High-pressure common rail fuel system, high-pressure common rail control method and engine system

Abstract

The invention belongs to the technical field of engines, and discloses a high-pressure common rail fuel system, a high-pressure common rail control method and an engine system. The high-pressure common-rail fuel system comprises a high-pressure common-rail pipe, an oil tank, a coarse filter, an oil delivery pump, a fine filter and an oil injection pump, the oil tank, the coarse filter, the oil delivery pump, the fine filter and the oil injection pump are sequentially communicated, an oil outlet of the oil injection pump can be selectively connected and disconnected with the high-pressure common-rail pipe, and an oil return opening of the oil injection pump can be selectively communicated with an oil inlet of the oil tank or the coarse filter. By the adoption of the high-pressure common rail control method, the phenomenon that negative pressure air suction is generated in the coarse strainer can be effectively improved, and the problem of engine flameout caused by difficult rail pressure building can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of engine technology, and in particular to a high-pressure common rail fuel system, a high-pressure common rail control method and an engine system. Background Art

[0002] The high-pressure common rail fuel system includes a low-pressure oil circuit and a high-pressure oil circuit. The low-pressure oil circuit is generally at negative pressure, and the high-pressure oil circuit is generally at positive pressure. The fuel in the low-pressure oil circuit is filtered through a coarse filter and a fine filter and pumped into the high-pressure oil pump through an oil transfer pump. The high-pressure oil pump then pumps the high-pressure oil into the common rail pipe. The common rail pipe is connected to the injectors of each cylinder of the engine through a high-pressure oil pipe, and fuel is sprayed into the engine cylinder body through the injectors.

[0003] At present, in order to solve the problem of difficulty in building rail pressure and easy flameout during the engine startup phase caused by gas in the low-pressure oil circuit, the existing technology usually sets an exhaust structure in the low-pressure oil circuit and / or sets an exhaust hole on the coarse filter. However, when the exhaust structure on the low-pressure oil circuit and the exhaust hole on the coarse filter are abnormal and cannot be exhausted, the gas will still accumulate in the coarse filter, resulting in negative pressure gas evolution in the coarse filter, which will eventually cause the engine to flame out; when the engine is stopped, the gas on the outside of the filter element cannot be discharged due to the negative pressure on the inside of the filter element of the coarse filter. As the gas continues to accumulate, the liquid level on the outside of the filter element continues to drop, and the liquid level difference between the inside and outside of the filter element increases. After the engine is turned off, the air on the outside of the filter element will enter the inside of the filter element. When the engine is started again, the gas on the inside of the filter element will be discharged first to form a continuous gas column, resulting in the oil pump being unable to pump oil normally, which will cause the engine to still flame out. Summary of the invention

[0004] The object of the present invention is to provide a high pressure common rail fuel system, a high pressure common rail control method and an engine system to solve the above problems existing in the high pressure common rail fuel system in the prior art.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A high-pressure common rail fuel system comprises a high-pressure common rail pipe, and a fuel tank, a coarse filter, a fuel pump, a fine filter and a fuel injection pump which are connected in sequence. The oil outlet of the fuel injection pump can be selectively connected and disconnected with the high-pressure common rail pipe, and the oil return port of the fuel injection pump can be selectively connected to the oil inlet of the fuel tank or the coarse filter.

[0007] As a preferred solution of the above-mentioned high-pressure common rail fuel system, the high-pressure common rail fuel system further includes a control valve, which can selectively connect the oil return port of the injection pump with the oil inlet of the fuel tank or the coarse filter.

[0008] As a preferred solution of the above-mentioned high-pressure common rail fuel system, the control valve is a two-position three-way solenoid valve, the input port of the two-position three-way solenoid valve is connected to the oil return port of the injection pump, one output port of the two-position three-way solenoid valve is connected to the fuel tank, and the other output port of the two-position three-way solenoid valve is connected to the oil inlet of the coarse filter.

[0009] As a preferred solution of the above-mentioned high-pressure common rail fuel system, the control valve includes two solenoid switch valves; the input ports of the two solenoid switch valves are both connected to the oil return port of the injection pump, the output port of one of the solenoid switch valves is connected to the oil inlet of the coarse filter, and the output port of the other solenoid switch valve is connected to the fuel tank.

[0010] A high-pressure common rail control method is used to be implemented in the above-mentioned high-pressure common rail fuel system, and the high-pressure common rail control method includes:

[0011] After T15 is powered on, the working mode is determined according to the T15 power-on status and engine speed;

[0012] Controlling the high pressure common rail fuel system to operate according to a determined working mode;

[0013] The working mode includes a first working mode and a second working mode;

[0014] The first working mode is: the oil return port of the fuel injection pump is connected to the oil inlet of the coarse filter;

[0015] The second working mode is that the oil return port of the fuel injection pump is connected to the fuel tank.

[0016] As a preferred solution of the above-mentioned high-pressure common rail control method, the step of determining the working mode according to the T15 power-on state and the engine speed includes:

[0017] Real-time judgment of whether the T15 power-on state is changed to the T15 power-off state;

[0018] If the T15 power-on state is changed to the T15 power-off state, the working mode is determined to be the first working mode.

[0019] As a preferred solution of the above-mentioned high-pressure common rail control method, when the T15 power-on state is changed to the T15 power-off state, the oil outlet of the fuel injection pump is controlled to be disconnected from the high-pressure common rail pipe.

[0020] As a preferred solution of the above high pressure common rail control method, the step of determining the working mode according to the T15 power-on state and the engine speed also includes:

[0021] Before the engine is started, determining that the working mode is a default working mode; the default working mode is the first working mode or the second working mode;

[0022] After the engine is started, it is determined in real time whether the engine speed is within the set critical speed range;

[0023] If the engine speed is within the set critical speed range, the current working mode is maintained unchanged;

[0024] If the engine speed is less than the minimum value of the set critical speed range, determining the working mode to be the first working mode;

[0025] If the engine speed is greater than the maximum value of the set critical speed range, the operating mode is determined to be the second operating mode.

[0026] As a preferred solution of the above-mentioned high-pressure common rail control method, when the engine is started, the oil outlet of the fuel injection pump is controlled to be connected to the high-pressure common rail pipe.

[0027] An engine system includes the above-mentioned high-pressure common rail fuel system.

[0028] Beneficial effects of the present invention:

[0029] The present invention provides a high-pressure common rail fuel system, including a high-pressure common rail pipe, and a fuel tank, a coarse filter, a fuel pump, a fine filter and a fuel injection pump connected in sequence, the fuel outlet of the fuel injection pump can be selectively connected and disconnected with the high-pressure common rail pipe, and the fuel return port of the fuel injection pump can be selectively connected with the fuel tank or the fuel inlet of the coarse filter. By adopting the high-pressure common rail fuel system, the phenomenon of negative pressure suction in the coarse filter can be effectively improved, and the problem of engine flameout caused by difficulty in rail pressure building can be effectively improved.

[0030] The present invention also provides a high-pressure common rail control method for implementation in the above-mentioned high-pressure common rail fuel system. The high-pressure common rail control method includes: after T15 is powered on, the working mode is determined according to the power-on state of T15 and the engine speed; the high-pressure common rail fuel system is controlled to operate according to the determined working mode; the working mode includes a first working mode and a second working mode; the first working mode is: the oil return port of the injection pump is connected to the oil inlet of the coarse filter; the second working mode is: the oil return port of the injection pump is connected to the fuel tank. By adopting the high-pressure common rail control method to control the above-mentioned high-pressure common rail fuel system, the phenomenon of negative pressure suction in the coarse filter can be effectively improved, and the problem of engine stalling caused by difficulty in building rail pressure can be effectively improved.

[0031] The present invention also provides an engine system, comprising the above-mentioned high-pressure common rail fuel system. By adopting the above-mentioned high-pressure common rail fuel system, the working reliability of the engine system can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1The principle of the high pressure common rail fuel system provided by the specific embodiment of the present invention is Figure 1 ;

[0033] Figure 2 The principle of the high pressure common rail fuel system provided by the specific embodiment of the present invention is Figure 2 ;

[0034] Figure 3 The process of the high pressure common rail control method provided by the specific embodiment of the present invention is Figure 1 ;

[0035] Figure 4 The process of the high pressure common rail control method provided by the specific embodiment of the present invention is Figure 2 ;

[0036] Figure 5 The process of the high pressure common rail control method provided by the specific embodiment of the present invention is Figure 3 .

[0037] In the figure:

[0038] 1. Fuel tank; 2. Coarse filter; 3. Fuel transfer pump; 4. Fine filter; 5. Fuel injection pump; 61. Two-position three-way solenoid valve; 62. Solenoid switch valve. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0040] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0042] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0043] The present invention provides a high pressure common rail fuel system, such as Figure 1 and Figure 2 As shown, it includes a high-pressure common rail pipe, and a fuel tank 1, a coarse filter 2, a fuel pump 3, a fine filter 4 and a fuel injection pump 5 which are connected in sequence. The oil outlet of the fuel injection pump 5 can be selectively connected and disconnected with the high-pressure common rail pipe, and the oil return port of the fuel injection pump 5 can be selectively connected with the fuel tank 1 or the oil inlet of the coarse filter 2.

[0044] The present invention also provides a high pressure common rail control method for implementing the above-mentioned high pressure common rail fuel system. Figure 3-5 As shown, the high pressure common rail control method includes:

[0045] After S100 and T15 are powered on, the working mode is determined according to the power-on status of T15 and the engine speed.

[0046] The working mode includes a first working mode and a second working mode.

[0047] The first working mode is that the oil return port of the fuel injection pump 5 is connected to the oil inlet of the coarse filter 2 .

[0048] The second working mode is: the oil return port of the fuel injection pump 5 is connected to the fuel tank 1 .

[0049] Specifically, Figure 3 and Figure 4 As shown, step S100 includes:

[0050] S111 , determining in real time whether the T15 power-on state is changed to the T15 power-off state.

[0051] If the T15 power-on state is changed to the T15 power-off state, the working mode is determined to be the first working mode. Step S210 is executed, and step S112 is executed simultaneously.

[0052] Specifically, the transition from the T15 power-on state to the T15 power-off state refers to: directly transitioning from the T15 power-on state to the T15 power-off state; or directly transitioning from the engine low-speed running state to the T15 power-off state after the engine is started; or directly transitioning from the engine high-speed running state to the T15 power-off state after the engine is started. That is, directly transitioning from any state after T15 power-on to the T15 power-off state.

[0053] S112, controlling the oil outlet of the fuel injection pump 5 to be disconnected from the high pressure common rail pipe, and no longer spraying fuel into the engine cylinder.

[0054] Specifically, Figure 3 and Figure 5 As shown, step S100 also includes:

[0055] S121: Before the engine is started, determine that the working mode is a default working mode, which is the first working mode or the second working mode.

[0056] It is understandable that after T15 is powered on and before the engine is started, the injector does not need to spray fuel into the engine cylinder, the oil outlet of the injection pump 5 is disconnected from the high-pressure common rail pipe, and the fuel in the high-pressure common rail fuel system does not flow. Therefore, at this time, the oil return port of the injection pump 5 is connected to the oil inlet of the coarse filter 2, or the oil return port of the injection pump 5 is connected to the fuel tank 1.

[0057] Optionally, after T15 is powered on and before the engine is started, the working mode is determined to be the first working mode. Execute step S210. In this way, the working mode of the high-pressure common rail fuel system after T15 is powered on and before the engine is started is the same as the working mode of the high-pressure common rail fuel system when the engine speed is less than the minimum value of the set critical speed range, thereby reducing the number of times the working mode is switched. As an alternative, after T15 is powered on and before the engine is started, the working mode is determined to be the second working mode. Step S220.

[0058] S122: When the engine is started, the fuel outlet of the fuel injection pump 5 is controlled to be connected to the high-pressure common rail pipe, so that fuel can be sprayed into the engine cylinder.

[0059] S123: After the engine is started, determine in real time whether the engine speed is within a set critical speed range.

[0060] If the engine speed is within the set critical speed range, the current working mode remains unchanged.

[0061] If the engine speed is less than the minimum value of the set critical speed range, the operating mode is determined to be the first operating mode. Step S210 is executed.

[0062] If the engine speed is greater than the maximum value of the set critical speed range, the operating mode is determined to be the second operating mode. Step S220 is executed.

[0063] It can be understood that if the engine speed is always less than the minimum value of the set critical speed range, it is determined that the working mode of the high-pressure common rail fuel system is always the first working mode.

[0064] If the engine speed is always greater than the maximum value of the set critical speed range, it is determined that the operating mode of the high-pressure common rail fuel system is always the second operating mode.

[0065] If the engine speed decreases from a value greater than the maximum value of the critical speed range to a value within the set critical speed range, the operating mode is maintained at the second operating mode; when the engine speed further decreases to a value less than the minimum value of the set critical speed range, the operating mode is determined to be the first operating mode.

[0066] If the engine speed increases from a value less than the minimum value of the critical speed range to a value within the set critical speed range, the operating mode is maintained at the first operating mode; when the engine speed further increases to a value greater than the maximum value of the set critical speed range, the operating mode is determined to be the second operating mode.

[0067] This arrangement can avoid the high-pressure common rail fuel system from frequently switching working modes, thereby effectively improving the service life of various components in the high-pressure common rail fuel system.

[0068] The critical speed range is set as an empirical range obtained from a large number of previous tests, or the critical speed range is set as a set range set according to the working requirements of the engine system.

[0069] Specifically, in this embodiment, the exemplary setting critical speed range is: 1000r / min ~ 1100r / min.

[0070] S200. Control the high-pressure common rail fuel system to operate according to a determined working mode.

[0071] Specifically, when the determined working mode is the first working mode, step S210 is executed: controlling the common rail fuel system to operate in the first working mode, that is, controlling the oil return port of the fuel injection pump 5 to communicate with the oil inlet of the coarse filter 2 .

[0072] Specifically, when the determined working mode is the second working mode, step S220 is executed: controlling the common rail fuel system to operate in the second working mode, that is, controlling the oil return port of the fuel injection pump 5 to communicate with the fuel tank 1 .

[0073] Specifically, when T15 is powered on and the engine is in the engine starting state or the engine low speed running state, that is, when the engine speed is less than the minimum value of the set critical speed range, the oil outlet of the injection pump 5 is connected to the high pressure common rail pipe, the speeds of the fuel delivery pump 3 and the injection pump 5 are both relatively small, and the amount of fuel delivered to the injector through the high pressure common rail pipe by the injection pump 5 and injected into the engine cylinder is relatively small, which is much less than the amount of fuel supplied to the injection pump 5 by the fuel tank 1. Therefore, most of the fuel flowing into the injection pump 5 will flow back from the oil return port of the injection pump 5 and the pressure of this part of the fuel flowing out of the oil return port of the injection pump 5 is positive pressure. Therefore, when the engine is in the engine starting state or the engine low speed running state, the oil return port of the injection pump 5 is controlled to be connected to the oil inlet of the coarse filter 2, so that the coarse filter 2, the fuel delivery pump 3, the fine filter 4 and the injection pump 5 are connected in sequence and form a circulation loop, so that the fuel with positive pressure flowing out of the oil return port of the injection pump 5 flows into the coarse filter 2 to replenish the coarse filter 2, so that The coarse filter 2 becomes a positive pressure environment to avoid the accumulation of air precipitated in the coarse filter 2. When the coarse filter 2 is filled with fuel, the negative pressure suction phenomenon in the coarse filter 2 can be effectively avoided. After the fuel with positive pressure flowing out of the return port of the fuel injection pump 5 flows into the coarse filter 2, it flows through the fuel delivery pump 3, the fine filter 4 and the fuel injection pump 5 in sequence, thereby effectively increasing the oil pressure of the oil circuit from the coarse filter 2 to the fuel injection pump 5, promoting the flow of fuel, promoting the fuel delivery pump 3 to suck oil and promoting the fuel injection pump 5 to suck oil, thereby effectively improving the problem of engine stalling caused by the difficulty in rail pressure building when the engine is started or the engine is running at a low speed; secondly, since the fuel pressure flowing out of the return port of the fuel injection pump 5 is positive, even if there is air in the coarse filter 2, this part of the fuel flowing into the coarse filter 2 can also disperse the air in the coarse filter 2, so that the air is dispersed and circulated in the high-pressure common rail fuel system, thereby effectively avoiding the problem of engine stalling caused by the generation of air columns in the coarse filter 2.

[0074] It is understandable that before the primary filter 2 is filled with fuel, the fuel with positive pressure flowing out through the oil return port of the fuel injection pump 5 breaks up the air in the primary filter 2, thereby effectively avoiding the phenomenon of engine stalling caused by the air column generated in the primary filter 2. When the primary filter 2 is filled with fuel, the phenomenon of negative pressure air intake in the primary filter 2 can be directly avoided. When the engine is in the engine starting state or the engine low speed running state, the oil pressure of the oil circuit from the primary filter 2 to the fuel injection pump 5 can be effectively increased, thereby effectively improving the problem of engine stalling caused by the difficulty of rail pressure building when the engine is in the engine starting state or the engine low speed running state.

[0075] Specifically, the engine running state also includes the engine high speed running state. It is understandable that after starting, the engine low speed running state and the engine high speed running state can be switched repeatedly. The critical speed range is set as the dividing speed range between the engine low speed running and the engine high speed running.

[0076] When the engine changes from low-speed operation to high-speed operation, that is, the engine speed is greater than the maximum value of the set critical speed range, it indicates that the oil pressure in the oil circuit from the coarse filter 2 to the fuel injection pump 5 meets the oil pressure requirement during normal operation of the engine system, and there is no need to continue to transport fuel to the coarse filter 2 through the return oil port of the fuel injection pump 5 to increase the oil pressure in the oil circuit from the coarse filter 2 to the fuel injection pump 5. The return oil port of the fuel injection pump 5 is controlled to be connected with the fuel tank 1, so that the fuel tank 1, the coarse filter 2, the fuel pump 3, the fine filter 4 and the fuel injection pump 5 are connected in sequence to form a circulation loop.

[0077] When T15 is powered on and the power-on state of T15 is changed to the power-off state of T15, the injector no longer needs to inject fuel into the engine cylinder, and the oil outlet of the fuel injection pump 5 is controlled to be disconnected from the high-pressure common rail pipe, and all the fuel flowing into the fuel injection pump 5 flows out from the oil return port of the fuel injection pump 5. Therefore, when the power-on state of T15 is changed to the power-off state of T15, the oil return port of the fuel injection pump 5 is controlled to be connected with the oil inlet of the coarse filter 2, so that the coarse filter 2, the fuel delivery pump 3, the fine filter 4 and the fuel injection pump 5 are connected in sequence to form a circulation loop, and the fuel injection pump 5 is controlled to be connected with the oil inlet of the coarse filter 2. The fuel with positive pressure flowing out of the oil return port of the pump 5 flows into the coarse filter 2 to replenish the coarse filter 2, so that the amount of fuel in the coarse filter 2 is large or even the coarse filter 2 is filled with fuel, thereby effectively improving the phenomenon of negative pressure suction in the coarse filter 2 when the engine is started next time, and effectively improving the problem of difficulty in building rail pressure due to poor low-pressure fuel supply when the engine is started next time, thereby further reducing the phenomenon of engine stalling due to negative pressure suction and / or difficulty in building rail pressure after the next engine is started.

[0078] Therefore, by adopting the above-mentioned high-pressure common rail control method to control the above-mentioned high-pressure common rail fuel system, the phenomenon of negative pressure intake in the coarse filter 2 can be effectively improved, and the problem of engine stalling caused by difficulty in building rail pressure can be effectively improved.

[0079] It is understandable that after the engine is started, since the fuel injector will spray fuel into the engine cylinder, the coarse filter 2 will suck fuel from the fuel tank 1 under the negative pressure of the fuel pump 3 to replenish the fuel.

[0080] Among them, T15 power-on means that the vehicle's ignition switch or key switch is in the "ON" position. It means that the vehicle's electrical system has been started, the main circuits have been energized, and the vehicle can operate electrical equipment such as starting and lighting. In diesel vehicles, T15 power-on means that a specific circuit or configuration has been energized. The specific circuit and configuration are related to the vehicle model and will not be repeated here.

[0081] Among them, engine starting refers to the process of the engine changing from a stationary state to a running state.

[0082] The high-pressure common rail fuel system further includes a control valve, which can selectively connect the oil return port of the fuel injection pump 5 to the oil inlet of the fuel tank 1 or the coarse filter 2 .

[0083] Specifically, Figure 1 As shown, the control valve is a two-position three-way solenoid valve 61, the input port of the two-position three-way solenoid valve 61 is connected to the oil return port of the fuel injection pump 5, one output port of the two-position three-way solenoid valve 61 is connected to the fuel tank 1, and the other output port of the two-position three-way solenoid valve 61 is connected to the oil inlet of the coarse filter 2. In this way, the oil return port of the fuel injection pump 5 can be selectively connected to the fuel tank 1 or the oil inlet of the coarse filter 2.

[0084] Furthermore, when the two-position three-way solenoid valve 61 is energized, the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the oil inlet port of the coarse filter 2, and the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 with the fuel tank 1; when the two-position three-way solenoid valve 61 is de-energized, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 with the oil inlet port of the coarse filter 2, and the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the fuel tank 1. As an alternative solution, when the two-position three-way solenoid valve 61 is energized, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the oil inlet port of the coarse filter 2, and the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the fuel tank 1; when the two-position three-way solenoid valve 61 is de-energized, the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the oil inlet port of the coarse filter 2, and the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the fuel tank 1.

[0085] From the perspective of further improving the negative pressure suction phenomenon in the coarse filter 2, it is preferred that when the two-position three-way solenoid valve 61 is energized, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the oil inlet of the coarse filter 2, and connects the oil return port of the fuel injection pump 5 with the fuel tank 1; when the two-position three-way solenoid valve 61 is de-energized, the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the oil inlet of the coarse filter 2, and disconnects the oil return port of the fuel injection pump 5 from the fuel tank 1. When the engine is started next time, the fuel flowing out of the oil return port of the fuel injection pump 5 directly flows into the coarse filter 2 to further replenish the coarse filter 2, so that the negative pressure suction phenomenon in the coarse filter 2 can be further improved when the engine is started next time, and the problem of rail pressure building difficulty caused by poor low-pressure fuel supply when the engine is started next time can be further improved.

[0086] From the perspective of saving energy consumption of the control valve and improving the service life of the control valve, it is preferred that when the two-position three-way solenoid valve 61 is energized, the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the oil inlet of the coarse filter 2, and the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the fuel tank 1; when the two-position three-way solenoid valve 61 is de-energized, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the oil inlet of the coarse filter 2, and the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the fuel tank 1. After the vehicle is started, the duration of the engine in the high-speed running state is usually longer than the total duration of the engine in the starting state and the low-speed running state, so such a setting can save energy consumption of the control valve and improve the service life of the control valve.

[0087] In this embodiment, for example, when the two-position three-way solenoid valve 61 is powered, the two-position three-way solenoid valve 61 connects the oil return port of the fuel injection pump 5 with the oil inlet of the coarse filter 2, and disconnects the oil return port of the fuel injection pump 5 from the fuel tank 1; when the two-position three-way solenoid valve 61 is powered off, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the oil inlet of the coarse filter 2, and connects the oil return port of the fuel injection pump 5 with the fuel tank 1. Then, when the vehicle ECU is powered off, the two-position three-way solenoid valve 61 is powered off, the two-position three-way solenoid valve 61 disconnects the oil return port of the fuel injection pump 5 from the oil inlet of the coarse filter 2, and connects the oil return port of the fuel injection pump 5 with the fuel tank 1.

[0088] Specifically, the two-position three-way solenoid valve 61 and the fuel injection pump 5 are both electrically connected to the vehicle ECU.

[0089] Specifically, in this embodiment, when the T15 power-on state is changed to the T15 power-off state and the vehicle ECU is powered off, the two-position three-way solenoid valve 61 loses power, and the working mode of the high-pressure common rail fuel system is automatically changed to the second working mode.

[0090] As an alternative, Figure 2 As shown, the control valve includes two electromagnetic switch valves 62; the input ports of the two electromagnetic switch valves 62 are both connected to the oil return port of the fuel injection pump 5, the output port of one electromagnetic switch valve 62 is connected to the oil inlet of the coarse filter 2, and the output port of the other electromagnetic switch valve 62 is connected to the fuel tank 1. It is also possible to selectively connect the oil return port of the fuel injection pump 5 to the oil inlet of the fuel tank 1 or the coarse filter 2. Both electromagnetic switch valves 62 are electrically connected to the vehicle ECU.

[0091] Specifically, the two electromagnetic switch valves 62 are respectively a first electromagnetic switch valve and a second electromagnetic switch valve. The output port of the first electromagnetic switch valve is communicated with the oil inlet of the coarse filter 2. The output port of the second electromagnetic switch valve is communicated with the oil tank 1.

[0092] Further, when the first electromagnetic switch valve is energized, the input end of the first electromagnetic switch valve is connected to the output end of the first electromagnetic switch valve; when the first electromagnetic switch valve is de-energized, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are disconnected. When the second electromagnetic switch valve is energized, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are disconnected; when the second electromagnetic switch valve is de-energized, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are connected. As an alternative, when the first electromagnetic switch valve is energized, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are disconnected; when the first electromagnetic switch valve is de-energized, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are connected. When the second electromagnetic switch valve is energized, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are connected; when the second electromagnetic switch valve is de-energized, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are disconnected.

[0093] From the perspective of further improving the negative pressure suction phenomenon in the coarse filter 2, it is preferred that when the first electromagnetic switch valve is powered, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are disconnected; when the first electromagnetic switch valve is de-energized, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are connected. When the second electromagnetic switch valve is powered, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are connected; when the second electromagnetic switch valve is de-energized, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are disconnected.

[0094] From the perspective of saving energy consumption of the control valve and improving the service life of the control valve, it is preferred that when the first electromagnetic switch valve is powered, the input end of the first electromagnetic switch valve is connected to the output end of the first electromagnetic switch valve; when the first electromagnetic switch valve is powered off, the input end of the first electromagnetic switch valve and the output end of the first electromagnetic switch valve are disconnected. When the second electromagnetic switch valve is powered, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are disconnected; when the second electromagnetic switch valve is powered off, the input end of the second electromagnetic switch valve and the output end of the second electromagnetic switch valve are connected.

[0095] Preferably, the fuel delivery pump 3 is integrated with the fuel injection pump 5, so as to improve the integration of the high-pressure common rail fuel system.

[0096] Specifically, the oil delivery pump 3 is a mechanical pump. The specific structure of the oil delivery pump 3 belongs to the prior art and will not be described in detail here. The specific structures of the coarse filter 2 and the fine filter 4 also belong to the prior art and will not be described in detail here.

[0097] The present invention also provides an engine system, comprising the above-mentioned high-pressure common rail fuel system. By adopting the above-mentioned high-pressure common rail fuel system, the working reliability of the engine system can be effectively improved.

[0098] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A high-pressure common rail fuel system, comprising a high-pressure common rail pipe, and a fuel tank (1), a coarse filter (2), a fuel pump (3), a fine filter (4) and a fuel injection pump (5) connected in sequence, wherein the fuel outlet of the fuel injection pump (5) can be selectively connected and disconnected with the high-pressure common rail pipe, characterized in that: The oil return port of the fuel injection pump (5) can be selectively connected to the oil inlet of the fuel tank (1) or the coarse filter (2).

2. The high pressure common rail fuel system according to claim 1, characterized in that: The high-pressure common rail fuel system also includes a control valve, which can selectively connect the oil return port of the fuel injection pump (5) to the oil inlet of the fuel tank (1) or the coarse filter (2).

3. The high pressure common rail fuel system according to claim 2, characterized in that: The control valve is a two-position three-way solenoid valve (61), the input port of the two-position three-way solenoid valve (61) is connected to the oil return port of the fuel injection pump (5), one output port of the two-position three-way solenoid valve (61) is connected to the fuel tank (1), and the other output port of the two-position three-way solenoid valve (61) is connected to the oil inlet of the coarse filter (2).

4. The high pressure common rail fuel system according to claim 2, characterized in that: The control valve comprises two electromagnetic switch valves (62); the input ports of the two electromagnetic switch valves (62) are both connected to the oil return port of the fuel injection pump (5), the output port of one of the electromagnetic switch valves (62) is connected to the oil inlet of the coarse filter (2), and the output port of the other electromagnetic switch valve (62) is connected to the fuel tank (1).

5. A high pressure common rail control method, characterized in that: For use in the high-pressure common rail fuel system according to any one of claims 1 to 4, the high-pressure common rail control method comprises: After T15 is powered on, the working mode is determined according to the T15 power-on status and engine speed; Controlling the high pressure common rail fuel system to operate according to a determined working mode; The working mode includes a first working mode and a second working mode; The first working mode is: the oil return port of the fuel injection pump (5) is connected to the oil inlet port of the coarse filter (2); The second working mode is that the oil return port of the fuel injection pump (5) is connected to the fuel tank (1).

6. The high pressure common rail control method according to claim 5, characterized in that: The steps of determining the working mode according to the T15 power-on state and the engine speed include: Real-time judgment of whether the T15 power-on state is changed to the T15 power-off state; If the T15 power-on state is changed to the T15 power-off state, the working mode is determined to be the first working mode.

7. The high pressure common rail control method according to claim 6, characterized in that: When the T15 power-on state is changed to the T15 power-off state, the oil outlet of the fuel injection pump (5) is controlled to be disconnected from the high-pressure common rail pipe.

8. The high pressure common rail control method according to any one of claims 6 to 7, characterized in that: The step of determining the working mode according to the T15 power-on state and the engine speed also includes: Before the engine is started, determining that the working mode is a default working mode; the default working mode is the first working mode or the second working mode; After the engine is started, it is determined in real time whether the engine speed is within the set critical speed range; If the engine speed is within the set critical speed range, the current working mode is maintained unchanged; If the engine speed is less than the minimum value of the set critical speed range, determining the working mode to be the first working mode; If the engine speed is greater than the maximum value of the set critical speed range, the operating mode is determined to be the second operating mode.

9. The high pressure common rail control method according to any one of claims 6 to 7, characterized in that: When the engine is started, the oil outlet of the fuel injection pump (5) is controlled to communicate with the high-pressure common rail pipe.

10. An engine system, characterized in that A high-pressure common rail fuel system comprising any one of claims 1 to 4.

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