CN2911225Y - Flexible regulatable superhigh pressure fuel jetting unit - Google Patents

Abstract

The utility model discloses a flexible adjustable ultra-high pressure fuel injection device for a diesel engine, which can make the fuel injection pressure of an automobile engine reach an ultrahigh pressure. The device includes a pressure closed-loop feedback control circuit composed of a low-pressure oil pump, an electronically controlled medium-pressure plunger pump, a pressure accumulator, a relief valve, a pressure sensor and an electronic control unit, and a first one-way valve, a first two-position two-way An ultra-high pressure fuel injection circuit composed of a solenoid valve, a supercharger and an injector; the electronically controlled medium-pressure plunger pump in the pressure closed-loop feedback control circuit is connected to the plunger by a plunger pair and an oil circuit respectively. The second two-position two-way solenoid valve and the second one-way valve in the plunger chamber of the paired part are formed, and the plunger in the plunger paired part is connected to the cam driving mechanism through a roller. The utility model has the advantages of simple structure, convenient adjustment, good pressure stability, super high pressure fuel injection pressure can be realized on the basis of medium pressure, and the industrialization of technology can be easily realized.

Description

Flexible adjustable ultra-high pressure fuel injection device for diesel engine

technical field

The utility model relates to an automobile engine, in particular to an ultra-high pressure fuel injection device for a diesel engine.

technical background

At present, electronically controlled high-voltage common rail technology has become one of the advanced electronically controlled technologies for diesel engines. The technical solution consists of an electronically controlled high-pressure plunger pump, a common rail pipe, an electronically controlled fuel injector, a communicating pump, and a high-pressure oil pipe connecting the common rail pipe and the injector. The generation and adjustment process of the high pressure of the common rail pipe is to dynamically adjust the effective oil pressure stroke of the plunger by electronically controlling the closing time of the pressure control valve (PCV valve) at the oil inlet of the high pressure plunger pump, so as to control the pressure of the high pressure pump. The oil supply of the common rail pipe is realized. The common rail pipe is equipped with a pressure sensor, which can feed back the rail pressure to the electronic control unit (ECU) during the process of adjusting the common rail pressure, and the electronic control unit (ECU) sends a pressure control valve through logic analysis. (PCV valve) control command to realize closed-loop feedback control of common rail pressure.

From the perspective of the working process of the diesel engine itself, high fuel injection pressure can not only shorten the penetration distance of the injected fuel beam in the cylinder, effectively reduce the amount of fuel hitting the wall caused by too long penetration distance, but also accelerate the breakage of the liquid injected fuel beam Evaporate and promote the mixing of fuel and air. Therefore, the improvement of these factors can greatly optimize the combustion process of the diesel engine, greatly reduce the _NOx and soot emissions of the diesel engine, and improve its economy.

The above-mentioned advantages of high fuel injection pressure have prompted the international high-pressure common rail technology to develop towards an ultra-high pressure injection pressure greater than 2000bar. At present, the injection pressure of foreign high-pressure common rail systems can reach 1600bar, and very few can reach 1850bar, but it is very difficult to achieve an ultra-high pressure exceeding 2000bar. The reasons are: First, the structure of the high-pressure common rail system determines that its common rail pipes, fuel injectors and high-pressure oil pipes have been working in a high-pressure environment, which requires these components to have good material mechanical properties and high The processing accuracy, especially the connection parts of these parts, if there is a slight defect in the working process, it will cause leakage. Therefore, the equipment for processing these parts must also have very high processing accuracy; To make the common rail pressure reach an ultra-high pressure of more than 2000bar, higher requirements are put forward for the oil pumping capacity of the high pressure plunger pump. If the oil outlet check valve in the high-pressure plunger pump is to be opened, it can only be realized when the pressure in the plunger cavity of the high-pressure plunger pump is greater than the opening pressure of the check valve, and only when the check valve is opened, the said Only the high-pressure plunger pump can supply oil to the common rail pipe, that is to say, when the pressure of the common rail pipe is 2000bar, the pressure of the plunger chamber of the high-pressure plunger pump is higher than 2000bar. Higher requirements are put forward for the machining accuracy and material mechanical properties of the mating parts. However, due to the limitations of domestic processing equipment and materials used for plungers and plunger sleeves, even if a mature ultra-high pressure common rail technology is developed, it is difficult to industrialize the technology.

Utility model content

The problem to be solved by the utility model is to provide an ultra-high pressure that can easily make the fuel injection pressure of the fuel supply system reach more than 2000 bar in order to promote the application of the electronically controlled high-pressure common rail technology, and it is not harmful to the parts materials and processing equipment. A flexible and adjustable ultra-high pressure diesel engine fuel injection device without high requirements.

The flexible adjustable ultra-high pressure diesel engine fuel injection device of the utility model includes a pressure closed-loop feedback control circuit composed of a low-pressure oil pump, an electronically controlled medium-pressure plunger pump, a pressure accumulator, an overflow valve, a pressure sensor and an electric control unit. An ultra-high pressure fuel injection circuit composed of a first check valve, a first two-position two-way solenoid valve, a supercharger and an injector; the electronically controlled medium-pressure plunger pump in the pressure closed-loop feedback control circuit is controlled by a column The plunger couple and the second two-position two-way solenoid valve and the second one-way valve respectively connected to the plunger cavity of the plunger couple through the oil circuit, the plunger in the plunger couple is driven by a roller connected with a cam mechanism, the oil outlet of the low-pressure oil pump is connected to the oil inlet of the second two-position two-way solenoid valve, and the oil inlet of the accumulator is connected to the oil outlet of the second one-way solenoid valve, so The pressure accumulator is provided with a pressure sensor and an overflow valve, and the pressure sensor is connected to the electronic control unit; the supercharger in the ultra-high pressure fuel injection circuit is provided with a piston chamber and a piston The large chamber, the small piston chamber is connected to the accumulator through the medium pressure oil pipe, and realizes the output of the ultra-high pressure injection pressure through the ultra-high pressure oil pipe, and the large piston chamber is connected to the pressure accumulator through the first two-position two-way electromagnetic The valves are respectively connected to the oil outlet of the pressure accumulator and the oil tank.

The electric-controlled medium-pressure plunger pump is provided with 1 to 6 plunger couples;

The arrangement of the plunger pair is in-line or star;

The camshaft of the cam driving mechanism is provided with 1 to 6 cams, and each cam is provided with 1 to 3 peaches;

The low-pressure oil pump is any one of a gear pump, a plunger pump, a rotor pump and a vane pump;

The beneficial effects of the utility model are: simple structure, convenient adjustment and control, flexible and adjustable output pressure, good pressure stability of the pressure accumulator, ultra-high pressure fuel injection pressure can be realized on the basis of medium pressure, and the machining accuracy of the plunger pair And the performance of the material is not too high, and it is easy to realize the industrialization of the technology.

Description of drawings

Accompanying drawing is the system schematic diagram of the utility model.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described in detail.

The accompanying drawing shows the principle diagram of the ultra-high pressure fuel injection device for diesel engines that can be flexibly adjusted in the present invention. It can be seen from the figure that the system includes a pressure closed-loop feedback control circuit 5 composed of a low-pressure oil pump 16, an electronically controlled medium-pressure plunger pump 15, an electronic control unit 4, a pressure accumulator 9, a relief valve 8 and a pressure sensor 10, and a pressure closed-loop feedback control circuit 5 composed of a first An ultra-high pressure fuel injection circuit 17 composed of a check valve 3, the first two-position two-way solenoid valve 6, a supercharger 7, an ultra-high pressure oil pipe 2 and a fuel injector 1; The medium-pressure control plunger pump 15 is composed of a plunger coupling 11 and a second two-position two-way electromagnetic valve 14 and a second check valve 12 respectively connected to the plunger cavity of the plunger coupling 11 through an oil circuit. The plunger of the plunger pair 11 is connected to the cam driving mechanism 13 through a roller, and is driven by the cam driving mechanism 13. The oil outlet of the low-pressure oil pump 16 is connected to the port of the second two-position two-way solenoid valve 14. oil inlet, the oil inlet of the pressure accumulator 9 is connected to the oil outlet of the second check valve 12, and the oil outlet of the pressure accumulator 9 is respectively connected to the first two-position two-way solenoid valve 6 and the first one-way valve 3, the pressure accumulator 9 is provided with a pressure sensor 10 and a relief valve 8, the pressure sensor 10 is connected to the electronic control unit 4; In the ultra-high pressure fuel injection circuit 17, the first two-position two-way solenoid valve 6 and the first one-way valve 3 are respectively connected to the large piston chamber and the small piston chamber of the supercharger 7, and the supercharger 7 The piston chamber is connected to the first one-way valve 3 through the medium pressure oil pipe, and realizes the output of the ultrahigh pressure fuel injection pressure through the ultrahigh pressure oil pipe 2, and the pressure amplification of the supercharger is realized through the displacement of its piston.

The electronically controlled medium-pressure plunger pump 14 can be provided with 1 to 6 plunger couples 11 as required, and there are two arrangements of the plunger couples 11: one is a plurality of plunger couples 11 arranged vertically The straight direction is arranged side by side above the camshaft of the convex theory driving mechanism 13 in-line type, and one is that a plurality of plunger couples 11 are distributed in a plane with the camshaft as the center and distributed in an equiangular manner. type.

The number of cams provided on the camshaft of the cam drive mechanism 13 and the number of peaches on each cam are based on the actual required range of fuel ultra-high pressure injection pressure and the number of ultra-high pressure injections. The general principle is to set 1 to 6 cams on the camshaft, and arrange 1 to 3 cams on each cam. The total number of cams should be set equal to the number of ultra-high pressure injections, and the distribution phase of each cam should be reasonable. distribute. For example, for a diesel engine requiring 4 ultra-high pressure injections, 2 cams can be arranged on the camshaft of the cam drive mechanism 13, and 2 lobe can be arranged on each cam, and the phase angle occupied by each lobe is 180 degrees. This arrangement allows the electric control medium pressure plunger pump 15 corresponding to each peach to supply oil to the accumulator 9 through the second check valve 12 and the accumulator 9 through the first check valve. 2. The process of supplying oil to the piston chamber is corresponding, so that the amount of fuel in the pressure accumulator 9 can be balanced in and out during the working process, thereby achieving the purpose of effectively reducing the pressure fluctuation of the pressure accumulator 9 .

For the convenience of system setting, the low-pressure oil pump 16 can be gear pump, plunger pump, rotor pump or vane pump. In order to meet different requirements, the fuel injector 1 can also be electronically controlled or mechanical.

When the device is not working, the second two-position two-way solenoid valve 14 in the pressure closed-loop feedback control circuit 5 and the plunger cavity of the plunger coupler 11 maintain the oil circuit normally open state, and the plunger is in the cam mechanism 13 to reciprocate; when the plunger goes down, the fuel delivered by the low-pressure oil pump 16 is sucked into the plunger chamber of the plunger pair 11, and when the plunger goes up, the sucked fuel passes through the second one-way electromagnetic The valve 14 is pressed back to the low-pressure oil circuit. At this time, the first two-position two-way solenoid valve 6 in the ultra-high pressure fuel injection circuit 17 opens the oil circuit leading to the fuel tank, and at the same time closes the oil circuit leading to the supercharger 7 piston. The oil circuit in the big room.

When the device is working, when the plunger in the plunger pair 11 is at a certain moment during the upward movement, the second two-position two-way solenoid valve 14 will lead to The oil path of the plunger chamber of the plunger coupler 11 is closed, and the oil path leading to the oil tank is opened, and the plunger starts to press oil, so that the pressure in the plunger chamber rises rapidly. When the pressure exceeds the opening pressure of the second one-way valve 12, the second one-way valve 12 is opened to allow the medium-pressure oil in the plunger chamber to enter the pressure accumulator 9, and then the The pressure sensor 10 on the top transmits the change of the pressure to the electronic control unit 4, so as to control and adjust the amount of fuel entering the pressure accumulator 9. When the pressure of the pressure accumulator 9 exceeds its rated working pressure, the overflow valve 8 will automatically open to send the fuel in the pressure accumulator 9 back to the fuel tank to protect the pressure accumulator 9 . After the pressure in the pressure accumulator 9 is adjusted to the required boost pressure value, the first two-position two-way solenoid valve 6 is controlled by the electronic control unit 4 to cut off the oil circuit leading to the fuel tank, and Connect the oil circuit leading to the large piston chamber of the supercharger 7, so that the medium-pressure oil enters the large piston chamber and pushes the piston in the supercharger 7 to move upward, and compresses the medium-pressure fuel oil filled with the small piston chamber (the pressure value is equal to the accumulated pressure The pressure value in the device 9), so that after being boosted by the supercharger 7, the ultra-high pressure fuel injection pressure is output through the ultra-high pressure oil pipe 2, and the injection is completed through the fuel injector 1. The pressure value of the pressure output is equal to the The product of the pressure value of the pressure accumulator 9 and the boost ratio of the supercharger 7. Therefore, if the pressure of the accumulator 9 is adjusted to a medium pressure value of 500-600 bar, the fuel injection pressure can be easily adjusted only by setting the boost ratio of the supercharger 7 to 3.4-4. Increased to ultra-high pressure above 2000bar.

When the ultra-high pressure injection is finished, the first two-position two-way solenoid valve 6 reopens the oil circuit from the large piston chamber of the supercharger 7 to the fuel tank under the control of the electronic control unit 4, and cuts off the connection with the oil tank. Describe the oil circuit of the pressure accumulator 9. The medium-pressure oil in the piston large chamber can flow back to the oil tank rapidly like this, and the pressure in the piston large chamber also drops rapidly correspondingly simultaneously, and the pressure in the piston small chamber drops with the piston in the supercharger 7 moving down, and then The first one-way valve 3 is opened under the action of the pressure oil in the pressure accumulator 9, so that the pressure accumulator 9 supplies oil to the piston chamber of the supercharger 7 through the first one-way valve 3, and at the same time Its piston is pressed to bottom dead center, gets ready for the ultra-high pressure fuel output work of supercharger 7 next time.

The flexible adjustable ultra-high pressure diesel engine fuel injection device of the present utility model can flexibly control the closing advance time of the second two-position two-way solenoid valve 14 in the electric control plunger pump 15 through the electronic control unit 4 in due course. The oil quantity provided by the medium-pressure plunger pump 15 to the pressure accumulator 9 is electronically controlled, so as to flexibly adjust the pressure to be boosted of the pressure accumulator 9 . It should be pointed out that: the closing advance time of the second two-position two-way solenoid valve 14 is determined by the target pressure value and the actual pressure value of the pressure accumulator 9 that needs to be boosted, and its range is within the range of the plunger pair 11 The plunger is within the range of rotation angles of the camshaft in the cam drive mechanism 13 from the bottom dead center to the top dead center. Since the ultra-high pressure output pressure of the system is obtained by the pressure of the pressure accumulator 9 through the amplification of the supercharger 7, the ultra-high pressure working pressure of the system can be flexibly adjusted. In addition, by adjusting the The number of driving cams in the plunger pump 15 and the distribution phases of the number of peaches on the cam can also adjust the pressure stability of the pressure accumulator 9 .

The utility model overcomes the deficiencies of the prior art, and provides a technical scheme different from the prior art in order to realize an ultra-high pressure exceeding 2000 bar and solve the problem that the material performance and machining accuracy of parts are difficult to meet the ultra-high pressure requirements , compared with the prior art, has substantive characteristics and progress, and is conducive to the popularization and application of electronically controlled high-voltage common rail technology.

Claims (5)

1. A flexible and adjustable ultra-high pressure fuel injection device for diesel engines, comprising a pressure closed-loop feedback control loop and an ultra-high pressure fuel injection loop, characterized in that the pressure closed-loop feedback control loop consists of a low-pressure oil pump and an electronically controlled medium-pressure plunger pump, accumulator, overflow valve, pressure sensor and electronic control unit, and the ultra-high pressure fuel injection circuit is composed of the first one-way valve, the first two-position two-way solenoid valve, supercharger and fuel injector The electronically controlled medium-pressure plunger pump in the pressure closed-loop feedback control circuit is composed of a plunger coupler and a second two-position two-way solenoid valve and a second two-way solenoid valve connected to the plunger chamber of the plunger coupler through an oil circuit. Two one-way valves, the plunger in the plunger pair is connected to the cam drive mechanism through the roller, the oil outlet of the low-pressure oil pump is connected to the oil inlet of the second two-position two-way solenoid valve, and the accumulator The oil inlet of the pressure accumulator is connected to the oil outlet of the second one-way solenoid valve, the pressure accumulator is provided with a pressure sensor and a relief valve, and the pressure sensor is connected to the electronic control unit; The supercharger in the ultra-high pressure fuel injection circuit is provided with a small piston chamber and a large piston chamber that are not connected to each other. The small piston chamber is connected to the pressure accumulator through a medium-pressure oil pipe, and the ultra-high pressure injection is realized through the ultra-high pressure oil pipe. For pressure output, the large piston chamber is respectively connected to the oil outlet of the pressure accumulator and the oil tank through the first two-position two-way solenoid valve. 2. The flexible adjustable ultra-high pressure fuel injection device for diesel engines according to claim 1, characterized in that the electronically controlled medium-pressure plunger pump is provided with 1 to 6 plunger couples. 3. The flexible adjustable ultra-high pressure fuel injection device for diesel engine according to claim 1, characterized in that the arrangement of the plunger couples is in-line or star. 4. The flexible adjustable diesel engine ultra-high pressure fuel injection device according to claim 1, characterized in that 1 to 6 cams are arranged on the camshaft of the cam drive mechanism, and each cam is provided with 1 to 6 cams. 3 peaches. 5. The flexible and adjustable ultra-high pressure fuel injection device for diesel engines according to claim 1, wherein the low-pressure oil pump is any one of a gear pump, a plunger pump, a rotor pump and a vane pump.