CN104018964B - Pressure accumulator current limiting piezoelectric control injector - Google Patents

Abstract

The invention aims to provide a pressure accumulation flow-limiting type piezoelectric control oil injector which comprises an oil injector head, an oil injector body, a flow limiting assembly, a piezoelectric control assembly, a needle valve reset spring, a positioning pin, a nozzle, a needle valve limiting block, a valve seat, a tightening cap and a sealing ring. By adopting the structure of the current-limiting assembly, the fuel economy reduction caused by abnormal continuous oil injection of the oil injector can be effectively avoided, and the working reliability of the oil injector is ensured; when the common rail fuel system is used, the structural size of the common rail pipe can be reduced, so that the strength requirement of the common rail pipe material is reduced, and the service life and the space utilization rate of the common rail pipe material can be improved; the action process of the needle valve is directly driven by the piezoelectric stack, the needle valve is high in response speed and control precision, the oil injection rule is flexible and changeable, and the dynamic property and the economical efficiency of the diesel engine are effectively improved.

Description

Pressure accumulator current limiting piezoelectric control injector

technical field

The invention relates to a fuel injector, specifically a diesel fuel injector.

Background technique

Traditional mechanically controlled fuel injectors have the main advantages of simple structure and high operational reliability, but because the fuel injection timing, fuel injection pressure and fuel injection rate are restricted by the shape of the high-pressure fuel pump cam, it has slow fuel injection response and poor control of fuel injection. It is difficult to improve the fuel economy and emission characteristics of the engine on the basis of poor measurement accuracy and other deficiencies. Compared with the mechanically controlled injector, the electromagnetically controlled injector used in the diesel engine electronic injection system has faster response speed, flexible and controllable fuel injection characteristics, and more accurate control of the fuel injection quantity. However, it also has the following Disadvantages: The control piston above the needle valve plays a certain role in further improving the response speed of the fuel injector; the fuel injector will cause the turbulent flow to intensify during the working process of fuel injection and fuel cut-off, which will cause severe damage to the fuel system. Pressure fluctuations lead to large fluctuations in fuel injection pressure and fuel injection rate, making it difficult to control the fuel injection volume; the structure of the electromagnetic control injector is complex, and the inductance of the electromagnetic coil makes the response time lag, resulting in a further increase in the number of fuel injections Restricted, the repeatability of fuel injection needs to be improved, these are the urgent problems to be solved in the development of injectors to meet the increasingly stringent emission regulations.

Contents of the invention

The object of the present invention is to provide a pressure accumulating and flow-limiting piezoelectric control fuel injector with fast response speed, high control precision, flexible fuel injection rule and stable operation when spraying with small fuel injection volume.

The purpose of the present invention is achieved like this:

The pressure accumulating flow-limiting piezoelectric control fuel injector of the present invention is characterized in that it includes a fuel injector head, a fuel injector body, a valve seat, a needle valve stop block, a nozzle, a current limiting component, a piezoelectric control component, and The injector head is installed on the injector body, the injector head is provided with a main oil inlet hole, and the injector body is provided with a pressure accumulator chamber, the main oil inlet hole communicates with the pressure accumulator chamber, the injector body, valve seat, The needle valve limit block and the nozzle are connected sequentially from top to bottom; the flow limiting assembly includes a limit block, a flow limiting piston, a sliding sleeve, and a ball valve. The flow limiting piston and sliding sleeve are arranged in the pressure accumulator chamber from top to bottom. The ball valve return spring and the support slider are installed inside, the ball valve is installed between the flow limiting piston and the support slider, the damping spring is installed inside the flow limiting piston, the limit block is installed on the flow limit piston, and the limit block is set to communicate with the pressure storage chamber and The first oil inlet hole of the flow-limiting piston is connected with the second oil inlet hole under the sliding sleeve; the piezoelectric control assembly includes a piezoelectric stack and a control valve, the piezoelectric stack is installed in the valve seat, and the control valve is installed in the piezoelectric The fuel injector body is provided with the first oil passage and the oil return port, the valve seat is provided with the second oil passage and the third oil inlet hole, and the needle valve limit block is provided with the third oil passage and the third oil passage. Four oil inlet holes, oil drain port, control valve return spring chamber, the fourth oil circuit is set in the nozzle, the first-fourth oil circuits are connected in sequence, the first oil circuit is connected with the second oil inlet hole, and the control valve resets the spring chamber The control valve return spring is installed inside, and the lower end of the control valve is set in the control valve return spring. The lower part of the control valve is provided with a conical upper sealing surface of the control valve and a lower sealing surface of the control valve. The control valve and the valve seat form a second sealing surface respectively. One oil chamber and the second oil chamber, the first oil chamber is located above the second oil chamber, the third oil inlet hole communicates with the first oil chamber and the second oil passage respectively, the first oil chamber and the second oil chamber are connected to the control valve The upper sealing surface is connected or disconnected with the cooperation of the valve seat, the second oil chamber and the return spring chamber of the control valve are connected or disconnected under the cooperation of the lower sealing surface of the control valve and the needle valve limit block, the control valve return spring chamber, The oil drain port and the oil return port are connected in sequence. A needle valve cavity is set between the needle valve limit block and the nozzle. A needle valve return spring is installed in the needle valve cavity. The upper end of the needle valve is sleeved in the needle valve return spring. Part is located in the nozzle, the fourth oil inlet hole communicates with the second oil chamber and the needle valve chamber respectively, an oil chamber is arranged between the needle valve and the nozzle, the fourth oil passage communicates with the oil chamber, and a spray hole is arranged at the end of the nozzle. The oil chamber and the spray hole are connected or disconnected with the movement of the needle valve.

The present invention may also include:

1. There is a flow-limiting hole connecting the space where the flow-limiting piston and the ball valve are located on the flow-limiting piston.

2. The limit block is fixed in the accumulator chamber through threads.

3. The fuel injector body, valve seat, needle valve limit block and nozzle are connected together by a tight cap set outside it.

The advantage of the present invention is that: the present invention adopts the current limiting component structure, which can effectively prevent the fuel injector from abnormal continuous fuel injection, and ensure the reliability and fuel economy of the fuel injector; the present invention directly controls the needle through the piezoelectric stack. The discharge of high-pressure fuel in the valve cavity, and then directly drive the needle valve, is conducive to the rapid response of the needle valve, the control precision of the needle valve is high, the fuel injection law is flexible, and the power and fuel economy of the diesel engine are effectively improved. ;The structure of the accumulator chamber on the injector body can effectively reduce the pressure fluctuation caused by the working process of the injector, which is conducive to the precise control of the fuel injection volume, and can further improve the work of the fuel injector in the small fuel injection volume condition. fuel injection stability.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Figure 2 is an enlarged view of the structure of the current limiting assembly of the present invention;

Fig. 3 is an enlarged view of the structure of the piezoelectric control assembly of the present invention.

detailed description

The present invention is described in more detail below in conjunction with accompanying drawing example:

1-3, the pressure accumulating flow-limiting piezoelectric control injector of the present invention consists of an injector head 1, an injector body 2, a current limiting assembly 3, a piezoelectric control assembly 5, a needle valve return spring 6, The positioning pin 7, the nozzle 10, the needle valve 11, the needle valve limit block 13, the valve seat 14, the tight cap 15 and the seal ring 16 are composed. The fuel injector body 2 is provided with a pressure accumulator chamber 17, which communicates with the main oil inlet hole 18 on the injector head 1. The oil hole 28 communicates with the pressure accumulator chamber 17, and the oil chamber in the flow-limiting piston 27 is equipped with a damping spring 20, and the flow-limiting piston 27 has a flow-limiting hole 26, and the flow-limiting piston 27 is connected to it as the valve seat of the ball valve 21, as The sliding sleeve 25 of the valve seat of the ball valve 21 is fixed in the injector body 2, the supporting slider 22 can slide back and forth in the sliding sleeve 25, the ball valve return spring 23 presses the supporting slider 22 to the ball valve 21 tightly, and the upper end of the control valve 30 presses Close to the lower end surface of the piezoelectric stack 39, when no voltage is applied to the piezoelectric stack 39, the lower sealing surface 33 of the control valve is pressed tightly to the lower sealing valve seat of the needle valve limit block 13, the first oil chamber 31 and the second oil chamber The cavity 32 communicates, the first oil cavity 31 communicates with the high-pressure oil circuit on the injector body 2 through the third oil inlet hole 38, the needle valve 11 is pressed onto the needle valve seat of the nozzle 10 by the needle valve return spring 6, The needle valve chamber 12 communicates with the second oil chamber 32 through the fourth oil inlet hole 35 of the needle valve limit block 13. After the piezoelectric stack 39 is loaded with a voltage signal, the control valve 30 moves upward due to the elastic force of the control valve return spring 36. lift, the upper sealing surface 37 of the control valve is pressed against the upper sealing seat surface of the valve seat 14, the first oil chamber 31 is no longer communicated with the second oil chamber 32, the second oil chamber 32 is communicated with the drain port 34, and the control The lifting and seating of the valve 30 respectively control the on-off of the first oil chamber 31 and the second oil chamber 32 and the second oil chamber 32 and the oil drain port 34, and then control the needle valve chamber 12 and the high and low pressure oil circuit in the injector. on and off.

Figure 1 is a schematic diagram of the overall structure of the pressure accumulator and flow-limiting piezoelectric control injector of the present invention, including 1 injector head, 2 injector body, 3 current limiting assembly, 5 piezoelectric control assembly, and 6 needle valve return spring , 7 positioning pins, 10 nozzles, 11 needle valves, 13 needle valve limit blocks, 14 valve seats, 15 tight caps and 16 sealing rings. The fuel injector body 2 is provided with a pressure accumulator chamber 17, and the injector head 1 is provided with a main oil inlet hole 18, the pressure accumulator chamber 17 communicates with the main oil inlet hole 18, and the main oil inlet hole 18 is connected with the high-pressure oil inlet pipe. The fuel injector head 1 is fastened to the fuel injector body 2, and the oil drain port 34 communicates with the oil return port 4 through the low-pressure oil passage on the fuel injector body 2, and the oil return port 4 is connected with the low-pressure fuel pipe. The needle valve return spring 6 presses the needle valve 11 to the needle valve seat of the nozzle 10, an oil chamber 8 is formed between the needle valve 11 and the nozzle 10, the needle valve chamber 12 communicates with the fourth oil inlet hole 35, and the third inlet The oil hole 38 communicates with the high-pressure oil circuit on the injector body 2, and the piezoelectric stack 39 controls the first oil chamber 31 and the second oil chamber 32 and the second oil chamber 32 and the second oil chamber 32 by controlling the lifting and seating of the control valve 30. The on-off of the oil drain port 34 further realizes the switching between the high and low pressure oil circuits in the fuel injector of the present invention. The accumulator chamber 17 in the fuel injector body 2 can reduce the fuel pressure fluctuation caused by the working process of the present invention, which is beneficial to the precise control of the fuel injection quantity by the electronic control unit, especially for the small fuel quantity control accuracy can be significantly improved . At the same time, when the present invention is applied to a high-pressure common rail fuel injection system, the pressure stabilizing effect of the accumulator chamber 17 can reduce the size of the common rail pipe of the diesel engine to a certain extent, which is beneficial to reduce the high-strength material of the common rail pipe. Requirements, improve its service life, and save the installation space of the common rail pipe.

Limiting block 19, damping spring 20, ball valve 21, support slider 22, ball valve return spring 23, second oil inlet hole 24, sliding sleeve 25, flow limiting hole 26, flow limiting piston 27 and first oil inlet hole 28 are common The current limiting assembly 3 constituting the pressure accumulator current limiting piezoelectric control injector is shown in FIG. 2 . The two ends of the ball valve 21 use the flow-limiting piston 27 and the supporting slide block 22 as valve seats respectively, and the damping spring 20 is installed in the oil cavity in the flow-limiting piston 27, and the oil cavity in the flow-limiting piston 27 passes through the limit block 19. The first oil inlet hole 28 is in communication with the pressure accumulator chamber 17, the flow-limiting piston 27 has a flow-limiting hole 26, and the support slider 22 is pressed to the ball valve 21 by the ball valve return spring 23, as a sliding sleeve 25 on the seat surface of the ball valve 21 It is fixed in the injector body 2, the supporting slider 22 can slide back and forth in the sliding sleeve 25, and the second oil inlet hole 24 is respectively connected with the high-pressure fuel oil channel in the injector body 2 and the high pressure where the ball valve return spring 23 is located. The oil chambers are connected, the supporting slider 22 has an axial fuel through hole, and the end of the supporting slider 22 close to the ball valve 21 has a lateral fuel through hole, and the axial fuel through hole is connected with the lateral fuel through hole as a damping The limiting block 19 of the spring seat of the spring 20 limits the maximum upward displacement of the flow limiting piston 27, and the limiting block 19 is fixed in the injector body 2 by threads. When the fuel injector injects normally, the high-pressure fuel in the fuel injector is sprayed into the combustion chamber through the nozzle hole 9 for combustion. Due to the fuel injection, the pressure of the fuel in the cavity where the ball valve return spring 23 is located decreases, and due to the flow restriction hole 26 For the throttling effect of the fuel, the fuel pressure in the chamber where the damping spring 20 is located is relatively high, and the pressure difference between the two ends of the restrictor piston 27 drives the ball valve 21 and the support slider 22 to move downward for a certain distance to compensate for the amount of fuel injected. But the ball valve 21 will not sit down on the valve seat of the sliding sleeve 22, that is, the ball valve 21 is not sealed. The piston 27, the ball valve 21 and the support slider 22 return to the initial position; when the nozzle hole 9 is normally open, the injector continuously injects abnormal fuel, and the quality of the fuel flowing out of the pressure accumulator chamber 17 exceeds the maximum fuel quantity, Because the amount of oil flowing through the flow-limiting hole 26 is too large and the flow velocity is too fast, the flow-limiting piston 27 is quickly pressed down from the rest position due to the pressure difference at both ends, and the ball valve 21 is pressed to the valve seat of the sliding sleeve 25 thereupon, and Seal the seat surface. At this time, the high-pressure fuel in the accumulator chamber 17 no longer flows to the second oil inlet 24 through the first oil inlet hole 28 and the restrictor hole 26 until the injector stops abnormal fuel injection, effectively avoiding The waste of fuel when the injector does not work normally is beneficial to the fuel economy and the reliability of the injector.

Piezoelectric stack electrical connector 29, control valve 30, first oil chamber 31, second oil chamber 32, control valve lower sealing surface 33, oil drain port 34, fourth oil inlet hole 35, control valve reset spring 36, control valve The upper sealing surface 37 , the third oil inlet hole 38 and the piezoelectric stack 39 jointly constitute the piezoelectric control assembly 5 of the pressure accumulating current-limiting piezoelectric control injector, as shown in FIG. 3 . The piezoelectric stack 39 is connected to the engine electronic control unit through the piezoelectric stack electrical connector 29, and then controls the rise and fall of the control valve 30. The upper end surface of the control valve 30 is pressed to the lower end surface of the piezoelectric stack 39 by the control valve return spring 36, The third oil inlet hole 38 communicates with the first oil chamber 31 and the high-pressure fuel oil passage on the injector body 2, the fourth oil inlet hole 35 communicates with the second oil chamber 32 and the needle valve chamber 12, and there is a control valve on the control valve 30. There are two sealing surfaces, the upper sealing surface 37 and the lower sealing surface 33 of the control valve, the sealing seat surface on the needle valve limit block 13 matches with the lower sealing surface 33 of the control valve, the sealing seat surface on the valve seat 14 and the upper sealing surface of the control valve Face 37 cooperates. When no voltage is applied to the piezoelectric stack 39, as shown in Figure 3, the control valve 30 is pressed onto the valve seat of the needle valve limit block 13, the lower sealing surface 33 of the control valve is sealed, the upper sealing surface 37 of the control valve is opened, and the second The second oil chamber 32 is separated from the oil drain port 34, the first oil chamber 31 communicates with the second oil chamber 32, and the high-pressure fuel flowing down from the accumulator chamber 17 flows into the first oil chamber 31 through the third oil inlet hole 38, and then It flows into the second oil chamber 32 and flows into the needle valve chamber 12 through the fourth oil inlet hole 35. At this time, the resultant force of the hydraulic pressure on the upper surface of the needle valve 11 and the elastic force of the needle valve return spring 6 is greater than that on the lower surface of the needle valve 11. Therefore, the needle valve 11 does not lift when seated, and the fuel injector does not inject fuel; after the piezoelectric stack 39 is powered, due to the inverse piezoelectric effect of the piezoelectric crystal stack, the piezoelectric stack 39 deforms and shortens, and the control valve 30 Under the elastic force of the return spring 36 of the control valve, it moves upward accordingly, the upper sealing surface 37 of the control valve is sealed, the lower sealing surface 33 of the control valve is opened, the first oil chamber 31 is separated from the second oil chamber 32, and the second oil chamber 32 is connected to the second oil chamber. The oil drain port 34 communicates, the needle valve chamber 12 communicates with the oil drain port 34 through the fourth oil inlet hole 35, and the high-pressure fuel in the needle valve chamber 12 flows back into the fuel tank through the oil return port 4 communicated with the low-pressure oil pipe, At this time, the fuel oil pressure on the upper surface of the needle valve 11 decreases rapidly, and when the resultant force of it and the spring force of the needle valve return spring 6 is smaller than the hydraulic pressure on the lower surface of the needle valve 11, the needle valve 11 is lifted upwards, The injector starts to inject fuel. The lifting and seating of the control valve 30 control the connection between the first oil chamber 31 and the second oil chamber 32 and the second oil chamber 32 and the oil drain port 34, thereby controlling the connection between the needle valve chamber 12 and the high-pressure accumulator chamber 17 or the low-pressure oil tank. On and off, so as to realize the conversion of high and low pressure fuel oil circuits in the injector.

When the diesel engine is working, high-pressure fuel enters the pressure accumulator chamber 17 in the injector body 2 through the main oil inlet hole 18 on the injector head 1, and enters the fuel chamber through a part of the flow limiting assembly 3 connected with the pressure accumulator chamber 17 8, the other part enters the needle valve chamber 12 through the third oil inlet hole 38, the first oil chamber 31, the second oil chamber 32, and the fourth oil inlet hole 35 respectively. When the piezoelectric stack 39 receives the energized fuel injection signal from the electronic control unit and is deformed and shortened due to the inverse piezoelectric effect, the control valve 30 moves upwards under the elastic force of the control valve return spring 36, and the upper sealing surface 37 of the control valve is sealed. The first oil chamber 31 is no longer in communication with the second oil chamber 32, the lower sealing surface 33 of the control valve is opened, the second oil chamber 32 is in communication with the oil drain port 34, the oil drain circuit is opened, and the high-pressure fuel in the needle valve chamber 12 passes through the injection nozzle. The oil return port 4 on the oiler body 2 enters the low-pressure oil circuit. At this time, the fuel pressure in the needle valve cavity 12 drops rapidly, the fuel pressure in the oil storage cavity 8 is greater than the fuel pressure in the needle valve cavity 12, and the needle valve 11 is affected. The upward hydraulic pressure is greater than the resultant force of the downward hydraulic pressure and the elastic force of the needle valve return spring 6, the needle valve 11 is lifted away from the needle valve seat surface, and the injector starts to inject oil; when the piezoelectric stack is disconnected When the fuel injection voltage is 39, the piezoelectric stack 39 returns to its original length, the control valve 30 moves downward, the lower sealing surface 33 of the control valve seals, the second oil chamber 32 is no longer connected to the oil drain port 34, and the oil drain circuit is closed. The upper sealing surface 37 of the control valve is opened, the first oil chamber 31 communicates with the second oil chamber 32, and the high pressure in the accumulator chamber 17 flows through the third oil inlet hole 38, the first oil chamber 31, the second oil chamber 32, The fourth oil inlet hole 35 enters the needle valve chamber 12 again. At this time, the fuel pressure in the needle valve chamber 12 and the fuel oil pressure in the oil storage chamber 8 are restored to be equal, and the needle valve 11 is under the action of the elastic force of the needle valve return spring 6. The seat is dropped, and the fuel injection of the fuel injector is finished.

It can be seen from the above working process that during the fuel injection process of the pressure accumulator and flow-limiting piezoelectric control injector of the present invention, the action response of the needle valve 11 is directly driven by high-pressure fuel and piezoelectric stack, with fast action speed and high control precision. The fuel injection rules are flexible and changeable, which can effectively improve the power and fuel economy of the diesel engine, so that the diesel engine can meet more stringent emission regulations; At the same time, when the fuel injector of the present invention is applied to the common rail fuel injection system, it can reduce the structural size of the common rail pipe, thereby reducing the material strength requirements of the common rail pipe and improving its service life; The structure can effectively avoid the decline of fuel economy caused by the abnormal continuous fuel injection of the fuel injector, and ensure the reliability of the work of the present invention.

The pressure accumulating flow-limiting piezoelectric control fuel injector of the present invention includes a fuel injector head, a fuel injector body, a current limiting assembly, a piezoelectric control assembly, a needle valve return spring, a positioning pin, a nozzle, a needle valve, and a needle valve limiter. Block, seat, cap and seal. There is a pressure accumulator on the injector body, and the pressure accumulator is respectively connected with the main oil inlet hole on the injector head and the first oil through hole on the limit block, and the flow limiting component is installed in the injector body. The lower end of the flow limiting assembly communicates with the fuel oil passage in the injector body, the needle valve chamber communicates with the second oil chamber through the fourth oil inlet hole on the needle valve limit block, and the first oil chamber communicates with the second oil chamber through the third oil inlet hole on the valve seat. The oil inlet hole is connected with the high-pressure fuel oil circuit in the injector body, and the oil drain port is connected with the oil return port through the low-pressure oil circuit in the injector body. upper end.

The flow limiting assembly includes a limiting block, a damping spring, a ball valve, a supporting slider, a ball valve return spring, a sliding sleeve and a flow limiting piston. The oil chamber in the flow-limiting piston communicates with the pressure storage chamber through the first oil inlet hole on the limiting block. The damping spring is installed in the oil chamber in the flow-limiting piston. The valve seat as the ball valve is connected with it, the sliding sleeve as the valve seat of the ball valve is fixed in the injector body, the supporting slider can slide back and forth in the sliding sleeve, the ball valve return spring presses the supporting slider to the ball valve, the second oil inlet hole They are respectively connected with the cavity where the return spring of the ball valve is located and the high-pressure fuel oil circuit in the injector body. connected.

There are at least two first oil inlet holes and they are arranged symmetrically to the axis of the injector. If there are at least one restrictor hole, they are arranged symmetrically to the axis of the injector. The total cross-sectional area of the first oil inlet holes is greater than the limit The sum of the cross-sectional areas of the orifices.

There is one axial fuel through-hole on the support slide, and at least two lateral fuel through-holes on the support slide are arranged symmetrically to the axis of the injector.

The piezoelectric control assembly includes piezoelectric stack electrical connectors, control valves, control valve return springs, and piezoelectric stacks. The control valve has two sealing surfaces, the upper sealing surface of the control valve and the lower sealing surface of the control valve. The upper end surface of the control valve is compressed to the lower end surface of the piezoelectric stack. On the lower sealing valve seat of the needle valve limit block, the first oil chamber communicates with the second oil chamber; after the piezoelectric stack is powered, the control valve lifts up, and the upper sealing surface of the control valve is pressed against the upper sealing surface of the valve seat Above, the first oil chamber is no longer in communication with the second oil chamber, and the second oil chamber is in communication with the oil drain port. Lifting and seating of the control valve respectively control the on-off of the needle valve chamber and the first oil chamber or the oil drain port.

Claims (5)

1. pressure accumulation current-limiting type piezoelectric control fuel injector, is characterized in that: comprise injector head, oil injector body, valveSeat, needle-valve limited block, nozzle, current limliting assembly, piezoelectricity Control Component, injector head is arranged on oil injector bodyUpper, main fuel feed hole is set in injector head, pressure accumulation chamber is set, main fuel feed hole and pressure accumulation chamber phase in oil injector bodyLogical, oil injector body, valve seat, needle-valve limited block, nozzle are connected from top to bottom successively; Current limliting assembly comprises limitPosition piece, current limliting piston, sliding sleeve, ball valve, current limliting piston and sliding sleeve are arranged in pressure accumulation chamber from top to bottom, slidingMounting ball valve back-moving spring and support slipper in cover, ball valve is arranged between current limliting piston and support slipper, limitStream is installed damping spring in piston, mounting limit piece on current limliting piston, on limited block, arrange be communicated with pressure accumulation chamber andThe first fuel feed hole of current limliting piston, sliding sleeve below arranges the second fuel feed hole communicating with it; Piezoelectricity Control ComponentComprise piezoelectric pile, control valve, piezoelectric pile is arranged in valve seat, control valve be arranged on the below of piezoelectric pile and withIt is connected, and the first oil circuit, oil return opening are set in oil injector body, and the second oil circuit, the 3rd oil-feed are set in valve seatHole, arranges the 3rd oil circuit, the 4th fuel feed hole, drain tap, control valve back-moving spring chamber in needle-valve limited block,The 4th oil circuit is set in nozzle, and first-, tetra-oil circuits communicate successively, and the first oil circuit communicates with the second fuel feed hole,Control valve back-moving spring is installed control valve back-moving spring in chamber, and the bottom of control valve is placed on control valve reset bulletIn spring, the bottom of control valve arranges sealing surface and control valve lower sealing surface on the control valve of taper, control valve withBetween valve seat, form respectively the first oil pocket and the second oil pocket, the first oil pocket is positioned at the second oil pocket top, and the 3rd entersOilhole communicates with the first oil pocket and the second oil circuit respectively, the first oil pocket and the second oil pocket sealing surface on control valveBe communicated with or disconnect with under the cooperation of valve seat, the second oil pocket and control valve back-moving spring chamber are in control valve lower sealing surfaceBe communicated with or disconnect with under the cooperation of needle-valve limited block, control valve back-moving spring chamber, drain tap, oil return opening are successivelyCommunicate, needle-valve chamber is set between needle-valve limited block and nozzle, needle-valve back-moving spring is installed, needle-valve in needle-valve chamberUpper end be placed in needle-valve back-moving spring, needle-valve remainder is positioned in nozzle, the 4th fuel feed hole respectively withThe second oil pocket and needle-valve chamber communicate, and Sheng oil pocket is set between needle-valve and nozzle, and the 4th oil circuit communicates with containing oil pocket,Nozzle-end arranges spray orifice, contains oil pocket and spray orifice and is communicated with or disconnects with the mobile of needle-valve.

2. pressure accumulation current-limiting type piezoelectric control fuel injector according to claim 1, is characterized in that: current limliting is livedHave the metering hole that is communicated with current limliting piston and space, ball valve place beyond the Great Wall.

3. pressure accumulation current-limiting type piezoelectric control fuel injector according to claim 1 and 2, is characterized in that: limitPosition piece is fixed in pressure accumulation chamber by screw thread.

4. pressure accumulation current-limiting type piezoelectric control fuel injector according to claim 1 and 2, is characterized in that: sprayOil body, valve seat, needle-valve limited block, nozzle link together by the tight cap that is enclosed within its outside.

5. pressure accumulation current-limiting type piezoelectric control fuel injector according to claim 3, is characterized in that: fuel injectorBody, valve seat, needle-valve limited block, nozzle link together by the tight cap that is enclosed within its outside.