Micro-jet ignition dual-fuel gas engine fuel supply system based on electronic unit pump

Abstract

The utility model discloses a micro-injection ignition dual-fuel gas engine fuel oil supply system based on an electronic control unit pump, which comprises the electronic control unit pump, an oil outlet hole of the electronic control unit pump is connected with a high-pressure oil pipe, and the high-pressure oil pipe is connected with an oil injector; the high-pressure oil pipe is connected with a drainage oil way communicated with the oil tank, and the drainage oil way comprises a switch electromagnetic valve and a pressure relief device which are arranged in series. On the basis of a common electronic unit pump, the drainage oil way is arranged on the high-pressure oil pipe, and when an engine works in a diesel engine state, the switch electromagnetic valve is closed; when the engine works in a micro-jet state, the switch electromagnetic valve is communicated with the oil way, most of fuel oil in the high-pressure oil way is discharged under the action of the pressure relief device, the jet quantity of the oil sprayer is greatly reduced, the cam rotating angle corresponding to the oil pumping cam is increased, the requirement for the single pump electromagnetic valve is obviously reduced, and therefore the requirement of the micro-jet engine is met.

Description

Technical Field

[0001] The utility model relates to the technical field of engine fuel supply systems, in particular to a fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump. Background Art

[0002] For a micro-injection ignition dual-fuel gas engine, the fuel supply system is divided into a fuel supply system and a gas supply system. It means that a small amount of diesel (1% - 5% of the full-load fuel quantity) is used as the ignition fuel and is injected into the cylinder for compression ignition to ignite the main gas fuel for work. Compared with a spark-ignition gas engine, the micro-diesel ignition system has a large ignition energy and good penetration, which can significantly improve the power performance and economy of the engine; when the gas fuel is used up, the engine can burn diesel fuel alone and become a diesel engine for output work.

[0003] When the engine is operating in the state of a micro-injection ignition gas engine, since the fuel is the ignition energy of the gas fuel, the amount of fuel injection per cycle determines the size of the ignition energy, directly determines the combustion characteristics of the gas fuel, and thus affects the performance of the engine. Therefore, the control precision requirement for the supply of a small amount of injected fuel is very high. The commonly used fuel supply system is a high-pressure common rail fuel supply system. The fuel pressure in the rail pipe is stable, and the fuel injection quantity is controlled by the opening time of the solenoid valve. The control precision is high and can meet the fuel supply requirements of micro-injection ignition.

[0004] The high-pressure common rail fuel supply system has been widely used in diesel engines with a power of less than 500KW. For large engines with a power greater than 1000KW, the matching high-pressure common rail fuel supply system has a substantial increase in cost due to process and structural changes, and the price increases by more than ten times, which limits its application. Therefore, most large diesel engines still use an electronically controlled unit pump fuel supply system.

[0005] The traditional electronically controlled unit pump fuel supply system usually includes a cam, a fuel pumping system, a solenoid valve, a high-pressure fuel pipe, and an injector. The cam drives the roller to drive the plunger to reciprocate, boosting the diesel to the high-pressure chamber. When the electromagnet is not energized, the sealing conical surface does not fit, and the diesel in the high-pressure chamber leaks through the gap of the sealing conical surface. The diesel in the high-pressure fuel pipe does not build up high pressure and cannot drive the injector to open, and the injector does not inject fuel; when the solenoid valve is energized, the sealing conical surface fits, the diesel pressure in the high-pressure chamber increases, enters the injector through the high-pressure fuel pipe, and after the diesel pressure reaches the opening pressure of the injector, the injector opens to inject diesel into the cylinder. When the solenoid valve is de-energized again, the sealing conical surface is opened to relieve pressure under the action of the spring force, and the injector stops injecting fuel.

[0006] During the cam pump oil process, by controlling the duration from the closing to the opening moment of the solenoid valve, the fuel supply volume per cycle of the unit pump can be controlled. Under certain rotational speed conditions, the duration from the closing to the opening moment of the solenoid valve corresponds to the cam angle. If this system meets the requirements of a micro-injection engine and the fuel injection volume needs to reach 1% - 5% of the full-load fuel volume, then the corresponding cam angle during micro-injection operation must be quite small. For example, if the duration from the closing to the opening moment of the solenoid valve corresponding to a certain engine rotational speed is 2 milliseconds, then the corresponding time requirement during micro-injection is less than 0.2 milliseconds, which far exceeds the response time requirement of the solenoid valve.

[0007] For the micro-injection engines of some manufacturers, the adopted solution is: matching a small high-pressure common rail fuel system. For example, for a 1000KW engine, the matched high-pressure common rail system can only meet the diesel supply demand of 300KW. This solution solves the problems of the control accuracy and cost of the fuel supply system (the cost of the small high-pressure common rail system is low), but when the gaseous fuel is used up, it cannot return to the full-power diesel engine state operation (it can only return to the 300KW diesel engine state), which limits its application. Summary of the Utility Model

[0008] In view of this, the present utility model provides a fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump to meet the fuel supply demand of the micro-injection ignition dual-fuel gas engine.

[0009] To solve the above technical problems, the technical solution adopted by the present utility model is:

[0010] A fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump, comprising:

[0011] A diesel engine cam, the diesel engine cam is installed on a camshaft; an electronically controlled unit pump, the electronically controlled unit pump includes a pump body, a valve body and a push rod, the valve body is fixedly installed in the pump body, the push rod is slidably installed in the pump body, a main spring is clamped between the valve body and the push rod, and a roller extending out of the pump body is installed on the push rod; an oil inlet hole is opened 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 opened 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 abutted against the push rod is slidably installed in the valve body, the diesel engine cam drives the roller to drive the plunger to reciprocate, and pressurizes the fuel from the oil inlet hole to the high-pressure chamber; a bleed passage communicated with the main oil passage is opened on the valve body, and a unit pump solenoid valve for controlling the on-off of the bleed passage is installed on the valve body; the oil outlet hole is connected to a high-pressure oil pipe, and the high-pressure oil pipe is connected to an injector; a bleed oil circuit communicated with a fuel tank is connected to the high-pressure oil pipe, and the bleed oil circuit includes a switch solenoid valve and a pressure relief device arranged in series.

[0012] Wherein, the pressure relief device includes a relief valve.

[0013] Wherein, the pressure relief device includes a relief valve and a throttling structure arranged in series.

[0014] Wherein, the unit pump solenoid valve includes an electromagnet, a valve core and a positioning seat. The drain passage includes a valve core cavity, an oil return cavity and an oil return passage which are sequentially communicated and opened on the valve body. The valve core cavity communicates with the main oil passage. The valve core is slidably arranged in the valve core cavity and sleeved with a control spring. The valve core is provided with a valve core sealing surface, and the valve body is provided with a valve body sealing surface. There is a distance between the end surface of the valve core and the end surface of the positioning seat to determine the opening lift of the valve core. Under the action of the electromagnet and the control spring, the valve core sealing surface fits or disengages from the valve body sealing surface to control the on-off of the drain passage.

[0015] Wherein, the oil return cavity surrounds the outer peripheral surface of the positioning seat.

[0016] Wherein, the valve core sealing surface and the valve body sealing surface are respectively mating sealing conical surfaces.

[0017] Wherein, the unit pump solenoid valve is a normally open electromagnetic switch valve.

[0018] After adopting the above technical solutions, the technical effects achieved by the present utility model are:

[0019] On the basis of a common electronically controlled unit pump, the present utility model provides a drain oil circuit on the high-pressure oil pipe. The drain oil circuit includes a switch solenoid valve and a pressure relief device arranged in series. When the engine operates in the diesel state, the switch solenoid valve is closed; when the engine operates in the micro-injection state, the switch solenoid valve connects the oil circuit. Under the action of the pressure relief device, most of the fuel in the high-pressure oil circuit is drained, greatly reducing the injection volume of the injector. The cam angle corresponding to the pump oil cam will increase, and the requirements for the unit pump solenoid valve are significantly reduced, thus meeting the requirements of the micro-injection engine.

[0020] In the present utility model, the pressure relief device can be a relief valve or a relief valve and a throttling structure arranged in series. By adjusting the elastic force of the pressure regulating spring of the relief valve, the pressure and the drain flow rate of the oil circuit are adjusted. The throttling structure mainly controls the flow rate, and the relief valve mainly controls the pressure. The combination of the two can improve the control accuracy. Description of the Drawings

[0021] Figure 1 is a longitudinal sectional view of an embodiment of a fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump of the present utility model;

[0022] Figure 2 isFigure 1 Partial enlarged view at position Ⅰ;

[0023] Figure 3 is Figure 1 the specific structure of the pressure relief device in

[0024] Figure 4 is Figure 1 another specific structure of the pressure relief device of

[0025] In the figure, 10 is the diesel engine cam; 20 is the electronic control unit pump; 21 is the pump body; 211 is the oil inlet hole; 22 is the push rod; 23 is the roller; 24 is the main spring; 25 is the plunger; 26 is the valve body; 261 is the oil inlet passage; 262 is the high-pressure chamber; 263 is the main oil passage; 264 is the oil return chamber; 266 is the oil return passage; 268 is the valve body sealing surface; 27 is the unit pump solenoid valve; 271 is the electromagnet; 272 is the valve core; 273 is the control spring; 274 is the positioning seat; 275 is the valve core sealing surface; 41 is the switch solenoid valve; 42 is the pressure relief device; 42A is the overflow valve; 42B is the throttling structure; 42C is the fuel tank; 50 is the high-pressure oil pipe; 60 is the injector; S1 is the valve core opening lift. Specific embodiments

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] Figure 1 shows the structure of a micro-injection ignition dual-fuel gas engine fuel supply system based on an electronic control unit pump in the diesel engine state, as shown in Figure 1 and Figure 2 shown, the electronic control unit pump 20 includes a pump body 21, a valve body 26, a push rod 22 and a unit pump solenoid valve 27, etc. The pump body 21 is fixedly installed with the valve body 26 and slidably installed with the push rod 22. A main spring 24 is clamped between the valve body 26 and the push rod 22. The push rod 22 is installed with a roller 23 extending out of the pump body 21, and the roller 23 is controlled by the diesel engine cam 10 installed on the camshaft.

[0028] 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 communicated with the oil inlet passage 261. One end of the main oil passage 263 is communicated with the oil outlet hole and the other end is communicated with the high-pressure chamber 262. The oil outlet hole is connected to the high-pressure oil pipe, and the high-pressure oil pipe 50 is connected to the injector 60. A plunger 25 that abuts against the push rod 22 is slidably installed in the valve body 26. The diesel engine cam 10 drives the roller to drive the plunger to reciprocate, pressurizing the fuel from the oil inlet hole to the high-pressure chamber 262, and spraying it out from the main oil passage 263 through the high-pressure oil pipe 50 by the injector 60.

[0029] The valve body 26 is provided with a drain passage communicating with the main oil passage 263, and a unit pump solenoid valve 27 for controlling the on / off of the drain passage is also installed on the valve body 26. The opening lift of the solenoid valve spool is S1.

[0030] The unit pump solenoid valve 27 includes an electromagnet 271, a spool 272 and a positioning seat 274. The drain passage includes a spool cavity, an oil return cavity 264 and an oil return passage 266 which are sequentially communicated and opened on the valve body 26. The spool cavity communicates with the main oil passage 263. The spool 272 is slidably arranged in the spool cavity and sleeved with a control spring 273. The spool 272 is provided with a spool sealing surface 275, and the valve body 26 is provided with a valve body sealing surface 268. There is a distance between the end face of the spool 272 and the end face of the positioning seat 274 to determine the opening lift S1 of the spool. Under the action of the electromagnet 271 and the control spring 273, the spool sealing surface 275 is in contact or separated from the valve body sealing surface 268 to control the on / off of the drain passage.

[0031] The main contribution of the present utility model to the prior art is that a drain oil circuit communicating with the fuel tank 42C is connected to the high-pressure oil pipe 50. The drain oil circuit includes a switch solenoid valve 41 and a pressure relief device 42 arranged in series. When the engine operates in the diesel state, the switch solenoid valve 41 is closed; when the engine operates in the micro-injection state, the switch solenoid valve 41 connects the drain oil circuit. Under the action of the pressure relief device, most of the fuel in the high-pressure oil circuit is drained, so that the injection amount of the injector is greatly reduced, and the cam angle corresponding to the pump oil cam will increase, and the requirements for the unit pump solenoid valve are significantly reduced, thus meeting the requirements of the micro-injection engine.

[0032] As Figure 3 shown, the pressure relief device 40 is an overflow valve 42A, and the pressure and drain flow of the oil circuit are adjusted by adjusting the elastic force of the overflow valve pressure regulating spring.

[0033] As Figure 4 shown, the pressure relief device 40 is an overflow valve 42A and a throttling structure 42B arranged in series. The throttling structure 42B mainly controls the flow, and the overflow valve 42A mainly controls the pressure. The combination of the two can improve the control accuracy.

[0034] In this embodiment, the oil return cavity 264 surrounds the outer peripheral surface of the positioning seat 274.

[0035] In this embodiment, the spool sealing surface 275 and the valve body sealing surface 268 are respectively mating sealing conical surfaces.

[0036] In this embodiment, the unit pump solenoid valve 27 is a normally open electromagnetic switch valve.

[0037] The present utility model is not limited to the above embodiments, and all kinds of improvements made based on the concept, principle, structure and method of the present utility model will fall within the protection scope of the present utility model.

Claims

1. A fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump, comprising: A diesel engine cam, wherein the diesel engine cam is mounted on a camshaft; An electronically controlled single-unit pump, the electronically controlled single-unit pump comprising a pump body, a valve body and a push rod, the valve body being fixedly mounted in the pump body, the push rod being slidably mounted in the pump body, a main spring being clamped between the valve body and the push rod, and a roller extending out of the pump body being mounted on the push rod; an oil inlet hole is provided in 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 in 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 in the valve body, the diesel engine 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; a leakage passage connected to the main oil passage is provided in the valve body, and a single-unit pump solenoid valve for controlling the on-off of the leakage passage is mounted on the valve body; The oil outlet is connected to a high-pressure oil pipe, and the high-pressure oil pipe is connected to a fuel injector; the characteristic is that: The high-pressure oil pipe is connected to a leakage oil circuit communicated with the oil tank, and the leakage oil circuit includes a switch solenoid valve and a pressure relief device arranged in series.

2. The micro-injection ignition dual-fuel gas engine fuel supply system based on an electronically controlled unit pump as claimed in claim 1, characterized in that: The pressure relief device comprises a relief valve.

3. The fuel supply system for a dual-fuel gas engine based on a micro-injection ignition pump and an electronically controlled unit pump as claimed in claim 1, characterized in that: The pressure relief device comprises a relief valve and a throttling structure which are arranged in series.

4. The fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump as claimed in claim 1, characterized in that: The monomer pump solenoid valve includes an electromagnet, a valve core and a positioning seat, the leakage passage includes a valve core chamber, an oil return chamber and an oil return passage which are opened on the valve body and connected in sequence, the valve core chamber is connected to the main oil passage, the valve core is slidably arranged in the valve core chamber and is sleeved with a control spring, the valve core is provided with a valve core sealing surface, the valve body is provided with a valve body sealing surface, and the end surface of the valve core and the end surface of the positioning seat have a distance between them for determining the opening lift of the valve core. Under the action of the electromagnet and the control spring, the valve core sealing surface and the valve body sealing surface are fitted or disengaged to control the on-off of the leakage passage.

5. The fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump as claimed in claim 4, characterized in that: The oil return chamber surrounds the outer peripheral surface of the positioning seat.

6. The fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump as claimed in claim 4, characterized in that: The valve core sealing surface and the valve body sealing surface are respectively matched sealing conical surfaces.

7. The fuel supply system for a micro-injection ignition dual-fuel gas engine based on an electronically controlled unit pump as claimed in claim 1, characterized in that: The monomer pump solenoid valve is a normally open solenoid switch valve.

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