage. The fuel in the low-pressure valve core control chamber enters the pressure accumulator chamber, pushing the needle valve to rise, and the fuel in the pressure accumulator chamber is sprayed out through the nozzle.

[0018] When the force of the fuel acting on the pressure surface of the low-pressure control valve core is less than the force of the low-pressure control valve core return spring on the low-pressure control valve core, the low-pressure control valve core return oil circuit is connected with the needle valve return oil hole, and the needle valve return oil hole is connected with the injector return oil hole, and the fuel continuously flows into and out of the injector.

[0019] Preferably, the injector pipe extends into the injector body, the needle valve return spring is located between a first needle valve spring seat and a second needle valve spring seat, the first needle valve spring seat rests on the injector pipe, and the low-pressure control valve core return spring is located between the low-pressure control valve core and the second needle valve spring seat.

[0020] Preferably, the low-pressure control valve core return spring is located between the low-pressure control valve core spring seat and the low-pressure control valve core, and the low-pressure control valve core spring seat abuts against the second needle valve spring seat.

[0021] Preferably, the injector body is provided with a spring cavity, and the first needle valve spring seat, the needle valve return spring, the second needle valve spring seat, the low-pressure control valve core spring seat and the low-pressure control valve core return spring are all located in the spring cavity;

[0022] The injector body is provided with an injector body oil return path, the injector body oil return path is communicated between the spring chamber and the needle valve oil return hole, and the spring chamber is communicated with the injector oil return hole.

[0023] Preferably, the low-pressure control valve core oil return oil circuit includes a low-pressure control valve core oblique oil circuit and a low-pressure control valve core annular oil circuit that are connected;

[0024] When the low-pressure control valve is closed, the annular oil path of the low-pressure control valve core is communicated with the oil return hole of the needle valve.

[0025] Preferably, the needle valve lift is H1, H1 = (0.5-0.7) mm.

[0026] Preferably, the diameter of the oil return hole of the needle valve is R, R=(1-1.5) mm, and the lift of the low-pressure control valve core is H2, H2=(2-2.5) mm.

[0027] Preferably, the opening pressure of the low-pressure control valve core is F1, and the pressure of the low-pressure oil chamber of the oil pump is F2.

[0028] 2.8F2≤F1≤3.2F2.

[0029] In order to solve the above second technical problem, the technical solution of the present invention is:

[0030] A diesel engine comprises: a cylinder head and a fuel tank, and also comprises the above-mentioned uninterrupted fuel supply system for the fuel injector, wherein the fuel injector is mounted on the cylinder head, the fuel injector pipe and the cylinder head are spaced apart to form the cylinder oil return path, the cylinder head is provided with a cylinder head oil return hole, the cylinder oil return path is connected between the fuel injector oil return hole and the cylinder head oil return hole, and the cylinder head oil return hole and the oil pump inlet and return hole are respectively connected to the fuel tank.

[0031] After adopting the above technical solution, the beneficial effects of the present invention are:

[0032] (1) Not only does the fuel injection pump supply high-pressure fuel to the fuel injector when pumping oil, but it also supplies low-pressure fuel to the fuel injector when the fuel injection pump is not working. The low-pressure fuel circulates. When the diesel engine is under low load, the low-pressure fuel heats the fuel injector. When the diesel engine is under high load, the low-pressure fuel flows inside the fuel injector, absorbs the heat of the fuel injector, reduces the temperature of the fuel injector, and improves the reliability of the fuel injector. Especially for heavy oil diesel engines, before the diesel engine is started, the low-pressure circulating oil preheats the fuel injector in advance, the heavy oil has good fluidity, and the injection atomization effect of the heavy oil is guaranteed, realizing the start and shutdown of heavy oil;

[0033] (2) The fuel injection pump has no oil outlet valve. High-pressure fuel exists only when pumping oil. The amount of high-pressure fuel in the system is greatly reduced, and the hydraulic vibration generated by the high-pressure fuel is also greatly reduced, thus improving the reliability of the system.

[0034] (3) When low-pressure fuel circulates, low-pressure fuel always exists in the system, and oil pressure can be quickly built up when pumping oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the uninterrupted fuel supply system of the fuel injector of the present invention;

[0036] Figure 2 yes Figure 1 A magnified structural diagram of the fuel injection pump;

[0037] Figure 3 yes Figure 1 A schematic diagram of the enlarged structure of the middle fuel injector;

[0038] Figure 4 yes Figure 3 A schematic diagram of the enlarged structure of part A in the middle (low-pressure control valve closed);

[0039] Figure 5 yes Figure 3 A schematic diagram of the enlarged structure of part A in the middle (low-pressure control valve is open);

[0040] Figure: 1. Fuel injection pump; 10. Roller; 11. Pump body; 12. Oil pump outlet hole; 13. Plunger; 14. Plunger sleeve; 15. Low-pressure oil chamber of the oil pump; 16. Compression oil chamber; 17. Plunger oil return hole; 18. Base circle; 19. Fuel supply cam; 111. Plunger spiral groove; 2. Fuel injector; 201. Fuel injector body; 202. Needle valve; 203. Needle valve return spring; 204. Fuel injector pipe; 205. Nozzle; 206. Fuel injector oil return hole; 207. Fuel inlet passage of the fuel injector body; 208. Oil inlet passage of the needle valve; 209. Pressure surface of the needle valve ; 210, pressure accumulator chamber; 211, low-pressure control valve core; 212, low-pressure control valve core return spring; 213, low-pressure valve core control chamber; 214, needle valve oil inlet hole; 215, needle valve oil return hole; 216, low-pressure control valve core pressure surface; 217, first needle valve spring seat; 218, second needle valve spring seat; 219, low-pressure control valve core spring seat; 220, injector body return oil circuit; 221, low-pressure control valve core oblique oil circuit; 222, low-pressure control valve core annular oil circuit; 3, high-pressure oil pipe; 4, cylinder head; 41, cylinder body return oil circuit; 42, cylinder head return oil hole. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] Example 1

[0043] like Figure 1-Figure 5 As shown in the figure, a fuel injector uninterrupted fuel supply system includes:

[0044] The fuel injection pump 1 includes a pump body 11 and a plunger pair disposed within the pump body 11. The pump body 11 is provided with an oil pump inlet and return oil hole and an oil pump oil outlet hole 12. The plunger pair includes a plunger 13 and a plunger sleeve 14. The plunger sleeve 14 and the pump body 11 form an oil pump low-pressure oil chamber 15. The oil pump inlet and return oil hole are connected to the oil pump low-pressure oil chamber 15. The plunger 13 and the plunger sleeve 14 form a compression oil chamber 16. The plunger sleeve 14 is provided with a plunger inlet and return oil hole 17. The plunger inlet and return oil hole 17 is used to connect the oil pump low-pressure oil chamber 15 and the compression oil chamber 16.

[0045] Injector 2, which includes an injector body 201, a needle valve 202 disposed within the injector body 201, and a needle valve return spring 203. The injector body 201 is provided with an injector pipe 204, a nozzle 205, and an injector oil return hole 206. The injector pipe 204 and the nozzle 205 are connected by an injector body oil inlet passage 207 and a needle valve oil inlet passage 208. The needle valve 202 is provided with a needle valve pressure surface 209, and a pressure storage chamber 210 is provided at the needle valve pressure surface 209. The pressure storage chamber 210 is connected to the needle valve oil inlet passage 208 and the nozzle 205, respectively.

[0046] The oil pump outlet 12 and the injector pipe 204 are connected through the high-pressure oil pipe 3;

[0047] The oil pump outlet hole 12 is directly connected to the compression oil chamber 16;

[0048] A low-pressure control valve is provided in the injector body 201, and the opening pressure of the low-pressure control valve is greater than the oil inlet pressure of the injection pump 1;

[0049] When the roller 10 contacts the fuel supply cam 19, the plunger 13 compresses the fuel. When the pressure in the compression oil chamber 16 exceeds the opening pressure of the low-pressure control valve, the low-pressure control valve opens, and the injector body oil inlet passage 207 and the needle valve oil inlet passage 208 are connected. The fuel in the compression oil chamber 16 enters the pressure accumulation chamber 210 in sequence through the high-pressure oil pipe 3, the injector body oil inlet passage 207, and the needle valve oil inlet passage 208. The fuel acts on the needle valve pressure surface 209. The force of the fuel on the needle valve pressure surface 209 is greater than the force of the needle valve return spring 203 on the needle valve 202. The needle valve 202 lifts, and the fuel in the pressure accumulation chamber 210 is sprayed out through the nozzle 205.

[0050] When the roller 10 contacts the base circle 18, the plunger spiral groove 111 is connected to the plunger oil inlet and return hole 17, and the compression oil chamber 16 is connected to the oil pump low-pressure oil chamber 15. At this time, the pressure of the compression oil chamber 16 is equal to the oil inlet pressure of the injection pump 1, and the pressure of the compression oil chamber 16 is lower than the opening pressure of the low-pressure control valve. The low-pressure control valve is closed, and the injector body oil inlet oil path 207 is connected to the injector oil return hole 206. The fuel from the injection pump 1 continuously flows into and out of the injector.

[0051] Furthermore, the low-pressure control valve includes a low-pressure control valve core 211 and a low-pressure control valve core return spring 212;

[0052] A low-pressure control valve core hole is provided at the end of the needle valve 202. A low-pressure control valve core 211 slides in the low-pressure control valve core hole. A low-pressure control valve core pressure surface 216 is provided at the end of the low-pressure control valve core 211 extending into the low-pressure control valve core hole. At the low-pressure control valve core pressure surface 216, the needle valve 202 and the low-pressure control valve core 211 form a low-pressure valve core control chamber 213. The needle valve 202 is provided with a needle valve oil inlet hole 214 for connecting the injector body oil inlet oil passage 207 and the low-pressure valve core control chamber 213. The low-pressure control valve core 211 is provided with a low-pressure control valve core oil return oil passage communicating with the low-pressure valve core control chamber 213. The needle valve 202 is provided with a needle valve oil return hole 215.

[0053] The fuel in the compression oil chamber 16 sequentially passes through the oil pump outlet 12, the high-pressure oil pipe 3, the injector pipe 204, and the injector body oil inlet passage 207 and enters the low-pressure valve core control chamber 213. The fuel pressure in the compression oil chamber 16 and the fuel pressure in the low-pressure valve core control chamber 213 are equal. When the roller 10 contacts the oil supply cam 19, the fuel in the low-pressure valve core control chamber 213 becomes high-pressure fuel. The force of the fuel acting on the low-pressure control valve core pressure surface 216 is greater than the force of the low-pressure control valve core return spring 212 on the low-pressure control valve core 211. The low-pressure control valve core 211 rises, connecting the low-pressure valve core control chamber 213 with the needle valve oil inlet passage 208. The fuel in the low-pressure valve core control chamber 213 enters the pressure accumulator chamber 210, pushing the needle valve 202 up, and the fuel in the pressure accumulator chamber 210 is sprayed out through the nozzle 205.

[0054] When the roller 10 contacts the base circle 18, the force of the fuel acting on the pressure surface 216 of the low-pressure control valve core is less than the force of the low-pressure control valve core return spring 212 on the low-pressure control valve core 211, the low-pressure control valve core return oil circuit is connected to the needle valve return oil hole 215, the needle valve return oil hole 215 is connected to the injector return oil hole 206, and the fuel continuously flows into and out of the injector 2.

[0055] Furthermore, the injector pipe 204 extends into the injector body 201, the needle valve return spring 203 is located between the first needle valve spring seat 217 and the second needle valve spring seat 218, the first needle valve spring seat 217 rests on the injector pipe 204, and the low-pressure control valve core return spring 212 is located between the low-pressure control valve core 211 and the second needle valve spring seat 218.

[0056] Furthermore, the low-pressure control valve core return spring 212 is located between the low-pressure control valve core spring seat 219 and the low-pressure control valve core 211 , and the low-pressure control valve core spring seat 219 abuts against the second needle valve spring seat 218 .

[0057] Furthermore, the injector body 201 is provided with a spring chamber, in which the first needle valve spring seat 217, the needle valve return spring 203, the second needle valve spring seat 218, the low-pressure control valve core spring seat 219 and the low-pressure control valve core return spring 212 are all located; the injector body 201 is provided with an injector body return oil path 220, which is connected between the spring chamber and the needle valve return oil hole 215, and the spring chamber is connected to the injector oil return hole 206.

[0058] Furthermore, the low-pressure control valve core oil return circuit includes a low-pressure control valve core oblique oil circuit 221 and a low-pressure control valve core annular oil circuit 222 that are connected to each other. The low-pressure control valve core oblique oil circuit 221 is connected to the low-pressure valve core control chamber 213; when the roller 10 contacts the base circle 18, the low-pressure control valve core annular oil circuit 222 is connected to the needle valve oil return hole 215.

[0059] Furthermore, the lift of the needle valve 202 is H1, H1 = (0.5-0.7) mm, so as to obtain better circulation, and at the same time, the impact force when the needle valve 202 is opened is relatively small.

[0060] Furthermore, the diameter of the needle valve oil return hole 215 is R, R = (1-1.5) mm, and the lift of the low-pressure control valve core 211 is H2, H2 = (2-2.5) mm, to ensure good flow and reduce the impact force when the low-pressure control valve core 211 closes. The low-pressure control valve core 211 has a relatively large lift. To mitigate the impact surface pressure of the valve core during resetting, the sealing surface is designed with a flat structure to achieve good surface pressure and improve system reliability.

[0061] The opening pressure of the low-pressure control valve core is F1, and the pressure of the low-pressure oil chamber of the oil pump is F2. F2 is approximately equal to three times F1. Preferably, 2.8F2≤F1≤3.2F2 to ensure that when the plunger of the oil pump in other cylinders is relieved, the pressure fluctuation is reduced, and the low-pressure control valve is still in the closed state, and the low-pressure fuel can circulate normally in the system.

[0062] Example 2

[0063] A diesel engine includes: a cylinder head 4 and a fuel tank, and also includes the uninterrupted fuel supply system for the injector involved in Example 1, the injector 2 is installed on the cylinder head 4, the injector pipe 204 and the cylinder head 4 are separated to form a cylinder oil return path 41, the cylinder head 4 is provided with a cylinder head oil return hole 42, the cylinder oil return path 41 is connected between the injector oil return hole 206 and the cylinder head oil return hole 42, and the cylinder head oil return hole 42 and the oil pump inlet return hole are respectively connected to the fuel tank.

[0064] When the roller 10 contacts the base circle 18, the direction of fuel flow is: fuel tank-oil pump oil inlet and return hole-oil pump low-pressure oil chamber 15-plunger oil inlet and return hole 17-compression oil chamber 16-oil pump oil outlet hole 12-high-pressure oil pipe 3-injector connecting pipe 204-injector body oil inlet oil path 207-needle valve oil inlet hole 214-low-pressure valve core control chamber 213-low-pressure control valve core oblique oil path 221-low-pressure control valve core annular oil path 222-needle valve return hole 215-injector body oil return path 220-spring chamber-injector oil return hole 206-cylinder body oil return path 41-cylinder head oil return hole 42-fuel tank.

[0065] When the roller 10 contacts the fuel supply cam 19, the direction of fuel flow is: fuel tank-fuel pump inlet and return hole-fuel pump low-pressure oil chamber 15-plunger oil inlet and return hole 17-compression oil chamber 16-fuel pump oil outlet hole 12-high-pressure oil pipe 3-injector connecting pipe 204-injector body oil inlet passage 207-needle valve oil inlet hole 214-low-pressure valve core control chamber 213-needle valve oil inlet passage 208-pressure accumulation chamber 210-nozzle 205.

[0066] Compared with the prior art, the present invention has the following advantages:

[0067] (1) Not only does the fuel injection pump 1 supply high-pressure fuel to the fuel injector 2 when pumping oil, but the fuel injection pump 1 also supplies low-pressure fuel to the fuel injector 2 when it is not working. The low-pressure fuel circulates. When the diesel engine is under low load, the low-pressure fuel heats the fuel injector 2. When the diesel engine is under high load, the low-pressure fuel flows inside the fuel injector 2, absorbing the heat of the fuel injector 2, reducing the temperature of the fuel injector 2 and improving the reliability of the fuel injector 2. Especially for heavy oil diesel engines, before the diesel engine is started, the low-pressure circulating oil preheats the fuel injector 2 in advance, and the heavy oil has good fluidity, ensuring the injection atomization effect of the heavy oil, and realizing the start and shutdown of the heavy oil;

[0068] (2) Fuel injection pump 1 has no oil outlet valve. High-pressure fuel exists only when pumping oil. The amount of high-pressure fuel in the system is greatly reduced, and the hydraulic vibration generated by the high-pressure fuel is also greatly reduced, thus improving system reliability.

[0069] (3) When low-pressure fuel circulates, low-pressure fuel always exists in the system, and oil pressure can be quickly built up when pumping oil.

[0070] The foregoing is an example of the best mode of carrying out the present invention. Any portion not described in detail herein is common knowledge within the skill of one of ordinary skill in the art. The scope of protection of the present invention is determined by the claims. Any equivalent transformation based on the technical teachings of the present invention is also within the scope of protection of the present invention.

Claims

1. An uninterrupted fuel supply system for a fuel injector, comprising: A fuel injection pump, the fuel injection pump comprising a pump body and a plunger pair disposed within the pump body, the pump body being provided with an oil pump inlet and return oil hole and an oil pump outlet oil hole, the plunger pair comprising a plunger and a plunger sleeve, the plunger sleeve and the pump body forming a low-pressure oil chamber of the oil pump, the oil pump inlet and return oil hole being in communication with the low-pressure oil chamber of the oil pump, the plunger and the plunger sleeve forming a compression oil chamber, the plunger sleeve being provided with a plunger inlet and return oil hole, the plunger inlet and return oil hole being used to connect the low-pressure oil chamber of the oil pump with the compression oil chamber; A fuel injector, the fuel injector comprising a fuel injector body, a needle valve disposed within the fuel injector body, and a needle valve return spring; the fuel injector body being provided with a fuel injector pipe, a nozzle, and a fuel injector oil return hole; a fuel injector body oil inlet passage and a needle valve oil inlet passage being provided between the fuel injector pipe and the nozzle; the needle valve being provided with a needle valve pressure surface, a pressure accumulator being provided at the needle valve pressure surface, the pressure accumulator being in communication with the needle valve oil inlet passage and the nozzle, respectively; The oil pump outlet and the injector pipe are connected via a high-pressure oil pipe. It is characterized by: The oil outlet hole of the oil pump is connected to the compression oil chamber; A low-pressure control valve is provided in the injector body, and the opening pressure of the low-pressure control valve is greater than the oil inlet pressure of the injection pump; When the pressure in the compression oil chamber exceeds the opening pressure of the low-pressure control valve, the low-pressure control valve opens, the injector body oil inlet passage and the needle valve oil inlet passage are connected, and the fuel in the compression oil chamber enters the pressure accumulation chamber through the high-pressure oil pipe, the injector body oil inlet passage, and the needle valve oil inlet passage in sequence. The fuel acts on the pressure surface of the needle valve. The force of the fuel acting on the pressure surface of the needle valve is greater than the force of the needle valve return spring on the needle valve, the needle valve rises, and the fuel in the pressure accumulation chamber is sprayed out through the nozzle. When the pressure of the compression oil chamber is lower than the opening pressure of the low-pressure control valve, the low-pressure control valve is closed, the oil inlet passage of the injector body is connected to the oil return hole of the injector, the low-pressure control valve is closed, and the fuel from the injection pump continuously flows into and out of the injector.

2. The uninterrupted fuel supply system for the fuel injector according to claim 1, characterized in that: The low-pressure control valve comprises a low-pressure control valve core and a low-pressure control valve core return spring; A low-pressure control valve core hole is provided at the end of the needle valve, and the low-pressure control valve core slides in the low-pressure control valve core hole. A low-pressure control valve core pressure surface is provided at one end of the low-pressure control valve core extending into the low-pressure control valve core hole. At the low-pressure control valve core pressure surface, the needle valve and the low-pressure control valve core form a low-pressure valve core control chamber. The needle valve is provided with a needle valve oil inlet hole for connecting the injector body oil inlet oil path and the low-pressure valve core control chamber. The low-pressure control valve core is provided with a low-pressure control valve core oil return oil path communicating with the low-pressure valve core control chamber, and the needle valve is provided with a needle valve oil return hole. The fuel in the compression oil chamber sequentially passes through the oil pump outlet, the high-pressure oil pipe, the injector pipe and the injector body oil inlet passage and enters the low-pressure valve core control chamber. When the force of the fuel acting on the pressure surface of the low-pressure control valve core is greater than the force of the low-pressure control valve core return spring on the low-pressure control valve core, the low-pressure control valve opens, the low-pressure control valve core rises, and the low-pressure valve core control chamber is connected to the needle valve oil inlet passage. The fuel in the low-pressure valve core control chamber enters the pressure accumulator chamber, pushing the needle valve to rise, and the fuel in the pressure accumulator chamber is sprayed out through the nozzle. When the force of the fuel acting on the pressure surface of the low-pressure control valve core is less than the force of the low-pressure control valve core return spring on the low-pressure control valve core, the low-pressure control valve core return oil circuit is connected with the needle valve return oil hole, and the needle valve return oil hole is connected with the injector return oil hole, and the fuel continuously flows into and out of the injector.

3. The uninterrupted fuel supply system for the fuel injector according to claim 2, characterized in that: The injector pipe extends into the injector body, the needle valve return spring is located between the first needle valve spring seat and the second needle valve spring seat, the first needle valve spring seat rests on the injector pipe, and the low-pressure control valve core return spring is located between the low-pressure control valve core and the second needle valve spring seat.

4. The uninterrupted fuel supply system for the fuel injector according to claim 3, characterized in that: The low-pressure control valve core return spring is located between the low-pressure control valve core spring seat and the low-pressure control valve core, and the low-pressure control valve core spring seat abuts against the second needle valve spring seat.

5. The uninterrupted fuel supply system for the fuel injector according to claim 4, characterized in that: The injector body is provided with a spring cavity, wherein the first needle valve spring seat, the needle valve return spring, the second needle valve spring seat, the low-pressure control valve core spring seat and the low-pressure control valve core return spring are all located in the spring cavity; The injector body is provided with an injector body oil return path, the injector body oil return path is communicated between the spring chamber and the needle valve oil return hole, and the spring chamber is communicated with the injector oil return hole.

6. The uninterrupted fuel supply system for the fuel injector according to claim 5, characterized in that: The low-pressure control valve core oil return oil circuit includes a low-pressure control valve core oblique oil circuit and a low-pressure control valve core annular oil circuit that are connected; When the low-pressure control valve is closed, the annular oil path of the low-pressure control valve core is communicated with the oil return hole of the needle valve.

7. The uninterrupted fuel supply system for the fuel injector according to claim 1, characterized in that: The needle valve lift is H1, H1 = (0.5-0.7) mm.

8. The uninterrupted fuel supply system for fuel injectors according to claim 2, characterized in that: The diameter of the oil return hole of the needle valve is R, R=(1-1.5) mm, and the lift of the low-pressure control valve core is H2, H2=(2-2.5) mm.

9. The uninterrupted fuel supply system for the fuel injector according to claim 2, characterized in that: The opening pressure of the low-pressure control valve core is F1, and the pressure of the low-pressure oil chamber of the oil pump is F2. 2.8F2≤F1≤3.2F2.

10. A diesel engine comprising: The cylinder head and the fuel tank are characterized in that they further include the uninterrupted fuel supply system of the injector according to any one of claims 1 to 9, the injector is installed on the cylinder head, the injector pipe and the cylinder head are spaced apart to form a cylinder oil return circuit, the cylinder head is provided with a cylinder head oil return hole, the cylinder oil return circuit is connected between the injector oil return hole and the cylinder head oil return hole, and the cylinder head oil return hole and the oil pump inlet and return hole are respectively connected to the fuel tank.

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