Patent Publication Number: US-6213098-B1

Title: Fuel injection device

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of Japanese Patent Applications No. H.11-245639 filed on Aug. 31, 1999, No. H.11-308951 filed on Oct. 29, 1999 and No. 2000-36678 filed on Feb. 15, 2000, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fuel injection device in which fuel may be stepwise injected. 
     2. Description of Related Art 
     Conventionally, in a fuel supply system in which fuel is supplied from a high pressure supply pump to an injector that is a fuel injection device, a technology that a needle lift is varied by a value of fuel pressure to change its injection characteristic has been proposed. Injection rate, atomization density and distribution behavior of fuel affect largely on fuel ignitability, formation of NOx, black smoke, HC and the like and combustion efficiency. 
     For example, well known is a nozzle with two-stage valve opening pressure that has two springs for biasing a needle with a predetermined needle lift interval. According to this technology, the needle lifts due to pressure of fuel delivered by a fuel injection pump. However, a value of pressure of fuel delivered to the fuel injection device from the fuel injection pump becomes variable according to engine operations. Therefore, it is difficult to always realize an optimum injection rate demanded by the engine over an entire range of engine operations. 
     To cope with this problem, an injector  230 , as disclosed in U.S. Pat. No. 5,694,903 and shown in FIG. 42, is known. The injector  230  is provided with a control chamber  260  by which fuel pressure is applied to a needle  231  in a direction of closing an injection hole. A lift of the needle  231  is controlled by making a force acting in a direction of opening the injection hole due to fuel pressure transmitted to a fuel accumulating space  232  larger or smaller than a sum of forces receiving in a direction of closing the injection hole due to the fuel pressure of the control chamber  260  and biasing force of a spring  237 . Even if the fuel pressure is varied according to the engine operations, regulating pressure of the control chamber  260  accurately controls an opening and closing timing by the needle  231 . 
     Further, a lift of a pilot valve stem  270  is controlled with two steps by biasing forces of two springs  290  for urging the pilot valve stem  270  in a direction of closing the control chamber  260  and an attracting force of a coil  274 . As a result, it is intended that the needle  231  is stepwise lifted to secure a predetermined fuel injection rate. 
     However, the conventional fuel injection device has a drawback that, even if the stem  270  is stepwise lifted, the needle is not always stepwise lifted simultaneously with the stem  270 , since the needle  231  is lifted when a value of the fuel pressure of the fuel accumulating space  232  exceeds a sum value of pressure of the control chamber  260  and biasing force of the spring  237 . Further, if the electromagnetic attracting force of the coil  274  is varied due to, for example, a change of temperature, a lifting characteristic of the stem  270  such as an opening area characteristic of the stem  270  is forced to change. Furthermore, due to a characteristic change of fuel such as viscosity, the pressure of the control chamber  260  is changed unstably. Accordingly, a lifting characteristic of the needle  231  is also changed so that the fuel injection rate may become unstable. Moreover, since a lifting control amount of the stem  270  is very small, it is difficult to secure a uniform quality in each of the injectors  230  so that an accurate and stable injection control may not be realized. 
     In the conventional fuel injection devices, though the injection rate may be variably controlled so far, it is impossible to realize a variable control of fuel atomization event such as atomization angle and droplets reaching distance. 
     Inadequate control of the atomization event causes to harm fuel consumption and an output so that NOx, black smoke, HC and the like may be more formed. 
     Further, as shown in JP-A-10-54323, well known is a fuel injection valve in which control valves are arranged at an inlet portion through which high pressure is introduced to the control chamber and at an outlet portion through which high pressure is released from the control chamber, respectively. With the plurality of control valves, the lift of the needle is stepwise controlled to obtain the stable lift control, while the leak amount can be reduced, since respective opening and closing controls of the inlet and outlet of the control chamber can be independently controlled. 
     However, the injection valve mentioned above still has a drawback that the valve becomes larger and is expensive since pluralities of electromagnetic valves are necessary. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a fuel injection device in which fuel injection events may be accurately controlled according to engine conditions and the formation of NOx, black smoke and HC may be limited to improve the fuel consumption and the output. 
     To achieve the object, the injection device is composed of a valve member slidably movable in a valve body to open and close an injection hole, a high pressure fuel passage for generating a basic fuel pressure force to urge the valve member in a direction of opening the injection hole, fuel passages communicated with the high pressure fuel passage and to be communicated with a low pressure fuel conduit, control valve means disposed in the fuel passages, biasing means for generating a biasing force to urge the valve member in a direction of closing the injection hole, and a plurality of control chambers disposed in the fuel passages. 
     The respective plurality of control chambers are communicated with the high pressure passage when the control valve means is not actuated and respective fuel pressure in the plurality of control chambers are used as chamber fuel pressure forces to urge the valve member in a direction of closing the injection hole, and the respective control chambers are communicated one after another at different timings to the low pressure conduit to reduce fuel pressure therein when the control valve means is actuated. 
     With the device mentioned above, the valve member may be stepwise lifted to achieve variable fuel injection rate by controlling one after another at different timings the chamber fuel pressure force from selected any one of the plurality of control chambers that is applied to the valve member in order to change a force balance with the basic fuel pressure force and the biasing force that are then applied to the valve member. 
     According to the fuel injection device mentioned above, even if fuel pressure to be introduced into the device is varied according to engine operating conditions, a timing of the valve member for opening and closing the injection hole may be accurately controlled. 
     It is preferable for the accurate stepwise lifting of the valve member that the biasing means comprises a first biasing element for generating first biasing force to urge the valve member in a direction of closing the injection hole irrelevantly to a lifting amount of the valve member and a second biasing element for generating second biasing force to urge the valve member in a direction of closing the injection hole after the valve member has established a predetermined lifting amount. 
     Preferably, the valve member comprises a needle to be seated on the valve seat and a transmitting element provided on an opposite side to the injection hole with respect to the needle for transmitting the biasing force and the chamber fuel pressure forces of the plurality of control chambers to the needle. The transmitting element may be an element integrated into one body having a plurality of cross sectional areas, whose largeness are different from each other, for receiving respective fuel pressure from the plurality of control chambers, or an element separated into a plurality of bodies having respective cross sectional areas, whose largeness are different from each other, for receiving fuel pressure respectively from the plurality of control chambers. 
     Further, the transmitting element preferably has separated areas for receiving fuel pressure from the respective plurality of control chambers. If more than two of the control chambers and the corresponding biasing means are provided, the valve member may move with more than two stage stepwise lifting. 
     The respective plurality of control chambers are formed on an axis same as that of the transmitting element so that a small fuel injection device may be realized. 
     Furthermore, it is preferable in view of compactness of the device that the biasing means is located in one or the plurality of control chambers. 
     An area of the valve member which receives fuel pressure from selected any of the plurality of control chambers for producing the chamber fuel pressure force is larger than an area of the valve member which receives fuel pressure from the high pressure passage for generating the main fuel pressure force, when the valve member is seated on the valve seat, and the area of the valve member which receives fuel pressure from selected any of the plurality of control chambers for producing the chamber fuel pressure force becomes smaller than the area of the valve member which receives fuel pressure from the high pressure passage for generating the main fuel pressure force, when the valve member lifts in a direction away from the valve seat. Accordingly, as a speed at which the valve member is seated on the valve seat is limited, a valve closing shock may be eased. 
     Preferably, the control valve means has a plurality of moving members which are operative to open and close fuel passages on a side of the low pressure conduit with respect to the respective plurality of control chambers. As the respective control chambers may be independently and stepwise controlled so that the valve member is lifted stepwise. 
     Further, it is preferred that the plurality of moving members are provided on a common axis and have control valve springs for biasing the respective plurality of moving members in a direction of closing the fuel passages to be communicated to the low pressure conduit, the plurality of moving members being operative at respective different timings to open the fuel passages on a side of the low pressure conduit with respect to the plurality of control chambers against the biasing forces of the control valve springs. With this construction, the injection device becomes compact and the respective pressure of the control chambers may be highly accurately controlled. 
     In a case that the plurality of the control chambers comprise first and second control chambers for producing the chamber fuel pressure forces to urge the valve member in a direction of closing the injection hole, the plurality of the control valve means comprise first and second moving members and first and second control valve springs, and the first moving member is slidably and reciprocatingly held in the second moving member in such a manner that, at first, the first moving member comes in contact with the second moving member in a predetermined lifting stroke after the first moving member moves to open the fuel passage on a side of the low pressure conduit with respect to the first control chamber and, then, the first moving member together with the second moving member further moves so that the fuel passage on a side of the low pressure conduit with respect to the second control chamber may be opened by the second moving member. With this construction, the injection valve becomes compact because one driving source serves to lift the respective moving members. 
     The valve member may establish a first lifting amount in a low to middle speed range or a low to middle load range as engine operating conditions, and a second lifting amount larger than the first lifting amount in a high speed range or a high load range as engine operating conditions. According to the engine operating conditions, optimum fuel injection rate may be selected. 
     Furthermore, the valve member may change stepwise a lifting amount from the first lifting amount to the second lifting amount within a fuel injection period when the engine operating conditions show a change from the low speed range to the high speed range or a change from the low load range to the high load range. As an optimum injection rate may be realized within a fuel injection period, Generation of NOx, HC and black carbon may be limited. 
     Moreover, the valve member may be moved to inject fuel with optimum numbers of injections in a cycle of engine and in an optimum lifting state of the valve member and for an optimum injection period in each injection, when engine operating conditions are changed from one to another or the valve member may be moved to inject fuel with optimum numbers of injections in a cycle of engine and in an optimum lifting state of the valve member during whole ranges of engine operating conditions. These control result in reducing generation of NOx, HC and Black carbon. 
     Preferably, the plurality of control chambers comprise first and second control chambers and the second control chamber is communicated with the high pressure passage. The valve member comprises a needle to be seated on the valve seat and first and second pistons for forming the first and second control chambers on an opposite side to the injection hole with respect to the needle for transmitting the chamber fuel pressure forces from the first and second control chambers to the needle. The control valve means has a valve chamber formed in the fuel passages, a control valve movable in the valve chamber and an electrically controlled device for driving stepwise the control valve. The valve chamber has a first opening communicated with the fuel passage leading to the first control chamber, a second opening communicated with the fuel passage leading to the second control passage and a low pressure opening to be communicated to the low pressure conduit. 
     With this construction, a fuel communication between the first and low pressure openings and a fuel communication between the second and low pressure openings are sequentially controlled by the stepwise moving of the control valve so that the chamber fuel pressure forces of the first and second control chambers may be changed. As the first and second pistons work with the valve member for controlling stepwise the valve member, variable injection rate may be secured. 
     The control valve closes the low pressure opening when the electrically controlled device is not actuated. High pressure fuel of the high pressure passage is introduced via the second opening to the valve chamber and, then, high pressure fuel is transmitted via the first opening to the first control chamber. The high pressure passage communicated with the second control chamber is communicated to the valve chamber in which the low pressure opening is closed. Therefore, the first and second pistons are urged in a direction of closing the injection valve by high pressure fuel of the first and second control chambers. The needle, which is also urged in a direction of closing the injection hole by the biasing means, is seated on the valve seat. 
     Next, the control valve opens the low pressure opening when the electrically controlled device is actuated to drive the control vale during a first lifting stroke so that the first and second control chambers may be communicated to the low pressure conduit. Accordingly, fuel pressure of the first and second control chamber is changed from a high pressure state to a low pressure state to drive the first and second pistons as follows. 
     The first piston lifts and comes in contact with the second piston (first lifting amount) and the first piston further lifts along with the second piston (second lifting amount). The needle lifts by an amount corresponding to first and second lifting amounts of the first and second pistons so that the needle moves apart from the valve seat to inject fuel from the injection hole. 
     Then, the control valve closes the second control chamber when the electrically controlled device is further actuated to drive the control valve during a second lifting stroke so that the communication of the second control chamber to the low pressure conduit may be interrupted, while the communication of the first control chamber via the valve chamber to the low pressure conduit may be maintained. As high pressure of the second control chamber is maintained for urging the second piston in a direction of closing the injection hole, the first piston comes in contact with the second piston and stops at that position so that the needle moves by the first lifting amount to inject fuel from the injection hole. 
     In a case that, when the control valve lifts the second lifting stroke and the first piston moves by the first lifting amount, the communication between the high pressure passage and the low pressure conduit is interrupted as the second opening is closed. Therefore, the fuel pump effectively works without circulating excessive high pressure fuel so that fuel consumption of engine may be improved. 
     Further, it is preferable that the biasing means comprises a first biasing element for generating first biasing force to urge the valve member in a direction of closing the injection hole irrelevantly to a lifting amount of the valve member and a second biasing element for generating second biasing force to urge the valve member in a direction of closing the injection hole after the valve member has established a predetermined lifting amount. The first biasing element serves to prevent the needle apart from the valve seat when the first and second control chambers are communicated to the low pressure conduit and urging forces of the pistons to the needle in a direction of closing the injection hole are reduced. The second biasing element serves to prevent the second piston from upwardly moving due to an inertia force based on lifting the first piston when the first piston comes in contact with the second piston. Therefore, a stable injection may be secured. 
     If the low pressure opening is closed when the control valve is at a position in the valve chamber most near the electrically control device, fuel leakage through a clearance necessary for sliding the control valve in the electrically control device may be reduced since the clearance is located under low fuel pressure circumstances. 
     It is preferable that the fuel passage between the second control chamber and the second opening is provided with a first throttle for regulating fuel flow and with the fuel passage for communicating the second control chamber to the high pressure passage on a side of the second control chamber relative to the first throttle. The construction has a merit that one of the throttles may be eliminated, compared with the construction in which high pressure is introduced from the high pressure passage via the second control chamber to the first control chamber. The one elimination of the throttles results in supplying fuel smoothly and rapidly to the first control chamber, thus resulting in increasing the downward speed of the needle for closing the injection hole so that the response ability of the valve member may improve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings: 
     FIG. 1 is a cross sectional view of an injector according to a first embodiment of the present invention; 
     FIG. 2 is a partly enlarged view of the injector shown in FIG. 1; 
     FIG. 3 is a partly enlarged another view of the injector shown in FIG. 1; 
     FIG. 4 is a part view of the injector shown in FIG. 1 for explaining a first lift stroke of a control valve. 
     FIG. 5 is a part view of the injector shown in FIG. 1 for explaining a second lift stroke of a control valve. 
     FIG. 6 is a time chart showing a stepwise lifting; 
     FIG. 7A is an enlarged view of a nozzle portion with respect to the injector shown in FIG. 1; 
     FIG. 7B is a cross sectional view taken along a line VIIB—VIIB of FIG. 7A at a low lift; 
     FIG. 7C is a cross sectional view of FIG. 7B at a maximum lift; 
     FIG. 8 is an enlarged view of a nozzle portion with respect to the injector shown in FIG. 1 at the maximum lift; 
     FIG. 9 is a characteristic chart showing a relationship among a flow speed, atomization angle and lift amount. 
     FIG. 10A is a chart showing a relationship between engine revolution and engine load. 
     FIG. 10B is a chart showing a relationship between engine revolution and injection pressure. 
     FIG. 10C is a chart showing a relationship between engine revolution and injection time. 
     FIG. 11A is a cross sectional view of an injector according to a second embodiment of the present invention; 
     FIG. 11B is a partly enlarged view of the injector shown in FIG. 11A; 
     FIG. 12 is a cross sectional view of an injector according to a third embodiment of the present invention; 
     FIG. 13 is a cross sectional view of an injector according to a fourth embodiment of the present invention; 
     FIG. 14 is a cross sectional view of an injector according to a fifth embodiment of the present invention; 
     FIG. 15 is a cross sectional view of an electromagnetic valve of an injector according to a sixth embodiment of the present invention; 
     FIG. 16 is a cross sectional view of a modified electromagnetic valve of the injector according to the sixth embodiment of the present invention; 
     FIG. 17 is a cross sectional view of an electromagnetic valve of an injector according to a seventh embodiment of the present invention; 
     FIG. 18A is a cross sectional view of an electromagnetic valve of an injector according to a eighth embodiment of the present invention; 
     FIG. 18B is a cross sectional part view taken along a line XVIIIB—XVIIIB of FIG. 18A; 
     FIG. 19 is a cross sectional view of an injector according to a ninth embodiment of the present invention; 
     FIG. 20 is a cross sectional view of an injector according to a tenth embodiment of the present invention; 
     FIG. 21 is a cross sectional view of an injector according to an eleventh embodiment of the present invention; 
     FIG. 22 is a time chart showing a stepwise lift according to the eleventh embodiment; 
     FIG. 23 is across sectional view of an injector according to an twelfth embodiment of the present invention; 
     FIG. 24 is a partly enlarged view of the injector shown in FIG. 23; 
     FIG. 25 is a time chart showing a stepwise lift according to the twelfth embodiment; 
     FIG. 26 is a schematic cross sectional view showing an injector according to a thirteenth embodiment; 
     FIG. 27 is a schematic cross sectional view showing a modification of the injector according to the thirteenth embodiment; 
     FIG. 28A is a timing chart showing a valve closing speed of a needle according to the thirteenth embodiment; 
     FIG. 28B is a timing chart showing a valve closing speed of a needle according to a modification of the thirteenth embodiment; 
     FIG. 28C is a timing chart showing a valve closing speed of a needle according to the thirteenth embodiment combined with the modification of the thirteenth embodiment; 
     FIG. 29A is a cross sectional view of injector according to a fourteenth embodiment; 
     FIG. 29B is a cross sectional view rotated by 90° with respect to the injector of FIG. 29A; 
     FIG. 30 is a part view showing a second lift of a valve element of the injector according to the fourteenth embodiment; 
     FIG. 31 is a part view showing a first lift of the valve element of the injector according to the fourteenth embodiment; 
     FIG. 32 is a time chart showing a stepwise lift according to the fourteenth embodiment; 
     FIG. 33 is a view of a control valve according to a modification of the fourteenth embodiment; 
     FIG. 34 is a cross sectional view of an electromagnetic valve of the injector according to a fifteenth embodiment; 
     FIG. 35 is a cross sectional view of an injector according to a sixteenth embodiment; 
     FIG. 36 is a cross sectional part view of an injector according to a seventeenth embodiment; 
     FIG. 37 is a cross sectional part view of an injector according to an eighteenth embodiment; 
     FIG. 38 is a cross sectional part view of an injector according to a nineteenth embodiment; 
     FIG. 39 is a cross sectional part view of an injector according to a modification of the nineteenth embodiment; 
     FIG. 40 is a cross sectional part view of an injector according to a twentieth embodiment; 
     FIG. 41 is a cross sectional view of a throttle of an injector according to a modification of the twentieth embodiment; and 
     FIG. 42 is a cross sectional view of a conventional injector as a prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     (First Embodiment) 
     FIG. 1 shows an injector  1  as a fuel injection device according to a first embodiment of the present invention. The injector  1  is installed in an engine head (not shown) of an engine for directly injecting fuel in each cylinder of the engine. High pressure fuel discharged from a fuel injection pump is accumulated to a predetermined pressure in a pressure accumulating chamber of a pressure accumulating pipe (not shown) and is sullied to the injector  1 . A discharge pressure of the fuel injection pump is adjusted according to engine revolution, load, intake fuel pressure, intake air volume and coolant temperature. 
     In the injector  1 , a valve body  12  is fastened via a tip packing  13  to a housing  11  by a retaining nut  14 . A valve element  20  is composed of, from a side of an injection hole  12   b  in order, a needle  21 , a rod  23 , a control piston  24  and a control piston  25 . The rod  23  and control pistons  24  and  25  constitute a transmitting element. 
     The needle  21  is held by the valve body  12  so as to make a reciprocating movement therein. The needle  21  is urged to a valve seat  12   a  formed in the valve body  12  via the control pistons  25  and  24  and the rod  23  by a first spring  15 , as first biasing means. The first spring  15  is housed in a second control chamber  65  on a same axis as the control piston  25 . An initial preload of the first spring  15  is Fs 1  and a spring constant thereof is K 1 . A second spring  16 , as second biasing means, is fitted around a circumference of the rod  23  in the housing  11  on a same axis as the rod  23  and presses a spring seat  17  against the tip packing  13 . An initial preload of the second spring  16  is Fs 2  and a spring constant thereof is K 2 . As shown in FIG. 2, when the spring seat  17  is seated on the tip packing  13 , a clearance between a lower end surface  17   a  and s shoulder portion  22  of the needle  21  has a length h 1 , which constitutes a first lifting amount. Further, when the spring seat  17  is seated on the tip packing  13 , the lower end surface  17   a  of the spring seat  17  protrudes out of a lower end surface  13   a  by a length h 2 , which constitutes a second lifting amount. Therefore, a maximum lifting amount of the needle  21  is a length h 1 +h 2 . 
     As shown in FIG. 1, an electromagnetic valve  30  is fastened to an upper part of the housing  11  by a nut  31 . The electromagnetic valve is composed of an armature  32 , a body  33 , a plate  34 , a coil  35 , a first control valve  40 , a second control valve  43 , the first spring  42  and the second spring  44 . The first and second control valves  40  and  43  are movable members. 
     The second control valve  43  may be seated on a valve seat  33   a  formed on the body  33  by a biasing force of the second spring. The second control valve  43  is formed in a cylindrical shape and has a through hole penetrating in an axial direction. The first control valve  40  is held by an inner circumferential wall of the second control valve  43  so as to make a reciprocal movement therein. The first and second control valves are arranged on a same axis. The first control valve  40  may be seated on the plate  34  by a biasing force of the first spring  42 . The core  41  located above the first control valve  40  is attracted to an end surface  32   a  of the armature  32  against the biasing force of the first spring  42  by a magnetic attracting force exerted on energizing the coil  35 . As shown in FIG. 4, the first lifting amount H 1  corresponds to a moving distance of the first control valve  40 , which is upward lifted until the first control valve  40  comes in contact with an end  43   a  of the second control valve  43 . When a larger current is supplied to the coil  35 , the force attracting the core  41  of the first control valve  40  becomes stronger so that both the first and second control valves  40  and  43  may be upward lifted against the sum of biasing forces of the first and second springs  42  and  44  and stops when the second control valve  43  comes in contact with a stopper  32   b  of the armature  32 . The second lifting amount H 2  corresponds to a moving distance of the second control valve  43  after the first control valve  40  comes in contact with the second control valve  43  and until the second control valve  43  comes in contact with the stopper  32   b  of the armature  32 . The maximum lifting amount of the first control valve  40  is h 1 +h 2 . 
     As shown in FIG. 3, an inlet throttle  61  and an outlet throttle  62  are respectively communicated with the first control chamber  60 , as a pressure chamber. A passage area of the outlet throttle  62  is larger than that of the inlet throttle  61 . The outlet throttle  62  is a fuel passage to be communicated with a low pressure side. The inlet throttle  61  is formed in a liner  26 , which is press fitted or closely fitted to the housing  11 , and is communicated with a fuel passage  51 . High pressure fuel is supplied via a fuel in-flow passage  50 , the fuel passage  51  and the inlet throttle  61  to the first control chamber  60 . The outlet throttle  62  is formed in the plate  34  put between the body and the housing  11  and is communicated with a fuel chamber  63 . 
     An inlet throttle  66  and an outlet throttle  67  are respectively communicated with the second control chamber  65 , as another pressure chamber. A passage area of the outlet throttle  67  is larger than that of the inlet throttle  66 . The inlet throttle  66  is communicated with the fuel passage  51  and high pressure fuel is supplied via the fuel in-flow passage  50 , the fuel passage  51  and the inlet throttle  66  to the second control chamber  65 . The outlet throttle  67  is communicated with a fuel passage  68 . The outlet throttle  67 , the fuel passage  68  and fuel passages  69  and  70  constitute fuel passages to be communicated with a low pressure side. 
     When the first control valve  40  opens the outlet throttle  62 , the high pressure fuel in the first control chamber  60  is evacuated via the outlet throttle  62 , the fuel chamber  63  on a low pressure side, fuel passages  64 ,  57   a  and  56   a  and a fuel out-flow passage  58  to a fuel tank  3 . The fuel passage  57  is formed around the body  33  to communicated with the fuel passage  64  and is communicated via the fuel passage  56   a  provided in the plate  34  to the fuel passage  56 . The fuel passage  56 , which is opened to a circumference of the rod in the housing  11 , is used to evacuate low pressure fuel in the housing  11  to the fuel tank  3 . 
     When the second control valve  43  is apart from the valve seat  33   a  of the body  33  and opens the fuel passage  70 , high pressure fuel in the second control chamber  65  is evacuated via the outlet throttle  67 , the fuel passages  68 ,  69  and  70 , the fuel chamber  63 , the fuel passages  64 ,  57   a,    56   a,  and the fuel out-flow passages  58  to the fuel tank  3 . A fuel passage  57 , which is communicated with the fuel passage  57   a  formed in the body  33 , is opened to an inside of the electromagnetic valve  30  where the second spring  44  is housed and is used to evacuate low pressure fuel in the inside of the electromagnetic valve  30  via the fuel passages  57   a  and  56   a  to the fuel tank  3 . 
     The control piston  24  is closely fitted to the housing  11 . The control piston  25 , which is located on an opposite side of the injection hole relative to the control piston  24 , is closely fitted to the liner  26  and faces to the first control chamber  60 . A lower part of the control piston  24  is in contact with the rod  23 . One end of the first spring  15  is in contact with the liner  26  and the other end thereof is retained by the control piston  25 . The control pistons  24  and  25 , which are provided separately, may be integrated as one body. Further, the control piston  24  may be integrated with the rod  23 . 
     A sum of an area Ap 1 , on which the control pistons  24  and  25  receive fuel pressure from the first control chamber  60 , and an area Ap 2 , on which the control pistons  24  and  25  receive fuel pressure from the second control chamber  65 , is larger than a cross sectional area of a guide portion of the needle  21  which slides the valve body  12 , that is, a cross sectional area Ag of a bore of the valve body  12  in which the needle  21  is housed. High pressure fuel supplied from the pressure accumulating pipe (not shown) is transmitted via the fuel in-flow passage  50  formed in the housing  11 , the fuel passage  51 , a fuel passage formed in the tip packing  13 , a fuel passage  53  formed in the nozzle body  12 , the fuel accumulating space  54  and a fuel passage around the needle  21  to a valve portion  2  formed by the needle  21  and the valve seat  12   a.    
     Next, detail construction of the valve portion  2  is described. As shown in FIG. 7A, a contacting portion  21   a,  which is provided at a leading end of the needle  21  may be seated on the valve seat  12   a  of the valve body  12 . The valve portion  2  is composed of the contacting portion  21   a,  a circular force generating portion  210 , a swirl chamber  219  and the injection hole  12   b.  The circular force generating portion  210  is constituted by conical faces  211 ,  212  and  213  formed at an outer circumference of the needle  21 , a cylindrical face  214  and a plurality of oblique grooves  215 . The conical face  211  is formed with a conical angle that is slightly smaller than or same as that of a seat face  220 . 
     The circular force generation portion  210  is not limited to the construction mentioned above for securing functions and effects mentioned below, but may be a construction such that a conical face is formed in the valve body  12  such as the seat face  220 , a conical face is also formed at the outer circumference of the needle  21  such as the conical face  211  so as to face to the conical face on a valve body side, and oblique grooves are provided in one of the conical faces on the needle side and on the valve body side. Both of the conical faces may be replaced with both of spherical surfaces. 
     The swirl chamber  219  is constituted by the seat face  220  of the valve body  12  and both of a conical face  213  and a cylindrical face  216 , which are positioned at the needle  21  on a downstream of the circulation force generating portion  210 . The swirl chamber  219  is not limited in the shape mentioned above and the cylindrical face  216  may be replaced with a conical face, a composite cylindrical and conical surface or a spherical surface. The contacting portion  21   a  of the needle  21  may be seated on the valve seat  12   a  by a biasing force of the first spring in a direction of closing the injection hole. On the other hand, the contacting portion  21   a  of the needle  21  receives a force due to the fuel pressure in the fuel passage  55  in a direction apart from the valve seat  12   a,  that is, in a direction of opening the injection hole. A flow passage at a downstream of the contacting portion  21   a  is provided with the seat face  220  and conical faces  217  and  218  of the needle  21 . A conical angle of the conical face  217  is larger than that of the seat face  220  and a conical angle of the conical face  218  is larger than that of the conical face  217 . The valve body  12  is provided with a conical face  221  that is continuously changed from the seat face  220  to constitute the flow passage communicated to the injection hole  12   b.  The conical faces  217  and  218  may be one surface having a same conical angle. Further, the seat face  220  and the conical face  221  may be one conical face having a same angle as the seat face  220  or a curved surface such as an arc. 
     Next, an operation of the injector  1  is described. Fuel discharged from the fuel injection pump (not shown) is delivered to the accumulating pipe (not shown). The high pressure fuel, pressure of which is accumulated to a predetermined value by the accumulating chamber in the accumulating pipe, is supplied to the injector  1 . Current for driving the control valve, a value of which is controlled by an engine control apparatus (ECU) according to engine operations, is supplied to the coil  35  of the electromagnetic valve  30 . The electromagnetic attracting force of the coil exerted by the current supply attracts the first control valve  40  against the biasing force of the first spring  42 . Then, the outlet throttle  62  is opened so that the first control chamber  60  is communicated via the outlet throttle  62  with the fuel chamber  63  on a side of low pressure. As the passage area of the outlet throttle  62  is larger than that of the inlet throttle  61 , the volume of the out-flow fuel is larger than that of the in-flow fuel so that the fuel pressure Pc 1  of the first control chamber  60  begins to decrease. The pressure decreasing speed may be adequately set by adjusting a difference of the passage areas between the outlet and inlet throttles  62  and  61  and a volume of the first control chamber. 
     When the pressure in the first control chamber  60  is decreased and the sum of the pre-loaded force of the first spring  15  and the force received from the fuel pressure of the first and second control chambers  60  and  65 , both of which act in a direction of closing the injection hole, becomes lower than a force of moving upwardly the needle  21 , the needle  21  begins to open the injection hole. If the electromagnetic attracting force exerted by holding current IH 1  supplied to the coil  35  is smaller than the sum of biasing forces of the first and second springs  42  and  44 , the first control valve  40  stops at a position showing the first lifting amount H 1 , as shown in FIG.  1 . 
     Next, force acting on the needle  21  is described. 
     (1) When the lifting amount h of the needle  21  is less than the first lifting amount h 1  (h&gt;h 1 ): 
     {circle around (1)} At a valve closing by needle (h=0); 
     A valve closing force Fc 1  is a sum of a force Fct acting on the valve element  20  in a direction of closing the injection hole due to the fuel pressure Pct of the first and second control chambers  60  and  65  and an initial pre-loaded force Fs 1  of the first spring  15 . That is, Fc 1 =Fct+Fs 1 =Pct×Ap+Fs 1  and, further, Pct×Ap=Pc 1 ×Ap 1 +Pc 2 ×Ap 2  where Pc 1  is pressure of the first control chamber  60 , Pc 2  is pressure of the second control chamber  65 , Ap 1  is an area of the valve element  20  receiving fuel pressure from the first control chamber  60  in a direction of closing the injection hole, and Ap 2  is an area of the valve element  20  receiving fuel pressure from the second control chamber  65  in a direction of closing the injection valve. There is a relation, Ap=Ap 1 +Ap 2 . 
     A valve opening force Fo is a force Fd acting on the needle  21  due to fuel pressure in a direction of opening the injection hole, that is, Fo=Fd=Pd (Ag−As) where Pd is fuel pressure in the fuel passage  55  and As is an area of the valve seat  12   a  on which the needle  21  is seated. 
     A force F applied to the needle  21  is shown by the following formula (1). 
     
       
           F=Fo−Fc   1 = Pd ( Ag−As )− Pct×Ap−Fs   1   (1) 
       
     
     {circle around (2)} At a valve opening by needle (o&lt;h&lt;h 1 ); 
     When fuel pressure of the first control chamber  60  is decreased and the needle valve  21  is moved apart from the valve seat  12   a,  a spring force Fs becomes Fs=Fs 1 +K 1 ×h by adding a force corresponding to a contraction h of the first spring  15 . Accordingly, the valve closing force Fc 1  is Fc 1 =Fct+Fs=Fct+Fs 1 +K 1 ×h and the valve opening force Fo=Fd=Pd×Ag. The force F applied to the needle  21  is shown by the following formula (2). 
     
       
           F=Fo−Fc   1 = Pd×Ag−Fct−Fs   1 − K   1 × h   (2) 
       
     
     The area of the valve element  20  receiving fuel pressure, which is equal to the area Ap receiving fuel pressure from the first and second control chambers  60  and  65  minus the area Ap 1  receiving fuel pressure from the first control chamber  60  where the fuel pressure is reduced, that is, the area Ap 2  receiving fuel pressure from the second chamber  65 , is smaller than Ag. 
     (2) When the lifting amount h of the needle  21  is equal to or more than the first lifting amount h 1  (h 1 ≦h): The spring force Fs is Fs=K 1 ×h+Fs 1 +K 2 (h−h 1 )+Fs 2  by adding the initial pre-loaded force Fs 2  and a force due to the contraction of the second spring  16 . The valve closing force Fc 1  is Fc 1 =Fct+Fs=Pct×Ap+K 1 ×h+Fs 1 +K 2 (h−h 1 )+Fs 2 . The valve opening force Fo is Fo=Fd=Pd×Ag. The force F applied to the needle  21  is shown by the following formula (3). 
     
       
           F=Fo−Fc   1 = Pd×Ag−Pct×Ap−K   1 × h−Fs   1 − K   2 ( h−h   2 )− Fs   2   (3) 
       
     
     Next, forces acting on the first and second control valves  40  and  43  are described. 
     (1) At a valve closing time when the lifting amount H of the first control valve is zero (H=0): 
     A valve closing force Fvcl acting on the first valve  40  is only an initial pre-load Fvs 1  of the first spring  42 , that is, Fvc 1 =Fvs 1 . Valve opening force acting on the first control valve  40  is a valve opening force Fvo 1  which the first control valve  40  receives from the fuel pressure Pc 1  of the first control chamber  60 , that is, Fvo 1 =Ao 1 ×Pc 1  where Ao 1  is an opening area of the outlet throttle  62 . A force Fv 1  applied to the first control valve  40  is shown by the following formula (4). 
     
       
           Fv   1 = Fvo   1 − Fvc   1 = Ao   1 × Pc   1 − Fvs   1   (4) 
       
     
     A valve closing force Fvc 2  acting on the second valve  43  is an initial pre-load Fvs 2  of the second spring  44 , that is, Fvc 1 =Fvs 1 . A valve opening force Fvo 2  acting on the second control valve  43  is a valve opening force which the second control valve  43  receives from the fuel pressure Pc 2  of the second control chamber  65 , that is, Fvo 2 =Ao 2 ×Pc 2  where Ao 2  is an area on which the second control valve seated on the valve seat  33   a  receives the fuel pressure of the second control chamber  65 . The force Fv 2  applied to the second control valve  43  is shown by the following formula (5). 
     
       
           Fv   2 = Fvo   2 − Fvc   2 = Ao   2 × Pc   2 − Fvs   2   (5) 
       
     
     At H=0, the first and second control valves  40  and  43  do not receive a force from each other. 
     (2) When only the first control valve  40  is lifted ( 0 &lt;H&lt;H 1 ): 
     A magnetic attracting force Fm 1  exerted by the holding current IH 1  supplied to the coil  35 , which is applied to the first control valve  40 , caused the first control valve  40  to lift from the plate  34 . As the initial pre-load Fvs 1  and the force due to the contraction of the first spring  42  is applied to the control valve  40  as the valve closing force, the valve closing force Fvc 1  acting on the first control valve  40  is Fvc 1 =Fvs 1 +K 1 ×H. The valve opening force Fvo 1  thereof is the magnetic attracting force Fm 1  and a force that the first control valve  40  receives from the fuel pressure Pv 1  of the fuel chamber  63  on an area counterbalanced by its upper and lower pressure receiving areas. At H&gt;0, the fuel pressure Pv 1  of the first control chamber  60  affects via the outlet throttle  62  on the fuel pressure Pv 1  of the fuel chamber  63 , unless the fuel pressure Pv 1  is low. However, the fuel chamber  63  is opened via the fuel passages  64 ,  57   a  and  56   a  and the fuel out-flow passage  58  to the fuel tank  3  so that the fuel pressure of the fuel chamber  63  is almost equal to atmospheric pressure, that is, negligible pressure. A sum of the valve opening force is Fvo 1 =Fm 1 +Avo 1 ×Pv 1 . The force Fv 1  applied to the first control valve  40  is shown by the following formula (6). 
     
       
           Fv   1 = Fvo   1 − Fvc   1 = Fm   1 + Avo   1 × Pv   1 − Fvs   1 − K   1 × H   (6) 
       
     
     At this time, the force applied to the second control valve  43  is same to that shown in the formula (5). 
     (3) When the first and second control valves  40  and  43  are lifted (H 1 ≦H): 
     A magnetic attracting force Fm 2  exerted by the second holding current IH 2  supplied to the coil  35  is applied to the first control valve  40 . A valve closing force applied to the first control valve  40  is Fvs 1 +K 1 ×H by the spring force of the first spring  42 . In addition to that, the spring force Fvs 2 +K 2  (H−H 1 ) of the second spring  44  acting on the second control valve  43  is applied. Therefore, the valve closing force Fvc 1  applied to the first control valve  40  is Fvc 1 =Fvs 1 +K 1 ×H+Fvs 2 +K 2 ×(H−H 1 ). The valve opening force Fvo 1  applied to the first control valve  40  is Fvo 1 =Fm 2 +Avo 1 ×Pv 1 . The force Fv 1  applied to the first control valve  40 , if neglect a force receiving from the second control valve  43 , is shown by the following formula (7). 
     
       
           Fv   1 = Fvo   1 − Fvc   1 = Fm   2 + Avo   1 × Pv   1 − Fvs   1 − K   1 × H   (7) 
       
     
     Next, as the second control valve  43  is lifted, the fuel pressure of the fuel passage  70  reduces from Pc 1  and becomes Pv 2  near atmospheric pressure, same as that of the fuel chamber  63 , that is, Pv 2 ≈Pv 1 . A valve opening force Fvo 2  applied to the second control valve  43  is Fvo 2 =Avo 2 ×Pv 2  where Avo 2  is a pressure receiving area of the second control valve  43  which receive pressure in a valve opening direction from the fuel chamber  63  and the fuel passage  70 . A valve closing force Fvc 2  applied to the second control valve  43  is Fvc 2 =Fvs 2 +K 2 ×(H−H 1 ). The force Fv 2  applied to the second control valve  43 , if neglect a force receiving from the first control valve  40 , is shown by the following formula (8). 
     
       
           Fv   2 = Fvo   2 − Fvc   2 = Avo   2 × Pv   2 − Fvs   2 − K   2 ×(H−H 1 )  (8) 
       
     
     A sum Fv of the force applied to the first and second control valves  40  and  43  is shown by the following formula (9). 
     
       
           Fv=Fm   2 + Avo   1 × Pv   1 − Fvs   1 − K   1 × H+Avo   2 × Pv   2 − Fvs   2 − K   2 ×(H−H 1 )  (9) 
       
     
     When the magnetic attracting force exerted by the driving current applied to the coil  35  causes the first control valve  40  to move against the spring force of the first spring  42  and establishes the first lifting amount H 1  as shown in FIG. 4, the fuel pressure Pc 1  of the first control chamber  60  is reduced. Accordingly, the pressure Pd from the accumulating pipe, if exceeds the sum of the fuel pressure Pc 1  and the initial pre-load of the first spring  15 , causes the needle  21  to move upwardly against the first spring  15  so as to open the injection hole. This is a case that a condition F≧0 is satisfied in the formula (1). Therefore, the needle  21  is lifted by the first lifting amount h 1 . 
     After moving the first lifting amount h 1 , the needle  21  receives the initial pre-load Fs 2  of the second spring  16  so that the needle  21  stops lifting and keeps the first lifting amount h 1 , as shown in a needle lift diagram (A) in FIG.  6 . Even if the fuel pressure of the first control chamber is reduced, the needle  21  keeps the first lifting amount h 1 , as far as F≧0 in the formula (2) and F&lt;0 in the formula (3) are satisfied. 
     Further, when higher current is supplied to the coil  35  of the electromagnetic valve  30  and the electromagnetic attracting force is increased, the second control valve  43  is moved together with the first control valve  40  against the biasing forces of the first and second springs  42  and  44  to establish a lifting state (H 1 +H 2 ) as shown in FIG.  6 . Accordingly, when the fuel pressure of the second control chamber  65  is reduced and F≧0 in the formula (3) is satisfied, the needle  21  is lifted to exceed the first lifting amount h 1  so that the needle  21  may be further lifted by the second lifting amount h 2  in addition to the first lifting amount h 1 . The total needle lifting amount becomes h 1 +h 2  that is a maximum lifting state as shown in (b) of (B) or (C) in FIG.  6 . 
     According to the fuel pressure reduction of the second control chamber  65 , force acting on the needle  21  in a valve opening direction is further increased. However, as the shoulder portion  22  of the needle  21  comes in contact with the lower end surface of the tip packing  13 , further lifting of the needle  21  is stopped. The force in a direction of opening the injection hole is received by the tip packing  13 . After a lapse of a predetermined driving pulse time, the supply of the driving current to the coil  35  is stopped and the second control valve  43  is seated on the valve seat  33   a  so that the fuel passage  70  may be closed. Then, the fuel pressure of the second control chamber  65  begins to increase due to high pressure fuel flown from the inlet throttle  66 . Further, when the outlet throttle  62  is closed by the first control valve  40  seated on the plate  34 , the fuel pressure of the first control chamber  60  increases due to high pressure fuel flown from the inlet throttle  61 . 
     As the force of moving downwardly the control pistons  24  and  25  is increased, the needle  21  begins to move downward in a direction of closing the injection hole via the rod  23 . When the needle  21  has moved downward by the second lifting amount h 2 , the needle  21  does not receives the biasing force of the second spring  16  and only the fuel pressure of the first and second control chambers  60  and  65  and the initial pre-load Fs 1  of the first spring  15  urge the valve element  20  in a direction of closing the injection hole. As the valve closing force acting on the needle  21  is reduced, the needle  21  is slowly seated on the valve seat  12   a  so that seating impact and noise may be reduced. 
     As mentioned above, the fuel pressure of the first and second control chambers  60  and  65  are controlled by the first and second control valves  40  and  43 , which are regulated by the current supplied to the electromagnetic valve  30 , and, further, controlled by the preset passage areas of two pairs of the throttles  61  and  62  and the throttles  66  and  67 . The needle  21  is stepwise lifted by controlling the force receiving from the fuel pressure in a direction of opening or closing the injection hole relative to the biasing forces of the first and second springs  15  and  16 . At the valve opening time, various lifting characteristics such as a lifting of only the first lifting amount h 1 , lifting of the first and second lifting amounts h 1 +h 2  or stepwise lifting with a longer time interval of the first lifting amount h 1  before starting the second lifting amount h 2 . Further, at the valve closing time, it is possible to eliminate or shorten the time interval of h 1 . As a result, fuel injection amount at an initial stage may be reduced so that nitrogen oxide and combustion noise may be limited. Further, the fuel injection rate at injection last stage may be closed with a shorter time so that the formation of black smoke may be reduced. 
     The following described is an operation of the valve portion  2  when the lifting of the needle  21  is stepwise controlled. 
     When the needle  21  lifted by h 1 , a clearance between the conical face  211  of the needle  21  and the seat face  220  is very small as shown in FIG.  7 B. At this time, as shown in FIG. 8, flow speed of fuel flowing in the oblique groove  215  is Vn and flow speed of fuel flowing in the clearance between the conical face  211  and the seat face  220  is Wb. As shown in FIG. 9A, the speed Vn may be resolved into a speed component Un in a circumferential direction and a speed component Wb in an axial direction. A speed ratio of Vn to Wb is decided by a ratio of one passage area to the other passage area and shows a change according to a lifting of the needle  21  as shown in FIG.  9 B. 
     Since the flow area of the oblique groove  215  is constant irrelevant to the lifting of the needle, the speed Vn in the oblique groove  215  may be increased, as the fuel amount is increased according to a largeness of an opening area between the contacting portion  21   a  and the valve seat  12   a.  If the opening area between the contacting portion  21   a  and the valve seat  12   a  at a vicinity of the first lifting amount h 1  is set to be equal to the passage area of the oblique groove  215 , Vn shows a maximum speed at the first lifting amount h 1 . 
     Though Wn is increased in proportion to the needle lifting, a value of Wn is smaller than that of Vn and Wn is more slowly increased, compared with Vn, as far as the needle lifting amount is within a range substantially from several microns to several tenth millimeters. As a result, the ratio of Vn to Wb is maximum at near the first lifting amount h 1 . At this time, the atomization angle may be decided by a ratio of the speed component in a circumferential direction to the speed component in an axial direction at an outlet of the injection hole, which becomes equal to a ratio of the speed component Un in a circumferential direction to the speed component W=Wn+Wb in an axial direction with respect to fuel flown into the swirl chamber  219  in view of a momentum preservation law and a free swirl law. That is, fuel is injected with a atomization angle α decisive by a formula of tan(α/2)=Un/(Wn+Wb). 
     When the fuel pressure of the first control chamber  60  is further reduced, the needle  21  is lifted against the biasing forces of the first and second springs  15  and  16  to obtain the maximum lifting amount (h 1 +h 2 ). At this state, as the area between the contacting portion  21   a  and the valve seat  12   a  is enlarged and the fuel speed Wb is increased, the speed Vn in the oblique groove  215  is disturbed and decreased by Wb. Consequently, the atomization angle α is decreased as shown in FIG.  9 C. 
     According to the first embodiment, as a diameter of the swirl chamber  219  is relatively small and a volume of the swirl chamber  219  is reduced, a time delay is limited before the circulation force to the fuel is established. Further, as the swirl chamber  219  is provided right above the contacting portion  21   a,  a change of the atomization angle is immediately followed to the lifting amount. As the atomization by the swirl injection serves to split fuel into tiny particles, fuel with more tiny articles may be injected with lower injection pressure, compared with the other hole nozzle type. 
     A method of controlling the injector of the first embodiment according to engine operations is described. 
     As shown in FIG. 10, at a region of low and middle speed and low and middle load, basically, the lifting of the needle  21  is controlled to maintain a low lifting state of the first lifting amount h 1  so that fuel is supplied to a combustion chamber with a low injection rate and a short droplets reaching distance. At a region of high speed and high load, the needle is lifted by h 1 +h 2  to realize a high injection rate and a high droplets reaching distance. 
     The injection pressure shown in FIG.  10 B and the injection timing shown in FIG. 10C are controlled in accordance with a map based on injection amount. Adjustments due to temperature (air, coolant and fuel), an intake pressure and soon are added to the map. In an engine to be normally operated, a first step lifting driving region that the lifting amount is h 1  and a second step lifting driving region that the lifting amount is h 1 +h 2  are changed as shown by a solid line in FIG.  10 A. 
     However, in an engine to be installed in a vehicle having a transient driving region, which is presumed to be, for example, a broken line region as shown in FIG. 10A, it becomes necessary to change the lifting amount by a special control in order to prevent a stepwise output change of the engine when the engine conditions fall within the broken line range mentioned above. For example, as shown in (C) in FIG. 6, if the current supplied to the electromagnetic valve  30  is controlled to realize the stepwise lifting during the injection period, the stepwise output change may be prevented. A ratio of the first step lifting length to the second step lifting length may be changed according engine operating conditions fallen within the broken line range shown in FIG.  10 A. Further, a plurality of injections may be set during a cycle of the engine. For example, when the engine operating condition is being changed from the low load to the high load, a plurality of first step injections are made with only the first lifting amount h 1  and, then, a number of second step injections with the first and second lifting amount, h 1 +h 2 , may be gradually increased from zero to a certain numbers or respective injection periods among the plurality of injections may be separately controlled. Furthermore, it is possible to combine a lifting mode shown in (C) of FIG. 6 with a plurality of combinations of (A) and (B) of FIG.  6 . Moreover, when the driving conditions are fluctuating back and forth within the broken line region shown in FIG. 10A, it is possible to have a hysteresis for injection control. 
     According to the first embodiment mentioned above, a variable atomization angle technology necessary for realizing future combustion concept may be provided with a low cost and with a low injection pressure by the construction that the needle is stably controlled with two stages and the circular force acting on the fuel flow may be changed at the valve portion  2  by the needle lifting. Further, inlet and outlet edges of the oblique groove  215  are rounded with lager radius on their oblique sides, respectively, that is, on an in-flow inner side at the inlet and on a swirl flow downstream side at the outlet. As a result, fuel flow loss may be limited and the fuel flow separation does not occur so that a generation of cavity may be prevented. In other words, unnecessary pressure increase in the injection system may be prevented, resulting in improving a machinery efficiency and reliability of the nozzle. 
     Further, when the valve element  20  starts the valve closing from the maximum lifting amount (h 1 +h 2 ), the valve closing speed is high due to the sum of biasing forces of the first and second springs  15  and  16 . However, at a region of less than the first lifting amount h 1 , a valve closing speed of the needle just before being seated on the valve seat becomes slow so that the valve closing hammer shock may be eased. 
     Furthermore, in a state that the valve element  20  is away from the valve seat  12   a,  a pressure receiving area on which the valve element  20  receives fuel pressure in a direction of opening the injection hole is larger than a pressure receiving area on which the valve element  20  receives fuel pressure from the both control chambers in a direction of closing the injection hole minus a pressure receiving area on which the valve element  20  receives fuel pressure from the control chamber whose fuel outlet is opened. Accordingly, a speed of the needle  21  for being seated on the valve seat  12   a  is reduced to ease the valve closing hammer shock, thus resulting in improving reliability. 
     Moreover, at a light load operation in which only first stage lifting injection is performed, the fuel injection rate becomes low so as to stably control a very small amount of injection. 
     Further, the contacting portion  21   a  of the needle  21  may be adjusted not to off set its center due to pressure balancing effect in the swirl chamber  219  so that the needle  21  and the valve body  12  may be always on the same axis so as to prevent variations of atomization. 
     (Second Embodiment) 
     A second embodiment of the present invention is described with reference to FIGS. 11A and 11B. With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. 
     Instead of the first embodiment in which fuel circular velocity direction becomes variable based on the distance between the circular force generating portion  210  and the seat face  220 , according to the second embodiment, a plurality of first and second injection holes  81  and  82 , which are provided in a valve body  80 , are selectively opened and closed based on a lifting amount of a needle  83  so as to change the injection rate and the state of the atomization. That is, the first and second injection holes constitute variable injection means. 
     A fuel passage  84  is formed inside the needle  83 . The fuel passage  83  is communicated via the fuel accumulating space  54  to the fuel passage  51  provided in the valve body  80 . A contacting portion  83   a  of the needle  83  is urged to a valve seat  80   a  provided in the valve body  80  by the biasing force of the first spring  15  (not shown in FIGS.  11 A and  11 B). The first and second injection holes  81  and  82 , which constitute first and second groups of injection holes, respectively, are opened to an outer circumference of the valve body  80  at a plurality portions. There is a distance Lh between the respective lower side portions of the first and second injection holes  81  and  82 . The distance Lh is larger than the first lifting amount h 1  of the needle  83  but smaller than the maximum lifting amount (h 1 +h 2 ) thereof. 
     When the needle  83  begins to lift due to the drive of the electromagnetic valve and the contacting portion  83   a  moves away from the valve seat  80   a,  high pressure fuel begins to be injected from the first injection hole  81 . When the needle  83  continues to lift and stops at the first lifting amount h 1 , only the first injection hole  81  is opened. Then, when the needle  83  further lifts and the lifting amount exceeds Lh, fuel is injected from the second injection hole  82 , too. At the maximum lifting amount (h 1 +h 2 ) of the needle  83 , the first and second injection holes  81  and  82  are fully opened to secure maximum injection rate. (h 1 +h 2 ) is set to be larger than (Lh+diameter of the second injection hole  82 ). 
     Instead of the wide-angle conical shaped single atomization of the first embodiment, a plurality of atomization, each of which is a narrow angle atomization in each of the injection holes, are formed to constitute a conical shaped atomization as a whole according to the second embodiment. Each conical atomization angle of the first group of injection holes may differ from that of the second group of injection holes. Further, the injection rate may be changed by controlling stepwise with two stages the lifting amount of the needle  83  and, further, may be adjusted by changing the respective diameters of the first and second injection holes  81  and  82 . 
     (Third Embodiment) 
     An injector according to a third embodiment of the present invention is described with reference to FIG.  12 . With respect to components and construction of an injector  4  substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. The construction of the electromagnetic valve  30  is schematically shown. According to the third embodiment, the first spring  15  is located beneath the control piston  24  for biasing the rod  23 , instead of being disposed in the second control chamber  65  according to the first embodiment. A basic operation of the third embodiment is same to that of the first embodiment. As the volume of the second control chamber  65  of the third embodiment may be smaller, a changing responsiveness of fuel pressure Pc 2  in the second chamber  65  becomes fast so that valve opening and closing responsiveness of the needle  21  may be improved. Further, as fuel in-flow and out-flow amount necessary for changing pressure may be reduced and the discharge amount of the fuel injection pump may be limited, engine output may be improved because of necessity of less driving torque of the fuel injection pump. 
     (Fourth Embodiment) 
     A fourth embodiment of the present invention is described with reference to FIG.  13 . With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the first embodiment is that the first spring  15  is arranged inside the second spring  16  and the biasing force of the first spring  15  is given via a pressure pin  85  to the needle  21 . As an upper end of the needle has a flat surface without a prolonged portion thereof, a shape of the needle  21  becomes simple. Further, according to the fourth embodiment, only the first lifting amount h 1  is defined in such a manner that the needle  21  comes in contact with a spring seat  86  of the second spring  16  and the second lifting amount h 2  is not defined. 
     The construction mentioned above serves to shorten a length of the rod  23  and to reduce the mass of the valve element  20 . Further, as the second lifting amount depend on a balance between the forces acting on the needle in a direction of opening the injection hole and in a direction of closing the injection hole, adjusting processes on manufacturing the valve element  20  may be skipped to save its manufacturing cost. 
     (Fifth Embodiment) 
     A fifth embodiment of the present invention is described with reference to FIG.  14 . With respect to components and construction of an injector  5  substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. According to the fifth embodiment, the construction of the electromagnetic valve becomes more compact by using a two position-two way electromagnetic valve  90  instead of the three position-three way electromagnetic valve  30  of the first embodiment. Consequently, the first and second control valves  40  and  43  are integrated into one body and one of the first and second springs  42  and  44  is omitted, though they are not shown in the drawing. The electromagnetic valve  90  is operative to open and close only the outlet throttle  62  of the first control chamber  60 . The second control chamber  65  is not provided with the outlet throttle for out-flowing fuel. Therefore, pressure of the second control chamber  65  is not controlled and is always applied from pressure accumulating space. Further, the tip packing  13  of the first embodiment is omitted and, instead, a spring seat  91  of the second spring  16  is in contact with an end surface of the valve body  12 . The second lifting amount h 2  is not defined, as similar to the fourth embodiment. 
     In the construction mentioned above, the pressure for stating a second stage lifting of the needle  21  can not be controlled and the needle  21  automatically starts the second stage lifting with a predetermined constant pressure. The construction and control of the injector become simple, thus resulting in low cost and compact injector. 
     (Sixth Embodiment) 
     A sixth embodiment of the present invention is described with reference to FIG.  15 . With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. 
     A liner  100  is put between the plate  34  and a housing  105 . The liner  100  is provided with a flange portion  101  and a cylindrical portion  102 . The flange portion  101  is provided with a communication passage  101   a,  which communicates the second control chamber  65  and the outlet throttle  67 , and the inlet throttle  61 . 
     The control piston  110  is composed of a column portion  111  in a center and a cylindrical portion  112  outside the column portion  111 . The cylindrical portion  112  has a cylindrical groove formed around an outer circumference of the column portion  111  and a larger diameter portion  112   a  extending radically and outwardly. The cylindrical portion  102  of the liner  100  is slidably fitted to the column portion  111  of the control piston  110 . 
     As the control piston  110  has the larger diameter portion  112   a,  an area receiving fuel pressure of the second control chamber  65  is larger so as to increase fuel pressure necessary for the second stage lifting to a maximum injection pressure. 
     (Modification) 
     A modification of a shape of the liner  100  according to the sixth embodiment is shown in FIG. 16. A liner  120 , which is formed in a cylindrical shape, is urged toward the plate  34  by the first spring  15  so that the first and second control chambers  60  and  65  are hydraulically sealed. 
     (Seventh Embodiment) 
     A seventh embodiment of the present invention is described with reference to FIG.  17 . With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the first embodiment is that the second spring  44  is arranged on a side of a second control valve  123  relative to a spacer  121 . With this construction, a length of a first control valve becomes shorter so that the electromagnetic valve may become compact. 
     (Eighth Embodiment) 
     An eighth embodiment of the present invention is described with reference to FIG.  18 . With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. Differences from the first embodiment are that a core  131  of a first control valve  130  is formed in a flat plate shape instead of the plunger shape and the first spring  42  is arranged above the armature  32 . The core  131  is fitted to a projection  130   a  formed in the first control valve  130 . As the core  131  is of the flat plate shape, electromagnetic attracting force acting on the first control valve  130  increases. Further, as an adjustment of the first spring  42  is easy, a lift start timing of the second control valve  132  may be accurately set. 
     (Ninth Embodiment) 
     A ninth embodiment of the present invention is described with reference to FIG.  19 . With respect to components and construction substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. Differences from the first embodiment are that a first control valve  140  locating outside lifts at first and, then, a second control valve  145  locating inside lifts. The second control valve and the second spring  44  are housed inside the first control valve  140 . With this construction, the first lifting amount H 1  is defined in such a manner that a step portion  141  inside the first control valve  140  comes in contact with a stop portion  146  of the second control valve  145 . The maximum lifting amount (H 1 +H 2 ) is defined in such a manner that a core  142  of the first control valve  140  comes in contact with en end surface  150   a  of an armature  150 . The first and second control chambers  60  and  65  are positioned in reverse each other in response to the positional relationship between the first and second control valves  140  and  145 . 
     (Tenth Embodiment) 
     A tenth embodiment of the present invention is described with reference to FIG.  20 . With respect to components and construction substantially same to those of the ninth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. Differences from the ninth embodiment are that both of the first and second springs  42  and  44  for biasing the first and control chambers  140  and  145 , respectively, are positioned on a side of the core  142 . According to the ninth and tenth embodiment, the control valve construction including the core  142  is simple and may be manufactured at lower cost. As construction flexibility for the first and second control chambers  60  and  65  increases, an injector to be easily installed in the engine may be manufactured. 
     (Eleventh Embodiment) 
     An eleventh embodiment of the present invention is described with reference to FIG.  21 . With respect to components and construction of an injector  6  substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. The construction of the electromagnetic valve  30  is schematically shown. A valve position  30   a  of the electromagnetic valve  30  shown in FIG. 21 represents a state that driving current is not supplied to the coil  35  in the first embodiment. A valve position  30   b  represents a state that only the first control valve lifts and a valve position  3   c  represents a state that the first and second control valves lift. 
     A control piston  27  is positioned on an opposite side of the needle with respect to the control piston  24 . In a state that the needle  21  is seated on the valve seat  12   a,  the control piston  27  is in no contact with the control piston  24 . The first control chamber  60  is provided between the control pistons  24  and  27 . The second control chamber  65  is provided on an opposite side of the first control chamber relative to the control piston  27 . As explained later in detail, when the needle  21  lifts so as to exceed the lifting amount h 1 , fuel pressure of the second control chamber  65  acts against the control piston  24  and the needle  21  in a direction of closing the injection hole and the second control chamber  65  constitutes biasing means as well as the pressure chamber. By controlling the pressure of the first control chamber  60 , the injection hole  12   b  may be opened and closed. By controlling the pressure of the second control chamber  65 , the lifting amount of the needle  21  is selected to h 1  or (h 1 +h 2 ). 
     Next, operation of the injector  6  is described. 
     In a state that the needle  21  is seated on the valve seat  12   a  as shown in FIG. 21, when the coil  35  of the electromagnetic valve  30  is energized by ECU (not shown) with driving current according to engine operating conditions as shown in FIG.  22 (A) and the valve position  30   b  of the electromagnetic valve  30  is selected, the outlet throttle  62  is opened and fuel pressure Pc 1  of the first control chamber  60  begins to reduce. When the pressure of the first control chamber  60  reduces to an extent that a sum of the biasing force of the first spring  15  and a force receiving from fuel pressure of the first control chamber  60  in a direction of closing the injection hole becomes lower than a force urging upwardly the needle  21 , the needle  21  and the control piston  24  begins to lift to spray fuel from the injection hole  12   b.  When the needle  21  and the control piston  24  lifts by the first lifting amount h 1 , the control piston  24  runs against the control piston  27 . As the fuel pressure of the second control chamber  65  acts in a direction of moving the needle  21  to close the injection hole, if a fuel outlet is closed and the fuel pressure of the second control chamber is high, the needle  21  stops in a state that the control piston  24  comes in contact with the control piston  27 . 
     In a state shown in FIG. 21, when the coil  35  of the electromagnetic valve  30  is energized with driving current according to engine operating conditions as shown in FIG.  22 (B) and the valve position  30   c  of the electromagnetic valve  30  is selected, the outlet throttles  62  and  67  are opened and fuel pressure Pc 1  and Pc 2  of the first and second control chambers  60  and  65  begin to reduce. When the needle  21  and the control piston  24  lift and the control piston  24  runs against the control piston  27 , the second control chamber  65  is in a state of low fuel pressure. Therefore, the needle  21  and the control piston  24  lift to exceed the first lifting amount h 1  and, after lifting (h 1 +h 2 ), further lifting of the needle  21  is stopped by a lower end surface  13   a  of the tip packing  13 . 
     If the current to be supplied to the coil  35  is increased during an injection period, the lifting amount may be increased from h 1  to (h 1 +h 2 ) as shown in FIG.  22 (C). On the contrary, if the current to be supplied to the coil  35  is reduced during an injection period, the lifting amount may be decreased from (h 1 +h 2 ) to h 1 . 
     When the current supply to the coil  35  is interrupted after a lapse of a predetermined time at a state shown in FIG.  22 (C), the outlet throttles  62  and  67  are closed so that fuel pressure of the first and second control chambers  60  and  65  increase. As a result, control pistons  24  and  27  are pushed downwardly in a direction of closing the injection hole and the needle  21  is seated on the valve seat  12   a  to finish the fuel injection. 
     Next, force acting on the needle  21  is described. 
     (1) When the lifting amount h of the needle  21  is less than the first lifting amount h 1  (h&lt;h 1 ): 
     {circle around (1)} At a valve closing by needle (h=0); 
     A valve closing force Fc 1  is a sum of a force Fct 1  acting on the valve element  20  in a direction of closing the injection hole due to the fuel pressure Pc 1  of the first control chamber  60  and an initial pre-loaded force Fs 1  of the first spring  15 . That is, Fc 1 =Fct 1 +Fs 1 =Pc 1 ×Ap 1 +Fs 1  where Pc 1  is pressure of the first control chamber  60 , and Ap 1  is an area of the valve element  20  receiving fuel pressure from the first control chamber  60  in a direction of closing the injection hole. 
     A valve opening force Fo is a force Fd acting on the needle  21  due to fuel pressure in a direction of opening the injection hole, that is, Fo=Fd=Pd (Ag−As) where Pd is fuel pressure in the fuel passage  55 , Ag is a cross sectional hole area of the valve body  12  and As is an area of the valve seat  12   a  on which the needle  21  is seated. 
     A force F applied to the needle  21  is shown by the following formula (10). 
     
       
           F=Fo−Fc   1 = Pd ( Ag−As )− Pc   1 × Ap   1 − Fs   1   (10) 
       
     
     {circle around (2)} At a valve opening by needle (o&lt;h&lt;h 1 ); 
     When fuel pressure of the first control chamber  60  is decreased and the needle valve  21  is moved apart from the valve seat  12   a,  a spring force Fs becomes Fs=Fs 1 +K 1 ×h by adding a force corresponding to a contraction h of the first spring  15 . Accordingly, the valve closing force Fc 1  is Fc 1 =Fct 1 +Fs=Fct 1 +Fs 1 +K 1 ×h and the valve opening force Fo=Fd=Pd×Ag. The force F applied to the needle  21  is shown by the following formula (11). 
     
       
           F=Fo−Fc   1 = Pd×Ag−Pc   1 × Ap   1 − Fs   1 − K   1 × h   (11) 
       
     
     (2) When the lifting amount h of the needle  21  is equal to or more than the first lifting amount h 1  (h 1 ≦h): As the control piston  24  is in contact with the control piston  27 , a force Fct 2  acting on the control piston  27  in a direction of closing the injection hole due to fuel pressure Pc 2  of the second control chamber  65  is also applied to the needle  21 . Fct=Fct 1 +Fct 2 . Therefore, the valve closing force Fc 1  is Fc 1 =Fct+Fs=Fct 1 +Fct 2 +Fs 1 +K 1 ×h=Pc 1 ×Ap 1 +Pc 2 ×Ap 2 +Fs 1 +K 1 ×h. Ap 2  is an area of the control piston  27  receiving fuel pressure in a direction of closing the injection hole from the second control chamber  65 . The valve opening force Fo is Fo=Fd=Pd×Ag. The force F applied to the needle  21  is shown by the following formula (12). 
     
       
           F=Fo−Fc   1 = Pd×Ag−Pc   1 × Ap   1 − Pc   2 × Ap   2 − Fs   1 − K   1 × h   (12) 
       
     
     When the needle lifting amount is h 1 , Pc 2  is almost same pressure as Pd. When the needle lifting amount is (h 1 +h 2 ), pc 2  is pressure lower than Pd. 
     According to the eleventh embodiment, the first control chamber  60  is formed between the control pistons  24  and  27  and the control piston  24  does not come in contact with the control piston  27  until lifting of the needle  21  becomes h 1 . The needle lifting amount may be freely changed by controlling driving current to be supplied to the coil  35  irrespectively to the value of the injection pressure. Consequently, any injection rate may be adequately realized. 
     (Twelfth Embodiment) 
     A twelfth embodiment of the present invention is described with reference to FIGS. 23 and 24. With respect to components and construction of an injector  7  substantially same to those of the first embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. According to the twelfth embodiment, a piezo element is used as a driving force of the control valve. 
     A valve holder  160 , another valve holder  162  and a valve seat member  165  are put between the valve body  12  and a housing  167 . A retaining nut  14  fastens the valve body  12  and the housing  167 . Similarly to the eleventh embodiment, the control piston  27  is positioned on an opposite side of the needle with respect to the control piston  24 . In a state that the needle  21  is seated on the valve seat  12   a,  the control piston  27  is retained on a shoulder portion  161  of the valve holder  160  and is in no contact with the control piston  24 . The first control chamber  60  is provided between the control pistons  24  and  27 . The second control chamber  65  is provided on an opposite side of the first control chamber relative to the control piston  27 . 
     The control valve  170  is slidably and reciprocatingly housed in the valve holder  162 . A spring  173  urges the control valve  170  toward a valve seat  166  of valve seat element  165 . A piezo element  180  is connected in circuit with a pin  182  embedded in a connector  181 . When a current voltage is applied to the piezo element  180 , the piezo element  180  is expanded downward in FIG.  23 . As the applied voltage is higher, an expanded length of the piezo element  180  becomes longer. 
     An end of a hydraulic piston  183  is in contact with the piezo element  180  and the other end thereof is in contact with a plate spring  184 . So, the hydraulic piston  183  is urged toward the piezo element  180 . A hydraulic piston  188  is urged toward the hydraulic piston  183  by a spring  188 . A rod  187  of the hydraulic piston  186  is in contact with the control valve  170 . 
     As shown in FIG. 24, high pressure fuel is applied to a fuel space  190  formed around the control valve  170  via the fuel passage  51  and a throttle  195  from the common rail irreverently to a position of the control valve  170 . In a state that a contacting portion  171  of the control valve  170  is seated on the valve seat  166  and a contacting portion  172  thereof is away from a valve seat  163 , the fuel space  190  is communicated via a communicating passage  191  to the first control chamber  60  and also to the second control chamber  65 . A fuel space  192  around a rod  187  is communicated with a low pressure fuel passage  193 . 
     Next, an operation of the injector  7  is described. 
     (1) In a state that the voltage is not applied to the piezo element  180 , the hydraulic pistons  183  and  186  are positioned as shown in FIG.  23 . The control valve  170  is seated on the valve seat  166  of the valve seat element  165  by a biasing force of the spring  173 . As the communication between the fuel space  190  and the low pressure fuel space  192  is interrupted, the fuel space  190  is under high pressure due to high pressure fuel supplied from the fuel passage  51 . The first and second control chambers  60  and  65 , which are communicated with the fuel space  190 , are under high pressure. As an area of the control piston  27  receiving fuel pressure from the second control chamber  65  is larger than that receiving fuel pressure from the first control chamber  60 , the control piston  27  is urged downwardly in FIG.  23  and in contact with a shoulder portion  161  of the valve holder  160 . The control piston  24  and the needle  21  receive fuel pressure from the first control chamber  60  and are seated on the valve seat of the valve body  12  to close the injection hole. 
     (2) When the voltage is applied to the piezo element  180  and the piezo element  180  is expanded, the hydraulic piston  183  is moved downward in FIG.  23 . Presuming that the expanded amount of the piezo element  180 , that is, the moved amount of the hydraulic piston  183 , is L, a cross sectional area of the hydraulic piston  183  is Ahl and a cross sectional area of the hydraulic piston  186  is Ahs, the hydraulic piston  186  is driven by the piezo element  180  to move downward by (L×Ahl/Ahs) in FIG.  23 . As the rod  187  of the hydraulic piston  187  is in contact with the control valve  170 , the L downward expansion of the piezo element  180  causes the control valve  170  to move downwardly by (L×Ahl/Ahs) in FIG.  23 . 
     {circle around (1)} When the contacting portion  171  of the control valve  170  leaves the valve seat  166  and the contacting portion  172  comes in contact with the valve seat  163  of the valve holder  162  due to the expansion of the energized piezo element  180 , the first control chamber  60  is communicated with the low pressure fuel passage  93  via the communicating passage  191 , fuel space  190 , a opening portion between the contacting portion  171  and the valve seat  166 , and the fuel space  192 . As an area of the opening portion between the contacting portion  171  and the valve seat  166  is larger than a passage area of the throttle  195  through which high pressure fuel is supplied to the fuel space  190 , pressure of the first control chamber  60  is reduced. The fuel pressure reduction in the first control chamber  60  causes the control piston  24  and the needle  21  to lift so that fuel is injected. 
     As the contacting portion  172  is seated on the valve seat  163  and the second control chamber  65  is closed, fuel pressure in the second control chamber is maintained. Therefore, when the control piston  24  lifts by h 1  and runs into the control piston  27 , the control piston  24  is retained to the control piston  27  due to the fuel pressure of the second control chamber  65  (refer to FIG. 25 (A)). 
     {circle around (2)} When a smaller current voltage than that {circle around (1)} mentioned above is applied to the piezo element  180  and the movement amount of the control valve  170  becomes smaller than (L×Ahl/Ahs), the control valve  170  is kept at a position where the control valve  170  leaves not only the valve seat  163  but also the valve seat  166 . Then, the first and second control chambers  60  and  65  are communicated via the fuel space  170 , the opening portion between the contacting portion  171  and the valve seat  166 , and the fuel space  192  to the low pressure fuel passage  193  so that fuel pressure in the first and second control chambers  60  and  65  may be reduced. When the control piston  24  lifts and runs into the control piston  27  according to the fuel pressure reduction of the second control chamber  65 , the needle  21  together with the control pistons  24  and  27  lifts by (h 1 +h 2 ) until the control piston  27  is stopped by an end surface of the valve holder  162  on a side of the needle  21  as shown in FIG.  25 (B), as the fuel pressure of the second control chamber  65  is reduced, too. {circle around (3)} When the piezo element  180  is deenergized after a lapse of a given time, the piezo element  180  contracts to a position shown in FIG.  23 . Then, the hydraulic piston  186  is moved upward in FIG. 23 by a biasing force of the spring  188  and the control valve  170  is seated on the valve seat  166  due to a biasing force of the spring  173 . The communication of the first and second control chambers  60  and  65  with the low pressure fuel passage is interrupted so that fuel pressure of the both control chambers may increase. Accordingly, the control piston  24  and the needle  21  are urged in a direction of closing the injection hole by the fuel pressure of the first control chamber  60  so that fuel injection may be stopped. 
     According to the twelfth embodiment, as the control valve  170  is driven by the expansion and contraction of the piezo element  180 , an opening and closing response of the injector  7  may be improved, compared to a case that the control valve is driven by a magnetic attracting force of energized coils. 
     (Thirteenth Embodiment) 
     A thirteenth embodiment of the present invention is described with reference to FIG.  26 . With respect to components and construction substantially same to those of the eleventh embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. 
     Provided is a bypass passage  200 , which communicates a fuel passage  202  connecting the second control chamber  65  and the electromagnetic valve  30  to the fuel in-flow passage  50  for introducing high pressure fuel of the common rail. The bypass passage is provided with a throttle  201 , whose passage area is smaller than that of the outlet throttle  67 . A fuel passage  205  connects the first control chamber  60  and the electromagnetic valve  30 . 
     When the valve portion  30   c  of the electromagnetic valve  30  is selected, the control valve  27  lifts so that the control piston  24  and the needle may lift by (h 1 +h 2 ). Then, when the valve portion  30   a  of the electromagnetic valve  30  is selected by deenergizing the coil  35  of the electromagnetic valve  30 , high pressure fuel is supplied from the common rail via the throttle  201  in addition to the inlet throttle  66  to the second control chamber  65 . An increasing rate of the fuel pressure in the second control chamber  65  is higher than that according to the eleventh embodiment. As a valve closing speed of the needle, which moves from the lifting amount (h 1 +h 2 ) to the lifting amount h 1  as shown in FIG. 28A, becomes higher, fuel to be injected from the injection hole may be rapidly interrupted, resulting in decreasing unburned emissions. The valve closing speed of the needle may be controlled by adjusting the passage area of the throttle  201 . 
     (Modification) 
     Instead of the bypass passage  200  connecting the fuel in-flow passage  50  and fuel passage  202 , a bypass passage  206  with a throttle  207  is provided as shown in FIG.  27 . The bypass passage  206  communicates the fuel passage  51  for introducing high pressure fuel of the common rail to the first control chamber  60  with a fuel passage  205 . A passage area of the throttle  207  is smaller than that of the outlet throttle  62 . 
     For example, in a state that the control piston  24  and the needle lift by h 1 , the valve portion  30   a  of the electromagnetic valve  30  is selected by deenergizing the coil  35  of the electromagnetic valve  30 , high pressure fuel is supplied from the common rail via the throttle  207  in addition to the inlet throttle  61  to the first control chamber  60 . An increasing rate of the fuel pressure in the first control chamber  60  is higher than that according to the eleventh embodiment. As a valve closing speed of the needle, which moves from the lifting amount h 1  till the injection hole is closed as shown in FIG. 28A, becomes higher, fuel to be injected from the injection hole may be rapidly interrupted, resulting in decreasing unburned emissions. 
     The valve closing speed of the needle may be controlled by adjusting the passage area of the throttle  207 . Further, both of the bypass passages  200  and  206 , which have the throttles  201  and  207 , respectively, may be provided. In this case, the valve closing speed from the lifting amount (h 1 +h 2 ) to the injection hole closing may be totally increased. 
     According to the eleventh to thirteenth embodiments, the first control chamber  60  is formed between the control pistons  24  and  27  and the control pistons  24  and  27  do not come in contact with each other in a lifting amount range from 0 to h 1 . The injection hole may be opened and closed by controlling fuel pressure of the first control chamber  60  and a lifting amount of the needle  21  may be stepwise changed by controlling fuel pressure of the second control chamber  65 . 
     Further, though the two stages lifting is described according to the embodiments mentioned above, three or more than three stages lifting is available, for example, in such a way that three or more than three springs are provided for biasing the valve body element in a direction of closing the injection hole and three or more than three control chambers are provided for applying fuel pressure to the valve body element in a direction of closing the injection hole. 
     (Fourteenth Embodiment) 
     A construction of a fuel injector according to a fourteenth embodiment is described with references to FIGS. 29A,  29 B,  30  and  31 . FIGS. 29A and 29B are cross sectional views of the fuel injector. FIG. 30 is a partial cross sectional view showing a second lifting state of a valve element of the fuel injector shown in FIGS. 29A and 29B. FIG. 31 is a partial cross sectional view showing a first lifting state of a valve element of the fuel injector shown in FIGS. 29A and 29B. 
     According to the fuel injector  301  basically shown in FIGS. 29A and 29B, a first control piston  321  and a second control piston  322  on an upper side of the first control piston  321  are disposed in a housing  310 . A first control chamber  350  is formed between the first and second control pistons  321  and  322  and a second control chamber  351  is formed on an upper end surface of the second control piston  322 . Fuel pressure of the first and second control chambers  350  and  351  are controlled by an electromagnetic valve  330  provided above the second control chamber  351  so that a lifting amount of a needle  323 , which is provided below the first control chamber  350  for opening and closing an injection hole  311 , may be changed to secure an adequate shape of the injection rate. 
     A valve body  313  is fastened via a tip packing  314  to the housing  310  by a retaining nut  312 . A control device  320  is composed of the first control piston  321 , the first control chamber  350 , the second control piston  322  and the second control chamber  351 . The needle  323  and a rod  324 , which work with the control device  320 , are arranged on a side of the injection hole relative to the control device  320 . The needle  323  is held slidably and reciprocatingly in the valve body  313 . A first needle spring  315  is provided for urging the needle  323  via the rod  324  toward the injection hole  311 . 
     The housing  310  is provided with a high pressure passage  360  communicated with a common rail (not shown). The high pressure passage  360  is communicated via the housing  310 , the tip packing  314  and the valve body  313  to a fuel accumulating space  316  formed in the valve body  313 . Further, the high pressure passage  360  is communicated via a communicating passage  368  to the second control chamber  351 . Accordingly, high pressure fuel supplied from the common rail is supplied via the high pressure passage  360  to the second control chamber  351  and the fuel accumulating space  316 . Further, the fuel is supplied, as shown in FIG. 30, via a communicating passage  361  opened to the second control chamber  351  and a valve chamber  362  described later, from the second control chamber  351  to the first control chamber  350 . 
     A control valve  330  housed in a valve cover  338 (electromagnetic valve) is fastened by screw between an upper part of the housing  310  and the valve cover  338 . The control valve  330  is composed of a body  331 , an armature  332 , a stopper  333 , a first spring  334 , an electromagnetic coil  335 , a second spring  336 , a valve element  337 , a plate  339  and a valve chamber  362 . 
     The valve chamber  362  is formed in the body  331  and the valve element  337  connected to the armature  332  is housed in the valve chamber  362 . A second opening  365  to be communicated with the communicating passage  361  is opened on an upper end surface of the valve chamber  362  at a portion where the armature  332  and the valve element are connected to each other. A first opening  366  to be communicated with the communicating passage  364  is opened near on a central side surface of the valve chamber  362 . A low pressure opening  367  is opened on a lower end surface of the valve chamber  362  through the plate  339 . 
     The low pressure opening  367  is communicated with a low pressure passage  363 , which is formed in the housing  310  and is communicated with a fuel tank (not shown) for releasing fuel in the valve chamber to the fuel tank. 
     The valve element  337  may be seated on the low pressure opening  367  by a biasing force of the first spring  334  through the armature  332 . The valve element  337  may also be seated on the second opening  365  by moving upward with the armature  332  due to an attracting force of the electromagnetic coil  335 . 
     FIGS. 29A and 29B show a state, when the electromagnetic coil  335  is not energized, that the valve element  337  is seated on the low pressure opening  367  and the needle  323  is seated on a valve seat  313 A by the biasing force of the first spring  315  and fuel pressure of the first and second control chambers  350  and  351 . In FIGS. 29A and 29B, a reference number  323   a  show a shoulder portion of the needle  323  and a reference number  311   a  shows a lower end surface of the housing  311 . 
     As shown in FIG. 31, the armature  332  positioned above the valve element  337  is moved upwardly against the biasing force of the first spring  334  by an electromagnetic attracting force exerted by energizing the coil  335  so that the valve element  337  may lift by a first lifting amount until the valve element  337  comes in contact with a lower end of a stopper  333 . 
     The valve element  337  stops after moving a lift distance L 1 , as shown in FIG. 29A, since the valve element  337  receives a biasing force of a second spring  336  at this position so that the attracting force exerted by the coil  335  is balanced with a sum of the biasing forces of the first and second springs  334  and  336 . 
     When higher current is supplied to the electromagnetic coil  335  and the attracting force to the valve element  337  becomes higher, the valve element  337  further lifts against the sum of the biasing forces of the first and second springs  334  and  336 . Then, as shown in FIG. 30, the valve element  337  lifts by a second lifting amount until the valve element  337  comes in contact with the second opening  365  provided in the valve chamber  362  so that the valve element  337  may close the second opening and stop at this position. As shown in FIG. 29A, a lifting amount of the valve element  337  from a position where the valve element  337  is seated on the low pressure opening  367  to a position where the valve element  337  is in contact with the second opening  365  is L 2 . Therefore, a moving amount of the valve element  337  from the first lifting amount to the second lifting amount is (L 2 −L 1 ). 
     Next, an operation of the fuel injection valve  301  is described with reference to FIGS. 29A,  29 B,  30 ,  31  and  32 . 
     Current for driving the electromagnetic coil  335 , a value of which is controlled by an engine control apparatus (ECU) according to engine operations, is supplied to the coil  335 . The electromagnetic attracting force of the coil  335  exerted by the current supply attracts the armature  332  for lifting the valve element  337 . 
     When the valve element  337  shows the lifting amount L 2  (refer to FIG. 30 and a timing (A) of FIG.  32 ), the passage between the second control chamber  351  and valve chamber  362  is closed as the opening  365  is closed, while the communication between the valve chamber  362  and the low pressure passage  363  is kept. That is, the second control chamber  351 , to which high pressure fuel is supplied from the common rail (not shown), in interrupted to communicate with the low pressure passage  363 . On the other hand, the first control chamber  350  is communicated via the first opening  366  of the valve chamber  362  to the low pressure passage  363  so that fuel pressure (PC 1 ) of the first control chamber  350  may be reduced. Accordingly, as a sum of a pre-load biasing force of a first needle spring  315  and a force of receiving fuel pressure in the first control chamber  350 , both of which act in a direction of closing the injection hole, becomes smaller than a force of moving upward the needle  323  due to fuel pressure of the fuel accumulating space  316  so that the needle  323  may start lifting. According to the fuel pressure decrease of the first control chamber  350 , the needle  323  continues to lift and, after the needle  323  moves by a L 1  lift, the first piston  321  comes in contact with an end surface of the second piston  322 . At this time, as the fuel pressure (PC 2 ) of the second control chamber  351  is kept high, the force acting in a direction of closing the injection hole due to the fuel pressure of the second control chamber  351  is larger than the force of moving upward the needle  323  so that a lifting amount of the needle  323  may not exceed the L 1  lift. 
     When the valve element  337  shows the lifting amount L 1  (refer to FIG. 30 and a timing (B) of FIG.  32 ), the first and second control chambers  350  and  351  are communicated to the low pressure passage  363  as all of the first, second and low pressure openings  366 ,  365  and  367  are opened. As a result, fuel pressure of the first and second control chambers  350  and  351  are reduced. Therefore, the force acting in a direction of closing the injection hole becomes smaller than a force of moving upward the needle  323  so that the needle may move by a L 2  lift so as to exceed the L 1  lift. At this time, the shoulder portion  323   a  of the needle  323  is retained by the lower end surface  311   a  of the housing  311  to stop a further movement of the needle  323 . 
     As shown in a timing (C) of FIG. 32, it is possible to move stepwise from the L 1  lift to the L 2  lift by changing the lifting amount of the valve element  337  from L 2  to L 1  during a fuel injection period. 
     Then, after a lapse of a predetermined time and when the current for driving the electromagnetic coil  335  is cut off and the valve element  337  closes the low pressure opening  367 , fuel pressure of the first and second control chambers  350  and  351  increase, since the communication between the low pressure passage  363  and the valve chamber  362  is interrupted, so that the first and second pistons  321  and  322  may move in order for the needle  323  to close the injection hole. 
     When the valve element  37  shows the second lift L 2  and only the first piston  321  lifts, that is, when the needle  323  moves by the L 1  lift, high pressure fuel of the high pressure passage  360  never releases to the low pressure passage according to the fourteenth embodiment. Therefore, ineffective works of the fuel pump for delivering high pressure fuel to the injector may be limited so that fuel consumption of the engine may improve. 
     (Modification) 
     According to a modification of the fourteenth embodiment, in addition to the first needle spring  315  for urging the needle  323  in a direction of closing the injection hole  311 , a second needle spring  317  is provided in the second control chamber  351 . 
     The second needle spring  317  is operative to urge the second piston  322  in a direction of closing the injection valve in addition to fuel pressure of the second control chamber  351  when the first piston  321  lifts and comes in contact with the second piston  322  according to fuel pressure decrease of the first control chamber  350  so that the second piston  322  may not be moved upward by an inertia force due to the lift of the first piston  321 . As mentioned above, the second needle spring  317  serves to make the needle  323  lift accurately by the L 1  lift so that the fuel injection valve may inject a stable injection amount. 
     (Fifteenth Embodiment) 
     A fifteenth embodiment of the present invention is described with reference to FIG.  34 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the fourteenth embodiment is that the electromagnetic coil  335  is disposed at a lower part of the armature  332 . According to the fifteenth embodiment, the attracting force on energizing the coil  335  acts to move downward the armature  332  so that the valve element  337  may lift downwardly. The low pressure opening  367  is positioned on an upper side of the valve chamber  362  and, when current for driving the coil  335  is not supplied, the low pressure opening  367  is closed so that fuel pressure of the first and second control chambers  350  and  351  may increase and the needle  323  may close the injection hole. As the low pressure passage  363  is connected on the upper side of the valve chamber  362 , fuel leakage from a clearance  331   a  between the valve element  337  and a body  331  may be reduced. 
     (Sixteenth Embodiment) 
     A sixteenth embodiment of the present invention is described with reference to FIG.  35 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the fourteenth embodiment is that, instead of the electromagnetic coil  335  for diving the valve element  337 , a piezo element  401  is used. The piezo element  401  is contained in the housing  311  and, when current voltage is applied to the piezo element  401  according to a demand of a control computer (not shown), is expanded in an axial direction of the needle  323 . 
     As an upper end of the piezo element  401  is retained by the housing  311 , the expansion of the piezo element  401  urges a hydraulic piston  402 , which is biased upwardly by a spring  404  and whose movement is followed to the movement of the piezo element  401 . A movement of the first hydraulic piston  402  is transferred via a hydraulic chamber  403  to a second hydraulic piston  405  so that a lift amount of the second hydraulic piston corresponds to an expanded amount of the piezo element  401  multiplied by a ratio of a cross sectional area AH 1  of the hydraulic piston  402  to a cross sectional area AH 2  of the second hydraulic piston  405 . 
     The hydraulic chamber  403  is formed by the housing  311  and the hydraulic pistons  402  and  405 . An upward movement of the second hydraulic piston  405  is restricted by a stopper  408  and a spring  406  urges the second piston  405  upwardly. The spring  406  is positioned in an inner space of the housing  311  and the inner space  407  is communicated via the low pressure passage  363  to the fuel tank (not shown). 
     There is a small gap between a small diameter portion  409  of the second hydraulic piston  405  and the valve element  337  urged to the low pressure opening  367  in the valve chamber  362  by a spring (not shown) and, when the second hydraulic piston  405  moves downward, the small diameter portion  409  moves to come in contact with the valve element  337  and, then, to make the valve element  337  move downward so that the low pressure opening  367  may be opened. The valve chamber  362  is communicated via the passage  364  to the first control chamber  350  and via the passage  361  to the second control chamber  351 . The second pressure chamber  351  is connected to the high pressure passage  360  communicated to the common rail (not shown). 
     The injection valve according to the sixteenth embodiment, in which a lift amount of the valve element  337  is controlled by changing current to be applied to the piezo element  401 , has a same operation as disclosed in the fourteenth embodiment. 
     When the piezo element  401  is driven to move the valve element  337  with a high lifting amount so that the needle  323  may lift by the L 1  lift, the first hydraulic piston  402  is driven against the biasing force of the spring  404  according to the expansion of the piezo element  401  so that pressure in the hydraulic chamber may increase. The increased hydraulic pressure in the hydraulic chamber  403  causes to drive the second hydraulic piston  405  against the biasing force of the spring  406 . The small diameter portion  409  comes in contact with the valve element  337  and drives to move downwardly the valve element  337  so that the valve element  337  may come in contact with the plate  339  to interrupt the communication between the inner space  407  and the passage  361 . As the valve element  337  moves downwardly, the first control chamber  350  is communicated via the passage  364  and the inner space  407  to the low pressure passage  363  so that pressure of the first control chamber is reduced. Accordingly, the needle  323  opens the injection hole since the force acting in a direction closing the injection hole becomes weaker. The first piston  321  comes in contact with the second piston  322  according to the upward movement of the needle  323  and a further lift movement of the first piston  321  stops at that place since pressure of the second chamber  351  is high. 
     When the piezo element  401  is driven to move the valve element  337  with a low lifting amount, the small diameter portion  409  of the second hydraulic piston  405  comes in contact with the valve element  337  and drives to move downwardly the valve element  337  to an extent that the valve element  337  does not come in contact with the plate  339 . The first and second control chambers  350  and  351  are communicated via the passages  364  and  362  and the inner space  407  to the low pressure passage  363  so that pressure of the first and second control chambers are reduced. Therefore, even after the first piston  321  comes in contact with the second piston  322 , the needle  323  continues to lift by the L 2  lift until the needle  323  comes in contact with the tip packing  314  since the force acting in a direction closing the injection hole becomes lower than that of moving upwardly the needle  323 . 
     Further, the injection rate in a boot shape may be secured by changing the expansion length of the piezo element  401  during the injection period. As the control valve of the piezo element  401  mentioned above may rapidly response to current supply for the expansion, the fuel injection valve having a better lifting response of the needle  323  may be realized. 
     (Seventeenth Embodiment) 
     An seventeenth embodiment of the present invention is described with reference to FIG.  36 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the fourteenth embodiment is that the high pressure conduit is directly communicated to the first control chamber and the lifting amount (the L 1  lift) of the needle  323  is restricted by a movement of the second piston  322 . 
     An operation of the injection valve according to the seventeenth embodiment is described hereinafter. 
     When the valve element  337  shows the lifting amount L 2 , the communication between the first control chamber  350  and the low pressure passage  363  is interrupted since the valve element  337  closes the second opening  365 . The first control chamber  350  keeps a high fuel pressure state as the high pressure is introduced via the high pressure passage and a communicating passage  402  to the first control chamber  350 . on the other hand, fuel pressure of the second control chamber  351  is reduced since the second control chamber  351  is communicated via the communicating passage  261 , the first opening  366  and the low pressure opening  367  to the low pressure passage  363 . Accordingly, the force of urging the second piston  322  in a direction of closing the injection hole becomes low and the second piston  322  moves upwardly (by the L 1  lift) until the second piston  322  comes in contact with and be stopped by a stopper  401  provided at an upper portion of the second control chamber  351 . 
     The area of the first control chamber  350  is changed in a direction of reducing fuel pressure in the control chamber  350  according to the upward movement of the second piston  322 . However, as high pressure fuel amount supplied to the first control chamber  350  from the communication passage  402  is controlled by a throttle  403  so that the first control chamber  350  may keep the high pressure, the first piston may maintains a clearance  12 . 
     When the valve element  337  shows the lifting amount L 1 , pressure of the first and second control chambers  350  and  351  are both reduced and the needle  323  further lift and moves by the L 2  lift. With the construction mentioned above, the adjustment of the L 1  lift may become simpler. 
     (Eighteenth Embodiment) 
     An eighteenth embodiment of the present invention is described with reference to FIG.  37 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. A difference from the fourteenth embodiment is a point that high pressure fuel is introduced to the second control chamber  351  from the high pressure passage  360  through a passage different from the passage of the fourteenth embodiment. 
     According to the fourteenth to sixteenth embodiments, the passage through which high pressure fuel is introduced to the second control chamber  351  from the high pressure passage  360  is the communicating passage  368 . According to the eighteenth embodiment, instead of the communicating passage  368 , a communicating passage  668  is provided so as to connect the high pressure passage  360  and the passage  361  which communicates the valve chamber  362  and the second control chamber  351 . The communicating passage  668  is connected to the passage  361  on a side of the valve chamber  362  with respect to a throttle  601  disposed in the passage  361 . 
     With the construction mentioned above, one of the throttles disposed in the communicating passages from the high pressure passage  360  to the first control chamber  350  may be eliminated as a number from the throttles described according to the fourteenth to sixteenth embodiments. 
     When the valve element  337  closes the low pressure opening  367  (when the lifting amount of the valve element  337  is zero), fuel supply to the first control chamber  350  becomes smoother due to the one elimination of the throttles so that pressure increase in the first control chamber  350  may become faster. As a result, force acting in a direction of closing the injection hole may be rapidly increased so that the downward speed of the needle  323  becomes faster so as to improve the valve opening response characteristic of the needle  323 . 
     (Nineteenth Embodiment) 
     A nineteenth embodiment of the present invention is described with reference to FIG.  38 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. According to the nineteenth embodiment, a downward speed of the needle  323  is improved by a method different from that described in the eighteenth embodiment. 
     A difference from the fourteenth embodiment is that a communicating passage  701 , through which high pressure fuel is introduced from the high pressure passage  360  to the second control chamber  351 , is added. 
     As shown in FIG. 38, the high pressure passage  360  is communicated via a throttle  702  through the communicating passage  701  to the first control chamber  350 . High pressure fuel from the high pressure passage  360  can be introduced to the first control chamber  350  not only through the passage  364  via the valve chamber  362  but also through the passage  701 . 
     Therefore, when the needle  323  closes the injection hole, fuel flow amount to the first control chamber  350  may increase so that pressure increase in the first chamber becomes faster. It is necessary to decide a flow area of the throttle  702  between the high pressure passage  360  and the first control chamber  350  to an extent that fuel leak amount from the high pressure passage  360  to the first control chamber  350  does not increase when the needle  323  closes the injection hole. 
     (Modification) 
     According to a modification of the nineteenth embodiment, as shown in FIG. 39, instead of the throttle  601  provided in the passage  361  communicating the valve chamber  362  and the second control chamber  351 , a throttle  703  is provided in the low pressure passage  363 . 
     When the valve element  337  lift downward in FIG. 39, high pressure fuel of the second control chamber  351  is released via the passage  361 , the valve chamber  362  and the low pressure passage  363 . The throttle  703 , which is provided on a way of pressure releasing passages, serves to adjust a pressure reducing speed from high pressure to low pressure in the second control chamber  351 . 
     According to the present embodiment, as the throttle  701  is not provided in the passage  361  connecting the high pressure passage  360  to the first control chamber  350 , fuel flow amount to the first control chamber  350  may increase, when the needle  323  closes the injection hole, so that pressure increase in the first chamber becomes faster and, thus, the downward speed of the needle  323  may improve. 
     (Twentieth Embodiment) 
     A twentieth embodiment of the present invention is described with reference to FIG.  40 . With respect to components and construction substantially same to those of the fourteenth embodiment, to which the same reference numbers are affixed, the explanation thereof is omitted. According to the twentieth embodiment, a downward speed of the needle  323  is improved by a method different from that described in the eighteenth or nineteenth embodiment. 
     A difference from the fourteenth embodiment is that a communicating passage  801 , through which high pressure fuel is introduced from the high pressure passage  360  to the second control chamber  351 , is added. 
     As shown in FIG. 40, the first control chamber  350  is communicated via a throttle  802  through a communicating passage  801  provided in the second piston  322  to the second control chamber  351 . High pressure fuel from the high pressure passage  360  can be introduced to the first control chamber  350  not only through the passage  364  via the valve chamber  362  but also through the passage  801  via the passage  368  and the second control chamber  351 . 
     Therefore, when the needle  323  closes the injection hole, fuel flow amount to the first control chamber  350  may increase so that pressure increase in the first chamber becomes faster. It is necessary to decide a flow area of the throttle  802  between the high pressure passage  360  and the first control chamber  350  to an extent that fuel leak amount from the second control chamber  351  to the first control chamber  350  does not increase when the needle  323  closes the injection hole. 
     Further, if the construction according to the twentieth embodiments is combined with those according to the eighteenth and nineteenth embodiments, a downward lifting speed of the needle  323  becomes further faster so that a sharp cut characteristic of the injection rate may much more improve. 
     According to the twentieth embodiment, a throttle  803  is disposed in the passage  364  provided in the plate  339 . The throttle  803  may be provided by forming a long narrow hole in the plate  339  whose diameter is decided to adjust fuel flow amount. 
     (Modification) 
     FIG. 41 shows a modification of the twentieth embodiment. The communicating passage  364  constituted by the long narrow hole in the plate  339  is provided with a tapered opening  364   a  enlarged without being contracted toward the valve chamber  362 . The tapered opening  364   a  on a side of an enlarged portion thereof is opened to the valve chamber  362 . 
     As high pressure fuel from the high pressure passage  360  is introduced to the first control chamber  350  via the second control chamber  351  and the valve chamber  362 , the communicating passage for introducing high pressure to the first control chamber  350  becomes relatively long. Accordingly, it takes a longer time before the chamber  350  is highly pressurized. According to the present embodiment, as the tapered opening  364   a  on a side of introducing high pressure fuel is wider, high pressure maybe easily and rapidly introduced to the first control chamber  350 .