Electronic unit pump and oil supply control method thereof

Abstract

The invention discloses an electronic unit pump and an oil supply control method thereof.The electronic unit pump comprises a pump body, a valve body, a push rod and the like, a roller is installed on the push rod and controlled by an oil pumping cam, and the valve body is at least provided with a first drainage channel and a second drainage channel which are communicated with a main oil channel; the valve body is at least provided with a first electromagnetic valve used for controlling the first drainage channel to be connected and disconnected and a second electromagnetic valve used for controlling the second drainage channel to be connected and disconnected. By controlling the opening and closing moments of the first electromagnetic valve and the second electromagnetic valve, the three-section fuel injection requirement of the engine in the diesel engine state of'pilot injection, main injection and post injection 'can be met, the fuel supply requirement of the micro-injection gas engine can also be met, and the engine can be restored to the full-power diesel engine state to operate after gas fuel is used up.

Description

Technical Field

[0001] The present invention relates to the technical field of engine fuel supply systems, and in particular to an electronically controlled unit pump and a method for controlling fuel supply using the pump. Background Art

[0002] When the diesel engine fuel supply system is performing fuel injection, it is hoped that the three stages of pre-injection (or boot injection), main injection, and post-injection can be achieved to improve engine performance and reduce emissions. Figure 1 or Figure 2 As shown. The high-pressure common rail fuel supply system has a stable fuel pressure in the rail pipe, and controls the fuel injection amount by the opening time of the solenoid valve. The control accuracy is high and can meet the requirements of the three stages of engine pre-injection, main injection and post-injection.

[0003] The micro-injection pilot dual-fuel engine with a diesel engine as the main body refers to a micro amount of diesel (1% to 5% of the full load fuel volume) as the pilot fuel, which is injected into the cylinder for compression ignition and then ignites the main gas fuel to do work. Since the fuel is the ignition energy of the gas fuel, the amount of fuel injection per cycle directly determines the combustion characteristics of the gas fuel, thereby affecting the performance of the engine. Therefore, the supply control accuracy of the small amount of fuel injected is very high. The high-pressure common rail fuel supply system has a stable fuel pressure in the rail pipe, and the fuel injection amount is controlled by the opening time of the solenoid valve. The control accuracy is high and can meet the micro-injection pilot fuel supply requirements.

[0004] However, the traditional fuel supply system based on electronically controlled unit pump cannot meet the three-stage injection requirements of diesel engines and the small oil injection requirements of micro-injection ignition dual-fuel engines.

[0005] The traditional electronically controlled single pump fuel supply system usually includes a cam, an oil pumping system, a solenoid valve, a high-pressure oil pipe, and a fuel injector. The cam drives the roller to drive the plunger to reciprocate and pressurize the diesel to the high-pressure chamber. When the electromagnet is not energized, the sealing cone surface is not in contact, and the diesel in the high-pressure chamber leaks through the gap of the sealing cone surface. The diesel in the high-pressure oil pipe does not build up high pressure and cannot drive the fuel injector to open, so the fuel injector does not spray fuel. When the solenoid valve is energized, the sealing cone surface is in contact, the diesel pressure in the high-pressure chamber increases, and enters the fuel injector through the high-pressure oil pipe. After the diesel pressure reaches the opening pressure of the injector, the injector opens to spray the diesel into the cylinder. When the solenoid valve is de-energized again, the sealing cone surface opens to release pressure under the action of the spring force, and the fuel injector stops spraying fuel.

[0006] During the cam oil pumping process, the time from the closing to the opening of the solenoid valve can be controlled to control the amount of oil supplied per cycle of the single pump. Under certain speed conditions, the time t from the closing to the opening of the solenoid valve corresponds to the cam angle α. If the system meets the requirements of the micro-injection engine and the injection amount is to reach 1% to 5% of the full load oil amount, the corresponding cam angle β must be quite small when running in the micro-injection state. For example, at a certain engine speed, the time from the closing to the opening of the corresponding solenoid valve is 2 milliseconds, and the corresponding time requirement for micro-injection is less than 0.2 milliseconds, which far exceeds the response time requirement of the solenoid valve.

[0007] High-pressure common rail fuel supply systems have been widely used in diesel engines with power below 500KW. For large engines with power greater than 1000KW, the cost of the matching high-pressure common rail fuel supply system has soared significantly due to changes in process and structure, and the price has increased by more than ten times, which has limited its application. Therefore, most large diesel engines still use electronically controlled single pump fuel supply systems.

[0008] Some manufacturers' micro-injection engines adopt the solution of matching with a small high-pressure common rail fuel system. For example, for a 1000KW engine, the matching high-pressure common rail system can only meet the diesel supply demand of 300KW. This solution solves the problem of fuel supply system cost (small high-pressure common rail system has low cost) and control accuracy in the micro-injection state. However, when the gas fuel is used up, it cannot be restored to the full-power diesel engine state (it can only be restored to the 300Kw diesel engine state), which limits its application. Summary of the invention

[0009] In view of this, the present invention provides an electronically controlled single pump. As the same concept, the present invention also provides a method for controlling fuel supply using the pump, which can realize the three-stage fuel injection requirements of "pre-injection, main injection, and post-injection" of the engine in the diesel engine state, and can also meet the fuel supply needs of the micro-injection gas engine, and can restore the engine to full-power diesel engine state after the gas fuel is used up.

[0010] In order to solve the above-mentioned first technical problem, the technical solution adopted by the present invention is:

[0011] An electronically controlled single pump comprises: a pump body, a valve body fixedly mounted on the pump body and a push rod slidably mounted on the pump body, a main spring clamped between the valve body and the push rod, a roller extending out of the pump body mounted on the push rod, and the roller being controlled by an oil pumping cam of a camshaft; an oil inlet hole is formed on the pump body, an oil inlet passage, a main oil passage, a high-pressure chamber, an oil outlet hole and an oil return passage are formed on the valve body, the oil inlet hole is communicated with the oil inlet passage, one end of the main oil passage is communicated with the oil outlet hole, and the other end is communicated with the high-pressure chamber, and the oil return passage is formed on the valve body; A plunger is slidably installed in the valve body and abuts against the push rod. The oil pump cam drives the roller to drive the plunger to reciprocate, thereby pressurizing the fuel from the oil inlet hole to the high-pressure chamber. The valve body is provided with a first leakage channel connected to the main oil channel, and a first solenoid valve for controlling the on-off of the first leakage channel is installed on the valve body; the valve body is also provided with at least a second leakage channel connected to the main oil channel, and at least a second solenoid valve for controlling the on-off of the second leakage channel is installed on the valve body.

[0012] Among them, the first solenoid valve includes a first electromagnet, a first valve core and a first positioning seat, the first leakage channel includes a first valve core chamber, a first oil return chamber and an oil return channel which are opened on the valve body and connected in sequence, the first valve core chamber is communicated with the main oil channel, the first valve core is slidably arranged in the first valve core chamber and is sleeved with a first control spring, the first valve core is provided with a first valve core sealing surface, the valve body is provided with a first valve body sealing surface, and the end surface of the first valve core and the end surface of the first positioning seat have a distance between them for determining the opening lift of the first valve core, and under the action of the first electromagnet and the first control spring, the first valve core sealing surface is fitted or disengaged from the first valve body sealing surface to control the on-off of the first leakage channel.

[0013] Among them, the second solenoid valve includes a second electromagnet, a second valve core and a second positioning seat, the second leakage channel includes a second valve core chamber and a second oil return chamber which are opened on the valve body and communicate with each other, the second valve core chamber is communicated with the main oil channel, the second oil return chamber is communicated with the first oil return chamber through a connecting channel, the second valve core is slidably arranged in the second valve core chamber and is sleeved with a second control spring, the second valve core is provided with a second valve core sealing surface, the valve body is provided with a second valve body sealing surface, the end surface of the second valve core and the end surface of the second positioning seat have a distance for determining the opening lift of the second valve core, under the action of the second electromagnet and the second control spring, the second valve core sealing surface is fitted or disengaged from the second valve body sealing surface to control the on-off of the second leakage channel.

[0014] To solve the above second technical problem, the technical solution adopted by the present invention is:

[0015] A method for controlling oil supply using the above-mentioned electronically controlled unit pump, wherein the first solenoid valve and the second solenoid valve are normally open solenoid switch valves; under the control of the electronic control unit, when the engine needs to start boot injection, the first solenoid valve is closed and the second solenoid valve remains open; when the engine needs to start main injection, the second solenoid valve is closed, and when the engine needs to end the main injection, the first solenoid valve and the second solenoid valve are opened at the same time; when the engine needs to start post-injection, the first solenoid valve is closed, and when the engine needs to end injection, the first solenoid valve is opened, and during the post-injection process, the second solenoid valve remains open. Or

[0016] A method for controlling oil supply using the above-mentioned electronically controlled single pump, wherein the first solenoid valve and the second solenoid valve are respectively normally open solenoid switch valves; under the control of the electronic control unit, when the engine needs to start a micro-spray state, the first solenoid valve is closed, and when the engine needs to end the micro-spray state, the first solenoid valve is opened, and during this process, the second solenoid valve remains open.

[0017] After adopting the above technical solution, the technical effects achieved by the present invention are:

[0018] Since the valve body of the electronically controlled unit pump is provided with at least a first leakage channel and a second leakage channel connected to the main oil channel, the valve body is provided with at least a first solenoid valve for controlling the on-off of the first leakage channel and a second solenoid valve for controlling the on-off of the second leakage channel. When the first solenoid valve is closed, the first leakage channel is disconnected, and when the second solenoid valve is closed, the second leakage channel is disconnected. By controlling the opening and closing time of the first solenoid valve and the second solenoid valve, a variety of injection pressure waveforms can be formed. For example, the second solenoid valve is closed before or at the same time as the second solenoid valve through the electronic control unit, and the injection pressure waveform is the same as that of the conventional single solenoid valve unit pump (see Figure 6 ); For another example, the second solenoid valve is kept open through the electronic control unit, and the first solenoid valve is closed-opened. At this time, the injection pressure is mainly affected by the opening lift of the second solenoid valve core. Changing its size can adjust the injection pressure. The injection pressure in this case is significantly lower than that in the previous case (see Figure 7 ). By controlling the opening and closing time of the two solenoid valves, the three-stage fuel injection requirements of "pre-injection, main injection, and post-injection" of the engine in the diesel engine state can be achieved, and the fuel supply requirements of the micro-injection gas engine can be met. After the gas fuel is used up, the engine can be restored to the full-power diesel engine state. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a waveform diagram of the three stages of pre-injection, main injection and post-injection of the well-known diesel engine fuel supply system;

[0020] Figure 2 It is a waveform diagram of the three stages of shoe injection, main injection and post injection of the well-known diesel engine fuel supply system;

[0021] Figure 3 is a longitudinal sectional view of an embodiment of an electronically controlled monomer pump of the present invention;

[0022] Figure 4 yes Figure 3 A partial enlarged view of point Ⅰ in the middle;

[0023] Figure 5 yes Figure 3 A partial enlarged view of the middle II;

[0024] Figure 6 yes Figure 3 The fuel injection pressure waveform diagram of the embodiment shown when the second solenoid valve is closed before or simultaneously with the first solenoid valve;

[0025] Figure 7 yes Figure 3 The embodiment shown is a waveform diagram of the injection pressure as the first solenoid valve is closed-opened while the second solenoid valve remains open;

[0026] Figure 8 yes Figure 3 The embodiment shown implements the fuel injection pressure waveform diagram of the three stages of boot injection, main injection and post injection;

[0027] Fig. 9 yes Figure 3 A comparison diagram of the injection pressure waveform of the embodiment shown when implemented on a micro-injection dual-fuel gas engine and a unit injection pump of a conventional structure;

[0028] In the figure, 10, oil pump cam; 21, pump body; 211, oil inlet hole; 22, push rod; 23, roller; 24, main spring; 25, plunger; 26, valve body; 261, oil inlet channel; 262, high pressure chamber; 263, main oil channel; 264, first oil return chamber; 265, second oil return chamber; 266, oil return channel; 267, connecting channel; 268, first valve body sealing surface; 269, second valve body sealing surface; 31, first electromagnet; 32, first valve core; 321, first valve core sealing surface; 33, first control spring; 34, first positioning seat; 41, second electromagnet; 42, second valve core; 421, second valve core sealing surface; 43, second control spring; 44, second positioning seat; 50, high pressure oil pipe; 60, injector;

[0029] S1, the first valve core opening lift; S2, the second valve core opening lift;

[0030] t1, the time from closing to opening of the solenoid valve of the conventional structure single pump; tx, the time from closing to opening of the first solenoid valve of the embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] like Figure 3 As shown, an electrically controlled single pump, a pump body 21 is fixedly mounted with a valve body 26 and a push rod 22 is slidably mounted, a main spring 24 is clamped between the valve body 26 and the push rod 22, and the push rod 22 is mounted with a roller 23 extending out of the pump body 21, and the roller 23 is controlled by the oil pump cam 10 of the camshaft. For a large-cylinder engine, the camshaft is separate and is installed separately from the pump body 21; for a small-cylinder engine, the camshaft is integrated into the pump body 21 and is rotatably mounted with the pump body 21.

[0033] The pump body 21 is provided with an oil inlet hole 211, and the valve body 26 is provided with an oil inlet passage 261, a main oil passage 263, a high-pressure chamber 262, an oil outlet hole and an oil return passage 266. The oil inlet hole 211 is connected to the oil inlet passage 261, one end of the main oil passage 263 is connected to the oil outlet hole, and the other end is connected to the high-pressure chamber 262. The oil outlet hole is connected to a high-pressure oil pipe, and the high-pressure oil pipe 50 is connected to the injector 60. A plunger 25 is slidably mounted in the valve body 26 to abut against the push rod 22. The oil pump cam 10 drives the roller to drive the plunger to reciprocate, and the fuel from the oil inlet hole is pressurized to the high-pressure chamber 262, and is sprayed from the main oil passage 263 through the high-pressure oil pipe 50 by the injector 60.

[0034] The valve body 26 is provided with a first leakage channel and a second leakage channel respectively connected to the main oil channel 263, and a first solenoid valve for controlling the on and off of the first leakage channel and a second solenoid valve for controlling the on and off of the second leakage channel are respectively installed on the valve body 26. The opening lift of the valve core of the first solenoid valve is S1, and the opening lift of the valve core of the second solenoid valve is S2. It is set that S1>>S2, for example, it is designed that S1=0.15 mm, S2=0.015 mm, and this value can be adjusted as needed, and does not constitute a limitation on the protection scope of the present invention.

[0035] like Figure 3 and Figure 4As shown together, the first solenoid valve includes a first electromagnet 31, a first valve core 32 and a first positioning seat 34, the first leakage channel includes a first valve core chamber, a first oil return chamber 264 and an oil return channel 266 which are opened on the valve body 26 and are sequentially connected, the first valve core chamber is connected to the main oil channel 263, the first valve core 32 is slidably arranged in the first valve core chamber and is sleeved with a first control spring 33, the first valve core 32 is provided with a first valve core sealing surface 321, the valve body 26 is provided with a first valve body sealing surface 268, and there is a distance between the end surface of the first valve core 32 and the end surface of the first positioning seat 34 for determining the opening lift S1 of the first valve core. Under the action of the first electromagnet 31 and the first control spring 33, the first valve core sealing surface 321 is fitted or disengaged from the first valve body sealing surface 268 to control the on-off of the first leakage channel.

[0036] like Figure 3 and Figure 5 As shown together, the second solenoid valve includes a second electromagnet 41, a second valve core 42 and a second positioning seat 44, the second leakage channel includes a second valve core chamber and a second oil return chamber 265 which are opened on the valve body 26 and are connected to each other, the second valve core chamber is connected to the main oil channel 263, the second oil return chamber 265 is connected to the first oil return chamber 264 through a connecting channel 267, the second valve core 42 is slidably arranged in the second valve core chamber and is sleeved with a second control spring 43, the second valve core 42 is provided with a second valve core sealing surface 421, the valve body 26 is provided with a second valve body sealing surface 269, the end surface of the second valve core 42 and the end surface of the second positioning seat 44 have a distance for determining the opening lift S2 of the second valve core, under the action of the second electromagnet 41 and the second control spring 43, the second valve core sealing surface 421 is fitted or disengaged from the second valve body sealing surface 269 to control the on-off of the second leakage channel.

[0037] In this embodiment, the first oil return chamber 264 surrounds the outer circumference of the first positioning seat 34 , and the second oil return chamber 265 surrounds the outer circumference of the second positioning seat 44 .

[0038] In this embodiment, the first valve core sealing surface 321 and the first valve body sealing surface 268 are respectively matched sealing conical surfaces; the second valve core sealing surface 421 and the second valve body sealing surface 269 are respectively matched sealing conical surfaces.

[0039] In this embodiment, the first solenoid valve and the second solenoid valve are respectively normally open solenoid switch valves.

[0040] By controlling the opening and closing timings of the first solenoid valve and the second solenoid valve, a variety of injection pressure waveforms can be formed.

[0041] like Figure 6As shown, by controlling the second solenoid valve to close before or simultaneously with the first solenoid valve through the electronic control unit, the injection pressure waveform is the same as that of the conventional electronically controlled unit pump fuel supply system.

[0042] like Figure 7 As shown, the second solenoid valve is controlled by the electronic control unit to remain open, and the first solenoid valve is closed-opened. At this time, the injection pressure is mainly affected by the opening lift of the second solenoid valve core. By changing the size of S2, the injection pressure can be adjusted. In this case, the injection pressure is significantly lower than Figure 6 The situation shown.

[0043] like Figure 8 As shown in the figure, when the first solenoid valve is closed (the second solenoid valve remains open), a boot-shaped injection waveform is generated. Subsequently, the second solenoid valve is closed, and the main injection stage begins, and the pressure increases. After the first solenoid valve / the second solenoid valve are opened at the same time, the pressure begins to drop until the main injection ends. After a period of time, the first solenoid valve / the second solenoid valve can be controlled to achieve post-injection. Regarding the control of post-injection, it is quite necessary to keep the second solenoid valve open. Figure 8 The double-dotted line part is the post-injection waveform when the second solenoid valve is not set, and the solid line is the waveform of the second solenoid valve being opened. Figure 8 It can be seen that for the same amount of post-injection fuel, the solid line waveform corresponds to a longer duration. It can be seen that by setting the second solenoid valve, the requirements for the solenoid valve are reduced. The fuel supply control method can realize the three-stage fuel injection of "boot-shaped injection, main injection, and post-injection". Similarly, the effect of the three-stage fuel injection of "pre-injection, main injection, and post-injection" can also be expected.

[0044] like Fig. 9 As shown, in the micro-injection dual-fuel gas engine, the second solenoid valve is kept in a normally open state, and the time tx from the closing to the opening of the first solenoid valve is controlled, tx>>t1, so that a fuel injection amount with high precision and small injection amount can be obtained. It can be seen that the fuel supply control method can meet the fuel supply demand of the micro-injection gas engine, and can restore the engine to a full-power diesel engine state after the gas fuel is used up.

[0045] The present invention is not limited to the above-mentioned embodiments. For example, a combination of three or more solenoid valves may be used. By setting different valve core lifts, more injection waveforms may be generated. All improvements based on the concept, principle, structure and method of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An electronically controlled monomer pump, comprising: A pump body, wherein a valve body is fixedly mounted on the pump body and a push rod is slidably mounted on the pump body, a main spring is clamped between the valve body and the push rod, a roller extending out of the pump body is mounted on the push rod, and the roller is controlled by an oil pumping cam of a camshaft; an oil inlet hole is provided on the pump body, an oil inlet passage, a main oil passage, a high-pressure chamber, an oil outlet hole and an oil return passage are provided on the valve body, the oil inlet hole is communicated with the oil inlet passage, one end of the main oil passage is communicated with the oil outlet hole, and the other end is communicated with the high-pressure chamber, a plunger abutting against the push rod is slidably mounted on the valve body, the oil pumping cam drives the roller to drive the plunger to reciprocate, and the fuel from the oil inlet hole is pressurized to the high-pressure chamber; The valve body is provided with a first leakage channel connected with the main oil channel, and a first solenoid valve for controlling the on-off of the first leakage channel is installed on the valve body; the characteristics are as follows: The valve body is further provided with at least a second leakage channel communicating with the main oil channel, and the valve body is further provided with at least a second solenoid valve for controlling the on-off of the second leakage channel.

2. The electronically controlled unit pump according to claim 1, characterized in that: The first solenoid valve includes a first electromagnet, a first valve core and a first positioning seat, the first leakage channel includes a first valve core chamber, a first oil return chamber and an oil return channel which are opened on the valve body and are sequentially connected, the first valve core chamber is connected to the main oil channel, the first valve core is slidably arranged in the first valve core chamber and is sleeved with a first control spring, the first valve core is provided with a first valve core sealing surface, the valve body is provided with a first valve body sealing surface, and the end surface of the first valve core and the end surface of the first positioning seat have a distance between them for determining the opening lift of the first valve core, and under the action of the first electromagnet and the first control spring, the first valve core sealing surface is fitted or disengaged from the first valve body sealing surface to control the on-off of the first leakage channel.

3. The electronically controlled unit pump according to claim 2, characterized in that: The second solenoid valve includes a second electromagnet, a second valve core and a second positioning seat, the second leakage channel includes a second valve core chamber and a second oil return chamber which are opened on the valve body and are connected to each other, the second valve core chamber is connected to the main oil channel, the second oil return chamber is connected to the first oil return chamber through a connecting channel, the second valve core is slidably arranged in the second valve core chamber and is sleeved with a second control spring, the second valve core is provided with a second valve core sealing surface, the valve body is provided with a second valve body sealing surface, the end surface of the second valve core and the end surface of the second positioning seat have a distance for determining the opening lift of the second valve core, under the action of the second electromagnet and the second control spring, the second valve core sealing surface is fitted or disengaged from the second valve body sealing surface to control the on-off of the second leakage channel.

4. The electronically controlled unit pump according to claim 3, characterized in that: The first oil return chamber surrounds the outer circumference of the first positioning seat, and the second oil return chamber surrounds the outer circumference of the second positioning seat.

5. The electronically controlled unit pump according to claim 3, characterized in that: The first valve core sealing surface and the first valve body sealing surface are respectively matched sealing conical surfaces; the second valve core sealing surface and the second valve body sealing surface are respectively matched sealing conical surfaces.

6. The electronically controlled unit pump according to claim 1, characterized in that: The first solenoid valve and the second solenoid valve are respectively normally open solenoid switch valves.

7. The electronically controlled unit pump according to claim 1, characterized in that: The camshaft is rotatably mounted on the pump body, or the camshaft and the pump body are installed separately.

8. The electronically controlled unit pump according to claim 1, characterized in that: The oil outlet is connected to a high-pressure oil pipe, and the high-pressure oil pipe is connected to a fuel injector.

9. A method for controlling oil supply using the electronically controlled unit pump according to claim 3, characterized in that: The first solenoid valve and the second solenoid valve are normally open solenoid switch valves respectively; under the control of the electronic control unit, when the engine needs to start boot injection, the first solenoid valve is closed and the second solenoid valve remains open; when the engine needs to start main injection, the second solenoid valve is closed, and when the engine needs to end the main injection, the first solenoid valve and the second solenoid valve are opened at the same time; when the engine needs to start post-injection, the first solenoid valve is closed, and when the engine needs to end post-injection, the first solenoid valve is opened, and during the post-injection process, the second solenoid valve remains open.

10. A method for controlling oil supply using the electronically controlled unit pump according to claim 3, characterized in that: The first solenoid valve and the second solenoid valve are respectively normally open solenoid switch valves; under the control of the electronic control unit, when the engine needs to start the micro-spray state, the first solenoid valve is closed, and when the engine needs to end the micro-spray state, the first solenoid valve is opened. During this process, the second solenoid valve remains open.

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