JP2009257309A - Injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate opening/closing a needle valve by reducing pressure applied to a needle valve back part when the needle valve is opened, and inject fuel at high injection pressure with good controllability without increasing attraction force, in an injector using a method for directly driving the needle valve by an electromagnetic drive part. <P>SOLUTION: In the injector I, an armature part 1a is integrally provided in a base end part of the needle valve 1 stored in a bar-shaped body 2, and attraction is enabled by a solenoid 5 in the electromagnetic drive part. In the armature part 1a, back pressure of a pressure control chamber 7 communicated with a high-pressure fuel supply passage is applied, and a control valve 6 for opening/closing a space between the pressure control chamber 7 and a low-pressure fuel outflow passage is attracted and driven by the solenoid 5. When the back pressure of the pressure control chamber 7 is declined to predetermined pressure, the needle valve 1 is lifted by the attraction force of the solenoid 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injector used in a fuel injection device for an internal combustion engine for automobiles, and more particularly to an accumulator type direct acting injector.

  For example, a common rail type fuel injection device for accumulating high pressure fuel on a common rail common to each cylinder is known for diesel engines. Conventionally, an injector of a common rail type fuel injection device has been provided with an electromagnetic control valve having a three-way valve structure by supplying high pressure fuel from a common rail to a nozzle hole and supplying it to a back pressure chamber of a needle valve that opens the nozzle hole. What is used and controlled is adopted. The electromagnetic control valve houses the valve body in a valve chamber communicating with the back pressure chamber, and drives the valve body with a solenoid to selectively communicate the valve chamber with either the high pressure fuel supply path or the low pressure fuel outflow path. Then, increase or decrease the pressure in the back pressure chamber.

By the way, in recent years, a direct-acting injector in which a needle valve is directly driven by a solenoid has been proposed in order to reduce the size of the apparatus and reduce the number of parts (for example, Patent Documents 1 and 2). The direct acting system is advantageous when liquefied gas fuel such as dimethyl ether (DME) or liquefied petroleum gas (LPG), which is considered as an alternative fuel for light oil, is used, and does not use liquefied gas fuel that is easily vaporized as control oil. For this reason, it is possible to avoid the entire apparatus from becoming large.
JP-A-2005-291128 JP 2003-214287 A

  As a linear motion injector, for example, in Patent Document 1, an armature integrated with a needle valve is stored in an armature chamber, and an external fuel supply path is connected to a fuel flow path around the needle valve via the armature chamber. What has been made to be disclosed is disclosed. In this case, since the fuel is always supplied after passing through the armature chamber, there is an advantage that the fuel is less likely to stay in the injector and the recovery device can be omitted.

  In Patent Document 2, a rod member is connected to the end of the needle valve on the side opposite to the injection hole, and an armature is provided around the rod member, while the end of the needle valve on the side opposite to the injection hole is provided by fuel in the armature chamber. It is described that a reduction means for reducing the pressure acting on the liquid crystal is provided. The reducing means is, for example, a low-pressure chamber that is formed between the needle valve and the rod member and communicates with the fuel tank, and reduces the pressure acting on the area of the end surface of the low-pressure chamber to facilitate valve opening.

  Since the injector of Patent Document 1 always applies a high pressure to the back of the needle valve, when the valve is opened, a large suction force is required to push away the force corresponding to the high pressure receiving area. In Patent Document 2, the pressure applied to the back portion of the needle valve is reduced, but only a small area of the end face of the low-pressure chamber can be reduced. For this reason, when the fuel pressure is further increased by increasing the injection pressure, the suction force required for the electromagnetic drive unit increases, and the drive force required for opening the valve cannot be sufficiently reduced. As a result, there has been a problem that the electromagnetic drive unit becomes larger and the cost rise cannot be avoided, or the needle valve cannot be opened / closed at a high injection pressure due to restrictions on the injector space and load current.

  In order to solve the above problems, the present invention provides a direct-acting injector that drives a needle valve by an electromagnetic drive unit, by sufficiently reducing the pressure of fuel acting on the back of the needle valve, and with a small suction force of the needle valve. The purpose is to enable an on-off valve, thereby enabling fuel to be injected with high injection pressure and controllability without increasing the size of the electromagnetic drive unit, and to realize a small, low-cost and high-performance injector. To do.

According to the first aspect of the present invention, the needle valve accommodated in the rod-shaped body is driven by suction by the electromagnetic drive unit, the nozzle hole provided at the tip of the body is opened and closed, and the high-pressure fuel supplied from the high-pressure fuel supply path is An injector for injection,
An armature portion provided integrally with the base end portion of the needle valve is accommodated in a pressure control chamber communicating with the high pressure fuel supply path, and a back pressure is applied to the needle valve.
The electromagnetic drive unit is provided with a control valve that opens and closes between the pressure control chamber and the low pressure fuel outflow passage.
The needle drive valve is lifted by a suction force acting on the needle valve in a state where the pressure of the pressure control chamber is lowered by opening the control valve by the electromagnetic drive unit.

  When the electromagnetic drive unit sucks and drives the control valve, the control valve is opened, the pressure control chamber and the low pressure fuel outflow passage are communicated, and the pressure is reduced. As a result, the back pressure of the needle valve is set to a predetermined pressure or less, and further, the needle valve is lifted by the suction force of the electromagnetic drive unit, and fuel can be injected.

  In the present invention, by combining the suction force of the electromagnetic drive unit and the pressure control of the pressure control chamber that applies back pressure to the needle valve, the direct acting needle valve can be opened and closed without increasing the size of the electromagnetic drive unit. it can. As a result, the direct-acting needle valve can be injected at a high injection pressure, the valve lift controllability can be improved, and an efficient and stable fuel injection can be realized.

  According to a second aspect of the present invention, the electromagnetic drive unit includes a single solenoid, and the needle valve is lifted by the suction force of the solenoid that drives the control valve by suction.

  One solenoid forms a magnetic circuit for the control valve and the needle valve, and the control valve is opened to reduce the pressure in the pressure control chamber, and the back pressure of the needle valve is kept below a predetermined pressure. The needle valve can be set to open by suction force. At this time, since the suction force increases with the lift, the needle valve lifts rapidly, and a boot-type injection characteristic is obtained.

  According to a third aspect of the present invention, the electromagnetic drive unit includes two solenoids, the control valve is opened by the suction force of the first solenoid, the pressure control chamber communicates with the low-pressure fuel outflow passage, The needle valve is lifted by the suction force of the second solenoid in a state where the pressure is lower than a predetermined pressure.

  A magnetic circuit of the control valve and the needle valve can be formed by two solenoids, and each can be controlled independently. Efficient fuel injection can be performed by independently controlling the energization timing of the two solenoids.

  According to a fourth aspect of the present invention, in the configuration according to the third aspect, the electromagnetic drive unit stops energizing the first solenoid after energizing the second solenoid.

  Specifically, the control valve is energized only when the needle valve is opened, and the energization to the control valve is stopped after the valve is opened, thereby reducing the amount of leakage and performing efficient fuel injection. it can.

  According to a fifth aspect of the present invention, in the electromagnetic drive unit having the configuration according to the second aspect, the magnetic circuit that applies an attractive force to the control valve and the needle valve includes the magnetic body portion of the control valve and the needle valve. Pass in series.

  Since the magnetic circuit generated around the solenoid passes through the magnetic body of the control valve and the needle valve in series, a strong suction force can be generated without dispersing the magnetism. The force required to open the valve can be reliably generated.

  According to a sixth aspect of the present invention, in the configuration according to the fifth aspect, the needle valve is accommodated in the lower half of the body, the electromagnetic drive unit is accommodated in the upper half, and the control valve is disposed above the needle valve. Are arranged coaxially, and the outer periphery of the control valve made of a magnetic material is held by a cylindrical portion made of a non-magnetic material, while the central portion of the top wall of the pressure control chamber facing the control valve is made of a magnetic material. And the outer peripheral portion of the top wall of the pressure control chamber located between the solenoid and the armature is made of a non-magnetic material.

  A non-magnetic material is disposed on the outer periphery of the control valve and the top wall of the pressure control chamber, and the magnetic body portion of the control valve and the needle valve are placed close to each other, thereby easily forming a magnetic circuit passing through the control valve and the needle valve in series. And the armature part provided in the base end part of a needle valve can be rapidly driven with a bigger suction force. Thus, it is not necessary to change the solenoid specifications or increase the solenoid current in order to increase the suction force, and the needle valve can be directly controlled at a high injection pressure.

(First embodiment)
Hereinafter, a first embodiment to which the present invention is applied will be described with reference to FIGS. FIG. 1 is an overall cross-sectional view showing a schematic configuration of an injector I of the present invention, FIG. 2 is an enlarged cross-sectional view showing the main part configuration, and FIG. 3 is a time chart showing an example of fuel injection control. The injector I is applied to, for example, a common rail fuel injection device of a diesel engine, and is provided in a one-to-one correspondence with each cylinder of the engine. A common rail (not shown), which is a pressure accumulating chamber common to each injector I, accumulates fuel pressurized to a high pressure by a high-pressure supply pump (not shown), and the optimal injection amount and injection according to the engine operating state The ECU (not shown) controls the entire apparatus so that it is time. As fuel accumulated in the common rail, liquefied fuel such as dimethyl ether (DME) and liquefied petroleum gas (LPG) can be used or used together with general light oil.

  As shown in FIG. 1, the injector I slidably holds a needle valve 1 in a lower half portion of a body 2 having a substantially rod-like overall shape. The body 2 constitutes a nozzle portion 2a having a small diameter at the lower end portion, projects into a combustion chamber (not shown) of the corresponding cylinder, and injects fuel from the nozzle hole 3 at the tip. A high-pressure pipe 21 and a low-pressure pipe 22 protrude from the side of the upper end of the body 2. The high-pressure pipe 21 serves as a high-pressure fuel supply path (not shown) leading to an external common rail, and the low-pressure pipe 22 serves as a fuel. A low-pressure fuel outflow passage (not shown) leading to a tank (not shown) is connected to each other. A high pressure channel 23 and a low pressure channel 24 extending in the axial direction are formed in the body 2, and are connected to the high pressure pipe 21 and the low pressure pipe 22, respectively.

  The body 2 is usually divided into distance pieces for forming a plurality of body members, flow paths, and the like, and has a structure in which these are joined together by a retaining nut. The whole structure is simplified as one body.

  In the lower half of the body 2 of the injector I, an oil reservoir chamber 4 is formed on the outer periphery of the needle valve 1, and a plurality of injection holes 3 are formed through the wall of the sack portion 31 provided at the lower end of the oil reservoir chamber 4. Has been. A high pressure flow path 23 is connected to the oil reservoir 4 and high pressure fuel (Pcr) is introduced from the common rail. In the state shown in the drawing, the needle valve 1 is in contact with the nozzle sheet 41 formed at the boundary between the oil reservoir 4 and the sac portion 31 at the tip end (lower end in the figure), and closes the nozzle hole 3. At this time, the pressure of the oil reservoir 4 acts only on the outer side of the nozzle sheet 41 (cross-sectional area As) on the tip surface of the needle valve 1. That is, the load in the valve opening direction (upward in the figure) by the oil reservoir chamber 4 is Fp = Pcr × (Ap−As) when attempting to open the valve from the valve-closed state (valve-closed state). When the valve is to be closed (opened state), it is expressed as Fp = Pcr × Ap.

  In the upper half of the body 2, a solenoid 5 and a control valve 6 constituting an electromagnetic drive unit are accommodated. The solenoid 5 is held in a coil case 52 disposed around a cylindrical nonmagnetic body 51 as a cylindrical portion, and is a plunger that moves within the cylinder of the cylindrical nonmagnetic body 51 with its inner peripheral surface serving as a guide surface. The control valve 6 is held. A pressure control chamber 7 is formed below the solenoid 5 and the control valve 6 constituting the electromagnetic drive unit and above the oil reservoir chamber 4.

  The needle valve 1 is located in the pressure control chamber 7 with a base end portion (upper end portion in the figure) passing through the top wall of the oil reservoir chamber 4. A large-diameter armature portion 1 a is integrally provided at the proximal end portion of the needle valve 1 and faces the lower end magnetic pole surface of the solenoid 5. The pressure control chamber 7 is always in communication with the high-pressure channel 23 via the inlet throttle 8 that opens to the side surface, and is the pressure of fuel introduced from the high-pressure channel 23 and is equivalent to the pressure (Pcr) of the oil reservoir chamber 4. High pressure (Pcr ′). This pressure acts as a back pressure (Pcr ′ × Ap) on the needle valve 1 (cross-sectional area Ap) integral with the armature portion 1a. Further, a spring 12 is disposed between the flange 11 projecting from the outer periphery of the lower end of the armature portion 1a and the upper wall of the pressure control chamber 7, and the needle valve 1 is closed by the spring force (Fsp) (see FIG. (Below).

  On the other hand, an outlet throttle 9 is provided at the center of the top surface of the pressure control chamber 7. The outlet throttle 9 is opened and closed by a valve body 61 provided at the lower end portion of the control valve 6 to switch the communication between the pressure control chamber 7 and the low-pressure channel 24 and shut off, and the pressure (Pcr ′) in the pressure control chamber 7. Increase or decrease. That is, the load in the valve closing direction (Fp ′ = Pcr ′ × Ap + Fsp) due to the oil pressure acting as a back pressure on the needle valve 1 (cross-sectional area Ap) and the urging force of the spring 12 is increased or decreased. The control valve 6 is urged downward by a spring 62 disposed above the control valve 6, and the valve body 61 is in a lower end position where the outlet throttle 9 is closed while the solenoid 5 is not energized. The in-cylinder space of the cylindrical non-magnetic body 51 in which the control valve 6 is accommodated and the space in which the spring 62 is accommodated communicate with the low-pressure channel 24. The control valve 6 and the outlet throttle / needle valve 1 are located on the same axis.

  The electromagnetic drive unit opens the outlet throttle 9 when the solenoid 5 drives the control valve 6 by suction. For example, the control valve 6 is provided with a concave portion on the bottom surface facing the outlet throttle 9 to hold a valve body 61 having a substantially hemispherical diameter larger than the diameter of the outlet throttle 9. A simple bottom surface can close the outlet throttle 9. In this embodiment, the solenoid 5 is shared by the control valve 6 and the needle valve 1, and the suction force of the solenoid 5 is also applied to the armature portion 1 a of the needle valve 1. The suction force (Fs) by the solenoid 5 acts in the valve opening direction of the needle valve 1. Further, the inlet throttle 8 and the outlet throttle 9 are normally set so that the diameter of the outlet throttle 9> the diameter of the inlet throttle 8. For this reason, when the outlet throttle 9 is opened, the fuel flows out, the pressure in the pressure control chamber 7 decreases, and the pressure applied to the back of the needle valve 1 decreases. When the pressure control chamber 7 is reduced to a predetermined pressure, the solenoid 5 can suck the armature portion 1a, and the needle valve 1 is raised to open the nozzle hole 3.

The operation of the injector I of the present invention will be described in detail with reference to FIGS.
In the configuration of the injector I in FIG. 1, when the energization is turned on from the state in which the solenoid 5 is not energized, as shown in FIG. 2, a magnetic circuit S1 passing through the control valve 6 is generated and an attractive force is generated. As shown in FIG. 3, the suction force increases in proportion to the current value, and lifts the control valve 6. The main body of the control valve 6 is held in the cylinder of the solenoid 5, the pressure of the high-pressure fuel is not acting, the lift can be lifted with a slight suction force, and the lift starts immediately when the solenoid 5 is energized.

  In FIG. 2, when the spring force of the spring 62 acting on the valve body 61 that closes the outlet throttle 9 is released by the lift of the control valve 6, the pressure (Pcr ′) of the pressure control chamber 7 that is high pressure is released. ), The valve body 61 is pushed up. As a result, the fuel in the pressure control chamber 7 flows out from the outlet throttle 9 to the low pressure passage 24, and the pressure gradually decreases. As shown in FIG. 3, the pressure Pcr ′ in the pressure control chamber 7 decreases until the inflow amount from the inlet throttle 8 and the outflow amount to the outlet throttle 9 are balanced, and becomes a constant pressure.

  On the other hand, a magnetic circuit S2 passing through the armature portion 1a is generated, and an attractive force is generated. At this time, the oil pressure Fp (= Pcr × (Ap−As)) of the oil reservoir chamber 4 acts in the valve opening direction on the needle valve 1 in addition to the attractive force Fs by the magnetic circuit S2. That is, as shown in FIG. 3, as the force acting on the needle valve 1, the resultant force of the oil pressure in the oil reservoir 4 and the attractive force generated in the magnetic circuit S2 (force Fp + Fs acting on the valve opening side) is upward. The resultant force of the oil pressure by the pressure control chamber 7 and the spring force of the spring 12 (force Fp ′ = Pcr ′ × Ap + Fsp acting on the valve closing side) acts downward.

  Since this suction force Fs is smaller than the force Fp ′ in the valve closing direction acting on the back of the needle valve 1 in the initial stage of energization, the needle valve 1 is lifted even if the oil pressure Fp in the oil reservoir 4 is taken into account. It does n’t work. As the current of the solenoid 5 increases, the attractive force Fs gradually increases. Since the current value of the solenoid 5 necessary to maintain the control valve 6 after the lift of the control valve 6 is smaller than the current value necessary for suction (indicated by an arrow A in the figure), the current required for the solenoid 5 The value is obtained by adding the current for suction of the needle valve 1 to the current for maintaining the lift of the control valve 6. Further, since the spring force (Fsp) of the spring 12 is sufficiently small with respect to the oil pressure, the force Fp acting on the valve closing side will be described below as the oil pressure in the pressure control chamber 7 as appropriate.

  As the solenoid current increases, the suction force Fs increases, and the pressure Pcr ′ of the pressure control chamber 7 decreases to a constant pressure. Therefore, the two balance each other at a certain point, and when the suction force further increases, the valve opens. The force Fp + Fs exceeds the force Fp ′ acting on the valve closing side (Fp ′ ≦ Fp + Fs). As a result, the solenoid 5 sucks and drives the armature portion 1 a, the needle valve 1 is opened, and the fuel in the oil reservoir chamber 4 is injected from the injection hole 3. When the needle valve 1 starts to lift, the fuel in the oil reservoir chamber 4 also acts on the inner side of the nozzle seat 41 to increase the oil pressure Fp, and the magnetic circuit 23 acting on the armature portion 1a becomes synergistically strong, and the attractive force Since Fs rises rapidly, the needle valve 1 is rapidly lifted (indicated by an arrow B in the figure).

The needle valve 1 is lifted until the armature portion 1 a comes into contact with the top surface of the pressure control chamber 7.
That is, in FIG. 2, the distance between the armature portion 1 a and the top surface of the pressure control chamber 7 serving as a stopper is the maximum lift h of the needle valve 1. When energization to the solenoid 5 is turned off after a predetermined time (t1), the suction force Fs acting on the control valve 6 and the needle valve 1 is suddenly reduced, and the valve body 61 of the control valve 6 closes the outlet throttle 9 to The pressure in the control chamber 7 rises again. When the force Fp + Fs acting on the valve opening side of the needle valve 1 falls below the force Fp ′ acting on the valve closing side, the needle valve 1 is closed.

  According to the present embodiment, the fuel injection forms a boot injection pattern in which the suction force acting on the needle valve 1 increases steeply as the lift starts and the needle valve lifts steeply to the maximum lift position (FIG. 3). At the bottom).

  Thus, in the present embodiment, in the configuration using the direct acting needle valve 1, the control valve 6 is provided to control the pressure in the pressure control chamber 7, and the solenoid 5 is connected to the control valve 6, the needle. By sharing the valve 1, the suction force of the solenoid 5 is effectively exhibited. The opening of the needle valve 1 is supported by the suction force of the solenoid 5 and the pressure drop in the pressure control chamber 7 due to the opening of the control valve 6, so that the direct-acting needle valve 1 does not increase in size. Can be opened and closed with good responsiveness. Further, by sharing the solenoid 5, it is possible to realize high-performance control by stabilizing the injection characteristics and improving the lift controllability in a space-saving and low-cost manner.

(Second Embodiment)
4 and 5 show a second embodiment of the present invention. 4 is an overall cross-sectional view showing a schematic configuration of the injector I, and FIG. 5 is a time chart showing an example of fuel injection control. In the present embodiment, as shown in FIG. 4, a solenoid 5 ′ (second solenoid) for the needle valve 1 is provided in addition to the solenoid 5 (first solenoid) for the control valve 6. The control valve 6 accommodates a substantially T-shaped valve body 64 in a valve chamber 63 provided close to the lower side of the solenoid 5, and opens and closes an outlet throttle 9 that opens to the bottom surface of the valve chamber 63. The valve chamber 63 is always in communication with the low-pressure channel 24, and a spring 62 accommodated in the in-cylinder space of the solenoid 5 biases the valve body 64 in the valve closing direction.

  The solenoid 5 ′ is disposed between the valve chamber 63 and the pressure control chamber 7, and a spring 12 is accommodated in the in-cylinder space of the solenoid 5 ′ communicating with the pressure control chamber 7 to close the needle valve 1. Is energized. The pressure control chamber 7 communicates with the outlet throttle 9 via the in-cylinder space of the solenoid 5 '. Other basic configurations of the injector I and the structure of each part are the same as those in the first embodiment, and a description thereof will be omitted.

  In this embodiment, solenoids 5 and 5 'for the control valve 6 and the needle valve 1 are provided independently, and the control valve 6 and the needle valve 1 are controlled independently. Specifically, first, the control valve 6 is opened by the solenoid 5, and after the pressure in the pressure control chamber 7 has sufficiently decreased, the solenoid 5 ′ is operated to open the needle valve 1. The suction force of 5 ′ can be used efficiently.

  The operation of the injector I of this embodiment will be described with reference to FIG. In FIG. 4, when the solenoid 5 is turned on from the state where the solenoids 5 and 5 ′ are not energized, the valve body 64 of the control valve 6 is driven to be sucked. When the outlet throttle 9 is opened by the lift of the control valve 6 and the pressure control chamber 7 and the low-pressure channel 24 communicate with each other, the fuel in the pressure control chamber 7 flows out through the outlet throttle 9 and the pressure gradually decreases.

  Unlike the first embodiment, at this time, the force acting on the needle valve 1 is only the downward action of the oil pressure (Pcr ′ × Ap) by the pressure control chamber 7 and the spring force (Fsp) of the spring 12. (Force Fp ′ = Pcr ′ × Ap + Fsp acting on the valve closing side), not acting in the valve opening direction. When the solenoid 5 'is energized when the pressure in the pressure control chamber 7 is reduced to a certain low pressure, a suction force (Fs) is generated, and the force Fs + Fp acting on the valve opening side becomes the force Fp acting on the valve closing side. If it exceeds, the needle valve 1 will start to lift.

  When the needle valve 1 is opened (maximum lift h), the energization of the solenoid 5 is turned off. As a result, the outlet throttle 9 is closed and the pressure (Pcr ′) in the pressure control chamber 7 rises again, but when the pressure control chamber 7 reaches a constant pressure (equivalent to the pressure Pcr in the oil-tight chamber), the valve closing side Opening can be maintained by setting so that the force Fp ′ acting on ≦ the force Fp + Fs acting on the valve opening side. Thus, the energization time (t2) to the solenoid 5 can be shortened by opening the control valve 6 only when the needle valve 1 is opened. When the solenoid 5 'is turned off after a predetermined time (t3) and the suction force Fs acting on the needle valve 1 is reduced, the needle valve 1 is closed by the force Fp' acting on the valve closing side.

  In the present embodiment, a plurality of solenoids 5 and 5 ′ are provided and the energization timing and the energization time are independently controlled, thereby enabling the same operation as in the first embodiment. In this configuration, since the control valve 6 is temporarily opened only when the needle valve 1 is opened, the amount of leakage from the outlet throttle 9 can be reduced, and the control valve 6 can be kept open. The load current (the part indicated by arrow A in FIG. 3) is also unnecessary. Further, since the solenoids 5 and 5 'need only generate a minimum suction force for opening the control valve 6 and the needle valve 1, respectively, the entire injector I can be made relatively small.

(Third embodiment)
6 to 11 show a third embodiment of the present invention. 6 is an overall cross-sectional view showing a schematic configuration of the injector I, FIG. 7 is an enlarged cross-sectional view showing the main part configuration, FIGS. 8, 9, and 10 are enlarged cross-sectional views of the main part showing the detailed operation of the injector, FIG. These are time charts showing an example of fuel injection control. As shown in FIG. 6, the present embodiment forms a magnetic circuit portion that passes in series through the magnetic body portions of the control valve 6 and the needle valve 1 in the same basic configuration as the first embodiment. The solenoid 5 is shared by the control valve 6 and the needle valve 1 as in the first embodiment.

  6 and 7, in the upper half of the body 2, a solenoid 5 is held around a cylindrical nonmagnetic body 51 that holds the outer periphery of the control valve 6 and held by a coil case 52. A pressure control chamber 7 is formed below the solenoid 5. The pressure control chamber 7 accommodates the armature portion 1 a of the needle valve 1. In the present embodiment, the top wall of the pressure control chamber 7 facing the armature portion 1a is configured by combining a magnetic material and a non-magnetic material, so that a magnetic circuit passing through the armature portion 1a can be easily formed. Specifically, a container-like valve body 91 that holds the lower end portion of the control valve 6 is provided, and the bottom thereof is the central portion of the top wall of the pressure control chamber 7. The body 53 is integrally provided as an outer peripheral portion of the top wall of the pressure control chamber 7.

  The valve body 91 made of a magnetic body has a cylindrical upper end joined to a lower end of the cylindrical non-magnetic body 51, and a bottom projecting into the pressure control chamber 7 and provided at the center of the upper surface of the armature unit 1a. It is located in the recessed portion 13. The upper end portion of the cylindrical nonmagnetic material 51 is joined to a cylindrical portion 25 that is formed to extend from the body 2 made of a magnetic material into the coil case 52. In the present embodiment, the control valve 6 slides using the cylindrical portion 25, the cylindrical nonmagnetic body 51, and the inner peripheral surface of the valve body 91 as a guide surface. In this way, the magnetic body portion is located on the outer periphery of the upper and lower end portions of the control valve 6, so that a magnetic circuit is easily formed.

  Further, an outlet throttle 9 is provided through the bottom center of the valve body 91 and is opened and closed by a valve body 61 of the control valve 6. The fuel that flows out from the outlet throttle 9 when the valve is opened flows out into the low-pressure channel 24 through the relief passage 65 that passes through the control valve 6 in the axial direction and communicates with the upper and lower end surfaces. A stepped portion serving as a stopper is formed on the body 2 wall above the control valve 6 to define the maximum lift h1 of the control valve 6.

  The annular non-magnetic body 53 has a flat plate shape with a predetermined thickness positioned in close contact with the bottom surface of the coil case 52, and is arranged so as to bridge between the valve body 91 and the outer body 2 thereof, and the solenoid 5 and the pressure control. The room 7 is shut off. In the annular recess formed between the annular non-magnetic body 53 and the valve body 91 and the body 2, an annular convex portion on the outer peripheral portion of the upper surface of the armature portion 1 a protrudes and faces the annular non-magnetic body 53. Yes. At this time, since the body 2 made of a magnetic material, the valve body 91, and the annular convex portion of the armature portion 1a are located close to each other, it is easy to form a magnetic circuit. A spring 12 is disposed between the flange 11 on the outer periphery of the armature portion 1a and the body 2 to urge the needle valve 1 downward.

  Here, in order to prevent direct contact between the annular non-magnetic body 53 and the armature part 1a, the maximum lift h2 of the needle valve 1 is set with the bottom surface of the valve body 91 facing the recessed part 13 of the armature part 1a as a stopper. Thereby, the cyclic | annular nonmagnetic body 53 can be protected and intensity | strength can be maintained, and the eddy current at the time of control valve 6 valve opening can be reduced. Further, the bottom surface of the valve body 91 that is in contact with the recessed portion 13 of the armature portion 1a when the needle valve 1 is fully lifted is substantially spherical, and both are in point contact, so that the pressure receiving area of the needle valve 1 is at the maximum lift position. There will be no major changes.

  In addition, an escape passage 14 communicating the inner space of the recessed portion 13 and the side surface above the flange 11 with the annular convex portion on the outer periphery of the armature portion 1a, and an escape passage 15 communicating the upper surface of the annular convex portion and the side surface above the flange 11 side. Is provided. Thereby, the fuel in the pressure control chamber 7 freely circulates in the annular recess formed above the armature portion 1a and the inner space of the recess portion 13 of the armature portion 1a, and does not hinder the lift. At this time, as described above, if the bottom surface of the valve body 91 serving as a stopper is substantially spherical, the maximum lift h2 can be easily set, and the escape passage 14 can be formed at a position not closed by the valve body 91. There is no hindrance to fuel flow.

  The operation of the injector I of this embodiment will be described with reference to FIGS. In FIG. 7, when the solenoid 5 is turned on from the state where the solenoid 5 is not energized, as shown in FIG. 8, the cylindrical portion 25 of the body 2, the control valve 6, the valve body 91, and the annular protrusion of the armature portion 1a. The magnetic circuit S3 passing through the body 2 is generated. In the configuration of the present embodiment, the outer peripheral portion of the top wall of the pressure control chamber 7 facing the armature portion 1a is formed by the annular nonmagnetic material 53, and the armature is provided between the valve body 91 and the body 2 serving as the central portion of the top wall. Since the annular convex part of the part 1a is arranged, the magnetic circuit S3 passing through the control valve 6 and the armature part 1a in series is formed. Further, the upper and lower end portions of the control valve 6 are in close contact with the body 2 and the valve body 91 made of a magnetic material, and the annular convex portions of the armature portion 1a are close to the valve body 91 and the body 2 with a slight gap. And the strong magnetic path which passes along the armature part 1a of the needle valve 1 in series will be formed.

  As shown in FIG. 11, the suction force Fs' generated simultaneously with the energization of the solenoid 5 increases in proportion to the current value, and quickly lifts the control valve 6 to the maximum lift h1 (see FIG. 7) position. When the valve body 61 of the control valve 6 opens the outlet throttle 9, the pressure control chamber 7 and the space in the valve body 91 communicate with each other through the recessed portion 13 of the armature portion 1a. As a result, when the fuel in the pressure control chamber 7 flows into the low-pressure channel 24 through the relief passage 65 of the control valve 6, the pressure Pcr 'in the pressure control chamber 7 gradually decreases.

  On the other hand, in the closed state, the attractive force Fs by the magnetic circuit S3 and the oil pressure Fp (= Pcr × (Ap−As)) of the oil reservoir 4 are acting on the armature portion 1a of the needle valve 1. In this embodiment, since the strong magnetic circuit S3 passing through the armature portion 1a is formed, the attraction force Fs rises quickly, and the combined force of the oil pressure and the attraction force (force Fp + Fs acting on the valve opening side) rises quickly. And become constant. Therefore, at a certain point in time before the pressure Pcr ′ of the pressure control chamber 7 decreases and becomes a constant pressure, the resultant force of the oil pressure by the pressure control chamber 7 and the spring force of the spring 12 (force Fp ′ acting on the valve closing side = When Pcr ′ × Ap + Fsp) is balanced and the pressure Pcr ′ in the pressure control chamber 7 further decreases, the force Fp + Fs acting on the valve opening side exceeds the force Fp ′ acting on the valve closing side (Fp ′ ≦ Fp + Fs). After that, the pressure Pcr 'in the pressure control chamber 7 gradually decreases until the inflow amount from the inlet throttle 8 and the outflow amount to the outlet throttle 9 are balanced to a predetermined pressure.

  As a result, as shown in FIG. 9, the solenoid 5 sucks and drives the armature portion 1a, and the needle valve 1 starts to lift. At this time, the lift of the needle valve 1 increases the oil pressure Fp (= Pcr × Ap) in the oil reservoir 4, so that the force Fp + Fs acting on the valve opening side easily exceeds the force Fp ′ acting on the valve closing side, The armature portion 1a can be quickly lifted to the maximum lift h2 (see FIG. 7) position that contacts the bottom of the valve body 91 that serves as a stopper.

  When the energization of the solenoid 5 is turned off after a predetermined time, the suction force Fs acting on the control valve 6 and the needle valve 1 is suddenly reduced, the valve body 61 of the control valve 6 closes the outlet throttle 9, and the pressure control chamber 7 The pressure rises again. When the force Fp + Fs acting on the needle valve 1 on the valve opening side falls below the force Fp ′ acting on the valve closing side, the needle valve 1 is closed.

  As described above, the magnetic circuit S3 that passes through the control valve 6 and the armature unit 1a in series is formed, so that a strong attractive force can be generated without dispersing the magnetism. Force can be generated efficiently. In addition, since a larger suction force can be generated by the proximity of the magnetic body portion forming the magnetic circuit S3, the suction force rises quickly, and the pressure of the needle valve 1 decreases as the pressure in the pressure control chamber 7 decreases. Lifting can be started quickly. As a result, the suction force can be increased without increasing the physique of the solenoid 5 and the current value, and the needle valve 1 can be controlled to open and close by direct action at a high injection pressure.

  In this embodiment, 1) only the central portion of the top wall of the pressure control chamber 7 is made of a magnetic material, and the outer peripheral portion is made of a non-magnetic material. 3) Integrate with the non-magnetic material on the outer peripheral portion of the top wall 3) Place the container-like top wall central portion in the pressure control chamber 7 4) Connect the upper end of the control valve 6 to the body 2 With the configuration of contacting with the magnetic circuit S3, the attractive force by the magnetic circuit S3 can be more effectively exhibited. However, it is not always necessary to provide all of these configurations, and the shape of each part may be different. If the magnetic circuit including the control valve 6 and the armature portion 1a of the needle valve 1 can be formed with as little space as possible, the same effect can be obtained.

  As described above, according to the present invention, in an injector that directly drives a needle valve by an electromagnetic drive unit, when the needle valve is opened, the pressure applied to the back of the needle valve is reduced, so that the needle valve can be easily opened and closed. Thus, fuel can be injected with high controllability at high injection pressure without increasing the suction force.

It is a whole sectional view showing a schematic structure of injector I in a 1st embodiment of the present invention. It is a principal part expanded sectional view of the injector in 1st Embodiment. It is a time chart for demonstrating the action | operation of the injector of 1st Embodiment. It is a whole sectional view showing a schematic structure of injector I in a 2nd embodiment of the present invention. It is a time chart for demonstrating the action | operation in the injector of 2nd Embodiment. It is a whole sectional view showing a schematic structure of injector I in a 3rd embodiment of the present invention. It is a principal part expanded sectional view of the injector in 3rd Embodiment. It is a principal part expanded sectional view which shows the valve opening state of the control valve in the injector of 3rd Embodiment. It is a principal part expanded sectional view which shows the valve opening state of the needle valve in the injector of 3rd Embodiment. It is a principal part expanded sectional view which shows the valve closing state of the control valve in the injector I of 3rd Embodiment. It is a time chart for demonstrating the action | operation in the injector of 3rd Embodiment.

Explanation of symbols

I Injector S1, S2, S3 Magnetic circuit 1 Needle valve 1a Armature portion 11 Flange 12 Spring 13 Recessed portion 14, 15 Relief passage 2 Body 21 High pressure piping 22 Low pressure piping 23 High pressure passage 24 Low pressure passage 25 Tube portion 3 Injection hole 31 Suck part 4 Oil reservoir chamber 41 Nozzle sheet 5 Solenoid (first solenoid)
5 'Solenoid (second solenoid)
51 Cylindrical non-magnetic material 52 Coil case 53 Annular non-magnetic material 6 Control valve 61 Valve body 62 Spring 63 Valve chamber 64 Valve body 65 Relief passage 7 Pressure control chamber 8 Inlet throttle 9 Outlet throttle 91 Valve body

Claims (6)

An injector for injecting high-pressure fuel supplied from a high-pressure fuel supply path by sucking and driving a needle valve accommodated in a rod-shaped body by an electromagnetic drive unit, opening and closing a nozzle hole provided at the body tip,
An armature portion provided integrally with the base end portion of the needle valve is accommodated in a pressure control chamber communicating with the high pressure fuel supply path, and a back pressure is applied to the needle valve.
The electromagnetic drive unit is provided with a control valve that opens and closes between the pressure control chamber and the low pressure fuel outflow passage.
The needle drive valve is lifted by a suction force acting on the needle valve in a state where the pressure of the pressure control chamber is lowered by opening the control valve by the electromagnetic drive unit. Injector.   The injector according to claim 1, wherein the electromagnetic drive unit includes one solenoid, and the needle valve is lifted by a suction force of the solenoid that sucks and drives the control valve.   The electromagnetic drive unit includes two solenoids, the control valve is opened by the suction force of the first solenoid, and the pressure control chamber communicates with the low-pressure fuel outflow passage and becomes a predetermined pressure or less. 2. The injector according to claim 1, wherein the needle valve is lifted by the suction force of the second solenoid.   The injector according to claim 3, wherein the electromagnetic drive unit stops energizing the first solenoid after energizing the second solenoid.   3. The injector according to claim 2, wherein in the electromagnetic drive unit, a magnetic circuit that applies an attractive force to the control valve and the needle valve passes in series through the magnetic body of the control valve and the needle valve.   The needle valve is accommodated in the lower half of the body, the electromagnetic drive unit is accommodated in the upper half, the control valve is coaxially disposed above the needle valve, and the outer periphery of the control valve is made of a magnetic material. Is held by a cylindrical portion made of a non-magnetic material, and the central portion of the top wall of the pressure control chamber facing the control valve is made of a magnetic material, and the pressure located between the solenoid and the armature 6. The injector according to claim 5, wherein the outer peripheral portion of the top wall of the control chamber is made of a nonmagnetic material.

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